S-shaped jute fiber three-dimensional structure and preparation method thereof

Abstract

The invention relates to the technical field of jute layered product preparation, in particular to an S-shaped jute fiber three-dimensional structure and a preparation method thereof.The method comprises the steps that a jute fiber felt layer and a hot melting polyester fiber felt layer are obtained based on a jute fiber raw material bag and a hot melting polyester fiber raw material bag of a finished product; the jute fiber felt layers and the hot melting polyester fiber felt layers are sequentially stacked in a crossed mode, and jute layered product fiber stacks are obtained and marked as fiber stacks; placing the fiber stack in a mold for hot press molding; collecting the pressure of each preset position of the bottom of the fiber stack at each moment; collecting a visual image of the fiber stack at each moment; determining the hot-pressing inclination deviation of the fiber stack at each moment; obtaining the connection compactness of the fiber stack at each moment; the step length of pressure adjustment in the pressurization stage is corrected, and the pressure value of the pressurization stage at the next moment of the current moment is determined; demolding after hot press molding is finished, and naturally cooling to room temperature to obtain a jute layered product. Therefore, the mechanical property of the jute layered product is improved.

Description

Technical Field

[0001] This application relates to the technical field of the preparation of jute laminated products, and specifically relates to an S-shaped jute fiber three-dimensional structure and a preparation method thereof. Background Art

[0002] Jute belongs to the genus Corchorus of the family Tiliaceae and is an annual herbaceous plant. The S-shaped jute fiber made from jute has wide applications in the fields of building decoration materials, industrial products, home textile products, clothing products, etc. due to its advantages such as natural fiber, degradability, high physical strength, heat preservation and heat insulation.

[0003] The jute laminated product is a base material finished product prepared by a processing technology of laying jute fiber layers layer by layer, and subsequent jute finished products such as jute mattresses, jute decorative boards, jute sound-absorbing boards, jute clothing, etc. can be further processed and prepared. To improve the thickness and flexibility of the jute laminated product, a connection layer needs to be added between the jute fiber layers, and finally the jute laminated product is formed through a hot pressing process.

[0004] However, in the traditional preparation process of jute laminated products, hot pressing and forming are carried out through a staged pressure boosting process, which easily leads to non-uniform internal stress, uneven density and the risk of delamination in the produced jute laminated products, affecting the performance of the jute laminated products. Summary of the Invention

[0005] In order to solve the above technical problems, the purpose of this application is to provide an S-shaped jute fiber three-dimensional structure and a preparation method thereof, and the specific technical solutions adopted are as follows: In the first aspect, an embodiment of this application provides a preparation method for an S-shaped jute fiber three-dimensional structure, and the method includes the following steps: Based on the finished jute fiber raw material package and the hot-melt polyester fiber raw material package, through unpacking, loosening, cotton feeding, carding, and web laying respectively, a jute fiber felt layer and a hot-melt polyester fiber felt layer are obtained; The jute fiber felt layer and the hot-melt polyester fiber felt layer are cross-stacked in sequence to obtain a jute laminated product fiber stack, denoted as the fiber stack; the fiber stack is placed in a mold for hot pressing and forming; during the pressurization stage of the hot pressing and forming, the pressures at each preset position at the bottom of the fiber stack at each moment are collected; and visual images of the fiber stack at each moment are collected at each preset azimuth angle; Analyze the dispersion degree and change rate of the pressures at all preset positions at each moment to determine the hot pressing inclination deviation of the fiber stack at each moment; determine the comprehensive deviation value at each preset azimuth angle and each moment of the fiber stack through the deviation degree of the connection boundary between adjacent jute fiber felt layers in the visual image compared with the horizontal line; Weighted fusion is performed on the comprehensive deviation values at all preset azimuth angles at each moment based on preset weights to obtain the connection density of the fiber stack at each moment; combining the hot pressing tilt deviation and the connection density, the step size of the pressure adjustment in the pressing stage is corrected to determine the pressure value in the next moment of the current moment in the pressing stage; After the hot pressing forming is completed, demolding is carried out, and natural cooling is performed to room temperature to obtain the jute laminated product.

[0006] In one embodiment, the hot-melt polyester fiber raw material package is 4080 hot-melt fiber with a melting point of 180~280°C.

[0007] In one embodiment, the first layer and the last layer of the fiber stack are both jute fiber felt layers; the areal density of the jute fiber felt layer is 50~250 g / m 2 , and the thickness is 1~3 mm; the areal density of the hot-melt polyester fiber felt layer is 100~600 g / m 2 , and the thickness is 0.2~0.5 mm.

[0008] In one embodiment, the hot pressing forming includes a preheating stage and a pressing and forming stage. The temperature in the preheating stage is 200°C~250°C, and the duration is 10~20 min; the duration of the pressing and forming stage is 20 min~40 min.

[0009] In one embodiment, the determination of the hot pressing tilt deviation includes: Calculate the sum value of the gradients of the pressures at all preset positions at each moment. The hot pressing tilt deviation is positively correlated with both the degree of dispersion and the modulus of the sum value.

[0010] In one embodiment, the determination of the comprehensive deviation value includes: Perform edge detection on the visual images at each moment and each preset azimuth angle, obtain the boundary line formed after the melting of the hot-melt polyester fiber felt layer between adjacent jute fiber felt layers in each visual image, and calculate the sum of the distances between all pixel points on the boundary line and the horizontal line; Based on the sum of the distances of all boundary lines in each visual image, determine the comprehensive deviation value.

[0011] In one embodiment, the comprehensive deviation value is the mean value of the sum of the distances of all boundary lines in each visual image.

[0012] In one embodiment, the determination of the connection density includes: The weight range of the azimuth angle closest to the direction of the sum value is [0.3, 0.5), the weights of the remaining azimuth angles are equal, and the sum of the weights of all azimuth angles is 1; The connection density is the reciprocal of the weighted sum of the comprehensive deviation values of all preset azimuth angles at each moment.

[0013] In one embodiment, determining the pressure value of the next moment of the current moment in the pressurization stage includes: For each moment, calculate the normalization result of the ratio of the connection density to the hot pressing tilt deviation, and calculate the ratio of the interval length of the preset pressure range in the pressure forming stage to the duration of the pressure forming stage, denoted as the first ratio; The pressure adjustment amount at the next moment of the current moment is the product of the normalization result and the first ratio, and the pressure value of the pressurization stage at the next moment of the current moment is the sum of the pressure value at the current moment and the product; The density of the jute laminated product obtained by natural cooling to room temperature is 80~150 kg / m 3 , and the thickness is 2~5 cm.

[0014] In a second aspect, an S-shaped jute fiber three-dimensional structure provided by an embodiment of the present application is prepared by using the steps of the preparation method of the S-shaped jute fiber three-dimensional structure described in any one of the above.

[0015] The present application has at least the following beneficial effects: This application is based on a finished jute fiber raw material package and a hot-melt polyester fiber raw material package. Through unpacking, loosening, cotton feeding, carding, and web laying respectively, a jute fiber felt layer and a hot-melt polyester fiber felt layer are obtained; the jute fiber felt layer and the hot-melt polyester fiber felt layer are cross-stacked in sequence to obtain a jute layered product fiber stack, denoted as the fiber stack; the fiber stack is placed in a mold for hot pressing and forming; during the pressurization stage of hot pressing and forming, the pressures at each preset position at the bottom of the fiber stack at each moment are collected; and visual images of the fiber stack at each moment are collected at each preset azimuth angle; through the dual-modal perception of pressure and vision, the real-time multi-dimensional monitoring and intelligent dynamic regulation are deeply integrated, improving the accuracy and reliability of subsequent fiber stack pressure regulation; the dispersion degree and change rate of the pressures at all preset positions at each moment are analyzed to determine the hot pressing tilt deviation of the fiber stack at each moment; through the deviation degree of the connection boundary between adjacent jute fiber felt layers in the visual image compared to the horizontal line, the comprehensive deviation value of each preset azimuth angle of the fiber stack at each moment is determined; through the calculation of the hot pressing tilt deviation and the comprehensive deviation value, the uniformity of the fiber stack being heated and compressed and the interfacial bonding state are dynamically analyzed, and then the pressure parameters are adaptively adjusted; based on the preset weights, the comprehensive deviation values at all preset azimuth angles at each moment are weighted and fused to obtain the connection density of the fiber stack at each moment; combining the hot pressing tilt deviation and the connection density, the step size of pressure adjustment in the pressurization stage is corrected to determine the pressure value at the next moment of the current moment in the pressurization stage; effectively ensuring the density and isotropy of the internal structure of the jute layered product, significantly improving the interfacial bonding strength and overall mechanical properties, while avoiding the local overpressure or underpressure defects caused by traditional fixed pressure, optimizing the fiber distribution uniformity, and reducing the risk of warping deformation caused by uneven thermal stress; after the hot pressing and forming is completed, demolding is carried out, and it is naturally cooled to room temperature to obtain the jute layered product, improving the mechanical properties of the jute layered product. Description of the Drawings

[0016] To more clearly illustrate the technical solutions and advantages in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required to be used in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0017] Figure 1 It is a step flow chart of a method for preparing an S-shaped jute fiber three-dimensional structure provided by an embodiment of the present application; Figure 2 It is a schematic diagram of a jute layered product fiber stack; Figure 3 It is a front view of a schematic diagram of the hole distribution of a jute layered product; Figure 4Side view of the schematic diagram of the pore distribution of the jute laminated product; Figure 5 Schematic diagram of the complementary embedding connection structure of the jute laminated product. Specific implementation manners

[0018] In order to further elaborate on the technical means and effects adopted by this application to achieve the intended invention purpose, the following will, in conjunction with the accompanying drawings and preferred embodiments, elaborate in detail on a three-dimensional S-shaped jute fiber structure and its preparation method proposed according to this application, its specific implementation manners, structures, features, and effects. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. In addition, the specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which this application belongs.

[0020] The following will specifically describe the specific solutions of a three-dimensional S-shaped jute fiber structure and its preparation method provided by this application with reference to the accompanying drawings.

[0021] Embodiment 1 Please refer to Figure 1 , which shows the flowchart of the steps of a method for preparing a three-dimensional S-shaped jute fiber structure provided by an embodiment of this application. The method includes the following steps: S1. Based on the finished jute fiber raw material package and the hot-melt polyester fiber raw material package, through unpacking, opening, cotton feeding, carding, and web laying respectively, a jute fiber felt layer and a hot-melt polyester fiber felt layer are obtained.

[0022] In this embodiment, the finished three-dimensional S-shaped jute fiber package is prepared into a jute fiber felt layer through a web-forming unit. Specifically: First, use an unpacking machine to open the jute fiber raw material package to loosen the jute fiber raw material compacted during transportation; then, use an opening machine to further disperse the jute fiber raw material to facilitate subsequent web laying operations. Then, through a cotton feeding machine, the processed jute fibers are evenly transported to the carding machine at a stable speed. In the carding machine, the jute fibers are carded by the equipment brush to make them in a single fiber state and arranged in an oriented manner to form a relatively thin jute fiber web; finally, use a web laying machine to lay multiple layers of the relatively thin jute fiber web to form a jute fiber felt layer with a certain thickness and uniformity.

[0023] It should be noted that the web-forming unit in this embodiment includes an unpacking machine, an opening machine, a cotton feeding machine, a carding machine, and a web laying machine, aiming to disperse and lay the finished jute fiber raw material package to form a jute fiber felt layer with uniform texture. The areal density of the jute fiber felt layer in this embodiment is 50 g / m 2 , and the thickness is 1 mm.

[0024] In this embodiment, the same treatment process as that of the jute fiber felt layer is adopted, and the jute fiber raw material package therein is replaced with a hot-melt polyester fiber raw material package to prepare a hot-melt polyester fiber felt layer. The purpose of the hot-melt polyester fiber felt layer is that during the subsequent high-temperature hot pressing and shaping process, it can melt at high temperature, enabling adjacent jute fiber felt layers to be tightly connected, replacing the glue in the traditional process and reducing the risk of formaldehyde emission. Among them, the surface density of the hot-melt polyester fiber layer is 100 g / m 2 , and the thickness is 0.2 mm.

[0025] In addition, the hot-melt polyester fiber selected in this embodiment is required to have a melting point in the range of 180 - 280 °C. In this embodiment, 4080 hot-melt fiber is selected to prepare the hot-melt polyester fiber felt layer. Implementers can choose other existing hot-melt polyester fibers by themselves, such as core-sheath type low-melting-point polyester fiber, ES fiber, core-sheath type polyester stretch yarn, etc.

[0026] S2, Stack the jute fiber felt layer and the hot-melt polyester fiber felt layer crosswise in sequence to obtain a jute layered product fiber stack, denoted as the fiber stack; put the fiber stack into a mold for hot pressing and forming; collect the pressures at each preset position at the bottom of the fiber stack at each moment during the pressurization stage of the hot pressing and forming; and collect the visual images of the fiber stack at each moment with each preset azimuth angle.

[0027] Convey the prepared jute fiber felt layer and hot-melt polyester fiber felt layer to a cross-lapper. In the cross-lapper, the fiber felt layers on the same conveying chain can be folded and lapped, so as to present a lapping method of jute fiber felt layer - hot-melt polyester fiber felt layer - jute fiber felt layer - hot-melt polyester fiber felt layer -... - jute fiber felt layer. Through repeated stacking to reach the preset number of layers or thickness, thus forming a jute layered product fiber stack, simply denoted as the fiber stack. The schematic diagram of the jute layered product fiber stack is as Figure 2 shown, Figure 2 where 1 is the jute fiber felt layer and 2 represents the hot-melt polyester fiber felt layer.

[0028] Based on the prepared fiber stack, put the fiber stack into a mold through a conveying net clamp, and perform hot pressing and forming through a hot pressing and forming unit. First, preheat the hot pressing and forming unit to 200 °C, and the preheating duration is 10 min. After the preheating is completed, perform pressure forming on the fiber stack. Set the pressure range to 3 MPa - 15 Mpa, and the hot pressing duration is 20 min. Among them, the pressure value at the initial moment of the pressure forming is set to 3 MPa.

[0029] In the traditional hot pressing process, through staged pressure boosting, although the pressure boosting process is simple, due to the discontinuous pressure boosting, it is easy to cause the jute fiber mat layer and the hot-melt polyester fiber mat layer to be not tightly connected, affecting the strength and stability of the jute laminated product. Therefore, it is necessary to adjust the pressure boosting process of the hot pressing.

[0030] To cope with the intelligent control of hot pressing, it is necessary to collect data information on the hot pressing of fiber stacks. In this embodiment, taking any fiber stack as an example, pressure sensors are deployed on the lower bottom plate of the hot pressing mold and evenly distributed on the lower bottom plate. It is required that the pressure sensors be on the same plane as the lower bottom plate, and the information of a single pressure sensor can reflect the pressure value received by a local area on the hot pressing mold. High-definition vision sensors are deployed around the hot pressing mold, that is, high-definition vision sensors are deployed at the four azimuth angles of the east, west, south, and north of the hot pressing mold to obtain visual images of each azimuth angle of the fiber stack.

[0031] It should be noted that the lower bottom plate in the hot pressing mold is the bottom of the fiber stack. In this embodiment, the pressure sensors are evenly distributed at equal intervals, and the number of pressure sensors is 25. At the same time, the pressure sensors and the high-definition vision sensors collect data synchronously, and the collection interval is 1 s. The implementer can set the number of pressure sensors and the collection interval according to the actual situation, and this embodiment does not limit it here.

[0032] S3. Analyze the dispersion degree and change rate of the pressures at all preset positions at each moment, and determine the hot pressing inclination deviation of the fiber stack at each moment; determine the comprehensive deviation value at each moment of each preset azimuth angle of the fiber stack through the deviation degree of the connection boundary between adjacent jute fiber mat layers in the visual image compared with the horizontal line.

[0033] Since the jute fiber mat layer and the hot-melt polyester fiber mat layer are stacked layer by layer to obtain a fiber stack, under normal circumstances, the density of each position of the fiber stack is uniform. However, due to the limitation of natural jute fibers, there may be slight differences in fiber filaments, resulting in certain density differences at different positions of the fiber stack. Therefore, in the traditional hot pressing process with staged pressure boosting, defects such as stress concentration and delamination are likely to occur. Therefore, this embodiment optimizes and adjusts the hot pressing process.

[0034] Ideally, the pressure data at all positions at each acquisition moment should be relatively consistent, and the fluctuation of the pressure data is small. In actual situations, if there is uneven density in the fiber stack, there will be a tendency deviation of pressure, resulting in large fluctuations in the pressure data at all positions.

[0035] According to the above analysis, for each moment, the gradient information of the pressure data at each position is calculated, and the gradients of the pressure data at all positions are added together, denoted as the aggregated gradient B, which can represent the overall inclination degree of the pressure at all positions. Thus, the hot pressing inclination deviation of the fiber stack at each moment is constructed, and the specific calculation method is as follows: , where A represents the hot pressing inclination deviation of the fiber stack at each moment, represents the degree of dispersion of the pressure data at all positions of the fiber stack at each moment, represents the modulus of the aggregated gradient at each moment, and B represents the aggregated gradient at each moment.

[0036] It should be noted that in this embodiment, the calculation method of the degree of dispersion is calculated using the standard deviation, and the implementer can choose other existing feasible calculation methods for the degree of dispersion by himself. For example, variance, coefficient of variation, etc.

[0037] When the fiber stack density is balanced, the fluctuations of the pressure data at all positions are small, the value of the degree of dispersion is small, and there may be small directional deviations in the pressure data at all positions, but the deviations of each pressure data are inconsistent, so the modulus length of the obtained aggregated gradient is small. When the fiber stack density is uneven, there is a pressure tendency in the mold during the hot pressing forming process, so that the pressure value is larger at the position where the fiber stack density is smaller. Therefore, the gradient tendency of the pressure data at all positions of the fiber stack is more consistent, and the modulus length value of the obtained aggregated gradient is larger.

[0038] At the same time, based on the high-definition vision sensor, visual images of the fiber stack at each azimuth angle in the mold are obtained. Since there are obvious color differences between the jute fiber felt layer and the hot-melt polyester fiber felt layer, based on the prior information of the mold boundary area, the image area of the fiber stack is obtained. At the same time, for the image area of the fiber stack at each azimuth angle at each moment, the Canny edge detection algorithm is used to obtain the boundary line formed after the melting of the hot-melt polyester fiber felt layer between adjacent jute fiber felt layers within the image area. Then, a horizontal line closest to the boundary line is obtained as the horizontal baseline, and the sum of the distances between all pixel points on the boundary line and the horizontal baseline is calculated as the deviation value of the corresponding boundary line.

[0039] For the image area of the fiber stack at each azimuth angle at each moment, the mean value of the deviation values of all the boundary lines therein is used as the comprehensive deviation value of the fiber stack at each azimuth angle at each moment. In this embodiment, the number of azimuth angles is 4.

[0040] It should be understood that if the overall pressure of the jute fiber felt layer in the fiber stack is relatively uniform and consistent, the obtained boundary line is closer to a horizontal straight line, and the comprehensive deviation value is smaller. If the overall pressure is inconsistent, the boundary line of the jute fiber felt layer obtained at this time is more likely to have a large horizontal deviation, and the comprehensive deviation value is larger.

[0041] S4. Based on the preset weights, perform weighted fusion on the comprehensive deviation values of all preset azimuth angles at each moment to obtain the connection compactness of the fiber stack at each moment; combine the hot pressing tilt deviation and the connection compactness to correct the step size of the pressure adjustment in the pressing stage, and determine the pressure value of the next moment in the pressing stage at the current moment.

[0042] Furthermore, in this embodiment, based on the comprehensive deviation values of all azimuth angles at each moment, calculate the connection compactness of the fiber stack at each moment. Specifically: First, obtain the azimuth angle closest to the direction of the aggregation gradient, denoted as the first azimuth angle, and set the weight of the first azimuth angle to be the largest. In this embodiment, the weight of the first azimuth angle is set to 0.4, and the weights of the remaining azimuth angles are equal and the sum of the weights of all azimuth angles is 1. Therefore, in this embodiment, the weights of the remaining azimuth angles are all 0.2.

[0043] For each moment, based on the weights of each azimuth angle, perform weighted summation on the comprehensive deviation values of each azimuth angle, and take the reciprocal of the weighted summation result as the connection compactness of the fiber stack at each moment.

[0044] It should be noted that the value range of the weight of the first azimuth angle is [0.3, 0.5). The implementer can set the weight of the first azimuth angle according to the actual situation, and this embodiment does not limit it here; when the direction of the aggregation gradient is between two azimuth angles, at this time, both azimuth angles corresponding to the aggregation gradient are denoted as the first azimuth angle, and the weights of the two first azimuth angles are equal, and the weights of the remaining two azimuth angles are equal.

[0045] It should be understood that the azimuth angle closest to the direction of the aggregation gradient is the azimuth with the worst hot pressing forming, and thus has the greatest impact on the connection compactness during the hot pressing of the fiber stack. Therefore, the set weight is the largest. If the center consistency of the jute fiber felt layer is relatively high at each azimuth angle as a whole, it indicates that the overall compaction situation is good, the obtained comprehensive deviation value is small, and the connection compactness of the fiber stack is large.

[0046] Combine the hot pressing tilt deviation and the connection compactness of the fiber stack at the current moment to dynamically adjust the pressing process during the hot pressing forming of the fiber stack, so as to improve the strength and toughness of the jute laminated product during the hot pressing process.

[0047] First, calculate the pressure adjustment amount of the next moment of the fiber stack at the current moment. The specific calculation method is as follows: , where represents the pressure adjustment amount at the next moment of the current moment of the fiber stack, represents the step value of the pressure adjustment of the fiber stack. In this embodiment, the step value is the ratio of the interval length of the pressure range to the hot pressing duration, denoted as the first ratio. That is, the pressure range is 3MPa to 15Mpa, and the hot pressing duration is 20min; norm() is a normalization function, D represents the connection compactness of the fiber stack at the current moment, and A1 represents the hot pressing inclination deviation of the fiber stack at the current moment.

[0048] The sum of the pressure value of the fiber stack at the current moment and the pressure adjustment amount at the next moment of the current moment is used as the pressure value at the next moment of the current moment of the fiber stack, completing the dynamic adjustment of the pressure during the hot pressing forming process of the fiber stack.

[0049] It should be understood that during the hot pressing forming process, the pressure value increases steadily. Only when the overall hot pressing condition of the fiber stack is good, that is, the greater the connection compactness of the fiber stack and the smaller the hot pressing inclination deviation, can the pressure value be increased to the maximum extent at this time to improve production efficiency. When the density of the fiber stack is uneven, the pressure value needs to be increased slowly to improve the connection effect of the hot-melt polyester fiber felt layer, so that the density in the fiber stack is gradually made uniform under the influence of the hot-melt polyester fiber, thereby improving the strength and toughness of the produced jute laminated product.

[0050] S5. After the hot pressing forming is completed, demold and naturally cool to room temperature to obtain a jute laminated product.

[0051] When the hot pressing forming is completed, demold the fiber stack and obtain a jute laminated product after naturally cooling to room temperature. Among them, in this embodiment, the density of the jute laminated product is 80kg / m 3 , and the thickness is 2cm.

[0052] In addition, the hot-pressed and cooled jute laminated product needs to be further processed to be fixed in shape. The specific operation method is as follows: Based on the above-obtained jute laminated product, through a combined cutting machine, the waste materials at the corners can be cut off to obtain a fixed finished product version. At the same time, for the convenience of subsequent use, it is necessary to punch holes at the edges of the jute laminated product through a punching machine. In this embodiment, the diameter of the holes is 1mm. Each hole can be fixed on the surface of an object through a self-locking screw, which is convenient for fixing and not easy to fall off. The front view of the schematic diagram of the hole distribution of the jute laminated product is as Figure 3 shown, and the side view of the schematic diagram of the hole distribution of the jute laminated product is as Figure 4 shown, Figure 3 and Figure 4 are both used to show the fixing method of the self-locking screw.

[0053] During the interconnection process of jute laminated products, in order to facilitate the connection between jute laminated products, it is necessary to perform complementary cutting on the connected jute laminated products. In this embodiment, the length of the connection port is 5 cm, and the length of the embedded bottom edge is 8 cm. Based on the complementary embedding structure, stable connection between jute laminated products can be achieved. The schematic diagram of the complementary embedding connection structure of jute laminated products is as shown in Figure 5 as follows.

[0054] Embodiment 2 Please refer to Figure 1 , which shows the flowchart of the steps of a method for preparing an S-shaped jute fiber three-dimensional structure provided by an embodiment of the present application. The method includes the following steps: S1, based on the finished jute fiber raw material package and the hot-melt polyester fiber raw material package, respectively through unpacking, opening, cotton feeding, carding, and web laying, obtain a jute fiber felt layer and a hot-melt polyester fiber felt layer.

[0055] In this embodiment, the finished S-shaped jute three-dimensional fiber package is prepared into a jute fiber felt layer through a web-forming unit. Specifically: First, use an unpacking machine to open the jute fiber raw material package, so that the jute fiber raw material compacted during transportation is loosened; then, use an opening machine to further disperse the jute fiber raw material to facilitate subsequent web laying operations. Then, through a cotton feeding machine, the processed jute fibers are evenly transported to the carding machine at a stable speed. In the carding machine, the jute fibers are carded by the equipment brush to make them present a single fiber state and are oriented and arranged to form a thinner jute fiber web; finally, use a web laying machine to lay multiple layers of the thinner jute fiber web to make a jute fiber felt layer with a certain thickness and uniformity.

[0056] It should be noted that the web-forming unit in this embodiment includes an unpacking machine, an opening machine, a cotton feeding machine, a carding machine, and a web laying machine, and the purpose is to disperse and lay the finished jute fiber raw material package to form a jute fiber felt layer with uniform texture; the areal density of the jute fiber felt layer in this embodiment is 150 g / m 2 , and the thickness is 2 mm.

[0057] In this embodiment, using the same processing technology as the jute fiber felt layer, replace the jute fiber raw material package with a hot-melt polyester fiber raw material package to prepare a hot-melt polyester fiber felt layer. The purpose of the hot-melt polyester fiber felt layer is that during the subsequent high-temperature hot pressing and shaping process, it can melt at high temperature, so that adjacent jute fiber felt layers are tightly connected, replacing the glue in the traditional process and reducing the risk of formaldehyde emission. Among them, the areal density of the hot-melt polyester fiber layer is 350 g / m 2 , and the thickness is 0.3 mm.

[0058] In addition, the hot-melt polyester fiber selected in this embodiment is required to have a melting point in the range of 180-280°C. In this embodiment, 4080 hot-melt fiber is selected to prepare the hot-melt polyester fiber felt layer. Implementers can choose other existing hot-melt polyester fibers by themselves, such as core-sheath type low-melting-point polyester fiber, ES fiber, core-sheath type polyester stretch yarn, etc.

[0059] S2. Stack the jute fiber felt layer and the hot-melt polyester fiber felt layer crosswise in sequence to obtain a jute layered product fiber stack, denoted as the fiber stack; place the fiber stack in a mold for hot pressing; collect the pressures at each preset position at the bottom of the fiber stack at each moment during the pressurization stage of the hot pressing; and collect the visual images of the fiber stack at each moment at each preset azimuth angle.

[0060] Transport the prepared jute fiber felt layer and the hot-melt polyester fiber felt layer to a cross-lapper. In the cross-lapper, the fiber felt layers on the same conveying chain can be folded and laid to form a laminated pattern of jute fiber felt layer - hot-melt polyester fiber felt layer - jute fiber felt layer - hot-melt polyester fiber felt layer -... - jute fiber felt layer. By repeatedly stacking to reach the preset number of layers or thickness, a jute layered product fiber stack is formed, simply denoted as the fiber stack. A schematic diagram of the jute layered product fiber stack is shown as Figure 2 shown, Figure 2 where 1 is the jute fiber felt layer and 2 represents the hot-melt polyester fiber felt layer.

[0061] Based on the prepared fiber stack, place the fiber stack in a mold through a conveying mesh clamp and perform hot pressing through a hot pressing forming unit. First, preheat the hot pressing forming unit to 230°C for a preheating duration of 15 minutes. After the preheating is completed, perform pressure forming on the fiber stack, set the pressure range to 3 MPa - 15 Mpa, and the hot pressing duration to 30 minutes. Among them, the pressure value is set to 3 MPa at the initial moment of the pressure forming.

[0062] For the remaining process of dynamically adjusting the pressurization process during the hot pressing of the fiber stack, it is implemented according to the exact same steps and parameters as in Embodiment 1 of this application. Among them, the density of the jute layered product in this embodiment is 110 kg / m 3 , and the thickness is 3 cm.

[0063] In addition, the hot-pressed and cooled jute layered product needs to be further processed to be fixed in shape. The specific operation method is as follows: Based on the above-obtained jute layered product, through a combined cutting machine, the waste materials can be cut off to obtain a fixed finished product plate. At the same time, in order to facilitate subsequent use, holes need to be drilled at the edge of the jute layered product through a drilling machine. In this embodiment, the diameter of the holes is 2 mm, and each hole can be fixed to the surface of an object through a self-locking screw, which is convenient for fixing and not easy to fall off.

[0064] During the interconnection process of jute laminated products, in order to facilitate the connection between jute laminated products, it is necessary to perform complementary cutting on the connected jute laminated products. In this embodiment, the length of the connection port is 6 cm, and the length embedded in the bottom edge is 10 cm. Based on the complementary embedding structure, stable connection between jute laminated products can be achieved.

[0065] Example 3 Please refer to Figure 1 , which shows a flowchart of the steps of a method for preparing an S-shaped jute fiber three-dimensional structure provided in an embodiment of the present application. The method includes the following steps: S1, based on the finished jute fiber raw material package and the hot-melt polyester fiber raw material package, respectively through unpacking, opening, cotton feeding, carding, and web laying, obtain a jute fiber felt layer and a hot-melt polyester fiber felt layer.

[0066] In this embodiment, the finished S-shaped jute three-dimensional fiber package is prepared into a jute fiber felt layer through a web-forming unit. Specifically: First, use an unpacking machine to open the jute fiber raw material package, so that the jute fiber raw material compacted during transportation is loosened; then, use an opening machine to further disperse the jute fiber raw material to facilitate subsequent web laying operations. Then, through a cotton feeding machine, the processed jute fiber is evenly transported to the carding machine at a stable speed. In the carding machine, the jute fiber is carded by the equipment brush to make it in a single fiber state and arranged in an oriented manner to form a relatively thin jute fiber web; finally, use a web laying machine to multi-layer lay the relatively thin jute fiber web to make a jute fiber felt layer with a certain thickness and uniformity.

[0067] It should be noted that in this embodiment, the web-forming unit includes an unpacking machine, an opening machine, a cotton feeding machine, a carding machine, and a web laying machine, aiming to disperse and lay the finished jute fiber raw material package to form a jute fiber felt layer with uniform texture; in this embodiment, the areal density of the jute fiber felt layer is 250 g / m 2 , and the thickness is 3 mm.

[0068] In this embodiment, using the same processing technology as the jute fiber felt layer, replace the jute fiber raw material package with a hot-melt polyester fiber raw material package to prepare a hot-melt polyester fiber felt layer. The purpose of the hot-melt polyester fiber felt layer is that during the subsequent high-temperature hot pressing and shaping process, it can be melted at high temperature, so that adjacent jute fiber felt layers are tightly connected, replacing the glue in the traditional process and reducing the risk of formaldehyde emission. Among them, the areal density of the hot-melt polyester fiber layer is 600 g / m 2 , and the thickness is 0.5 mm.

[0069] In addition, the hot-melt polyester fiber selected in this embodiment is required to have a melting point in the range of 180 - 280°C. In this embodiment, 4080 hot-melt fiber is selected to prepare the hot-melt polyester fiber felt layer. Implementers can choose other existing hot-melt polyester fibers by themselves, such as core-sheath type low-melting-point polyester fiber, ES fiber, core-sheath type polyester stretch yarn, etc.

[0070] S2. Stack the jute fiber felt layer and the hot-melt polyester fiber felt layer crosswise in sequence to obtain a jute layered product fiber stack, denoted as the fiber stack; place the fiber stack into a mold for hot pressing; collect the pressures at each preset position at the bottom of the fiber stack at each moment during the pressurization stage of the hot pressing; and collect the visual images of the fiber stack at each moment at each preset azimuth angle.

[0071] Convey the prepared jute fiber felt layer and the hot-melt polyester fiber felt layer to a cross-lapper. In the cross-lapper, the fiber felt layers on the same conveying chain can be folded and lapped, so that the overlapping mode of jute fiber felt layer - hot-melt polyester fiber felt layer - jute fiber felt layer - hot-melt polyester fiber felt layer -... - jute fiber felt layer is presented. Through repeated stacking, the preset number of layers or thickness is achieved, thereby forming a jute layered product fiber stack, simply denoted as the fiber stack. The schematic diagram of the jute layered product fiber stack is as Figure 2 shown, Figure 2 where 1 is the jute fiber felt layer and 2 represents the hot-melt polyester fiber felt layer.

[0072] Based on the prepared fiber stack, place the fiber stack into a mold through a conveying mesh clamp and perform hot pressing through a hot pressing forming unit. First, preheat the hot pressing forming unit to 250°C, and the preheating duration is 20 min. When the preheating is completed, perform pressure forming on the fiber stack. Set the pressure range to 3 MPa - 15 Mpa, and the hot pressing duration is 40 min. Among them, the pressure value at the initial moment of the pressure forming is set to 3 MPa.

[0073] For the remaining process of dynamically adjusting the pressurization process during the hot pressing of the fiber stack, it is implemented according to the exact same steps and parameters as in Embodiment 1 of this application. Among them, the density of the jute layered product in this embodiment is 150 kg / m 3 , and the thickness is 5 cm.

[0074] In addition, the hot-pressed and cooled jute layered product needs to be further processed to be fixed in shape. The specific operation method is as follows: Based on the above-obtained jute layered product, through a combined cutting machine, the corner materials can be cut off to obtain a fixed finished product version. At the same time, in order to facilitate subsequent use, it is necessary to punch holes at the edge of the jute layered product through a punching machine. In this embodiment, the diameter of the holes is 3 mm, and each hole can be fixed on the surface of an object through a self-locking screw, which is convenient for firm fixation and not easy to fall off.

[0075] During the interconnection process of jute laminated products, in order to facilitate the connection between jute laminated products, it is necessary to perform complementary cutting on the connected jute laminated products. In this embodiment, the length of the connection port is 8 cm, and the length embedded in the bottom edge is 12 cm. Based on the complementary embedding structure, stable connection between jute laminated products can be achieved.

[0076] To verify the effectiveness of this application, a comparative example was set up for a comparative experiment. The jute laminated products prepared by the comparative example were used, and the performance of the jute laminated products prepared by this application was verified through testing.

[0077] Comparative Example 1 First, a jute laminated product fiber stack was prepared according to exactly the same steps and parameters as in Example 2 of this application, denoted as the fiber stack. During the hot pressing and forming process, it was first preheated to 230 °C for a preheating duration of 15 min, then under a pressure of 3 Mpa, the pressure was maintained for 14 min, then adjusted to 8 Mpa and the pressure was maintained for 9 min, and then adjusted to 13 Mpa and the pressure was maintained for 7 min. After the hot pressing and forming was completed, it was demolded and naturally cooled to room temperature to obtain the jute laminated product.

[0078] Comparative Example 2 First, a jute laminated product fiber stack was prepared according to exactly the same steps and parameters as in Example 2 of this application, denoted as the fiber stack. During the hot pressing and forming process, it was first preheated to 230 °C for a preheating duration of 15 min, then under a pressure of 5 Mpa, the pressure was maintained for 14 min, then adjusted to 10 Mpa and the pressure was maintained for 9 min, and then adjusted to 15 Mpa and the pressure was maintained for 7 min. After the hot pressing and forming was completed, it was demolded and naturally cooled to room temperature to obtain the jute laminated product. The comparison results of the performance of the jute laminated products in the examples and comparative examples are shown in Table 1.

[0079] Table 1 Comparison Results of the Performance of Jute Laminated Products As can be seen from Table 1, by dynamically adjusting the pressure at each moment during the hot pressing and forming process of the fiber stack, this application can ultimately improve the tensile strength, bending strength, and impact strength of the jute laminated products, and obtain jute laminated products with better performance.

[0080] Based on the same inventive concept as the above method, the embodiment of this application also provides an S-shaped jute fiber three-dimensional structure, which is prepared by applying the steps of any one of the methods for preparing the above S-shaped jute fiber three-dimensional structure.

[0081] It should be noted that the above order of the embodiments of the present application is only for description and does not represent the superiority or inferiority of the embodiments. In addition, the specific embodiments of this specification have been described. Moreover, the processes depicted in the drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0082] Each embodiment in this specification is described in a progressive manner. For the same or similar parts among the embodiments, reference can be made to each other, and the key point of each embodiment is to illustrate the differences from other embodiments.

[0083] The above are only the preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the principles of the present application shall be included within the protection scope of the present application.

Claims

1. A method for preparing an S-shaped jute fiber three-dimensional structure, characterized in that: The method comprises the following steps: Based on the finished jute fiber raw material bales and hot-melt polyester fiber raw material bales, the jute fiber felt layer and the hot-melt polyester fiber felt layer are obtained by opening the bales, loosening, feeding cotton, combing and laying nets respectively; The jute fiber felt layer and the hot-melt polyester fiber felt layer are sequentially cross-stacked to obtain a jute layered product fiber stack, which is recorded as a fiber stack; the fiber stack is placed in a mold for hot pressing; during the pressurization stage of the hot pressing, the pressure at each preset position at the bottom of the fiber stack is collected at each time; and the visual image of the fiber stack at each time is collected at each preset azimuth angle; Analyze the discrete degree and change rate of the pressure at all preset positions at each moment to determine the hot pressing tilt deviation of the fiber stack at each moment; determine the comprehensive deviation value of each preset azimuth angle of the fiber stack at each moment by the degree of deviation of the connection boundary between adjacent jute fiber felt layers in the visual image compared to the horizontal line; Based on the preset weights, the comprehensive deviation values ​​of all preset azimuths at each moment are weighted and fused to obtain the connection density of the fiber stack at each moment; combining the hot pressing tilt deviation with the connection density, the step length of the pressure adjustment in the pressurization stage is corrected to determine the pressure value of the pressurization stage at the next moment of the current moment; After the hot pressing is completed, the jute layered product is demoulded and cooled naturally to room temperature.

2. The method for preparing an S-shaped jute fiber three-dimensional structure according to claim 1, characterized in that: The hot-melt polyester fiber raw material package is 4080 hot-melt fiber with a melting point of 180-280°C.

3. The method for preparing an S-shaped jute fiber three-dimensional structure according to claim 1, characterized in that: The first layer and the last layer of the fiber stack are both jute fiber felt layers; the surface density of the jute fiber felt layer is 50-250g / m 2 , thickness is 1~3mm; the surface density of the hot-melt polyester fiber felt layer is 100~600g / m 2 , thickness is 0.2~0.5mm.

4. The method for preparing an S-shaped jute fiber three-dimensional structure according to claim 1, characterized in that: The hot pressing molding includes a preheating stage and a press molding stage. The temperature of the preheating stage is 200°C to 250°C and the duration is 10 to 20 minutes. The duration of the press molding stage is 20 minutes to 40 minutes.

5. The method for preparing an S-shaped jute fiber three-dimensional structure according to claim 1, characterized in that: The determination of the hot pressing tilt deviation includes: The sum of the gradients of the pressures at all preset positions at each moment is calculated, and the thermal pressure inclination deviation is positively correlated with the discrete degree and the modulus of the sum.

6. The method for preparing an S-shaped jute fiber three-dimensional structure according to claim 1, characterized in that: Determination of the comprehensive deviation value includes: Performing edge detection on the visual images at each preset azimuth at each moment, obtaining a boundary line formed by melting the hot-melt polyester fiber felt layers between adjacent jute fiber felt layers in each visual image, and calculating the sum of the distances between all pixel points on the boundary line and the horizontal line; The comprehensive deviation value is determined based on the sum of the distances of all boundary lines in each visual image.

7. A method for preparing an S-shaped jute fiber three-dimensional structure as claimed in claim 6, characterized in that: The comprehensive deviation value is the average of the sum of the distances of all boundary lines in each visual image.

8. The method for preparing an S-shaped jute fiber three-dimensional structure according to claim 5, characterized in that: The determination of the connection density includes: The weight range of the azimuth angle closest to the direction of the sum value is [0.3, 0.5), the weights of the remaining azimuth angles are equal and the sum of the weights of all azimuth angles is 1; The connection density is the reciprocal of the weighted sum of the comprehensive deviation values ​​of all preset azimuth angles at each moment.

9. The method for preparing an S-shaped jute fiber three-dimensional structure according to claim 4, characterized in that: The determining of the pressure value of the pressurization stage at the next moment of the current moment includes: At each moment, a normalized result of the ratio of the connection density to the hot pressing tilt deviation is calculated, and a ratio of the interval length of the preset pressure range of the press forming stage to the duration of the press forming stage is calculated, which is recorded as a first ratio; The pressure adjustment amount at the next moment after the current moment is the product of the normalization result and the first ratio, and the pressure value of the pressurization stage at the next moment after the current moment is the sum of the pressure value at the current moment and the product; The jute layered product obtained by naturally cooling to room temperature has a density of 80-150 kg / m 3 , thickness is 2~5cm.

10. An S-shaped jute fiber three-dimensional structure, characterized in that: The S-shaped jute fiber three-dimensional structure is prepared by using the method for preparing the S-shaped jute fiber three-dimensional structure according to any one of claims 1 to 9.

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