Method for producing a paper-plastic container and paper-plastic container

Abstract

The application provides a paper-plastic container production method and a paper-plastic container. The paper-plastic container production method comprises the following steps: a wet blank forming treatment to obtain a paper-plastic wet blank; a wet blank processing treatment to make a barrier material adhere to the paper-plastic wet blank through a suction slurry process to obtain a barrier wet blank; and a paper-plastic forming treatment to make the barrier wet blank into a paper-plastic container. The paper-plastic container production method provided by the application makes the barrier material adhere through the suction slurry process in the paper-plastic wet blank state, which can make the barrier material more uniformly distributed and reduce the amount of the barrier material, so that the paper-plastic container with the barrier material layer has improved barrier performance, does not need a plastic inner container, and has improved environmental protection. In addition, only one heat drying treatment is needed in the whole production process, the energy consumption is low, the whole process is simple, no additional spraying, film coating or injection molding equipment is needed, the production efficiency is high, the production cost is reduced, and the environmental protection is improved.

Description

Technical Field

[0001] This application relates to the field of pulp molding technology, and in particular to a method for producing a paper-plastic container and the paper-plastic container itself. Background Technology

[0002] Since industrialization, plastic products have been widely used in daily life and production. However, plastic products are difficult to degrade, which puts a burden on the environment. With the introduction of the concept of environmental friendliness, the paper-plastic industry, which is made from biodegradable plant fibers, is booming.

[0003] To achieve the purpose of storing liquid, most existing paper-plastic products involve internal spraying, internal film coating, or internal injection molding of thermoformed pulp molded containers. This process is complex, has high production costs, and is still not environmentally friendly. Summary of the Invention

[0004] To address the aforementioned technical problems, this application provides a method for producing paper-plastic containers and a paper-plastic container. The process is simple and can improve environmental friendliness. Furthermore, the resulting paper-plastic container has uniform barrier properties.

[0005] In a first aspect, embodiments of this application provide a method for producing a paper-plastic container, comprising: wet blank forming process to obtain a paper-plastic wet blank; wet blank processing process to allow a barrier material to adhere to the paper-plastic wet blank through a slurry suction process to obtain a barrier wet blank; and paper-plastic forming process to form the barrier wet blank into a paper-plastic container.

[0006] According to an embodiment of the first aspect of this application, the wet blank processing steps include at least one slurry suction process to form at least one barrier material layer.

[0007] According to the first aspect of this application, the wet blank processing step includes two or more suction processes to form two or more barrier material layers, wherein at least two barrier material layers are made of different materials.

[0008] According to an embodiment of the first aspect of this application, in the step of processing the wet blank, a barrier material is attached to the inner wall and / or outer wall of the wet blank.

[0009] According to an embodiment of the first aspect of this application, the wet blank processing includes: providing a wet blank processing mold and a vacuum filtration device; fixing the wet blank in the wet blank processing mold and immersing it in a barrier material, and then using the vacuum filtration device to perform vacuum treatment on the wet blank processing mold to obtain a barrier wet blank, wherein the vacuum value of the vacuum treatment is -0.08 to -0.1 MPa.

[0010] According to the first aspect of this application, in the wet preform forming process, the moisture content of the paper-plastic wet preform is 60%-80%.

[0011] According to the embodiments of the first aspect of this application, the barrier material includes one or more of polyolefins and their derivatives, polyurethanes and their derivatives, polylactic acid and its derivatives, polyhydroxyalkanoates and their derivatives, acrylates and their derivatives, and cellulose esters and their derivatives.

[0012] According to the embodiment of the first aspect of this application, the processing time of the suction process is 5s to 30s.

[0013] According to the first aspect of this application, in the paper-plastic molding process, the barrier wet blank is dried at 115°C to 125°C for 2-5 minutes.

[0014] Secondly, this application provides a paper-plastic container produced by the above-described production method.

[0015] The paper-plastic container production method provided in this application attaches barrier material through a suction process while the paper-plastic preform is in a wet state. This allows for more uniform distribution of the barrier material and reduces the amount of barrier material used. The resulting paper-plastic container with a barrier material layer has improved barrier performance and eliminates the need for a plastic inner liner, thus improving environmental friendliness. Furthermore, the entire production process requires only one heat drying treatment, resulting in lower energy consumption. The process is simple, requiring no additional spraying, coating, or injection molding equipment, leading to high production efficiency, reduced production costs, and improved environmental friendliness. Attached Figure Description

[0016] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0017] Figure 1 This is a schematic diagram of a wet blank processing method provided in an embodiment of this application;

[0018] Figure 2 This is a schematic diagram of a wet preform forming process provided in an embodiment of this application;

[0019] Figure 3 This is a schematic diagram of a paper-plastic molding process provided in an embodiment of this application;

[0020] Figure 4 This is a schematic diagram of a paper-plastic container provided in an embodiment of this application.

[0021] The attached figures are labeled as follows:

[0022] 10. Wet preform forming mold; 11. Barrier material tank; 14. Pulp tank; 15. Thermoforming mold; 16. Bottle neck shaping component;

[0023] 20. Paper-plastic wet preform; 21. Barrier wet preform; 22. Paper-plastic container; A. Direction of vacuum airflow.

[0024] The realization of the objectives, functional features, and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. The accompanying drawings have illustrated specific embodiments of this application, which will be described in more detail below. These drawings and textual descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concepts of this application to those skilled in the art through reference to specific embodiments. Detailed Implementation

[0025] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0026] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element. Furthermore, components, features, and elements with the same names in different embodiments of this application may have the same meaning or different meanings, the specific meaning of which must be determined by its interpretation in that specific embodiment or further in conjunction with the context of that specific embodiment.

[0027] It should be understood that although the terms first, second, third, etc., may be used in this document to describe various types of information, this information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, without departing from the scope of this document, first information may also be referred to as second information, and similarly, second information may also be referred to as first information.

[0028] It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of this application.

[0029] Since industrialization, plastic products have been widely used in daily life and production. However, plastic products are difficult to degrade, which puts a burden on the environment. With the introduction of the concept of environmental friendliness, the paper-plastic industry formed by biodegradable paper is booming.

[0030] Paper-plastic containers are generally paper products made from plant fibers and molded into a certain shape. The inventors of this application have noted that, in order to store liquids, most existing paper-plastic containers undergo internal spraying, internal lamination, and internal injection molding after thermoforming. This process is complex, has high production costs, and is still not environmentally friendly.

[0031] In view of this, in a first aspect, this application provides a method for producing a paper-plastic container, comprising:

[0032] The process involves wet preform forming to obtain a paper-plastic wet preform; wet preform processing to attach barrier material to the paper-plastic wet preform through a slurry suction process to obtain a barrier wet preform; and paper-plastic forming to manufacture a paper-plastic container from the barrier wet preform.

[0033] In the embodiments of this application, paper-plastic containers include, but are not limited to, paper bottles, paper cups, lunch boxes, trays, egg cartons, egg trays, fruit trays, flower pots, disposable medical bedpans, etc.

[0034] In some embodiments, the wet preform forming process may include a pulping step. As an example, the pulping step includes crushing and loosening the pulp raw material to obtain a homogeneous pulp. The pulp raw material includes at least one of waste paper and virgin plant fibers. Virgin plant fiber raw materials include coniferous wood, broadleaf wood, reeds, bamboo, crop straw, bagasse, etc. For example, the pulp raw material may be waste paper, or a mixture of waste paper and bagasse; this application does not specifically limit this. It is understood that the pulping step may include impurity removal and soaking of the pulp raw material before crushing and loosening, in order to quickly obtain a pure, homogeneous pulp while reducing wear and tear on the crushing machine. The pulping step may also include disinfecting the pulp raw material or homogeneous pulp to ensure that the final paper-plastic container meets hygiene standards.

[0035] In some embodiments, during the wet preform forming process, a paper-plastic wet preform can be obtained by injecting pulp into a wet preform forming mold. It is understood that different paper-plastic containers correspond to different wet preform forming molds. The shape of the inner wall of the wet preform forming mold matches the shape of the outer wall of the paper-plastic container to be prepared, or the shape of the outer wall of the wet preform forming mold matches the inner wall of the paper-plastic container to be prepared, thus forming the desired paper-plastic container. The inner or outer wall contour of the paper-plastic container can be of various shapes, such as cubic, cylindrical, or other regular or irregular shapes. This application does not specifically limit this. For example, the wet preform forming mold for producing the paper-plastic container has a first inner wall, and the inner cavity formed by the first inner wall is cylindrical. Pulp can adhere to the first inner wall to form a paper-plastic wet preform with a cylindrical shape. Alternatively, the wet preform forming mold for producing the paper-plastic container has a first outer wall, and the shape of the first outer wall is cubic. Pulp can adhere to the first outer wall to form a paper-plastic wet preform with a cubic shape.

[0036] The pulp can be formed in the paper-plastic molding die using one or both of the following methods: suction molding or pouring molding. Suction molding utilizes a vacuum filtration device, connecting the paper-plastic molding die to the device and applying vacuum to adhere the pulp to the die. Pulp pouring involves filling the paper-plastic molding die with pulp, holding it for a period of time, and then pouring out the remaining pulp. For a preferred example, please refer to [reference needed]. Figure 2 The paper-plastic wet blank 20 can be prepared by a suction process, which includes immersing the wet blank forming mold 10 into the pulp tank 14 containing pulp, connecting a vacuum filtration device (not shown) to the wet blank forming mold 10, turning on the vacuum filtration device, so that the pulp is adsorbed onto the wet blank forming mold 10, and obtaining a pre-formed paper-plastic wet blank. After dehydration, the pre-formed paper-plastic wet blank 20 is obtained.

[0037] The vacuum filtration device can be a vacuum pump; for example, please refer to [link to relevant documentation]. Figure 2 The direction A of the vacuum airflow in the wet preform forming mold is away from the liquid surface of the pulp, so that the pulp can be drawn into the wet preform forming mold.

[0038] Preferably, the paper-plastic molding mold 10 is immersed vertically into the pulp tank 14 so that the extension direction of the inner cavity of the formed paper-plastic wet blank 20 is perpendicular to the liquid surface of the pulp in the pulp tank 14, which helps to achieve a consistent wall thickness in all parts of the paper-plastic wet blank 20.

[0039] Optionally, in the step of obtaining the preformed paper-plastic wet preform, the vacuum value of the vacuum filtration device is -0.04 MPa to -0.08 MPa. For example, the vacuum values ​​of the vacuum filtration device are -0.08 MPa, -0.07 MPa, -0.06 MPa, -0.05 MPa, and -0.04 MPa. Having the vacuum value of the vacuum filtration device within the above range allows the pulp to adhere more uniformly to the wet preform forming mold and also prevents the pulp from being sucked out of the wet preform forming mold.

[0040] The preformed paper-plastic wet blank has a high moisture content and is difficult to shape. In this case, the paper bottle forming mold can be removed from the pulp tank, and the preformed paper-plastic wet blank can be dehydrated to remove some moisture, thus obtaining the paper-plastic wet blank. The dehydration process can be vacuuming, heating, or other commonly used dehydration methods. Preferably, vacuuming is used for dehydration. Please continue reading. Figure 2 During vacuuming, the paper-plastic molding mold 10 can be inverted to prevent the pre-formed paper-plastic wet blank from falling off. Optionally, in the dehydration step of the pre-formed paper-plastic wet blank, the vacuum value of the vacuum filtration device is -0.04 MPa to -0.08 MPa. For example, the vacuum value of the vacuum filtration device is -0.04 MPa, -0.05 MPa, -0.06 MPa, -0.07 MPa, or -0.08 MPa. The dehydration time is 10 min to 15 min; for example, the dehydration time is 10 min, 11 min, 12 min, 13 min, 14 min, or 15 min. Dehydration of the pre-formed paper-plastic wet blank makes it easier to form and also facilitates uniform adsorption during the subsequent slurry suction process. In this application, the thickness of the paper-plastic wet blank can be controlled according to the required thickness of the paper-plastic container, and the thickness of the paper-plastic wet blank can be adjusted by the duration of the slurry suction process. Optionally, in the step of forming the paper-plastic wet preform, the suction process takes 5 to 20 seconds. For example, the suction process time can be 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 seconds. By keeping the suction process time within the above range, the thickness of the paper-plastic container can be between 0.5 mm and 0.8 mm, achieving good strength while saving on raw materials and time costs.

[0041] In the wet preform forming process, the adhesion of barrier material to the wet preform via a suction process can include: immersing the paper-plastic wet preform, fixed to a wet preform processing mold, together with the mold, into a barrier material tank containing the barrier material; connecting a vacuum filtration device to the wet preform processing mold; activating the vacuum filtration device; and allowing the barrier material to adhere to the paper-plastic wet preform, thus obtaining a barrier wet preform. For an example, please refer to [link to example]. Figure 1The paper-plastic wet blank can remain in its original position in the wet blank forming mold 10. At this time, the wet blank forming mold 10 continues to be used as a wet blank processing mold. The paper-plastic wet blank and the wet blank forming mold 10 are immersed together in the barrier material pool 11 containing barrier material. The vacuum filtration device is connected to the wet blank forming mold 10, and the vacuum filtration device (not shown in the figure) is turned on, so that the barrier material is adsorbed onto the paper-plastic wet blank, and the barrier wet blank is obtained.

[0042] Using a suction process to attach barrier material to the wet paper-plastic preform requires immersing the preform in a barrier material tank. This ensures full contact between the preform and the barrier material, improving the uniformity of the barrier material's adhesion. Furthermore, this suction process allows the same mold to be used for both the preform and the molding process, keeping the preform and mold stationary. This ensures a smooth workflow, high production efficiency, and prevents deformation of the preform during processing, thus increasing the yield of the finished product.

[0043] Paper-plastic wet blanks are coated with barrier materials to form barrier wet blanks. After molding, these barrier wet blanks have a barrier function and can be used to hold items, which can be gases, liquids, or solids.

[0044] The inventors of this application have noticed that, due to the excellent water absorption of dry bare paper-plastic containers, contact between the dry bare paper-plastic container and the barrier material results in rapid absorption of the barrier material, making it impossible to control the uniformity of absorption. Therefore, compared to coating the barrier material onto the dry bare paper-plastic container, the embodiments of this application perform the slurry absorption process in the wet state to allow the barrier material to adhere to the wet paper-plastic blank, thus avoiding uneven coating of the barrier material caused by the excellent water absorption of the dry paper bottle. Furthermore, coating the barrier material in the wet state also avoids the increase in the amount of barrier material required due to the excellent water absorption of the dry paper-plastic container.

[0045] In the paper-plastic molding process, a paper-plastic container can be obtained by molding a wet blank. For example, the molding process can be a heat-pressurization process.

[0046] In summary, the paper-plastic container production method provided in this application attaches barrier material through a suction process while the paper-plastic preform is in a wet state. This allows for more uniform distribution of the barrier material and reduces the amount of barrier material used. The resulting paper-plastic container with a barrier material layer improves barrier performance, eliminates the need for a plastic inner liner, and enhances environmental friendliness. Furthermore, the entire production process requires only one heat drying treatment, consumes less energy, is simple in process, has high production efficiency, reduces production costs, and improves environmental friendliness.

[0047] In some embodiments, the wet blank processing steps include at least one slurry suction process to form at least one barrier material layer.

[0048] According to the embodiments of this application, the suction process can be performed once, twice, three times, or more. Two or more suction processes can attach two or more layers of barrier material to the wet paper-plastic preform. The barrier material layers are multi-layered, which can improve the barrier effect. As an example, after performing one suction process to form a barrier material layer, the paper can be left to stand for a period of time or have some moisture removed before performing a second suction process. When performing multiple suction processes, the above process can be repeated.

[0049] When the barrier material layer consists of two or more layers, the barrier material layers are stacked. The materials of the two or more barrier material layers can be the same or different. When the barrier material layers are of the same material, they can be processed in a barrier material pool of the same material, which can save operating space.

[0050] In some embodiments, the wet blank processing step includes two or more suction processes to form two or more barrier material layers, wherein at least two barrier material layers are made of different materials.

[0051] At least two layers of barrier material can be made of different materials, and different types of barrier materials can be used in combination. Two or more layers can be used, including two, three, four, or more layers. When there are more than two layers, at least two layers can be made of different materials; for example, multiple layers of barrier material can be made of different materials, or only two layers can be different. The combination of barrier materials can be considered based on usage needs, price, or other factors. As an example, when storing food, plant-based barrier materials can be used on the side that comes into contact with the food to improve safety, while more economical barrier materials can be chosen for the layers that do not directly contact the food.

[0052] In some embodiments, during the wet blank processing steps, a barrier material is adhered to the inner and / or outer walls of the wet blank.

[0053] Barrier materials can be attached only to the inner wall of the wet paper-plastic preform, or only to the outer wall, or both the inner and outer walls can be attached simultaneously.

[0054] When barrier material is attached only to the inner wall or only to the outer wall of the wet paper-plastic preform, the wet preform forming mold can also serve as the wet preform processing mold. That is, after the wet paper-plastic preform is formed in the wet preform forming mold, it can remain stationary in the mold. The mold is then immersed in a barrier material pool, bringing the wet paper-plastic preform into contact with the barrier material. A vacuum filtration device is then connected to the wet preform forming mold, and the vacuum filtration device is activated, allowing the barrier material to adhere to the wet paper-plastic preform, resulting in a barrier-free wet preform. This simplifies the production process of paper-plastic containers.

[0055] For example, when only the barrier material is attached to the inner wall of the paper-plastic wet blank, in the wet blank forming process, the wet blank forming mold has a first inner wall. The pulp is attached to the first inner wall by the pulp suction process to form the paper-plastic wet blank. In the wet blank processing process, the wet blank forming mold can also be used as the wet blank processing mold. The paper-plastic wet blank is kept in place in the wet blank forming mold. The wet blank forming mold is immersed in the barrier material pool containing the barrier material. At this time, the inner wall of the paper-plastic wet blank is in contact with the barrier material. The vacuum filtration device is connected to the wet blank forming mold, and the vacuum filtration device is turned on so that the barrier material is adsorbed onto the paper-plastic wet blank, resulting in a barrier wet blank with the barrier coating attached to the inner wall.

[0056] For example, when only the barrier material is attached to the outer wall of the paper-plastic wet blank, in the wet blank forming process, the wet blank forming mold has a first outer wall. The pulp is attached to the first outer wall by the pulp suction process to form the paper-plastic wet blank. In the wet blank processing process, the wet blank forming mold can also be used as a wet blank processing mold. That is, after the paper-plastic wet blank is formed by the wet blank forming mold, the paper-plastic wet blank can be kept stationary on the wet blank forming mold. The wet blank forming mold is then immersed in a barrier material pool containing the barrier material. At this time, the outer wall of the paper-plastic wet blank is in contact with the barrier material. The vacuum filtration device is connected to the wet blank forming mold, and the vacuum filtration device is turned on to allow the barrier material to be adsorbed onto the paper-plastic wet blank, resulting in a barrier wet blank with a barrier coating attached to the outer wall.

[0057] When barrier material is attached to both the inner and outer walls of a wet paper-plastic preform, a matching wet preform forming mold and a wet preform processing mold can be used. These molds can be nested so that one of the inner and outer walls of the wet paper-plastic preform is in contact with the forming mold, and the other with the processing mold. When the forming and processing molds are immersed in the barrier material bath at different stages, the inner and outer walls of the wet paper-plastic preform come into contact with the barrier material respectively, thus allowing the barrier material to adhere to both walls through a suction process. Attaching barrier material to both the inner and outer walls of the paper-plastic container expands its application environment, allowing it to be used in humid environments. For example, after a paper-plastic wet blank is formed on the first outer wall of the wet blank forming mold, the inner wall of the paper-plastic wet blank is attached to the first outer wall of the wet blank forming mold, keeping the paper-plastic wet blank in place on the wet blank forming mold. The wet blank forming mold is then immersed in a barrier material pool containing barrier material. At this time, the outer wall of the paper-plastic wet blank is in contact with the barrier material, and the barrier material is attached to the outer wall of the paper-plastic container. Then, the wet blank processing mold is placed on the outer wall of the paper-plastic wet blank, so that the outer wall of the paper-plastic wet blank is attached to the inner wall of the wet blank processing mold. At this time, the wet blank forming mold is removed, and the exchange of the paper-plastic wet blank between the wet blank forming mold and the wet blank processing mold is completed. The wet blank processing mold is then immersed in a barrier material pool containing barrier material. At this time, the inner wall of the paper-plastic wet blank is in contact with the barrier material, and the barrier material is attached to the inner wall of the paper-plastic container.

[0058] In some embodiments, the wet blank processing includes: providing a wet blank processing mold and a vacuum filtration device; fixing the paper-plastic wet blank in the wet blank processing mold and immersing it in a barrier material, and then using the vacuum filtration device to vacuum the wet blank processing mold to obtain a barrier wet blank, wherein the vacuum value of the vacuum filtration process is -0.08 to -0.1 MPa.

[0059] The vacuum filtration device can be a vacuum pump with a vacuum value in the range of -0.08 to -0.1 MPa, which can have a good adsorption effect while avoiding damage to the wet paper-plastic preform. Optionally, the vacuum value for vacuuming is -0.08 MPa, -0.09 MPa, -0.1 MPa, etc.

[0060] In some embodiments, the moisture content of the paper-plastic wet preform is 60%-80% during the wet preform forming process.

[0061] According to the embodiments of this application, a moisture content within the above-mentioned range can, on the one hand, maintain the shape of the wet paper-plastic preform and prevent deformation, and on the other hand, give the wet paper-plastic preform suitable absorbency to facilitate the uniform coating of barrier materials. Optionally, the moisture content of the wet paper-plastic preform is 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, or 80%, etc.

[0062] In some embodiments, the barrier material includes one or more of polyolefins and their derivatives, polyurethanes and their derivatives, polylactic acid and its derivatives, polyhydroxyalkanoates and their derivatives, acrylates and their derivatives, and cellulose esters and their derivatives.

[0063] In some embodiments, the barrier material includes at least one of one or more of polyolefins, polyolefin derivatives, polyurethanes, polyurethane derivatives, polylactic acid, polylactic acid derivatives, polyhydroxyalkanoates, polyhydroxyalkanoate derivatives, acrylates, acrylate derivatives, cellulose esters, and cellulose ester derivatives.

[0064] The embodiments of this application impart barrier properties to paper-plastic containers by attaching a barrier material to a wet paper-plastic preform to form a barrier material layer. The barrier material can consist of a single component or a mixture of multiple components. Exemplarily, the barrier material can be polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), ethylene vinyl alcohol (EVOH), or ethylene vinyl acetate (EVA), or a mixture of polypropylene (PP) and polyethylene terephthalate (PET), or a mixture of cellulose esters and cellulose ester derivatives. This application uses plant-based barrier materials, which can improve environmental friendliness and safety. As an example, the mass percentage of the barrier material in the barrier tank is 35% to 65%. Optionally, the mass percentage of the barrier material in the barrier tank is 40%, 42%, 45%, 48%, 50%, 52%, 55%, 58%, or 60%. A mass percentage of the barrier material in the barrier tank within the above range can save time in the paper-plastic molding process and simultaneously help improve the uniformity of slurry absorption.

[0065] It is understandable that barrier materials may also include acid / alkalinity modifiers, oxidants, and surfactants. For example, the acid / alkalinity modifier may be sodium bicarbonate, the oxidant may be ammonium persulfate, and the surfactant may be sodium dodecyl sulfate, all of which are used to improve the stability of the barrier material in solution.

[0066] In this application, the thickness of the barrier material layer can be controlled according to the barrier requirements of the paper-plastic container application. The thickness of the barrier material layer can be adjusted by the processing time of the slurry suction process. In some embodiments, the processing time of the slurry suction process is 5s to 30s. For example, the processing time of the slurry suction process is 5s, 6s, 7s, 8s, 9s, 10s, 11s, 12s, 13s, 14s, 15s, 16s, 17s, 18s, 19s, 20s, 25s, or 30s. By keeping the processing time of the slurry suction process within the above range, the thickness of the barrier material layer can be made between 10μm and 50μm, which can achieve a good barrier effect while saving raw material and time costs.

[0067] In some embodiments, during the paper-plastic molding process, the barrier wet preform is dried at a temperature of 115°C to 125°C for 2 to 5 minutes. Drying the barrier wet preform under these conditions can increase the dehydration rate while preventing excessive dehydration of the paper-plastic container, making it easier to control the shape of the container. For example, the processing temperature of the barrier wet preform is 115°C, 116°C, 117°C, 118°C, 119°C, 120°C, 121°C, 122°C, 123°C, 124°C, or 125°C, and the processing time at these temperatures is 2 minutes, 3 minutes, 4 minutes, or 5 minutes.

[0068] As an example, please refer to Figure 3 The paper-plastic forming process includes transferring the barrier wet blank 21 from the wet blank processing mold (here the wet blank forming mold 10 is used as the wet blank processing mold) to the thermoforming mold 15. The transfer method can be clamping with a clamp, or placing an elastomer bag into the inner cavity of the barrier wet blank, so that the elastomer bag expands and fits against the inner wall of the barrier wet blank, and the barrier wet blank 21 is transferred from the wet blank processing mold to the thermoforming mold 15 by moving the elastomer bag.

[0069] During the wet preform shaping stage, the elastomer bag is expanded to maintain a first preset pressure value and adheres to the inner wall of the barrier wet preform. The thermoforming mold 15 is then engaged, maintaining a second preset pressure value. The elastomer bag and thermoforming mold 15 apply pressure to the inner and outer walls of the barrier wet preform 21, respectively, which allows the barrier wet preform 21 to maintain its shape during dehydration. This application does not specifically limit the first and second preset pressure values, as long as they can fix the barrier wet preform 21 during dehydration. Optionally, the first preset pressure value is 0.4 MPa to 0.6 MPa, and the second preset pressure value is 13.5 MPa to 14.5 MPa. A second preset pressure value greater than the first preset pressure value allows for a denser pulp distribution during the formation of the paper-plastic container 22, improving the quality of the paper-plastic container 22. For example, the first preset pressure value is 0.4 MPa, 0.5 MPa or 0.6 MPa, and the second preset pressure value is 13.5 MPa, 14 MPa or 14.5 MPa.

[0070] Please continue reading. Figure 3 and Figure 4 For example, when the paper-plastic container 22 is a paper bottle, when the thermoforming mold 15 is fastened, a bottle mouth shaping component 16 can be added at the port position of the thermoforming mold 15. The bottle mouth shaping component 16 can be used to shape the bottle mouth that blocks the wet blank 21 so that the paper bottle has the required shape. The bottle mouth shaping component 16 can be flat, threaded, or other required shapes.

[0071] Alternatively, the elastomeric bag can be inflated by filling it with gas or liquid.

[0072] Secondly, this application provides a paper-plastic container produced by the above-described production method.

[0073] The paper-plastic container provided in this application uses a suction process to attach a barrier material layer to the wet paper-plastic blank, which can obtain a uniform barrier material layer. The paper-plastic container with the barrier material layer has improved barrier performance, does not require a plastic liner, and improves environmental protection. The paper bottle provided in this application embodiment is integrally molded, the production process is simple, and it is suitable for large-scale production.

[0074] Example 1:

[0075] A paper-plastic container includes a container wall and a barrier material layer attached to the inner wall of the container. The container wall has a thickness of 0.6 mm, and the barrier material layer has a thickness of 20 μm. The preparation method includes:

[0076] Wet preform forming process: Place the paper-plastic molding die into the pulp tank with the pulp inlet facing downwards. Turn on the vacuum filtration device to perform a pulp suction process, allowing the pulp to adhere to the inner wall of the molding die. The vacuum value is -0.05 MPa, and the suction time is 10 seconds, resulting in a preformed paper-plastic wet preform with a moisture content of 70%-80%. Remove the molding die from the pulp tank and invert it (i.e., pulp inlet facing upwards). Continue vacuuming with a vacuum value of -0.05 MPa and a dewatering time of 15 minutes. After dewatering, a paper-plastic wet preform with a moisture content of 60%-65% is obtained.

[0077] Wet Preform Processing: The paper-plastic wet preform and the paper-plastic molding die are kept relatively fixed. The paper-plastic molding die is placed in a barrier material tank with the slurry inlet facing downwards. A vacuum filtration device is used for slurry suction processing, allowing the barrier material to be adsorbed onto the inner wall of the paper-plastic wet preform. The solute in the barrier material tank is a mixture of component a: 10.0wt% ammonium persulfate aqueous solution containing 3.5% wt% sodium bicarbonate, component b: 10.0wt% sodium dodecyl sulfate aqueous solution, and component c: a 90:10 mixture of vinyl acetate / acrylic acid. The content of component a is 11.65 wt%, component b is 27.72 wt%, and component c is 60.63 wt%. The vacuum value is -0.08 MPa, and the suction time is 15 seconds. After adsorption is complete, the paper-plastic molding die is removed from the barrier material tank and left to stand for 5 minutes to allow the barrier material to be fully absorbed by the paper-plastic wet preform, resulting in a barrier wet preform.

[0078] Wet Preform Forming Process: Open the paper-plastic molding die and transfer the wet preform using an elastomer bag to the thermoforming die. The elastomer bag expands by inflation. After closing the thermoforming die, the elastomer bag expands by high-temperature inflation (120℃) for 3 minutes. The inflation pressure of the elastomer bag is 0.6 MPa, and the thermoforming die's pressure is 14 MPa. After forming, close the air valve to release the gas inside the elastomer bag, remove the elastomer, open the thermoforming die, and remove the finished paper-plastic container.

[0079] Example 2

[0080] A paper-plastic container includes a container wall and a barrier material layer attached to the inner wall of the container. The container wall has a thickness of 0.8 mm, and the barrier material layer has a thickness of 30 μm. The preparation method includes:

[0081] Wet blank forming process: Similar to Example 1, except that the slurry absorption time is 15s.

[0082] Wet blank processing: Similar to Example 1, except that the slurry absorption time is 20 seconds. Wet blank forming processing: Similar to Example 1, except that the thermoforming temperature is 125°C and the drying time is 2 minutes.

[0083] Example 3

[0084] A paper-plastic container includes a container wall and barrier material layers attached to the inner and outer walls of the container. The container wall has a thickness of 0.6 mm, the barrier material layer on the inner wall has a thickness of 20 μm, and the barrier material layer on the outer wall has a thickness of 35 μm. The preparation method includes:

[0085] Wet preform forming process: The paper-plastic molding mold is placed in a pulp tank with the same composition as in Example 1. A vacuum filtration device is activated to perform a pulp suction process, allowing the pulp to adhere to the outer wall of the mold. The vacuum value is -0.05 MPa, and the suction time is 12 seconds, resulting in a preformed paper-plastic wet preform with a moisture content of 70%-80%. The paper-plastic molding mold is removed from the pulp tank, inverted, and vacuum is continued from -0.04 MPa to -0.05 MPa. The dewatering time is 15 minutes, resulting in a paper-plastic wet preform with a moisture content of 65%-70%.

[0086] Wet blank processing: The paper-plastic wet blank and the paper-plastic molding die are kept relatively fixed. The paper-plastic molding die is placed in a barrier material tank. The composition of the barrier material tank is the same as that in the barrier material tank in Example 1. A vacuum filtration device is used to perform a suction process, so that the barrier material is adsorbed onto the inner wall of the paper-plastic wet blank. The vacuum value is -0.08 MPa, and the suction time is 15 seconds. After the adsorption is completed, the paper-plastic molding die is removed from the barrier material tank and left to stand for 5 minutes to allow the barrier material to be fully absorbed by the paper-plastic wet blank, resulting in a barrier wet blank with barrier material adhering to the outer wall.

[0087] A barrier wet preform with barrier material adhering to its outer wall is fixed to a wet preform processing mold. The wet preform forming mold is removed, and the wet preform processing mold is placed in a barrier material tank with the slurry inlet facing downwards. A vacuum filtration device is used to perform a slurry suction process, allowing the barrier material (polyacrylate) to be adsorbed onto the inner wall of the barrier wet preform. The vacuum value is -0.08 MPa, and the suction time is 20 seconds. After adsorption is complete, the paper-plastic forming mold is removed from the barrier material tank and left to stand for 5 minutes to allow the barrier material to be fully absorbed by the paper-plastic wet preform, resulting in a barrier wet preform with barrier material adhering to both its inner and outer walls.

[0088] Wet preform forming process: The wet preform is transferred to a thermoforming mold using a transfer device. After the thermoforming mold is closed, an elastomer bag is placed inside the cavity of the wet preform. The elastomer bag is inflated by high-temperature inflation. The thermoforming temperature is 120℃, and the drying time is 3 minutes. The inflation pressure of the elastomer bag is 0.6MPa, and the thermoforming mold's hot-pressing pressure is 14MPa. After forming, the gas valve is closed to release the gas inside the elastomer bag, the elastomer is removed, the thermoforming mold is opened, and the finished product, the paper-plastic container, is taken out.

[0089] Comparative Example 1

[0090] A paper-plastic container includes a container wall and a barrier material layer attached to the inner wall of the container. The container wall has a thickness of 0.6 mm, and the barrier material layer has a thickness of 20 μm. The preparation method includes:

[0091] Wet blank forming process: Same as in Example 1.

[0092] Wet blank processing: Keep the paper-plastic wet blank and the paper-plastic molding die relatively fixed. Insert the spraying device into the paper-plastic wet blank through the opening, turn on the spraying device, and spray the barrier material from the spray nozzle onto the inner wall of the paper-plastic wet blank. The barrier material has the same composition as the barrier material tank in Example 1. The spraying time is 20 seconds. After spraying, let it stand for 5 minutes to allow the barrier material to be absorbed.

[0093] Wet Preform Forming Process: The paper-plastic wet preform with barrier material attached is transferred to a thermoforming mold using a transfer device. After the thermoforming mold is closed, an elastomer bag is placed inside the cavity of the paper-plastic wet preform with barrier material attached. The elastomer bag is inflated by high-temperature inflation. The thermoforming temperature is 120℃, and the drying time is 3 minutes. The inflation pressure of the elastomer bag is 0.6MPa, and the thermoforming mold's hot pressing pressure is 14MPa. After forming, the gas valve is closed to release the gas inside the elastomer bag, the elastomer is removed, the thermoforming mold is opened, and the finished product, the paper-plastic container, is taken out.

[0094] Performance testing of paper-plastic containers

[0095] The water vapor transmission rate was tested according to the method specified in GB / T 1037-2021, weight reduction method, condition A. The experimental results are shown in Table 1.

[0096] Table 1. Experimental results of water vapor transmission rate in Examples 1-3 and Comparative Example 1.

[0097] Example 1 Example 2 Example 3 Comparative Example 1 Water vapor transmission rate <![CDATA[22g / cm 2 ·day]]> <![CDATA[20g / cm 2 ·day]]> <![CDATA[15g / cm 2 ·day]]> <![CDATA[232g / cm 2 ·day]]>

[0098] As can be seen from Table 1, the water vapor transmission rate of the paper-plastic containers in Examples 1-3 is much lower than that in Comparative Example 1, which shows that the paper-plastic containers prepared by the production method of the paper-plastic containers provided in this application can achieve good barrier function.

[0099] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A method for producing a paper-plastic container, characterized in that, include: The paper-plastic wet preform is formed by adsorbing pulp onto a wet preform forming mold to obtain a preformed paper-plastic wet preform. The preformed paper-plastic wet preform is then dehydrated to obtain a paper-plastic wet preform with a moisture content of 60%-80%. The wet blank processing involves adhering a barrier material to the paper-plastic wet blank through a suction process to obtain a barrier wet blank. The wet blank processing includes keeping the paper-plastic wet blank in its original position in a wet blank forming mold, which continues to be used as a wet blank processing mold. The paper-plastic wet blank and the wet blank forming mold are immersed together in the barrier material, and a vacuum filtration device is used to vacuum the wet blank processing mold to obtain the barrier wet blank. The vacuum value of the vacuum filtration process is -0.08 to -0.1 MPa, and the suction process time is 5 to 30 seconds. Paper-plastic molding process to form the barrier wet blank into a paper-plastic container.

2. The method for producing paper-plastic containers according to claim 1, characterized in that, The wet blank processing steps include at least one slurry suction process to form at least one barrier material layer.

3. The method for producing paper-plastic containers according to claim 2, characterized in that, The wet blank processing steps include two or more suction processes to form two or more barrier material layers, wherein at least two of the barrier material layers are made of different materials.

4. The method for producing a paper-plastic container according to any one of claims 1-3, characterized in that, In the wet blank processing step, the barrier material is attached to the inner wall and / or outer wall of the paper-plastic wet blank.

5. The method for producing paper-plastic containers according to claim 1, characterized in that, Barrier materials include one or more of the following: polyolefins and their derivatives, polyurethanes and their derivatives, polylactic acid and its derivatives, polyhydroxyalkanoates and their derivatives, acrylates and their derivatives, and cellulose esters and their derivatives.

6. The method for producing a paper-plastic container according to claim 5, characterized in that, In the paper-plastic molding process, the barrier wet blank is dried at 115℃~125℃ for 2 min-5 min.

7. A paper-plastic container, characterized in that, It is produced by the production method described in any one of claims 1-6.

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