JP2020040290A - Molded article and method for producing molded article - Google Patents

Abstract

To provide a molded article having a flatter surface.SOLUTION: A plate-shaped base material 20 includes a thermoplastic resin fiber 22 and a thermally expandable capsule 23. The thermally expandable capsule 23 has a flat shape in which a length of the base material 20 in a plate thickness direction is smaller than a length in a direction along a surface of the base material 20. A surface-side capsule 23A, which is the thermally expandable capsule 23 exposed on a surface of the base material 20, is flatter than an inner-side capsule 23B, which is the thermally expandable capsule 23 disposed inside the base material 20. By making the surface-side capsule 23A exposed on a surface of the base material 20 flatter, irregularities on the surface of the base material 20 can be made smaller, and the surface of the base material 20 is made more flat.SELECTED DRAWING: Figure 6

Description

  The technology disclosed in the present specification relates to a molded article and a method for manufacturing the molded article.

  BACKGROUND ART Conventionally, a molded article including a thermally expandable capsule has been known (Patent Document 1 below). Patent Literature 1 discloses a fiber in which a thermally expandable capsule is dispersed in a fiber. The heat-expandable capsule expands when heated during manufacturing. Thereby, the weight of the molded body can be reduced.

JP-A-2006-141740

  As described above, in the molded article provided with the heat-expandable capsule, there is a possibility that the heat-expandable capsule is exposed on the surface of the molded article. As a result, irregularities due to the thermally expandable capsule are generated on the surface of the molded body, and the flatness of the molded body surface is reduced. When the flatness of the surface of the molded body is reduced, for example, when the skin material is attached to the surface of the molded body, irregularities are generated on the skin material, and the design property is reduced.

  The technology disclosed in the present specification has been completed based on the above circumstances, and an object thereof is to provide a molded body having a flatter surface.

  As a means for solving the above problems, the molded body disclosed in the present specification is a plate-shaped molded body containing a thermoplastic resin and a thermally expandable capsule, wherein the thermally expandable capsule is The length along the plate thickness direction of the body has a flat shape smaller than the length along the surface of the molded body, and the thermally expandable capsule exposed on the surface of the molded body is It is characterized in that it is flatter than the heat-expandable capsule disposed inside the molded body. By making the heat-expandable capsule exposed on the surface of the molded body flatter, irregularities on the surface of the molded body can be made smaller, and the surface of the molded body can be made more flat. .

  Further, as a means for solving the above problems, a method for manufacturing a molded body disclosed in the present specification is a method for manufacturing a molded body formed by molding a plate material containing a thermoplastic resin and a thermally expandable capsule. A first heating step of heating the plate so as not to expand the thermally expandable capsule disposed inside the plate while expanding the thermally expandable capsule exposed on the surface of the plate; A first pressing step that is performed after the first heating step and press-molds the plate material to make the heat-expandable capsule exposed on the surface of the plate material into a flat shape; and A second heating step of expanding the thermally expandable capsule disposed inside the plate material by heating the plate material, and a second heating step performed after the second heating step to press-mold the plate material To do The heat-expandable capsule disposed on the inner side of the plate is formed into a flat shape, and the heat-expandable capsule exposed on the surface of the plate is disposed on the inner side of the plate. A second pressing step of making the shape flatter than the capsule.

  By the first pressing step, the thermally expandable capsule exposed on the surface of the plate is crushed. Thereby, the thermally expandable capsule has a flat shape, and the density near the surface of the plate material can be further increased. For this reason, the situation where the temperature of the surface of the plate is lowered in the process of shifting from the second heating step to the second pressing step can be suppressed, and the press forming can be performed in the second pressing step in a state where the vicinity of the surface of the sheet is more softened. it can. As a result, in the second pressing step, the heat-expandable capsules exposed on the surface of the plate can be made flatter than the heat-expandable capsules arranged inside the plate, and Since the unevenness due to the exposed thermally expandable capsule can be reduced, the surface of the plate material can be made flatter.

  Further, in the first pressing step, the plate material may be press-formed so that the thickness of the plate material is smaller than in the second pressing step. By making the thickness of the plate material smaller than the thickness of the compact in the first pressing step (the thickness of the plate material after the second pressing step), the thermally expandable capsule exposed on the surface of the plate material is more reliably crushed. And the surface of the plate material can be made flatter. In the above manufacturing method, even if the thickness of the plate material is smaller than the thickness of the molded body (the target thickness as a product) in the first pressing step, the inner side of the plate material is not heated in the second heating step. Since the thickness of the plate material can be increased by expanding the thermally expandable capsule, the thickness of the plate material can be set to a target thickness as a product in the second pressing step.

  According to the present invention, a molded article having a flatter surface can be provided.

Front view showing a door trim including a lower board according to an embodiment of the present invention. The figure which shows the structure of a base material schematically (state before performing 1st heating process) Diagram showing first heating step Diagram showing first press process The figure which shows a 2nd heating process Diagram showing the second pressing process The figure which shows the comparative example of the heating process which heats a board | plate material. The figure which shows the comparative example of the press process which press-molds a board material

  One embodiment of the present invention will be described with reference to FIGS. In the present embodiment, a substrate 20 (see FIG. 2) constituting the lower board 13 is exemplified as a molded body. The lower board 13 constitutes the door trim 10 for a vehicle. As shown in FIG. 1, the door trim 10 mainly includes a trim board 11. The trim board 11 is divided into an upper board 12 forming an upper part of the door trim 10, a lower board 13 forming a lower part of the door trim 10, and a middle board 14 located between the upper board 12 and the lower board 13. I have. In the door trim 10, an ornament 15 is provided between the upper board 12 and the middle board 14. Further, a door pocket 16 is provided on the lower board 13.

  As shown in FIG. 6, the lower board 13 includes a base material 20 (lower board main body) and a skin material 40 attached to a surface of the base material 20 (a surface on the vehicle interior side). The base material 20 includes vegetable fibers 21, thermoplastic resin fibers 22 (thermoplastic resin), and thermally expandable capsules 23. Examples of the vegetable fibers 21 include bast vegetable fibers such as kenaf, and wood fibers obtained by unraveling wood. Examples of the thermoplastic resin fibers 22 include polyolefin resins (polypropylene, polyethylene, etc.), polyester resins (aliphatic polyester resins such as polylactic acid and polycaprolactone, and aromatic polyester resins such as polyethylene terephthalate). . In the present embodiment, kenaf is exemplified as the vegetable fiber 21 and polypropylene is exemplified as the thermoplastic resin fiber 22, but each material of the vegetable fiber 21 and the thermoplastic resin fiber 22 is not limited thereto. It can be changed as appropriate. The skin material 40 constitutes the design surface of the lower board 13 and is a flexible sheet-like member, for example, a resin sheet, woven fabric, non-woven fabric, leather, or the like. Further, as the skin material 40, a material in which a cushion layer or the like is lined with a sheet-like member may be used.

  The base material 20 is formed by pressing a plate material 19 (see FIG. 2) into a shape of the lower board 13 by press molding. After the plate material 19 is impregnated with the thermally expandable capsule 23 in a fiber mat formed by blending the vegetable fiber 21 and the thermoplastic resin fiber 22, the fiber mat is heated at a temperature at which the thermoplastic resin fiber 22 melts. It is formed into a plate by pressing. Such a plate member 19 may be called a preboard. As a method for hot-pressing the fiber mat, a method such as a double belt press method or a die press method can be used.

  In the plate member 19, the thermoplastic resin fibers 22 function as a binder for binding the vegetable fibers 21. The thermally expandable capsule 23 has a shell wall (capsule) made of a thermoplastic resin and a foaming agent contained in the shell wall. The heat-expandable capsule 23 is heated in two heating steps (a first heating step and a second heating step) to be described later, so that the internal foaming agent foams (expands), and the softened shell wall expands the foaming agent. It is configured to be expanded and expanded in volume. By including such a heat-expandable capsule 23, the base material 20 having a low basis weight and high rigidity can be formed. The thermally expandable capsule 23 has a spherical shape both before and during expansion.

  Examples of the shell wall constituting the heat-expandable capsule 23 include acrylonitrile-based resins, acrylic esters, methacrylic esters, aromatic vinyl compounds, aliphatic vinyl compounds, vinyl chloride, vinylidene chloride, and crosslinkable monomers. But not limited to this. In addition, examples of the foaming agent contained in the thermally expandable capsule include hydrocarbons. Specifically, propane, n-butane, isobutane, n-pentane, isopentane, n-hexane, isohexane, aliphatic hydrocarbons such as n-octane, cyclopentane, cyclohexane, alicyclic hydrocarbons such as methylcyclohexane, Examples thereof include halogenated hydrocarbons such as chlorohydrocarbons such as methyl chloride and ethyl chloride, and fluorinated hydrocarbons such as 1,1,1,2-tetrafluoroethane and 1,1-difluoroethane. It is not limited to.

  Next, a method for manufacturing the base material 20 (and, consequently, the lower board 13) will be described. The method of manufacturing the base material 20 includes a first heating step of heating the plate material 19, a first pressing step performed after the first heating step, and a second heating step performed after the first pressing step to heat the plate material 19. The method includes a heating step and a second pressing step performed after the second heating step.

(First heating step)
At a stage before the first heating step, as shown in FIG. 2, all the thermally expandable capsules 23 included in the plate member 19 are in a non-expanded state and have a spherical shape. In the first heating step, as shown in FIG. 3, the plate 19 is heated from both front and back sides by a pair of heating devices 30. As the heating device 30, for example, a hot air supply device capable of blowing hot air to the plate member 19 can be exemplified. However, the heating device 30 is not limited thereto, and an infrared heater or the like may be used as the heating device 30. .

  In the first heating step, the plate member 19 is heated so as not to expand the thermally expandable capsule 23 arranged inside the plate member 19 while expanding the thermally expandable capsule 23 exposed on the surface of the plate member 19. Specifically, the thermal expansion capsule 23 exposed on the surface of the plate member 19 may be expanded before the temperature at which the thermally expandable capsule 23 on the inner side of the plate member 19 expands. Heating is performed at a higher temperature and in a shorter time than in the heating step (heating step for expanding the heat-expandable capsule 23 on the inner side). The plate 19 heated in the first heating step is in a softened state. The diameter of the thermally expandable capsule 23 before expansion is, for example, 40 μm, and the diameter of the thermally expandable capsule 23 after expansion is, for example, 180 μm, but is not limited thereto.

  In the following description, the thermally expandable capsule 23 exposed on the surface of the plate 19 is referred to as a front capsule 23A, and the thermally expandable capsule 23 disposed inside the plate 19 is referred to as an inner capsule 23B. . That is, the front-side capsule 23A is the thermally expandable capsule 23 expanded in the first heating step, and the inner-side capsule 23B is disposed on the inner side of the plate member 19 with respect to the front-side capsule 23A. This is a thermally expandable capsule 23 that has not expanded. In the first heating step, the thickness A2 of the plate 19 after heating (see FIG. 3) is larger than the thickness A1 of the plate 19 before heating (see FIG. 2) by the expansion of the surface-side capsule 23A. growing. For example, the thickness A1 is set to 3 mm, and the thickness A2 is set to 5 to 6 mm, but is not limited thereto.

(First press process)
In the first pressing step, as shown in FIG. 4, the plate material 19 in a heated state is press-formed by a pair of press dies 31. As a result, the thickness A3 of the plate 19 becomes smaller than the thickness A2 of the plate 19 before the first pressing step (see FIG. 3), and the spherical surface-side capsule 23A is crushed in the thickness direction of the plate 19. This results in a flat shape (spheroid). Here, the term “flat” refers to a direction in which the length of the thermally expandable capsule 23 along the thickness direction of the plate material 19 (vertical direction in FIG. 4) is along the surface of the plate material 19 (the direction orthogonal to the thickness direction of the plate material 19). (For example, the horizontal direction in FIG. 4). In the process in which the expanded thermally expandable capsule 23 is crushed, the gas inside the thermally expandable capsule 23 is released to the outside. Further, in the first pressing step, the thickness (plate thickness) of the plate member 19 (base member 20) is made smaller than in a second pressing step (step of forming the plate member 19 into the base member 20) described later. The plate 19 is pressed. For example, the thickness A3 of the plate 19 immediately after the first pressing step is set to 2.5 mm, and the thickness A5 (see FIG. 6) of the plate 19 (base material 20) immediately after the second pressing step is set to 3.5 mm. However, the present invention is not limited to this.

(Second heating step)
In the second heating step, as shown in FIG. 5, the plate 19 is heated from both front and back sides by a pair of heating devices 30. In the second heating step, the inner capsule 23B (the thermally expandable capsule 23 not expanded in the first heating step) is expanded. The plate 19 heated in the second heating step is in a softened state. In the above-described first heating step, the plate 19 is heated with, for example, 240 ° C. hot air for 120 seconds, and in the second heating step, for example, the plate 19 is heated with 210 ° C. hot air for 150 seconds. The time is an example when the expansion start temperature of the thermally expandable capsule 23 is 205 ° C., and is not limited to this heating temperature and heating time.

  In the second heating step, the thickness A4 of the plate 19 after heating (see FIG. 5) is larger than the thickness A3 of the plate 19 before heating (see FIG. 4) by expanding the inner capsule 23B. growing. For example, the thickness A3 is set to 2.5 mm and the thickness A4 is set to 8 to 9 mm, but is not limited thereto. Note that the surface-side capsule 23A has already expanded in the first heating step and has been crushed in the first pressing step, so that the gas inside has escaped and does not expand in the second heating step.

(2nd pressing process)
In the second pressing step, as shown in FIG. 6, the plate material 19 is press-formed by the pair of press dies 42 and 43 to form the base material 20, and the base material 20 and the skin material 40 are integrally formed. I do. A plurality of suction holes 45 for evacuating the skin material 40 are formed in the press die 42 for molding the surface of the lower board 13 on the vehicle interior side. Thus, the skin material 40 is sucked through the suction hole 45 by a pump (not shown), and the skin material 40 can be formed in close contact with the forming surface 42A of the press die 42.

  In the second pressing step, the skin material 40 in a softened state by being heated in advance is brought into close contact with the molding surface 42A of the press die 42 so as to be shaped into a shape following the molding surface 42A. Then, the heated plate member 19 is press-formed together with the skin member 40 to form the lower board 13. In the process of pressing the plate member 19 and the skin member 40, the thickness A5 of the base member 20 (plate member 19) becomes smaller than the thickness A4 of the plate member 19 (see FIG. 5) before the second pressing step, and the inner side is reduced. When the capsule 23B is crushed in the thickness direction of the plate 19, the capsule 23B has a flat shape. In addition, the surface-side capsule 23A, which has already been flattened in the first pressing step, becomes flatter by being crushed in the thickness direction of the plate member 19. For this reason, in the thickness direction of the substrate 20, the length of the front-side capsule 23A is smaller than the length of the inner-side capsule 23B. That is, the front-side capsule 23A has a flatter shape than the inner-side capsule 23B.

  When the base material 20 and the skin material 40 are pressurized by the pair of press dies 42 and 43, the thermoplastic resin (a part of the thermoplastic resin fiber 22) near the surface of the base material 20 is converted to the skin material 40. Penetrates into the interior of Thereafter, the base material 20 and the skin material 40 are joined to each other by cooling and solidifying the thermoplastic resin that has penetrated into the skin material 40. Thereby, the lower board 13 is completed by integrally forming the base material 20 and the skin material 40.

  In the lower board 13, as shown in FIG. 6, the length L1 of the thermally expandable capsule 23 (including the surface-side capsule 23 </ b> A and the inner-side capsule 23 </ b> B) in the thickness direction of the base material 20 corresponds to the surface of the lower board 13. It has a flat shape smaller than the length L2 along the direction. In addition, since the thermally expandable capsule 23 in the lower board 13 has a substantially oblate sphere, the length L2 is a length corresponding to the diameter of the thermally expandable capsule 23 in a plan view viewed from any one side in the plate thickness direction. is there. The surface-side capsule 23A is smaller than the inner-side capsule 23B in the length along the thickness direction of the base material 20. That is, the front-side capsule 23A (the thermally-expandable capsule exposed on the surface of the molded body) is flatter than the inner-side capsule 23B (the thermally-expandable capsule disposed inside the molded body).

  Next, effects of the present embodiment will be described. In the present embodiment, as compared to the inner capsule 23B, the surface-side capsule 23A has a flatter shape, so that the unevenness of the surface of the base material 20 can be reduced, and the surface of the base material 20 can be further reduced. It can be flat. This makes it possible to more reliably suppress the occurrence of irregularities on the surface of the skin material 40 when the skin material 40 is attached to the surface of the base material 20.

  In the present embodiment, the thermally expandable capsule 23 exposed on the surface of the plate 19 is crushed by the first pressing step. Accordingly, the heat-expandable capsule 23 has a flat shape, and the density near the surface of the plate 19 can be made higher than when the heat-expandable capsule 23 is not crushed after expansion. For this reason, a situation where the temperature of the surface of the plate 19 is reduced in the process of shifting from the second heating step to the second pressing step can be suppressed, and the press working is performed in a state where the vicinity of the surface of the plate 19 is softened in the second pressing step. be able to. As a result, in the second pressing step, the heat-expandable capsule 23 (surface-side capsule 23A) exposed on the surface of the base material 20 (plate material 19) is placed on the heat-expandable capsule 23 (inside the base material 20). As compared with the side capsule 23B), it is possible to have a flatter shape and to reduce unevenness due to the thermally expandable capsule 23 exposed on the surface of the base material 20, so that the surface of the base material 20 is flatter. Things.

  If all the heat-expandable capsules 23 are expanded in the heating step as shown in FIG. 7 and then pressed by a pair of press dies 52 and 53 as shown in FIG. The density near the surface of the plate 19 is low because the 23 is expanded, and the temperature of the surface of the plate 19 decreases in the process of shifting from the heating step to the pressing step. The thermally expandable capsule 23 cannot be sufficiently crushed. As a result, the thermally expandable capsule 23 having a shape closer to a sphere (the thermally expandable capsule 23 in a low flatness state) is exposed on the surface of the substrate 20, and the flatness of the surface of the substrate 20 is reduced. Will drop. In the present embodiment, such a situation can be suppressed.

  Further, in the first pressing step, the plate material 19 is pressed such that the thickness of the plate material 19 (base material 20) is smaller than in the second pressing step. By making the thickness of the plate member 19 smaller than the thickness of the base member 20 (thickness of the plate member 19 after the second press step) in the first pressing step, the surface-side capsule 23A of the plate member 19 is more reliably crushed. The surface of the plate member 19 can be made flatter. In the present embodiment, even if the thickness of the plate material 19 is smaller than the thickness of the base material 20 (thickness targeted as a product) in the first pressing step, the internal pressure is not increased in the second heating step. Since the side capsule 23B can be expanded to increase the plate thickness of the plate member 19, the thickness of the plate member 19 can be set to a target thickness as a product in the second pressing step.

<Other embodiments>
The present invention is not limited to the embodiments described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention.
(1) In the above-described embodiment, the base material 20 constituting the lower board 13 is illustrated as a molded body, but the present invention is not limited to this. The molded body may be a component of a door trim other than the lower board 13 or an interior material for a vehicle other than the door trim (instrument panel, luggage trim, package tray, etc.). Further, the molded body may be an interior material (vehicle interior material) mounted on a vehicle other than the vehicle, or may be a member other than the interior material.
(2) In the above-described embodiment, an example in which the base material 20 and the skin material 40 are integrally formed in the second pressing step is exemplified, but the present invention is not limited to this. After the plate member 19 is formed into the base member 20 by press molding, the skin member 40 may be attached to the surface of the base member 20 in the next step. However, since the lower board 13 often has a complicated three-dimensional shape, and the skin material 40 needs to be formed into a complicated shape, it is more preferable to form the skin material 40 by evacuation.

19: plate material, 20: base material (molded body), 22: thermoplastic resin fiber (thermoplastic resin), 23: thermally expandable capsule, 23A: surface side capsule (thermally expanded capsule exposed on the surface of the molded body) ), 23B ... Inner side capsule (thermally expandable capsule disposed inside the molded body)

Claims (3)

A plate-like molded body containing a thermoplastic resin and a thermally expandable capsule,
The heat-expandable capsule has a flat shape in which the length of the molded body along the thickness direction is smaller than the length of the molded body along the surface thereof,
A molded article in which the thermally expandable capsule exposed on the surface of the molded article is flatter than the thermally expandable capsule disposed inside the molded article. A method for producing a molded body formed by molding a plate material containing a thermoplastic resin and a thermally expandable capsule,
A first heating step of heating the plate so as not to expand the thermally expandable capsule arranged inside the plate, while expanding the thermally expandable capsule exposed on the surface of the plate;
A first pressing step which is performed after the first heating step and press-molds the plate material to make the thermally expandable capsule exposed on the surface of the plate material flat.
A second heating step performed after the first pressing step and heating the plate to expand the thermally expandable capsule disposed on the inner side of the plate;
The heat treatment is performed after the second heating step, and by pressing the plate material, the heat-expandable capsule disposed inside the plate material is formed into a flat shape, and the surface exposed to the surface of the plate material is formed. A second pressing step of forming the heat-expandable capsule into a flatter shape than the heat-expandable capsule disposed inside the plate material.   3. The method according to claim 2, wherein in the first pressing step, the plate material is press-formed so that a plate thickness of the plate material is smaller than in the second pressing step. 4.

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