Feeder for bead filling, mold for molding foamed bead body, foamed bead body, and method for producing foamed bead body

Abstract

The present invention makes it possible to produce a foamed bead body with no defects and an adequate shape when producing a foamed bead body, particularly when producing a foamed bead body that is a thin-walled molded article. The present invention is a feeder for bead filling wherein the plunger tube length of a tip part of the feeder is 10-40 mm and the angle of inclination of an inclined flow path in the tip part of the feeder is 10 degrees or more and less than 30 degrees.

Description

Feeder for filling beads, mold for molding foamed beads, foamed beads, and method for manufacturing foamed beads

[0001] The present invention relates to a feeder for filling beads, a mold for molding a bead foam, a bead foam, and a method for producing a bead foam.

[0002] Resin bead foams, which are molded articles made from resin foam beads as a raw material, are expected to have a wide range of applicability as molded articles having properties such as flame retardancy, heat resistance, insulation, and high dimensional accuracy depending on the properties of the resin. For example, Patent Documents 1 and 2 describe feeders used to blow resin foam beads into a mold when molding an article made from resin foam beads as a raw material. Patent Documents 3 to 5 propose molds that can be used to mold an article made from resin foam beads as a raw material.

[0003] Resin bead foams can be used for a variety of applications, but demand for thin-walled molded products of resin bead foams is particularly growing for automotive and wireless communication applications, etc. When resin foam beads, the raw material, are blown into a mold with a feeder and molded in the mold, localized filling defects tend to occur, and particularly when molding thin-walled molded products, the area near the feeder is prone to defects (holes), making it difficult to obtain thin-walled molded products with shapes sufficient for automotive and wireless communication applications, etc.

[0004] Japanese Patent Application Laid-Open No. 2001-001359 Japanese Patent Application Laid-Open No. 2011-104784 Japanese Patent Application Laid-Open No. 07-178749 Japanese Patent Application Laid-Open No. 11-020027 Japanese Patent Application Laid-Open No. 2001-198940

[0005] The present invention has been made in consideration of the above circumstances, and aims to provide a feeder used to fill raw beads into a mold for molding a bead foam (for example, a bead foam that is a thin-walled molded product) that has a satisfactory shape without defects, particularly one that does not have any voids in the area near the feeder of the mold, a mold for molding such a bead foam, a bead foam molded using such a mold, and a method for manufacturing such a bead foam.

[0006] As a result of intensive research to solve the above-mentioned problems, the inventors have discovered that, when producing a bead foam using a mold equipped with multiple feeders, by using feeders in which the plunger tube length at the tip portion of the feeder is 10 mm or more and 40 mm or less, and the inclination angle of the inclined flow path at the tip portion of the feeder is 10 degrees or more and less than 30 degrees, it is possible to produce a bead foam having a satisfactory shape without defects in the production of bead foam, particularly a bead foam that is a thin-walled molded product; and that by molding a bead foam using a mold in which the molding material filling space of the mold has a pair of opposing surfaces, one of the pair of surfaces having a feeder and the other surface having a core vent, and in which the area in one surface where at least one feeder is present and the area in the other surface where at least one core vent is present overlap in a view perpendicular to the opposing surface, it is possible to produce a bead foam that is a thin-walled molded product having a satisfactory shape without defects, thereby completing the present invention.

[0007] That is, the present invention is as follows. [1] A feeder for filling beads, wherein the plunger tube length at the tip of the feeder is 10 mm or more and 40 mm or less, and the inclination angle of the inclined flow path at the tip of the feeder is 10 degrees or more and less than 30 degrees. [2] The feeder for filling beads according to [1], wherein the intersection distance of the inclined flow path at the tip of the feeder is 0 mm or more and 20 mm or less. [3] The feeder for filling beads according to [1] or [2], wherein the tip of the feeder has a slit. [4] A bead foam containing a resin, wherein the bead foam has one or more portions corresponding to feeder discharge marks during bead foam molding, and the thinnest thickness of the portions corresponding to the feeder discharge marks is 5 mm or less. [5] The bead foam according to [4], wherein the thickness of a part of the bead foam is 60 mm or less. [5a] A bead foam containing a resin, the bead foam having one or more portions corresponding to feeder discharge outlets during bead foam molding, the thickness of a molding material filling space where at least one of the feeder discharge outlets is present is 5 mm or less, and the thickness of a portion of the molding material filling space is 2 mm or more and 60 mm or less. [6] The bead foam according to any of [4] to [5a], having a pair of opposing surfaces, one of the pair of surfaces having a portion corresponding to a feeder discharge mark during bead foam molding, and the other surface having a portion corresponding to a core vent mark during bead foam molding, and in a view perpendicular to the one surface, part or all of the portion of the other surface corresponding to at least one core vent mark is present within the area occupied by the feeder discharge mark. [6a] A bead foam containing a resin, the bead foam having one or more portions corresponding to the outlet of a feeder used in molding the bead foam, and at least one of the portions corresponding to the outlet of the feeder having a minimum thickness of 5.0 mm or less.[6b] The bead foam according to [6a], having a pair of opposing surfaces, one of which has one or more portions corresponding to feeder outlets during bead foam molding, and the other surface has portions corresponding to core vents during bead foam molding, and in a view perpendicular to the one surface, part or all of at least one core vent on the other surface is present within an area occupied by at least one of the portions corresponding to the feeder outlets. [7] The bead foam according to any of [4] to [6b], having a runner portion that is cut off during use, the runner portion having a portion that corresponds to a feeder discharge mark during bead foam molding. [7a] The bead foam according to any of [4] to [7], having a runner portion that is cut off during use, the runner portion having at least one portion that corresponds to a feeder outlet during bead foam molding. [8] The bead foam according to [7] or [7a], characterized by the following (A) or (B): (A) The runner portion exists in a direction perpendicular to the plane of the bead foam; (B) The runner portion exists within the plane of the bead foam [8a] The bead foam according to [8], wherein the runner portion exists in a direction perpendicular to the plane of the bead foam. [8b] The bead foam according to [8], wherein the runner portion exists within the plane of the bead foam. [9] The bead foam according to any of [4] to [8b], which has an air vent mark on a feeder discharge mark during bead foam molding. [9a] The bead foam according to any of [4] to [9], which has a slit mark around at least one portion corresponding to the feeder discharge port during bead foam molding.

[10] The flattening ratio of the foamed beads at the portion corresponding to the feeder discharge mark during bead foam molding (1 cm of the cross section of the foamed beads at the portion corresponding to the feeder discharge mark. ２The bead foam according to any one of [4] to [9a], wherein the average value of ((maximum in-plane diameter - maximum thickness direction diameter) / maximum in-plane diameter)) is 0.7 or less per 1 cm of the cross section of the foamed beads in at least one portion corresponding to the outlet of the feeder during the molding of the bead foam. ２

[11] The bead foam according to any one of [4] to

[10] , wherein the average value of ((maximum in-plane diameter - maximum thickness direction diameter) / maximum in-plane diameter)) is 0.7 or less per 1 cm of the cross section of the bead foam at the part corresponding to the feeder discharge mark. ２ The bead foam according to [4] or [5], wherein the number of expanded beads in the thickness direction in the bead foam (average number of expanded beads in the thickness direction per 1 cm of the cross section of the bead foam corresponding to the feeder outlet) is 1.2 or more and 15 or less. [11a] In at least one portion corresponding to the outlet of the feeder, the number of expanded beads in the thickness direction in the bead foam (average number of expanded beads in the thickness direction per 1 cm of the cross section of the bead foam corresponding to the feeder outlet) is 1.2 or more and 15 or less. ２The bead foam according to any one of [4] to

[11] , wherein the average number of foamed beads in the thickness direction per bead foam (average number of foamed beads in the thickness direction per bead foam) is 1.2 or more and 15 or less.

[12] The bead foam according to any one of [4] to [11a], wherein the ratio of the density of a portion corresponding to a feeder discharge port mark during bead foam molding to the average density of the entire bead foam molding is 110 to 300%.

[13] The bead foam according to any one of [4] to [11a], wherein the ratio of the modulus of elasticity of a portion corresponding to a feeder discharge port mark during bead foam molding to the average modulus of elasticity of the entire bead foam molding is 120 to 600%. [13a] The bead foam according to any one of [4] to

[13] , wherein there is a slit mark around at least one portion corresponding to a feeder discharge port during bead foam molding.

[14] A bead foam molding mold characterized by the following (A) or (B):(A) The molding material filling space of the mold has a pair of opposing surfaces, the molding material filling space is connected to a feeder, one of the pair of surfaces has a discharge outlet of the feeder, and the other surface has a core vent, the thickness of the molding material filling space at the part where the discharge outlet of the feeder is present is 5 mm or less, and in a view perpendicular to the one surface, part or all of at least one core vent in the other surface is present within the area occupied by the discharge outlet of the feeder; (B) The molding material filling space of the mold has a part corresponding to a runner part that is cut off when a bead foam molded with the mold is used, the part corresponding to the runner part has feeder discharge marks, and the thickness of the molding material filling space at the part where the discharge outlet of the feeder is present is 5 mm or less [14a] The molding material filling space of the mold has a pair of opposing surfaces, the molding material filling space is connected to one or more feeders, one of the pair of surfaces has discharge outlets of the feeder in one or more places, A mold for molding a bead foam, wherein the other surface has a core vent, the thickness of the molding material filling space in the portion where at least one of the feeder discharge ports is present is 5 mm or less, and part or all of at least one core vent in the other surface is present within the area occupied by at least one of the feeder discharge ports in a view perpendicular to the one surface. [14b] A mold for molding a bead foam, wherein the molding material filling space of the mold has a portion corresponding to a runner portion that will be cut off when the bead foam molded with the mold is used, and the portion corresponding to the runner portion has at least one of the feeder discharge ports, and the thickness of the molding material filling space in the portion where at least one of the feeder discharge ports is present is 5 mm or less.

[15] A mold for molding a bead foam, wherein the molding material filling space of the mold has a pair of opposing surfaces, the molding material filling space is connected to one or more feeders, one of the pair of surfaces has one or more outlets for the feeders, and one or more of the feeders is the feeder described in any one of [1] to [3].[15a] A mold for molding a bead foam, wherein the molding material filling space of the mold has a pair of opposing surfaces, the molding material filling space is connected to a plurality of feeders, one of the pair of surfaces has outlets for the feeders at a plurality of locations, and one or more of the feeders is the feeder described in any one of [1] to [3]. [15b] A mold for molding a bead foam, wherein the molding material filling space of the mold has a pair of opposing surfaces, the molding material filling space is connected to a plurality of feeders, one of the pair of surfaces has outlets for the feeders at a plurality of locations, the thickness of the molding material filling space at a portion where at least one of the feeder outlets is present is 5 mm or less, and the thickness of a portion of the molding material filling space is 2 mm or more and 60 mm or less.

[16] A mold for molding a bead foam according to any one of

[14] to [15b], which has a vent near the outlet of the feeder. [16a] A mold for molding a bead foam according to any one of

[14] to

[16] , wherein a slit hole is present near at least one of the discharge ports of the feeders.

[17] A method for producing a bead foam, comprising the steps of: filling a molding material filling space of the mold with thermoplastic resin beads via one or more feeders; and performing bead expansion molding on the thermoplastic resin beads filled in the molding material filling space of the mold to form a bead foam, characterized by the following (A) or (B):(A) The molding material filling space of the mold has a pair of opposing surfaces, one of which has the feeder discharge outlet and the other has a core vent, the thickness of the molding material filling space where the feeder discharge outlet is present is 5 mm or less, and in a view perpendicular to the one surface, part or all of at least one core vent in the other surface is present within the area occupied by the feeder discharge outlet; (B) The molding material filling space of the mold has a portion corresponding to a runner portion that is cut off when a bead foam molded by the mold is used, and the portion corresponding to the runner portion has the feeder discharge outlet, and the thickness of the molding material filling space where the feeder discharge outlet is present is 5 mm or less

[18] The method comprises the following steps: a step of filling thermoplastic resin beads into the molding material filling space of the mold via one or more feeders; and a step of performing bead expansion molding on the thermoplastic resin beads filled in the molding material filling space of the mold to form a bead foam, wherein the molding material filling space of the mold has a pair of opposing surfaces, a bead foam manufacturing method comprising the following steps: filling the molding material filling space of the mold with thermoplastic resin beads via one or more feeders; and performing bead expansion molding on the thermoplastic resin beads filled in the molding material filling space of the mold to form a bead foam, wherein the molding material filling space of the mold has a pair of opposing surfaces, one of the pair of surfaces has one or more discharge ports of the feeder, and the other surface has a core vent, the thickness of the molding material filling space where at least one of the discharge ports of the feeder is present is 5 mm or less, and when viewed perpendicular to the one surface, an opening of the core vent and at least one of the discharge ports of the feeder have an area where they overlap when viewed perpendicular to the opposing surface.[18b] A method for producing a bead foam, comprising the following steps: filling a molding material filling space of a mold with thermoplastic resin beads via one or more feeders; and performing bead expansion molding on the thermoplastic resin beads filled in the molding material filling space of the mold to form a bead foam, wherein the molding material filling space of the mold has a portion corresponding to a runner portion that will be cut off when the bead foam molded by the mold is used, the portion corresponding to the runner portion has at least one discharge outlet of the feeder, and the thickness of at least one molding material filling space at the portion where the feeder discharge outlet is present is 5 mm or less.

[19] A method for producing a bead foam according to any of

[17] to [18b], having a vent hole near the discharge outlet of the feeder. [19a] A method for producing a bead foam according to any of

[17] to

[19] , having a slit hole near at least one discharge outlet of the feeder.

[0008] According to the present invention, in the production of bead foams, particularly bead foams that are thin-walled molded products, it is possible to produce bead foams that are free of defects and have a satisfactory shape. In particular, the bead foams that are thin-walled molded products produced in this manner are suitable for use in automobiles, wireless communication, and the like.

[0009] An example of a schematic diagram of the feeder (1) of the present invention is shown. An example of a schematic diagram around the tip portion (2) of the feeder (1) of the present invention is shown. An example of a schematic diagram when the feeder (1) of the present invention is in use is shown. An example of a schematic diagram of the feeder (1) of the present invention when it has a vent hole (slit) (2c) is shown. An example of a schematic diagram of the mold (200) of the present invention is shown. It is an example of a cross-sectional view of the mold for forming a bead foam of the present invention. It is a front view of the inner surface of the mold of the feeder-side mold of the mold for forming a bead foam of the present invention. It is a front view of the inner surface of the mold of the opposing-side mold of the mold for forming a bead foam of the present invention. It is a perspective view of the surface on the feeder side of the bead foam of the present invention. It is a perspective view of the surface on the opposing side of the bead foam of the present invention. It is an example of a perspective view from a viewpoint above the back surface of the feeder used in the mold for forming a bead foam of the present invention. It is an example of a perspective view from a viewpoint above the front surface of the feeder of FIG. 9A. It is an example of a top view of the feeder of FIG. 9A. It is an example of a side view of the feeder of FIG. 9A. It is an example of a bottom view of the feeder of FIG. 9A. It is an example of a rear view of the feeder of FIG. 9A. It is an example of a front view of the feeder of FIG. 9A. It is an example of a perspective view from a viewpoint below the back surface of the feeder of FIG. 9A. It is an example of a perspective view from a viewpoint below the front surface of the feeder of FIG. 9A. It is an example of a perspective view from a viewpoint above the back surface of the feeder (with a vent hole (slit) at the discharge port) used in the mold for forming a bead foam of the present invention. It is an example of a perspective view from a viewpoint above the front surface of the feeder of FIG. 10A. It is an example of a top view of the feeder of FIG. 10A. It is an example of a side view of the feeder of FIG. 10A. It is an example of a bottom view of the feeder of FIG. 10A. It is an example of a rear view of the feeder of FIG. 10A. It is an example of a front view of the feeder of FIG. 10A. It is an example of a perspective view from a viewpoint below the back surface of the feeder of FIG. 10A. It is an example of a perspective view from a viewpoint below the front surface of the feeder of FIG. 10A. It is an example of an upper perspective view of the core vent used in the mold for forming a bead foam of the present invention. It is an example of a top view of the core vent of FIG. 11A. It is an example of a side view of the core vent of FIG. 11A. It is an example of a side view of the core vent of FIG. 11A from a viewpoint different from that of FIG. 11C. It is an example of a bottom view of the core vent of FIG. 11A. It is an example of a lower perspective view of the core vent of FIG. 11A. It is a front view of the inner surface of the mold of the feeder-side mold of the mold for forming a bead foam having a runner portion.FIG. 1 is a front view of the inner surface of the opposing mold of a mold for molding a bead foam having a runner portion. FIG. 2 is a perspective view of the feeder side surface of a bead foam having a runner portion. FIG. 3 is a perspective view of the opposing side surface of a bead foam having a runner portion. FIG. 4 is a view of a bead foam having a runner portion with the runner portion separated from the bead foam. FIG. 5 is a front perspective view of the mold used in Example 21. FIG. 6 is a rear perspective view of the mold used in Example 21. FIG. 7 is a diagram showing the front shape of the mold used in Example 21. FIG. 8 is a diagram showing the cross-sectional shape of the mold used in Example 21. FIG. 9 is a front perspective view of the mold used in Example 22. FIG. 10 is a rear perspective view of the mold used in Example 22. FIG. 11 is a diagram showing the front shape of the mold used in Example 22. FIG. 12 is a diagram showing the cross-sectional shape of the mold used in Example 22. FIG. 13 is a front perspective view of the mold used in Example 23. FIG. 14 is a rear perspective view of the mold used in Example 23. FIG. 15 is a diagram showing the front shape of the mold used in Example 23. FIG. 16 is a diagram showing the cross-sectional shape of the mold used in Example 23. FIG. 17 is a front perspective view of the mold used in Example 24. FIG. 18 is a rear perspective view of the mold used in Example 24. FIG. 1 is a diagram showing the front shape of a mold used in Example 24. FIG. 2 is a diagram showing the cross-sectional shape of a mold used in Example 24. FIG. 3 is a front perspective view of a mold used in Example 25. FIG. 4 is a rear perspective view of a mold used in Example 25. FIG. 5 is a diagram showing the front shape of a mold used in Example 25. FIG. 6 is a diagram showing the cross-sectional shape of a mold used in Example 25. FIG. 7 is a front perspective view of a mold used in Example 26. FIG. 8 is a rear perspective view of a mold used in Example 26. FIG. 9 is a diagram showing the front shape of a mold used in Example 26. FIG. 10 is a diagram showing the cross-sectional shape of a mold used in Example 26. FIG. 11 is a front perspective view of a mold used in Example 27. FIG. 12 is a rear perspective view of a mold used in Example 27. FIG. 13 is a diagram showing the front shape of a mold used in Example 27. FIG. 14 is a front perspective view of a mold used in Example 28. FIG. 15 is a rear perspective view of a mold used in Example 28. FIG. 16 is a diagram showing the front shape of a mold used in Example 28. FIG. 10 is a front perspective view of a mold used in Example 29. FIG. 11 is a rear perspective view of a mold used in Example 29. FIG. 12 is a diagram showing the front shape of a mold used in Example 29. FIG. 13 is a diagram showing the cross-sectional shape of a mold used in Example 29. FIG. 14 is a front perspective view of a mold used in Example 30.FIG. 1 is a rear perspective view of the mold used in Example 30. FIG. 2 is a diagram showing the front shape of the mold used in Example 30. FIG. 3 is a diagram showing the cross-sectional shape of the mold used in Example 30. FIG. 4 is a front perspective view of the mold used in Example 31. FIG. 5 is a rear perspective view of the mold used in Example 31. FIG. 6 is a diagram showing the front shape of the mold used in Example 31. FIG. 7 is a diagram showing the cross-sectional shape of the mold used in Example 31. FIG. 8 is a front perspective view of the mold used in Example 32. FIG. 9 is a rear perspective view of the mold used in Example 32. FIG. 10 is a diagram showing the front shape of the mold used in Example 32. FIG. 11 is a diagram showing the cross-sectional shape of the mold used in Example 32. FIG. 12 is a front perspective view of the mold used in Example 33. FIG. 13 is a rear perspective view of the mold used in Example 33. FIG. 14 is a diagram showing the front shape of the mold used in Example 33. FIG. 15 is a front perspective view of the mold used in Example 34. FIG. 16 is a rear perspective view of the mold used in Example 34. FIG. 17 is a diagram showing the front shape of the mold used in Example 34. FIG. 1 is a diagram showing the cross-sectional shape of the mold used in Example 34. FIG. 2 is a front perspective view of the mold used in Example 35. FIG. 3 is a rear perspective view of the mold used in Example 35. FIG. 4 is a diagram showing the front shape of the mold used in Example 35. FIG. 5 is a diagram showing the cross-sectional shape of the mold used in Example 35. FIG. 6 is a front perspective view of the mold used in Comparative Examples 5 and 6. FIG. 7 is a rear perspective view of the mold used in Comparative Examples 5 and 6. FIG. 8 is a diagram showing the front shape of the mold used in Comparative Examples 5 and 6. FIG. 9 is a diagram showing the cross-sectional shape of the mold used in Comparative Examples 5 and 6. FIG. 10 is a diagram showing the opening of the core vent used in the Examples and Comparative Examples. FIG. 11 is a photograph of a bead foam according to the present invention. FIG. 12 is a photograph of a bead foam not according to the present invention.

[0010] (Definitions) The terms used in this specification are defined below.

[0011] <Bead foam and each part of the bead foam> <<Bead foam, expanded beads>> In this specification, the term "bead foam" refers to a molded body formed by aggregating expanded beads. In this specification, the term "expanded beads" refers to a raw material for forming the bead foam, which is a porous bead-like (particulate) object produced by expansion.

[0012] <<Runner portion, main body portion>> In this specification, the "runner portion" refers to the portion of the bead foam that is cut off as an unnecessary part during use. Furthermore, if the bead foam has a runner portion, the portion of the bead foam other than the runner portion is referred to as the "main body portion."

[0013] <Parts of the Mold> <<Molding Material Filling Space>> In this specification, the term "molding material filling space" refers to a void space in the mold that is filled with molding material (expanded beads) to form a molded body.

[0014] <<Core Vent>> In this specification, the term "core vent" refers to a filler for a hole provided on the wall surface of a void space to allow steam or air to pass through.

[0015] <<Feeder, Vent Hole>> <Parts of the Feeder> In this specification, the term "feeder" refers to a transfer pipe for introducing foamed beads into the molding material filling space. The feeder may have an "air vent" (e.g., a slit) near the discharge port. The air vent (e.g., a slit) is a hole for allowing excess air to escape from the molding material filling space into the chamber and / or for allowing air, steam, etc. to flow in and out of the molding material filling space.

[0016] (Contents of the present invention) The contents of the present invention will be described in detail below, partly with reference to the drawings. Note that the drawings are examples for explaining the present invention, and the technical scope of the present invention is not limited by the examples shown in the drawings.

[0017] (Feeder for filling beads) The feeder for filling beads of the present invention is a feeder for filling beads, in which the plunger tube length at the tip portion of the feeder is 10 mm or more and 40 mm or less, and the inclination angle of the inclined portion at the tip portion of the feeder is 10 degrees or more and less than 30 degrees.

[0018] <Feeder Structure> Fig. 1 shows an example of a schematic diagram of the feeder (1) of the present invention. Fig. 2 shows an example of a schematic diagram of the periphery of the tip portion (2) of the feeder (1) of the present invention. Fig. 3 shows an example of a schematic diagram of the feeder (1) of the present invention when in use. Note that Figs. 1 and 2 show schematic diagrams of a single-tube nozzle type feeder as an example of the feeder (1) of the present invention, but even when the feeder (1) of the present invention is a focus type feeder, the periphery of the tip portion (2) has a similar structure.

[0019] The feeder (1) of the present invention comprises at least a main pipe portion (3) and a tip portion (2) (sometimes referred to as a "front pipe"). The feeder (1) of the present invention may optionally further comprise a branch pipe (4) branching from the main pipe portion (3), a plunger (5), and a rod (6) connected to the plunger (5).

[0020] The main pipe portion (3) includes a pipe for transporting the foamed beads on an airflow. The tip portion (2) is a portion for discharging the foamed beads transported from the main pipe portion (3) through an outlet. The tip portion (2) has a region (hereinafter referred to as the "inclined portion (2a)") in which the flow path slopes so that the inner diameter continuously decreases from the connection with the main pipe portion (3) toward the outlet. The tip portion (2) also has a region from the outlet-side end of the inclined portion (2a) to the outlet (the region where the plunger (5) is positioned when the plunger (5) moves toward the outlet; hereinafter referred to as the "plunger tube region"). The length from the outlet-side end of the inclined portion (2a) to the outlet is referred to as the "plunger tube length (L)." In the feeder (1) of the present invention, the extrapolated intersection point of the inclined flow path from the inclined portion (2a) to the inclined flow path is referred to as the "intersection point (2b)." The "intersection point (2b)" is preferably located outside the feeder (1). The distance between the intersection point (2b) and the outlet is called the "intersection distance (D)" of the inclined flow path. The angle between the extrapolated lines of the inclined flow path at the intersection point (2b) from a cross-sectional perspective is called the "inclination angle (θ)" of the inclined flow path.

[0021] The plunger tube length (L) must be 10 mm or more and 40 mm or less, and when used to produce a bead foam that is a thin-walled molded product, it is preferably 15 mm or more, preferably 30 mm or less, and more preferably 27 mm or less. By using a feeder (1) having a plunger tube length (L) within the above range in a mold, a bead foam that is free of defects and has a sufficient shape, particularly a bead foam that is a thin-walled molded product, can be produced.

[0022] The inclination angle (θ) of the inclined flow path must be at least 10 degrees and less than 30 degrees, and when used to produce bead foams that are thin-walled molded products, it is preferably at least 15 degrees, more preferably at least 20 degrees and not more than 25 degrees. By using a feeder (1) whose plunger tube length (L) falls within the above range in a mold, bead foams that are free of defects and have a satisfactory shape, particularly bead foams that are thin-walled molded products, can be produced.

[0023] The intersection point (2b) of the inclined flow path is preferably located outside the feeder (1), and in this case, the intersection point distance (D) is preferably 0 mm or more and 20 mm or less. By using a feeder (1) in which the intersection point distance (D) of the inclined flow path is within the above range in a mold, defects can be further reduced and a bead foam having an improved shape, particularly a bead foam that is a thin-walled molded product, can be produced.

[0024] The tip portion (2) of the feeder (1) of the present invention may have an air vent (e.g., a slit (2c)), as shown in Fig. 4. When the tip portion (2) of the feeder (1) has an air vent (e.g., a slit (2c)), the exhaust of the air blown to introduce the foamed beads into the mold is ensured, and the molding of an insufficient bead foam, particularly a thin-walled molded product, due to a lack of foamed beads near the outlet of the feeder (1) is suppressed, which is preferable.

[0025] (Mold for Molding Bead Foam) In one embodiment, the mold for molding bead foam (200) of the present invention may have a structure, as shown in FIG. 5, in which the molding material filling space (205) of the mold (200) has a pair of opposing surfaces, the molding material filling space (205) is connected to one or more feeders (203), one of the pair of surfaces has one or more outlets (203a) for the feeders (203), and one or more of the feeders (203) is the feeder (1) of the present invention described above. The number of feeders (203) per mold (200) is not particularly limited, but the number of feeders may be increased appropriately as the size of the molded product to be molded using the mold (200) increases. The bead foam produced using such a mold may be a molded product (a flat plate-like molded product) with small thickness irregularities. The thickness of the thinnest part of the flat molded product may be 5 mm or less, and preferably 2 mm or more. By using such a mold, it is possible to produce a bead foam having a sufficient shape without defects, particularly a bead foam that is a thin-walled molded product.

[0026] In another embodiment, the bead foam molding mold (200) of the present invention may have a structure in which the molding material filling space (205) of the mold (200) has a pair of opposing surfaces, the molding material filling space (205) is connected to a plurality of feeders (203), one of the pair of surfaces has discharge outlets (203a) of the feeders (203) at a plurality of locations, the thickness of the thinnest part of the molding material filling space (205) where at least one of the discharge outlets (203a) of the feeders (203) is present is 5 mm or less, and the thickness of a portion of the molding material filling space (205) is 60 mm or less, preferably 30 mm or less, preferably 1 mm or more, and more preferably 2 mm or more. By using such a mold, bead foams having portions of different thicknesses, particularly bead foams that are thin-walled molded products, can be produced as bead foams having a sufficient shape without defects.

[0027] In any embodiment, a vent hole (e.g., a slit hole) may be present near at least one of the feeder outlets. Furthermore, a surface (hereinafter referred to as the "other surface") other than the surface having the feeder (203) outlets (203a) at multiple locations (hereinafter referred to as the "one surface") may have a core vent (204b). Furthermore, the area in the one surface where at least one feeder (203) outlet (203a) is present and the area in the other surface where at least one core vent (204c) is present may have an overlapping area with the opposing surface when viewed perpendicularly. In this case, the opening in the core vent and the opening through which the feeder can supply foamed beads may have an overlapping area when viewed perpendicularly with the opposing surface.

[0028] (Bead Foam) The bead foam of the present invention is a bead foam containing a resin, the bead foam having one or more portions corresponding to feeder discharge marks during bead foam molding, and the ratio of the density of the portions corresponding to the feeder discharge marks during bead foam molding to the average density of the entire bead foam molding is 110 to 300%. Here, the portion corresponding to the "feeder discharge mark" includes the portion corresponding to the feeder discharge mark, and includes the portion around the feeder discharge mark bearing marks caused by the feeder, feeder attachments, and the feeder attachment portion of the mold, as well as the portion subjected to pressure due to discharge from the feeder. The bead foam of the present invention may have a minimum thickness of 5 mm or less for at least one of the portions corresponding to the feeder discharge mark. Furthermore, the bead foam of the present invention may have a ratio of the modulus of elasticity of the portions corresponding to the feeder discharge mark during bead foam molding to the average modulus of elasticity of the entire bead foam molding of 120 to 600%. The bead foam of the present invention may also have a vent hole mark (e.g., a slit mark) around at least one portion corresponding to the feeder discharge mark during bead foam molding. Such a bead foam can be produced, for example, using the bead foam molding die of the present invention, and therefore can be a bead foam having a satisfactory shape without defects, particularly a bead foam that is a thin-walled molded product.

[0029] <Bead Foam Material> The bead foam of the present invention contains a resin as a material. The resin is preferably a thermoplastic resin. Examples of the thermoplastic resin include modified polyphenylene ether (m-PPE), as well as general-purpose thermoplastic resins such as polyamide, polypropylene, polystyrene, high-impact polystyrene, ABS resin, polyethylene (high density, low density), polymethyl methacrylate, polyvinylidene chloride copolymer resin, polyethylene terephthalate, polycarbonate, and mixtures thereof.

[0030] <Shape of Bead Foam> The shape of the bead foam (100) of the present invention is not particularly limited. The bead foam (100) of the present invention may have the shape of a thin-walled molded product (thin sheet), for example, as shown in Figures 8A and 8B. The bead foam (100) of the present invention is molded using a mold (200) having a molding material filling space (205) having a shape corresponding to the shape of the bead foam (100). In the present invention, the mold (200) typically has a discharge port (203a) of a feeder (203) for supplying foamed beads, which are the raw material for the bead foam (100), and core vents (204a, 204b, 204c) on the inner surface of the molding material filling space (205). The mold (200) is molded in the molding material filling space (205) of a mold (200) that combines a pair of molds (referred to as a feeder-side mold (201) and an opposing-side mold (202) for convenience in the present invention) as shown in Figures 6, 7A, and 7B, as will be described later. The bead foam (100) of the present invention that has been removed from the mold (200) after molding has a pair of opposing surfaces (101, 102), for example, in the case of a thin-walled molded product (thin sheet) as shown in Figures 8A and 8B. Of the pair of surfaces, the sheet surface that was in contact with the inner surface of the feeder-side mold (201) during molding will be referred to as the "feeder-side surface (101)," and the sheet surface that was in contact with the inner surface of the opposing-side mold (202) during molding will be referred to as the "opposing surface (102)."

[0031] <Surface Condition of Bead Foam> The feeder-side surface (101) of the bead foam (100) of the present invention has a feeder discharge mark (103) including a portion corresponding to the discharge port (203a) of the feeder (203) in the feeder-side mold (201) during bead foam molding (hereinafter also referred to as the "feeder discharge port equivalent portion" or "feeder discharge port mark"), and optionally a core vent mark (104a) including a portion corresponding to the core vent (204a) (hereinafter referred to as the "core vent equivalent portion"). One or more feeder discharge marks (103) may be present on the feeder-side surface (101). The feeder discharge mark (103) and the core vent mark (104a) may be identifiable, for example, as a feeder mark and a core vent mark, respectively. Furthermore, if the feeder has an air vent (e.g., a slit hole) near the discharge outlet, the feeder discharge mark (103) may be identifiable as an air vent mark (e.g., a slit mark) around the feeder discharge mark (e.g., the part corresponding to the feeder discharge outlet).

[0032] The opposing surface (102) of the bead foam (100) of the present invention has a portion (hereinafter referred to as the "core vent corresponding portion (104b)") that corresponds to the core vent (204b) in the opposing mold (202) used in molding the bead foam. The core vent corresponding portion (104b) may be identifiable, for example, as a core vent mark.

[0033] As will be described later, the bead foam of the present invention is produced using a mold in which an area in the feeder-side mold surface where at least one feeder is present and an area in the opposing mold surface where at least one core vent is present have an overlapping area when viewed perpendicularly from the opposing surface. Specifically, this mold has an overlapping area when viewed perpendicularly from the opposing surface between an opening in the core vent and an opening (discharge port) through which the feeder foam beads (thermoplastic resin beads) can be supplied. Taking this into consideration, it is preferable that at least one feeder discharge mark (103) in the feeder-side surface (101) of the bead foam (100) of the present invention and at least one core vent-equivalent portion (e.g., core vent-equivalent portion (104c) in Figure 7B) in the opposing surface (102) have an overlapping area when viewed perpendicularly from either the feeder-side surface (101) or the opposing surface (102).

[0034] <Thickness of Bead Foam> The thickness of the bead foam (100) of the present invention is not particularly limited. For example, the minimum thickness of the portion corresponding to the feeder discharge mark (103) (e.g., the portion corresponding to the feeder discharge port) is preferably 5.0 mm or less, more preferably 4.5 mm or less, and even more preferably 4.0 mm or less. When multiple feeder discharge marks (103) are present, it is sufficient that at least one feeder discharge mark (103) meets the above-mentioned minimum thickness range, and it is preferable that all feeder discharge marks (103) meet the above-mentioned minimum thickness range. When the minimum thickness of the portion corresponding to the feeder discharge mark in the bead foam is 5.0 mm or less, filling is generally difficult in the molding process, and filling ability tends to deteriorate, especially around the portion corresponding to the feeder discharge mark. When focusing on thin-walled portions in this way, cracking filling, as described below, is often used for filling. While cracking filling improves filling ability, it also causes problems such as deterioration in thickness accuracy, increased mold clamping force of the molding machine, and buckling of the foam.

[0035] The thickness of a portion of the bead foam of the present invention is preferably 1 mm or more, more preferably 2 mm or more, and even more preferably 7 mm or more, and is preferably 60 mm or less, more preferably 30 mm or less. Such bead foams can be simultaneously filled and molded into bead foams having portions with different thicknesses, i.e., molded products having both thin-walled and thick-walled portions, as well as into bead foams having a satisfactory shape without defects, particularly molded products having both thin-walled and thick-walled portions.

[0036] <State of expanded beads in bead foam> Average particle diameter of expanded beads in the bead foam at the part corresponding to the feeder discharge mark (1 cm across the cross section of the bead foam at the part corresponding to the feeder discharge mark) ２ The average particle diameter (per particle) is preferably 0.5 mm or more, more preferably 0.7 mm or more, even more preferably 1.0 mm or more, preferably 5.0 mm or less, more preferably 3.0 mm or less, even more preferably 2.0 mm or less, and particularly preferably 1.8 mm or less. If the average particle diameter is small, the fluid resistance of the flow path through which steam and air pass between the foamed beads during the molding process increases, which tends to lead to poor filling properties and insufficient heating. On the other hand, if the average particle diameter is too large, filling properties and shaping properties tend to deteriorate. Note that if the shape of the foamed beads in the bead foam is distorted, the circle-equivalent diameter may be used as a substitute indicator.

[0037] The flatness of the foamed beads in the foamed beads (1 cm cross section of the foamed beads in the part corresponding to the feeder discharge mark) ２The average value of ((maximum in-plane diameter - maximum thickness diameter) / maximum in-plane diameter) per unit area is preferably 0.7 or less, more preferably 0.5 or less, and even more preferably 0.3 or less. A flattening ratio of 0 indicates that the foamed beads are not crushed at all and have a circular cross section (no flattening). A smaller flattening ratio (closer to 0) indicates that the foamed beads are less crushed (low flattening). A larger flattening ratio (closer to 1.0) indicates that the foamed beads are more crushed (high flattening). A large degree of crushing of the foamed beads significantly reduces the cushioning properties of the foam. Generally, when the flattening ratio of foamed beads is large, the amount of cracking during the cracking filling process (described below) tends to be large, which can lead to a deterioration in thickness accuracy, an increase in the clamping force of the molding machine, and buckling of the foam. The terms "in-plane direction" and "thickness direction" refer to the directions corresponding to the "in-plane direction" (i.e., the direction along the surface) and "thickness direction" (i.e., the direction corresponding to the thickness of the surface) in the bead foam, respectively.

[0038] The number of foamed beads in the bead foam in the thickness direction (1 cm cross section of the part corresponding to the feeder discharge mark on the cross section of the bead foam) ２ The average number of foamed beads in the thickness direction per unit area is preferably 1.2 or more, more preferably 2.0 or more, and even more preferably 3.0 or more. There is no particular upper limit, but it is preferably 15 or less, more preferably 10 or less, and even more preferably 8 or less. If the number in the thickness direction is too large, the efficiency of heating by steam will be reduced, and if it is too small, the strength of the foamed bead will be insufficient.

[0039] In addition, when there are multiple feeder discharge marks (103), it is sufficient that at least one feeder discharge mark (103) satisfies the above-mentioned ranges of average particle diameter, flatness, and number of foamed beads in the thickness direction, and it is preferable that all feeder discharge marks (103) satisfy the above-mentioned ranges of average particle diameter, flatness, and number of foamed beads in the thickness direction.

[0040] <Bead foam having a runner portion> In another embodiment, the bead foam (100) of the present invention may have a runner portion (112), as shown in Figures 12A and 12B. In this case, the bead foam (100) of the present invention is divided into a main body portion (111) and a runner portion (112). The feeder discharge marks (103) may be present inside the runner portion (112) or at the boundary between the main body portion (111) and the runner portion (112). Such a bead foam (100) can be molded using a mold (200) that combines a feeder-side mold (201) and an opposing mold (202), as shown in Figures 11A and 11B. When the bead foam (100) of the present invention has a runner portion (112), after molding, the runner portion (112') may be separated from the bead foam (100) and the remaining main body portion (111') may be used, as shown in Figure 12C. Furthermore, when the runner portion is separated and used, even if there is a filling defect in the runner portion, it is acceptable as long as there is no filling defect in the main body portion.

[0041] The runner portions (112) may lie perpendicular to the plane of the bead foam (100), or alternatively, the runner portions (112) may lie in the plane of the bead foam (100).

[0042] <Expanded beads> The material of the expanded beads is the same as that of the bead foam to be produced, and contains a resin. The resin is preferably a thermoplastic resin, and specific examples thereof include those mentioned above.

[0043] The average particle size of the foamed beads is preferably 0.5 mm or more, more preferably 0.7 mm or more, even more preferably 1.0 mm or more, preferably 5.0 mm or less, more preferably 3.0 mm or less, even more preferably 2.0 mm or less, and particularly preferably 1.8 mm or less. If the average particle size is small, the width of the flow path when steam or air passes between the foamed beads during the molding process tends to be narrowed, which tends to cause poor filling properties and insufficient heating. On the other hand, if the average particle size is too large, filling properties and shaping properties tend to be poor.

[0044] The expanded beads used in the method for producing a bead foam described below can be obtained by incorporating (impregnating) a blowing agent into a base resin composition and causing foaming (this step is referred to as the "bead expansion step"). Specifically, for example, a method similar to that described in Example 1 of JP-A-4-372630 includes placing a base resin composition (in the form of pellets, beads, or the like) in a pressure-resistant container, replacing the gas in the container with dry air, and then pressurizing and impregnating the base resin composition with the blowing agent (gas), and then releasing the pressure to transfer the base resin composition pellets from the pressure container to a foaming furnace, and then heating and foaming the base resin composition pellets in the foaming furnace with pressurized steam while rotating a stirring blade, thereby producing expanded beads. The conditions for impregnating the base resin composition with a blowing agent (gas) according to the above method are not particularly limited, and from the viewpoint of more efficiently impregnating the base resin composition with the blowing agent (gas), for example, an impregnation pressure of 0.3 to 30 MPa, an impregnation temperature of −20 to 100° C., and an impregnation time of 10 minutes to 96 hours are preferred. In addition, from the viewpoint of easily achieving a desired expansion ratio and improving the appearance, the maximum vapor pressure of the pressurized steam in the foaming furnace is preferably 30 to 700 kPa·G.

[0045] The blowing agent is not particularly limited, and commonly used gases can be used. Examples thereof include inorganic gases such as air, carbon dioxide gas, nitrogen gas, oxygen gas, ammonia gas, hydrogen gas, argon gas, helium gas, and neon gas; fluorocarbons such as trichlorofluoromethane (R11), dichlorodifluoromethane (R12), chlorodifluoromethane (R22), tetrachlorodifluoroethane (R112), dichlorofluoroethane (R141b), chlorodifluoroethane (R142b), difluoroethane (R152a), HFC-245fa, HFC-236ea, HFC-245ca, and HFC-225ca; saturated hydrocarbons such as propane, n-butane, i-butane, n-pentane, i-pentane, and neopentane; dimethyl ether, diethyl ether, methyl ethyl ether, isopropyl ether, n-butyl ether, diisopropyl ether, furan, fluorocarbons, and the like. Examples of suitable ethers include fural, 2-methylfuran, tetrahydrofuran, and tetrahydropyran; ketones such as dimethyl ketone, methyl ethyl ketone, diethyl ketone, methyl n-propyl ketone, methyl n-butyl ketone, methyl i-butyl ketone, methyl n-amyl ketone, methyl n-hexyl ketone, ethyl n-propyl ketone, and ethyl n-butyl ketone; alcohols such as methanol, ethanol, propyl alcohol, i-propyl alcohol, butyl alcohol, i-butyl alcohol, and t-butyl alcohol; carboxylic acid esters such as methyl formate, ethyl formate, propyl formate, butyl formate, amyl formate, methyl propionate, and ethyl propionate; and chlorinated hydrocarbons such as methyl chloride and ethyl chloride. These may be used alone or in combination of two or more.

[0046] From the viewpoint of flame retardancy, it is preferable that the blowing agent has no or little flammability and flame-supporting properties, and from the viewpoint of gas safety, inorganic gases are more preferable. Furthermore, inorganic gases are less soluble in resins than organic gases such as hydrocarbons, and are easily degassed from the resin after the foaming or molding process, which has the advantage of providing superior dimensional stability over time for the molded foam. Furthermore, when inorganic gases are used, plasticization of the resin due to residual gas is less likely to occur, and excellent heat resistance can be easily achieved at an earlier stage without undergoing a process such as aging. Among inorganic gases, carbon dioxide is preferred from the viewpoints of solubility in resins and ease of handling. Furthermore, hydrocarbon-based organic gases are generally highly flammable, and if they remain in the foam, they tend to deteriorate the flame retardancy.

[0047] (Mold) A mold (200) for molding the bead foam (100) of the present invention is, for example, as shown in Figures 6, 7A, and 7B, a mold for molding bead foam, in which the molding material filling space (205) of the mold (200) has a pair of opposing surfaces, one of which has a discharge outlet (203a) of a feeder (203), and the other surface has a core vent (204b), the thickness of the molding material filling space (205) where the discharge outlet of the feeder (203) is present is 5 mm or less, and the region in one surface where at least one discharge outlet (203a) of the feeder (203) is present and the region in the other surface where at least one core vent (204c) is present overlap with the opposing surface when viewed perpendicularly (the opening portion of the core vent and the opening portion of the feeder through which foamed beads can be supplied may also overlap with each other when viewed perpendicularly to the opposing surface).

[0048] 6, 7A, and 7B show a mold (200) that combines a feeder-side mold (201) and an opposing mold (202), where the "one side" having the discharge port of the feeder (203) is present in the feeder-side mold (201), and the "other side" having the core vent (204b) is present in the opposing mold (202). For convenience, the "one side" and the "other side" are referred to as the "inner surface of the feeder-side mold (201)" and the "inner surface of the opposing mold (202)," respectively. The inner surface of the feeder-side mold (201) may optionally have a core vent (204a). Furthermore, the area on the inner surface of the feeder-side mold (201) where at least one discharge outlet of the feeder (203) is present and the area on the inner surface of the opposing-side mold (202) where at least one core vent (204c) is present may have an overlapping area when viewed perpendicularly to the opposing surfaces, making it possible to mold a bead foam (100) as a thin-walled molded product (thin-walled sheet).

[0049] <Feeder> The feeder (203) is a transfer pipe for introducing the foamed beads (150) into the molding material filling space (205). One or more feeders (203) may be present. Furthermore, the feeder-side mold (201) may have one or more discharge outlets (203a) for the feeders (203) on the inner surface of the mold. The shape of the tip (discharge outlet) of the feeder (203) on the molding material filling space side is not particularly limited. For example, at least one of the discharge outlets (203a) of the feeder (203) may have an unmodified pipe tip shape as shown in FIG. 9A or a pipe tip shape having an air hole (e.g., a slit (206)) as shown in FIG. 9B. It is preferable that the feeder (203) has an air vent (e.g., a slit (206)) at the tip (discharge port (203a)) on the molding material filling space side, since this ensures the discharge of the air blown to introduce the foamed beads (150) and prevents the formation of insufficient thin-walled molded products due to insufficient filling of the foamed beads (150) near the feeder (203).

[0050] <Core Vent> The filler used as the core vents (204a, 204b, 204c) (hereinafter also collectively referred to as "core vents (204)") is not particularly limited, but examples thereof include those having the shape shown in Fig. 10. For the core vents (204) arranged in a location that has an overlapping area in a perspective perpendicular to the surface facing the area where the discharge port of the feeder is present, the total opening area (mm ２ ) is, for example, 1 mm ２ More than 5 mm is preferable. ２ More preferably, 9 mm or more ２ More preferably, 300 mm or more ２ Preferably less than 200 mm ２ Less than 180 mm is more preferable. ２ The following is more preferable. The size (diameter of the outer periphery of the part through which air or steam passes) of the core vent (204) arranged in a location having an overlapping region when viewed perpendicular to the surface opposite the region where the feeder outlet is located is, for example, preferably 2 mm or more, more preferably 3 mm or more, even more preferably 5 mm or more, preferably 30 mm or less, more preferably 15 mm or less, and even more preferably 20 mm or less. The slit width of the core vent (204) arranged in a location having an overlapping region when viewed perpendicular to the surface opposite the region where the feeder outlet is located is preferably 0.05 mm or more, more preferably 0.10 mm or more, and even more preferably 0.15 mm or more. Also, it is preferably 2.0 mm or less, more preferably 1.5 mm or less, and even more preferably 1.0 mm or less. It is preferable that the opening area, diameter, and slit width are within the above ranges from the viewpoint of effectively forming a flow path for air introduced from the feeder during filling, from the viewpoint of easily heating the foamed beads present in the vicinity of the feeder during the heating step, and from the viewpoint of making the core vent marks remaining on the foamed bead body after molding less conspicuous. Also, in the core vent (204) arranged in a place having an overlapping area in a perspective perpendicular to the surface facing the area where the discharge port of the feeder is present, the total opening area of ​​the core vent (mm ２) / The perimeter (mm) of the outer periphery of the core vent opening can be used as an index to consider the relative width of the flow path through which air or steam flows, and if the opening area is the same, the total opening area (mm ２ ) / The larger the perimeter (mm) of the opening, the wider the flow path, which reduces fluid resistance and allows air and steam to flow more effectively. ２ ) / perimeter length (mm) of the opening is preferably 0.01 or more, more preferably 0.09 or more, and even more preferably 0.19 or more.

[0051] From the same viewpoint as above, the sum of the overlapping areas between the opening portion of the core vent (204) arranged at a location having an overlapping area in a perspective perpendicular to the surface opposite to the area where the outlet of the feeder is present and the opening portion of the outlet of the feeder, the perimeter of the overlapping area, and the sum of the overlapping areas / perimeter of the overlapping area can be defined. The sum of the overlapping areas, the perimeter of the overlapping area, and the sum of the overlapping areas / perimeter of the overlapping area are particularly important because they relate to the portion that essentially functions as a flow path through which air flows when the foamed beads are filled. The sum of the overlapping areas between the opening portion of the core vent (204) arranged at a location having an overlapping area in a perspective perpendicular to the surface opposite to the area where the outlet of the feeder is present and the opening portion of the outlet of the feeder can be defined as, for example, 1 mm ２ More than 5 mm is preferable. ２ More preferably, 9 mm or more ２ More preferably, 300 mm or more ２ Preferably less than 200 mm ２ Less than 180 mm is more preferable. ２The following is more preferable. The size of the overlapping portion between the opening of the core vent (204) arranged at a location having an overlapping area in a perspective perpendicular to the surface opposite to the area where the outlet of the feeder is present and the opening of the outlet of the feeder (diameter of the outer periphery of the part through which air or steam passes) is, for example, preferably 2 mm or more, more preferably 3 mm or more, even more preferably 5 mm or more, preferably 30 mm or less, more preferably 15 mm or less, and even more preferably 20 mm or less. In addition, the total overlapping area (mm ２ ) / overlap perimeter (mm) can be used as an index to consider the relative width of the flow path through which air or steam flows, and if the overlap area is the same, the sum of the overlap areas (mm ２ ) / The larger the overlap perimeter (mm), the wider the flow path, which reduces fluid resistance and allows air and steam to flow more effectively. ２ ) / overlapping portion circumferential length (mm) is preferably 0.01 or more, more preferably 0.09 or more, and even more preferably 0.19 or more.

[0052] <Thickness of molding material filling space> The thickness of the molding material filling space (205) is set according to the thickness of the bead foam (100) to be molded, and the thickness of the molding material filling space (205) at the portion where the discharge outlet of the feeder (203) is located is 5 mm or less, preferably 4.5 mm or less, and more preferably 4.0 mm or less. When the thickness of the molding material filling space (205) at the portion where the discharge outlet of the feeder (203) is located is 5 mm or less, filling is generally difficult during the molding process, and filling tends to deteriorate particularly around the portion corresponding to the feeder discharge outlet. When focusing on thin-walled portions in this way, cracking filling, as described below, is generally used for filling. While cracking filling improves filling, it can also cause problems such as a deterioration in thickness accuracy, an increase in the clamping force of the molding machine, and buckling of the foam.

[0053] <Mold with Runner Region> In another embodiment, for example, when molding a bead foam (100) having a runner portion (112) as shown in Figures 12A and 12B, the molding material filling space (205) of the mold (200) may have a portion (runner region (212a, 212b)) corresponding to the runner portion (112). In this case, the runner region (212a) on the inner surface of the feeder-side mold (201) has the discharge outlet (203a) of the feeder (203). Furthermore, the thickness of the molding material filling space (205) at the boundary between the portion 112 where the discharge outlet (203a) of the feeder (203) is present and the main body portion 111 is preferably 5 mm or less, more preferably 4.5 mm or less, and even more preferably 4.0 mm or less. In the molding material filling space (205), the portions other than the runner regions (212a, 212b) become the main body regions (211a, 211b).

[0054] (Method for Producing Bead Foam) The bead foam of the present invention can be produced, for example, by the following production method (hereinafter referred to as the "production method of the present invention"). A method for producing a bead foam comprising the following steps: a step of filling a molding material filling space of a mold with thermoplastic resin beads via one or more feeders; and a step of performing bead expansion molding on the thermoplastic resin beads filled in the molding material filling space of the mold to form a bead foam, wherein the molding material filling space of the mold has a pair of opposing surfaces, one of the pair of surfaces has one or more outlets for the feeders, and an intersection of the air flow paths of the feeders is present in the molding material filling space.

[0055] The bead foam of the present invention may also be produced by an in-mold foaming method. In this case, the method for molding a foam using foamed beads is not particularly limited, but examples include a method in which foamed beads are filled into a molding material filling space, heated to thermally fuse the foamed beads together, and then cooled to solidify the product and mold it (this process is also referred to as an in-mold foaming method). The method for filling the foamed beads is not particularly limited, and known methods can be used. In the in-mold foaming method, a mold of the desired shape is prepared, and foamed beads are filled therein to mold the foam, making it easy to mold the foam into finer or more complex shapes. Furthermore, the in-mold foaming method makes it easy to increase the expansion ratio of the foam, and the resulting foam is likely to exhibit flexibility in addition to heat insulation properties.

[0056] In the production method of the present invention, the feeder of the present invention described above can be used as at least one of the feeders, and the mold of the present invention described above can be used as the mold.

[0057] The manufacturing method of the present invention is a method for producing a bead foam by an in-mold foaming method. In the in-mold foaming method, a mold of the desired shape is prepared and foam beads are filled into the mold to form the foam, which makes it easy to form the foam into a finer or more complex shape. Furthermore, the in-mold foaming method makes it easy to increase the expansion ratio of the foam, and the resulting foam is likely to exhibit flexibility in addition to heat insulation properties.

[0058] Before filling the molding material filling space with the foamed beads, the foamed beads may be subjected to a gas pressure treatment. By applying a certain gas pressure to the bubbles of the foamed beads, the foamed beads expand during the heating process, firmly fusing the foamed beads that make up the resulting foam, thereby improving the rigidity and appearance of the molded body. The gas used for the pressure treatment is not particularly limited, but air and inorganic gases are preferred from the standpoints of ease of handling and economy. The pressure treatment method is not particularly limited, but examples include a method in which the foamed beads are filled into a pressure vessel, and then a pressurized gas is introduced and the pressure is increased to a maximum pressure of 0.1 to 20 MPa over a period of 10 minutes to 96 hours, thereby supplying the gas into the pressure vessel.

[0059] The expansion ratio of the foamed beads is 1.5 cm from the viewpoint of improving lightness. ３ / g or more, and more preferably 2.0 cm ３ / g or more, more preferably 2.5 cm ３ From the viewpoint of improving mechanical strength and flame retardancy, the expansion ratio of the expanded beads is 100 cm ３ / g or less, and more preferably 50 cm ３ / g or less, more preferably 30 cm ３ / g or less.

[0060] Examples of methods for filling foamed beads include the cracking method, in which the mold is slightly open when filling, the compression method, in which compressed beads are filled by applying pressure while the mold is closed, and the compression cracking method, in which compressed beads are filled and then cracked. Cracking methods are often used when filling is poor because they improve filling performance without requiring any special mold modifications and are less likely to worsen cycle time. However, from the viewpoints of the following, a cracking rate of 200% or less is preferred, 100% or less is more preferred, and 50% or less is even more preferred. A cracking rate of 0% (a method in which foamed beads are filled in a fully closed mold without using the cracking method) is preferred, but filling performance tends to be significantly worse when the thickness of the molding material filling space is 10 mm or less, especially 5 mm or less. Cracking rate (%) = (thickness of molding material filling space (mm) + amount of cracking (mm)) / thickness of molding material filling space (mm) × 100 *Amount of cracking: distance (mm) by which the mold is opened during filling. The pressure of the filling air during filling is preferably 0.1 MPaG or more, more preferably 0.2 MPaG or more, and even more preferably 0.3 MPaG or more. It is also preferably 1.0 MPaG or less, more preferably 0.8 MPaG, and even more preferably 0.6 MPaG or less. A filling air pressure within the above range is preferred from the viewpoints of preventing filling defects due to air interference during filling and of facilitating the transfer of the bead foam. The filling time (the time required for the process of filling the foamed beads) is preferably 1 s or more, more preferably 2 s or more, and even more preferably 3 s or more. It is also preferably 20 s or less, more preferably 15 s or less, and even more preferably 10 s or less. It is preferable that the filling time is within the above range, from the viewpoint of preventing deterioration of the cycle time and from the viewpoint of facilitating filling of the foamed beads into the molding material filling space in the mold.

[0061] Examples of heating methods for molding foamed beads include heating using a heat medium such as water vapor, heating with a heater such as an IR heater, and heating using microwaves. When heating using a heat medium, a general-purpose heat medium may be used, and water vapor is preferred from the viewpoint of efficiently heating the resin. A method for molding a foamed bead using water vapor (steam foam molding) generally uses a mold having a core vent and may include a step of replacing the air in the mold and between the foamed beads with steam, called one-sided / reverse one-sided heating, a step of introducing steam from both sides of the mold to sufficiently heat the foamed beads and fuse them together, called double-sided heating, and a cooling step of spraying water on the heated product to cool it.

[0062] When the heating temperature of the foamed beads is high, the foamed beads tend to fuse together and the residual stress in the bead foam is easily reduced, which tends to improve moldability, the appearance of the molded product, and heat resistance. However, if the heating temperature is too high, the bead foam tends to shrink and warp. Furthermore, if the heating time of the foamed beads is long, the foamed beads tend to fuse together and the residual stress in the bead foam is easily reduced, which tends to improve moldability and heat resistance. However, if the heating time is too long, the bead foam may shrink and warp, or the cycle time may be shortened, resulting in poor moldability. From the above perspectives, the heating temperature of the foamed beads in the molding process is preferably 50 to 200°C, more preferably 70 to 160°C, and even more preferably 80 to 150°C.

[0063] <Method for producing a bead foam having a runner portion> A bead foam having a runner portion can be produced by the in-mold foaming method described above, and a bead foam having a desired shape can be obtained by cutting off the runner portion after molding.

[0064] The present invention will be described in detail below with reference to specific examples and comparative examples, but the present invention is not limited to the following examples. The measurement and evaluation methods used in the examples and comparative examples are shown below.

[0065] [Method for measuring the thinnest part] The thickness of the thinnest part of the bead foam, in the direction perpendicular to the plane of the bead foam, is measured at the part corresponding to the feeder discharge mark during bead foam molding. If there are multiple feeders, the part corresponding to the feeder discharge mark is selected and cut out, and the thinnest thickness of that part is taken as the thickness of the thinnest part.

[0066] [Expansion Ratio of Foam] Samples were prepared with a size of approximately 30 mm square and 10 mm thick, referring to the preparation method of each foam. The mass W (g) of the sample was measured, and the volume V (cm ３ ) divided by the mass W, V / W is the expansion ratio (cm ３ / g).

[0067] [Flatness of foamed beads in foamed beads] The flatness of foamed beads in the foamed beads (1 cm across the cross section of the foamed beads in the cross section corresponding to the feeder discharge mark) was measured directly below the part corresponding to the feeder discharge mark. ２ The average value of ((maximum in-plane diameter - maximum thickness diameter) / maximum in-plane diameter) per 1000 mm was calculated. The shape of the foamed beads in the bead foam was analyzed based on the cross-sectional shape of the foamed beads in a cross-sectional image obtained by cutting the bead foam in a direction perpendicular to the plane of the bead foam and observing the cross-section with a microscope (Keyence 3D Real Surface View Microscope VE-9800). From the cross-sectional image obtained, the maximum in-plane and thickness directions were measured for each foamed bead visible in the cross-section of the bead foam, and the oblateness was calculated. When the total cross-sectional area observed by the same procedure was 1 cm2, the average value of the in-plane and thickness directions was calculated. ２ Repeat until it is more than 1 cm ２ The flatness of the foamed beads per unit area was calculated.

[0068] [Number of foamed beads in the thickness direction in the foamed beads] The number of foamed beads in the foamed beads in the thickness direction immediately below the part corresponding to the feeder discharge mark (1 cm across the cross section of the foamed beads in the part corresponding to the feeder discharge mark) ２The average number of foamed beads in the thickness direction per square meter was calculated. The shape of the foamed beads in the bead foam was analyzed based on the cross-sectional shape of the foamed beads in a cross-sectional image obtained by cutting the bead foam in a direction perpendicular to the plane of the bead foam and observing the cross-section with a microscope (Keyence Corporation 3D Real Surface View Microscope VE-9800). A line (measurement line) was drawn in the thickness direction on the obtained cross-sectional image, and the number of foamed beads contained on the line was counted. When the total cross-sectional area observed by the same procedure was 1 cm, ２ The above procedure was repeated until the number of measurement lines reached 30 or more, and the average number of foamed beads in the thickness direction of the bead foam was calculated. The intervals between the measurement lines were made as even as possible to prevent the number of foamed beads in the thickness direction on each measurement line from being arbitrary.

[0069] [Filling property in the part just below the part corresponding to the feeder discharge port] For Examples 1 to 19 and Comparative Examples 1 to 4, the filling property in the part just below the part corresponding to the feeder discharge mark was evaluated as follows for the obtained bead foams. The area of ​​the part where there is a lack of filling (a state where foamed beads are not filled and a defect has occurred) when viewed from a direction perpendicular to the surface of the molded body is: Unfilled area 0 mm ２ In the case of: S (no gap) gap area 0 mm ２ Larger than 5mm ２ In the following cases: A (almost no missing filling, no practical problems) Missing filling area 5 mm ２ Larger by 10mm ２ In the following cases: B (there is a small amount of missing filling, but it does not cause any problems in practical use) Missing filling area: 10 mm ２ Larger than 20mm ２ In the following cases: C (there is a small amount of missing filling, but it does not cause any practical problems) Missing filling area: 20 mm ２ Larger than 30mm ２ In the following cases: D (missing filling) Missing filling area 30 mm ２ If larger: E (large underfill)

[0070] For Examples 20 to 34 and Comparative Examples 5 to 6, the fillability of the obtained bead foams in the area directly below the area corresponding to the feeder discharge marks was evaluated as follows: The area of ​​the area where there was a lack of filling (a state where foamed beads were not filled and a defect was formed) when viewed from a direction perpendicular to the surface of the molded body was: Unfilled area 0 mm ２ In the case of: +++ (no missing filling) Missing filling area 0 mm ２ Larger than 30mm ２ In the following cases: ++ (slightly missing filling, but no practical problem) Missing filling area: 30 mm ２ Larger than 100mm ２ In the following cases: + (with incomplete filling) 100 mm ２ If larger: NG (large underfill)

[0071] Example 1: 60% by mass of polyphenylene ether resin ("S201A" manufactured by Asahi Kasei Corporation), 15% by mass of bisphenol A-bis(diphenyl phosphate) (BBP) (melting point 20°C or less) as a non-halogen flame retardant, 10% by mass of high impact polystyrene resin (HIPS) with a rubber concentration of 6% by mass, and 15% by mass of GP685 (manufactured by PS Japan Co., Ltd.) as a general-purpose polystyrene resin (PS) were mixed, and the mixture was heated, melted, and kneaded in an extruder, followed by extrusion to prepare base resin composition pellets. In accordance with the method described in Example 1 of JP-A-4-372630, base resin composition pellets were placed in a pressure-resistant vessel, the gas in the vessel was replaced with dry air, and carbon dioxide (gas) was injected as a blowing agent. The base resin composition pellets were impregnated with carbon dioxide over a period of 3 hours under conditions of a pressure of 3.0 MPa and a temperature of 10°C. The base resin composition pellets were then immediately transferred after removal from the pressure vessel and foamed in a foaming furnace with pressurized steam at a maximum pressure of 330 kPa·G while rotating the stirring blades at 77 rpm, yielding foamed beads with an average particle size of 1.8 mm. The hydrocarbon gas content of the foamed beads was measured by gas chromatography immediately after foaming and was found to be below the detection limit (0.01% by mass). The foamed beads were then placed in a vessel and pressurized by introducing pressurized air (increasing the pressure to 0.4 MPa over 4 hours, and then maintaining the pressure at 0.4 MPa for 16 hours). This was filled into a 150 mm x 150 mm mold having one feeder structure as shown in Figure 5 (filling conditions: filling air pressure 0.5 MPaG, filling time 5 seconds, cracking rate 10%), heated with steam to expand and fuse the foamed beads together, then cooled and removed from the molding mold to obtain a bead foam. Each feeder had an outer diameter of φ28 mm and a plunger diameter of φ10 mm. The inclination angle, plunger tube length, and intersection distance (minus marks indicate that the intersection point was located inside the feeder) were as shown in Table 1. There was no slit at the tip of the feeder. The cracking rate during molding was 10%. The foam thickness was 3 mm across the entire surface, and the ratio of the density of the area corresponding to the feeder discharge mark to the average density of the entire foam was approximately 200%. The evaluation results of the filling ability of the foam are shown in Table 1.

[0072] Examples 2 to 17, Comparative Examples 1 to 4: Bead foams were produced and evaluated in the same manner as in Example 1, except that the inclination angle of the feeder, the plunger tube length, the intersection distance, and the presence or absence of a slit at the tip of the feeder were changed as shown in Table 1. The thickness of the foam and the density ratio of the part corresponding to the feeder discharge mark were similar to those in Example 1.

[0073] Example 18: 60 mass% of polyphenylene ether resin ("S201A" manufactured by Asahi Kasei Corporation), 15 mass% of bisphenol A-bis(diphenyl phosphate) (BBP) (melting point 20°C or less) as a non-halogen flame retardant, 10 mass% of high impact polystyrene resin (HIPS) with a rubber concentration of 6 mass%, and 15 mass% of GP685 (manufactured by PS Japan Co., Ltd.) as a general-purpose polystyrene resin (PS) were mixed, and the mixture was heated, melted, and kneaded in an extruder, followed by extrusion to prepare base resin composition pellets. In accordance with the method described in Example 1 of JP-A-4-372630, base resin composition pellets were placed in a pressure-resistant vessel, the gas in the vessel was replaced with dry air, and carbon dioxide (gas) was injected as a blowing agent. The base resin composition pellets were impregnated with carbon dioxide over a period of 3 hours under conditions of a pressure of 3.0 MPa and a temperature of 10°C. The base resin composition pellets were then immediately transferred after removal from the pressure vessel and foamed in a foaming furnace with pressurized steam at a maximum pressure of 330 kPa·G while rotating the stirring blades at 77 rpm, yielding foamed beads with an average particle size of 1.8 mm. The hydrocarbon gas content of the foamed beads was measured by gas chromatography immediately after foaming and was found to be below the detection limit (0.01% by mass). The foamed beads were then placed in a vessel and pressurized by introducing pressurized air (increasing the pressure to 0.4 MPa over 4 hours, and then maintaining the pressure at 0.4 MPa for 16 hours). This was filled into a 700 mm x 500 mm mold having nine feeders with the structure shown in Figure 5 (filling conditions: filling air pressure 0.5 MPaG, filling time 5 seconds, cracking rate 10%), heated with steam to expand and fuse the foamed beads together, then cooled and removed from the molding mold to obtain a bead foam. Each feeder had an outer diameter of φ28 mm and a plunger diameter of φ10 mm. The inclination angle, plunger tube length, and intersection distance (minus marks indicate that the intersection point was located inside the feeder) were as shown in Table 1. There were no slits at the tip of the feeder. The cracking rate during molding was 10%. The foam thickness was 3 mm across the entire surface, and the ratio of the density of the area corresponding to the feeder discharge marks to the average density of the entire foam was approximately 200%. The evaluation results of the filling ability of the foam are shown in Table 1.It was shown that even when multiple feeders were installed, uniform filling was possible except for the areas corresponding to the feeder discharge marks.

[0074] Example 19: 60 mass% of polyphenylene ether resin ("S201A" manufactured by Asahi Kasei Corporation), 15 mass% of bisphenol A-bis(diphenyl phosphate) (BBP) (melting point 20°C or less) as a non-halogen flame retardant, 10 mass% of high impact polystyrene resin (HIPS) with a rubber concentration of 6 mass%, and 15 mass% of GP685 (manufactured by PS Japan Co., Ltd.) as a general-purpose polystyrene resin (PS) were mixed, and the mixture was heated, melted, and kneaded in an extruder, followed by extrusion to prepare base resin composition pellets. In accordance with the method described in Example 1 of JP-A-4-372630, base resin composition pellets were placed in a pressure-resistant vessel, the gas in the vessel was replaced with dry air, and carbon dioxide (gas) was injected as a blowing agent. The base resin composition pellets were impregnated with carbon dioxide over a period of 3 hours under conditions of a pressure of 3.0 MPa and a temperature of 10°C. The base resin composition pellets were then immediately transferred after removal from the pressure vessel and foamed in a foaming furnace with pressurized steam at a maximum pressure of 330 kPa·G while rotating the stirring blades at 77 rpm, yielding foamed beads with an average particle size of 1.8 mm. The hydrocarbon gas content of the foamed beads was measured by gas chromatography immediately after foaming and was found to be below the detection limit (0.01% by mass). The foamed beads were then placed in a vessel and pressurized by introducing pressurized air (increasing the pressure to 0.4 MPa over 4 hours, and then maintaining the pressure at 0.4 MPa for 16 hours). This was filled into a 700 mm x 500 mm mold having nine feeders with the structure shown in Figure 5 (filling conditions: filling air pressure 0.5 MPaG, filling time 5 seconds, cracking rate 10%), heated with steam to expand and fuse the foamed beads together, then cooled and removed from the molding mold to obtain a bead foam. Each feeder had an outer diameter of φ28 mm and a plunger diameter of φ10 mm. The inclination angle, plunger tube length, and intersection distance (minus marks indicate that the intersection point was located inside the feeder) were as shown in Table 1. A slit was provided at the tip of the feeder. The cracking rate during molding was 10%. The foam thickness was 3 mm across the entire surface, and the ratio of the density of the area corresponding to the feeder discharge marks to the average density of the entire foam was approximately 200%. The evaluation results of the filling ability of the foam are shown in Table 1.It was shown that even when multiple feeders were installed, uniform filling was possible except for the areas corresponding to the feeder discharge marks.

[0075]

[0076]

[0077] Example 20: 60 mass% of polyphenylene ether resin ("S201A" manufactured by Asahi Kasei Corporation), 15 mass% of bisphenol A-bis(diphenyl phosphate) (BBP) (melting point 20°C or less) as a non-halogen flame retardant, 10 mass% of high impact polystyrene resin (HIPS) with a rubber concentration of 6 mass%, and 15 mass% of GP685 (manufactured by PS Japan Co., Ltd.) as a general-purpose polystyrene resin (PS) were mixed, and the mixture was heated, melted, and kneaded in an extruder, followed by extrusion to prepare base resin composition pellets. In accordance with the method described in Example 1 of JP-A-4-372630, base resin composition pellets were placed in a pressure-resistant vessel, the gas in the vessel was replaced with dry air, and carbon dioxide (gas) was injected as a blowing agent. The base resin composition pellets were impregnated with carbon dioxide over a period of 3 hours under conditions of a pressure of 3.0 MPa and a temperature of 10°C. The base resin composition pellets were then immediately transferred after removal from the pressure vessel and foamed in a foaming furnace with pressurized steam at a maximum pressure of 330 kPa·G while rotating the stirring blades at 77 rpm, yielding foamed beads with an average particle size of 1.8 mm. The hydrocarbon gas content of the foamed beads was measured by gas chromatography immediately after foaming and was found to be below the detection limit (0.01% by mass). The foamed beads were then placed in a vessel and pressurized by introducing pressurized air (increasing the pressure to 0.4 MPa over 4 hours, and then maintaining the pressure at 0.4 MPa for 16 hours). This was filled into the molding dies shown in Figures 14 to 29 (filling conditions: filling air pressure 0.4 MPaG, filling time 5 seconds, cracking rate 0%) and heated with steam to expand and fuse the foamed beads together, after which they were cooled and removed from the molding dies to obtain a bead foam. The molding dies shown in Figures 14 to 23 and Figures 27 and 28 have a core vent on the surface facing the discharge outlet of the feeder used in molding the bead foam, and the shape of the opening of this core vent is shown in Figure 30. Table 2 shows an overview of the mold design, molding process conditions (cracking rate), and evaluation results of the foam.

[0078] Examples 21 to 34, Comparative Examples 5 to 6: Bead foams were produced and evaluated in the same manner as in Example 20, except that the mold design outline and molding process conditions (cracking rate) were changed as shown in Table 2.

[0079]

[0080]

[0081] According to the present invention, in the production of bead foams, particularly bead foams that are thin-walled molded products, it is possible to produce bead foams that are free of defects and have a satisfactory shape. In particular, the bead foams that are thin-walled molded products produced in this manner are suitable for use in automobiles, wireless communication, and the like.

[0082] REFERENCE SIGNS LIST 1 Feeder of the present invention 1a Discharge port of feeder of the present invention 2 Tip portion (front pipe) 2a Inclined portion 2b Intersection point 2c Vent hole (slit) 3 Main pipe portion 4 Branch pipe 5 Plunger 6 Rod 100 Bead foam 101 Feeder side surface 102 Opposite side surface 103 Feeder discharge mark 104a Core vent mark (in feeder side surface) 104b Core vent mark (in opposite side surface) 104c Core vent mark (located at feeder discharge mark in opposite side surface) 111 Main body portion 111' Main body after cutting 112 Runner portion 112' Runner after cutting 200 Mold 201 Feeder side mold 202 Opposite side mold 203 Feeder 203a Feeder discharge port 204 Core vent 204a Core vent (inside the feeder side mold) 204b Core vent (inside the opposing side mold) 204c Core vent (located in the portion corresponding to the feeder in the opposing side mold) 205 Molding material filling space 211a Main body region (inside the feeder side mold) 211b Main body region (inside the opposing side mold) 212a Runner region (inside the feeder side mold) 212b Runner region (inside the opposing side mold) L Plunger pipe length D Intersection distance θ Tilt angle

Claims

1. A feeder for filling beads, comprising: The plunger tube length at the tip of the feeder is 10 mm or more and 40 mm or less, The inclination angle of the inclined flow path at the tip portion of the feeder is 10 degrees or more and less than 30 degrees. Feeder for filling beads.

2. The intersection distance of the inclined flow path at the tip portion of the feeder is 0 mm or more and 20 mm or less. A feeder for filling beads according to claim 1.

3. The tip portion of the feeder has a slit.

3. A feeder for filling beads according to claim 1 or 2.

4. A bead foam comprising a resin, The bead foam has one or more portions corresponding to feeder discharge marks during bead foam molding, The thinnest thickness of the portion corresponding to the feeder discharge mark is 5 mm or less. Bead foam.

5. The thickness of a portion of the bead foam is 60 mm or less. The bead foam according to claim 4.

6. having a pair of opposing surfaces, one of the pair of surfaces has a portion corresponding to a feeder discharge mark during bead foam molding, the other surface has a portion corresponding to the core vent mark formed during bead foam molding; When viewed from a perspective perpendicular to the one surface, a part or all of a portion corresponding to at least one core vent mark in the other surface is present within an area occupied by the feeder discharge mark. The bead foam according to claim 4 or 5.

7. It has a runner portion that is cut off when in use, The runner portion has a portion corresponding to a feeder discharge mark during molding of the bead foam. The bead foam according to claim 4 or 5.

8. 8. The bead foam according to claim 7, characterized in that: (A) or (B) below. (A) the runner portion is perpendicular to the plane of the bead foam; (B) the runner portion is in the plane of the bead foam.

9. 6. The bead foam according to claim 4, having vent holes on the feeder discharge marks formed during foam molding.

10. The flatness of the foamed beads at the part corresponding to the feeder discharge mark during the foamed bead molding (the cross section of the foamed beads is ２ The average value of ((maximum in-plane diameter - maximum thickness direction diameter) / maximum in-plane diameter) per The bead foam according to claim 4 or 5.

11. The number of foamed beads in the thickness direction of the foamed beads in the part corresponding to the feeder discharge mark (1 cm ２ the average number of foamed beads in the thickness direction per unit area is 1.2 or more and 15 or less; The bead foam according to claim 4 or 5.

12. The ratio of the density of the portion corresponding to the feeder discharge port trace during molding of the bead foam to the average density of the entire bead foam is 110 to 300%. The bead foam according to claim 4 or 5.

13. the ratio of the modulus of elasticity of the portion corresponding to the trace of the feeder discharge port during molding of the bead foam to the average modulus of elasticity of the entire bead foam is 120 to 600%; The bead foam according to claim 4 or 5.

14. A mold for bead expansion molding, characterized by the following (A) or (B): (A) The molding material filling space of the mold has a pair of opposing surfaces, The molding material filling space is connected to a feeder, One of the pair of surfaces has a discharge port of the feeder, the other face having a core vent; The thickness of the molding material filling space at the portion where the discharge port of the feeder is present is 5 mm or less, In a view perpendicular to the one surface, a part or all of at least one core vent in the other surface is present within an area occupied by the discharge port of the feeder; (B) the molding material filling space of the mold has a portion corresponding to a runner portion that is cut off when the bead foam molded by the mold is used; The portion corresponding to the runner portion has a feeder discharge mark, The thickness of the molding material filling space at the portion where the discharge port of the feeder is present is 5 mm or less.

15. The molding material filling space of the mold has a pair of opposing surfaces, The molding material filling space is connected to one or more feeders, One of the pair of surfaces has one or more discharge ports for the feeder, One or more of the feeders is a feeder as defined in claim 1. Mold for forming bead foam.

16. The mold for molding a bead foam according to claim 14 or 15, which has a vent hole near the discharge port of the feeder.

17. The following steps: Filling thermoplastic resin beads into a molding material filling space of a mold through one or more feeders; and The process includes a step of performing bead expansion molding on the thermoplastic resin beads filled in the molding material filling space of the mold to form a bead foam, A method for producing a bead foam, characterized by the following (A) or (B): (A) the molding material filling space of the mold has a pair of opposing surfaces, One of the pair of surfaces has a discharge port of the feeder, the other face having a core vent; The thickness of the molding material filling space at the portion where the discharge port of the feeder is present is 5 mm or less, In a view perpendicular to the one surface, a part or all of at least one core vent in the other surface is present within an area occupied by the discharge port of the feeder; (B) the molding material filling space of the mold has a portion corresponding to a runner portion that is cut off when the bead foam molded by the mold is used; the portion corresponding to the runner portion has a discharge port of the feeder, The thickness of the molding material filling space at the portion where the discharge port of the feeder is present is 5 mm or less.

18. The following steps: Filling thermoplastic resin beads into a molding material filling space of a mold through one or more feeders; and The process includes a step of performing bead expansion molding on the thermoplastic resin beads filled in the molding material filling space of the mold to form a bead foam, The molding material filling space of the mold has a pair of opposing surfaces, One of the pair of surfaces has one or more discharge ports for the feeder, The intersection of the inclined flow paths of the feeder is present in the molding material filling space. Manufacturing method.

19. The method for producing a bead foam according to claim 17 or 18, wherein the feeder has an air hole near the outlet thereof.