Thermoplastic resin foam particles, thermoplastic resin foam particle molded articles, foamed resin composites, methods for manufacturing thermoplastic resin foam particles, and methods for manufacturing thermoplastic resin foam particle molded articles

Abstract

This foamed thermoplastic resin particle comprises a thermoplastic resin, the thermoplastic resin including a polyester-based resin, a polyimide-based resin, and a phosphorus-based flame-retardant, wherein the content of the polyimide-based resin is 5-45% by mass based on the total mass of the thermoplastic resin, and the content of phosphorus is 0.15-1.00% by mass based on the total mass of the thermoplastic resin. The content of the polyimide-based resin is preferably 25-45% by mass.

Description

[Technical Field]

[0001] The present invention relates to thermoplastic resin foam particles, thermoplastic resin foam particle molded articles, foamed resin composites, methods for producing thermoplastic resin foam particles, and methods for producing thermoplastic resin foam particle molded articles. This application claims priority with respect to Japanese Patent Application No. 2022-094483, filed in Japan on June 10, 2022, and the contents of that application are incorporated herein by reference. [Background technology]

[0002] Molded articles of foamed particles containing thermoplastic resin (thermoplastic resin foamed particles) are lightweight and have excellent heat insulation, cushioning, and mechanical strength. For this reason, thermoplastic resin foamed particle molded articles (sometimes simply called "foamed particle molded articles") are being considered for application in automobiles, aircraft, railway vehicles, and the like. Among thermoplastic resins, polyester resins such as polyethylene terephthalate (PET) can be used to create foamed particle molded articles with excellent rigidity and heat resistance, and therefore, research into foamed particle molded articles using polyester resins is progressing.

[0003] One method for manufacturing foamed particle molded articles is in-mold foam molding. In-mold foam molding will be explained below. Thermoplastic resin foamed particles (sometimes simply called "foamed particles") are filled into the cavity of a mold. The foamed particles in the cavity are heated with a heating medium such as hot water or steam to foam them into secondary foamed particles, and the foaming pressure of the secondary foamed particles causes them to heat-fuse together to form a single, integrated foamed particle molded article of the desired shape.

[0004] The glass transition temperature (Tg) of polyester resins is lower than that of polystyrene resins. Therefore, foamed particle molded articles made from polyester resins become soft when heated (they have low heat resistance). Conventionally, to improve heat resistance, thermoplastic resin foamed particles and foamed particle molded articles containing both polyester resin and polyimide resin, with a single glass transition temperature (Tg), have been proposed (Patent Document 1).

[0005] In addition, for certain applications, foamed particle molded articles require flame retardancy. For example, Patent Document 2 proposes a thermoplastic resin foam particle molded article containing an amorphous polyphenylene ether resin and a flame retardant. Patent Document 3 proposes a polyester resin foam containing a crystalline polyester resin and a bromine flame retardant. Alternatively, for example, Patent Document 4 proposes a flame-retardant polyester resin foam containing a polyester resin and a polyarylate resin. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2022-57468 [Patent Document 2] International Publication No. 2011 / 019057 [Patent Document 3] Japanese Patent Publication No. 2006-249158 [Patent Document 4] Japanese Patent Publication No. 2000-63553 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] However, while the invention described in Patent Document 1 increases heat resistance, it does not consider flame retardancy. In addition, increasing the amount of polyimide resin to further increase heat resistance requires a special molding machine capable of increasing vapor pressure and performing in-mold foam molding. Therefore, when using a general-purpose molding machine, it is not possible to mold the foam particle molded body into the desired shape (low moldability). Although the invention described in Patent Document 2 is flame-retardant, it contains an amorphous resin, and therefore is prone to expansion or contraction when the temperature is increased by heating or other means. In other words, the invention described in Patent Document 2 has low dimensional stability when heated and poor heat resistance. While the invention described in Patent Document 3 improves flame retardancy using a bromine-based flame retardant, there is a need for greater consideration of the environment. The invention described in Patent Document 4 relates to a foamed sheet and does not consider its application to thermoplastic resin foamed particles and molded articles thereof.

[0008] Therefore, the present invention aims to provide thermoplastic resin foam particles that are excellent in flame retardancy and heat resistance, and also excellent in moldability of foamed particle molded articles. [Means for solving the problem]

[0009] Generally, unfoamed resins containing flame retardants exhibit excellent flame retardancy. However, foamed resins containing flame retardants have significantly lower flame retardancy compared to unfoamed resins containing flame retardants. Furthermore, foamed resins contain less resin per unit volume compared to unfoamed resins, thus conserving resources. However, because foamed resins contain less resin per unit volume, they are less likely to form a carbonized layer when burned, resulting in a longer burning time. Therefore, the flame retardancy of foamed resins is thought to decrease. In addition, foamed resins, compared to unfoamed resins, contain less resin per unit volume, making them more susceptible to softening due to combustion heat and prone to dripping during combustion. Furthermore, foamed resins containing crystalline resins experience a rapid decrease in viscosity when they melt during combustion. For these reasons, foamed resins are prone to dripping during combustion. Increasing the flame retardant content in foamed resin improves flame retardancy, but it also degrades its mechanical properties. In addition, because flame retardants have a plasticizing effect on resins, increasing the flame retardant content can lead to problems such as decreased heat resistance of the foamed resin and inhibition of foaming due to a decrease in extensional viscosity. Furthermore, as described in Patent Document 4, increasing the content of super engineering plastics such as polyarylate resin reduces the foaming properties of thermoplastic resin foam particles, and thus reduces the moldability of the foam particles. Thus, simply adding a flame retardant to foamed resin does not yield the desired physical properties. As a result of diligent research, the inventors of the present invention discovered that by setting the polyimide resin content within a specific range and the phosphorus-based flame retardant within a specific range, flame retardancy, heat resistance, and moldability can be improved, thus completing the present invention.

[0010] That is, the present invention has the following aspects. <1> Contains thermoplastic resin, The thermoplastic resin comprises a polyester resin, a polyimide resin, and a phosphorus-based flame retardant. The polyimide resin content is 5 to 45% by mass relative to the total mass of the thermoplastic resin. Thermoplastic resin foam particles having a phosphorus content of 0.15 to 1.00% by mass relative to the total mass of the thermoplastic resin. <2> The content of the polyimide resin is 25 to 45% by mass relative to the total mass of the thermoplastic resin. <1> The thermoplastic resin foam particles described. <3> The glass transition temperature (Tg) is 80-130°C. <1> or <2> Thermoplastic resin foam particles as described above.

[0011] <4> It consists of two or more thermoplastic resin foam particles that are heat-fused together. Contains thermoplastic resin, The thermoplastic resin comprises a polyester resin, a polyimide resin, and a phosphorus-based flame retardant. The polyimide resin content is 5 to 45% by mass relative to the total mass of the thermoplastic resin. A molded article of foamed thermoplastic resin particles, wherein the phosphorus content is 0.15 to 1.00% by mass relative to the total mass of the thermoplastic resin. <5> The flame retardancy, as measured according to the UL standard UL-94 vertical method (11mm vertical combustion test), is V-0, V-1, or V-2. <4> A molded article of thermoplastic resin foam particles as described above. <6> The content of the polyimide resin is 25 to 45% by mass relative to the total mass of the thermoplastic resin. <4> A molded article of thermoplastic resin foam particles as described above. <7> The flame retardancy, as measured according to the UL standard UL-94 vertical method (11mm vertical combustion test), is V-0 or V-1. <6> A molded article of thermoplastic resin foam particles as described above. <8> The glass transition temperature (Tg) is 80-130°C. <4> ~ <7> A thermoplastic resin foam particle molded article as described in any of the following. <8-1> The polyester resin is at least one selected from the group consisting of polyethylene terephthalate resin (PET), polybutylene terephthalate resin (PBT), polyethylene naphthalate resin (PEN), polyethylene furanoate resin (PEF), polybutylene naphthalate resin (PBN), polytrimethylene terephthalate resin (PTT), copolymers of terephthalic acid, ethylene glycol, and cyclohexanedimethanol, and mixtures thereof. <1> ~ <8> Thermoplastic resin foam particles or thermoplastic resin foam particle molded articles as described in any of the above. <8-2> The aforementioned polyester resin is polyethylene terephthalate resin. <1> ~ <8> Thermoplastic resin foam particles or thermoplastic resin foam particle molded articles as described in any of the above. <8-3> The aforementioned polyester resin is crystalline polyethylene terephthalate resin (C-PET). <1> ~ <8> Thermoplastic resin foam particles or thermoplastic resin foam particle molded articles as described in any of the above. <8-3> The polyester resin is at least one selected from the group consisting of petrochemical-derived polyester resins and plant-derived polyester resins (for example, polyethylene terephthalate resin, plant-derived polyethylene furanoate resin, and plant-derived polytrimethylene terephthalate resin). <1> ~ <8> Thermoplastic resin foam particles or thermoplastic resin foam particle molded articles as described in any of the above. <8-4> The polyimide resin is a compound represented by the following formula (3): <1> Thermoplastic resin foam particles or thermoplastic resin foam particle molded articles as described in any of <8-3>. [ka]

[0012] [(3) In equation (3), R is an aromatic group having carbon atoms with 6 to 42 carbon atoms, and R' is at least one divalent organic group selected from the group consisting of divalent aromatic groups with 6 to 30 carbon atoms, aliphatic groups with 2 to 30 carbon atoms, and alicyclic groups with 4 to 30 carbon atoms. p is the number representing the repeating unit.]

[0013] <8-5> The polyimide resin content is 25 to 40% by mass relative to the total mass of the thermoplastic resin. <1> Thermoplastic resin foam particles or thermoplastic resin foam particle molded articles as described in any of <8-4>. <8-6> The phosphorus-based flame retardant is at least one selected from the group consisting of phosphate compounds, polyphosphate compounds, red phosphorus, organophosphate ester compounds, phosphazene compounds, phosphonic acid compounds, phosphinic acid compounds, phosphine oxide compounds, phosphorane compounds, and phosphoramide compounds. <1> Thermoplastic resin foam particles or thermoplastic resin foam particle molded articles as described in any of <8-5>. <8-7> The thermoplastic resin foam particle or thermoplastic resin foam particle molded article according to <8-6>, wherein the phosphate compound is at least one selected from the group consisting of melamine phosphate, guanidine phosphate, ammonium phosphate, ammonium phosphate amidoammonium, and carbamate phosphate, and the polyphosphate compound is at least one selected from the group consisting of melamine polyphosphate, guanidine polyphosphate, ammonium polyphosphate, ammonium polyphosphate amidoammonium, and carbamate polyphosphate. <8-8> The phosphorus content is 0.25 to 0.80% by mass relative to the total mass of the thermoplastic resin. <1> Thermoplastic resin foam particles or thermoplastic resin foam particle molded articles as described in any of <8>7>.

[0014] <8-9> The content of the polyimide resin is 30 to 40% by mass relative to the total mass of the thermoplastic resin. The phosphorus content is 0.30 to 0.66% by mass relative to the total mass of the thermoplastic resin. The degree of crystallinity of the aforementioned thermoplastic resin foam particles is 3.3 to 6.3%. The glass transition temperature Tg is 91.2 to 94.5°C. <1> Thermoplastic resin foam particles or thermoplastic resin foam particle molded articles as described in any of the items in <8-8>. <8-10> The open-cell ratio of the aforementioned thermoplastic resin foam particles is 3.4 to 16%. <1> Thermoplastic resin foam particles or molded articles of thermoplastic resin foam particles as described in any of <8> or <9>.

[0015] <9> <4> A foamed resin composite comprising a thermoplastic resin foam particle molded body described in any of <8-10> and a fiber-reinforced resin layer provided on at least a portion of the surface of the thermoplastic resin foam particle molded body.

[0016] <10> The process includes a step of extruding and foaming a thermoplastic resin composition containing a thermoplastic resin and a foaming agent to obtain thermoplastic resin foam particles. The thermoplastic resin comprises a polyester resin, a polyimide resin, and a phosphorus-based flame retardant. The polyimide resin content is 5 to 45% by mass relative to the total mass of the thermoplastic resin. A method for producing foamed thermoplastic resin particles, wherein the phosphorus content is 0.15 to 1.00% by mass relative to the total mass of the thermoplastic resin. <11> The content of the polyimide resin is 25 to 45% by mass relative to the total mass of the thermoplastic resin. <10> A method for producing thermoplastic resin foam particles as described above.

[0017] <12> <10> or <11> A method for producing a molded article of thermoplastic resin foam particles, comprising: obtaining thermoplastic resin foam particles by the method for producing thermoplastic resin foam particles described above; filling the obtained thermoplastic resin foam particles into a mold cavity; heating the thermoplastic resin foam particles in the cavity to form secondary foam particles; and heat-fusing the secondary foam particles together to obtain a molded article of thermoplastic resin foam particles. <13> <4> A battery case or battery case comprising a thermoplastic resin foam particle molded body as described in any of <8>10>. [Effects of the Invention]

[0018] According to the thermoplastic resin foam particles of the present invention, the flame retardancy and heat resistance of the foam particle molded article can be improved, and the moldability can be enhanced. [Brief explanation of the drawing]

[0019] [Figure 1] This is a flowchart illustrating an example of the manufacturing process for plant-derived polyester resins. [Figure 2] This is a flowchart illustrating an example of the manufacturing process for plant-derived polyester resins. [Figure 3] This is a flowchart illustrating an example of the manufacturing process for plant-derived polyester resins. [Figure 4] This is a schematic side cross-sectional view showing an example of a manufacturing apparatus for thermoplastic resin foam particles according to the present invention. [Figure 5] This is a schematic front view showing an example of a manufacturing apparatus for thermoplastic resin foam particles according to the present invention. [Figure 6] This is a schematic front view showing an example of a manufacturing apparatus for thermoplastic resin foam particles according to the present invention. [Figure 7] This is a cross-sectional view of a foamed resin composite according to one embodiment of the present invention. [Modes for carrying out the invention]

[0020] In this paper, "~" represents a range that includes the values ​​at both ends as the lower and upper limits, respectively.

[0021] (Thermoplastic resin foam particles) The thermoplastic resin foam particles (foamed particles) of the present invention contain a thermoplastic resin. The foamed particles are particles obtained by granulating and foaming a thermoplastic resin composition (hereinafter sometimes simply referred to as "resin composition") which contains a thermoplastic resin and a foaming agent. Foamed particles are particulate foams. Foamed particles are used as raw materials for thermoplastic resin foamed particle molded articles (foamed particle molded articles) that are formed by so-called in-mold foaming.

[0022] <Thermoplastic resin> The thermoplastic resin of the foamed particles contains a polyester resin, a polyimide resin, and a phosphorus-based flame retardant. The foamed particles of the present invention, by containing both a polyester resin and a polyimide resin, enhance the heat resistance of the foamed particle molded article. In addition, the foamed particles of the present invention, by containing a phosphorus-based flame retardant, impart flame retardancy to the foamed particle molded article.

[0023] Polyester resin Examples of polyester resins include polyethylene terephthalate resin (PET), polybutylene terephthalate resin (PBT), polyethylene naphthalate resin (PEN), polyethylene furanoate resin (PEF), polybutylene naphthalate resin (PBN), polytrimethylene terephthalate resin (PTT), copolymers of terephthalic acid, ethylene glycol, and cyclohexanedimethanol, and mixtures thereof. Polyethylene terephthalate resin is preferred as the polyester resin, and crystalline polyethylene terephthalate resin (C-PET) is more preferred. C-PET is a polyester resin in which the acid component is terephthalic acid and the glycol component is ethylene glycol. The polyester resin may be a polyester resin derived from petrochemicals, a plant-derived polyester resin such as so-called bio-PET, or a mixture thereof. Examples of plant-derived polyester resins include polyethylene terephthalate resin, plant-derived polyethylene furanoate resin, and plant-derived polytrimethylene terephthalate resin. Furthermore, polyester resins can be made from recycled materials. These polyester resins may be used individually or in combination of two or more types.

[0024] The following describes plant-derived polyester resins. Plant-derived polyester resins are polymers derived from plant materials such as sugarcane and corn. "Derived from plant materials" refers to polymers synthesized or extracted from plant materials. Furthermore, for example, "derived from plant materials" refers to polymers formed by polymerizing monomers synthesized or extracted from plant materials. "Monomers synthesized or extracted from plant materials" includes monomers synthesized using compounds synthesized or extracted from plant materials as raw materials. Plant-derived polyester resins contain monomers that are "derived from plant materials."

[0025] This section will explain plant-derived polyester resins, using PET and PEF as examples.

[0026] The synthesis reaction of PET is shown in equation (1). PET is synthesized by the dehydration reaction of n moles of ethylene glycol and n moles of terephthalic acid (Benzen-1,4-dicarboxylic acid). The stoichiometric mass ratio in this synthesis reaction is ethylene glycol:terephthalic acid = 30:70 (mass ratio).

[0027] [ka]

[0028] [In equation (1), n ​​is the stoichiometric coefficient (degree of polymerization), and is a number between 250 and 1100.]

[0029] Ethylene glycol is produced industrially by oxidizing and hydrating ethylene. Similarly, terephthalic acid is produced industrially by oxidizing paraxylene. Here, as shown in Figure 1, when ethylene is obtained by the dehydration reaction of plant-derived ethanol (bioethanol), and PET is synthesized from this ethylene (ethylene glycol derived from bioethanol) and terephthalic acid derived from petrochemicals, the PET produced is 30% by mass of plant-derived PET. Furthermore, as shown in Figure 2, when paraxylene is obtained by the dehydration reaction of plant-derived isobutanol (bioisobutanol), and PET is synthesized from terephthalic acid synthesized from this paraxylene and ethylene glycol derived from bioethanol, the PET produced is 100% plant-derived by mass.

[0030] The synthesis reaction of PEF is shown in equation (2). PEF is synthesized by the dehydration reaction of n moles of ethylene glycol and n moles of furandicarboxylic acid (2,5-Furandicarboxylic acid).

[0031] [ka]

[0032] [In equation (2), n is the stoichiometric coefficient (degree of polymerization), and is a number between 250 and 1100.]

[0033] Frangicarboxylic acid (FDCA) can be obtained, for example, by dehydrating plant-derived fructose or glucose to obtain hydroxymethylfurfural (HMF), and then oxidizing HMF. As shown in Figure 3, when both FDCA and ethylene glycol are plant-derived, the resulting PEF is 100% plant-derived by mass.

[0034] The ratio of polyester resin to the total mass of thermoplastic resin contained in the foamed particles is preferably 55 to 95% by mass, more preferably 55 to 75% by mass, even more preferably 60 to 75% by mass, and particularly preferably 60 to 70% by mass. If the polyester resin content is above the lower limit, moldability can be improved. If the polyester resin content is below the upper limit, heat resistance can be further improved.

[0035] ≪Polyimide resin≫ As polyimide resins, polymers containing cyclic imide groups as repeating units are preferred, and polymers having a melt-molded article are more preferably exemplified. Examples include polyetherimides described in U.S. Patent No. 4,141,927, Japanese Patent Publication No. 2,622,678, Japanese Patent Publication No. 2606,912, Japanese Patent Publication No. 2606,914, Japanese Patent Publication No. 2596,565, Japanese Patent Publication No. 2596,566, and Japanese Patent Publication No. 2598,478, as well as polymers described in Japanese Patent Publication No. 2598,536, Japanese Patent Publication No. 2599,171, Japanese Patent Publication No. 9-48852, Japanese Patent Publication No. 2565,556, Japanese Patent Publication No. 2564,636, Japanese Patent Publication No. 2564,637, Japanese Patent Publication No. 2563,548, Japanese Patent Publication No. 2563,547, Japanese Patent Publication No. 2558,341, Japanese Patent Publication No. 2558,339, and Japanese Patent Publication No. 2834,580. The polyimide resin main chain may contain structural units other than cyclic imides, as long as the effects of the present invention are not impaired. Examples of structural units other than cyclic imides include aromatic, aliphatic, alicyclic, alicyclic ester units, and oxycarbonyl units. Furthermore, the polyimide resin may be made from recycled materials. The polyimide resin may also be a plant-derived resin such as biopolyimide. These polyimide resins may be used individually or in combination of two or more types.

[0036] For example, the polyimide resin is preferably a compound represented by the following formula (3).

[0037] [ka]

[0038] [(3) In equation (3), R is an aromatic group having carbon atoms with 6 to 42 carbon atoms, and R' is at least one divalent organic group selected from the group consisting of divalent aromatic groups with 6 to 30 carbon atoms, aliphatic groups with 2 to 30 carbon atoms, and alicyclic groups with 4 to 30 carbon atoms. p is the number representing the repeating unit.]

[0039] As for the polyimide resin, a polyetherimide resin having structural units with ether bonds is preferred from the viewpoint of improving compatibility with polyester resins.

[0040] Polyimide resins can be prepared by conventionally known manufacturing methods. For example, they can be obtained by dehydration condensation of one or more compounds selected from the group consisting of aliphatic primary diamines and aromatic primary diamines, which are raw materials that can derive R in formula (3), with either tetracarboxylic acid and / or its acid anhydride, which are raw materials that can derive R' in formula (3). Specifically, examples of methods for producing polyimide resins include obtaining polyamic acid and then performing heat cyclization. Alternatively, examples include chemical cyclization using an acid anhydride and a chemical cyclizing agent such as pyridine or carbodiimide, or polymerization by heating the tetracarboxylic anhydride and a diisocyanate that can derive R' to decarboxylate and perform polymerization.

[0041] Examples of tetracarboxylic acids include pyromellitic acid, 1,2,3,4-benzenetetracarboxylic acid, 3,3',4,4'-biphenyltetracarboxylic acid, 2,2',3,3'-biphenyltetracarboxylic acid, 3,3',4,4'-benzophenonetetracarboxylic acid, 2,2',3,3'-benzophenonetetracarboxylic acid, bis(2,3-dicarboxyphenyl)methane, bis(3,4-dicarboxyphenyl)methane, 1,1'-bis(2,3-dicarboxyphenyl)ethane, and 2,2'-bis(3,4-dicarboxyphenyl). Examples include propane, 2,2'-bis(2,3-dicarboxyphenyl)propane, bis(3,4-dicarboxyphenyl) ether, bis(2,3-dicarboxyphenyl) ether, bis(3,4-dicarboxyphenyl) sulfone, bis(2,3-dicarboxyphenyl) sulfone, 2,3,6,7-naphthalenetetracarboxylic acid, 1,4,5,8-naphthalenetetracarboxylic acid, 1,2,5,6-naphthalenetetracarboxylic acid, 2,2'-bis[(2,3-dicarboxyphenoxy)phenyl]propane and its acid anhydrides.

[0042] Examples of diamines include benzidine, diaminodiphenylmethane, diaminodiphenylethane, diaminodiphenylpropane, diaminodiphenylbutane, diaminodiphenyl ether, diaminodiphenyl sulfone, diaminodiphenylbenzophenone, o,m,p-phenylenediamine, tolylenediamine, xylenediamine, and aromatic primary diamines having hydrocarbon groups of these aromatic primary diamines as structural units, ethylenediamine, 1,2-propanediamine, 1,3-propanediamine, 2,2-dimethyl-1,3-propanediamine, 1,6-hexamethylenediamine, 1,8 Examples include octamethylenediamine, 1,9-nonameethylenediamine, 1,10-decamethylenediamine, 1,11-undecamethylenediamine, 1,12-dodecamethylenediamine, 2,2,4-trimethylhexamethylenediamine, 2,4,4-trimethylhexamethylenediamine, 1,3-cyclohexanediamine, 1,4-cyclohexanediamine, 1,4-cyclohexanedimethylamine, 2-methyl-1,3-cyclohexanediamine, isophoronediamine, and the aliphatic forms thereof, as well as aliphatic and alicyclic primary diamines having hydrocarbon groups of alicyclic primary diamines as structural units.

[0043] The polyimide resin content relative to the total mass of thermoplastic resin contained in the foamed particles is 5 to 45% by mass, preferably 25 to 45% by mass, and more preferably 25 to 40% by mass. If the polyimide resin content is above the lower limit, the heat resistance and flame retardancy can be further enhanced. If the polyimide resin content is below the upper limit, the moldability can be further enhanced.

[0044] [Method for measuring the content ratio of polyimide resins] When it is necessary to determine the proportion of polyimide resin relative to the total mass of thermoplastic resin contained in foamed particles and the foamed particle molded product described below, the proportion of polyimide resin can be measured by the following method. For example, the foamed particles and the foamed particle molded product can be sliced ​​to prepare thin samples (e.g., samples with a thickness of 0.2 mm), and the proportion of polyimide resin can be measured in these samples. Below is an example of how to measure the proportion of polyimide resin relative to the total mass of a mixed resin of polyester resin and polyimide resin.

[0045] A 0.2 mm thick sample is cut from the foamed particles and the foamed particle molded body, and this is used as the measurement sample. Infrared spectroscopy analysis of the surface of the measurement sample is performed under the following conditions to obtain the infrared absorption spectrum. Measurement equipment: Thermo SCIENTIFIC Co., Ltd. "Nicolet iS10" Fourier transform infrared spectrophotometer and Thermo SCIENTIFIC Co., Ltd. single-reflection horizontal ATR Smart-iTR. ATR Crystal: Diamond-attached KRS-5 (angle = 42°). ·Measurement method: Single reflection ATR method. ·Measurement wavenumber range: 4000cm -1 ~675cm -1 . • Wavenumber dependence of measurement depth: Uncorrected • Detectors: Deuterated triglycine sulfate (DTGS) detector and KBr beam splitter. ·Resolution: 4cm -1 . • Number of cumulative measurements: 16 (same for background measurements).

[0046] From the obtained infrared absorption spectrum chart, the peak heights of D1410 and D1778 are determined, and the polyimide resin content is calculated using the following equation (p) obtained from a calibration curve created using standard samples. Polyimide resin content (mass%) = 100 - {1.987 × R 2 +19.589 × R + 22.44} ···(p) R=D1410 / D1778

[0047] D1410 means the maximum value of the absorbance difference (measured absorbance - absorbance of the baseline) from the baseline in the infrared absorption spectrum curve in the region of 1410 cm -1 ±5 cm -1 derived from the polyester resin. The baseline is a straight line connecting the lowest absorption position at a wavenumber of 1400 cm -1 ±5 cm -1 and the lowest absorption position at a wavenumber of 1420 cm -1 ±5 cm -1 in the infrared absorption spectrum curve. Also, D1778 means the maximum value of the absorbance difference (measured absorbance - absorbance of the baseline) from the baseline in the infrared absorption spectrum curve in the region of 1778 cm -1 ±5 cm -1 derived from the polyimide resin. The baseline is a straight line connecting the lowest absorption position at a wavenumber of 1760 cm -1 ±5 cm -1 and the lowest absorption position at a wavenumber of 1800 cm -1 ±5 cm -1 in the infrared absorption spectrum curve. The standard sample is prepared as follows.

[0048] [Preparation of Standard Sample] First, a mixture is prepared by mixing polyester resin (PET: manufactured by Far Eastern New Century Co., Ltd., product name "CH-653"), polyimide resin (polyetherimide (PEI) resin: manufactured by SABIC Innovative Plastics, product name "Ultem1000"), and pyromellitic anhydride (PMDA) according to the formulation shown in Table 1. This mixture is fed into a Laboplastmill twin-screw extruder (manufactured by Toyo Seiki Seisakusho Co., Ltd., model: 2D15W, bore diameter 15 mm, L / D=17) and melt-kneaded at 350°C to form a resin composition. This resin composition is extruded from a nozzle mold (diameter 3.0 mm) attached to the front end of the Laboplastmill twin-screw extruder. The extruded resin composition is immediately cooled in a cooling water bath. Then, after thoroughly draining the cooled strand-like resin composition, standard samples (A-I) are prepared by cutting it into small granules approximately 2 mm long and 3 mm in diameter using a pelletizer. The compositions of the standard samples (A-I) are shown in Table 1.

[0049] [Table 1]

[0050] [Creating a calibration curve] The calibration curve described above is created as follows. Infrared spectroscopy was performed on the surface of the aforementioned standard samples (A to I) under the following conditions to obtain infrared absorption spectra. • Measurement equipment: Thermo SCIENTIFIC Co., Ltd. "Nicolet iS10" Fourier transform infrared spectrophotometer and Thermo SCIENTIFIC Co., Ltd. Smart-iTR single-reflection horizontal ATR. ATR Crystal: Diamond-attached KRS-5 (angle = 42°). ·Measurement method: Single reflection ATR method. ·Measurement wavenumber range: 4000cm -1 ~675cm -1 . • Wavenumber dependence of measurement depth: Uncorrected • Detectors: Deuterated triglycine sulfate (DTGS) detector and KBr beam splitter. ·Resolution: 4cm -1 . • Number of cumulative measurements: 16 (same for background measurements). • Number of measurements: 10.

[0051] From the infrared absorption spectrum charts obtained in each measurement, data processing is performed in the same manner as when determining the polyimide resin content, and the peak heights of D1410 and D1778 are determined, and the absorbance ratio (R=D1410 / D1778) is calculated. The blending ratio of polyester resin to the absorbance ratio of each standard sample (A~I) is plotted, and the logarithmic approximation formula in the plot is used as the calibration curve.

[0052] In the foamed particles, the mass ratio of polyester resin to polyimide resin is preferably 55:45 to 95:5, more preferably 60:40 to 85:15, and even more preferably 60:40 to 75:25.

[0053] The thermoplastic resin contained in the foamed particles may contain recycled materials. Recycled materials may be contained in either the polyester resin or the polyimide resin, or in both the polyester resin and the polyimide resin. Part or all of the polyester resin may be recycled polyester resin, or part or all of the polyimide resin may be recycled polyimide resin. Examples of recycled materials include the following: 1) Recovered pellets obtained by crushing foamed material such as foamed particles or molded foamed particle bodies, remelting the flake-shaped resin obtained in an extruder, extruding it in a strand shape from a nozzle mold, cooling it, and then pelletizing it. 2) Recycled PET obtained by crushing PET bottles to obtain flake-like resin, remelting it in an extruder, extruding it in strand form through a nozzle mold, cooling it, and then pelletizing it.

[0054] <Phosphorus-based flame retardants> Examples of phosphorus-based flame retardants include phosphate compounds, polyphosphate compounds, red phosphorus, organophosphate ester compounds, phosphazene compounds, phosphonic acid compounds, phosphinic acid compounds, phosphine oxide compounds, phosphorane compounds, and phosphoramide compounds. Examples of phosphate compounds include melamine phosphate, guanidine phosphate, ammonium phosphate, ammonium phosphate amidoammonium, and carbamate phosphate. Examples of polyphosphate compounds include melamine polyphosphate, guanidine polyphosphate, ammonium polyphosphate, ammonium polyphosphate amidoammonium, and carbamate polyphosphate. Phosphorus-based flame retardants can be selected from a variety of phosphorus-containing compounds, including low molecular weight compounds and polymer-type compounds with repeating units. These phosphorus-based flame retardants are included in the mass excluding the total amount of ash and blowing agent. For this reason, in the present invention, the phosphorus-based flame retardant is treated as part of the thermoplastic resin. The phosphorus-based flame retardant may be incorporated into the resin composition alone, or it may be incorporated into the resin composition as a masterbatch (MB). The phosphorus-based flame retardants described above may be used alone or in combination of two or more. These phosphorus-based flame retardants may also be used in combination with other flame retardants such as halogen-based flame retardants, nitrogen-based flame retardants, silicon-based flame retardants, and inorganic flame retardants, to the extent that the effects of the present invention are not impaired.

[0055] The phosphorus-based flame retardant content is preferably 0.15 to 1.00% by mass, more preferably 0.25 to 0.90% by mass, and even more preferably 0.25 to 0.80% by mass, as the phosphorus content (phosphorus element content) relative to the total mass of the thermoplastic resin. If the phosphorus content is above the lower limit, flame retardancy can be improved. If the phosphorus content is below the upper limit, moldability can be improved.

[0056] <<Other resins>> The foamed particles are substantially free of thermosetting resin. "Substantially free" means either completely free or containing only a small amount that does not affect the quality of the foamed particles. The thermosetting resin content in the foamed particles is preferably 5.0% by mass or less, more preferably 2.0% by mass or less, even more preferably 1.0% by mass or less, and most preferably 0% by mass, per 100 parts by mass of thermoplastic resin.

[0057] The thermoplastic resin may include thermoplastic resins other than polyester resins and polyimide resins (other thermoplastic resins). Examples of other thermoplastic resins include polyethylene, polyolefin resins such as polypropylene, polystyrene resins, polyphenylene ether resins, polyamide resins, polycarbonate resins, polyarylate resins, polyphenyl sulfone resins, polysulfone resins, and polyethersulfone resins.

[0058] The total ratio of polyester resin and polyimide resin to the total mass of thermoplastic resin is preferably 90% by mass or more, more preferably 95% by mass or more, even more preferably 98% by mass or more, and particularly preferably 99% by mass or more. If the total ratio of polyester resin and polyimide resin is above the above lower limit, the heat resistance strength of the foamed particles can be further increased.

[0059] <Foaming agent> As a blowing agent, known blowing agents can be used. Blowing agents can be broadly classified into physical blowing agents and chemical blowing agents. Of these, physical blowing agents are preferred. Examples of physical blowing agents include saturated aliphatic hydrocarbons such as propane, n-butane, isobutane, n-pentane, isopentane, and hexane; ethers such as dimethyl ether; chlorofluorocarbons such as methyl chloride, 1,1,1,2-tetrafluoroethane, 1,1-difluoroethane, and monochlorodifluoromethane; carbon dioxide; and nitrogen. Dimethyl ether, propane, n-butane, isobutane, carbon dioxide, and nitrogen are preferred. These blowing agents may be used individually or in combination of two or more.

[0060] The amount of foaming agent is not particularly limited, but is preferably, for example, 0.10 to 12 parts by mass per 100 parts by mass of thermoplastic resin.

[0061] <Optional ingredients> The foamed particles of this embodiment may contain other components (optional components) besides the thermoplastic resin and foaming agent. Optional components include foam regulators, stabilizers, UV absorbers, colorants, antioxidants, crystallization accelerators, lubricants, crosslinking agents, surfactants, shrinkage inhibitors, flame retardants, and degradation inhibitors.

[0062] Examples of crosslinking agents include dianhydrides such as pyromellitic anhydride, polyfunctional epoxy compounds, oxazoline compounds, and oxazine compounds. By incorporating a crosslinking agent into the resin composition, foaming is suppressed and the open-cell ratio can be further reduced. The crosslinking agent content is preferably, for example, 0.080 to 0.80 parts by mass, more preferably 0.15 to 0.50 parts by mass, even more preferably 0.20 to 0.45 parts by mass, and particularly preferably 0.25 to 0.40 parts by mass, per 100 parts by mass of resin. If the crosslinking agent content is above the lower limit, the average molecular weight Mz of the foamed particles can be increased, thereby further improving moldability. If the crosslinking agent content is below the upper limit, the foamed particles will foam well during in-mold foaming, and the foamed particles will heat-fuse well with each other, thereby further improving moldability.

[0063] Foam regulators are, for example, mixtures of inorganic powders such as talc and silica. These foam regulators increase the percentage of closed cells in foamed particles, making it easier to form foamed particles. The content of the bubble regulator is preferably, for example, 0.20 to 5.0 parts by mass per 100 parts by mass of thermoplastic resin.

[0064] Examples of stabilizers include calcium-zinc-based heat stabilizers, tin-based heat stabilizers, and lead-based heat stabilizers. The stabilizer content is preferably, for example, 1.0 part by mass or less per 100 parts by mass of thermoplastic resin.

[0065] Examples of UV absorbers include cesium oxide-based UV absorbers and titanium dioxide-based UV absorbers. The amount of ultraviolet absorber is preferably, for example, 1.0 part by mass or less per 100 parts by mass of thermoplastic resin.

[0066] Antioxidants include, for example, cerium oxide, cerium oxide / zirconia solid solution, cerium hydroxide, carbon, carbon nanotubes, titanium dioxide, and fullerenes. The antioxidant content is preferably, for example, 1.0 part by mass or less per 100 parts by mass of thermoplastic resin.

[0067] Examples of colorants include titanium dioxide, carbon black, titanium yellow, iron oxide, ultramarine, cobalt blue, calcined pigments, metallic pigments, mica, pearl pigments, zinc oxide, precipitated silica, and cadmium red. When using the foamed particles of this embodiment in food containers, it is preferable to select a product registered with the Hygiene Council from among the above-mentioned colorants. The colorant content is preferably, for example, 2.0 parts by mass or less per 100 parts by mass of thermoplastic resin.

[0068] Crystallization accelerators include, for example, silicates, carbon, and metal oxides. Examples of silicates include talc, which is hydrated magnesium silicate. Examples of carbon include carbon black, carbon nanofibers, carbon nanotubes, carbon nanohorns, activated carbon, graphite, graphene, coke, mesoporous carbon, glassy carbon, hard carbon, and soft carbon. Examples of carbon black include furnace black, acetylene black, Ketjen black, and thermal black. Examples of metal oxides include zinc oxide and titanium oxide. The content of the crystallization accelerator is preferably, for example, 3.0 parts by mass or less per 100 parts by mass of the thermoplastic resin.

[0069] The above-mentioned optional components may be used individually or in combination of two or more. The total amount of optional components contained in the foamed particles is preferably 0.10 to 5.0 parts by mass, and more preferably 0.50 to 3.0 parts by mass, relative to the total mass of the foamed particles.

[0070] <Physical properties> The foamed particles exhibit a single glass transition temperature (Tg). This single Tg is achieved through the compatibility of the polyester resin and the polyimide resin. Because the foamed particles have a single glass transition temperature (Tg), it is higher than the glass transition temperature (Tg) of the polyester resin, resulting in increased heat resistance of the foamed particle molded article. Furthermore, "single glass transition temperature" means that, in the differential scanning calorimetry (DSC) chart at a heating rate of 10°C / min, the glass transition temperature Tg at a temperature lower than the crystallization peak observed during the second heating process can be recognized as single. However, if no crystallization peak is observed during the second heating process, it means that the glass transition temperature Tg can be recognized as single within the temperature range of the second heating process (30 to 300°C). The glass transition temperature Tg for foamed particles is preferably, for example, 80 to 130°C, more preferably 80 to 125°C, even more preferably 80 to 120°C, and particularly preferably 80 to 100°C. If Tg is above the lower limit, the heat resistance strength and heating dimensional stability of the foamed particle molded article can be further improved. If Tg is below the upper limit, the molding cycle can be shortened to increase productivity and improve moldability. The glass transition temperature (Tg) in foamed particles is determined by differential scanning calorimetry at a heating rate of 10°C / min. Furthermore, the glass transition temperature (Tg) of foamed particles can be considered identical to the glass transition temperature (Tg) of the thermoplastic resin constituting the foamed particles.

[0071] The absolute value of the difference between the amount of heat absorbed and the amount of heat released in the foamed particles (endothermic-exothermic difference) is preferably 3 to 35 J / g, more preferably 5 to 25 J / g, and even more preferably 7 to 15 J / g. If the endothermic-exothermic difference is above the lower limit, the degree of crystallinity increases, and the heat resistance strength and heating dimensional stability of the foamed particle molded body can be further improved. If the endothermic-exothermic difference is below the upper limit, the degree of crystallinity does not increase too much, and excellent secondary foaming and heat fusion properties are exhibited, improving moldability and mechanical strength. The endothermic-exothermic difference is determined by differential scanning calorimetry of the heat flux at a heating rate of 10°C / min and is the difference between the amount of heat absorbed and the amount of heat released. Furthermore, the endothermic and exothermic difference in foamed particles can be considered identical to the endothermic and exothermic difference of the thermoplastic resin constituting the foamed particles.

[0072] The size of the foam particles is selected appropriately according to the application, and the average particle diameter of the group of foam particles is, for example, 0.50 to 5.0 mm. The average particle size of a group of foamed particles is expressed as a value represented by D50. Specifically, a rotary tap type sieve shaker (manufactured by Iida Seisakusho Co., Ltd.) was used to shake JIS standard sieves with mesh openings of 26.5 mm, 22.4 mm, 19.0 mm, 16.0 mm, 13.2 mm, 11.20 mm, 9.50 mm, 8.80 mm, 6.70 mm, 5.66 mm, 4.76 mm, 4.00 mm, 3.35 mm, 2.80 mm, 2.36 mm, 2.00 mm, 1.70 mm, 1.40 mm, 1.18 mm, 1.00 mm, 0.85 mm, 0.71 mm, 0.60 mm, 0.50 mm, 0.425 mm, 0.355 mm, 0.300 mm, 0.250 mm, 0.212 mm, and 0.180 mm. Approximately 25g of the sample was classified for 10 minutes using Z8801-1:2006, and the weight of the sample on the sieve was measured. A cumulative weight distribution curve was created from the obtained results, and the particle size at which the cumulative weight reached 50% (median diameter) was defined as the average particle size.

[0073] The open-cell ratio of the foamed particles is preferably 20% or less, more preferably 18% or less, and even more preferably 16% or less. When the open-cell ratio of the foamed particles is below the above upper limit, the secondary foaming properties of the foamed particles are further enhanced, and the moldability and mechanical strength can be further improved. The open-cell ratio of the foamed particles can be determined by the method described in JIS K7138:2006 "Rigid foamed plastics - Method for determining open-cell ratio and closed-cell ratio".

[0074] The bulk density of the foamed particles is, for example, 0.027 to 0.675 g / cm³. 3 Preferably, 0.045~0.45 g / cm³ 3 More preferably, 0.0675~0.27 g / cm³ 3 This is even more preferable. If the bulk density is above the lower limit, the cushioning force of the foamed particle molded body can be increased. If the bulk density is below the upper limit, the mechanical strength of the foamed particle molded body can be increased.

[0075] The bulk expansion ratio of the foamed particles is preferably 2 to 50 times, more preferably 3 to 30 times, and even more preferably 5 to 20 times. If the bulk expansion ratio is above the lower limit, the amount of resin per unit volume can be further reduced, and the cushioning force can be increased. If the bulk expansion ratio is below the upper limit, the mechanical strength can be increased.

[0076] The average bubble diameter of the foamed particles is preferably, for example, 5 to 500 μm, more preferably 10 to 400 μm, and even more preferably 20 to 300 μm. If the average bubble diameter is above the lower limit, the buffering capacity can be increased. If the average bubble diameter is below the upper limit, the mechanical strength can be increased. The average bubble diameter can be measured in accordance with the test method of ASTM D3576-77.

[0077] For foamed particles, the temperature at which the loss tangent tanδ is maximized in solid viscoelasticity measurements at a heating rate of 5°C / min and a frequency of 1 Hz is preferably 120 to 230°C, more preferably 130 to 225°C, and even more preferably 150 to 220°C. If the temperature at which the loss tangent tanδ is maximized is above the lower limit, the temperature at which the foamed particle molded body softens will be higher, and the heat resistance strength of the foamed particle molded body can be further increased. If the temperature at which the loss tangent tanδ is maximized is below the upper limit, the temperature at which the foamed particle molded body softens will not be excessively high, and the moldability can be further improved. The temperature at which the loss tangent tanδ of foamed particles is maximized can be determined by molding a foamed particle molded body and measuring the solid viscoelasticity of this foamed particle molded body.

[0078] The average molecular weight Mz of the foamed particles is 2.5 × 10⁻⁶. 5 ~5.0×10 5 And, 2.9 × 10 5 ~5.0×10 5 Preferably, 3.2 × 10 5 ~5.0×10 5 This is more preferable. If the average molecular weight Mz of the foamed particles is above the lower limit, the open-cell ratio of the foamed particles can be suppressed, improving moldability. If the average molecular weight Mz of the foamed particles is below the upper limit, in in-mold foam molding, the foamed particles foam well and the foamed particles heat-fuse well with each other, improving moldability.

[0079] The number-average molecular weight Mn of the foam particles is 0.10 × 10⁻⁶. 5 ~0.30 × 10 5 Preferably, 0.15 × 10 5 ~0.25 × 10 5 More preferably, 0.18 × 10 5 ~0.23 × 10 5 That is even more preferable. If the number-average molecular weight Mn of the foamed particles is above the lower limit, impact resistance can be improved. If the number-average molecular weight Mn of the foamed particles is below the upper limit, moldability can be further improved.

[0080] The mass-average molecular weight Mw of the foamed particles is 0.50 × 10⁻⁶. 5 ~2.0×105 Preferably, 0.70 × 10 5 ~1.5×10 5 More preferably, 0.80 × 10 5 ~1.2 × 10 5 That is even more preferable. If the mass-average molecular weight Mw of the foamed particles is above the lower limit, impact resistance can be improved. If the mass-average molecular weight Mw of the foamed particles is below the upper limit, moldability can be further improved.

[0081] The molecular weight distribution of the foamed particles, expressed as Mw / Mn, is preferably 3.0 to 7.0, more preferably 3.5 to 6.5, and even more preferably 4.0 to 6.0. If the molecular weight distribution of the foamed particles is above the lower limit, the impact resistance can be further improved. If the molecular weight distribution of the foamed particles is below the upper limit, the moldability can be further improved.

[0082] The number-average molecular weight Mn, mass-average molecular weight Mw, and Z-average molecular weight Mz of the foamed particles are adjusted by the combination of the type and amount of raw material polyester resin and raw material polyimide resin, as well as the type and amount of crosslinking agent, as described later. Furthermore, the number-average molecular weight Mn, mass-average molecular weight Mw, and Z-average molecular weight Mz of the foamed particles can be considered identical to the number-average molecular weight Mn, mass-average molecular weight Mw, and Z-average molecular weight Mz of the thermoplastic resin constituting the foamed particles.

[0083] [Methods for measuring number-average molecular weight Mn, mass-average molecular weight Mw, and Z-average molecular weight Mz] The number-average molecular weight Mn, mass-average molecular weight Mw, and Z-average molecular weight Mz can be measured by the following methods. Take 5 mg of the sample from the target material, add 0.5 mL of hexafluoroisopropanol (HFIP) and 0.5 mL of chloroform in that order, and shake gently by hand. Let it stand for an immersion time of 6 ± 1.0 hr. After confirming that the sample is completely dissolved, dilute it with chloroform to 10 mL and mix by shaking gently by hand. Then, filter it using a non-aqueous 0.45 μm chromatographic disk manufactured by GL Sciences Co., Ltd. or a non-aqueous 0.45 μm syringe filter manufactured by Shimadzu GLC Co., Ltd. to obtain the measurement sample. Measure the measurement sample using a chromatograph under the following measurement conditions, and determine the number-average molecular weight Mn, mass-average molecular weight Mw, and Z-average molecular weight Mz of the sample from a pre-prepared standard polystyrene calibration curve.

[0084] [Measuring device] • Measuring device: Tosoh Corporation, "HLC-8320GPC EcoSEC," gel permeation chromatograph (with built-in RI detector and UV detector). [GPC measurement conditions] ·column <Sample side> Guard column = TSK guardcolumn HXL-H (6.0mm x 4.0cm) manufactured by Tosoh Corporation x 1. Measurement column = TSKgel GMHXL (7.8mm I.D. × 30cm) manufactured by Tosoh Corporation × 2 in series. <Reference side> Two resistor tubes (0.1mm inner diameter x 2m) in series. Column temperature = 40°C. Mobile phase = chloroform. <Mobile phase flow rate> Sample pump = 1.0 mL / min. Reference pump = 0.5 mL / min. Detector = UV detector (254nm). Injection volume = 15 μL. Measurement time = 25 minutes. Sampling pitch = 500ms.

[0085] [Standard polystyrene sample for calibration curve] Standard polystyrene samples for the calibration curve were selected from Showa Denko K.K.'s product names "STANDARD SM-105" and "STANDARD SH-75," with mass-average molecular weights (Mw) of 5,620,000, 3,120,000, 1,250,000, 442,000, 151,000, 53,500, 17,000, 7,660, 2,900, and 1,320. The standard polystyrenes for the calibration curve described above were grouped into A (5,620,000, 1,250,000, 151,000, 17,000, 2,900) and B (3,120,000, 442,000, 53,500, 7,660, 1,320). After weighing A (2 mg, 3 mg, 4 mg, 4 mg, 4 mg), they were dissolved in 30 mL of chloroform. After weighing B (3 mg, 4 mg, 4 mg, 4 mg, 4 mg), they were dissolved in 30 mL of chloroform. The standard polystyrene calibration curve was obtained by injecting 50 μL of each A and B solution and creating a calibration curve (cubic equation) from the retention time obtained after measurement. The number average molecular weight Mn, mass average molecular weight Mw, and Z average molecular weight Mz were calculated using this calibration curve.

[0086] The degree of crystallinity of the foamed particles is preferably 3.0 to 10%, more preferably 3.0 to 9.0%, and even more preferably 3.0 to 7.0%. If the degree of crystallinity of the foamed particles is above the lower limit, the heat resistance is further increased. If the degree of crystallinity of the foamed particles is below the upper limit, secondary foaming occurs well during in-mold foam molding, the foamed particles are more strongly heat-fused together, and the mechanical strength of the foamed particle molded body is further increased. The degree of crystallinity can be adjusted by a combination of the type of crosslinking agent, the amount added, and the temperature during the production of the foamed particles.

[0087] <Manufacturing method> Methods for producing foamed particles according to the present invention include a method of extruding a resin composition containing a thermoplastic resin and a foaming agent, foaming it, and obtaining foamed particles; a method of extruding a thermoplastic resin to obtain resin particles, impregnating the obtained resin particles with a foaming agent to make foamable particles, and heating the foamable particles to make foamed particles. More specific methods for manufacturing foamed particles include, for example, the following methods. 1) A method for obtaining foamed particles by supplying a thermoplastic resin and a foaming agent to an extruder, melting and kneading them, extruding the molten resin composition into the air through a die hole at the tip of the extruder to cause foaming, cutting the extruded foamed spherical particles simultaneously, and dropping the cut foamed spherical particles into water to cool them. 2) A method for supplying a thermoplastic resin and a foaming agent to an extruder and melting and kneading them, extruding the molten resin composition into water through a die hole at the tip of the extruder to foam and cool it, and simultaneously cutting the extruded, foamed, and cooled material to obtain cut foamed spherical foamed particles. 3) A method for obtaining foamed particles by supplying a thermoplastic resin and a foaming agent to an extruder, melting and kneading them, extruding the molten resin composition into water through a die hole at the tip of the extruder to cool, cutting the material while extruding and cooling, obtaining cut spherical foamed particles, and then heating the foamed particles. 4) A method in which a thermoplastic resin is supplied to an extruder and melted and kneaded, the molten thermoplastic resin is extruded into the air through a die hole at the tip of the extruder and cut at the same time as it is extruded, the cut spherical resin particles are dropped into water to cool and obtain resin particles, a foaming agent is impregnated into the resin particles to obtain foamed particles, and the foamed particles are heated to obtain foamed particles. 5) A method in which a thermoplastic resin is supplied to an extruder and melted and kneaded, the molten thermoplastic resin is extruded into water through a die hole at the tip of the extruder to cool, and while being extruded and cooled, it is cut to obtain cut spherical resin particles, a foaming agent is impregnated into the resin particles to obtain foamed particles, and the foamed particles are heated to obtain foamed particles. 6) A method in which a thermoplastic resin is supplied to an extruder and melted and kneaded, the molten thermoplastic resin is extruded in a strand shape from a die hole provided at the tip of the extruder, the extruded material is then guided into water to cool, and after cooling, it is cut into predetermined lengths to obtain columnar resin particles, a foaming agent is impregnated into the resin particles to obtain foamed particles, and the foamed particles are heated to obtain foamed particles.

[0088] The following describes in more detail a method in which a resin composition is extruded into the air to foam, then cut to form spherical particles which are then dropped into water for cooling.

[0089] This document describes an extruder used in the production of foamed particles according to the present invention. The foam particle manufacturing apparatus 10 shown in Figure 4 comprises an extruder (not shown) and a nozzle mold 1 provided at the tip of the extruder. A rotating shaft 2 is connected to the tip of the nozzle mold 1. The rotating shaft 2 passes through the front part 41a of a cooling drum 41, which constitutes a cooling member 4 described later, and is connected to a drive member 3 such as a motor. Multiple nozzle outlets 11 are formed at equal intervals on the same virtual circle A centered on the rotation axis 2 on the front end surface 1a of the nozzle mold 1 (see Figure 5).

[0090] The number of nozzles in the nozzle mold 1 (i.e., the number of outlets 11) is preferably 2 to 80. If there is only one nozzle, the manufacturing efficiency of foam particles may decrease. If there are more than 80 nozzles, the extruded foams extruded from adjacent nozzles may come into contact with each other and adhere together. Also, the foam particles obtained by cutting the extruded foam may adhere together. The number of nozzles is more preferably 5 to 60, and particularly preferably 8 to 50. The diameter (opening diameter) of the nozzle outlet 11 in the nozzle mold 1 is preferably 0.20 to 2.0 mm. If the opening diameter of the outlet 11 is less than 0.20 mm, the extrusion pressure may become too high, making extrusion foaming difficult. If the opening diameter of the outlet 11 is greater than 2.0 mm, the diameter of the foam particles may become larger, reducing the efficiency of filling the mold. The opening diameter of the outlet 11 is more preferably 0.30 to 1.6 mm, and particularly preferably 0.40 to 1.2 mm. The length of the land portion of the nozzle mold 1 is preferably 4 to 30 times the opening diameter of the outlet portion 11 in the nozzle of the nozzle mold 1. If the length is less than 4 times, fracture may occur and stable extrusion foaming may not be possible. If it is greater than 30 times, too much pressure may be applied to the nozzle mold 1 and extrusion foaming may not be possible. The length of the land portion is more preferably 5 to 20 times.

[0091] The rotating shaft 2 is positioned so as to protrude forward in the portion of the front end surface 1a of the nozzle mold 1 that is surrounded by the nozzle outlet portion 11. One or more rotating blades 5 are integrally provided on the outer circumferential surface of the rear end of the rotating shaft 2, and all rotating blades 5 are in constant contact with the front end surface 1a during rotation. When multiple rotating blades 5 are integrally provided on the rotating shaft 2, the multiple rotating blades 5 are arranged at equal intervals in the circumferential direction of the rotating shaft 2. Figure 5 shows, as an example, a case in which four rotating blades 5 are integrally provided on the outer circumferential surface of the rotating shaft 2. As the rotating shaft 2 rotates, the rotating blade 5 moves along a virtual circle A where the nozzle outlet 11 is formed, while constantly in contact with the front end surface 1a, and is configured to sequentially and continuously cut the extruded foam pushed out from the nozzle outlet 11. The foam particle manufacturing apparatus 10 is equipped with a cooling member 4 that surrounds at least the front end surface 1a of the nozzle mold 1 and the rotating shaft 2. The cooling member 4 comprises a bottomed cylindrical cooling drum 41 having a front circular front portion 41a with a larger diameter than the nozzle mold 1, and a cylindrical peripheral wall portion 41b extending rearward from the outer peripheral edge of the front portion 41a.

[0092] A supply port 41c for supplying coolant 42 is formed in the region of the peripheral wall portion 41b facing the outer surface of the nozzle mold 1. The supply port 41c penetrates the peripheral wall portion 41b. On the outer surface of the peripheral wall portion 41b, a supply pipe 41d for supplying coolant 42 into the cooling drum 41 is connected to the supply port 41c. The coolant 42 is configured to be supplied diagonally forward along the inner surface of the peripheral wall portion 41b of the cooling drum 41 through the supply pipe 41d.

[0093] An outlet 41e is formed on the lower front end surface of the peripheral wall portion 41b. The outlet 41e penetrates the peripheral wall portion 41b. An outlet pipe 41f is connected to the outlet 41e on the outer surface of the peripheral wall portion 41b. The extruder is not particularly limited to conventionally used extruders, and examples include single-screw extruders, twin-screw extruders, and tandem extruders which are multiple extruders linked together.

[0094] A method for producing foamed particles using the foamed particle production apparatus 10 will be described. Coolant 42 is supplied into the cooling drum 41 from the supply pipe 41d via the supply port 41c. The supplied coolant 42 moves forward (towards the front 41a) in a spiral pattern along the inner surface of the peripheral wall 41b due to the centrifugal force associated with the flow velocity during supply. As the coolant 42 moves along the inner surface of the peripheral wall 41b, it gradually spreads in a direction perpendicular to the direction of travel (i.e., in the circumferential direction of the peripheral wall 41b). The coolant 42 that has spread in the circumferential direction of the peripheral wall 41b completely covers the inner surface of the peripheral wall 41b in front of the supply port 41c.

[0095] The coolant 42 is not particularly limited as long as it can cool the foam particles, and examples include water, alcohol, etc., but water is preferred when considering disposal after use. The temperature of the coolant 42 is preferably 10 to 40°C. If the coolant temperature is 10°C or higher, the nozzle mold 1 located near the cooling drum 41 will not be excessively cooled, and the resin composition can be more smoothly extruded from the outlet 11. If the coolant temperature is 40°C or lower, the particulate cut material can be cooled more quickly.

[0096] The glass transition temperature (Tg) of the polyester resin (raw material polyester resin) blended into the resin composition is preferably 50 to 100°C, more preferably 60 to 90°C, and even more preferably 70 to 85°C. If Tg is above the lower limit, the heat resistance and heating dimensional stability can be further improved. If Tg is below the upper limit, the molding cycle can be shortened to increase productivity and improve moldability. "Moldability" refers to the ability to approach a desired shape when, for example, foamed particles are filled into the cavity of a mold and heated to cause secondary foaming. The closer to the desired shape, the "better" the moldability.

[0097] The melting point of the raw polyester resin is preferably 230-270°C, more preferably 240-260°C, and even more preferably 245-255°C. If the melting point is above the lower limit, the heat resistance and dimensional stability when heated can be further improved. If the melting point is below the upper limit, the molding cycle can be shortened, increasing productivity and improving moldability.

[0098] The intrinsic viscosity (IV value) of the raw polyester resin is preferably 0.50 to 1.5, more preferably 0.60 to 1.3, and even more preferably 0.70 to 1.2. If the IV value is above the lower limit, bubble breakage during foaming is suppressed, and the open-cell ratio can be further reduced. If the IV value is below the upper limit, the density can be further reduced, the surface of the foamed particle molded body can be made smoother, and the appearance can be improved. The IV value can be measured according to the method specified in JIS K7367-5(2000).

[0099] The number-average molecular weight (Mn) of the raw polyester resin is 0.050 × 10⁻⁶. 5 ~0.40 × 10 5 Preferably, 0.10 × 10 5 ~0.35 × 10 5 More preferably, 0.15 × 10 5 ~0.30 × 10 5 That is even more preferable. If the number-average molecular weight (Mn) of the raw polyester resin is above the lower limit, impact resistance can be improved. If the number-average molecular weight (Mn) of the raw polyester resin is below the upper limit, heat resistance can be further improved.

[0100] The mass-average molecular weight Mw of the raw polyester resin is 0.30 × 10⁻⁶. 5 ~1.3 × 10 5 Preferably, 0.40 × 10 5 ~1.2 × 10 5 More preferably, 0.50 × 10 5 ~1.2 × 10 5 That is even more preferable. If the mass-average molecular weight Mw of the raw polyester resin is within the above range, the impact resistance can be further enhanced.

[0101] The average molecular weight Mz of the raw polyester resin is 0.20 × 10⁻⁶. 5 ~2.5×10 5 Preferably, 0.30 × 10 5 ~2.0×10 5 More preferably, 0.90 × 10 5 ~1.8×10 5 That is even more preferable. If the average molecular weight Mz of the raw polyester resin is above the lower limit, the heat resistance can be improved. If the average molecular weight Mz of the raw polyester resin is below the upper limit, the moldability can be improved.

[0102] The molecular weight distribution of the raw material polyester resin, expressed as Mw / Mn, is preferably 1.5 to 5.0, more preferably 2.0 to 4.0, and even more preferably 2.5 to 3.5. If the Mw / Mn ratio of the raw polyester resin is within the above range, the moldability can be further improved. The number-average molecular weight Mn, mass-average molecular weight Mw, and Z-average molecular weight Mz of the raw polyester resin can be measured using the same method as for the number-average molecular weight Mn, mass-average molecular weight Mw, and Z-average molecular weight Mz of the foamed particles.

[0103] The glass transition temperature (Tg) of the polyimide resin (raw material polyimide resin) blended into the resin composition is preferably 190 to 240°C, more preferably 200 to 230°C, and even more preferably 210 to 220°C. If the glass transition temperature (Tg) of the raw material polyimide resin is above the lower limit, the heat resistance and heat resistance can be further improved. If the glass transition temperature (Tg) of the raw material polyimide resin is below the upper limit, the molding cycle can be shortened, productivity can be increased, and moldability can be improved.

[0104] The melt flow rate (MFR) of the raw polyimide resin is preferably 3.0 to 30 g / 10 min, more preferably 5.0 to 25 g / 10 min, and even more preferably 7.0 to 20 g / 10 min. If the MFR of the raw polyimide resin is above the lower limit, the molding cycle can be shortened, increasing productivity and improving moldability. If the MFR is below the upper limit, the heat resistance and heat resistance can be further improved.

[0105] The number-average molecular weight (Mn) of the raw material polyimide resin is 0.10 × 10⁻⁶. 5 ~0.50 × 10 5 Preferably, 0.15 × 10 5 ~0.30 × 10 5 More preferably, 0.20 × 10 5 ~0.25 × 10 5 This is even more preferable. Impact resistance can be further improved if the number-average molecular weight Mn of the raw polyimide resin is above the above lower limit. Moldability can be further improved if the average molecular weight Mn of the raw polyimide resin is below the above upper limit.

[0106] The mass-average molecular weight Mw of the raw material polyimide resin is 0.20 × 10⁻⁶. 5 ~0.80 × 10 5 Preferably, 0.30 × 10 5 ~0.70 × 10 5 More preferably, 0.40 × 10 5 ~0.60 × 10 5 This is even more preferable. Impact resistance can be further improved if the mass average molecular weight Mw of the raw material polyimide resin is above the lower limit. Moldability can be further improved if the mass average molecular weight Mw of the raw material polyimide resin is below the upper limit.

[0107] The average molecular weight Mz of the raw material polyimide resin is 0.40 × 10⁻⁶. 5 ~1.2 × 10 5 Preferably, 0.50 × 10 5 ~1.0×10 5 More preferably, 0.60 × 10 5 ~0.90 × 10 5 That is even more preferable. If the average molecular weight Mz of the raw polyimide resin is above the lower limit, the heat resistance can be improved. If the average molecular weight Mz of the raw polyimide resin is below the upper limit, the moldability can be improved.

[0108] The molecular weight distribution of the raw material polyimide resin, expressed as Mw / Mn, is preferably 1.0 to 3.0, more preferably 1.5 to 2.5, and even more preferably 2.0 to 2.5. If the Mw / Mn ratio of the raw polyimide resin is within the above range, the moldability can be further improved. The number-average molecular weight Mn, mass-average molecular weight Mw, and Z-average molecular weight Mz of the raw polyimide resin can be measured in the same way as the number-average molecular weight Mn, mass-average molecular weight Mw, and Z-average molecular weight Mz of the foamed particles.

[0109] These resin compositions are extruded from the nozzle outlet 11 while the rotating blades 5 are rotated. The resin compositions become extruded foam from the nozzle mold 1 and are cut by the rotating blades 5 to form particulate cut material. All rotating blades 5 are constantly in contact with the front end surface 1a while rotating, and the extruded foam from the nozzle mold 1 is cut in the air at regular time intervals by the shear stress generated between the rotating blades 5 and the edge of the nozzle outlet 11 to form particulate cut material. At this time, water may be sprayed onto the extruded foam in a mist form, as long as the cooling of the extruded foam does not become excessive.

[0110] Within the nozzle of the nozzle mold 1, the resin composition is prevented from foaming. Immediately after being discharged from the nozzle outlet 11, the resin composition is not yet foamed, and begins to foam a short time after discharge. Therefore, the extruded foam consists of an unfoamed portion immediately after being discharged from the nozzle outlet 11, and a foamed portion that is continuous with this unfoamed portion and was extruded prior to the unfoamed portion, and is in the process of foaming. The unfoamed portion remains in that state from the time it is discharged from the nozzle outlet 11 until foaming begins. The time that this unfoamed portion is maintained can be adjusted by the resin pressure at the nozzle outlet 11, the amount of foaming agent, etc. If the resin pressure at the nozzle outlet 11 is high, the resin composition will not foam immediately after being extruded from the nozzle mold 1, and will remain in an unfoamed state. The discharge pressure of the thermoplastic resin at the nozzle outlet 11 can be adjusted by the opening diameter of the nozzle outlet 11, the extrusion amount, the melt viscosity of the resin composition, and the melt tension. In addition, by adjusting the amount of foaming agent to an appropriate amount, foaming of the thermoplastic resin composition inside the nozzle mold 1 can be prevented, and the unfoamed portion can be reliably formed. Since all the rotating blades 5 are constantly in contact with the front end surface 1a while cutting the extruded foam, the extruded foam becomes particulate material cut in the unfoamed portion immediately after being discharged from the nozzle outlet 11.

[0111] The rotational speed of the rotating blade 5 is preferably 2000 to 10000 rpm, more preferably 2000 to 9000 rpm, and particularly preferably 2000 to 8000 rpm. If the rotational speed is above the lower limit, the extruded foam can be cut more reliably by the rotating blade 5, preventing adhesion and making the foam particles a more uniform shape. If the rotational speed is below the upper limit, sufficient time is secured for the foam to reach the coolant 42 described later, allowing the bulk expansion ratio to be further increased.

[0112] As shown in Figure 6, the particulate material P cut by the rotating blade 5 is scattered toward the inner wall of the cooling drum 41 at the same time as the cutting stress from the rotating blade 5, and collides with the coolant 42 covering the inner surface of the peripheral wall portion 41b. The particulate material continues to foam until it collides with the coolant 42, and grows into a roughly spherical shape through foaming. Therefore, the resulting foamed particles are roughly spherical. In this case, it is preferable that the particulate material P collides with the coolant 42 obliquely to the surface of the coolant 42 and from upstream to downstream in the flow direction X of the coolant 42 (see Figure 6). When the particulate material collides with the coolant 42, by having the particulate material P collide with the coolant 42 from a direction following the flow of the coolant 42, the particulate material P is not bounced off the surface of the coolant 42, and enters the coolant 42 smoothly and reliably, where it is cooled by the coolant 42 and becomes foamed particles.

[0113] According to this embodiment, since the particulate cut material is immediately cooled with the cooling liquid 42 after the extruded foam is cut by the rotating blade 5, excessive foaming of the particulate cut material is prevented, and foamed particles with a desired bulk expansion ratio can be obtained. In addition, since the particulate cut material is cooled immediately after cutting the extruded foam, the increase in the crystallinity of the foam particles is suppressed. As a result, the foam particles exhibit excellent secondary foaming and heat-sealing properties, and the resulting foam particle molded body has excellent mechanical strength. Furthermore, by increasing the crystallinity of the foam particle molded body during in-mold foaming, the dimensional stability during heating can be further enhanced.

[0114] The foam particles cooled by the coolant 42 flow into the discharge pipe 41f via the discharge port 41e and are discharged outside the cooling drum 41. The discharged foam particles are separated from the coolant 42 and dried as necessary. Methods for separating the foam particles from the coolant 42 include conventionally known solid-liquid separation methods, such as passing them through a sieve.

[0115] (Thermoplastic resin foam particle molded product) The thermoplastic resin foam particle molded article (foam particle molded article) of this embodiment is made by foaming foam particles and fusing them together. Examples of foam particle molded articles include parts for transportation equipment such as automobiles, railway vehicles, aircraft, or ships, cushioning materials and housings for electrical products, transport containers, packaging materials, structural members, and heat insulating materials. Examples of automobile parts include battery cases, battery trays, members used near the engine, exterior materials, and heat insulating materials. Examples of railway vehicle members include sheet core materials, exterior materials, and heat insulating materials.

[0116] The size of the foam particle molded body is not particularly limited and is determined appropriately considering the application.

[0117] The ratio of polyester resin to thermoplastic resin in the foamed particle molded article is the same as the ratio of polyester resin to thermoplastic resin in the foamed particles. The ratio of polyimide resin to thermoplastic resin in the foamed particle molded article is the same as the ratio of polyimide resin to thermoplastic resin in the foamed particles.

[0118] The polyimide resin content in a foamed particle molded body can be measured by slicing the foamed particle molded body into a sample of any thickness (e.g., 0.2 mm) along a direction perpendicular to the thickness direction (planar direction) from the surface of the foamed particle molded body, and using this as the measurement sample, in the same manner as the polyimide resin content in the foamed particles.

[0119] The foamed particle molded body exhibits a single glass transition temperature (Tg). This single Tg is achieved through the compatibility of the polyester resin and the polyimide resin. Because the foamed particle molded body has a single glass transition temperature (Tg), it is higher than the glass transition temperature (Tg) of the polyester resin, resulting in increased heat resistance of the foamed particle molded body. The glass transition temperature (Tg) of the foamed particle molded body is preferably 80 to 130°C, more preferably 80 to 125°C, even more preferably 80 to 120°C, and particularly preferably 80 to 100°C. If Tg is above the lower limit, the heat resistance and heating dimensional stability of the foamed particle molded body can be further improved. If Tg is below the upper limit, moldability is improved and the appearance is beautifully finished.

[0120] The endothermic-exothermic difference of the foamed particle molded body is preferably 3.0 to 35 J / g, more preferably 10 to 30 J / g, and even more preferably 15 to 28 J / g. If the endothermic-exothermic difference is above the lower limit, the degree of crystallinity increases, and the heating dimensional stability of the foamed particle molded body can be improved. If the endothermic-exothermic difference is below the upper limit, the degree of crystallinity does not increase too much, and the impact resistance of the foamed particle molded body can be improved. The endothermic-exothermic difference is determined by differential scanning calorimetry of the heat flux at a heating rate of 10°C / min and is the difference between the amount of heat absorbed and the amount of heat released.

[0121] The average molecular weight Mz of the foamed particle molded body is 2.5 × 10⁻⁶. 5 ~5.0×10 5 And, 2.9 × 10 5 ~5.0×10 5 Preferably, 3.2 × 10 5 ~5.0×10 5 This is preferable. If the Z average molecular weight Mz of the foamed particle molded body is at least the above lower limit value, the closed cell ratio can be further reduced and the moldability can be enhanced. If the Z average molecular weight Mz of the foamed particle molded body is at most the above upper limit value, the expansion ratio can be further increased and the foamed particles can be thermally fused well to each other, enhancing the moldability.

[0122] The number average molecular weight Mn of the foamed particle molded body is preferably 0.10×10 5 ~0.30×10 5 more preferably 0.15×10 5 ~0.25×10 5 even more preferably 0.18×10 5 ~0.23×10 5 . When the number average molecular weight Mn of the foamed particle molded body is at least the above lower limit value, the impact resistance can be enhanced. When the number average molecular weight Mn of the foamed particle molded body is at most the above upper limit value, the moldability can be further enhanced.

[0123] The mass average molecular weight Mw of the foamed particle molded body is preferably 0.50×10 5 ~2.0×10 5 [[ID=2H]]more preferably 0.70×10 5 ~1.5×10 5 even more preferably 0.80×10 5 ~1.2×10 5 . When the mass average molecular weight Mw of the foamed particle molded body is at least the above lower limit value, the impact resistance can be enhanced. When the mass average molecular weight Mw of the foamed particle molded body is at most the above upper limit value, the moldability can be further enhanced.

[0124] The number average molecular weight Mn, mass average molecular weight Mw, and Z average molecular weight Mz of the foamed particle molded body can be measured in the same manner as the number average molecular weight Mn, mass average molecular weight Mw, and Z average molecular weight Mz of the foamed particles. The number average molecular weight Mn, mass average molecular weight Mw, and Z average molecular weight Mz of the foamed particle molded body are adjusted by combinations of the types and amounts of the raw material polyester resin and raw material polyimide resin, and the types and amounts of the crosslinking agent, etc. Note that the number average molecular weight Mn, mass average molecular weight Mw, and Z average molecular weight Mz of the foamed particle molded body can be regarded as the same as the number average molecular weight Mn, mass average molecular weight Mw, and Z average molecular weight Mz of the thermoplastic resin constituting the foamed particle molded body.

[0125] In the foamed particle molded body, the temperature at which the loss tangent tanδ is maximum in the solid viscoelasticity measurement at a heating rate of 5 °C / min and a frequency of 1 Hz is preferably 120 to 230 °C, more preferably 130 to 225 °C, and even more preferably 150 to 220 °C. If the temperature at which the loss tangent tanδ is maximum is at least the above lower limit value, the temperature at which the foamed particle molded body softens becomes higher, and the heat resistance strength of the foamed particle molded body can be further increased. If the temperature at which the loss tangent tanδ is maximum is at most the above upper limit value, the temperature at which the foamed particle molded body softens does not become excessively high, and the moldability can be further increased.

[0126] The open cell ratio of the foamed particle molded body is, for example, preferably 20% or less, more preferably 18% or less, and even more preferably 16% or less. When the open cell ratio of the foamed particle molded body is at most the above upper limit value, the impact resistance of the foamed particle molded body can be further increased. The open cell ratio of the foamed particle molded body is determined by the method described in JIS K7138:2006 "Rigid Cellular Plastics - Determination of Open Cell Ratio and Closed Cell Ratio".

[0127] The apparent density of the foamed particle molded body is, for example, preferably 0.027 to 0.675 g / cm 3 more preferably 0.045 to 0.45 g / cm 3 even more preferably 0.0675 to 0.27 g / cm 3 When the apparent density of the foamed particle molded body is at least the above lower limit value, the impact resistance of the foamed particle molded body can be further increased. When the apparent density of the foamed particle molded body is at most the above upper limit value, the foamed particle molded body can be made lighter.

[0128] The foaming ratio of the foamed particle molded body is preferably 2 to 50 times, more preferably 3 to 30 times, and even more preferably 5 to 20 times. If the foaming ratio of the foamed particle molded body is above the lower limit, the impact resistance of the foamed particle molded body can be further increased. If the foaming ratio of the foamed particle molded body is below the upper limit, the mechanical strength of the foamed particle molded body can be further increased.

[0129] The average bubble diameter of the foamed particle molded body is preferably, for example, 5.0 to 500 μm, more preferably 10 to 400 μm, and even more preferably 20 to 300 μm. If the average bubble diameter of the foamed particle molded body is above the lower limit, the impact resistance of the foamed particle molded body can be further improved. If the average bubble diameter of the foamed particle molded body is below the upper limit, the surface smoothness of the foamed particle molded body can be further improved. The average bubble diameter of the foamed particle molded body can be measured in accordance with the method described in ASTM D2842-69.

[0130] In foamed particle molded articles, the flame retardancy (flame retardancy grade according to the UL94 standard), measured in accordance with the UL94 vertical method (11 mm vertical combustion test), is preferably V-2 or higher, more preferably V-1 or higher, and even more preferably V-0. The flame retardancy grade of the foamed particle molded product can be adjusted by controlling the content of polyimide resin, phosphorus-based flame retardant, and other factors. For example, by setting the polyimide resin content to 25% by mass or more relative to the total mass of the thermoplastic resin, flame retardancy can be further enhanced, making it more reliable to achieve V-1 or higher. In addition, the flame retardancy grades of the UL94 standard increase in the order of V-2, V-1, and V-0. Furthermore, examples of the UL-94 vertical method (11mm vertical combustion test) include the method described by Aki Hosogai et al., "Material Flammability Test for Fire Safety Evaluation," Journal of the Combustion Society of Japan, Vol. 56, No. 175, 2014, pp. 47-58.

[0131] <Manufacturing method> A foamed particle molded article using foamed particles can be manufactured by conventionally known manufacturing methods. Examples of methods for manufacturing foamed particle molded articles include the following methods. 1) A method in which foamed particles (bulk expansion ratio: 2 to 50 times) are filled into a mold, heated, and the foamed particles are subjected to secondary foaming to form secondary foamed particles and fused together, thereby forming a foamed particle molded body (foam expansion ratio: 2 to 50 times) by in-mold foam molding (heat molding process). 2) A method comprising heating foamed particles to create pre-foamed particles (foaming ratio: 2 to 50 times) with a desired bulk foaming ratio (pre-foaming step), filling a mold with the pre-foamed particles, heating the mold to cause secondary foaming of the pre-foamed particles to create secondary foamed particles while fusing them together, and forming a foamed particle molded body (foaming ratio: 2 to 50 times) by in-mold foam molding (heat molding step).

[0132] One method for inducing secondary foaming is to heat the inside of the mold cavity with steam. The temperature for secondary foaming is preferably, for example, 100 to 180°C. The secondary foaming time (i.e., the time for supplying steam to the mold) is preferably 5 to 120 seconds. In the secondary foaming process, water vapor may be supplied into the cavity from the female mold side, or from the male mold side, or these may be done alternately. Furthermore, the foam particles may be impregnated with an inert gas or air (hereinafter referred to as "inert gas, etc.") to improve their secondary foaming ability (internal pressure application step). Examples of inert gases include carbon dioxide, nitrogen, helium, and argon. One method for impregnating foamed particles with an inert gas is to place the foamed particles in an atmosphere containing an inert gas at a pressure equal to or greater than atmospheric pressure. The foamed particles may be impregnated with an inert gas before being filled into the mold, or they may be impregnated after being filled into the mold by placing the mold and the foamed particles together in an atmosphere containing an inert gas. If the inert gas is nitrogen, the foamed particles may be left in a nitrogen atmosphere with a gauge pressure (relative to atmospheric pressure) of 0.1 to 2 MPa for 20 minutes to 24 hours.

[0133] Following the heat molding process, the degree of crystallinity of the thermoplastic resin may be increased by further heating the foamed particle molded body in the mold (heat retention process).

[0134] <Applications of thermoplastic foam particle molded products> The thermoplastic resin foam particle molded articles of the present invention are suitable for applications such as motorcycles, electric bicycles, automobile electrical components, and heat-resistant automobile parts. In particular, they are suitable for use as internal components of hard disks, motorcycles, electric bicycles, and automobile electrical components where precision molding is required.

[0135] Examples of electrical components in motorcycles, electric bicycles, and automobiles include battery cases and battery housings.

[0136] Suitable heat-resistant automotive parts include, for example, alternator terminals, alternator connectors, IC regulators, potentiometer bases for light dew, various valves such as exhaust gas valves, engine coolant joints, carburetor main bodies, carburetor spacers, exhaust gas sensors, coolant sensors, oil temperature sensors, brake pad wear sensors, throttle position sensors, crankshaft position sensors, air flow meters, brake pad wear sensors, air conditioner thermostat bases, heater hot air flow control valves, radiator motor brush holders, water pump impellers, turbine vanes, wiper motor related parts, distributors, starter switches, starter relays, transmission wire harnesses, window washer nozzles, air conditioner panel switch circuit boards, fuel-related solenoid valve coils, fuse connectors, horn terminals, electrical component insulating plates, stepper motor rotors, brake pistons, solenoid bobbins, ignition system cases, wheel caps, lamp sockets, lamp housings, lamp extensions, and lamp reflectors.

[0137] (Foam resin composite) The foamed resin composite comprises a foamed particle molded body of the present invention and a fiber-reinforced resin layer (surface material) provided on at least a portion of the surface of the foamed particle molded body. Foamed resin composites have excellent heat resistance and mechanical strength, and can be used in a wide range of applications as components for transportation equipment. In addition, foamed resin composites can be suitably used as building materials, wind turbine blades, robot arms, housings for electrical products, cushioning material for helmets, transport containers such as agricultural product boxes and insulated containers, rotor blades for industrial helicopters, and parts packaging materials. Examples of components for transportation equipment include structural members that constitute the main body of transportation equipment such as automobiles, railway vehicles, aircraft, or ships. Examples of structural members that constitute the main body of an automobile include door panels, door inners, bumpers, fenders, fender supports, engine covers, roof panels, trunk lids, floor panels, center tunnels, crash boxes, and cowls. For example, using a resin composite for a door panel that was conventionally made of steel plate allows for a significant reduction in weight while maintaining approximately the same rigidity as a steel plate door panel, thus contributing to the weight reduction of the automobile. Examples of structural members that constitute the main body of a railway vehicle include back shells, tables, leg rests, wall panels, and floor panels.

[0138] For example, the foamed resin composite 100 in Figure 7 has a flat foamed particle molded body (foamed layer) 102 and fiber-reinforced resin layers 104 provided on both sides of the foamed particle molded body 102.

[0139] The foamed layer 102 is the foamed particle molded body of the present invention as described above. The fibers constituting the fiber-reinforced resin layer 104 are not particularly limited, and examples include carbon fibers, glass fibers, aramid fibers, boron fibers, and metal fibers. Among these, carbon fibers, glass fibers, and aramid fibers are preferred, and carbon fibers are more preferred, due to their excellent mechanical strength and heat resistance. The form of the fibers is not particularly limited and includes, for example, woven fabrics, knitted fabrics, nonwoven fabrics, and face materials made by binding (sewing) fiber bundles (strands) of fibers aligned in one direction with synthetic resin threads such as polyamide resin or polyester resin, or stitching threads such as glass fiber thread. Examples of weaving methods for woven fabrics include plain weave, twill weave, satin weave, etc. The fibers may be (1) a multilayer surface material formed by laminating multiple woven fabrics, knitted fabrics, or nonwoven fabrics together or in any combination thereof, or (2) a multilayer surface material formed by overlapping multiple surface materials, each made by binding (sewing) fiber bundles (strands) with fibers aligned in one direction together with synthetic resin threads such as polyamide resin or polyester resin, or stitching threads such as glass fiber threads, so that the fiber directions of the fiber bundles are oriented in different directions from each other, and then integrating (sewing) the overlapped surface materials together with synthetic resin threads such as polyamide resin or polyester resin, or stitching threads such as glass fiber threads.

[0140] Examples of resins included in the fiber-reinforced resin layer 104 include uncured thermosetting resins and thermoplastic resins. The thermosetting resin is not particularly limited and includes, for example, epoxy resins, unsaturated polyester resins, phenolic resins, melamine resins, polyurethane resins, silicone resins, maleimide resins, vinyl ester resins, cyanate ester resins, and resins obtained by prepolymerizing maleimide resin and cyanate ester resin. Epoxy resins and vinyl ester resins are preferred due to their excellent heat resistance, elastic modulus, and chemical resistance. The thermosetting resin may contain additives such as curing agents and curing accelerators. The thermosetting resin may be used alone or in combination of two or more types. The thermoplastic resin is not particularly limited and includes, for example, polyethylene resins, polyolefin resins such as polypropylene resins, acrylic resins, polyester resins, polyamide resins, and polycarbonate resins. The resin content of the fiber-reinforced resin layer 104 is preferably 20 to 70% by mass, and more preferably 30 to 60% by mass, relative to the total mass of the fiber-reinforced resin layer 104. If the resin content is above the lower limit, the bonding between fibers is further enhanced, and the mechanical strength of the resulting foamed resin composite is further increased. If the resin content is below the upper limit, the amount of resin present between fibers does not become too large, and the mechanical strength of the fiber-reinforced resin layer 104 is further enhanced, and the mechanical strength of the resulting foamed resin composite is further enhanced.

[0141] The method for impregnating the fibers with resin is not particularly limited and includes, for example, (1) immersing the fibers in resin, and (2) coating the fibers with resin.

[0142] In this embodiment, the materials of the fiber-reinforced resin layers located on both sides of the foamed particle molded body may be the same or different.

[0143] The thickness of the fiber-reinforced resin layer 104 is preferably 0.10 to 5.0 mm, and more preferably 0.30 to 3.0 mm. If the thickness of the fiber-reinforced resin layer 104 is greater than or equal to the lower limit, the mechanical strength of the foamed resin composite 100 can be further increased. If the thickness of the fiber-reinforced resin layer 104 is less than or equal to the upper limit, the weight of the foamed resin composite 100 can be further reduced. In this embodiment, the thicknesses of the fiber-reinforced resin layers 104 located on both sides of the foamed particle molded body 102 may be the same or different.

[0144] <Manufacturing method> The method for providing the fiber-reinforced resin layer 104 on the surface of the foamed particle molded body 102 is not particularly limited, and for example, (1) a method of laminating and joining the fiber-reinforced resin layer 104 to the surface of the foamed particle molded body 102 via an adhesive, (2) a method of laminating the fiber-reinforced resin layer 104 impregnated with thermoplastic resin to the surface of the foamed particle molded body 102 and joining the fiber-reinforced resin layer 104 to the surface of the foamed particle molded body 102 using the thermoplastic resin as a binder, (3) foamed particle molded body 102 Methods include (4) laminating a fiber-reinforced resin layer 104 impregnated with an uncured thermosetting resin onto the surface of the foam particle molded body 102, and joining the fiber-reinforced resin layer 104 to the foam particle molded body 102 using the cured thermosetting resin as a binder, and laminating a heated and softened fiber-reinforced resin layer 104 onto the surface of the foam particle molded body 102, and joining the fiber-reinforced resin layer 104 to the foam particle molded body 102 by pressing the fiber-reinforced resin layer 104 onto the surface of the foam particle molded body 102. In method (4), it is also possible to deform the fiber-reinforced resin layer 104 along the surface of the foam particle molded body 102. Here, since the foam particle molded body 102 of the present invention has excellent load-bearing capacity in high-temperature environments, method (4) can also be suitably used. By these methods, a fiber-reinforced resin layer 104 can be integrally provided on the surface of the foamed particle molded body 102. Methods for bonding a fiber-reinforced resin layer 104 to the surface of a foamed particle molded body 102 include, for example, the autoclave method, the hand lay-up method, the spray-up method, the PCM (Prepreg Compression Molding) method, the RTM (Resin Transfer Molding) method, and the VaRTM (Vacuum assisted Resin Transfer Molding) method.

[0145] The foamed resin composite of the above-described embodiment has a flat foamed particle molded body, but the present invention is not limited thereto, and the shape of the foamed particle molded body can be appropriately determined according to the application. That is, the shape of the foamed resin composite can be appropriately determined according to the application. In the above-described embodiment, fiber-reinforced resin layers are provided on both sides of the foamed particle molded body. However, the present invention is not limited thereto. The fiber-reinforced resin layer may be provided on only one side of the foamed particle molded body, or on only a part of the surface of the foamed particle molded body.

[0146] The foamed particle molded body of this embodiment contains a polyester resin, which enhances its dimensional stability during heating and improves its heat resistance. Because the foamed particles of this embodiment contain a polyimide resin, the glass transition temperature (Tg) can be increased, thereby improving the heat resistance. For this reason, the foamed particle molded article obtained by heat molding the foamed particles has excellent heat resistance. In addition, the foamed particle molded article of this embodiment has a polyimide resin content within a specific range, thus providing excellent moldability while increasing heat resistance. Furthermore, the foamed particle molded article of this embodiment contains a specific amount of phosphorus-based flame retardant, and therefore exhibits excellent flame retardancy and moldability.

[0147] In one preferred embodiment of the thermoplastic resin foam particles or thermoplastic resin foam particle molded article of the present invention, The content of the polyimide resin is 30 to 40% by mass relative to the total mass of the thermoplastic resin. The phosphorus content is 0.30 to 0.66% by mass relative to the total mass of the thermoplastic resin. The degree of crystallinity of the aforementioned thermoplastic resin foam particles is 3.3 to 6.3%. Furthermore, in this embodiment, it is even more preferable that the open-cell ratio of the thermoplastic resin foam particles is 3.4 to 16%. According to the above embodiment, particularly excellent moldability, heating dimensional change rate, combustion test, and flame retardancy can be achieved. [Examples]

[0148] The present invention will be described below with reference to examples, but the present invention is not limited thereto.

[0149] (Raw materials used) <Polyester resin> • PET(A): Manufactured by Lotte Chemical Co., Ltd., product name "BCB80", glass transition temperature Tg: 78.7℃, melting point: 247.2℃, IV value: 0.80, biomass content: 30%. • PET(B): Manufactured by Mitsui Chemicals, product name "SA-135", glass transition temperature Tg: 75.0℃, melting point: 247.0℃, IV value: 0.82, biomass content: 0%.

[0150] <Polyimide resin> PEI(A): Polyetherimide, manufactured by SABIC Innovative Plastics, trade name "Ultem1000", glass transition temperature Tg: 217℃, MFR: 9g / 10min.

[0151] <Phosphorus-based flame retardant> • Flame retardant (a): Flame retardant-containing PET masterbatch, manufactured by Toyo Color Co., Ltd., product name "NF POLY 1450 MB", phosphorus content: 4.4% by mass. • Flame retardant (b): Flame retardant-containing PET masterbatch, manufactured by Toyo Color Co., Ltd., product name "NF POLY 1477 MB", phosphorus content: 3.0% by mass. • Flame retardant (c): Flame retardant, manufactured by Teijin Corporation, product name "Fire Guard FCX-210", phosphorus content: 15% by mass.

[0152] <Talc Masterbatch> • The nucleating agent MB is a masterbatch consisting of PET = 58% by mass and talc = 42% by mass.

[0153] <Crosslinking agent> • PMDA: Pyromellitic anhydride.

[0154] <Foaming agent> Butane: A mixture of isobutane and n-butane. Isobutane:n-butane = 35:65 (by mass).

[0155] (Evaluation method) <density> ≪Bulk density of foamed particles≫ The bulk density of the expanded particles was measured in accordance with JIS K6911:1995 "General Test Methods for Thermosetting Plastics". The measurement was carried out using an apparent density measuring instrument conforming to JIS K6911, and the bulk density of the expanded particles was determined based on the following formula (s1). Bulk density of expanded particles (g / cm 3 ) = [Mass of graduated cylinder with expanded particles (g) - Mass of graduated cylinder (g)] / [Volume of graduated cylinder (cm 3 )] ··· (s1)

[0156] ≪Density of expanded particle molded body≫ The density of the expanded particle molded body was measured by the method described in JIS K7222:1999 "Foamed Plastics and Rubber - Measurement of Apparent Density". An expanded particle molded body of 100 cm 3 or more was cut so as not to change the original cell structure of the material, and its mass was measured. The density was calculated by the following formula (s2). Density (g / cm 3 ) = Mass of expanded particle molded body (g) / Volume of expanded particle molded body (cm 3 ) ··· (s2)

[0157] <Expansion ratio> ≪Expanded particles≫ The bulk expansion ratio of the expanded particles was determined as the value obtained by calculating the density of the thermoplastic resin from the blending ratio of each example and dividing it by the bulk density of the obtained expanded particles. The following values were used for the density of each resin. · PET: 1.35 g / cm 3 . · PEI: 1.28 g / cm 3 . · Flame retardant MB: 1.35 g / cm 3 .

[0158] ≪Expanded particle molded body≫ The expansion ratio of the expanded particle molded body was determined as the value obtained by calculating the density of the thermoplastic resin from the blending ratio of each example and dividing it by the density of the obtained expanded particle molded body. The following values were used for the density of each resin. · PET: 1.35 g / cm 3 . PEI: 1.28 g / cm³ 3 . Flame retardant MB: 1.35 g / cm³ 3 .

[0159] <Open cell ratio> The open-cell ratio of the foamed particles was measured using the following method. First, a sample cup for a volumetric air-comparative hydrometer was prepared, and the total mass A (g) of foamed particles filling approximately 80% of this sample cup was measured. Next, the total volume B (cm³) of the foamed particles was measured. 3 The specific gravity was measured using a hydrometer with the 1-1 / 2-1 atmosphere method. The "Volume-Measurement Air Comparison Hydrometer Model 1000" from Tokyo Science Co., Ltd. was used for the measurement. A wire mesh container was prepared and immersed in water. The mass C (g) of the wire mesh container in this immersed state was measured. All the foam particles were placed inside the wire mesh container, and this container was immersed in water again. The combined mass D (g) of the wire mesh container and the total amount of foam particles inside the container in this immersed state was measured. A Yamato Scale Co., Ltd. "Electronic Balance HB3000" (minimum scale 0.01g) was used to measure the mass of the foam particles and the wire mesh container. Then, based on the following formula, the apparent volume E (cm³) of the foamed particles is calculated. 3 ) is calculated, and this apparent volume E and the total volume B (cm³) of the foam particles are used to calculate the volume. 3 Based on this, the open-cell ratio of the foamed particles was calculated using the following formula (s3). Note that the volume of 1g of water was 1cm³. 3 Furthermore, in this measurement, the foamed particles were first stored for 16 hours under conditions of JIS K7100-1999 Symbol 23 / 50, Class 2, and then measured under the same conditions. Open cell percentage (%) = 100 × (EB) / E···(s3) (E=A+(CD))

[0160] <Glass transition temperature Tg> The glass transition temperature (Tg) was measured using the methods described in JIS K7121:1987 and JIS K7121:2012. However, the sampling method and temperature conditions were as follows. Samples cut from foamed particles or molded foamed particles were packed tightly into the bottom of an aluminum measuring container at a concentration of 5.5 ± 0.5 mg, and then the aluminum lid was placed over them. Differential scanning calorimetry was then performed using a Hitachi High-Tech Science Corporation "DSC7000X, AS-3" differential scanning calorimetry meter. Under a nitrogen gas flow rate of 20 mL / min, the samples were heated and cooled in the following steps 1 to 4 to obtain DSC curves. (Step 1) Hold at 30°C for 2 minutes. (Step 2) Increase the temperature from 30°C to 300°C at a rate of 10°C / min (first heating process), and hold for 10 minutes. (Step 3) Quickly remove the sample and allow it to cool in an environment of 25±10℃. (Step 4) The temperature was increased from 30°C to 300°C at a rate of 10°C / min (second heating process). Alumina was used as the reference material. Using the analysis software attached to the instrument, the temperatures at the top of the melting peak and crystallization peak observed during the second heating process were read and determined as the melting point and crystallization temperature. The glass transition temperature Tg was calculated from the DSC curve observed during the second heating process using the analysis software attached to the instrument to determine the midpoint glass transition temperature. This midpoint glass transition temperature was determined from the relevant standard (9.3). The glass transition temperature (Tg) was determined by using the Tg at a temperature lower than the crystallization peak observed during the second heating process, as seen in the differential scanning calorimetry (DSC) chart (DC curve) at a heating rate of 10°C / min. However, if no crystallization peak was observed during the second heating process, the glass transition temperature (Tg) within the temperature range of the second heating process (30-300°C) was used.

[0161] <Endothermic amount (a), Exothermic amount (b), Degree of crystallinity> The endothermic (a) (heat of fusion) and exothermic (b) (heat of crystallization) were measured using the methods described in JIS K7121:1987 and JIS K7121:2012. However, the sampling method and temperature conditions were as follows. Samples cut from foamed particles or molded foamed particles were packed tightly into the bottom of an aluminum measuring container at a concentration of 5.5 ± 0.5 mg, and then the aluminum lid was placed over them. Differential scanning calorimetry was then performed using a Hitachi High-Tech Science Corporation "DSC7000X, AS-3" differential scanning calorimetry meter. Under a nitrogen gas flow rate of 20 mL / min, the samples were heated and cooled in the following steps 1-2 to obtain DSC curves. (Step 1) Hold at 30°C for 2 minutes. (Step 2) Heat from 30°C to 300°C at a rate of 10°C / min (first heating process). Alumina was used as the reference material in this experiment. The endothermic (a) and exothermic (b) values ​​were calculated using the analysis software provided with the device. Specifically, as shown in Figure 4, the endothermic (a) value was calculated from the area enclosed by the straight line connecting the point where the DSC curve deviates from the low-temperature baseline and the point where the DSC curve returns to the high-temperature baseline, and the DSC curve itself. The exothermic (b) value was calculated from the area enclosed by the straight line connecting the point where the DSC curve deviates from the low-temperature baseline and the point where the DSC curve returns to the high-temperature baseline, and the DSC curve itself. The degree of crystallinity is determined by the following method. First, the difference between the heat absorbed (a) and the heat released (b) is calculated. The degree of crystallinity is determined by dividing this difference by the theoretical heat of fusion of polyethylene terephthalate perfect crystals, which is 140.1 J / g. In other words, the degree of crystallinity is determined by the following equation (s4). Crystallinity (%) = (endotherm (a) (J / g) - calorific value (b) (J / g)) / 140.1 (J / g) × 100 (s4)

[0162] <Phosphorus content> The phosphorus content of foamed particles or molded foamed particle products was determined by the order of analysis method of X-ray fluorescence analysis. Using a Rigaku Corporation "ZSX PrimusIV" X-ray fluorescence analyzer, the phosphorus intensity was measured under the following conditions, and the phosphorus content relative to the total mass of the thermoplastic resin was determined by the order of analysis method. Approximately 0.5 g of the sample to be measured was formed into a thin film using a hot press molding machine, placed in the 30 mmφ sample case attached to the instrument, and used as the measurement sample.

[0163] ≪Device Conditions≫ · Device: ZSX PrimusIV. · X-ray tube target: Rh. · Measurement diameter: 30 mm. · Spin: None. · Atmosphere: Vacuum. · Sample form: Metal. · Balance components: C 30 H 23 O8N. · Sample film: None. · Sample weight thickness: To be set ≪Qualitative Element Conditions≫ · P-Kα. · Tube: Rh (30 kV - 100 mA). · Filter: Be30. · Attenuator: 1 / 1. · Slit: S4. · Spectroscopic crystal: GeH. · 2θ: 141.2 deg (measurement range: 137 - 144 deg). · Detector: PC. · PHA: 150 - 300. · Step: 0.05 deg. · Time: 0.15 sec.

[0164] <Flammability> Flammability was measured according to the method described in the vertical combustion test (V) described in UL94:1996. From the foamed molded body formed into a size of 300 mm in length × 400 mm in width × 11 mm in height from foamed particles, a test piece with a length of 125 mm × a width of 13 mm × a thickness of 11 mm (with a skin layer only in the thickness direction) was cut out and used for measurement. The test piece was conditioned under the conditions of ASTM D618 and then used for measurement. The measurement was carried out in an environment of a temperature of 10 - 35°C and a humidity of 45 - 75%, and the flammability was evaluated according to the description of the vertical combustion test (V) described in UL94:1996.

[0165] ≪Evaluation Criteria≫ A: The result of the combustion test is V-0. B: The result of the combustion test is V-1. C: The result of the combustion test is V-2. D: The result of the combustion test is not V-0 to V-2 (non-compliant).

[0166] <Rate of dimensional change upon heating (heat resistance)> The rate of dimensional change upon heating of the expanded particle molded body was measured by Method B described in JIS K6767:1999 "Expanded Plastics - Polyethylene - Test Methods". A test piece with a square planar shape having a side length of 150 mm and a thickness equal to the thickness of the expanded particle molded body was cut out from the expanded particle molded body. Three 100-mm straight lines parallel to each other were marked at 50-mm intervals in the longitudinal and transverse directions at the center of the test piece. The lengths of the three straight lines in the longitudinal and transverse directions were measured respectively, and their arithmetic mean value L0 was taken as the initial dimension. Then, the test piece was placed in a hot air circulation dryer set at 180°C for 168 hours to conduct a heating test. After the heating test, the test piece was taken out and left at 25°C for 1 hour. Next, the lengths of the three straight lines in the longitudinal and transverse directions marked on the surface of the test piece were measured respectively, and their arithmetic mean value L1 was taken as the dimension after heating. The rate of dimensional change upon heating was calculated based on the following formula (s5). Rate of dimensional change upon heating (%) = 100 × |(L1 - L0)| / L0 ··· (s5) Based on the results of measuring the rate of dimensional change upon heating of the expanded particle molded body at each set temperature, the following criteria were used for evaluation.

[0167] ≪Evaluation Criteria≫ A: The rate of dimensional change upon heating is less than 1.0%. B: The rate of dimensional change upon heating is 1.0% or more and less than 2.0%. C: The rate of dimensional change upon heating is 2.0% or more.

[0168] <Moldability> The surface of the expanded particle molded body was visually inspected and evaluated according to the following criteria.

[0169] ≪Evaluation Criteria≫ A: There are no gaps between the expanded particles, the surface of the molded body is very smooth, and the appearance of the molded body is very good. B: There are very few gaps between the expanded particles, the surface of the molded body is almost smooth, and the appearance of the molded body is good. C: The gaps between foam particles are small, resulting in small irregularities on the surface of the molded product, and the appearance of the molded product is somewhat inferior. D: There are numerous gaps between the foam particles, resulting in large irregularities on the surface of the molded product, or significant shrinkage is observed during molding, resulting in a significantly inferior appearance of the molded product.

[0170] <Overall Rating> The results of evaluations for moldability, dimensional change rate upon heating, combustion test, and flame retardancy were classified according to the following evaluation criteria.

[0171] ≪Evaluation Criteria≫ A: In all evaluations, the rating was "A". B: In each evaluation, the rating was either "A" or "B", with at least one rating being "B". C: In each evaluation, the rating was either "A", "B", or "C", with at least one rating being "C". D: At least one rating in each evaluation was "D".

[0172] (Example 1) Using a manufacturing apparatus similar to the foamed particle manufacturing apparatus 10 shown in Figures 4-6, foamed particles were produced according to the following procedure. First, according to the formulations shown in the table, polyester resin, polyimide resin, phosphorus-based flame retardant, talc masterbatch, and crosslinking agent were supplied to a single-screw extruder with a cylinder bore diameter D of 65 mm and an L (cylinder length) / D (cylinder bore) ratio of 34, and these were melted and kneaded at 290°C. Next, butane (isobutane:n-butane = 35:65 (mass ratio)) was injected into the molten mixture as a foaming agent from the middle of the extruder in the amount shown in the table, and uniformly dispersed in the molten mixture to form a resin composition. After that, the molten resin composition was heated to 300°C at the front end of the extruder, and the resin composition was extruded and foamed from each nozzle of a multi-nozzle type nozzle mold 1 attached to the front end of the extruder. The extrusion rate of the resin composition was 36 kg / h. The nozzle mold 1 had 50 nozzles, each with an outlet diameter of 0.8 mm, and all of the outlets 11 were positioned at equal intervals on a virtual circle A with a diameter of 139.5 mm. Two rotating blades 5 were integrally mounted on the outer circumferential surface of the rear end of the rotating shaft 2 with a phase difference of 180° in the circumferential direction of the rotating shaft 2, and each rotating blade 5 was configured to move on the virtual circle A while constantly in contact with the front end surface 1a of the nozzle mold 1.

[0173] The cooling member 4 comprised a cooling drum 41 consisting of a front circular portion 41a and a cylindrical peripheral wall portion 41b extending rearward from the outer edge of the front portion 41a with an inner diameter of 320 mm. Cooling liquid 42 at 20°C was supplied into the cooling drum 41 through a supply pipe 41d and a supply port 41c of the cooling drum 41. The volume inside the cooling drum 41 was 17684 cm³. 3 That was the case. The coolant 42, supplied from the supply pipe 41d to the inner surface of the peripheral wall 41b of the cooling drum 41, was propagated forward in a spiral pattern along the inner surface of the peripheral wall 41b of the cooling drum 41 by the centrifugal force associated with its flow velocity. As the coolant 42 advanced along the inner surface of the peripheral wall 41b, it gradually spread in a direction perpendicular to the direction of travel, completely covering the inner surface of the peripheral wall 41b in front of the supply port 41c of the cooling drum 41.

[0174] A rotating blade 5, positioned on the front end surface 1a, was rotated at a speed of 3400 rpm. The extruded foam, which was extruded and foamed from the outlet 11 of each nozzle of the nozzle mold 1, was cut by the rotating blade 5 to produce roughly spherical granular cut pieces. The extruded foam consisted of an unfoamed portion immediately after being extruded from the nozzle of the nozzle mold 1, and a foamed portion that was in the process of foaming, which was continuous with the unfoamed portion. The extruded foam was cut at the open end of the nozzle outlet 11, and the cutting of the extruded foam took place in the unfoamed portion. In the production of the foamed particles described above, first, the rotating shaft 2 was not attached to the nozzle mold 1, and the cooling member 4 was retracted from the nozzle mold 1. In this state, the resin composition was extruded from the extruder to form an extruded foam, and it was confirmed that it consisted of an unfoamed portion immediately after being extruded from the nozzle of the nozzle mold 1, and a foamed portion in the process of foaming that was continuous with this unfoamed portion. Next, the rotating shaft 2 was attached to the nozzle mold 1 and the cooling member 4 was placed in a predetermined position, and then the rotating shaft 2 was rotated to cut the extruded foam with the rotating blade 5 at the opening end of the nozzle outlet 11 to produce particulate cut material.

[0175] These particulate pieces are propelled outward or forward by the cutting stress from the rotating blade 5, and collide with the coolant 42 flowing along the inner surface of the cooling drum 41 of the cooling member 4, from an oblique direction to the surface of the coolant 42, following the coolant 42 flow from upstream to downstream. The particulate pieces enter the coolant 42 and are immediately cooled, producing foamed particles. The resulting foamed particles were discharged together with the coolant 42 through the outlet 41e of the cooling drum 41, and then separated from the coolant 42 in a dewatering machine.

[0176] An in-mold foam molding machine equipped with molds (male and female) was prepared. Two types of molds were used depending on the evaluation criteria. The two types of molds are: Mold A, in which a rectangular prism-shaped cavity with internal dimensions of 300mm (length) x 400mm (width) x 30mm (height) is formed between the male and female molds when they are clamped together; and Mold B, in which a rectangular prism-shaped cavity with internal dimensions of 300mm (length) x 400mm (width) x 11mm (height) is formed. In mold A, foam particles were filled into the mold with a 3mm mold cracking. In mold B, foam particles were filled into the mold with a 1mm mold cracking. After filling the mold with foam particles, steam was introduced from the female mold for 60 seconds to bring the cavity pressure to 0.30 MPa (gauge pressure) (one-sided heating), then steam was introduced from the male mold for 45 seconds to bring the cavity pressure to 0.30 MPa (gauge pressure) (reverse one-sided heating), and then steam was supplied from both the male and female molds for 60 seconds to bring the cavity pressure to 0.33 MPa (gauge pressure) (double-sided heating), heating the foam particles and causing secondary foaming, which then thermally fused the secondary foam particles together to form a single mass. After that, the introduction of steam into the cavity was stopped and the mixture was held for 110 seconds (heat retention process), and finally, a cooling liquid was supplied into the cavity to cool the foam particle molded body inside the mold, after which the cavity was opened and the foam particle molded body was removed. The moldability and dimensional change rate upon heating were evaluated for the foam particle molded product formed with mold A. The combustion test and flame retardancy were evaluated for the foam particle molded product formed with mold B. A comprehensive evaluation was conducted based on these results, and the results are shown in the table.

[0177] (Examples 2-20, Comparative Examples 1-4) Foamed particles and foamed particle molded articles were prepared in the same manner as in Example 1, except that the polyester resin, polyimide resin, talc masterbatch, phosphorus-based flame retardant, crosslinking agent, and blowing agent were as shown in the table, and the molding conditions were as shown in Tables 2 to 7. The obtained foamed particles or foamed particle molded articles were subjected to moldability, dimensional change rate upon heating, combustion tests, flame retardancy evaluation, and overall evaluation, and the results are shown in the table. Note that for Comparative Examples 3 and 4, the moldability was "D," and no foamed particle molded articles suitable for evaluation could be obtained; therefore, dimensional change rate upon heating, combustion tests, and flame retardancy evaluation were not performed.

[0178] [Table 2]

[0179] [Table 3]

[0180] [Table 4]

[0181] [Table 5]

[0182] [Table 6]

[0183] [Table 7]

[0184] Examples 1 to 20 to which the present invention was applied showed combustion test results of V-0 to V-2, and overall evaluations of "A" to "C". Comparative Examples 1 and 2, which did not contain phosphorus-based flame retardants, failed the combustion test and received a flame retardancy rating of "D". Comparative Example 3, which had a phosphorus content of 1.32% by mass, and Comparative Example 4, which had a polyimide resin content of 50% by mass relative to the total mass of thermoplastic resin, both had a moldability rating of "D". From the above results, it was confirmed that by applying the present invention, flame retardancy and heat resistance can be improved, and the moldability of the foamed particle molded article can be enhanced.

[0185] Furthermore, for the thermoplastic resin foam particles obtained in Examples 1, 3, and 6, the polyimide resin content relative to the total mass of the thermoplastic resin was measured using the method described in "[Method for Measuring the Content Ratio of Polyimide Resin]" above. The results are shown in Table 8.

[0186] [Table 8] [Explanation of Symbols]

[0187] 100 Foamed resin composite 102 Foamed particle molded body 104 Fiber-reinforced resin layer

Claims

1. Contains thermoplastic resin, The thermoplastic resin comprises a polyester resin, a polyimide resin, and a phosphorus-based flame retardant. The content of the polyimide resin is 5 to 45% by mass relative to the total mass of the thermoplastic resin. The phosphorus content is 0.15 to 1.00% by mass relative to the total mass of the thermoplastic resin. Thermoplastic resin foam particles with a glass transition temperature Tg of 80 to 130°C.

2. The thermoplastic resin foam particles according to claim 1, wherein the content of the polyimide resin is 25 to 45% by mass relative to the total mass of the thermoplastic resin.

3. It consists of two or more thermoplastic resin foam particles that are heat-fused together. Contains thermoplastic resin, The thermoplastic resin comprises a polyester resin, a polyimide resin, and a phosphorus-based flame retardant. The content of the polyimide resin is 5 to 45% by mass relative to the total mass of the thermoplastic resin. The phosphorus content is 0.15 to 1.00% by mass relative to the total mass of the thermoplastic resin. A thermoplastic resin foam particle molded body with a glass transition temperature Tg of 80 to 130°C.

4. The thermoplastic resin foam particle molded article according to claim 3, wherein the flame retardancy measured in accordance with the UL-94 vertical method (11 mm vertical combustion test) of the UL standard is V-0, V-1, or V-2.

5. The thermoplastic resin foam particle molded article according to claim 3, wherein the content of the polyimide resin is 25 to 45% by mass with respect to the total mass of the thermoplastic resin.

6. The thermoplastic resin foam particle molded article according to claim 5, wherein the flame retardancy measured in accordance with the UL-94 vertical method (11 mm vertical combustion test) of the UL standard is V-0 or V-1.

7. A foamed resin composite comprising a thermoplastic resin foam particle molded body according to any one of claims 3 to 6, and a fiber-reinforced resin layer provided on at least a portion of the surface of the thermoplastic resin foam particle molded body.

8. The process includes a step of extruding and foaming a thermoplastic resin composition containing a thermoplastic resin and a foaming agent to obtain thermoplastic resin foam particles. The thermoplastic resin comprises a polyester resin, a polyimide resin, and a phosphorus-based flame retardant. The content of the polyimide resin is 5 to 45% by mass relative to the total mass of the thermoplastic resin. A method for producing foamed thermoplastic resin particles according to claim 1, wherein the phosphorus content is 0.15 to 1.00% by mass with respect to the total mass of the thermoplastic resin.

9. The method for producing foamed thermoplastic resin particles according to claim 8, wherein the content of the polyimide resin is 25 to 45% by mass with respect to the total mass of the thermoplastic resin.

10. A method for producing a molded article of thermoplastic resin foam particles, comprising: obtaining thermoplastic resin foam particles by the method for producing thermoplastic resin foam particles described in claim 8 or 9; filling the obtained thermoplastic resin foam particles into a cavity of a mold; heating the thermoplastic resin foam particles in the cavity to form secondary foam particles; and heat-fusing the secondary foam particles together to obtain a molded article of thermoplastic resin foam particles.

11. A battery case or battery case comprising a thermoplastic resin foam particle molded body according to any one of claims 3 to 6.

Images