Aromatic polyester resin foam-molded article and method for producing same

Abstract

An object of the present invention is to provide an aromatic polyester-based resin foam-molded article for a core material having a high thermal dimensional change rate and a method for producing the same.SOLUTION: The present invention provides an aromatic polyester-based resin expanded molded article for a core material of a composite structural member, wherein the expanded molded article contains 90% by mass or more of polyethylene terephthalate, the expanded molded article has a surface crystallinity of 3 to 20% as measured by a differential scanning calorimeter (DSC), and the expanded molded article has a thermal dimensional change rate of 1 to 10% after the expanded molded article is allowed to stand in a thermostatic chamber at 130 °C for 168 hours.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an aromatic polyester resin foam molded article and a method for producing the same. [Background technology]

[0002] In-mold foam molded articles are used as core materials for composite structural members due to their advantages such as light weight and heat insulation. A method for producing in-mold foam molded articles involves filling the cavity of a mold with foamed beads, heating the foamed beads to expand, and then thermally fusing the expanded beads together using the expansion pressure to produce a foam having a desired shape (sometimes referred to as the bead expansion molding method). A known bead expansion molding method involves heating and expanding the foamed beads filled in the mold cavity by introducing a heating medium such as steam into the mold cavity (the steam heating method). In the steam heating method, a slit is provided in the mold to allow the heating medium such as steam to be introduced into the mold cavity. This results in slit marks on the surface of the resulting molded article (Patent Document 1).

[0003] Another method reported for producing an in-mold foamed article involves extrusion foaming of a molten resin raw material into which a foaming agent has been injected to produce a cylindrical molded article, which is then cut open into a sheet-like shape and used as a core material (Patent Document 2).

[0004] When a foamed molded article is used as a core material, the slit marks can prevent the core material from being integrated with the skin material. Furthermore, depending on the type and thickness of the skin material and the conditions for compounding, small protrusions caused by the slit marks can be formed on the surface of the composite structural member, which can impair the surface smoothness of the composite structural member.

[0005] In the method of producing a cylindrical molded product by extrusion foam molding and then cutting it open to form a sheet, no slit marks are left, but it is difficult to produce a thick core material and an additional step of forming the product into a sheet after foam molding is required. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-080022 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-069460 Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention is to provide an aromatic polyester resin foam molded product for use as a core material for a composite structural member, which has no slit marks on its surface (preferably the surface onto which a skin material is to be laminated, more preferably the surface onto which a skin material is to be laminated and which has the largest area, and even more preferably the surface onto which a skin material is to be laminated and which has the largest area, excluding areas corresponding to the end areas in a plan view), and a method for producing the same. An object of the present invention is to provide an aromatic polyester resin foam molded product for use as a core material for a composite structural member, which has a small maximum peak height (Sp) on its surface (preferably the surface on which a skin material is to be laminated, more preferably the surface on which a skin material is to be laminated and which has the largest area, and even more preferably the surface on which a skin material is to be laminated and which has the largest area, excluding areas corresponding to the end areas in a plan view), and a method for producing the same. An object of the present invention is to provide a method for producing an aromatic polyester resin foam molded article for use as a core material for a composite structural member, which method enables the production of a core material having a greater thickness than a sheet. An object of the present invention is to provide an aromatic polyester resin foam molded article for use as a core material, which has a high rate of thermal dimensional change, and a method for producing the same. [Means for solving the problem]

[0008] The present inventors have found that by immersing a molding die containing the foamed beads (the molding die has vent holes on the side leading to the molding space) in hot water to expand the foamed beads, it is possible to obtain a foamed molded product for use as a core material of a composite structural member, which has a surface free of slit marks and a small maximum peak height (Sp) (preferably the surface onto which a skin material is to be laminated, more preferably the surface onto which a skin material is to be laminated and which has the largest area, and even more preferably the surface onto which a skin material is to be laminated and which has the largest area excluding the areas corresponding to the end areas in plan view), and which has a high rate of dimensional change upon heating, despite being manufactured by a bead expansion molding method.

[0009] The present invention typically includes the following aspects. Section 1. An aromatic polyester resin foam molded article for use as a core material of a composite structural member, The foamed molded body contains 90% by mass or more of polyethylene terephthalate, The foamed molded article has a surface crystallinity of 3 to 20% as measured by a differential scanning calorimeter (DSC), the foamed molded body has a thermal dimensional change rate of 1 to 10% after being left to stand in a thermostatic bath at 130°C for 168 hours; Foam molding. Section 2. Item 2. The foam molded article according to Item 1, wherein the maximum peak height (Sp) of the surface of the foam molded article is 0.70 mm or less. Section 3. Item 3. The foamed molded article according to item 1 or 2, wherein the fusion rate of the expanded particles constituting the foamed molded article is 0 to 10%. Section 4. Item 4. A composite structural member comprising the foam molded article according to any one of items 1 to 3 as a core material. Section 5. A method for producing a foam molded article, comprising the steps of: producing an aromatic polyester resin foam molded article using a mold having a molding space for molding the foam molded article; a first step of placing foamed aromatic polyester resin particles in the molding space of the mold and closing the mold; and a second step in which the closed mold is immersed in hot water at 90 to 100°C to introduce the hot water into the mold, thereby foaming and heat-sealing the foamed particles contained in the mold, thereby forming the foamed molded article; Including, the mold has a vent hole on a side surface thereof that communicates with the molding space; The immersion treatment is carried out for an immersion time such that the value calculated by multiplying the hot water temperature (°C) by the immersion time (minutes) is 600 to 3000 when the hot water temperature is 90°C or higher but lower than 95°C, and such that the value calculated by multiplying the hot water temperature (°C) by the immersion time (minutes) is 400 to 950 when the hot water temperature is 95 to 100°C, The foamed molded body contains 90% by mass or more of polyethylene terephthalate, The foamed molded article has a surface crystallinity of 3 to 20% as measured by a differential scanning calorimeter (DSC), the foamed molded body has a thermal dimensional change rate of 1 to 10% after being left to stand in a thermostatic bath at 130°C for 168 hours; A method for producing a foamed molded article. Section 6. Item 6. The method for producing a foam molded article according to Item 5, wherein the foam molded article has a maximum peak height (Sp) on the surface of the foam molded article of 0.70 mm or less. Section 7. Item 7. The method for producing a foamed molded article according to Item 5 or 6, wherein the fusion rate of the foamed beads constituting the foamed molded article is 0 to 10%.

[0010] The present invention may include the following aspects. Section 8. Item 4. A core material for a composite structural member comprising the aromatic polyester resin foam molded article according to any one of Items 1 to 3. Section 9. Item 9. A composite structural member comprising the core material according to item 8. [Effects of the Invention]

[0011] The present invention provides an aromatic polyester resin foam molded article for use as a core material for a composite structural member, which has no slit marks on its surface (preferably the surface on which a skin material is to be laminated, more preferably the surface on which a skin material is to be laminated and which has the largest area, and even more preferably the surface on which a skin material is to be laminated and which has the largest area and which excludes the area corresponding to the edge area in plan view) and has a small maximum peak height (Sp), and a method for producing the same. By using this foam molded article as a core material, a composite structural member can be produced that does not have unevenness on the surface of the skin material due to slit marks, even when a thin skin material is used. The present invention provides an aromatic polyester resin foam molded article for use as a core material for a composite structural member, which has a high rate of dimensional change upon heating, and a method for producing the same. When the foam molded article is laminated with a skin material and heated to produce a composite structural member, the foam molded article increases in size due to heating. As the size of the foam molded article increases, the foam molded article presses against the skin material, resulting in better integration between the foam molded article and the skin material. According to the present invention, a method for producing an aromatic polyester resin foam molded article for use as a core material for a composite structural member can be provided, which requires simpler equipment and less energy during foam molding than methods such as steam heating, in which a molding mold having vent holes containing foamed beads is immersed in hot water to heat and foam the foamed beads in the mold using steam. [Brief explanation of the drawings]

[0012] [Figure 1] 1A is a perspective view of a foam molded body, and FIG. 1B is a front view and a plan view of the foam molded body, illustrating the surface that is the target for measuring the maximum peak height (Sp). [Figure 2] 1 is a schematic perspective view showing a foam molded article according to one embodiment. [Figure 3] FIG. 2 is a schematic perspective view showing a molding die used in one embodiment. [Figure 4] 1 is a schematic diagram showing one embodiment of a method for producing a foamed molded article. [Figure 5] FIG. 2 is a cross-sectional view illustrating a manufacturing apparatus used to obtain expanded beads in the examples. [Figure 6]FIG. 2 is a cross-sectional view illustrating a manufacturing apparatus used to obtain expanded beads in the examples. [Figure 7] FIG. 2 is a cross-sectional view illustrating a manufacturing apparatus used to obtain expanded beads in the examples. DETAILED DESCRIPTION OF THE INVENTION

[0013] As used herein, the phrase "comprising" is intended to encompass the phrases "consisting essentially of" and "consisting of."

[0014] In this specification, with regard to numerical ranges, "to" means greater than or equal to the leftmost numerical value and less than or equal to the rightmost numerical value. For example, "0.5 to 10% by weight" and "0.5% by mass to 10% by weight" both mean "0.5% by weight or greater and 10% by weight or less." Furthermore, with regard to numerical ranges, "greater than or equal to" means "the same as or greater than," and "less than or equal to" means "the same as or less than."

[0015] In the numerical ranges described herein, the upper or lower limit of a certain numerical range can be arbitrarily combined with the upper or lower limit of another numerical range described in the same paragraph or another step. In addition, in a certain numerical range described herein, the upper or lower limit of that numerical range can be replaced with a value shown in an example or a value that can be unambiguously derived from an example.

[0016] (Aromatic polyester resin foam molding) The aromatic polyester resin foam molded article of the present invention is a fused body of expanded aromatic polyester resin beads. More specifically, it is a molded article in which a plurality of expanded aromatic polyester resin beads are thermally fused together to form an integrated body. The aromatic polyester resin foam molded article may contain 90% by mass or more of an aromatic polyester resin. In this specification, a molded article molded by heating and expanding expanded beads in a mold is also referred to as a bead foam molded article.

[0017] (aromatic polyester resin) The aromatic polyester resin may be a polyester containing an aromatic dicarboxylic acid component and a diol component, and examples thereof include polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polycyclohexanedimethylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, etc., with polyethylene terephthalate being preferred. The aromatic polyester resins may be used alone or in combination of two or more.

[0018] In addition to the aromatic dicarboxylic acid component and the diol component, the aromatic polyester resin may contain, as constituent components, for example, tricarboxylic acids such as trimellitic acid, tetracarboxylic acids such as pyromellitic acid, and other polycarboxylic acids having three or more valences, anhydrides thereof, triols such as glycerin, and polyhydric alcohols having three or more valences, such as tetraols such as pentaerythritol.

[0019] The aromatic polyester resin may include a modified aromatic polyester resin crosslinked by a crosslinking agent. As the crosslinking agent, a known agent may be used, for example, an acid dianhydride such as pyromellitic anhydride, a polyfunctional epoxy compound, an oxazoline compound, an oxazine compound, etc. The crosslinking agent may be used alone or in combination of two or more.

[0020] When the aromatic polyester resin is modified by crosslinking with a crosslinking agent, the aromatic polyester resin and the crosslinking agent are supplied to an extruder during the production of expanded aromatic polyester resin particles, and the aromatic polyester resin is crosslinked with the crosslinking agent in the extruder. The amount of the crosslinking agent supplied to the extruder is preferably 0.01 to 5 parts by mass, more preferably 0.1 to 1 part by mass, per 100 parts by mass of the aromatic polyester resin, from the viewpoint of performing extrusion foaming well.

[0021] The mass average molecular weight (Mw) of the aromatic polyester resin is preferably 45,000 to 100,000, more preferably 60,000 to 90,000, in order to provide excellent extrusion foamability and excellent secondary foamability of the resulting expanded beads. When the aromatic polyester resin constituting the expanded beads is a modified aromatic polyester resin, the mass average molecular weight (Mw) of the aromatic polyester resin means the mass average molecular weight of the modified aromatic polyester resin.

[0022] The mass average molecular weight (Mw) of the aromatic polyester resin means the mass average molecular weight measured using gel permeation chromatography (GPC) in terms of polystyrene (PS). Specifically, the mass-average molecular weight is measured as follows: 0.5 mL of hexafluoroisopropanol (HFIP) and 0.5 mL of chloroform are added to 5 mg of sample, in that order, and dissolved (immersion time: 6.0 ± 1.0 hours (complete dissolution)) to obtain a sample solution. After confirming that the sample is completely dissolved in the solution, chloroform is added to the sample solution to dilute it to a volume of 10 mL, and the solution is shaken and mixed. The sample solution is filtered through a non-aqueous 0.45 μm syringe filter manufactured by Shimadzu GLC Corporation to obtain a filtrate. The filtrate is measured using a chromatograph under the following measurement conditions. The mass-average molecular weight (Mw) is determined from a previously prepared standard polystyrene calibration curve. Equipment used: Tosoh Corporation "HLC-8320GPC EcoSEC" gel permeation chromatograph (with built-in RI and UV detectors) (GPC measurement conditions) column Sample side Guard column = Tosoh Corporation TSK guard column HXL-H (6.0 mm x 4.0 cm) x 1 Measurement column: Tosoh Corporation TSKgel GMHXL (7.8 mm I.D. x 30 cm) x 2 in series Reference side Resistance tube (inner diameter 0.1 mm x 2 m) x 2 in series Column temperature = 40°C Mobile phase = chloroform Mobile phase flow rate Sample pump: 1.0 mL / min Reference pump = 0.5 mL / min Detector: UV detector Wavelength: 254nm Injection volume: 15μL Measurement time: 10 to 32 minutes Runtime: 20 min Sampling pitch: 500 msec The standard polystyrene samples used for the calibration curve were "STANDARD SM-105" and "STANDARD SH-75" manufactured by Showa Denko K.K., with mass-average molecular weights of 5,620,000, 3,120,000, 1,250,000, 442,000, 151,000, 53,500, 17,000, 7,660, 2,900, and 1,320. The polystyrene standards for the calibration curve were divided into groups A (5,620,000, 1,250,000, 151,000, 17,000, 2,900) and B (3,120,000, 442,000, 53,500, 7,660, 1,320). Then, 2 mg, 3 mg, 4 mg, 4 mg, and 4 mg of A were weighed and dissolved in 30 mL of chloroform. Similarly, 3 mg, 4 mg, 4 mg, 4 mg, and 4 mg of B were weighed and dissolved in 30 mL of chloroform. The polystyrene standards were then prepared by injecting 50 μL of each of the prepared solutions A and B, and creating a calibration curve (cubic equation) from the retention times obtained after measurement. The mass-average molecular weight was calculated using the calibration curve.

[0023] The crystallinity of the surface of the foamed molded article may be 3 to 20%, 4 to 20%, 5 to 20%, etc., preferably 6 to 20%, more preferably 6 to 18%. The crystallinity of the foamed molded article is determined by the methods described in JIS K7122:1987 and JIS K7122:2012, and more specifically, by the methods described in the Examples.

[0024] The maximum peak height (Sp) of the surface of the aromatic polyester resin foam molded article may be 0.70 mm or less, 0.65 mm or less, 0.60 mm or less, 0.58 mm or less, etc. The maximum peak height (Sp) of the surface may be 0.01 to 0.70 mm, 0.01 to 0.65 mm, 0.01 to 0.60 mm, 0.01 to 0.58 mm, etc., preferably 0.1 to 0.70 mm, more preferably 0.1 to 0.65 mm, even more preferably 0.1 to 0.60 mm, and particularly preferably 0.1 to 0.58 mm. The maximum peak height (Sp) is determined by a method using a measuring device in accordance with ISO 25178, and more specifically, by the method described in the Examples.

[0025] The surface to be measured for the maximum peak height (Sp) is preferably a surface onto which a skin material is to be laminated, and is the surface, in a projection (plan view) with that surface facing up, excluding the area from the long side of the projection view to a length equivalent to 10% of the average length of the long and short sides of the projection view (the sum of the long side length and the short side length divided by 2) and the area from the short side of the projection view to a length equivalent to 10% of the average length of the long and short sides of the projection view (also referred to in this specification as the "surface excluding the area corresponding to the end area in the plan view"); more preferably, it is the surface with the largest area onto which a skin material is to be laminated, excluding the area corresponding to the end area in the plan view.

[0026] The surface excluding the area corresponding to the plan view edge area will be explained based on Figure 1. Figure 1 shows a perspective view (A), a front view, and a plan view (B) of a foam molded article. The length of the long side E1 in the plan view is 20 cm, and the length of the short side E2 is 10 cm. The average length of the long side E1 and the short side E2 is 15 cm, and 10% of that is 1.5 cm. The area extending from the long side E1 to 1.5 cm is area F1, and the area extending from the short side E2 to 1.5 cm is area F2. Areas F1 and F2 are the "plan view edge area." The area excluding areas F1 and F2 from the plan view is area F3 (17 cm x 7 cm). The surface f3 of the foam molded article corresponding to area F3 is the "surface excluding the area corresponding to the plan view edge area." Furthermore, in Figure 1, the "area corresponding to the plan view edge area" refers to areas f1 and f2 on the surface, which correspond to areas F1 and F2.

[0027] The aromatic polyester resin foam molded product is a thermally fused product of foamed beads. The fusion rate of the foamed beads that make up the interior of the thermally fused product (i.e., the foamed beads inside the foam molded product) can be 0 to 20%, 0 to 10%, or 0 to 5%. The fusion rate can be determined by counting the breaks of 150 foamed beads within an arbitrary area on the fracture surface of a foam molded product measuring 200 mm x 200 mm x 10 mm thick, which is divided into two parts; in detail, it is determined by the method described in the Examples.

[0028] The thermal dimensional change rate of an aromatic polyester resin foam molded article after being left to stand in a constant temperature bath at 130°C for 168 hours can be 1 to 10%, preferably 1 to 8%, and more preferably 1 to 7%. When the thermal dimensional change rate is 1% or more, when the foam molded article is used as the core material of a composite structural member, heating during the combination of the core material and the skin material causes the core material to expand and press against the skin material, which is advantageous for integrating the core material and the skin material. The thermal dimensional change rate is determined by the method described as Method B in JIS K 6767:1999 "Foamed plastics - Polyethylene - Test methods," and more specifically, by the method described in the Examples.

[0029] (Method of manufacturing an aromatic polyester resin foam molded product) In the method for producing an aromatic polyester resin foam molded article of the present invention, a mold (having a vent hole on the side leading to the molding space) containing foamed beads is immersed in hot water (preferably hot water at 90 to 100°C) to introduce hot water into the mold and foam the foamed beads contained in the mold. This method is superior to a steam heating method in which the foamed beads in the mold are heated and foamed by steam introduced into the mold through a slit in the mold. This method provides advantages over a steam heating method in which the foamed beads in the mold are heated and foamed by steam introduced into the mold through a slit in the mold. This method provides no slit marks on the surface of the foam molded article (preferably the surface on which a skin material is to be laminated, more preferably the surface on which a skin material is to be laminated and having the largest area, and even more preferably the surface on which a skin material is to be laminated and having the largest area, excluding the area corresponding to the end area in plan view), requires simple equipment for foam molding, and requires less energy for foam molding. This production method is suitable for producing the aromatic polyester resin foam molded article of the present invention by using hot water heating.

[0030] One embodiment of the method for producing an aromatic polyester resin foam molded article of the present invention is a method for producing an aromatic polyester resin foam molded article using a mold having a molding space for molding the foam molded article, a first step of placing foamed aromatic polyester resin particles in the molding space of the mold and closing the mold; and a second step in which the closed mold is immersed in hot water at 90 to 100°C to introduce the hot water into the mold, thereby foaming and heat-sealing the foamed particles contained in the mold, thereby forming the foamed molded article; Includes.

[0031] In the manufacturing method of the present invention, the forming mold may have a vent hole on the side surface that leads to the forming space. By having the vent hole, hot water can be introduced into the forming mold through the vent hole during the hot water immersion treatment in the second step. In the production method of the present invention, the foam molded article may be the aromatic polyester resin foam molded article of the present invention. In the production method of the present invention, the foamed molded article may contain 90% by mass or more of polyethylene terephthalate. In the production method of the present invention, the foamed molded article may have a surface crystallinity of 3 to 20% as measured by a differential scanning calorimeter (DSC). In the production method of the present invention, the maximum peak height (Sp) on the surface of the foamed molded article may be 0.70 mm or less. In the production method of the present invention, the foam-molded article may have a thermal dimensional change rate of 1 to 10% after being left to stand in a thermostatic bath at 130°C for 168 hours. In the production method of the present invention, the fusion rate of the expanded beads that constitute the expanded molded article can be 0 to 10%.

[0032] In the first step, the expanded beads are placed in the molding space of the mold and the mold is closed. In the second step, the closed mold is immersed in hot water (preferably hot water at 90 to 100°C) to introduce the hot water into the mold, and the expanded beads placed in the mold are expanded and heat-fused, thereby producing an expanded molded article having a shape corresponding to the shape of the molding space of the mold.

[0033] In the first step, a mold that contains expanded beads and is closed is prepared. This step can be carried out in the same manner as in the process of containing expanded beads and closing the mold in conventional expansion molding using a steam heating method.

[0034] The molding die is usually a pair of two mold members, a male mold and a female mold, which can be opened and closed freely, and the molding space is formed when the mold is closed. The molding die may have vent holes on the side that lead to the molding space.

[0035] In the second step, the closed mold containing the expanded beads is immersed in hot water, and the hot water is introduced into the mold, thereby heating the expanded beads contained in the mold and causing them to expand and heat-seal. By having vent holes on the side of the mold, the mold can be immersed in hot water with at least one vent hole facing upward during the immersion treatment in the second step, allowing hot water outside the mold to be introduced into the molding space of the mold during foam molding. The immersion treatment may be carried out in any manner as long as hot water is placed in a suitable container, the mold is immersed in the hot water, and the expanded particles are expanded and heat-sealed. For example, the entire mold may be immersed in a container filled with hot water. The container for the hot water may be equipped with a device for adjusting the temperature of the hot water.

[0036] When the hot water temperature for the immersion treatment is 90°C or higher but lower than 95°C, the immersion time can be set so that the value calculated by multiplying the hot water temperature (°C) by the immersion time (minutes) is 600 to 3000, and an immersion time of 900 to 2000 is preferred because it results in a large rate of thermal dimensional change.

[0037] When the hot water temperature is 95 to 100°C, the immersion treatment can be carried out for an immersion time such that the value calculated by multiplying the hot water temperature (°C) by the immersion time (minutes) is 400 to 950.

[0038] If the temperature of the hot water fluctuates during the soaking process, the average temperature of the hot water during the soaking process is used as the hot water temperature (°C) in calculating the value obtained by multiplying the hot water temperature (°C) by the soaking time (minutes).

[0039] When the hot water temperature and immersion time for the immersion treatment are within the above ranges, the surface smoothness of the foamed molded article is improved, the maximum peak height (Sp) of the surface is reduced, and the degree of crystallinity can be kept low, which is advantageous in that the rate of dimensional change upon heating is increased.

[0040] In the following, an embodiment of the manufacturing method of the present invention will be described, mainly taking as an example the case of manufacturing a plate-shaped expanded molded bead product 100 (length 200 mm, width 200 mm, thickness 10 mm) as shown in Figure 2. The description is not limited to this embodiment, but can also be applied to other embodiments. As shown in FIG. 2, the expanded bead molded article 100 of this embodiment is formed by a plurality of expanded aromatic polyester resin particles 60 that are thermally fused together after expansion. The expanded aromatic polyester resin particles 60 and the expanded bead molded article 100 of this embodiment each contain 90% by mass or more of aromatic polyester resin.

[0041] The expanded molded beads 100 of this embodiment has a flat plate shape as shown in FIG. 21, and the up-down direction in FIG. 2 will hereinafter also be referred to as the thickness direction D1. In the following description, the left-right direction in FIG. 2 will also be referred to as a width direction D2, and the depth direction in FIG. 2 will also be referred to as a length direction D3. The foamed bead molded article 100 shown in FIG. 2 may have either or both of its upper and lower surfaces as surfaces onto which a skin material is to be laminated. The expanded bead molded body 100 of this embodiment is a molded product produced using a mold, and the thickness direction D1 coincides with the opening and closing direction of the mold. The molding die used in this embodiment has a pair of mold members arranged opposite each other, and is configured so that the molding space can be opened and closed and the volume of the molding space can be changed by moving the pair of mold members closer to and away from each other.

[0042] A method for producing an aromatic polyester resin foam molded article will be described with reference to Figures 3 and 4. Details of the molding die M are shown in Figure 3. The molding die M is closed by placing the aromatic polyester resin foam particles 60' inside its female die Ma and covering the female die Ma with the male die Mv (first step). Next, the mold M is immersed in hot water of a predetermined temperature for a predetermined time in a container (not shown) equipped with a temperature control device containing hot water in an amount sufficient to immerse the mold M, thereby bringing the expanded aromatic polyester resin particles 60' in the mold M into contact with the hot water, causing the expanded aromatic polyester resin particles 60' in the mold M to expand and heat-seal, thereby producing a foamed molded product (second step).

[0043] Fig. 4 illustrates the behavior of the expanded aromatic polyester resin beads 60' in the mold M. In Fig. 4, in order to focus on the relationship between the mold M, the expanded beads 60', and the expanded bead molded body 100, other items used for the immersion treatment, such as hot water and a container containing hot water, are not shown. The expanded aromatic polyester resin beads 60' filled into the mold can be prepared according to a general method for producing expanded beads used in bead expansion molding. For example, an aromatic polyester resin material containing polyethylene naphthalate and polyethylene terephthalate, and optionally a crosslinking agent, can be supplied to an extruder, melt-kneaded in the presence of a foaming agent to prepare a molten mixture, extruded and foamed to prepare an extruded foam, and then cut into expanded beads (also referred to as pre-expanded beads).

[0044] The manufacturing method of this embodiment includes a step S1 of supplying an aromatic polyester resin material, and optionally a crosslinking agent, to an extruder, melt-kneading the material in the presence of a foaming agent to prepare a molten kneaded mixture, extruding and foaming the molten kneaded mixture to prepare an extruded foam, and cutting the extruded foam to obtain foamed particles (also referred to as pre-expanded particles) 60′; a step S2 of preparing a mold M (FIG. 3) having a molding space Mv corresponding to the shape of the expanded bead molded article 100 to be produced (in this embodiment, a "plate shape") and vent holes V (the opening shape and cross-sectional shape of the hole are rectangular, 1 mm high and 100 mm long) penetrating from the molding space Mv to the outside of the mold, and placing a plurality of expanded beads 60' in the molding space Mv of the mold M; a step S3 of closing the molding die M (by closing the molding die M, the plurality of expanded beads 60' accommodated in the molding space Mv may be pressurized with a molding material, and the expanded beads 60' may be compressed); a step S4 of heating the plurality of foamed beads 60′ accommodated in the molding space Mv; A step S5 in which the foamed beads 60 that have been expanded by heating and thermally fused to each other are filled into the molding space Mv to form a foamed bead body 100 having a shape corresponding to the molding space Mv inside the molding die M; Step S6 of cooling the mold M to cool the expanded bead molded body 100 therein is then carried out.

[0045] As described above, in the method for producing a bead foam molded body of this embodiment, a bead foam molded body 100 in which a plurality of expanded beads 60 are heat-fused to one another is produced using a molding mold M equipped with a molding space Mv and vent holes V for molding the bead foam molded body 100. In this embodiment, when the expanded beads 60' are heated, the molding mold M containing the expanded beads 60' is immersed in hot water. By using a molding mold M equipped with vent holes V, hot water can be introduced into the molding space Mv during immersion. The use of such a heating method is advantageous in that there are no slit marks on the surface of the foam molded body, the maximum peak height (Sp) on the surface is small, and the rate of dimensional change due to heating is large.

[0046] The molding die M used in this embodiment has a pair of mold members arranged to face each other, and is configured so that the molding space can be opened and closed and the volume of the molding space can be changed by moving the pair of mold members closer to and away from each other (Figure 3). More specifically, the forming mold M used in this embodiment includes a female mold Ma and a male mold Mb that are arranged facing each other in the vertical direction so that the mold mating surface MP is a horizontal plane. That is, the forming mold M of this embodiment is configured so that the up-down direction is the opening and closing direction.

[0047] The female mold Ma is arranged below the mold mating surface MP, and has a storage recess Ma1 that is recessed downward from the mold mating surface MP at a position corresponding to the center of the mold mating surface MP and opens upward (toward the male mold Mb), and is configured to be able to store resin foam particles (foam particles 60') before heat fusion in the storage recess Ma1. The female mold Ma has a vent hole V penetrating its side wall, which allows hot water outside the molding mold M to be introduced into the molding space Mv during foam molding.

[0048] The male mold Mb is disposed above the mold mating surface MP and has a protrusion Mb1 that protrudes downward (toward the female mold Ma) from the mold mating surface MP at a position corresponding to the center of the mold mating surface MP.

[0049] The cross-sectional shape of the protruding portion Mb1 of the male mold Mb in a horizontal plane is the same from the base end (upper end) in the protruding direction to the tip end (lower end), and in this embodiment is a quadrangular prism. The shape of the space formed in the accommodating recess Ma1 of the female mold Ma has a cross-sectional shape on the horizontal plane that is consistent from the lower end to the upper end, and is a rectangular prism whose dimension in the thickness direction D1 is longer than that of the protrusion Mb1 of the male mold Mb. That is, the accommodation recess Ma1 is formed so that the recess depth is greater than the protrusion dimension of the protrusion Mb1.

[0050] In the molding die M of this embodiment, the recess depth of the accommodating recess Ma1 of the female die Ma is deeper than the protruding height of the protruding portion Mb1 of the male die Mb, so that even when the protruding portion Mb1 enters the accommodating recess Ma1 and the female die Ma and male die Mb abut at the mold mating surface MP, the tip of the protruding portion Mb1 does not reach the bottom of the accommodating recess Ma1, and a molding space Mv having a rectangular parallelepiped shape (in this embodiment, a "flat rectangular plate shape") is formed inside. That is, in the molding die M of this embodiment, the wall surface of the female die Ma at the bottom of the installation recess Ma1 and the tip end surface (lower end surface) of the protrusion Mb1 form molding surfaces that define the molding space Mv.

[0051] As described above, the molding die M of this embodiment is designed so that the volume of the molding space Mv can be changed by moving the pair of mold members (female die Ma and male die Mb) closer to or farther away from each other.

[0052] In the manufacturing method of the bead foam molded body of this embodiment, such a molding mold M is used, and a first step (step S1-3) of placing a plurality of expanded aromatic polyester resin particles (expanded particles 60') composed of the resin composition in the molding space Mv of the molding mold M and closing the molding mold M is carried out, and a second step (step S4-6) of immersing the molding mold M in hot water and heating the expanded particles (expanded particles 60') placed in the molding space Mv with the hot water until they become fusible, thereby foaming and heat-fusing the expanded particles (expanded particles 60') to each other, is carried out to manufacture the bead foam molded body 100. During heating in the second step, hot water outside the mold M can be introduced into the molding space Mv through the vent holes V of the mold M. This is advantageous in that there are no slit marks on the surface of the foamed molded article and the maximum peak height (Sp) on the surface is small.

[0053] The size of the expanded beads is not particularly limited, and they are usually formed so that the average particle diameter is 0.5 to 10 mm, more preferably 1.0 to 5 mm. The average particle size of the expanded beads means the diameter of a sphere having the same volume as the average volume per expanded bead. The average volume per expanded bead can be determined, for example, as follows.

[0054] (How to calculate the average volume) A sample cup for an air comparison type hydrometer is prepared, and an arbitrary number N (pieces) of about 50 to 100 foamed resin particles are placed in this sample cup. The expanded beads are generally conditioned for 12 hours or more in a space adjusted to 23°C and 65% RH before use. Next, the total volume of the foam particles V (mm 3 ) is measured using an air comparison hydrometer at 1-1 / 2-1 atmospheres. The air comparison hydrometer is calibrated using standard bulbs (large 28.9cc, small 8.5cc). The volumetric air comparison type hydrometer may be, for example, a commercially available product from Tokyo Science Co., Ltd. under the trade name "Air Comparison Type Hydrometer 1000". Then, the average volume of the expanded beads is calculated by the following formula. Average volume of foam particles (mm 3 )=V / N

[0055] The bead foam molded body 100 formed from the expanded beads preferably has an expansion ratio of 2 or more. The expansion ratio is more preferably 2.5 or more, and particularly preferably 3 or more. In order to ensure that the foam molded body exhibits excellent strength, the expansion ratio is preferably 50 or less. The expansion ratio may be 40 or less, 30 or less, or 20 or less.

[0056] The foamed bead molded body 100 made of the expanded beads preferably has a density of 675 g / L or less. The density is more preferably 540 g / L or less, and particularly preferably 450 g / L or less. The density is preferably 27 g / L or more in order to ensure excellent strength of the foamed molded body. The density may be 34 g / L or more, 45 g / L or more, or 68 g / L or more.

[0057] When the expanded beads are placed in the molding space of the mold in the first step, the amount of the placed expanded beads (the volume of the expanded beads including the spaces between the expanded beads (apparent volume)) can be, for example, 0.5 to 3 times the volume of the molding space, and preferably 1 to 2 times. If the amount of the placed expanded beads is more than 1 time the volume of the molding space, the expanded beads will be pressurized when placed. This is advantageous in that there are no slit marks on the surface of the foamed molded article and the maximum peak height (Sp) on the surface is small.

[0058] In the second step, hot water can be introduced into the molding space through vent holes on the side of the mold. The provision of vent holes is advantageous in that it improves the expandability of the expanded beads, improves the surface appearance of the foamed molded article, and increases the rate of dimensional change upon heating. The shape and size of the opening of the vent hole (particularly the opening on the molding space side) may be any shape and size that prevents all or part of the expanded beads contained in the molding space from entering the opening of the vent hole. The vent hole has an opening on the molding space side and an opening on the outside of the mold. The shapes of both openings may be the same or different. The shape of the opening of the vent hole may be, for example, round, elliptical, polygonal (rectangle, pentagon, hexagon, etc.), etc.

[0059] The number of vent holes may be one or more and is not particularly limited. From the viewpoint of efficiently discharging gas from within the molding space, it is preferable that there be more than one vent hole per molding die, and more preferably 2, 4, 8, 12, 16, etc. Furthermore, the number of vent holes per side surface of the molding die may be one or more, and when there are more than one vent hole, it may be 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0060] The vent hole is preferably located on the side of the mold that forms the molding space, closer to the surface opposite the surface being pressurized. For example, when the mold is pressurized from above, the vent hole opening on the side of the mold is preferably located near the bottom of the molding space from the viewpoint of efficient exhaust (FIGS. 3 and 4). The vent hole opening on the side of the mold may be located within a range of 20% or less, 18% or less, 16% or less, 15% or less, 13% or less, 12% or less, 11% or less, or 10% or less of the height of the side of the molding space from the bottom of the molding space (the reference plane for height; height 0), and within a range of 0% or more, 0.0001% or more, 0.001% or more, or 0.01% or more. These upper and lower limits may be appropriately combined to form a numerical range. For example, 0.0001% and 20% may form a range of 0.0001 to 20%. In the case of the mold used in the examples, the height of the side surface of the molding space is 10 mm, and the vent hole opening is located at a height of 1 mm from the bottom surface of the molding space, so the vent hole opening is located in an area within 10% of the height of the side surface of the molding space from the bottom surface of the molding space.

[0061] The area of ​​one side surface that forms the molding space and has a vent hole (area including the vent hole opening) and the area of ​​the opening of the vent hole (total area of ​​the openings of all vent holes when there are multiple vent holes on that side surface) may be 0.5 to 8%, 0.75 to 7%, or 1 to 6% of the area of ​​the side surface.

[0062] As described above, the size of the opening of the vent hole may be any size that prevents all or part of the expanded beads contained in the molding space from entering the opening of the vent hole. The size of the opening of the vent hole is such that, when the diameter of the largest circle that can fit into the opening (also referred to as the "maximum circle diameter") is B (mm), B can be 20 to 55%, 25 to 50%, and preferably 20 to 45% of the average particle diameter (mm) of the expanded beads. The maximum circular diameter B may be, for example, 0.5 to 2.5 mm, and is preferably 0.8 to 1.5 mm.

[0063] In the second step, the expanded beads may be expanded and heat-sealed under pressure by the closed mold, or may be expanded and heat-sealed without pressure. The amount of expanded beads contained in the mold (the volume of the expanded beads (apparent volume) including the spaces between the expanded beads) may be, for example, 0.5 to 3 times the volume of the molding space, and preferably 1 to 2 times. If the amount is more than 1 time the volume of the molding space, the expanded beads will be pressurized when heated. Expanding and heat-sealing the expanded beads under pressure in the second step is advantageous in that there are no slit marks on the surface of the expanded molded article, the maximum peak height (Sp) on the surface is small, and the thermal dimensional change rate of the expanded molded article is large.

[0064] (Composite structural members) The composite structural member of the present invention includes a foam molded article as a core material. For example, the composite structural member of the present invention is formed by laminating a skin material onto the surface of the foam molded article of the present invention.

[0065] In composite structural members, a skin material is primarily used to protect the surface of the foam molded body and to obtain superior properties that cannot be obtained with the foam molded body alone. For example, the use of a skin material can further improve heat resistance and mechanical strength. The skin material may be laminated over the entire surface of the foam molded body, or over only a portion of the surface.

[0066] Examples of the skin material include fiber reinforced materials, metal sheets, resin films, etc. Among these, fiber reinforced materials are preferred.

[0067] The fibers constituting the fiber reinforcement are not particularly limited, and examples thereof include carbon fiber, glass fiber, aramid fiber, boron fiber, and metal fiber. Carbon fiber, glass fiber, and aramid fiber are preferred because of their excellent heat resistance and mechanical strength, and carbon fiber is more preferred. The fiber reinforcement may be impregnated with a thermosetting resin or a thermoplastic resin. In other words, the skin material may be a prepreg.

[0068] The thermosetting resin is not particularly limited, and examples thereof include epoxy resin, unsaturated polyester resin, phenol resin, melamine resin, polyurethane resin, silicone resin, maleimide resin, vinyl ester resin, cyanate ester resin, and resin obtained by prepolymerizing maleimide resin and cyanate ester resin. Epoxy resin or vinyl ester resin is preferred because of its excellent heat resistance, elastic modulus, and chemical resistance. Only one type of thermosetting resin may be used, or two or more types may be used in combination.

[0069] The thermoplastic resin is not particularly limited, and examples thereof include polyolefin resins, polyester resins, thermoplastic epoxy resins, polyamide resins, thermoplastic polyurethane resins, sulfide resins, and acrylic resins. Polyester resins and thermoplastic epoxy resins are preferred because they have excellent adhesion between the skin material and the foam molded article or between the fibers constituting the fiber reinforcement. Only one type of thermoplastic resin may be used, or two or more types may be used in combination.

[0070] The metal sheet is not particularly limited, and examples thereof include aluminum sheet, stainless steel sheet, iron sheet, steel sheet, and titanium sheet. Aluminum sheet is preferred because it is both lightweight and has excellent mechanical strength. Aluminum sheet also includes aluminum alloy sheet containing 50% or more by mass of aluminum.

[0071] The resin film is not particularly limited, and examples thereof include polyolefin-based resin films, polyester-based resin films, acrylic-based resin films, etc. Examples of the polyolefin-based resin films include polyethylene-based resin films, polypropylene-based resin films, etc. Examples of the polyester-based resin films include polyethylene terephthalate films.

[0072] The skin material is preferably laminated and integrated with the foam molded article. The method for laminating a skin material onto the surface of a foam molded body is not particularly limited, and examples thereof include: (1) a method for laminating a skin material onto the surface of a foam molded body using an adhesive; (2) a method for laminating a skin material (preferably a fiber-reinforced material) impregnated with a thermoplastic resin onto the surface of a foam molded body, and laminating the skin material onto the surface of the foam molded body using the thermoplastic resin impregnated in the skin material as a binder; (3) a method for laminating a skin material (preferably a fiber-reinforced material) impregnated with an uncured thermosetting resin onto the surface of a foam molded body, and laminating the skin material onto the surface of the foam molded body using the thermosetting resin impregnated in the skin material as a binder by curing the thermosetting resin; (4) a method for disposing a heated and softened skin material on the surface of a foam molded body, and pressing the skin material onto the surface of the foam molded body to deform the skin material along the surface of the foam molded body as necessary, and laminating the skin material onto the surface of the foam molded body; and (5) other methods generally used in molding fiber-reinforced resin sheets. Examples of such methods include the autoclave method, hand lay-up method, spray-up method, PCM (Prepreg Compression Molding) method, RTM (Resin Transfer Molding) method, VaRTM (Vacuum assisted Resin Transfer Molding) method, etc. The autoclave method, RTM method, and VaRTM method are preferred because they improve the adhesion between the skin material and the foam molded article or between the fibers that make up the fiber reinforcement material.

[0073] In addition to the inherent properties of foamed molded articles, such as light weight, soundproofing, thermal insulation, and vibration damping, composite structural members can be integrated with skin materials to add various functions (heat resistance, abrasion resistance, abrasion resistance, beautiful appearance, chemical resistance, water resistance, oil resistance, stain resistance, etc.). Therefore, in addition to the applications traditionally associated with aromatic polyester resin foamed molded articles, composite structural members can be used in a variety of fields, including construction, transportation equipment (automobiles, motorcycles, buses, trains, aircraft, ships, etc.), space, energy technology (e.g., wind turbine rotors), sports (various exercise equipment, etc.), the electrical industry, and the electronics industry. Examples of such composite structural members include aircraft equipment structures (e.g., helicopter blades), interior and exterior materials for various vehicles, materials for sporting goods, materials for leisure goods, sandwich structural materials, and wind power generator blades. Examples of automotive components include door panels, door liner parts, bumpers, fenders, fender supports, engine covers, roof panels, trunk lids, floor panels, instrument panels, center clusters, center tunnels, and crash boxes. For example, by using composite structural members for door panels that have traditionally been made from steel plates, door panels that have roughly the same rigidity as steel plate door panels can be significantly lighter and have improved thermal insulation and soundproofing properties. [Example]

[0074] Hereinafter, one embodiment of the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto. The methods for determining various physical properties in the examples are described below. The surface of the foamed molded article measured in the examples is the upper surface of the foamed molded article (the surface that contacts the mold lid during production). Therefore, the surface properties of the foamed molded article measured in the examples are the properties of the upper surface of the foamed molded article.

[0075] (Average particle size of expanded particles) The average particle size of the expanded beads was measured by the following method. First, several types of sieves with different mesh sizes specified in JIS (mesh size 6.70 mm, 5.60 mm, 4.75 mm, 4.00 mm, 3.35 mm, 2.80 mm, 2.36 mm, 2.00 mm, 1.70 mm, 1.40 mm, 1.18 mm, 1.00 mm, 0.850 mm, 0.710 mm, 0.600 mm, 0.500 mm) were prepared, and 50 g of expanded particles were sieved through the sieves in the order of largest to smallest mesh sizes. The expanded particles were then unable to pass through sieves with mesh sizes of a predetermined size depending on the particle size of each particle, and remained on each sieve. The average particle size of the expanded particles remaining on each sieve was determined based on the size of the sieve openings, as shown in the following table. For example, the particle size of the expanded particles remaining on a sieve with an opening size of 1.70 mm was determined to be 1.85 mm.

[0076] [Table 1]

[0077] (Bulk density of expanded particles) Approximately 1000cm 3 The expanded particles were placed in a measuring cylinder at 1000 cm 3 Filled to the (1 L) mark. In addition, the measuring cylinder was visually inspected from the horizontal direction, and even one foam particle was found to be within 1000 cm 3 When the scale reached the mark, the filling of the expanded particles into the measuring cylinder was completed at that point. Next, the mass of the expanded particles filled in the measuring cylinder was weighed to two decimal places, and this mass was designated as W (g). Then, the bulk density of the expanded beads was calculated using the following formula. Bulk density (g / L) = W

[0078] (Apparent volume of expanded particles) 1000cm 3A measuring cylinder capable of measuring (1 L) was prepared, and the expanded particles were filled into the measuring cylinder. The measuring cylinder was visually observed from the horizontal direction, and the mark reached by at least one expanded particle was regarded as the apparent volume (cm) of the expanded particles. 3 ) was decided.

[0079] (Density of foamed molded product) The mass (a) and volume (b) of the foamed molded article (which was dried at 25°C for at least 20 hours after molding) were measured to three or more significant figures, and the density (g / L) of the foamed molded article was calculated using the formula (a) / (b).

[0080] (Internal fusion rate of foam molded body) A slit approximately 2 mm deep was made on the top surface of the foamed molded article with a utility knife, and the foamed molded article was then divided into two along the slit to expose the fracture surface. An arbitrary area containing 150 foamed beads was designated on the fracture surface, and the foamed beads within that area were observed. The number of foamed beads broken within the foamed beads (a) and the number of foamed beads broken at the interface between the foamed beads (b) were counted, and the values ​​obtained by substituting these values ​​into the formula [(a) / ((a)+(b))]×100 were used to determine the fusion rate (%). The foamed molded article used to measure the fusion rate was essentially flat, approximately 10 mm thick, 200 mm wide, and 200 mm long, and the slit was made so that it crossed the center of the foamed molded article in the longitudinal direction toward the width direction. If the number of expanded beads observed on the fracture surface is less than 150, all expanded beads on the fracture surface can be observed, and the number of expanded beads that have broken within the expanded beads (a) and the number of expanded beads that have broken at the interface between the expanded beads (b) can be counted and substituted into the above formula to calculate the fusion rate.

[0081] (Maximum peak height (Sp) of the surface of the foamed molded product) The maximum peak height (Sp) on the surface of the foamed molded article was measured using a measuring device (VR-3200 manufactured by Keyence Corporation) in accordance with ISO25178. The details of the measurement method are described below. [sample] The measurement surface of the foam molded article was cut into a size of 5 cm x 6 cm and attached to a flat metal plate with double-sided tape. The measurement surface was the surface with the largest area and the surface that came into contact with the male mold during foam molding, and was the surface that was the target for measuring the maximum peak height (Sp) mentioned above. [Measurement conditions] Magnification: 12x Measurement conditions: Expert Measurement mode: Super fine Measurement direction: both sides Measurement brightness adjustment: Auto (80) Defect point / saturation point display: ON [analysis] The following analysis was performed using the captured images. The analysis was performed using Keyence's analysis application. [Analysis conditions] Image processing: After surface correction across the entire area Filter Settings: No Cutoff End effect correction: Unchecked Surface roughness analysis was carried out over the entire area to determine the maximum peak height (Sp). The measurement was performed three times, and the average value was calculated.

[0082] (DSC measurement) The foamed molded article was thinly sliced ​​with a cutter knife within a 2 mm thick area from the surface to prepare a sample. The sample (5.5 ± 0.5 mg) was packed tightly into the bottom of an aluminum measurement container, and then covered with an aluminum lid. Differential scanning calorimetry was then performed using a Hitachi High-Tech Science DSC7000X, AS-3 differential scanning calorimeter. The sample was heated under a nitrogen gas flow rate of 20 mL / min in the following steps to obtain a DSC curve. Alumina was used as the reference material. (Step 1) Hold at 30°C for 2 minutes. (Step 2) The temperature is increased from 30°C to 290°C at a rate of 10°C / min.

[0083] (crystallization temperature, melting temperature) From the DSC curve obtained in the DSC measurement, the crystallization temperature and melting temperature of the surface of the foamed molded article were determined. Using the analysis software attached to the differential scanning calorimeter, the top temperatures of the crystallization peak and melting peak observed during the temperature rise process were read from the DSC curve and taken as the crystallization temperature and melting temperature (melting point), respectively.

[0084] (crystallinity) The crystallinity was measured by the method described in JIS K7122:1987 and JIS K7122:2012. From the DSC curve obtained in the DSC measurement, the area of ​​the melting peak, the heat of fusion C1 (J / g) calculated from the area of ​​the melting peak, and the area of ​​the crystallization peak, the heat of crystallization C2 (J / g) calculated from this area were determined using the analysis software attached to the differential scanning calorimeter. The heat of crystallization was subtracted from the heat of fusion to determine the difference. The degree of crystallization was determined by dividing this difference by 140.1 J / g, which is the theoretical heat of fusion for perfectly crystalline polyethylene terephthalate. Specifically, the heat of fusion was calculated from the area enclosed by the line connecting the point where the DSC curve departs from the low-temperature baseline and the point where the DSC curve returns to the high-temperature baseline, and the heat of crystallization was calculated from the area enclosed by the line connecting the point where the DSC curve departs from the low-temperature baseline and the point where the DSC curve returns to the high-temperature baseline, and the area enclosed by the line connecting the point where the DSC curve departs from the low-temperature baseline and the point where the DSC curve returns to the high-temperature baseline. That is, the crystallinity was calculated using the following formula: Crystallinity (%)=((C1-C2) / 140.1)×100

[0085] (Heat dimensional change rate) The thermal dimensional change rate of the foamed molded article was measured by Method B described in JIS K 6767:1999 "Foamed plastics - Polyethylene - Testing method." Specifically, the measurement was performed as follows. A test piece measuring 150 mm long x 150 mm wide x 30 mm high was cut out from the foamed molded article. On the surface of the test piece, three 50 mm long straight lines were drawn in the vertical direction, parallel to each other. In addition to markings at intervals of 50 mm, three horizontally oriented straight lines, each 50 mm long, were drawn parallel to each other at intervals of 50 mm. The test piece was then heated in a hot air circulation dryer at 130°C for 168 hours, removed, and left at 25°C for 1 hour. Next, the lengths of the six straight lines drawn on the surface of the test piece were measured, and the arithmetic mean value L1 of the lengths (mm) of the six straight lines was calculated. The degree of change S was calculated using the following formula, which was used as the thermal dimensional change rate. S(%) = 100 × (L1-50) / 50

[0086] Example 1 (1) Preparation of foam particles Expanded beads were produced using the production apparatus shown in FIGS. 5 to 7 according to the following procedure.

[0087] Plant-derived polyethylene terephthalate (intrinsic viscosity: 0.80, density: 1400 kg / m 3 , melting point: 247.2°C, glass transition temperature: 78.7°C, mass average molecular weight: 74,000, plant content: 30%) 95% by mass and polyethylene naphthalate (intrinsic viscosity: 0.50, density: 1330 kg / m 3 An aromatic polyester resin composition was obtained by blending 100 parts by mass of an aromatic polyester resin material containing 5% by mass of polyethylene terephthalate (polyethylene terephthalate content: 60% by mass, talc content: 40% by mass, intrinsic viscosity of polyethylene terephthalate: 0.82), 1.8 parts by mass of a masterbatch obtained by incorporating talc into polyethylene terephthalate (polyethylene terephthalate content: 60% by mass, talc content: 40% by mass, intrinsic viscosity of polyethylene terephthalate: 0.82), and 0.25 parts by mass of pyromellitic anhydride.

[0088] The obtained aromatic polyester resin composition was fed to a single-screw extruder having a bore diameter of 65 mm and an L / D ratio of 35, and melt-kneaded at 290° C. The kneading time was 15 minutes.

[0089] Next, butane (containing 35% by mass of isobutane and 65% by mass of normal butane) was introduced into the extruder as a foaming agent, and the foaming agent was injected into the molten aromatic polyester resin composition, thereby uniformly dispersing the foaming agent in the aromatic polyester resin composition. At this time, the amount of butane added was 1.2 parts by mass per 100 parts by mass of the aromatic polyester resin material.

[0090] Thereafter, the molten aromatic polyester resin composition was cooled to 270°C at the front end of the extruder, and then extrusion foamed from each nozzle of the multi-nozzle mold 1 attached to the front end of the extruder. The extrusion rate of the aromatic polyester resin composition was set to 38 kg / hour.

[0091] The multi-nozzle mold 1 had 50 nozzles, each with an outlet 11 diameter of 0.8 mm, and all of the nozzle outlets 11 were arranged at equal intervals on an imaginary circle A with a diameter of 139.5 mm, which was assumed to be on the front end face 1a of the multi-nozzle mold 1.

[0092] Two rotary blades 5 were integrally provided on the outer peripheral surface of the rear end of the rotary shaft 2, with a phase difference of 180° in the circumferential direction of the rotary shaft 2. Each rotary blade 5 was configured to move on an imaginary circle A while constantly contacting the front end surface 1a of the multi-nozzle mold 1. The rotary shaft 2 passed through the front part 41a of a cooling drum 41 constituting the cooling member 4, and was connected to a driving member 3 which was a motor.

[0093] The cooling member 4 includes a cooling drum 41. The cooling drum 41 has a front portion 41a that is circular at the front and a cylindrical peripheral wall portion 41b that extends rearward from the outer periphery of the front portion 41a and has an inner diameter of 320 mm. Cooling water 42 at 30°C was supplied into the cooling drum 41 through a supply pipe 41d and a supply port 41c of the cooling drum 41. The internal volume of the cooling drum 41 was 17,684 cm. 3 It was.

[0094] The cooling water 42 flows forward in a spiral along the inner circumferential surface of the circumferential wall 41b of the cooling drum 41 due to centrifugal force generated by the flow rate when the cooling water 42 is supplied from the supply pipe 41d to the inner circumferential surface of the circumferential wall 41b of the cooling drum 41. As the cooling water 42 flows along the inner circumferential surface of the circumferential wall 41b, the cooling water 42 gradually spreads in a direction perpendicular to the direction of its movement. As a result, the inner circumferential surface of the circumferential wall 41b forward of the supply port 41c of the cooling drum 41 is entirely covered with the cooling water 42. In FIG. 7, the cooling water 42 flows in the direction indicated by the arrow X.

[0095] The rotary blade 5 disposed on the front end face 1a of the multi-nozzle mold 1 was rotated at a rotation speed of 2500 rpm, and the extrudate (extruded foam) of the aromatic polyester resin extruded and foamed from the outlet 11 of each nozzle of the multi-nozzle mold 1 was cut by the rotary blade 5 to produce approximately spherical particulate cut products.

[0096] The extrudate of the aromatic polyester resin consisted of an unfoamed portion immediately after being extruded from the nozzle of the multi-nozzle mold 1 and a foamed portion in the process of foaming that was continuous with the unfoamed portion. The extrudate of the aromatic polyester resin was cut at the open end of the outlet 11 of the nozzle, and the cutting of the extrudate of the aromatic polyester resin took place in the unfoamed portion.

[0097] When producing the expanded beads, first, the rotating shaft 2 was not attached to the multi-nozzle mold 1, and the cooling member 4 was retracted from the multi-nozzle mold 1. In this state, an aromatic polyester resin extrudate was extruded and foamed from the extruder, and it was confirmed that the aromatic polyester resin extrudate consisted of an unfoamed portion immediately after being extruded from the nozzle of the multi-nozzle mold 1 and a foamed portion in the process of foaming that was continuous with the unfoamed portion. After this confirmation, the rotating shaft 2 was attached to the multi-nozzle mold 1, the cooling member 4 was placed in a predetermined position, and then the rotating shaft 2 was rotated. The aromatic polyester resin extrudate was cut with the rotary blade 5 at the open end of the nozzle outlet 11 to produce granular cut pieces.

[0098] The resulting particulate cutting material was thrown outward or forward by the cutting stress of the rotary blade 5. The thrown particulate cutting material collided obliquely with the surface of cooling water 42 flowing along the inner surface of the cooling drum 41 of the cooling member 4, from the upstream side to the downstream side of the flow of cooling water 42, so as to follow the cooling water 42, and the particulate cutting material entered the cooling water 42 and was immediately cooled.

[0099] The particulate cut material was discharged together with cooling water 42 through the discharge port 41e of the cooling drum 41, and then separated from the cooling water 42 in a dehydrator. In this manner, expanded beads (expanded aromatic polyester resin beads) were produced.

[0100] (2) Preparation of foam molded body A foamed molded article was produced by the following procedure.

[0101] A straight plate-shaped molding space Mv (volume Vmin: 400cm) measuring 200mm long x 200mm wide x 10mm deep 3 Foam molding was performed using a mold M (Figs. 3 and 4) equipped with a mold chamber (Fig. 3) and having vent holes V (height 1 mm, length 100 mm) in its side walls. One vent hole V was provided on each side wall of the mold M, allowing hot water outside the mold to be introduced into the molding space Mv. The mold was filled with 56 g of the expanded beads (average particle diameter 2.5 mm; bulk density 150 g / L) produced above. The amount of the expanded beads filled was equal to the volume of the molding space Mv. The mold was closed and the bolts (not shown) installed at the four corners of the mold were tightened to close the mold. 100 liters of hot water at 90°C was placed in a container capable of maintaining the temperature of hot water. The mold was entirely immersed in this hot water. 10 minutes after the start of immersion, the mold was removed from the container containing the hot water. After removing the mold, 50 liters of water at 25°C was placed in the container and the mold was entirely immersed in this water to cool. 20 minutes after the start of immersion, the mold was removed from the container containing the water. The mold was then opened and the foam molded article was removed.

[0102] Examples 2 to 5, Reference Examples 1 to 6 A foam-molded article was obtained in the same manner as in Example 1, except that in the foam-molded article production step, the hot water temperature (° C.) and immersion time (minutes) were changed to the values ​​shown in Table 2.

[0103] The foamed molded articles obtained in Examples 1 to 5 and Reference Examples 1 to 6 were subjected to various tests. The outlines of Examples 1 to 5 and Reference Examples 1 to 6 and the test results are shown in Table 2. No slit marks were observed on the surfaces of the foamed molded articles obtained by immersion treatment in hot water.

[0104] [Table 2]

[0105] The thermal dimensional change rates of the foamed molded articles of Examples 1 to 5 all exceeded 1%. The foamed molded articles of Examples 1 to 5 had small maximum peak heights (Sp) on their surfaces.

[0106] Comparative Example 1 A foamed molded article was obtained in the same manner as in Example 1, except that in the foamed molded article preparation step, the foamed molded article was obtained by the steam heating method described below.

[0107] (2) Preparation of foam molded body A foamed molded article was produced by the following procedure.

[0108] An in-mold foam molding machine was prepared, equipped with a mold including a male mold and a female mold. When the male mold and the female mold were clamped together, a rectangular parallelepiped molding space with interior dimensions of 200 mm length x 200 mm width x 10 mm height was formed between the male and female molds.

[0109] The mold had a total of 252 circular supply ports, each 8 mm in diameter, spaced 20 mm apart to supply steam for heating from outside the mold through the mold to the expanded beads in the molding space. Each supply port had a lattice section (slits; lattice width 1 mm) on its entire surface, preventing the expanded beads filled in the mold from leaking out of the mold through the supply port. The mold was also configured to allow steam to be smoothly supplied from outside the mold into the molding space through the supply ports.

[0110] The foamed beads were filled into the molding space of the mold in the same manner as in Example 1. Steam at 120°C was supplied into the molding space for 60 minutes to heat and expand the foamed beads, and the secondary foamed beads were integrated by thermal fusion. Next, cooling water was supplied into the molding space to cool the foamed molded body in the molding space for 2 minutes, and then the mold was opened and the foamed molded body was removed.

[0111] The resulting foamed molded article had a density of 150 g / L, an internal fusion rate of 84%, a melting temperature of 244.1°C, no crystallization temperature, and a crystallinity of 24.8%. Although the foamed molded article had a maximum peak height (Sp) of 0.35 mm, slit marks corresponding to the shape of the steam supply port were observed on the surface, and the dimensional change upon heating to 130°C was small at 0.25%. [Explanation of symbols]

[0112] E1: long side, E2: short side, F1: area from the long side to a length equivalent to 10% of the average length of the long and short sides (the sum of the long and short side lengths divided by 2), F2: area from the short side to a length equivalent to 10% of the average length of the long and short sides, F3: area excluding the area corresponding to the end of the plan view, f1: area corresponding to the plan view area F1, f2: area corresponding to the plan view area F2, f3: surface of the foamed molded article corresponding to the plan view area F3 1: multi-nozzle mold, 1a: front end surface, 2: rotary shaft, 3: driving member, 4: cooling member, 5: rotary blade, 11: outlet portion, 41: cooling drum, 41a: front portion, 41b: peripheral wall portion, 41c: supply port, 41d: supply pipe, 41e: discharge port, 42: cooling water 60': Expanded particles (expanded particles before fusion; pre-expanded particles), 60: Expanded particles (after fusion), 100: Bead expansion molding, D1: Thickness direction (opening and closing direction of the molding die), M: Molding die, Ma: Female die, Mb: Male die, Mv: Molding space

Claims

1. An aromatic polyester resin foam molded article for use as a core material of a composite structural member, The foamed molded body contains 90% by mass or more of polyethylene terephthalate, the foamed molded article has a surface crystallinity of 3 to 20% as measured by a differential scanning calorimeter (DSC); the foamed molded body has a thermal dimensional change rate of 1 to 10% after being left to stand in a thermostatic bath at 130°C for 168 hours; Foam molding.

2. The foam molded article according to claim 1, wherein the maximum peak height (Sp) of the surface of the foam molded article is 0.70 mm or less.

3. 2. The foamed molded article according to claim 1, wherein the fusion rate of the foamed particles constituting the foamed molded article is 0 to 10%.

4. A composite structural member comprising the foam molded article according to any one of claims 1 to 3 as a core material.

5. A method for producing a foam molded article, comprising the steps of: producing an aromatic polyester resin foam molded article using a mold having a molding space for molding the foam molded article; a first step of placing foamed aromatic polyester resin particles in the molding space of the mold and closing the mold; and a second step in which the closed mold is immersed in hot water at 90 to 100°C to introduce the hot water into the mold, thereby expanding and heat-sealing the foamed particles contained in the mold, thereby forming the foamed molded article; Including, the mold has a vent hole on a side surface thereof that communicates with the molding space; The immersion treatment is carried out for an immersion time such that the value calculated by multiplying the hot water temperature (°C) by the immersion time (minutes) is 600 to 3000 when the hot water temperature is 90°C or higher but lower than 95°C, and such that the value calculated by multiplying the hot water temperature (°C) by the immersion time (minutes) is 400 to 950 when the hot water temperature is 95 to 100°C, The foamed molded body contains 90% by mass or more of polyethylene terephthalate, the foamed molded article has a surface crystallinity of 3 to 20% as measured by a differential scanning calorimeter (DSC); the foamed molded body has a thermal dimensional change rate of 1 to 10% after being left to stand in a thermostatic bath at 130°C for 168 hours; A method for producing a foamed molded article.

6. The method for producing a foam molded article according to claim 5, wherein the foam molded article has a maximum peak height (Sp) of 0.70 mm or less on the surface thereof.

7. The method for producing a foamed molded article according to claim 5 or 6, wherein the fusion rate of the foamed beads constituting the foamed molded article is 0 to 10%.

Images