Patent Application
20200086549
The present invention relates to a three-dimensional object obtained by shaping a sheet-like resin, and a method for manufacturing the same.
Planar sheet or film members molded from thermoplastic resins such as polyvinyl chloride (PVC) and polyethylene terephthalate (PET) are stretched or folded by press forming or vacuum forming to manufacture desired three-dimensional containers and the like (for example, refer to JP 6166304 B2 and JP 2016-198969 A). In addition, due to their transparency and texture, such sheet or film members are formed in a box shape for use as packaging containers and the like (for example, refer to JP 5963930 B1).
Those sheets are molded by molding dies tailored to the molded shapes. Thus, in trial production and small-lot production, the manufacturing costs will be high for the volume of manufacture. In addition, it takes a lot of time from the design to the completion including the period for manufacturing the mold, so repeating the specification change in the trial manufacture will increase the time and cost. The folding process is also possible by a manual operation using a ruler or the like. However, high accuracy is required because, once the sheet is bent, the fold remains on the sheet, so redoing is impossible. In addition, it is difficult to stop the fold at a desired position in the sheet without folding to the end of the sheet or to form a curved fold line in the sheet. Furthermore, a high-rigidity sheet due to a certain thickness or the like tends to crack when bent. Even if it can be bent once, when the sheet is refolded such that a mountain fold is turned into a valley fold, the sheet may become broken at the fold.
An object of the present invention is to provide a three-dimensional object in which a sheet-like resin is formed into a desired shape and which can be easily manufactured and is suitable for small-volume production and trial production, and a method for manufacturing the same.
In order to solve the above problems, a three-dimensional object according to the present invention is a three-dimensional object formed by bending and deforming a sheet-like base material made of a thermoplastic resin at a ridge line. A surface of the base material bent and oriented outward at least at the ridge line is covered with a thermal expansion layer that expands when heated to a thermal deformation temperature of the thermoplastic resin or a higher temperature. The thermal expansion layer is expanded at the ridge line.
A three-dimensional object manufacturing method according to the present invention is a method for manufacturing a three-dimensional object in which a sheet-like base material made of a thermoplastic resin is bent and deformed at a ridge line. The three-dimensional object manufacturing method includes: a thermal expansion layer formation step of forming a thermal expansion layer to expand when heated to a predetermined temperature range on a sheet-like base material made of a thermoplastic resin of which a thermal deformation temperature is equal to or lower than the predetermined temperature range; a printing step of drawing a line on at least one surface by a printing material that contains a photothermal conversion component to convert absorbed light into heat and emit the heat; and a light irradiation step of irradiating the surface on which the line is drawn with light to be converted into heat by the photothermal conversion component. In the light irradiation step, the thermal expansion layer immediately below the line is expanded and the base material is bent at the line such that the expanded thermal expansion layer faces outside. Alternatively, in the three-dimensional object manufacturing method according to the present invention, the base material is further configured to transmit light. The three-dimensional object manufacturing method includes: a printing step of drawing a line by the printing material; a thermal expansion layer formation step of forming a thermal expansion layer on one surface of the base material; and a light irradiation step of irradiating the base material with the light. In the printing step, the line is drawn on the one surface of the base material or the base material side of the thermal expansion layer.
According to the three-dimensional object of the present invention, a packaging container or the like of a desired shape can be easily obtained from a thermoplastic resin sheet. According to the three-dimensional object manufacturing method of the present invention, a thermoplastic resin sheet can be easily formed into a desired three-dimensional shape without preparing a mold.
Hereinafter, modes for carrying out the present invention will be described in detail with reference to the drawings. However, the modes described below are merely intended to exemplify wires and the like for embodying technical ideas of the embodiments but are not intended to limit the technical ideas of the embodiments to those described below. The members illustrated in the drawings may be exaggerated in size, positional relationship, and the like, for the sake of clarity, and may be simplified in shape. Further, in the following descriptions, the same or similar members and steps are denoted by the same reference numerals, and duplicated descriptions thereof will be appropriately omitted.
Structures of three-dimensional objects according to the present invention will be described with reference to
[Sheet Formed Article]
As illustrated in
As illustrated in
Each of the sheet formed articles 11 and 12 (hereinafter, called as appropriate collectively sheet formed article 11) according to the first embodiment of the present invention includes a base material 1 and a thermal expansion layer 2 laminated on a surface of the base material 1 outside ridge lines, and the thermal expansion layer 2 is swollen at the ridge lines as illustrated in
[Thermal Expansion Layer-Coated Resin Sheet]
A configuration of the thermal expansion layer-coated resin sheet 10 before the formation of the sheet formed article 11 will be described below with reference to
(Base Material)
The base material 1 is a main element of the sheet formed article 11, and is a sheet-like member having rigidity for holding the shape of the sheet formed article 11 as a box and having flexibility. The base material 1 is flat before the formation of the sheet formed article 11 (the thermal expansion layer-coated resin sheet 10). The sheet formed article 11 has creases for mountain folds (or valley folds) at all the ridge lines. The base material 1 is made of a thermoplastic resin, specifically, polyvinyl chloride (PVC), polyethylene terephthalate (PET), polypropylene (PP) and the like. The base material 1 is formed into a non-oriented film or a biaxially oriented film. The base material 1 may further contain a colorant such as a pigment and be tinted in a desired color. The base material 1 has a thickness to have the rigidity described above. On the other hand, however, as the thickness becomes smaller, the base material 1 becomes more difficult to bend and becomes difficult to form a curved surface with a reduction in flexibility. The base material 1 preferably has a thickness of 0.2 to 0.5 mm before formation depending on the material so as to have appropriate rigidity and flexibility.
(Thermal Expansion Layer)
The thermal expansion layer 2 is a member that expands when heated to a predetermined temperature range (expansion temperature range). As described later, the thermal expansion layer 2 locally expands in a linear manner in the manufacturing process of the sheet formed article 11 to apply a load to the base material 1 to be bent by plastic deformation. The thermal expansion layer 2 is a film that contains thermal expansion microcapsules applied to a known thermal expansion sheet, and is formed to a uniform thickness to before the formation of the sheet formed article 11 (the thermal expansion layer-coated resin sheet 10) with a thermoplastic resin as a binder. The thermal expansion layer 2 may further be tinted in a desired color by containing a white pigment such as titanium oxide or a pigment other than black (not containing carbon black). The microcapsules form a shell of a thermoplastic resin and contain a volatile solvent. When heated to reach an expansion temperature range, the microcapsules expand to a size corresponding to the heating temperature and heating time. The thermal expansion layer 2 expands up to about 10 times the volume before expansion depending on the composition of the microcapsules and the like. For the thermal expansion layer 2, the lower limit value (expansion start temperature TEs) of the expansion temperature range can be designed as appropriate from a low temperature of about 70° C. to a high temperature close to 300° C. by selecting a thermoplastic resin and volatile solvent in the microcapsules.
In the present invention, thermal deformation temperature TD of the thermoplastic resin constituting the base material 1 is designed to be a temperature within the expansion temperature range of the thermal expansion layer 2 or lower. In the present embodiment, the thermal deformation temperature TD is preferably equal to or lower than the expansion start temperature TEs of the thermal expansion layer 2, and more preferably is less than the expansion start temperature TEs. The thermal deformation temperature TD of the thermoplastic resin is preferably a temperature at a low load. However, if the expansion start temperature TEs of the thermal expansion layer 2 is too high relative to the thermal deformation temperature TD of the base material 1, when heated to the expansion temperature range together with the thermal expansion layer 2, the base material 1 may become excessively softened, thinner, and melted to get holes or break, and welded to the device. Moreover, after heating is completed and the progress of expansion of the thermal expansion layer 2 is stopped due to natural cooling or the like, there is a possibility that the base material 1 may cause an unintended plastic deformation due to its own weight or the like.
Specifically, if the base material 1 is made from a crystalline resin, the base material 1 is at a temperature less than a fusing point and is easy to cause plastic deformation while keeping a sheet (film) shape at a heating temperature (maximum temperature) set within the expansion temperature range of the thermal expansion layer 2, preferably at a temperature at which the expansion coefficient of the microcapsules becomes maximum (maximum expansion temperature TEmax). That is, as described later in the manufacturing method, when heated to the same temperature, the base material 1 is bent by the load of expansion and deformation of the thermal expansion layer 2. Therefore, the material of the thermal expansion layer 2 is preferably prepared while setting the expansion temperature range according to the thermal properties of the thermoplastic resin constituting the base material 1.
The thermal expansion layer 2 has a larger amount of increase in volume due to expansion (expansion amount) as the thickness (initial thickness) to before molding is larger, so the load acting on the base material 1 due to deformation is higher to make the base material 1 easy to bend. On the other hand, when the initial thickness to of the thermal expansion layer 2 is large, the expansion amount becomes large accordingly. As a result, the sheet formed article 11 has the ridge lines greatly swelling and noticeably lifted. In addition, in the manufacturing process of the sheet formed article 11, heat is less likely to be transmitted to the base material 1. Specifically, the initial thickness to of the thermal expansion layer 2 is preferably 50 to 200 μm, and is further preferably designed according to the thickness of the base material 1 or the like.
The local expansion of the thermal expansion layer 2 is due to local heating to the thermal expansion layer 2. As described later in relation to a manufacturing method, the local heating is caused when the irradiation light is converted to heat and the heat is emitted by the photothermal conversion members 5 made from black ink attached to the surface of the thermal expansion layer-coated resin sheet 10.
(Release Layer)
The release layer 31 is provided as necessary to remove the photothermal conversion members 5 made from black ink and linearly printed on the surface of the thermal expansion layer-coated resin sheet 10 together with the ink reception layer 4 as the top layer in the process of manufacture of the sheet formed article 11. That is, the release layer 31 is releasable from the thermal expansion layer 2 just below. In addition, the release layer 31 does not contain an organic solvent or the like for dissolving the thermal expansion layer 2 at the time of formation, and is made of a material that does not require heating above the expansion start temperature TEs of the thermal expansion layer 2. The release layer 31 is merely required to fix the ink reception layer 4 on the surface until the light irradiation of the thermal expansion layer-coated resin sheet 10 is completed in the process of manufacturing the sheet formed article 11. For example, the release layer 31 may be of low elasticity and may be broken or peeled when the upper surface of the thermal expansion layer 2 (the interface with the release layer 31) is stretched and deformed after completion of the light irradiation. Moreover, the release layer 31 can be a heat-releasable adhesive of which adhesive strength is reduced by heating to a predetermined temperature or more. The predetermined temperature is lower than the expansion start temperature TEs of the thermal expansion layer 2 and is a heating temperature in a region to which the photothermal conversion members 5 are not attached due to light irradiation of the thermal expansion layer-coated resin sheet 10. For example, the release layer 31 can be a known easily releasable adhesive such as a vinyl chloride-vinyl acetate copolymer, which preferably has a thickness of about 1 μm to several μm. In addition, the release layer 31 may have a structure in which a resin film is laminated on the adhesive as described above. That is, the adhesive is applied to the surface of the thermal expansion layer 2 and the resin film is attached to the adhesive. With such a structure, the release layer 31 can efficiently remove the ink reception layer 4 in the process of manufacturing the sheet formed article 11. The resin film preferably has a thickness of about 10 to several tens of μm, and can be a known film commercially available for food packaging and the like.
(Ink Reception Layer)
Since the thermal expansion layer 2 is generally hydrophobic and it is difficult to attach the ink to the thermal expansion layer 2 before expansion, the ink reception layer 4 is provided on the outermost surface of the thermal expansion layer-coated resin sheet 10 so that the black ink constituting the photothermal conversion members 5 can attach to the ink reception layer 4. The ink reception layer 4 can be a layer for use in print sheets for a general ink jet printer. The ink reception layer 4 is made from porous silica or alumina (void type) that allows the ink to be absorbed in the voids, or a high water-absorption polymer (swelling type) or the like to absorb the ink by swelling. The ink reception layer 4 is formed to a thickness of about 10 to several tens μm depending on the material or the like.
[Method for Manufacturing the Sheet Formed Article]
(Manufacturing Devices)
Devices used for manufacturing the sheet formed article according to the present invention will be briefly described. In the manufacture of the thermal expansion layer-coated resin sheet 10 as a material of the sheet formed article 11, there are used coating devices that form the thermal expansion layer 2 before expansion, the release layer 31, and the ink reception layer 4 on the base material 1, and as necessary, a known cutting machine for cutting paper or the like (not illustrated) in order to process the thermal expansion layer-coated resin sheet 10 into a fixed size. In the manufacture of the sheet formed article 11, there are used a printing machine (not illustrated) that prints the photothermal conversion members 5 in black ink on the surface of the thermal expansion layer-coated resin sheet 10, a processing tool (not illustrated) that cuts the thermal expansion layer-coated resin sheet 10 into a developed shape of the sheet formed article 11, and a light irradiation device 7 (see
Each of the coating devices is a device for applying a coating material to a sheet-like member to form a coating film having a uniform thickness, which can be a known device of bar coater, roller, or spray type. In particular, the device for forming the thermal expansion layer 2 is particularly a bar coater type suitable for uniform thick coating.
The printing machine is a printing machine for printing the photothermal conversion members 5 in black ink, and can be selected from among known devices of offset or ink jet type corresponding to printing quality. In particular, the ink jet type suitable for small-volume production is preferred. In addition, the printing machine is compatible with the dimensions and thickness of the thermal expansion layer-coated resin sheet 10 as a printed matter. The printing machine is configured such that a printed matter is not heated exceeding the expansion start temperature TEs of the thermal expansion layer 2.
The processing tool is a tool for cutting the thermal expansion layer-coated resin sheet 10 into a developed shape of the sheet formed article 11 (see
The light irradiation device 7 is a device that irradiates the surface of the thermal expansion layer-coated resin sheet 10 with the photothermal conversion members 5 (printed surface) with light to heat the thermal expansion layer 2. Hereinafter, the light irradiation device will be briefly described with reference to
As illustrated in
The transport mechanism 8 transports the object to be processed in one horizontal direction at a constant speed so that the object to be processed is entirely moved (along length in the transport direction) through at least a region to be irradiated with light from the light irradiation unit 71, that is, by a distance with which the object to be processed is completely passed under the light irradiation unit 71. The transport mechanism 8 is, for example, a belt conveyor, and includes a belt 81, a head pulley (drive pulley) 82, a tail pulley 83, and a motor (not illustrated) for rotationally driving the head pulley 82. The belt 81 on which the object to be processed is to be placed is made of rubber or the like having a low thermal conductivity so as not to propagate heat in a planar direction in the thermal expansion layer-coated resin sheet 10 as the object to be processed.
The light irradiation device 7 can also vertically reverse the light irradiation unit 71 to irradiate the lower surface of the object to be processed (the thermal expansion layer-coated resin sheet 10) with light. In this case, since the light irradiation unit 71 is to be disposed under the transport mechanism 8 or under the upper belt 81, the belt 81 needs to be a translucent member that does not block the light from the light irradiation unit 71. The light transmitting belt is formed of, for example, a glass cloth impregnated with a highly heat resistant resin. The light transmitting belt can be a belt in a belt conveyor used for an appearance inspection of a product or the like.
The transport mechanism 8 is not limited to a belt conveyor, and may include, for example, a roller conveyor and a movable stage on which the object to be processed is to be placed (refer to a third embodiment described later). Alternatively, the transport mechanism 8 may be a known linear motion mechanism such as a rack and pinion gear system or a ball screw system, which is disposed avoiding the light irradiation area and connected to the edge of the stage. The transport mechanism 8 may be a linear motion mechanism that moves the light irradiation unit 71 in one direction instead of the object to be processed. The light irradiation device 7 may not include the transport mechanism 8 but the light irradiation unit 71 may include a plurality of light sources 7a to irradiate the object to be processed with light in a planar form so that the upper surface and the lower surface of the object to be processed can be entirely irradiated with light at the same time.
Alternatively, as illustrated in
The transport mechanism 8A transports the object to be processed in one horizontal direction at a constant speed to pass the light irradiation area. The transport mechanism 8A is a sheet loader applied to a transport mechanism in a printing machine or the like, and includes a main transport roller 84, transport rollers 85 and 85, and a motor (not illustrated) for rotationally driving these rollers. The main transport roller 84 is disposed on the upper side of the stage 74, and conveys the object to be processed while pressing the object to be processed from above onto the stage 74 and sliding the same. The main transport roller 84 is preferably disposed at the center or rear side of the light irradiation area as seen in the transport direction so as not to prevent the deformation of the object to be processed by the light irradiation. The transport rollers 85, 85 hold the object to be processed on both sides in a pair of upper and lower, and transport the workpiece from the top of the carry-in guide plate 75 onto the stage 74. The main transport roller 84 and the transport rollers 85, 85 are provided over the entire transport-width direction (total width) so as to transport the object to be processed in one direction regardless of the plan-view shape of the object to be processed, that is, the developed shape of the sheet formed article 11.
The transport mechanism 8B is provided as necessary to smoothly carry out the object having undergone the processing (light irradiation) from the light irradiation area, and is disposed below the stage 74 near the front side of the stage 74. The transport mechanism 8B is, for example, a belt conveyor similar to the transport mechanism 8 of the light irradiation device 7 (see
(Method for Manufacturing the Sheet Formed Article)
A method for manufacturing the sheet formed article according to the first embodiment will be described with reference to
In the thermal expansion layer formation step S11, as illustrated in
In the release layer formation step S12, the release layer 31 is formed on the thermal expansion layer 2 (see
In the cutting step S14, the base material 1 and the thermal expansion layer 2, the release layer 31, and the ink reception layer 4 thereon are cut to obtain the thermal expansion layer-coated resin sheet 10 (see
In the printing step S21, as illustrated in
Each of the photothermal conversion members 5 is a black pattern linearly formed on the surface of the thermal expansion layer-coated resin sheet 10. The sheet formed article 11 is formed by bending the base material 1 inside along the line. In the present embodiment, the photothermal conversion member 5 is formed on the surface of the base material 1 on the thermal expansion layer 2 side and thus corresponds to a mountain fold line. The photothermal conversion member 5 is a member that absorbs light of a specific wavelength range, for example, near-infrared light (wavelength 780 nm to 2.5 μm), converts the light into heat, and emits the heat. Specifically, the photothermal conversion member 5 is formed from a general black (K) printing ink containing carbon black. When irradiated with light, the photothermal conversion member 5 emits heat to heat the thermal expansion layer 2 and the base material 1 so that the thermal expansion layer 2 expands and the base material 1 can be plastically deformed. Further, in the printing step S21, the photothermal conversion member 5 may be printed not only as a mountain fold line but also as an outline (thick lines in
As the density of carbon black is higher, that is, the color is darker (more blackish), the heat generation temperature of the photothermal conversion member 5 when irradiated with light increases. Accordingly, the carbon black is adjusted to the density (black density) at which the thermal expansion layer 2 and the base material 1 are heated to an appropriate temperature in the subsequent light irradiation step S24. In addition, as the line width of the photothermal conversion member 5 (the length as seen in the lateral direction of the drawing) is larger, the photothermal conversion member 5 expands in a wider area in the thermal expansion layer 2 and the expansion amount (increase in the volume) becomes larger. This makes it possible to increase the load of the thermal expansion layer 2 on the base material 1 so that the base material 1 can be bent at larger angles. With a sufficiently large line width, the photothermal conversion member 5 can bend the base material 1 even if the black density is low to a certain extent. However, when the line width of the photothermal conversion member 5 is excessively large, the ridge line of the sheet formed article 11 has a low curvature and is rounded, and furthermore, the ridge line becomes a double line. On the contrary, when the line width of the photothermal conversion member 5 is too small, the expansion amount of the thermal expansion layer 2 is insufficient, and the heated region of the base material 1 is narrow, and the base material 1 cannot be bent. Furthermore, even if the black density is high, the absolute amount of carbon black is insufficient and the thermal expansion layer 2 does not expand. The photothermal conversion member 5 is designed to be high in black density and be large in line width so that, as the base material 1 is thicker, the photothermal conversion member 5 has a higher load acted on the base material 1 and the heat from the photothermal conversion member 5 propagates to the entire base material 1 in the thickness direction. In the subsequent light irradiation step S24, when the light output is high and the irradiation time is long, the expansion amount of the thermal expansion layer 2 increases. Therefore, the photothermal conversion member 5 is preferably set to have a line width as well as the black density depending on the thickness of the base material 1, the irradiation condition of light, and the like. Furthermore, the line width and the black density may be changed according to the bending angle to be determined. In addition, in the case of printing the outline described above, the outline is printed at a black density (gray) and with a line width such that the thermal expansion layer 2 is not heated exceeding the expansion start temperature TEs, or the inside of the outlie is cut and removed in the cutting step S23.
In the cutting step S23, the thermal expansion layer-coated resin sheet 10 on which the photothermal conversion member 5 is formed is cut out along the outline illustrated by a thick line in
In the light irradiation step S24, the surface (front surface) of the cut thermal expansion layer-coated resin sheet 10 on which the photothermal conversion members 5 are printed is irradiated with light by the light irradiation device 7 (7A). The thermal expansion layer-coated resin sheet 10 is transported by the transport mechanism 8 (8A) and the portions of the thermal expansion layer-coated resin sheet 10 on which the photothermal conversion members 5 are printed enter the light irradiation area, and the light is incident on and absorbed by the photothermal conversion members 5. Accordingly, the light is converted into heat and the photothermal conversion members 5 generate heat to heat the thermal expansion layer 2. Then, the heat further propagates from the surface of the thermal expansion layer 2 in the thickness direction to heat the base material 1. The portions of thermal expansion layer 2 having reached the expansion start temperature TEs foam and start to expand in four directions centering on the lines from immediately below the linear photothermal conversion members 5. As illustrated by void arrows in
In the present embodiment, in the case of using the light irradiation device 7 that irradiates light from the top, the thermal expansion layer-coated resin sheet 10 is processed with the surface facing upward, and the ridge lines are lifted as mountain folds as illustrated in
When the thermal expansion layer 2 has reached the expansion start temperature TEs, the base material 1 has preferably reached the thermal deformation temperature TD or more. When the base material 1 is at a temperature lower than the thermal deformation temperature TD, the thermal expansion layer 2 expands leaning to the front side. Accordingly, the expansion of the thermal expansion layer 2 to the line width direction becomes smaller. After that, even when the base material 1 reaches the thermal deformation temperature TD, the load on the base material 1 becomes lower and the bending angle becomes smaller. In the present embodiment, since the thermal expansion layer 2 is increased in temperature earlier than the base material 1 due to the heated photothermal conversion members 5. Thus, as described above, the expansion start temperature TEs of the thermal expansion layer 2 is preferably higher than the thermal deformation temperature TD of the base material 1. The heating temperature (maximum temperature) of the thermal expansion layer 2 is preferably around the maximum expansion temperature TEmax (approximately TEs+30 to 50° C.), specifically, (TEmax+5° C.) or less. Therefore, the photothermal conversion members 5 are designed to have a black density so as to generate heat at TEs or more and TD or more. Preferably, the photothermal conversion members 5 are designed to have a black density to generate heat near TEmax.
In addition, when the thermal expansion layer-coated resin sheet 10 is bent in the light irradiation region, the distance between the photothermal conversion member 5 on the surface of the thermal expansion layer-coated resin sheet 10 and the light source 7a changes, and thus the thermal expansion layer-coated resin sheet 10 may not be heated to the designed temperature. On the other hand, after the photothermal conversion member 5 is irradiated with light and generates heat, it takes some time until the heat propagates to the thermal expansion layer 2 and the base material 1 and the thermal expansion layer 2 and the base material 1 to start expansion and bending. Therefore, in the light irradiation step S24, the thermal expansion layer-coated resin sheet 10 preferably starts to bend after passing through the light irradiation area of the light irradiation device 7 (7A). The output of the light source 7a of the light irradiation device 7 and the transport speed are set such that the photothermal conversion member 5 is irradiated with light for a sufficient time to generate heat to a necessary temperature and that the thermal expansion layer-coated resin sheet 10 bends at the timing described above. In addition, the transport direction of the thermal expansion layer-coated resin sheet 10 is not particularly specified as far as the cut thermal expansion layer-coated resin sheet 10 (the developed shape of the sheet formed article 11) falls within the transport width of the light irradiation device 7 (7A). However, the transport-direction length of the photothermal conversion member 5 for forming a ridge line on one side of the sheet formed article 11 is preferably short. Therefore, the sheet formed article 11 is preferably transported in the right-left direction or the up-down direction in
Furthermore, in the case of using the light irradiation device 7, the thermal expansion layer-coated resin sheet 10 (the developed shape of the sheet formed article 11) preferably starts to bend after passing through the light irradiation area. While there is left an area yet to be irradiated with light by the light irradiation device 7, when the area having been already irradiated with light bends, the thermal expansion layer-coated resin sheet 10 may be lifted from the belt 81 as a predetermined transport path in the light irradiation area and may not be heated to the designed temperature, depending on the shape of the sheet formed article 11. On the other hand, when the light irradiation device 7A is used, the thermal expansion layer-coated resin sheet 10 is transported in a state of being entirely held at two places between the transport rollers 85 and 85, and between the main transport roller 84 and the stage 74 in the transport-width direction and being in contact with the stage 74. Accordingly, the distance between the light source 7a of the light irradiation unit 71 and the object to be processed is kept constant. Therefore, even if the entire thermal expansion layer-coated resin sheet 10 starts to bend before passing through the light irradiation area, the light is uniformly applied. Thus, the developed shape of the sheet formed article 11 may be large in dimensions.
In the ink removal step S25, the ink reception layer 4 is peeled off by the release layer 31 from the surface of the bent thermal expansion layer-coated resin sheet 10. Thereby, the photothermal conversion member 5 as a black line on a ridge line is removed, whereby the sheet formed article 11 illustrated in
The sheet formed article 11 is further assembled into a box as illustrated in
In the cutting step S23, the thermal expansion layer-coated resin sheet 10 may not be cut along all along the outlines, as long as the bending in the light irradiation step S24 is not impeded. In this case, after the light irradiation step S24, the bent thermal expansion layer-coated resin sheet 10 is cut along the remaining outlines using scissors or the like to cut off unnecessary portions.
When the light irradiation device 7A is used in the light irradiation step S24, the thermal expansion layer-coated resin sheet 10 is not held after its rear end has passed through the main transport roller 84, and light irradiation of the rear end and its vicinity will not be controlled. Therefore, for example, as for the sheet formed article 12 (see
The photothermal conversion members 5 can also be formed without using a printing machine. In the printing step S21, for example, mountain fold lines are formed on the surface of the thermal expansion layer-coated resin sheet 10 by hand-drawing with a writing instrument such as a black-ink felt pen, India ink and ink brush, and a pencil. The writing instrument is preferably easy to draw lines with a constant black density and a constant line width, and is also preferably less high in writing pressure since the thermal expansion layer 2 is soft. Specifically, the writing instrument is preferably a felt pen.
The sheet formed article 11 may not be subjected to the ink removal step S25 depending on the application such as trial manufacture, and the photothermal conversion members 5 may remain on the surface along the ridge lines. In this case, the thermal expansion layer-coated resin sheet 10 may not include the release layer 31, and therefore, the release layer formation step S12 is not performed.
The bent thermal expansion layer-coated resin sheet 10 may be turned into a sheet formed article 11A only made from the bent base material 1 as illustrated in
In order to make the thermal expansion layer 2 peelable from the base material 1, the thermal expansion layer-coated resin sheet 10B includes a release layer 31A between the thermal expansion layer 2 and the base material 1 as illustrated in
(Release Layer)
The release layer 31A is provided to remove the thermal expansion layer 2 expanded on the ridge line from the bent base material 1 (the sheet formed article 11A) in the manufacturing process of the sheet formed article 11A. The release layer 31A has at least temporary heat resistance to the heating temperature at which to expand the thermal expansion layer 2 in the manufacturing process of the sheet formed article 11A, has adhesive strength with which the release layer 31A is not peeled off when the thermal expansion layer 2 expands and the base material 1 bends, and forms a coating film that is flexible so as not to prevent the bending of the base material 1. The release layer 31A can be, for example, a thermosetting adhesive that can be cured at a temperature at which the base material 1 does not melt, or an ultraviolet curable adhesive. The release layer 31A preferably has a thickness of about 1 μm to several μm. Further, the release layer 31A may have a structure in which a flexible resin film is laminated on the adhesive. The resin film preferably has a thickness of about 1 to 20 μm so as not to inhibit heat transfer from the thermal expansion layer 2 to the base material 1, and can be a known film commercially available for food packaging and the like. Examples of the resin film include ethylene-vinyl alcohol copolymer (EVOH) resin film. Furthermore, the release layer 31A may be made from a resin film alone, which can be formed by thermocompression bonding (lamination) on the base material 1. The thermocompression bonding may be based on any heat sealing (heat welding) property of the base material 1 or the resin film constituting the release layer 31A.
(Method for Manufacturing the Sheet Formed Article)
According to the method for manufacturing the sheet formed article according to the present modification example, the thermal expansion layer-coated resin sheet manufacturing step S10 of manufacturing the thermal expansion layer-coated resin sheet 10B, the printing step S21, the cutting step S23, the light irradiation step S24, and the ink removal step S25 (thermal expansion layer removal step) are sequentially performed as illustrated in
After the thermal expansion layer 2 is formed on the release layer 31A made of a resin film, the release layer 31A and the base material 1 may be thermocompression-bonded at a temperature lower than the expansion start temperature TEs of the thermal expansion layer 2. Further, in the present modification example, the thermal expansion layer 2 and the base material 1 can be made separable from each other without providing the release layer 31A. Thus, the base material 1 is made from a resin that can be thermocompression-bonded at a temperature lower than the expansion start temperature TEs of the thermal expansion layer 2. Specifically, the thermal expansion layer 2 is formed on release paper or the like, the surface of the thermal expansion layer 2 and the base material 1 are thermocompression-bonded, and the release paper is peeled off to form the ink reception layer 4. Alternatively, the ink reception layer 4 may be formed on release paper or the like, and the thermal expansion layer 2 may be formed thereon.
The sheet formed article 11 can also be manufactured by printing a black line on the surface (back surface) of the thermal expansion layer-coated resin sheet on the base material 1 side and irradiating this surface with light. When the sheet formed article 11 is assembled into a box, lines are printed on the inner surface, the printed lines are on the inside and are difficult to recognize visually, so that the ink removal step S25 is not necessary. The sheet formed article 11 is manufactured from a thermal expansion layer-coated resin sheet 10C illustrated in
The thermal expansion layer-coated resin sheet 10C includes the ink reception layer 4 coating on the back surface of the base material 1 as illustrated in
(Method for Manufacturing the Sheet Formed Article)
A method for manufacturing the sheet formed article according to the present modification example will be described with reference to
In the printing step S21, as illustrated in
In the light irradiation step S24, the surface (back surface) of the cut thermal expansion layer-coated resin sheet 10C cut in the cutting step S23 and on which the photothermal conversion members 5A are printed is irradiated with light by the light irradiation device 7 (7A). Then, the photothermal conversion member 5A generates heat to heat the base material 1, and the heat further propagates through the base material 1 in the thickness direction to heat the thermal expansion layer 2. As a result, as illustrated in
In the present modification example, in the case of using the light irradiation device 7, the thermal expansion layer-coated resin sheet 10C is processed with the back surface (printed surface) oriented upward, so that the ridge lines form valley folds with ends lifted. On the other hand, in the case of using the light irradiation device 7A, the thermal expansion layer-coated resin sheet 10C is processed with the back surface oriented downward, and the ridge lines form mountain folds with ends lifted.
Since the thermal expansion layer-coated resin sheet 10C includes the ink reception layer 4 coating the front surface (on the thermal expansion layer 2), the photothermal conversion member 5 may be printed on the front surface as in the above embodiment. Manufacturing the sheet formed article 11 from the thermal expansion layer-coated resin sheet 10C makes it possible to attach black lines to any one of the outer surface and the inner surface, that is, not to attach the lines to the desired surface. Alternatively, the thermal expansion layer-coated resin sheet 10C may include the ink reception layer 4 covering only the back surface for printing on the back surface. Further, the thermal expansion layer-coated resin sheet 10C may include the release layer 31 (see
In the three-dimensional object according to the first embodiment, the two layers, that is, the thermal expansion layer and the base material are heated with the linear photothermal conversion member printed on one surface of the thermal expansion layer-coated resin sheet. Accordingly, there is the need to heat these two layers to their respective appropriate temperatures at appropriate timings only in the area on the lines (the photothermal conversion members) to bend the thermal expansion layer-coated resin sheet. Therefore, it is difficult to thicken the layers, especially the base material. Thus, a light-transmissive member to the base material so that the layers can be easily heated appropriately. Hereinafter, a three-dimensional object according to a second embodiment of the present invention will be described together with a method for manufacturing the same, with reference to
The sheet formed article (three-dimensional object) 11A according to the second embodiment of the present invention is a box illustrated in
The resin sheet 10A is a printed material on which the photothermal conversion member 5 is printed in black ink. As illustrated in
The base material 1A is broadly the same in configuration as the base material 1 in the first embodiment. However, the base material 1A is structured to sufficiently transmit light. When the base material 1A is to be colored, the amount of a pigment for the base material 1A is preferably suppressed as well as the thickness of the base material 1A. The base material 1A does not contain a black pigment. The release layer 31A is provided to remove the ink reception layer 4 and the thermal expansion layer 2 laminated thereon from the bent base material 1A (sheet formed article 11A) in the manufacturing process of the sheet formed article 11A. The release layer 31A is the same in configuration as the modification example of the first embodiment (see
(Method for Manufacturing the Sheet Formed Article)
In the method for manufacturing the sheet formed article according to the present embodiment, as illustrated in
In the thermal expansion layer formation step S11A, as illustrated in
In the release layer formation step S12A, the release layer 31A is formed on the base material 1A (see
In the printing step S21, as illustrated in
In the bonding step S22, as illustrated in
In the light irradiation step S24A, the cut laminated body of the resin sheet 10A and the thermal expansion film 20 is irradiated with light by the light irradiation device 7 (7A) applied to the surface of the resin sheet 10A side (the back surface of the base material 1A). When light passes through the base material 1A and enters the photothermal conversion members 5, the photothermal conversion members 5 generate heat to heat the upper and lower thermal expansion layer 2 and the base material 1A. Then, the laminated body is folded and bent from both sides of the lines (the photothermal conversion members 5) toward the base material 1A as illustrated in
In the present embodiment, in the case of using the light irradiation device 7, the laminated body is processed with the surface of the resin sheet 10A side (the back surface of the base material 1A) oriented upward, so that the ridge lines form valley folds with ends lifted. On the other hand, in the case of using the light irradiation device 7A, the laminated body is processed with the surface of the resin sheet 10A side oriented downward, and the ridge lines are lifted to form mountain folds.
In the thermal expansion layer removal step S25A, the thermal expansion film 20 bonded to the surface is peeled off from the bent resin sheet 10A. Both the ink reception layer 4 and the release layer 31A of the resin sheet 10A are removed by the adhesive layer 32 of the thermal expansion film 20, thereby to obtain the sheet formed article 11A made only of the bent base material 1A.
In the present embodiment, the thermal expansion film 20 may not include the adhesive layer 32 so that the thermal expansion film 20 and the resin sheet 10A are bonded together by the adhesive (the adhesive layer 32) in the bonding step S22.
In the present embodiment, the photothermal conversion members 5 may be printed on the thermal expansion film 20. For this purpose, in the thermal expansion layer formation step S11A, the thermal expansion layer 2 is applied to release paper or the like to form the ink reception layer 4 on the thermal expansion layer 2, and then the thermal expansion layer 2 is cut to dimensions corresponding to the printing machine, thereby to obtain the thermal expansion film 20. The photothermal conversion members 5 are formed on the ink reception layer 4 of the thermal expansion film 20. Then, the base material 1A is bonded to the printed surface of the thermal expansion film 20 (bonding step S22), and the release paper is peeled off to expose the thermal expansion layer 2 to the surface. At this time, the base material 1A and the thermal expansion film 20 may be bonded using the release layer 31A such as an adhesive, or may be bonded by thermocompression bonding at a temperature lower than the expansion start temperature TEs of the thermal expansion layer 2. Thereafter, as in the foregoing embodiments, the cutting step S23, the light irradiation step S24A, and the thermal expansion layer removal step S25A are sequentially performed.
In the present embodiment, the sheet formed article 11 (see
In the sheet formed article 11A according to the present embodiment, the thermal expansion layer 2, that is, the thermal expansion film 20 may not be provided on the entire surface in the manufacturing process, as long as the thermal expansion film 20 covers at least the photothermal conversion members 5. The thermal expansion film 20 preferably covers the photothermal conversion members 5 up to the thickness of the base material 1A or more on both outer sides of the lines as seen in the line width direction (and up to the initial thickness to of the thermal expansion layer 2). Moreover, the thermal expansion film 20 preferably has a certain degree of width or more to ensure the adhesiveness with the resin sheet 10A. Therefore, the thermal expansion film 20 is cut out in a strip shape in the cutting step S15. The strip-shaped thermal expansion film 20 is attached to the resin sheet 10A along the printed black lines (the photothermal conversion members 5) in the bonding step S22. Alternatively, the photothermal conversion members 5 may be printed on the thermal expansion film 20, and the thermal expansion film 20 be cut out in a strip shape such that the photothermal conversion members 5 become center lines, and the printed surface of the thermal expansion film 20 be attached to the portions of the base material 1A to be bent.
Each of the three-dimensional objects according to the first and second embodiments and their modification examples is bent with the surface of the base material coated with the thermal expansion layer oriented outward, and thus the three-dimensional object has a three-dimensional shape formed from mountain folds only (or valley folds only). Therefore, both the surfaces of a base material are covered with a thermal expansion layer so that a three-dimensional object has a mixture of mountain folds and valley folds. Hereinafter, a three-dimensional object according to a third embodiment of the present invention will be described with reference to
(Sheet Formed Article)
As illustrated in
The sheet formed article 13 according to the third embodiment of the present invention includes a base material 1 and thermal expansion layers 21 and 22 laminated on the both surfaces of the base material 1 as illustrated in
(Thermal Expansion Layer-Coated Resin Sheet)
A configuration of the thermal expansion layer-coated resin sheet 10D before the formation of the sheet formed article 13 will be described below with reference to
The configurations of the base material 1, the release layer 31, and the ink reception layer 4 are as described above in relation to the first embodiment. The first thermal expansion layer 21 and the second thermal expansion layer 22 (hereinafter, called collectively the thermal expansion layers 21 and 22 as appropriate) have the same configuration as the thermal expansion layer 2 of the first embodiment. The first thermal expansion layer 21 and the second thermal expansion layer 22 have the same material and initial thicknesses t1 and t2 (t1=t2). The thermal deformation temperature TD of the thermoplastic resin constituting the base material 1 is preferably equal to or lower than the expansion start temperature TEs, and more preferably lower than the expansion start temperature TEs. When the initial thicknesses t1 and t2 of the thermal expansion layers 21 and 22 are large, as described in relation to the first embodiment, the load acting on the base material 1 due to expansion becomes high in the manufacturing process of the sheet formed article 13. On the other hand, when the thermal expansion layer-coated resin sheet 10D bends, the thermal expansion layer 22 (21) on the inner side is folded tightly (with a high curvature). Due to its elasticity, the thermal expansion layer-coated resin sheet 10D is hard to bend, which inhibits plastic deformation of the base material 1. Specifically, the initial thicknesses t1 and t2 of the thermal expansion layers 21 and 22 are preferably 50 to 100 μm. Furthermore, the initial thicknesses t1 and t2 are preferably designed such that both the load due to the expansion of the outer thermal expansion layer 21 (22) and the interference by the thermal expansion layer 22 (21) with the inner non-expansion thickness t2 (t1) are appropriate.
(Manufacturing Devices) Devices used for manufacturing the sheet formed article according to the present embodiment will be briefly described. As in the manufacture of the thermal expansion layer-coated resin sheet 10 of the first embodiment, a coating device and a cutting machine are used in the manufacture of the thermal expansion layer-coated resin sheet 10D as a material of the sheet formed article 13 (not illustrated in the figures). In the manufacture of the sheet formed article 13, a printing machine to print the photothermal conversion members 51 and 52 in black ink on both sides of the thermal expansion layer-coated resin sheet 10D, and a processing tool to cut the thermal expansion layer-coated resin sheet 10D into the developed shape of the sheet formed article 13 (not illustrated) as described above in relation to the first embodiment. Furthermore, in the present embodiment, a light irradiation device 7B (see
As illustrated in
The transport mechanism 8C transports the stage 77 together with the object to be processed thereon at a constant speed in one horizontal direction, without blocking the light from the lower light irradiation unit 71. The transport mechanism 8C is a roller conveyor, for example, which includes a plurality of carrier rollers 86, 86, . . . , arranged in the transport direction and a motor and a transmission mechanism such as a belt or a chain (not illustrated) for rotationally driving the carrier rollers 86 at the same rotational speed (circumferential speed). The carrier rollers 86 are disposed avoiding the light irradiation area (immediately above the lower light irradiation unit 71). Alternatively, the transport mechanism 8C can be configured by a belt conveyor as the transport mechanism 8 of the light irradiation device 7. However, two belts are provided at both ends (both edges) in the transport-width direction so as not to block the light from the light irradiation units 71, and the stage 77 is bridged between the belts. Alternatively, as described above in relation to the first embodiment, the object to be processed can be placed directly on the transport mechanism 8 with the belt 81 (see
The light irradiation device 7B can also include a transport mechanism 8A configured by a sheet loader as in the light irradiation device 7A of the first embodiment (see
(Method for Manufacturing the Sheet Formed Article)
A method for manufacturing the sheet formed article according to the third embodiment will be described with reference to
In the thermal expansion layer formation step S11, the first thermal expansion layer 21 is formed on one surface (upper side) of the base material 1, and the second thermal expansion layer 22 is formed on the other surface (lower side) with their respective thicknesses t1 and t2 (t1=t2). The formation method of the thermal expansion layers 21 and 22 is the same as the thermal expansion layer formation step S11 of the first embodiment. Then, in the release layer formation step S12, the release layer 31 is formed on each of the thermal expansion layers 21 and 22. Then, in the ink reception layer formation step S13, the ink reception layer 4 is formed on each of the release layers 31 and 31 on both sides. For example, after sequential formation of the first thermal expansion layer 21, the release layer 31, and the ink reception layer 4 on one surface of the base material 1, the second thermal expansion layer 22, the release layer 31, and the ink reception layer 4 may be sequentially formed on the other surface of the base material 1. In the cutting step S14, as in the first embodiment, the base material 1 on which the thermal expansion layers 21 and 22 and others are formed is cut, thereby to obtain the thermal expansion layer-coated resin sheet 10D having a dimension corresponding to a printing machine used in the subsequent printing step S21 (see
In the printing step S21, as illustrated in
In the cutting step S23, the thermal expansion layer-coated resin sheet 10D on which the photothermal conversion members 51 and 52 are formed is cut out along the outline indicated by the thick line in
In the light irradiation step S24, the both surfaces of the cut thermal expansion layer-coated resin sheet 10D are irradiated with light by the light irradiation device 7B. The photothermal conversion member 51 generates heat due to the light from above to heat the first thermal expansion layer 21, and the heat further propagates from the surface of the first thermal expansion layer 21 in the thickness direction (downward) to heat the base material 1. In addition, the photothermal conversion member 52 generates heat due to light from below to heat the second thermal expansion layer 22, and the heat further propagates from the surface of the second thermal expansion layer 22 in the thickness direction (upward) to heat the base material 1. As a result, as illustrated in
Here, immediately below the photothermal conversion member 51, the heat from the photothermal conversion member 51 sequentially propagates through the first thermal expansion layer 21 and the base material 1, and further propagates to the second thermal expansion layer 22. The heating temperature (maximum temperature) of the second thermal expansion layer 22 immediately below the photothermal conversion member 51 is lower than that of the first thermal expansion layer 21 such that, even when expanding due to the heating, the amount of the expansion of the second thermal expansion layer 22 is reduced to be smaller than that of the first thermal expansion layer 21. Ideally, it is preferable that the second thermal expansion layer 22 does not expand, that is, does not reach the expansion start temperature TEs or higher of the thermal expansion layers 21 and 22. On the other hand, the expansion amount of the first thermal expansion layer 21 is preferably larger. Therefore, as described above in relation to the first embodiment, the heating temperature of the first thermal expansion layer 21 is preferably near a maximum expansion temperature TEmax of the thermal expansion layers 21, 22. Similarly, immediately above the photothermal conversion member 52, the expansion amount of the first thermal expansion layer 21 is preferably smaller than that of the second thermal expansion layer 22, and the expansion amount of the second thermal expansion layer 22 is preferably larger. From these facts, as with the photothermal conversion member 5 of the first embodiment, t is preferable that the photothermal conversion members 51 and 52 be designed to have a black density so as to generate heat at a temperature near the maximum expansion temperature TEmax. In the light irradiation step S24, after the photothermal conversion members 51 and 52 and the first thermal expansion layer 21 or the second thermal expansion layer 22 nearest the photothermal conversion members 51 and 52 reach the maximum temperature, it is preferred to stop the light irradiation immediately to naturally cool these components. Most preferably, the second thermal expansion layer 22 or the first thermal expansion layer 21 tardily increasing in temperature via the base material 1 is cooled without reaching the expansion start temperature TEs. Therefore, the heating speed (the temperature rising speed of the photothermal conversion members 51 and 52) is preferably high, and the output and the conveyance speed of the light source 7a of the light irradiation device 7B are set such that this temperature transition takes place. In addition, materials and the like of the base material 1 and the thermal expansion layers 21 and 22 are selected such that the base material 1 is heated to the thermal deformation temperature TD or more under such conditions.
In the ink removal step S25, as in the first embodiment, the ink reception layer 4 is peeled off with the release layer 31 from each of the both surfaces of the bent thermal expansion layer-coated resin sheet 10D, thereby to obtain the sheet formed article 13 illustrated in
In the sheet formed article 13, the photothermal conversion members 51 and 52 may remain on the both surfaces or one surface along the ridge lines depending on the application such as trial manufacture. In this case, the thermal expansion layer-coated resin sheet 10D may not have the release layer 31 on both surfaces or on one surface.
The sheet formed article 13 may be formed from only the bent base material 1 by peeling and removing the ink reception layer 4 together with the thermal expansion layers 21 and 22 therebelow in the ink removal step S25, as with the sheet formed article 11A according to the modification example of the first embodiment (see
The sheet formed article 13 can be manufactured by applying light to each of the surfaces of the thermal expansion layer-coated resin sheet 10D using the light irradiation device 7A (see
In the printing step S21, as illustrated in
The heating from the black lines and the gray lines printed on both surfaces using the light irradiation device 7B as in the modification example is also applicable to the manufacture of the sheet formed articles 11 and 11A according to the first embodiment and the modification example. That is, as in the thermal expansion layer-coated resin sheet 10C (see
The three-dimensional object according to the third embodiment and the modification example is manufactured by coating both surfaces of the base material with a thermal expansion layer to form a shape with a mixture of mountain folds and valley folds and applying light to both surfaces. However, the three-dimensional object can also be manufactured by applying light to only one surface. Hereinafter, a three-dimensional object manufacturing method according to a fourth embodiment of the present invention will be described. The same elements as those in the above embodiments (see
In the three-dimensional object manufacturing method according to the present embodiment, the sheet formed article (three-dimensional object) 13 obtained has the shape and the structure illustrated in
(Method for Manufacturing the Sheet Formed Article)
A method for manufacturing the sheet formed article according to the present embodiment will be described with reference to
In the thermal expansion layer formation step S11, as in the third embodiment, the first thermal expansion layer 21 is formed on one surface (upper side) of the base material 1, and the second thermal expansion layer 22 is formed on the other surface (lower side) with their respective thicknesses t1 and t2 (t1=t2). Then, in the release layer formation step S12, the release layer 31 is formed on the first thermal expansion layers 21. Then, in the ink reception layer formation step S13, the ink reception layer 4 is formed on the release layer 31. In the cutting step S14, as in the first embodiment, the base material 1 on which the thermal expansion layers 21 and 22 and others are formed is cut, thereby to obtain the thermal expansion layer-coated resin sheet 10E having a dimension corresponding to a printing machine used in the subsequent printing step S21 (see
In the printing step S21, as illustrated in
In the cutting step S23, as in the third embodiment, the thermal expansion layer-coated resin sheet 10E on which the photothermal conversion members 51A and 52A are formed is cut out along the outline indicated by the thick line in
In the light irradiation step S24, the surface (one surface) of the cut thermal expansion layer-coated resin sheet 10E on which the photothermal conversion members 51A and 52A are printed is irradiated with light by the light irradiation device 7 (7A). Then, the photothermal conversion members 51A and 52A generate heat at temperatures corresponding to the respective black densities, and the heat sequentially propagates through the first thermal expansion layer 21, the base material 1, and the second thermal expansion layer 22. As illustrated in
Further, immediately below the photothermal conversion member 52A, the base material 1 reaches the thermal deformation temperature TD or more, and the second thermal expansion layer 22 reaches the expansion start temperature TEs or more and expands. On the other hand, the first thermal expansion layer 21 nearest the photothermal conversion member 52A is heated to a higher temperature and exceeds the maximum expansion temperature TEmax. In general, when the microcapsules are heated to a high temperature exceeding the maximum expansion temperature TEmax, the contained volatile solvent diffuses through the shell at a high speed, so the expansion rate decreases, and the microcapsules shrink when they have already expanded. Therefore, immediately below the photothermal conversion member 52A, the first thermal expansion layer 21 has an expansion coefficient that is less than the maximum expansion coefficient, and further is lower than the expansion coefficient of the second thermal expansion layer 22. As a result, the second thermal expansion layer 22 has a larger expansion amount than the first thermal expansion layer 21 and has a high load acting on the base material 1. Accordingly, as illustrated in
As described above, immediately below the photothermal conversion member 52A, the nearest first thermal expansion layer 21 preferably reaches a temperature (about TEs+50 to 80° C.) that is higher than the maximum expansion temperatures TEmax of the thermal expansion layers 21 and 22 at which the expansion coefficient is sufficiently lowered. For this end, the photothermal conversion member 52A is preferably designed to have a black density so as to generate heat at the high temperature described above exceeding the maximum expansion temperature TEmax. The second thermal expansion layer 22 reaches near the maximum expansion temperature TEmax to increase the expansion amount, but has no further temperature increase. Specifically, the second thermal expansion layer 22 is preferably at a temperature of (TEmax+5° C.) or less, more preferably at a temperature lower than TEmax. Further, since the base material 1 is heated to a higher temperature immediately below the photothermal conversion member 52A than immediately below the photothermal conversion member 51A, the base material 1 is capable of plastic deformation with a lower load. Thus, even when the first thermal expansion layer 21 expands to some extent and the difference in expansion amount between the first thermal expansion layer 21 and the second thermal expansion layer 22 becomes small, the base material 1 can be bent immediately below the photothermal conversion member 52A on a par with immediately below the photothermal conversion member 51A.
As in the third embodiment, the heating rates of the photothermal conversion members 51A and 52A (the temperature increase rates of the photothermal conversion members 51A and 52A) are preferably high, and the photothermal conversion members 51A and 52A are preferably cooled at once after reaching the maximum temperatures such that the first thermal expansion layer 21 and the second thermal expansion layer 22 immediately below the photothermal conversion members 51A and 52A show the temperature gradients described above.
In the ink removal step S25, as in the first embodiment, the ink reception layer 4 is peeled off with the release layer 31 from the surface of the bent thermal expansion layer-coated resin sheet 10E, thereby to obtain the sheet formed article 13 illustrated in
As in the third embodiment, the photothermal conversion members 51A and 52A may remain along the ridge lines on the sheet formed article 13 depending on the application such as trial production. In this case, the thermal expansion layer-coated resin sheet 10E may not include the release layer 31. The sheet formed article 13 may be formed from only the bent base material 1 and the second thermal expansion layer 22 covering one surface of the base material 1 by peeling off the ink reception layer 4 together with the first thermal expansion layer 21 in the ink removal step S25. Alternatively, the sheet formed article 13 may be formed from only the bent base material 1 (not illustrated) by further peeling off the second thermal expansion layer 22, as with the sheet formed article 11A (see
In the present embodiment, the first thermal expansion layer 21 and the second thermal expansion layer 22 are differentiated in expansion amount with different expansion coefficients. To make the base material 1 easier to bend by increasing the difference in expansion amount, as illustrated in
The method for manufacturing the sheet formed article 13A from the thermal expansion layer-coated resin sheet 10F is the same as that of the fourth embodiment (see
In the thermal expansion layer-coated resin sheet 10F, the first thermal expansion layer 21A and the second thermal expansion layer 22A need to be different only in expansion amount (absolute amount) at the same expansion rate. The first thermal expansion layer 21A and the second thermal expansion layer 22A may be adjusted such that the second thermal expansion layer 22A is larger in expansion amount than the first thermal expansion layer 21A at their respective expansion rates by not only setting the different initial thicknesses t1 and t2 but also changing the compound ratio of microcapsules or the like, for example.
In the method for manufacturing a sheet formed article according to the fourth embodiment, in the thermal expansion layers 21 and 22 sandwiching the base material 1 from both sides, the desired side is expanded at a relatively high expansion rate to freely produce mountain folds and valley folds using a temperature gradient caused by different distances from the photothermal conversion members 51A and 52A on surface. Alternatively, the expansion rates of the thermal expansion layers 21 and 22 can be controlled in the same manner by structuring the thermal expansion layers 21 and 22 to be different in expansion temperature range. Hereinafter, a method for manufacturing a sheet formed article according to the modification example of the fourth embodiment will be described.
In the present modification example, the sheet formed article 13 is manufactured from a thermal expansion layer-coated resin sheet 10G illustrated in
The configurations of the base material 1, the release layer 31, and the ink reception layer 4 are as described above in relation to the first and third embodiments. The first thermal expansion layer 21B and the second thermal expansion layer 22B (hereinafter, called collectively the thermal expansion layers 21B and 22B as appropriate) have the same configuration as the thermal expansion layers 21 and 22 of the third and fourth embodiments, and have the same initial thicknesses t1 and t2 (t1=t2). However, the first thermal expansion layer 21B and the second thermal expansion layer 22B are blended so that expansion start temperatures T1Es and T2Es are different, and the expansion start temperature T2Es of the second thermal expansion layer 22B is higher than the expansion start temperature T1Es of the first thermal expansion layer 21B (T1Es<T2Es). A maximum expansion temperature T1Emax of the first thermal expansion layer 21B is preferably lower than a maximum expansion temperature T2Emax of the second thermal expansion layer 22B (T1Emax<T2Emax), and is further preferably lower than the expansion start temperature T2Es of the second thermal expansion layer 22B (T1Emax<T2Es). Moreover, the thermal deformation temperature TD of the thermoplastic resin constituting the base material 1 is lower than the expansion start temperature T2Es of the second thermal expansion layer 22B (TD<T2Es). The thermal properties of the base material 1 and the thermal expansion layers 21B and 22B in the present modification example will be described below in detail in relation to the manufacturing method.
(Method for Manufacturing the Sheet Formed Article)
A method for manufacturing the sheet formed article according to the present modification example will be described with reference to
In the thermal expansion layer formation step S11, the first thermal expansion layer 21B is formed on one surface (upper side) of the base material 1, and the second thermal expansion layer 22B is formed on the other surface (lower side) with their respective thicknesses t1 and t2 (t1=t2). The formation method of the thermal expansion layers 21B and 22B is the same as the thermal expansion layer formation step S11 of the first embodiment. In the present modification example, since the first thermal expansion layer 21B and the second thermal expansion layer 22B are different in material, a slurry is prepared for each of them. Then, in the release layer formation step S12, the release layer 31 is formed on the second thermal expansion layers 22B. Then, in the ink reception layer formation step S13, the ink reception layer 4 is formed on the release layer 31. In the cutting step S14, as in the first embodiment, the base material 1 on which the thermal expansion layers 21B and 22B and others are formed is cut, thereby to obtain the thermal expansion layer-coated resin sheet 10G having a dimension corresponding to a printing machine used in the subsequent printing step S21 (see
In the printing step S21, as illustrated in
In the cutting step S23, as in the embodiment described above, the thermal expansion layer-coated resin sheet 10G on which the photothermal conversion members 51B and 52B are formed is cut out along the outline indicated by the thick line in
In the light irradiation step S24, the cut thermal expansion layer-coated resin sheet 10G is irradiated with light by the light irradiation device 7 (7A) applied to the surface on the side (other side) on which the photothermal conversion members 51B and 52B are printed. Then, the photothermal conversion members 51B and 52B generate heat at temperatures corresponding to the respective black densities, and the heat sequentially propagates through the second thermal expansion layer 22B, the base material 1, and the first thermal expansion layer 21B. Further, immediately below the photothermal conversion member 51B, the base material 1 reaches the thermal deformation temperature TD or more, and the first thermal expansion layer 21B reaches the expansion start temperature T1Es or more and expands. As a result, as illustrated in
Further, immediately below the photothermal conversion member 52B, the second thermal expansion layer 22B reaches the expansion start temperature T2Es or more and expands, and the base material 1 reaches the thermal deformation temperature TD or more. On the other hand, the first thermal expansion layer 21B reaches a high temperature exceeding the maximum expansion temperature TE1max and has a lower expansion coefficient than that of the second thermal expansion layer 22B. Therefore, as illustrated in
Immediately below the photothermal conversion member 52B, the base material 1 preferably reaches the thermal deformation temperature TD in order to prevent plastic deformation of the base material 1 due to expansion of the first thermal expansion layer 21B, and the first thermal expansion layer 21B preferably reaches a temperature (maximum temperature) at which the expansion coefficient sufficiently decreases as in the fourth embodiment before the first thermal expansion layer 21B reaches the expansion start temperature T1Es and expands to plastically deform the base material 1. Alternatively, the second thermal expansion layer 22B preferably reaches the expansion start temperature T2Es and starts expansion. Therefore, the heating rate (the temperature increasing rate of the photothermal conversion members 51B and 52B) is preferably high. In the same manner as in the fourth embodiment, the base material 1 is heated to a higher temperature immediately below the photothermal conversion member 52B than immediately below the photothermal conversion member 51B, and is plastically deformable with a lower load. Further, the present modification example is effective even in a case where it is difficult to generate a sufficient temperature gradient between the thermal expansion layers 21B and 22B, such as when the base material 1 is thin.
In the ink removal step S25, as in the foregoing embodiment, the ink reception layer 4 is peeled off with the release layer 31 from the surface of the bent thermal expansion layer-coated resin sheet 10G, thereby to obtain the sheet formed article 13 illustrated in
In the present modification example, as in the third and fourth embodiments, the photothermal conversion members 51B and 52B may remain along the ridge lines on the sheet formed article 13 depending on the application such as trial production. In this case, the thermal expansion layer-coated resin sheet 10G may not include the release layer 31. Further, as described in relation to the above embodiment, when the ink reception layer 4 is removed in the ink removal step S25, the ink reception layer 4 may be peeled off together with the second thermal expansion layer 22B, and further the first thermal expansion layer 21B may also be peeled off.
Also in the present modification example, as in the fourth embodiment, in order to make the base material 1 easy to bend by increasing the difference in expansion amount, the initial thicknesses t1 and t2 of the thermal expansion layers 21B and 22B may be made different as in the thermal expansion layer-coated resin sheet 10F (see
The three-dimensional object according to the present invention is manufactured by bending with light irradiation in the manufacturing process. Accordingly, when the dimension of the developed shape of the three-dimensional object before irradiation is large, a region earlier irradiated with light is bent in a state in which there remains a region yet to be irradiated with light by the light irradiation device. In this case, as described above in relation to the modification example of the first embodiment, it is possible to appropriately apply light to the three-dimensional object by conveying in a state of being held in the sheet loader. However, the conveyance may be difficult depending on the shape of the three-dimensional object. Also, the three-dimensional object is ideally in non-contact with the device when irradiated with light. Therefore, the light irradiation device is configured such that the position of the three-dimensional object is fixed in a limited manner while being in non-contact with the device in the light irradiation region. Hereinafter, a three-dimensional object manufacturing method according to a fifth embodiment of the present invention will be described with reference to
(Light Irradiation Device)
In the present embodiment, a light irradiation device 7C illustrated in
The transport mechanism 8D transports the object to be processed in one horizontal direction at a constant speed to pass the light irradiation area. The transport mechanism 8D includes total four sets of belt conveyors that are arranged on both edges to hold and transport an object to be processed of a fixed size near both ends (both edges) as seen in a transport-width direction, and are provided above and below the object to be processed such that the object to be processed is held at least in the light irradiation region. Therefore, the transport mechanism 8D includes four belts 81A, four head pulleys (drive pulleys) 82, and four tail pulleys 83, and further includes idle pulleys 87 on the upper two sets of belt conveyors and motors (not illustrated) to rotationally drive the four head pulleys 82. In addition, the transport mechanism 8D may further include a carry-in guide plate 75 and a transport roller 85 of the light irradiation device 7A behind the transport mechanism 8D.
The cutting mechanism 9 is a slitter that cuts the object to be processed continuously along the transport direction at a predetermined position inside the transport mechanism 8D as seen in the transport-width direction. The cutting mechanism 9 includes an upper blade 91 and a lower blade 92 in front of the light irradiation region near the both edges to sandwich the object to be processed from above and below. The positions of the blades 91 and 92 as seen in the transport direction are in front of the light irradiation area and behind the position where the object to be processed (the thermal expansion layer-coated resin sheet 10) starts to bend. The blades 91 and 92 are preferably adjustable in the position in the transport-width direction or in the transport direction.
According to the light irradiation device 7C, the object to be processed is stably irradiated with light in the light irradiation region without deviating from the transport path. In addition, the object to be processed is not in contact with parts of the light irradiation device 7C and others so that the heat propagation state is uniform and the expansion of the thermal expansion layer is not impeded. On the other hand, the object to be processed are cut at both edges held in the transport mechanism 8D by the cutting mechanism 9 at the time of passage through the light irradiation area, so that the bending and deformation of the object to be processed are not impeded. In addition, the light irradiation device 7C may be configured such that the light irradiation unit 71, the cooler 72, and the protection plate 73 are vertically reversed so that the lower surface of the object to be processed is irradiated with light. Alternatively, the light irradiation device 7C may include the two light irradiation units 71, the two coolers 72, and the two protection plates 73 to apply light to both sides of the object to be processed at the same time.
For light irradiation by the light irradiation device 7C, the thermal expansion layer-coated resin sheet 10 is formed such that, in the cutting step S23, a frame 10f is left at a peripheral edge and a portion of the outline is not cut but is coupled to the frame 10f by tie bars 10b as illustrated in
In the light irradiation step S24, the thermal expansion layer-coated resin sheet 10 cut as described above is irradiated with light by the light irradiation device 7C, and the tie bars 10b are cut by the cutting mechanism 9 when having passed through the light irradiation region so that the thermal expansion layer-coated resin sheet 10 can start to bend along the photothermal conversion members 5. Then, after the light irradiation step S24, the remaining tie bars 10b are cut off by scissors or the like along the outline from the bent thermal expansion layer-coated resin sheet 10.
In the above embodiment, the light irradiation device includes a cutting mechanism to mechanically cut off the both edges of the object to be processed. However, the object to be processed is mainly made of a thermoplastic resin and thus the both edges of the object to be processed can be cut off without using the cutting mechanism. Hereinafter, a three-dimensional object manufacturing method according to a modification example of the fifth embodiment of the present invention will be described with reference to
In the present modification example, the light irradiation device 7C (see
As in the above embodiment, the thermal expansion layer-coated resin sheet 10 is formed such that, in the cutting step S23, a frame 10f is left at a peripheral edge and a portion of the outline is not cut but is coupled to the frame 10f by tie bars 10b as illustrated in
In the light irradiation step S24, the thermal expansion layer-coated resin sheet 10 cut as described above is irradiated with light by the light irradiation device 7C, and the portions of the thermal expansion layer-coated resin sheet 10 having passed through the light irradiation area start to bend along the photothermal conversion members 5 and melt immediately below the lines 5d. Accordingly, the tie bars 10b are cut under the load of bending. After the light irradiation step S24, the remaining tie bars 10b are cut off by scissors or the like along the outline from the bent thermal expansion layer-coated resin sheet 10.
Each of the three-dimensional objects according to the first to fourth embodiments of the present invention has a three-dimensional shape formed by bending a flat surface, or a three-dimensional shape formed by curving a developable surface. However, since the thermoplastic resin constituting the base material is thermally deformable, a sheet formed article (not illustrated) can be manufactured with a surface similar to a three-dimensional curved surface with a skeleton of a linear area in which the photothermal conversion members are formed. The thermal expansion layer-coated resin sheet 10 is bent at each of the photothermal conversion members 5 in a narrow region between the photothermal conversion members 5 and 5 and thus is largely curved as a whole and gently curved in a wide region. Accordingly, the thermal expansion layer-coated resin sheet 10 can be changed into an arbitrary face shape by a pattern of the photothermal conversion members 5, or can be adjusted in bending angle by the black density and line width of the photothermal conversion members 5. In particular, since the base material 1 is easy to heat to the thermal deformation temperature TD or more and deform immediately below and in the vicinity of the photothermal conversion members 5, forming narrowly the space between the photothermal conversion members 5 and 5 makes it possible to deform the base material 1 into smoother curved surface.
As described above, according to the present invention, it is possible to obtain a desired three-dimensional shape in which a resin sheet is bent or curved without using a mold or the like.
The present invention is not limited to the above embodiment, and can be modified without departing from the spirit of the present invention.
Hereinafter, as examples of the present invention, samples simulating a sheet formed article according to the modification example of the first embodiment (see
Straight lines with the black density and the line width illustrated in Table 1 and Table 2 were printed using an ink jet printer in black ink (photothermal conversion members) on the back surface (ink reception layer) of the produced thermal expansion layer-coated resin sheet, and then the thermal expansion layer-coated resin sheet was cut into a rectangle of 15 mm×30 mm. In each of the cut thermal expansion layer-coated resin sheets, the printed straight line is oriented in the short-side direction at a position of 10 mm from one end as seen in the longitudinal direction. The thermal expansion layer-coated resin sheet was placed with the back surface (printing surface) oriented upward, and while about ⅔ of the thermal expansion layer-coated resin sheet on the one end side as seen in the longitudinal direction was protruded, the remaining portion (about ⅓ as seen in the longitudinal direction) was stuck to an upper surface of a square block with a double-sided tape. Then, the thermal expansion layer-coated resin sheet was fixed from above by a cellophane tape. The fixed thermal expansion layer-coated resin sheet was held horizontally including the portion protruding from the square block, and the lower surface (thermal expansion layer) of the protruding portion was made noncontact. Finally, the thermal expansion layer-coated resin sheet was irradiated with light by a near-infrared heater from above 20 mm. At this time, the near-infrared heater was horizontally moved at the movement speeds illustrated in Table 1 and Table 2 so as to cross the printed straight line from the side of the thermal expansion layer-coated resin sheet fixed to the square block (in the longitudinal direction of the thermal expansion layer-coated resin sheet). The movement speeds of 650, 700 and 750 pps (pulses/second) correspond to linear speeds of 27.1, 29.2 and 31.2 mm/s, respectively. The near-infrared heater used a 1000 W straight-tube type halogen lamp as a light source, and was a parabola (diffusion) type equipped with a reflector of about 45 mm in width, and was attached to a linear-motion mechanism so as to be movable in the width direction. Tables 1 and 2 show the visually measured bending angles of the thermal expansion layer-coated resin sheets (samples) irradiated with light.
When irradiated with light, each of the thermal expansion layer-coated resin sheets was bent with the printed straight lines as concave ridges and the downward surface (thermal expansion layer) oriented outward, and was deformed such that one longitudinal end not fixed to the square block stood up. As illustrated in Tables 1 and 2, the higher the linear black density and the longer the line width, the larger the bending angle became, 180° at maximum, that is, the thermal expansion layer-coated resin sheet was completely folded. However, in samples printed in a light straight line with black density below a certain level or a thin straight line with a maximum black density (100%) and a line width smaller than a specific value or lower, each of the thermal expansion layer-coated resin sheets had the bending angle of 0°, that is, did not bend and remained flat. In addition, in samples at slow movement speeds of the halogen lamp, that is, samples with long light irradiation times, each of the thermal expansion layer-coated resin sheets had a large bending angle and was bent even along a light straight line or a thin straight line. In addition, the thermal expansion layer-coated resin sheets provided with the release layer had smaller bending angles than those without the release layer.
As described above, when the black density and the line width of the photothermal conversion member are set to specific values or more, the thermal expansion layer is heated to a temperature higher than the expansion start temperature and expands in the area where the photothermal conversion members are printed. As a result, the thermal expansion layer-coated resin sheet can be bent. Furthermore, by printing with a high black density and a large line width, the thermal expansion layer expands greatly, and the base material is heated and softened, and as a result, the bending angle can be increased. In addition, when the light irradiation time is made longer, the temperatures of the photothermal conversion member and the thermal expansion layer increase. Thus, even when the photothermal conversion member is low in black density or small in line width, the thermal expansion layer can be expanded and the thermal expansion layer-coated resin sheet can be bent, thereby further increasing the bending angle. In addition, the thermal expansion layer-coated resin sheet is more difficult to bend as the thickness of the base material or the total thickness including the thickness of the release layer is larger. Therefore, the black density and the line width, and the light irradiation time are preferably set according to the thickness and the required bending angle of the base material. In particular, as in the present example, the thermal expansion layer and the thermal expansion layer-coated resin sheet with the surface opposite to the thermal expansion layer as the printing surface are separated by the base material or the like. Accordingly, it is considered that, as the base material or the like is thicker, it takes more time that heat propagates from the photothermal conversion member to the thermal expansion layer, and the thermal expansion layer-coated resin sheet is unlikely to be bent when the light irradiation time is short.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2018-171968 | Sep 2018 | JP | national |
| 2019-114981 | Jun 2019 | JP | national |
