Manufacturing method of integrally molded body

Abstract

To manufacture an integrally molded body in which occurrence of wrinkles is suppressed.SOLUTION: There is provided a method of manufacturing an integrally molded body, comprising: a step in which a melted thermoplastic resin (A) is extruded downward from a die 10 and a parison 2a in a softened state is placed between split dies 11a and 11b; a step in which a molded portion of a sheet material 3 is held by a plurality of sheet material holding pins 12 installed to protrude from a cavity surface of the split die 11a in a mold clamping direction X, the sheet material 3 is moved together with the split mold 11a in the mold clamping direction X, and the molded portion of the sheet material 3 is brought into contact with the parison 2a, and the molded portion of the sheet material 3 and the parison 2a are adhered; a step in which the mold clamping is completed while adjusting a protrusion height of the sheet material holding pin 12 to be low; a step in which the parison 2a adhered with the sheet material 3 is blow molded together with the sheet material 3; and a step in which the integrally molded body 1 in which the sheet material 3 is adhered to a part of a blow molded body 2 obtained by blow molding is taken out from the die.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing an integrally molded body. [Background technology]

[0002] Conventionally, when blow molding by extruding a parison between split molds, it is known to place a sheet material such as a nonwoven fabric between the split mold and the parison, and integrally mold the sheet material and the blow-molded body (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 63-92431 Summary of the Invention [Problem to be solved by the invention]

[0004] In Patent Document 1, a nonwoven fabric is clamped at its upper edge and placed hanging down between a split mold and a parison, and air is blown into the parison to pre-blow the parison while the split mold is closed, bringing the parison and the nonwoven fabric into contact with each other and then bringing them into contact with a part of the cavity surface of the split mold. After the split mold is closed, compressed air is blown into the parison and simultaneously the air between the cavity surface of the split mold and the parison is forcibly discharged to the outside, so that the parison and the nonwoven fabric are sandwiched and thermocompressed around the entire mating surface of the mold, and while in contact, the parison and the nonwoven fabric slide along the cavity surface and expand, and are integrally molded into a three-dimensional shape corresponding to the uneven shape of the cavity surface.

[0005] The present inventors have conducted extensive research focusing on this background technology and have found that the method disclosed in Patent Document 1 may cause wrinkles to form in the nonwoven fabric used as the sheet material, and that wrinkles are particularly likely to form in the nonwoven fabric used as the sheet material in the recessed portion of the product where the convex shape of the cavity surface is transferred and molded.

[0006] Therefore, in view of the above background technology, the inventors conducted further intensive research to provide a method for manufacturing an integrally molded body of a sheet material and a blow-molded body in which the occurrence of wrinkles is suppressed, and as a result, they have completed the present invention. [Means for solving the problem]

[0007] The method for producing an integrally molded body according to the present invention is a method for producing an integrally molded body in which a sheet material is bonded to a portion of a blow-molded body made of a thermoplastic resin (A), and includes the steps of: extruding a melt of the thermoplastic resin (A) downward through a die to place a softened parison between split molds; holding the molded portion of the sheet material with a plurality of sheet material holding pins that protrude from the cavity surface of the split mold in the mold clamping direction; moving the sheet material together with the split mold in the mold clamping direction to abut the molded portion of the sheet material against the parison and bond the molded portion of the sheet material to the parison; completing mold clamping while adjusting the protruding height of the sheet material holding pins to a low level; blow-molding the parison to which the sheet material is bonded together with the sheet material; and removing the integrally molded body obtained by blow molding, in which the sheet material is bonded to a portion of the blow-molded body, from the mold. [Effects of the Invention]

[0008] According to the present invention, it is possible to manufacture an integrally molded body in which the occurrence of wrinkles is suppressed. [Brief explanation of the drawings]

[0009] [Figure 1] 3A to 3C are explanatory views schematically illustrating steps of a method for manufacturing an integrally molded body according to an embodiment of the present invention. [Figure 2] 3A to 3C are explanatory views schematically illustrating steps of a method for manufacturing an integrally molded body according to an embodiment of the present invention. [Figure 3] 3A to 3C are explanatory views schematically illustrating steps of a method for manufacturing an integrally molded body according to an embodiment of the present invention. [Figure 4] 3A to 3C are explanatory views schematically illustrating steps of a method for manufacturing an integrally molded body according to an embodiment of the present invention. [Figure 5] 3A to 3C are explanatory views schematically illustrating steps of a method for manufacturing an integrally molded body according to an embodiment of the present invention. [Figure 6] 3A to 3C are explanatory views schematically illustrating steps of a method for manufacturing an integrally molded body according to an embodiment of the present invention. [Figure 7] 3A to 3C are explanatory views schematically illustrating steps of a method for manufacturing an integrally molded body according to an embodiment of the present invention. [Figure 8] 3A to 3C are explanatory views schematically illustrating steps of a method for manufacturing an integrally molded body according to an embodiment of the present invention. [Figure 9] 10 is an explanatory view showing an example of a holding means for holding a molded portion of a sheet material by a sheet material holding pin in a manufacturing method of an integrally molded product according to an embodiment of the present invention. FIG. [Figure 10] 10 is an explanatory view showing another example of a holding means for holding a molded portion of a sheet material by a sheet material holding pin in a manufacturing method of an integrally molded product according to an embodiment of the present invention. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

[0011] Figures 1 to 8 are explanatory diagrams that schematically show a series of steps in this embodiment, and in this embodiment, the object to be produced is an integrally molded body 1 in which a sheet material 3 is bonded to a part of a blow molded body 2 made of a thermoplastic resin (A).

[0012] Examples of the thermoplastic resin (A) used in the blow-molded body 2 include polyolefin-based resins such as low-density polyethylene (LDPE), high-density polyethylene (HDPE), linear low-density polyethylene (LLDPE), propylene homopolymer (h-PP), propylene-ethylene random copolymer (r-PP), and propylene-ethylene block copolymer (b-PP); polystyrene-based resins such as polystyrene (styrene homopolymer: GPPS), high-impact polystyrene (HIPS), styrene-methyl methacrylate copolymer (MS), acrylonitrile-styrene copolymer (AS), polystyrene-modified polyphenylene ether (modified PPE), and acrylonitrile-styrene-butadiene copolymer (ABS); polyester-based resins such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polylactic acid (PLA); and polycarbonate-based resins such as bisphenol-type polycarbonate (PC), or mixtures thereof.

[0013] Among these resins, polyolefin resins are particularly preferred, and polyethylene resins and polypropylene resins are even more preferred. In the present invention, the polyolefin resin may contain a thermoplastic resin other than the polyolefin resin and / or an elastomer, provided that the intended effects of the present invention are not impaired. The content of the thermoplastic resin other than the polyolefin resin and / or the elastomer is preferably 30 parts by weight or less, more preferably 15 parts by weight or less, per 100 parts by weight of the polyolefin resin.

[0014] Furthermore, when the polyolefin resin is a polypropylene resin, the melting point is preferably 120 to 170°C. From the viewpoints of moldability and heat resistance, the melting point is preferably 130 to 170°C, and more preferably 140 to 165°C. The melting point can be measured in accordance with JIS K7121 (2010). Furthermore, when the polyolefin resin is a polyethylene resin, the melting point is preferably 110 to 140°C. From the viewpoints of moldability and heat resistance, the melting point is preferably 115 to 130°C. The melting point can be measured in accordance with JIS K7121 (2010). Furthermore, from the viewpoint of blow moldability, polyolefin resins having a melt flow rate (MFR) of 0.1 to 10 g / 10 min are preferred. From the viewpoint of blow moldability, the MFR is preferably 0.3 to 1.0 g / 10 min, and more preferably 0.3 to 0.7 g / 10 min. The melt flow rate (MFR) of polyolefin resins is measured based on test condition M (temperature 230°C, load 21.18N) of JIS K7210 (1999) for polypropylene resins, and test condition D (temperature 190°C, load 21.18N) of JIS K7210 (1999) for polyethylene resins.

[0015] Various additives can be added to the thermoplastic resin (A). Examples of additives include conductivity-imparting agents, antioxidants, heat stabilizers, weathering agents, ultraviolet inhibitors, flame retardants, inorganic fillers, antibacterial agents, electromagnetic wave shielding agents, gas barrier agents, and antistatic agents. These additives are added in an amount that achieves their intended purpose and effect, and the amount added is generally 10 parts by weight or less, preferably 5 parts by weight or less, and more preferably 3 parts by weight or less, per 100 parts by weight of the thermoplastic resin (A).

[0016] On the other hand, the sheet material 3 can be made of a thermoplastic resin (B). The thermoplastic resin (B) used for the sheet material 3 can be any of the resins listed as the thermoplastic resin (A) described above. Resins appropriately selected in consideration of adhesion to the parison 2a and the blow-molded article 2 can be used alone or in combination. Depending on the resin used for the thermoplastic resin (A), the thermoplastic resin (B) preferably contains a resin highly compatible with the thermoplastic resin (A), and more preferably contains the same or identical resin as the thermoplastic resin (A). For example, when a polyolefin-based resin is used as the thermoplastic resin (A), the thermoplastic resin (B) preferably contains 5 wt% or more of the same or identical polyolefin-based resin, more preferably 10 to 100 wt%, and even more preferably 30 to 100 wt%. The above content represents the content of the polyolefin-based resin relative to the weight of the thermoplastic resin (B) constituting the entire sheet material 3. For example, when the sheet material 3 has a single-layer structure, this indicates that the thermoplastic resin (B) constituting the sheet material 3 contains a specific amount of polyolefin-based resin. Furthermore, when the sheet material 3 has a multilayer structure, it has a multilayer structure consisting of a layer made of a polyolefin-based resin or a thermoplastic resin containing a polyolefin-based resin on the adhesive surface side of the sheet material 3 and a layer made of another thermoplastic resin, and this indicates that a specific amount of polyolefin-based resin is contained in relation to the total weight of the sheet material 3 made of thermoplastic resin (B). More specifically, when a polypropylene-based resin is used as the thermoplastic resin (A), it is preferable to use a polypropylene-based resin as the same type of resin as the thermoplastic resin (B). The melting point of the thermoplastic resin (B) is preferably 120 to 170°C, more preferably 125 to 160°C, from the viewpoint of adhesion to the blow molded article 2. Furthermore, from the viewpoint of adhesion between the sheet material and the blow molded article 2 and maintaining the thickness of the sheet material, the difference in melting point between the thermoplastic resin (A) and the thermoplastic resin (B) is preferably 10 to 30°C, more preferably 10 to 20°C. The method for measuring the melting point is the same as the method for measuring the thermoplastic resin (A).

[0017] Furthermore, the specific form of the sheet material 3 is not particularly limited, but examples of the sheet material 3 include woven fabric, nonwoven fabric, knitted fabric, and resin sheet. Among these, it is preferable that the sheet material 3 has sufficient breathability to prevent air bubbles from remaining at the adhesive interface between the molded portion of the sheet material 3 (or the portion to be molded) and the parison 2a when blow molding the integrally molded body 1 as described below. More specifically, the sheet material 3 is preferably a woven fabric or a nonwoven fabric. When the sheet material 3 is a nonwoven fabric, nonwoven fabrics exemplified in JIS L0222 can be used. The method for producing the nonwoven fabric is not limited, but among them, a nonwoven fabric obtained by a needle punching method is preferable from the viewpoint of integral molding. When the sheet material 3 is formed of a nonwoven fabric, the basis weight of the nonwoven fabric is 150 to 300 g / m 2 From the viewpoint of improving the appearance when the integrally molded body 1 is formed, a material having a thickness of 170 to 250 g / m 2 The thickness of the nonwoven fabric is preferably 1.5 to 3.0 mm, from the viewpoint of improving the feel of the surface of the integrally molded body 1 against the skin.

[0018] In this embodiment, to manufacture the integrally molded body 1, first, a melt of thermoplastic resin (A) is extruded vertically downward into a cylindrical shape from the annular discharge port of the die 10 between a pair of split molds 11a, 11b that are waiting in an open state, and a softened parison 2a is placed between the split molds 11a, 11b. At this time, it is preferable to pinch the tip of the parison 2a extruded from the die 10 in the extrusion direction to fuse it, and then blow air into the parison 2a from a blowing port (not shown) provided on the inner periphery of the annular discharge port of the die 10, thereby adjusting the shape of the parison 2a so that the circumferential length of the parison 2a is roughly constant along the vertical direction (see FIG. 1).

[0019] In the illustrated example, a plurality of sheet material holding pins 12 are installed in one of the split molds 11a, protruding from the cavity surface in the mold clamping direction X. The sheet material 3 is preferably arranged so that the plane of the molded portion thereof intersects, preferably orthogonal to, the mold clamping direction X. In other words, the sheet material 3 is preferably held at the tip of the sheet material holding pins 12 in a planar state, preferably parallel to, the extrusion direction of the parison 2a. When the sheet material holding pins 12 hold the molded portion of the sheet material 3, the holding means is not particularly limited as long as it can hold the sheet material 3 so that it can be released during mold release. For example, as shown in FIG. 9 , the sheet material 3 can be held by inserting a locking portion 12a provided at the tip of the sheet material holding pin 12 into a holding hole 3a drilled in the sheet material 3. When a woven or nonwoven fabric is used as the sheet material 3, the sheet material 3 can also be held by a hook-and-loop fastener 12b provided at the expanded diameter portion at the tip of the sheet material holding pin 12, as shown in FIG. 10 .

[0020] Here, the "molded portion of the sheet material 3" refers to the portion that is adhered to the parison 2a, and when the integrally molded body 1 is blow-molded as described below, the uneven shape of the cavity surface is transferred to the blow-molded body 2 that is molded, and the sheet material is molded into the desired shape by following the molding surface of the blow-molded body 2.

[0021] The arrangement of the sheet material holding pins 12 in the split molding die 11a is not particularly limited. For example, if the molding portion of the sheet material 3 is rectangular, the pins 12 can be arranged at least at the four corners, and can be designed as appropriate depending on the shape and size of the molding portion of the sheet material 3. In particular, in this embodiment, it is preferable to arrange the sheet material holding pins 12 at intervals appropriately adjusted along the periphery of the molding portion of the sheet material 3 depending on the shape and size of the molding portion of the sheet material 3 so that no tension is applied to the molding portion of the sheet material 3 and the molding portion of the sheet material 3 is held flat without loosening.

[0022] In the illustrated example, the sheet material holding pins 12 are preferably provided only within the cavity surface so that the molded portion of the sheet material 3 is located within the molding surface of the blow-molded body 2, i.e., within the cavity surface. In this embodiment, by appropriately adjusting the arrangement of the sheet material holding pins 12 as needed, the molded portion of the sheet material 3 can be selectively located within any range within the molding surface of the blow-molded body 2. In particular, the manufacturing method of the present invention is advantageous in that the molded portion of the sheet material 3 is not located on the entire molding surface of the blow-molded body 2, but rather by arranging the sheet material holding pins 12 within the cavity surface, it is possible to bond and mold the sheet material 3 only to a specific portion of the blow-molded body 2. In this case, the sheet material holding pins 12 are located inside the parting line of the mold.

[0023] The height of each of the sheet material holding pins 12 can be adjusted individually so that the protruding height decreases from the state in which they protrude from the cavity surface in the mold clamping direction X. In the illustrated example, the protruding height of each of the sheet material holding pins 12 is individually adjustable by attaching the sheet material holding pins 12 to an air cylinder 13 embedded in the molding die 11a, but this is not limiting. As long as the protruding height of the sheet material holding pins 12 can be adjusted to decrease while maintaining a state in which all or part of the formed portion of the sheet material 3 held at the tip end of the sheet material holding pins 12 is held flat and perpendicular to the mold clamping direction X, other means such as a motor-driven power transmission means can also be used.

[0024] When parison 2a is placed between split molding dies 11a, 11b, which are waiting in an open state, the mold clamping operation is initiated, and split molding dies 11a, 11b move toward parison 2a in mold clamping direction X, approaching each other. Accompanying this, sheet material 3 held by sheet material holding pins 12 on one split molding die 11a's side moves in mold clamping direction X together with split molding die 11a. At this time, sheet material holding pins 12 protrude from the cavity surface in mold clamping direction X. Furthermore, it is preferable that the plane of the molding portion of sheet material 3 moving toward parison 2a (the surface portion on the parison side) be maintained in a planar state so as to be perpendicular to mold clamping direction X during this movement.

[0025] In this embodiment, by performing such a mold clamping operation, the flat surface of the molding portion of the sheet material 3 is brought into contact with the softened parison 2a during the mold clamping operation, and the molded portion of the sheet material 3 and the parison 2a are bonded together by utilizing the heat stored in the parison 2a (see FIG. 2). After that, even after the molding portion of the sheet material 3 and the parison 2a are bonded together at their contacting portions, the mold clamping operation is continued, and the split mold 11a is moved toward the parison 2a while the protruding height of the sheet material holding pins 12 is adjusted to be lower (see FIG. 3), and mold clamping is completed (see FIG. 4).

[0026] When adjusting the protruding height of the sheet material holding pins 12 to a low value, it is preferable to adjust the height so that the molded portion of the sheet material 3 remains flat and perpendicular to the mold clamping direction X even after contacting the parison 2a. Furthermore, it is preferable to adjust the height so that the molded portion of the sheet material 3 is pressed against the parison 2a with an appropriate pressure so that the contact area between the molded portion of the sheet material 3 and the parison 2a is well bonded over a wider bonding area. It is preferable that the pressure from the sheet material holding pins 12 on the mold side is balanced with the pressure from the parison 2a due to the blown air, or that the sheet material 3 and the parison 2a are bonded together via a state in which the pressure from the sheet material holding pins 12 is strong. In this case, it is preferable to increase the bonding area between the molded portion of the sheet material 3 and the parison 2a while preventing the molded portion of the sheet material 3 from stretching, reducing its extension, or preventing the sheet material holding pins 12 from piercing the parison 2a. The adhesion area between the molded portion of the sheet material 3 and the parison 2a can be adjusted to be larger by controlling the tensile elongation and tensile modulus of the sheet material 3, the timing for lowering the protruding height of the sheet material holding pins 12, etc. For example, when adhering the molded portion of the sheet material 3 and the parison 2a, air can be blown into the parison 2a to an extent that the volume inside the parison 2a does not expand excessively, thereby preventing wrinkles from forming in the parison 2a, thereby making it possible to increase the adhesion area between the molded portion of the sheet material 3 and the parison 2a.

[0027] To ensure better adhesion between the molded portion of the sheet material 3 and the parison 2a, the tensile elongation of the sheet material 3 is preferably 150% or more, more preferably 170% to 300%, and even more preferably 180% to 250%. The tensile modulus of the sheet material 3 is preferably 0.1 to 1 kPa, more preferably 0.1 to 0.7 kPa, and even more preferably 0.1 to 0.5 kPa. If the protruding height of the sheet material holding pins 12 is lowered too early, wrinkles may form in the molded portion of the sheet material 3 and the parison 2a. The tensile elongation can be measured in accordance with JIS L1913 (2010).

[0028] After the sheet material 3 and parison 2a are brought into contact and bonded, if the mold clamping operation is continued while adjusting the protruding height of the sheet material holding pins 12 to a lower value, the molded portion of the sheet material 3 will partially approach the cavity surface in accordance with the uneven shape of the cavity surface (see FIG. 3). Then, after the height of the sheet material holding pins 12 is lowered and held at that low height, the molded portion of the sheet material 3 will gradually come into contact with the cavity surface, conforming to the uneven shape of the cavity surface. At this time, it is preferable that the sheet material holding pins 12 are retracted into the molding die 11a while still holding the molded portion of the sheet material 3, leaving only the tip side holding the molded portion of the sheet material 3 (see FIGS. 9(b) and 10(b)). On the other hand, in the portion where the cavity surface and the sheet material 3 are not close to each other, the height of the sheet material holding pins 12 is continuously adjusted in conjunction with the mold clamping operation, thereby preventing wrinkles from forming in the sheet material 3 and the parison 2a. Furthermore, at this stage, the sheet material 3 and the parison 2a are bonded together, which effectively prevents wrinkles from forming. In this way, the parison 2a and the sheet material 3 stretch in unison along the uneven shape of the cavity surface, preventing wrinkles from forming. In this way, the parison 2a and the sheet material 3 stretch in unison along the uneven shape of the cavity surface, preventing wrinkles from forming.

[0029] By doing this, it is possible to prevent gaps from occurring between the molded portion of the sheet material 3 and the uneven shape of the cavity surface, and in the final stage of the mold closing operation, the parison 2a can be more completely adhered to the molded portion of the sheet material 3 between the split molding dies 11a, 11b, and the mold closing operation can be completed.

[0030] When the mold clamping operation is complete, the parison 2a to which the sheet material 3 is adhered is sandwiched between the split molds 11a, 11b and confined in the cavity formed between the split molds 11a, 11b (see FIG. 4). Next, in this embodiment, blow air is further blown into the hollow portion of the parison 2a in this state, thereby blow-molding the parison 2a to which the sheet material 3 is adhered together with the sheet material 3. As a result, the molded blow-molded body 2 and the sheet material 3 are integrated, and the uneven shape of the cavity surface is transferred to the molded portion of the sheet material 3, and the molded portion of the sheet material 3 conforms to the molding surface of the blow-molded body 2 to form an integrally molded body 1 molded into the desired shape.

[0031] In the illustrated example, when performing blow molding in this manner, a tubular puncture pin 14 is installed in the other split mold 11b so as to be able to move back and forth along its axial direction. When the puncture pin 14 advances along its axial direction, it penetrates the parison 2a and protrudes into the hollow space within the parison 2a, allowing blow air to be blown through the puncture pin 14 (see FIGS. 5 and 6). The means for blowing blow air into the hollow space within the parison 2a is not particularly limited. The position where the puncture pin 14 is installed is also not particularly limited, but it is preferable to install it so that it penetrates the parison 2a while avoiding the sheet material 3.

[0032] Although not specifically shown, after the integrally molded body 1 is formed, the puncture pin 14 is retracted along the axial direction, and the split molding dies 11a and 11b are moved in the opposite direction to the mold clamping direction X to open the mold, and the integrally molded body 1 to which the sheet material 3 is adhered is removed from the molding die, thereby completing the series of steps. After being removed from the mold, the integrally molded body 1 can be subjected to post-processing such as deburring, if necessary.

[0033] According to the present embodiment, during mold clamping, the molded portion of the sheet material 3 held by the sheet material holding pins 12 is brought into contact with the parison 2a to bond the molded portion of the sheet material 3 and the parison 2a. Thereafter, the protruding height of the sheet material holding pins 12 is adjusted to a low level while the mold clamping is completed. During blow molding, the molded portion of the sheet material 3 conforms well to the parison 2a, and the two can be synchronized to extend integrally along the uneven shape of the cavity surface. As a result, it is possible to manufacture an integrally molded product 1 in which the occurrence of wrinkles is suppressed, especially in the recessed portion of the product where the convex shape of the cavity surface is transferred and molded.

[0034] In addition, in this embodiment, after the integrally molded body 1 is formed or before it is molded, the hollow portion of the blow molded body 2 that has been molded or is in the process of being molded can be filled with expanded beads 4 as described below, and an expanded bead molding can be formed within the blow molded body 2, so that the integrally molded body 1 to be manufactured can be manufactured as a composite containing an expanded bead molding therein.

[0035] In the illustrated example, the other split mold 11b is provided with an expanded bead filling feeder 15 equipped with a perforating means (not shown), such as a rotary blade or a punching blade. Then, a filling port 2b is formed in the blow-molded body 2 by the perforating means (see FIG. 7), and expanded beads 4, which are pressure-fed through the expanded bead filling feeder 15, are filled into the hollow portion of the blow-molded body 2 through the perforated filling port 2b (see FIG. 8). The filling port 2b can be formed in the blow molded body 2 even during molding, as long as the blow molded body 2 is in a state where it can be perforated. After the blow molded body 2 is removed from the mold, it can be placed in another mold capable of producing an expanded bead molded body and molded again.

[0036] When filling the hollow portion of the blow molded body 2 with the expanded beads 4, it is preferable to complete the filling while at least the inner surface of the blow molded body 2 is in a softened state. A preferred filling method is a so-called compression filling method, in which the pressure inside the hollow portion of the blow molded body 2 is adjusted to be higher than atmospheric pressure, the expanded beads 4 are compressed by applying a pressure higher than the pressure inside the hollow portion of the blow molded body 2, and the pressure inside the hollow portion of the blow molded body 2 is released after filling is complete. When the process includes a step of filling the expanded beads 4, the parison 2a is easily cooled by filling with the expanded beads 4, so it is particularly important to bond the parison 2a to the sheet material 3 before mold clamping is completed.

[0037] After the filling is completed, a heating medium is supplied into the blow-molded body 2 through the puncture pin 14 to cause secondary expansion of the expanded beads 4 and heat-fuse the beads together to form an expanded bead molding. Steam is usually used as the heating medium. The vapor pressure of the steam is preferably 0.15 MPa to 0.6 MPa (G), more preferably 0.18 MPa to 0.5 MPa (G).

[0038] In producing the integrally molded body 1 as a composite containing an expanded bead molding therein, the expanded beads 4 can be produced by a known method for producing this type of expanded beads, preferably using the same or the same resin as the thermoplastic resin (A) used in the blow molded body 2, so that the expanded bead molding formed in the blow molded body 2 will adhere well to the inner surface of the blow molded body 2. For example, when the thermoplastic resin (A) is a polyolefin resin, the expanded beads are preferably also a polyolefin resin, and when the thermoplastic resin (A) is a polypropylene resin, the expanded beads are preferably also a polypropylene resin.

[0039] The apparent density of the expanded beads 4 is not particularly limited, but is preferably a commonly used apparent density of 0.018 to 0.3 g / cm. 3In order to easily control the secondary expansion performance by steam, the apparent density of the expanded beads 4 is 0.022 to 0.15 g / cm. 3 It is more preferable that: Furthermore, in consideration of ease of filling through the filling port 2b formed in the blow molded body 2, the particle size of the expanded beads 4 is preferably 1 to 6 mm, more preferably 2 to 5 mm. [Example]

[0040] The present invention will be described in more detail below with reference to specific examples.

[0041] [Examples 1 to 4] A polypropylene resin (manufactured by Japan Polypropylene Corporation; EC9GD, MFR = 0.5 g / 10 min, melting point 166 ° C) was used as the thermoplastic resin (A). The parison was extruded downward from the die and softened, and placed between the split molds (between the molds). The extruder temperature was set to 220 ° C and the die temperature to 190 ° C, and the melt of the thermoplastic resin (A) was extruded. The circumferential length of the parison was adjusted to 900 mm when the melt of the thermoplastic resin (A) was extruded from the die. In addition, the molded portion of the sheet material was held in place by multiple sheet material holding pins installed on one of the split molds, which was waiting in the mold open state and protruding from the cavity surface in the mold clamping direction. The sheet material used was nonwoven fabric cut to a length of 1200 mm and a width of 1100 mm. The pins for holding the sheet material had a protruding height of 60 to 135 mm, and were arranged with a height difference corresponding to the unevenness of the cavity surface so that the molding part of the sheet material was held parallel to the extrusion direction of the parison. There were eight pins for holding the sheet material, and the area of ​​the sheet material per pin in the molding part was 1650 cm. 2 In addition, there was a 3500cm area in the center of the cavity surface. 2 A trapezoidal convex molding part with a height of 120 mm was formed in an area (500 mm long x 700 mm wide), and the concave part of the product was formed by the convex molding part. The material composition (thermoplastic resin (B)), basis weight, tensile elongation, and tensile modulus of elasticity of the nonwoven fabrics used in Examples 1 to 4 are shown in Table 1. Note that the tensile elongation and tensile modulus are the average values ​​of the values ​​measured along the MD direction and the values ​​measured along the TD direction.

[0042] [Table 1]

[0043] Next, the mold clamping operation was started, and the sheet material was moved in the mold clamping direction together with the split molding mold, so that the protruding height of the sheet material holding pin was at its highest, and the molded portion of the sheet material was abutted against the parison, thereby bonding the molded portion of the sheet material and the parison together. The mold temperature at this time was 60°C, and the surface temperature of the parison immediately before clamping was 170 to 190°C. The mold clamping operation was continued thereafter, and the protruding height of the sheet material holding pin was adjusted to a lower level until the mold clamping was completed. The parison with the adhered sheet material was then blow molded together with the sheet material to form an integrally molded body in which the sheet material was adhered to a part of the blow molded body. The blow pressure was 0.3 MPa (G) to form the shape of the mold.

[0044] [Examples 5 to 8] In forming an integrally molded article in which a sheet material was bonded to a portion of a blow-molded article through the same steps as in Examples 1 to 4, an expanded particle filling feeder and 20 steam pins (steam inlet / outlet pipes) were inserted into the hollow portion of the softened blow-molded article, penetrating its wall. Then, gas was supplied and exhausted from the steam pins to the hollow portion of the blow-molded article, and the pressure inside the hollow portion of the blow-molded article was adjusted to 0.15 MPa (G), while expanded particles (expanded propylene-based resin particles; bulk density 30 g / L, melting point 148°C) were filled into the hollow portion of the blow-molded article through the filling feeder.

[0045] After the expansion beads were filled, suction was applied from 10 of the 20 steam pins inserted into the hollow portion of the blow-molded body, while steam at 0.40 MPa (G) was supplied from 10 steam pins B into the hollow portion of the blow-molded body for 20 seconds. Next, suction was applied from steam pin B, while steam at 0.40 MPa (G) was supplied from steam pin A into the hollow portion of the blow-molded body for 20 seconds. Next, steam at 0.40 MPa (G) was supplied from all steam pins into the hollow portion of the blow-molded body for 20 seconds. This steam heating caused secondary expansion of the expansion beads, fused the expansion beads together, and further fused the inner surface of the blow-molded body to the expansion bead molding, forming an expansion bead molding within the blow-molded body and integrating the blow-molded body with the expansion bead molding. After the foamed molded article had cooled, the filling feeder and steam pin were removed from the foamed molded article, the mold was opened, and an integrally molded article with flash, which was molded as a composite containing the foamed bead molded article inside, was taken out. The flash portion of this integrally molded article was removed to obtain an integrally molded article as a product.

[0046] When the formed integrally molded body was visually observed, no wrinkles were found in the sheet material in any of Examples 1 to 8.

[0047] The present invention has been described above by showing preferred embodiments, but it goes without saying that the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the present invention.

[0048] For example, in the above-described embodiment, an example was given in which the molded portion of the sheet material held by the sheet material holding pin installed on one side of the split molding mold was molded integrally with the blow molded body, but it is also possible to install a sheet material holding pin on the other split molding mold and adhere the sheet material to both opposing sides of the blow molded body to produce an integrally molded body. [Explanation of symbols]

[0049] 1. Integral molding 2. Blow-molded body 2a Parison 3 Sheet material 4. Foam particles 10 Die 11a,11b split mold 12 Sheet material holding pin X Mold clamping direction

Claims

1. A method for producing an integrally molded article in which a sheet material is bonded to a part of a blow-molded article made of a thermoplastic resin (A), comprising: a step of extruding the melt of the thermoplastic resin (A) downward through a die to form a softened parison, which is then placed between two split molds; a step of holding a molded portion of the sheet material with a plurality of sheet material holding pins installed so as to protrude from the cavity surface of the split mold in the mold clamping direction, and moving the sheet material together with the split mold in the mold clamping direction to bring the molded portion of the sheet material into contact with the parison and bond the molded portion of the sheet material to the parison; a step of completing mold clamping while adjusting the protruding height of the sheet material holding pin to a low level; Blow molding the parison to which the sheet material is bonded together with the sheet material; a step of removing the integrally molded body obtained by blow molding, in which the sheet material is adhered to a part of the blow molded body, from the mold; A method for producing an integrally molded body, comprising:

2. The method for manufacturing an integrally molded article according to claim 1 , wherein the sheet material is a woven fabric or a nonwoven fabric.

3. The method for producing an integrally molded article according to claim 1 or 2, wherein the thermoplastic resin (A) is a polyolefin-based resin.

4. The method for producing an integrally molded body according to claim 3, wherein the sheet material is made of a thermoplastic resin (B), and the thermoplastic resin (B) includes a polyolefin resin.

5. 3. The method for manufacturing an integrally molded product according to claim 1, wherein the sheet material holding pins are provided only within the cavity surface of the split mold.

6. 3. The method for producing an integrally molded body according to claim 1, further comprising the steps of: blow-molding the parison to which the sheet material is adhered together with the sheet material; filling the hollow portion of the blow-molded body obtained by blow-molding with foamed beads; and supplying a heating medium into the blow-molded body to heat-fuse the foamed beads to each other to form a foamed bead molded body.

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