JP7713871B2 - Manufacturing method of hollow structure plate - Google Patents

Description

The present invention relates to a method for manufacturing a hollow structure board. More specifically, the present invention relates to a method for manufacturing a hollow structure board comprising a hollow structure section containing a thermoplastic resin in which a plurality of hollow sections separated by vertical walls are formed at intervals, and one or more sheets of a surface material and/or skin material containing a thermoplastic resin laminated on at least one surface of the hollow structure section.

Since hollow resin structural panels have excellent impact resistance and compression resistance and are easy to handle, they are used in a wide range of applications, including building materials, packing cases, containers such as returnable boxes, surface protection packaging materials, partition panels, and decorative materials for vehicle interiors (see, for example, Patent Documents 1 and 2).

JP 2008-260309 A JP 2006-1036 A

However, during the manufacturing process of hollow structure boards, there was a problem that folds and wrinkles occurred in the hollow structure parts that form the hollow structure boards, making it difficult to stably produce hollow structure boards continuously.

Therefore, the main objective of the present invention is to provide a method for manufacturing hollow structure panels that can be stably and continuously produced while suppressing the occurrence of breaks and wrinkles.

As a result of intensive experimental investigations, the inventors of the present application focused on the process of creating the hollow structural portion during the manufacturing process of hollow structural panels, and discovered that by removing the non-machined portions during this process, it is possible to prevent the occurrence of creases and wrinkles and ensure stable, continuous production, which led to the completion of the present invention.

That is, the present invention provides a method for manufacturing a hollow structure plate comprising a hollow structure portion containing a thermoplastic resin in which a plurality of hollow portions separated by vertical walls are formed at intervals, and one or more sheets of a surface material and/or skin material containing a thermoplastic resin laminated on at least one side of the hollow structure portion, the method comprising at least a hollow structure portion preparation step of preparing the hollow structure portion from a sheet containing a thermoplastic resin, and a lamination step of laminating the surface material and/or skin material on the hollow structure portion, wherein in the hollow structure portion preparation step, non-processed portions in which a plurality of hollow portions are not formed are removed.
In the present invention, in the hollow structure producing step, the hollow structure may be produced by vacuum forming the sheet.
In the present invention, the removal of the non-processed portion in the hollow structure portion preparation step may be carried out after the sheet in a molten or softened state is solidified.
The present invention may further include a pelletizing step of pelletizing the non-machined portion after removal.
The present invention may further include a winding step of winding up the non-processed portion after removal.
In the present invention, the hollow structure portion may have a basis weight of 300 g/m ² or more.

According to the present invention, a method for manufacturing a hollow structure board can be provided that can suppress the occurrence of breaks and wrinkles and enable stable continuous production.
Note that the effects described here are not necessarily limited to those described herein, and may be any of the effects described in this specification.

1A to 1C are diagrams illustrating a first embodiment of a method for manufacturing a hollow structure plate 1. 4A to 4C are diagrams illustrating a second embodiment of a method for manufacturing a hollow structure plate 1. 13A to 13C are diagrams illustrating a third embodiment of a method for manufacturing a hollow structure plate 1. FIG. 1A is a diagram showing a schematic diagram of a first embodiment of a hollow structure plate 1, and FIG. 1B is a diagram showing a schematic diagram of a second embodiment of the hollow structure plate 1. 1C is a diagram showing a schematic diagram of a third embodiment of the hollow structure plate 1, and FIG. 1D is a diagram showing a schematic diagram of a fourth embodiment of the hollow structure plate 1. FIG. 10E is a diagram showing a schematic diagram of a hollow structure plate 1 according to a fifth embodiment. S is a schematic diagram showing an example of an embodiment of a hollow structure portion 11 in a hollow structure plate manufacturing process, T is a schematic diagram showing the state viewed from the direction of the arrow in S, and U is a schematic diagram showing the end face of the P-P line in T.

1. Hollow structure plate 1
The hollow structure board 1 manufactured by the manufacturing method according to the present invention will be described in detail below.
The hollow structure board 1 comprises a hollow structure portion 11 and a surface material and/or a skin material (12, 13).

The hollow structure board 1 manufactured by the manufacturing method according to the present invention has good surface properties and appearance, and is less prone to breaks and wrinkles, as shown in the examples described below.

The basis weight of the hollow structure board 1 is not particularly limited, but is preferably 200 g/m ² or more and 6000 g/m ² or less, and more preferably 300 g/m ² or more and 4000 g/m ² or less. This allows the hollow structure board 1 to be lightweight.

The end faces of the hollow structure plate 1 can be machined into any shape. Specifically, for example, the end faces can be left uncut, machined into a C-shape, sealed to form a vertical end face, or sealed into an R-shape. Furthermore, in the present invention, an edge material or the like can be attached to the end faces to impart functionality to the end faces of the hollow structure plate 1.

(1) Hollow structure part 11
The hollow structure 11 contains a thermoplastic resin in which a plurality of hollow portions 111 separated by vertical walls are formed at intervals. Moreover, one or more sheets of a surface material and/or skin material (12, 13) containing a thermoplastic resin are laminated on at least one surface of the hollow structure 11. Note that, in the present invention, a small gap may be partially formed between the hollow structure 11 and the surface material and/or skin material (12, 13). Also, in the present invention, the number of sheets of the surface material and/or skin material (12, 13) laminated on the hollow structure 11 is not particularly limited.

The angle (inclination angle) θ1 (see U in FIG. 7) between the imaginary horizontal plane and the vertical wall in the hollow structure 11 is not particularly limited, but it is preferable for the vertical wall to have an inclination angle in order to obtain sufficient strength when a load is applied from the outside of the hollow structure plate 1. If the vertical wall has an inclination angle, it is preferable that the inclination angle θ1 is 45° or more. By making the inclination angle θ1 45° or more, even more sufficient strength can be obtained. In addition, it is preferable that the inclination angle θ1 is less than 80°. By making the inclination angle θ1 less than 80°, it is possible to prevent the thickness of the hollow structure 11 from becoming too thin when the hollow structure 11 is vacuum-formed, and also to prevent the vertical wall from becoming a film, thereby obtaining sufficient strength.

Moreover, it is more preferable that the inclination angle θ1 is greater than or equal to 50° and less than 75°. This increases the rigidity of the hollow structure board 1. It also prevents deformation due to buckling, etc., and improves the shape retention of the hollow structure board 1. Note that in the hollow structure board 1, the inclination angle θ1 does not have to be constant at all times, and the vertical wall may have an asymmetric shape with respect to the central axis.

The height h of the vertical wall (see U in Figure 7) is not particularly limited, but is preferably 1 mm or more. By making the height h of the vertical wall 1 mm or more, a hollow structure board 1 with high rigidity can be obtained. In addition, the height h of the vertical wall is preferably 50 mm or less. By making the height h of the vertical wall 50 mm or less, when a hollow convex portion described later is used as the hollow portion 111, it is possible to prevent the side wall portion of the convex portion from becoming too thin, and to prevent deformation of the hollow structure portion 11.

The thickness of the vertical wall is not particularly limited, but is preferably 0.1 mm or more. By making the thickness of the vertical wall 0.1 mm or more, deformation such as buckling can be prevented, and the shape retention of the hollow structure plate 1 can be improved. In addition, in the present invention, steps or waves may be provided in part or all of the vertical wall.

The material of the hollow structure 11 is a thermoplastic resin. If necessary, an inorganic substance may be added to the thermoplastic resin to improve moldability and mechanical properties. When an inorganic substance is contained, it can be appropriately mixed into the thermoplastic resin at a desired content ratio (for example, 0.5 mass% or more) by a conventionally known method. Furthermore, in the present invention, a dispersant, an antioxidant, an ultraviolet absorber, an antistatic agent, a conductive agent, an antibacterial agent, a flame retardant, a light stabilizer, a lubricant, etc. may be appropriately added to the thermoplastic resin forming the hollow structure 11 or the surface material described later in order to improve flame retardancy, conductivity, wettability, slipperiness, weather resistance, etc.

Examples of the thermoplastic resin include polyethylene, polypropylene, polystyrene, polyurethane, polycarbonate, polymethyl methacrylate, polyacetal, etc. In the present invention, from the viewpoints of cost, moldability, weight, and physical properties, polyolefin resins such as low-density polyethylene (LDPE), high-density polyethylene (HDPE), linear low-density polyethylene, very low-density polyethylene, polypropylene homopolymer, polypropylene random copolymer, and polypropylene block copolymer are particularly preferred. In order to obtain high rigidity, engineering plastics such as ABS resin and polycarbonate can also be used. In addition, the resin may be appropriately colored using a coloring agent such as a pigment, if necessary.

Examples of the inorganic substances include silicates, sulfates, carbonates, phosphates, borates, oxides, or hydrates thereof, inorganic fibers, etc., of magnesium, aluminum, calcium, titanium, iron, zinc, etc. Specific examples include clays such as talc and kaolin, calcium carbonate, magnesium carbonate, zinc oxide, titanium oxide, silica, alumina, aluminum hydroxide, magnesium hydroxide, aluminum silicate, magnesium silicate, calcium silicate, aluminum sulfate, magnesium sulfate, calcium sulfate, magnesium phosphate, barium sulfate, silica sand, carbon black, zeolite, molybdenum, diatomaceous earth, sericite, shirasu, calcium sulfite, sodium sulfate, potassium titanate, bentonite, wollastonite, dolomite, graphite, glass fiber, microglass, carbon fiber, ceramic fiber, rock wool, etc. Note that these inorganic substances may be prepared by a synthetic method or may be naturally derived. In addition, one or more of these inorganic substances may be selected and used.

The hollow structure 11 and the surface material and/or skin material (12, 13) described below may be made of the same material, or may be made of different materials as long as they are heat-sealable.

The specific structure of the hollow structure 11 is not particularly limited, and examples thereof include a structure made of one thermoplastic resin sheet having a plurality of hollow protrusions formed as the hollow portion 111 on at least one surface (see A to C in Figs. 4 and 5), a structure made of a thermoplastic resin sheet having a plurality of honeycomb-structured hollow portions 111 formed thereon (see D in Fig. 5), or a structure made of two thermoplastic resin sheets having a plurality of hollow protrusions formed as the hollow portion 111 on at least one surface (see E in Fig. 6). In the present invention, among these, a structure made of one or two thermoplastic resin sheets having a plurality of hollow protrusions formed as the hollow portion 111 on at least one surface is particularly preferred. In addition, in the present invention, a structure in which a flow path exists in a part of the hollow structure 11 can also be adopted. In this case, the shape of the flow path, the cross-sectional structure of the flow path, the formation direction of the flow path, etc. are not particularly limited.

The specific shape of the convex portion 111 is not particularly limited as long as it has at least the upper surface portion 112 and the opening portion 113 as shown in U of FIG. 7, and can be freely designed. Specifically, it can be designed into various shapes such as a truncated cone shape, an elliptical truncated cone shape, a triangular truncated cone shape, a square truncated cone shape, a pentagonal truncated cone shape, or a polygonal truncated cone shape, as well as a cylindrical shape, an elliptical truncated cone shape, a polygonal prism shape, a polygonal prism shape, and a polygonal prism shape. In addition, the shapes of the multiple convex portions 111 may all be the same shape, or may be a combination of the above-mentioned shapes. Furthermore, it is also possible to provide steps or waves on the side surfaces, upper surface portions 112, or opening portions 113 of some or all of the convex portions 111.

In the present invention, when the surface material and/or skin material (12, 13) described below is laminated to the hollow structure 11, the corners of the polygonal truncated pyramid shape, polygonal column shape, etc. may be designed to be rounded in order to reduce the number of starting points and improve the peel strength from the surface material and/or skin material (12, 13).

As the shape of the convex portion 111, it is preferable that it is any one or more shapes selected from the group consisting of a truncated cone shape, an elliptical truncated cone shape, and a truncated polygonal pyramid shape among the above-mentioned shapes. This not only makes it possible to simplify the design in the manufacturing process, but also reduces the manufacturing cost of the mold when the convex portion 111 is formed using a mold. Furthermore, as the shape of the convex portion 111, it is preferable that it is a shape having at least a taper in a part as shown by U in FIG. 7, and specifically, it is preferable that it is a truncated cone shape and/or an elliptical truncated cone shape, and it is particularly preferable that it is an elliptical truncated cone shape. This makes it possible to improve the bending rigidity of the hollow structure plate 1 and maintain the compressive strength.

When the convex portion 111 is designed to have a truncated cone shape and/or an elliptical truncated cone shape, the diameter or major axis length of the upper surface portion 112 is not particularly limited, but is preferably set to 1 mm or more and 10 mm or less. This allows the compression strength of the hollow structure plate 1 in the thickness direction to be improved. In addition, the diameter or major axis length of the opening 113 is not particularly limited, but is preferably set to 3 mm or more and 20 mm or less. This allows the compression strength of the hollow structure plate 1 in the thickness direction to be improved.

The arrangement of the multiple protrusions 111 is not particularly limited, and may be arranged in a square lattice, staggered, or irregular pattern. In the present invention, among the above, it is particularly preferable to arrange them in a square lattice or staggered pattern. The arrangement of the multiple protrusions 111 also includes a pattern in which adjacent protrusions 111 are arranged alternately when viewed along a predetermined reference direction.

When the protrusions 111 are arranged in a staggered pattern, the angle θ2 (see T in FIG. 7) between the line connecting the centers of the horizontal protrusions 111 and the line connecting the centers of the diagonal protrusions 111 is not particularly limited, but it is preferable to set θ2 = approximately 60°. This can improve the rigidity of the hollow structure plate 1. Note that "square lattice pattern" refers to an arrangement where θ2 = approximately 90°.

The shortest distance L between the openings 113 of the convex portions 111 (see T in FIG. 7) is not particularly limited, but is preferably 0.2 mm or more and 8 mm or less. By making the shortest distance L 0.2 mm or more, it is possible to prevent the thickness of the liner portion (the portion where the convex portions 111 are not present when the convex portions 111 are viewed from a certain direction) from becoming too thin, thereby avoiding a decrease in compressive strength. In addition, by making the shortest distance L 8 mm or less, it is possible to prevent the distance between the convex portions 111 from becoming too long and the number of convex portions 111 per unit area from decreasing too much, thereby maintaining the bending rigidity of the hollow structure plate 1 at a certain level or more. Note that in the present invention, the shortest distance L does not have to be constant at all times.

In the present invention, the structure consisting of a single thermoplastic resin sheet having a plurality of hollow protrusions formed on at least one surface thereof can be specifically, for example, a structure consisting of a single thermoplastic resin sheet having a plurality of elliptical truncated cone-shaped protrusions formed on one surface thereof, as shown in FIG. 1. By adopting this structure, it is possible to provide a hollow structure plate 1 that has excellent workability while maintaining planar compressive strength.

The lower limit of the basis weight of the hollow structure 11 is not particularly limited, but is preferably 300 g/ ^m2 or more. By making the basis weight 300 g/m2 or ^more , it is possible to further suppress the occurrence of folds and wrinkles in the hollow structure 11. In addition, the upper limit of the basis weight of the hollow structure 11 is not particularly limited, but is preferably 1500 g/m2 or ^less . By making the basis weight 1500 g/m2 or ^less , it is possible to reduce the weight of the hollow structure board 1.

The thickness of the hollow structure portion 11 is not particularly limited, but is preferably 1.5 mm or more and 55 mm or less. By making it 1.5 mm or more, the thickness of the hollow structure plate 1 can be prevented from becoming too thin, and a hollow structure plate 1 that maintains bending rigidity can be produced. Furthermore, by making it 55 mm or less, the height of the vertical wall in the hollow structure portion 11 can be controlled, and when the hollow convex portion described above is used as the hollow portion 111, the thickness of the side wall can be prevented from becoming too thin due to drafting, and a hollow structure plate 1 that is less likely to undergo deformation such as buckling can be produced.

(2) Surface material and/or skin material (12, 13)
One or more sheets of the surface material and/or skin material (12, 13) are laminated on at least one surface of the hollow structure portion 11. The surface material contains a thermoplastic resin. In the present invention, a skin material may be laminated on the surface material. In addition, when there are multiple surface materials and/or skin materials (12, 13), the thicknesses, basis weights, etc. of the multiple surface materials and/or skin materials (12, 13) may all be the same or different.

In Figures 4 to 6, for convenience, the surface material and/or skin material laminated on the upper side of the hollow portion (convex portion) 111 is referred to as the "upper surface material and/or skin material 12," and the surface material and/or skin material laminated on the lower side (opening side) of the hollow portion (convex portion) 111 is referred to as the "lower surface material and/or skin material 13," but in the actual product, the hollow structure board 1, these distinctions do not apply.

The surface material is, for example, a thermoplastic resin. If necessary, the surface material may contain an inorganic substance to improve moldability and mechanical properties. When the surface material contains an inorganic substance, the inorganic substance can be appropriately mixed into the thermoplastic resin at a desired content ratio (for example, 0.5 mass% or more) by a conventionally known method.
The thermoplastic resin and inorganic material are the same as those described above, and therefore a description thereof will be omitted here.
As the thermoplastic resin, among the above-mentioned ones, polyolefin resin is particularly preferable. In order to obtain high rigidity, engineering plastics such as ABS resin and polycarbonate can also be used. In addition, the resin may be appropriately colored using a coloring agent such as a pigment, if necessary.

The thickness of the surface material is not particularly limited, but it is preferably 0.1 mm or more and 2.0 mm or less. By making it 0.1 mm or more, the rigidity of the hollow structure board 1 can be maintained. Furthermore, by making it 2.0 mm or less, costs can be reduced.

The basis weight of the surface material is not particularly limited, but is preferably 100 g/ ^m2 or more and 2000 g/m2 or ^less . By setting the basis weight to 100 g/ ^m2 or more, it is possible to prevent the surface material from becoming too thin and breaking when the surface material is attached to the hollow structure portion 11. In addition, by setting the basis weight to 2000 g/ ^m2 or less, it is possible to reduce the weight of the hollow structure board 1.

The skin material can be laminated to the hollow structure 11 and/or the surface material, but is preferably laminated to the surface material. By laminating the skin material, it is possible to impart properties to the hollow structure board 1 according to various applications, such as design, sound absorption properties, and heat insulation properties.

The material of the skin is not particularly limited, and any material that can be used as a skin for a hollow structural board can be appropriately selected and used depending on the intended use. Specific examples include thermoplastic resin sheets, resin woven fabrics, nonwoven fabrics, braided fabrics, knitted fabrics, metal sheets made of stainless steel, aluminum, copper, etc., organic or inorganic porous sheets, decorative sheets, etc.

2. Manufacturing Method of the Hollow Structure Plate 1 Figures 1 to 3 are diagrams that show schematic diagrams of the respective embodiments of the manufacturing method according to the present invention.
The manufacturing method according to the present invention is a method for manufacturing the above-mentioned hollow structure plate 1, and includes at least a hollow structure part manufacturing process and a lamination process. In addition, a winding process, a pelletizing process, a sizing process, etc. may be performed as necessary. Each process will be described in detail below with reference to the drawings.

(1) Hollow Structure Producing Step The hollow structure producing step is a step of producing the hollow structure 11 from a sheet containing a thermoplastic resin.

A method for producing the hollow structure 11 from a sheet containing a thermoplastic resin includes, for example, vacuum forming the sheet. More specifically, as shown in Figures 1 and 3, a vacuum forming device is used in which one or more forming rollers 101 with a plurality of convex pins protruding from the surface are arranged, and a molten or softened thermoplastic resin sheet extruded from an extruder equipped with a T-die at the tip is injected into the grooves of the forming roller 101, and is molded by binding it to the forming roller 101. Each forming roller 101 is installed in a vacuum chamber, and the vacuum chamber is provided with a suction hole for suctioning and holding the hollow structure 11.

After the hollow portion 111 is formed, it is taken up by the take-up rollers 102 as shown in Figures 1 to 3, for example, while retaining the non-processed portion (see the X parts of S and T in Figure 7). By providing the take-up rollers 102, it is possible to improve formability.

In the present invention, the portion where the non-processed portion is formed is not particularly limited, but examples include both end portions in the TD direction (direction approximately perpendicular to the MD direction) that are continuous with the MD direction (machine direction). This non-processed portion acts as a seal at the end, particularly when performing vacuum molding, and by maintaining the reduced pressure and reducing pressure fluctuations, a hollow structure portion 11 with a stable shape can be obtained.

Another method for producing the hollow structure 11 from a sheet containing thermoplastic resin is, for example, a method using a mold. Specifically, as shown in FIG. 2, a molten or softened thermoplastic resin sheet extruded from an extruder equipped with a T-die at the tip is injected into the grooves of a pair of molds 106 having a desired surface shape, and is then pressed from both sides to form the shape. Even in this case, the non-processed parts act as seals at the ends, so that a hollow structure 11 with a stable shape can be obtained.

However, if there is a non-processed portion, the tension during the process becomes non-uniform, which causes creases and wrinkles in the hollow structure portion 11, making it difficult to stably and continuously manufacture hollow structure boards. Creases and wrinkles tend to occur in the MD direction in particular, and are more pronounced when the rigidity of the hollow structure portion 11 is low (for example, when the basis weight of the hollow structure portion 11 is 500 g/ ^m2 or less). Furthermore, when a sizing process described later is performed, the increase in process resistance is more pronounced.

In this specification, "folds" and "wrinkles" refer to those that occur in the hollow structure 11 and cause continuous or intermittent dents, protrusions, grooves, streaks, etc. that are reflected or appear on the surface of the hollow structure board 1 after the surface material and/or skin material (12, 13) are attached.

In contrast, the present invention is characterized in that the non-machined portions where multiple hollow portions 111 are not formed are removed during the hollow structure manufacturing process. This prevents uneven tension during the process caused by the presence of non-machined portions, and suppresses the occurrence of creases and wrinkles.

The method for removing the non-machined portion is not particularly limited, and either a contact or non-contact method may be used. In the case of a contact method, examples include cutting with a blade such as a cutter blade, mechanical shearing, and press shearing. In the case of a non-contact method, examples include cutting by laser irradiation or laser heating. In the present invention, among these, cutting with a blade such as a cutter blade is particularly preferred from the viewpoint of cost and ease of handling.

When cutting with a blade, the material from which the blade is made is not particularly limited, and conventionally known materials such as SK (carbon tool steel), stainless steel, titanium, and ceramics can be used. The thickness of the blade is also not particularly limited, but can be, for example, 0.3 mm to 5 mm. If the thickness of the blade is less than 0.3 mm, the blade is prone to breaking, and if the thickness of the blade exceeds 5 mm, the cutting resistance increases and the installation space increases. The blade can be fixed at a predetermined position, and may be inserted into the hollow structure 11 at the fixed position.

In this process, the timing of removing the non-processed portion is not particularly limited, but it is preferable to remove the non-processed portion after the molten or softened thermoplastic resin sheet has solidified. If the sheet is not sufficiently solidified, this may lead to poor removal or molding. Specifically, it is preferable to remove the non-processed portion relatively early after the sheet is molded into the hollow structure 11 and solidified. More specifically, it is preferable to install the blade 103 at a position immediately after the take-up roller 102 of the hollow structure 11 (for example, a position 1 m or less from the center of the take-up roller) as shown in Figures 1 to 3. The closer the timing of removing the non-processed portion is to the next lamination process, the more difficult it is to eliminate the effects of folds and wrinkles in the hollow structure 11 before removing the non-processed portion.

(2) Lamination Step The lamination step is a step of laminating the surface material and/or skin material (12, 13) onto the hollow structure portion 11 produced in the hollow structure portion production step.

The lamination process can be carried out by a conventionally known method. For example, as shown in Figures 1 to 3, a surface material and/or skin material (12, 13) made of a molten or softened thermoplastic resin sheet extruded from an extruder equipped with a T-die at the tip is heated and pressed onto both sides of the hollow structure portion 11 by a flat roller 105.

(3) Winding step The winding step is a step of winding up the non-processed portion after removal. Although the winding step is not essential in the manufacturing method according to the present invention, by performing the winding step, the removed non-processed portion can be efficiently collected, which also leads to space saving.

The method for winding up the non-machined portion is not particularly limited, but an example is a method of winding up the non-machined portion around one or more rotating rollers 104. The installation position of the rotating roller is not particularly limited, but it is preferable to install it on the upper surface side of the take-up roller 102, as shown in Figures 1 to 3. In this case, the surface of the non-machined portion being wound up and the surface of the hollow structure portion 11 form an angle of approximately 90°. This allows space to be saved.

(4) Pelletizing process The pelletizing process is a process of pelletizing the non-processed part after removal. In this specification, "pelletizing" refers to processing the non-processed part into a pellet shape or cutting it to a pellet size. When a winding process is performed, the pelletizing process is preferably performed after the winding process. In the manufacturing method according to the present invention, the pelletizing process is not essential, but by performing the pelletizing process, the removed non-processed part can be reused, which can contribute to solving the waste plastic problem and achieving the SDGs.

The pelletizing method is not particularly limited, and can be performed by a conventional method using a pelletizer, etc.

(5) Sizing Step The sizing step is a step in which the surface material and/or skin material (12, 13) is brought into close contact with at least one sizing former 107 as shown in Fig. 3 before the surface material and/or skin material (12, 13) solidifies. In the manufacturing method according to the present invention, the sizing step is not essential, but performing the sizing step can improve the surface smoothness of the hollow structure board 1. Furthermore, in the present invention, it is possible to suppress breaks and wrinkles that are likely to occur when the sizing step is performed.

In this specification, the term "sizing former" refers to a mold used in extrusion molding or the like for the purpose of obtaining surface smoothness before the extrudate is completely cooled. The sizing former used in this process can be a conventionally known one, and there are no particular limitations on the material, performance, shape, size, etc. The sizing former is usually made of a material with high thermal conductivity (e.g., aluminum, iron, etc.), and the temperature can be adjusted by contacting it with a refrigerant or heat transfer medium, which allows efficient heat exchange with the material in contact with the sizing former (in this invention, the surface material and/or skin material (12, 13)).

The method for adhering the surface material and/or skin material (12, 13) to the sizing former is not particularly limited, and can be performed by a conventionally known method such as vacuum suction or reduced pressure suction. When adhering by reduced pressure suction, the negative pressure is not particularly limited, but is preferably 5 Kpa or more and 80 Kpa or less.

In the present invention, if necessary, after the surface material and/or skin material (12, 13) are brought into close contact with the sizing former, the temperature can be controlled using a temperature-controlled pressing roller (not shown).

The present invention will now be described in further detail with reference to examples.
The embodiment described below is merely a representative example of the present invention, and the scope of the present invention should not be construed as being narrow.

First, hollow structure plates of Examples 1 to 12 shown in Tables 1 and 2 below and Comparative Examples 1 to 12 shown in Tables 3 and 4 below were produced. The shapes of each hollow structure plate are shown in Tables 1 to 4 below. The hollow structure plates of Examples 1 to 12 were produced based on the manufacturing method shown in Figure 1 when a sizing former was not used, and were produced based on the manufacturing method shown in Figure 3 when a sizing former was used. In addition, the hollow structure plates of Comparative Examples 1 to 12 were produced based on the same manufacturing method as the manufacturing method shown in Figure 1 except that the non-machined portion was not removed in the hollow structure portion production process when a sizing former was not used, and were produced based on the same manufacturing method as the manufacturing method shown in Figure 3 except that the non-machined portion was not removed in the hollow structure portion production process when a sizing former was used.
In Tables 1 to 4 below, "PP" stands for polypropylene, and "highly inorganic filled PP" stands for polypropylene containing 4% by mass of talc, an inorganic substance, in the hollow structure and 20% by mass in the surface material.

Next, the following evaluations were carried out for each hollow structure panel. The evaluation results are also shown in Tables 1 to 4 above.

[Evaluation of creases]
Five pieces of each hollow structure plate were cut into pieces with a length of about 1 m and a width of about 1.3 m. Each piece was then visually checked for creases. If there was even one crease, it was judged as "creased." Even if the degree of crease was slight, it was judged as "creased."
The evaluation criteria for creases are as follows:
A: No breaks were found in any of the hollow structure panels.
B: A break was found in one hollow structure board.
C: Two hollow structure plates were found to be broken.
D: Three hollow structure plates were found to be broken.
E: There were four hollow structure panels in which breaks were found.
F: Cracks were found in all hollow structure panels.

[Wrinkle evaluation]
Five pieces of each hollow structure plate were cut into pieces with a length of about 1 m and a width of about 1.3 m. Each piece was then visually checked for wrinkles. If there was even one wrinkle, it was judged as "wrinkled." Even if the degree of wrinkles was slight, it was judged as "wrinkled."
The criteria for evaluating wrinkles are as follows:
A: Wrinkles were not found in any of the hollow structure boards.
B: Wrinkles were found in one hollow structure board.
C: Wrinkles were found in two hollow structure boards.
D: Wrinkles were found in three hollow structure boards.
E: Wrinkles were found in four hollow structure boards.
F: Wrinkles were found in all hollow structure panels.

[comprehensive evaluation]
When both the folding evaluation and the wrinkle evaluation were B or higher, the sample was judged as "passed", and all other cases were judged as "failed".

It was found that the hollow structure boards of Examples 1 to 12 were less susceptible to breakage and wrinkles than the hollow structure boards of Comparative Examples 1 to 12.
Therefore, it was found that by removing non-processed portions in which multiple hollow portions are not formed in the hollow structure manufacturing process, it is possible to provide a method for manufacturing hollow structure panels that suppresses the occurrence of breaks and wrinkles and enables stable continuous production.

The present invention provides a method for manufacturing hollow structure boards that suppresses the occurrence of breaks and wrinkles and allows for stable, continuous production. Hollow structure boards manufactured by this manufacturing method are useful in a wide range of fields, including building materials, packaging cases, containers such as returnable boxes, surface protection packaging materials, partition boards, and decorative materials that make up the interiors of vehicles.

1: Hollow structure plate 11: Hollow structure portion 111: Hollow portion (convex portion)
112: Upper surface portion 113: Opening 12: Upper surface material and/or skin material 13: Lower surface material and/or skin material 101: Forming roller 102: Take-off roller 103: Blade 104: Rotating roller 105: Flat roller 106: Mold 107: Sizing former h: Height of vertical wall L: Shortest distance between openings 113 of convex portion 111 X: Non-processed portion θ1: Inclined angle θ2: Angle between a line connecting the centers of convex portions 111 in the horizontal direction and a line connecting the centers of convex portions 111 in the diagonal direction

Claims (6)

A method for manufacturing a hollow structure plate comprising: a hollow structure portion containing a thermoplastic resin in which a plurality of hollow portions separated by vertical walls are formed at intervals; and one or more sheets of a surface material and/or a skin material containing a thermoplastic resin laminated on at least one surface of the hollow structure portion,
a hollow structure preparation step of preparing the hollow structure from a sheet containing a thermoplastic resin;
a lamination step of laminating the surface material and/or skin material on the hollow structure portion;
and
In the hollow structure portion creating step, a non-processed portion where multiple hollow portions are not formed is removed. The method for manufacturing a hollow structure plate according to claim 1, wherein the hollow structure manufacturing process involves vacuum forming the sheet to produce the hollow structure. The method for manufacturing a hollow structure plate according to claim 1 or 2, wherein the removal of the non-machined portion in the hollow structure preparation process is performed after the sheet in a molten or softened state has solidified. The method for manufacturing a hollow structure plate according to any one of claims 1 to 3 further includes a pelletizing step for pelletizing the non-machined portion after removal. The method for manufacturing a hollow structure plate according to any one of claims 1 to 4, further comprising a winding step for winding up the non-machined portion after removal. The method for manufacturing a hollow structure board according to claim 1 , wherein the hollow structure portion has a basis weight of 300 g/m ² or more.