Amide-based elastomer foam particles, amide-based elastomer foam molded article, and method for producing said foam molded article

Abstract

The purpose of the present invention is to provide: an amide-based elastomer foam molded body having light weight and high resilience and / or softness; and amide-based elastomer foam particles for producing the foam molded body. The present invention relates to an amide-based elastomer foamed particle containing an amide-based elastomer resin as a base resin, the foamed particle containing 50-100 mass% of the amide-based elastomer resin, the amide-based elastomer resin having a Shore D hardness of 40 or less, and the amide-based elastomer resin having a Shore D hardness of 40 or less. The amide elastomer resin is characterized in that the complex viscosity value obtained by dynamic viscoelasticity measurement under temperature dispersion conditions is subjected to first-order differential processing, the minimum value is determined from the obtained differential value, the absolute value of the minimum value is 1.0 E + 05 or less, and the temperature at the minimum value is 134 DEG C or less.

Description

Technical Field

[0001] The present invention relates to: amide elastomer foamed particles containing an amide elastomer resin as a base resin; a lightweight and highly resilient amide elastomer foamed molded body containing an amide elastomer resin as a base resin; and a method for producing the foamed molded body. Background Art

[0002] Resin foam moldings are generally used as cushioning materials and packaging materials. Here, the foam molding is manufactured by heating and foaming (pre-foaming) foamable particles made of resin to obtain foam particles (pre-foam particles), filling the obtained foam particles into a mold cavity, performing secondary foaming, and integrating the foam particles with each other by heat fusion, thereby manufacturing.

[0003] Elastomers have excellent rebound resilience and high mechanical strength, and therefore are positioned as engineering elastomers, and are studied for use in various applications such as daily necessities, electrical and chemical product parts, sporting goods, automotive parts, and building and civil engineering components. It is expected that the molded body formed by foaming the elastomer will be lightweight and have the high rebound resilience inherent in the elastomer, and therefore, methods of welding and foaming foamed particles prepared from an elastomer resin in a mold and molding the same have been reported (e.g., Patent Documents 1 and 2).

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application No. 2019-510840

[0007] Patent Document 2: Japanese Patent Application No. 2019-518859 Summary of the invention

[0008] Problem that the invention aims to solve

[0009] The density of the foamed molded product described in Patent Documents 1 and 2 is 0.2 g / cm 3 Therefore, it cannot be said that the foam molded product is light, and a lighter elastomer foam molded product is desired.

[0010] The maximum rebound resilience ratio of the foamed molded article described in Patent Document 1 is 66%, which does not mean that the rebound resilience inherent in the elastomer is fully utilized. Therefore, an elastomer foamed molded article having higher rebound resilience is desired.

[0011] In addition, if the foamed molded article is hard, it becomes difficult to use it in applications requiring cushioning properties, and therefore, a softer foamed molded article is desired.

[0012] Solutions for solving problems

[0013] The inventors of the present invention have conducted intensive research to solve at least one of the above problems, and have found that an amide elastomer foamed molded product that is not too hard, is lightweight, and has a high resilience can be obtained by foaming foamed particles containing a soft amide elastomer that shows specific properties in dynamic viscoelasticity measurement as a base resin in a mold. The present invention is based on the above findings, and a representative embodiment of the present invention is as follows.

[0014] Item 1.

[0015] A foamed particle, which is an amide elastomer foamed particle containing an amide elastomer resin as a base resin,

[0016] The foamed particles contain 50 to 100% by mass of the amide elastomer resin.

[0017] The amide elastomer resin has a Shore D hardness of 40 or less.

[0018] The above-mentioned amide elastomer resin is as follows: the complex viscosity value obtained in the dynamic viscoelasticity measurement under temperature dispersion conditions is subjected to first-order differential processing, and the minimum value is determined from the obtained differential value. The absolute value of the minimum value is less than 1.0E+05, and the temperature at the minimum value is less than 134°C.

[0019] Item 2.

[0020] The foamed beads according to item 1, wherein the amide elastomer resin has a polyamide block as a hard segment and a polyether block as a soft segment.

[0021] Item 3.

[0022] The foamed beads according to item 1 or 2, wherein the amide elastomer resin has a Shore D hardness of 38 or less.

[0023] Item 4.

[0024] The expanded beads according to any one of items 1 to 3, wherein the absolute value of the local minimum value is 8.0E+04 or less.

[0025] Item 5.

[0026] The expanded beads according to any one of items 1 to 4, wherein the temperature at the minimum value is 133° C. or lower.

[0027] Item 6.

[0028] A foamed molded product, which is an amide elastomer foamed molded product using an amide elastomer resin as a base resin, wherein the foamed molded product contains 50 to 100% by mass of the amide elastomer resin.

[0029] The amide elastomer resin has a Shore D hardness of 40 or less.

[0030] The above-mentioned amide elastomer resin is as follows: the complex viscosity value obtained in the dynamic viscoelasticity measurement under temperature dispersion conditions is subjected to first-order differential processing, and the minimum value is determined from the obtained differential value. The absolute value of the minimum value is less than 1.0E+05, and the temperature at the minimum value is less than 134°C.

[0031] Item 7.

[0032] The foamed molded product according to item 6, wherein the amide elastomer resin has a polyamide block as a hard segment and a polyether block as a soft segment.

[0033] Item 8.

[0034] The foamed molded product according to item 6 or 7, wherein the amide elastomer resin has a Shore D hardness of 38 or less.

[0035] Item 9.

[0036] The foamed molded product according to any one of Items 6 to 8, wherein the absolute value of the local minimum value is 8.0E+04 or less.

[0037] Item 10.

[0038] The foamed molded product according to any one of Items 6 to 9, wherein the temperature at the minimum value is 133° C. or less.

[0039] Item 11.

[0040] The foamed molded product according to any one of Items 6 to 10, wherein the rebound resilience is 70% or more.

[0041] Item 12.

[0042] The foamed molded product according to any one of items 6 to 11, wherein the density is 0.20 g / cm 3 the following.

[0043] Item 13.

[0044] The foamed molded product according to any one of Items 6 to 12, wherein the Asker C hardness is 38 or less.

[0045] Item 14.

[0046] A method for producing a foamed molded article, comprising filling the foamed beads according to any one of claims 1 to 5 into a mold, heating the mold and foaming the molded article.

[0047] Effects of the Invention

[0048] According to the present invention, there can be provided: an amide elastomer foam molded product which is not too hard, is lightweight, and has a high resilience; foamed particles useful in producing the foam molded product; and a method for producing an amide elastomer foam molded product using the foamed particles. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 The following table shows the results of dynamic viscoelasticity measurement of the base resin under temperature dispersion conditions. The horizontal axis represents temperature (° C.) and the vertical axis represents complex viscosity (Pa·s).

[0050] Figure 2 Show Figure 1 The complex viscosity value and the value obtained by first-order differentiation of the complex viscosity value are shown. The horizontal axis represents temperature (°C), the left vertical axis represents complex viscosity (Pa·s), and the right vertical axis represents the value obtained by first-order differentiation.

[0051] Figure 3 A scatter plot based on the temperature (horizontal axis (° C.)) at the minimum value of the first-order differential value confirmed in Examples and Comparative Examples and the absolute value (vertical axis) of the minimum value when the first-order differential of the complex viscosity value is taken is shown. DETAILED DESCRIPTION

[0052] (1) Amide elastomer foam particles

[0053] Amide elastomer foamed particles (sometimes referred to as "foamed particles" in this specification) contain an amide elastomer resin as a base resin. The content of the amide elastomer resin in the foamed particles can be, for example, 50 to 100 mass %, 70 to 100 mass %, preferably 80 to 100 mass %, and more preferably 90 to 100 mass % relative to the mass of the foamed particles. The amide elastomer resin can be used alone or in combination of two or more.

[0054] The amide-based elastomer resin is preferably a copolymer resin having a polyamide block as a hard segment and a polyether block as a soft segment.

[0055] Examples of the polyamide block constituting the hard segment include polyamide structures such as polycondensation polyamides derived from ε-caprolactam, 11-aminoundecanoic acid, 12-aminolauric acid, and the like, and co-condensation polyamides of dicarboxylic acids such as adipic acid, sebacic acid, terephthalic acid, and isophthalic acid and diamines such as hexamethylenediamine, nonanediamine, and methylpentanediamine. The polyamide block may also be a combination of units constituting these polyamide structures.

[0056] Examples of the polyether block constituting the soft segment include polyether structures derived from polyethylene glycol, polypropylene glycol, polytetramethylene glycol, etc. The polyether block may be a combination of units constituting these polyether structures.

[0057] The polyamide blocks and the polyether blocks may be randomly dispersed.

[0058] As the block copolymer resin, from the viewpoint of reducing environmental load and improving the resilience of the foamed molded article, a block copolymer resin derived from castor oil is preferred, and more preferably, a plant-derived resin (castor oil-derived polyamide 11) in which 11-aminoundecanoic acid obtained from castor oil is used for the formation of the polyamide block is used. In addition, when 11-aminoundecanoic acid obtained from castor oil is used for the formation of the polyamide block, from the viewpoint of improving the resilience of the foamed molded article, polytetramethylene glycol is preferably used for the formation of the polyether block.

[0059] By using an amide elastomer resin having a specific viscoelastic behavior under temperature dispersion conditions as a base resin, a lightweight foamed molded product with high resilience can be produced. For example, the following amide elastomer resin can be used: a complex viscosity value obtained in a dynamic viscoelasticity measurement under temperature dispersion conditions is subjected to first-order differential processing, a minimum value is determined from the obtained differential value, the absolute value of the minimum value is 1.0E+05 or less, and the temperature showing the minimum value is 134°C or less.

[0060] (Minimum value)

[0061] The absolute value of the minimum value may be, for example, 1.0E+05 or less (100,000 or less), preferably 9.0E+04 or less (90,000 or less), more preferably 8E+04 or less (80,000 or less), and further preferably 7.5E+04 or less (75,000 or less). The absolute value of the minimum value may be, for example, 0.0E+00 or more, 1.0E+02 or more, etc. The absolute value of the minimum value may be, for example, 0.0E+00 to 1.0E+05, 0.0E+00 to 9.0E+04, 0.0E+00 to 8.0E+04, 0.0E+00 to 7.5E+04, 1.0E+02 to 1.0E+05, 1.0E+02 to 9.0E+04, 1.0E+02 to 8.0E+04, 1.0E+02 to 7.5E+04, etc.

[0062] The temperature at the minimum value may be, for example, 134°C or less, preferably 133°C or less, more preferably 132°C or less, further preferably 130°C or less, and most preferably 127°C or less. The temperature at the minimum value may be, for example, 65°C or more, 70°C or more, 75°C or more, etc. The temperature at the minimum value may be 65°C to 134°C, 70°C to 134°C, 75°C to 134°C, 65°C to 133°C, 70°C to 133°C, 75°C to 133°C, 65°C to 132°C, 70°C to 132°C, 75°C to 132°C, 65°C to 130°C, 70°C to 130°C, 75°C to 130°C, 65°C to 127°C, 70°C to 127°C, 75°C to 127°C, etc.

[0063] By using an amide elastomer resin having a minimum absolute value and a temperature at the minimum value within the above range as the base resin, a foamed molded product that is lightweight and has high resilience can be produced as described above.

[0064] The minimum value can be determined as follows. The amide elastomer resin is subjected to a dynamic viscoelasticity measurement under temperature dispersion conditions to obtain a complex viscosity value. The obtained complex viscosity value is subjected to a first-order differential to obtain a first-order differential value. A graph is prepared with the first-order differential value as the vertical axis and the temperature as the horizontal axis (e.g. Figure 2 ) is the minimum value. For example, Figure 2 The minimum value in Example 1 is 68541, and the temperature showing the minimum value is 82°C.

[0065] (Determination of complex viscosity)

[0066] Complex viscosity can be measured according to JIS K 7244-1. For example, it can be determined as follows. The resin to be the sample is pressed in a hot press to make a disc-shaped sample with a diameter of 25 mm and a thickness of 3 mm. Next, the plate of a dynamic viscoelasticity measuring device (for example, PHYSICAMCR301 (manufactured by Anton Paar)) is heated to 220°C, the sample is set on the heated plate, and heated for 5 minutes under a nitrogen atmosphere to melt the sample. The gap between the plates is set to 2.0 mm, the exuded resin is removed, and the measurement is started 5 minutes after the measurement temperature is reached ±1°C. The measurement conditions are set to a frequency of 1 Hz, a strain of 1%, a normal force of ON, a temperature of 220 to 50°C or a temperature of 220 to 80°C (the cooling rate is 2°C / minute), and the complex viscosity is measured.

[0067] (Calculation of the first-order differential value of complex viscosity)

[0068] The complex viscosity values ​​at various temperatures obtained by measuring the complex viscosity are subjected to first-order differential processing to obtain the minimum value and absolute value of the first-order differential value. Specifically, the difference in complex viscosity values ​​at intervals of 5°C is divided by 5°C to obtain the minimum value and the absolute value of the first-order differential value. It should be noted that this processing can be performed on EXCEL. From the first-order differential value of the complex viscosity as a function of temperature, the absolute value of the minimum value and the temperature at which the minimum value is shown can be obtained.

[0069] The biobased content of the amide elastomer resin measured by ASTM D6866 can be, for example, 30% or more, 40% or more, 30 to 80%, etc., preferably 40 to 80%, more preferably 40 to 70%. If the biobased content is within the above range, the biobased content of the foamed molded article can be increased and the reduction in the rebound rate can be suppressed.

[0070] (Shore D hardness of amide elastomer resin)

[0071] For amide elastomer resin, if its hardness is low, a soft foaming molded product can be produced, which is preferable. The Shore D hardness of the amide elastomer resin can be set to 40 or less, preferably 38 or less, more preferably 37 or less, and further preferably 35 or less. The Shore D hardness of the amide elastomer resin can be set to, for example, 25 to 40, 25 to 38, 25 to 37, 25 to 35, 30 to 40, 30 to 38, 30 to 37, 30 to 35, etc. The Shore D hardness of the amide elastomer resin can be determined according to ISO868.

[0072] The melting point (ISO 11357) of the amide elastomer resin is preferably 70°C to 160°C, more preferably 80°C to 150°C.

[0073] The melt mass flow rate (MFR) of the amide elastomer resin can be, for example, 20 to 50 g / 10 min, preferably 30 to 50 g / 10 min, more preferably 35 to 45 g / 10 min.

[0074] The base resin may contain other resins, such as other amide resins, polyether resins, styrene elastomers, olefin elastomers, ester elastomers, etc., in addition to the amide elastomer resin, within a range not impairing the effects of the present invention.

[0075] The substrate particles may contain a flame retardant, a colorant, an antistatic agent, a spreading agent, a plasticizer, a crosslinking agent, a filler, a lubricant, etc. in addition to the substrate resin.

[0076] Examples of the flame retardant include hexabromocyclododecane and triallyl isocyanurate hexabromide.

[0077] Examples of the colorant include inorganic pigments such as carbon black, graphite, iron oxide, and titanium oxide; organic pigments such as phthalocyanine blue, quinacridone red, and isoindolinone yellow; special pigments such as metal powder and pearls; and dyes.

[0078] Examples of the antistatic agent include polyoxyethylene alkylphenol ether and stearic acid monoglyceride.

[0079] Examples of the spreading agent include polybutene, polyethylene glycol, and silicone oil.

[0080] The foamed particles preferably have a particle size of 0.015 g / cm 3 ~0.5g / cm 3 The preferred volume density is 0.02 g / cm 3 ~0.3g / cm 3 , and a further preferred bulk density is 0.05 g / cm 3 ~0.2g / cm 3 .

[0081] The shape of the expanded beads is not particularly limited, and examples thereof include spherical, ellipsoidal (oval), cylindrical, prism-shaped, pellet-shaped, or granular shapes.

[0082] The average particle size of the foamed particles is not limited as long as the desired foamed molded article can be obtained, preferably 1 mm to 10 mm, more preferably 2 mm to 10 mm. If the average particle size is within the above range, the foamed particles are easy to manufacture, the secondary foaming property during molding is not easy to decrease, the filling property of the mold is not easy to decrease when the foamed molded article is made by heating and foaming, and it is also easy to manufacture a foamed molded article with a complex shape.

[0083] The expanded particles are useful as a raw material for producing a lightweight and resilient expanded molded article.

[0084] The expanded beads can be used as a raw material for a foamed molded body for foaming in a mold, or can be used directly as a cushioning filler, for example.

[0085] (2) Amide-based elastomer foamed molded product

[0086] The polyamide elastomer foam molding (sometimes referred to as "foam molding" in this specification) contains, for example, 50 to 100% by mass of an amide elastomer resin. Regarding the details of the amide elastomer resin in the polyamide elastomer foam molding, the above description about the amide elastomer resin can be applied. The amide elastomer resin preferably has a Shore D hardness of 40 or less. The amide elastomer resin is preferably as follows: the complex viscosity value obtained in the dynamic viscoelasticity measurement under temperature dispersion conditions is subjected to first-order differential processing, and a minimum value is determined from the obtained differential value, the absolute value of the minimum value is less than 1.0E+05, and the temperature at the minimum value is less than 134°C.

[0087] The foamed molded product is preferably composed of a fused body of a plurality of foamed beads formed by foam-molding the foamed beads in a mold.

[0088] The foamed article contains, for example, 50 to 100% by mass, 70 to 100% by mass, preferably 80 to 100% by mass, and more preferably 90 to 100% by mass of the amide elastomer resin. If the content of the amide elastomer resin is within the above range, the foamed article is lightweight and has a high resilience. The amide elastomer resin may be used alone or in combination of two or more.

[0089] The foamed molded product may contain two or more of the above-mentioned amide elastomer resins having different bio-based contents, or may contain a resin having a bio-based content of 0%.

[0090] The foamed molded product may contain other resins, such as other amide resins, polyether resins, styrene elastomers, olefin elastomers, ester elastomers, etc., in addition to the above-mentioned amide elastomer resins within a range not impairing the effects of the present invention.

[0091] The foamed molded product may further contain a flame retardant, a colorant, an antistatic agent, a spreading agent, a plasticizer, a crosslinking agent, a filler, a lubricant, and the like within a range not impairing the effects of the invention.

[0092] The foamed molded article has a high rebound rate by including the aforementioned amide elastomer resin or by being produced from the aforementioned foamed particles. The rebound rate is, for example, 70% or more, 71% or more, 72% or more, 73% or more, and preferably 75% or more. The rebound rate can be, for example, 70-95%, 71-95%, 72-95%, 73-95%, 75-95%, etc.

[0093] The foamed molded article contains the aforementioned amide elastomer resin or is produced from the aforementioned foamed particles, so that the foamed molded article is lightweight as an elastomer. The density of the foamed molded article is, for example, 0.20 g / cm 3 Below, preferably 0.18g / cm3 Below, more preferably 0.17g / cm 3 The density can be 0.05 to 0.20 g / cm 3 , 0.08~0.18g / cm 3 , 0.10~0.17g / cm 3 wait.

[0094] The foamed molded article is soft as an elastomer foamed molded article by including the aforementioned amide elastomer resin or by being manufactured from the aforementioned foaming particles. The Asker C hardness of the foamed molded article is, for example, 42 or less, 41 or less, 39 or less, etc., preferably 38 or less, more preferably 37 or less, and further preferably 35 or less. The Asker C hardness may be 23 to 42, 23 to 41, 23 to 39, 23 to 38, 23 to 37, 23 to 35, 25 to 42, 25 to 41, 25 to 39, 25 to 38, 25 to 37, 25 to 35, 27 to 35, etc.

[0095] The foamed molded body can be used, for example, in the industrial field, sports goods, cushioning materials, core materials of beds, cushions (seat cushions, etc.), automotive components (automotive interior materials, etc.), etc. In particular, it can be used for applications that require reduced environmental load and improved resilience. For example, it can be used for midsole components, inner bottom components or outer bottom components of leather shoes; core materials of hitting tools such as rackets and bats for sports goods; protective gear for sports goods such as pads and protective gear; medical, nursing, welfare or health care products such as pads and protective gear; tire core materials for bicycles, wheelchairs, etc.; interior materials, seat core materials, impact absorbing components, vibration absorbing components, etc. for transportation equipment such as automobiles, railway vehicles, and airplanes; fenders; floating boats; toys; floor base materials; wall materials; beds; mats; electronic components, various industrial materials, food, etc., etc., etc.

[0096] The foamed molded body can take an appropriate shape depending on the above-mentioned use.

[0097] (3) Method for producing polyamide elastomer foamed particles

[0098] The foamed particles filled into the mold can be obtained through the following steps: a step of impregnating the particles of the aforementioned base resin with a foaming agent to obtain foamed particles (impregnation step); a foaming step of foaming the foamed particles; and a further step of imparting internal pressure to the foamed particles to contain an inorganic gas as required.

[0099] (Impermeation process)

[0100] (a) Resin particles

[0101] The resin pellets can be obtained using a known manufacturing method and manufacturing equipment. For example, the melt-kneaded product of the base resin extruded from the extruder is pelletized by underwater cutting, strand cutting, etc., so that the resin pellets can be produced. The temperature, time, pressure, etc. during melt kneading can be appropriately set according to the raw materials used and the manufacturing equipment.

[0102] The melt-kneading temperature in the extruder during melt-kneading is the temperature at which the base resin is fully softened. Therefore, it can be appropriately set according to the resin used. It is preferably 140°C to 190°C, and more preferably 150°C to 180°C. The melt-kneading temperature refers to the temperature of the melt-kneaded material inside the extruder obtained by measuring the temperature of the center of the melt-kneading flow path near the extruder head with a thermocouple thermometer.

[0103] The shape of the resin particles is, for example, spherical, ellipsoidal (oval), cylindrical, prism-shaped, pellet-shaped, or granular.

[0104] The resin particles preferably have a length L and an average diameter D of 0.8 to 3. When the L / D of the resin particles is within this range, the filling property in the mold is good. It should be noted that the length L of the resin particles refers to the length in the extrusion direction, and the average diameter D refers to the diameter of the cross section of the resin particles substantially orthogonal to the direction of the length L.

[0105] The average diameter D of the resin particles is preferably 0.5 mm to 1.5 mm. If the average diameter D is 0.5 mm or more, the retention of the foaming agent is improved, and the foaming property of the foaming particles is easily improved. If the average diameter D is 1.5 mm or less, the filling property of the foaming particles into the mold is improved, and it becomes easy to increase the thickness of the foaming molded body when manufacturing a plate-shaped foaming molded body.

[0106] (b) Foamable particles

[0107] The foamable particles are produced by impregnating the resin particles with a foaming agent. It should be noted that as a method for impregnating the resin particles with a foaming agent, a known method can be used. For example, the following method can be cited: resin particles, a dispersant, and water are supplied to an autoclave and stirred to disperse the resin particles in water to produce a dispersion liquid, and a foaming agent is pressed into the dispersion liquid to impregnate the resin particles with the foaming agent.

[0108] The dispersant is not particularly limited, and examples thereof include poorly water-soluble inorganic substances such as calcium phosphate, magnesium pyrophosphate, sodium pyrophosphate, magnesium oxide, and hydroxyapatite, and surfactants such as sodium dodecylbenzenesulfonate.

[0109] As the foaming agent, a general substance is used, for example, air; inert gases such as nitrogen and carbon dioxide (carbon dioxide gas); aliphatic hydrocarbons such as propane, butane, and pentane; halogenated hydrocarbons, preferably air, inert gases or aliphatic hydrocarbons. It should be noted that the foaming agent can be used alone or in combination of two or more.

[0110] The amount of the foaming agent impregnated in the resin particles is preferably 1 to 15 parts by mass relative to 100 parts by mass of the resin particles. If the content of the foaming agent is 1 part by mass or more, the foaming power does not decrease, and it is easy to foam well even at a high foaming ratio. If the content of the foaming agent is 15 parts by mass or less, the rupture of the bubble film is suppressed, and the plasticizing effect does not become excessively large, so the excessive reduction of the viscosity during foaming is suppressed, and the shrinkage is suppressed. The more preferred amount of the foaming agent is 2 to 12 parts by mass. If it is within this range, the foaming power can be fully improved, and foaming can be further well performed even at a high foaming ratio.

[0111] The impregnation temperature of the foaming agent into the resin particles is preferably 10°C to 120°C, more preferably 20°C to 110°C. If the impregnation temperature of the foaming agent is within this range, the time required for the foaming agent to be impregnated into the resin particles will not be prolonged, and the production efficiency will not be easily reduced. In addition, the resin particles are not easily welded to each other, and the occurrence of bonded particles is suppressed. A foaming aid (plasticizer) can also be used in combination with the foaming agent. Examples of the foaming aid (plasticizer) include diisobutyl adipate, toluene, cyclohexane, ethylbenzene, and the like.

[0112] (Foaming process)

[0113] (c) Foaming particles

[0114] In the foaming step, the foaming temperature, the heating medium, and the like are not particularly limited as long as the expandable particles can be expanded to obtain expandable particles.

[0115] It should be noted that before foaming, powdered metal soaps such as zinc stearate, calcium carbonate and aluminum hydroxide can be applied to the surface of the resin particles. By this coating, the bonding of the resin particles in the foaming process can be reduced. In addition, surface treatment agents such as antistatic agents and spreading agents can be applied. As antistatic agents, polyoxyethylene alkylphenol ethers and stearic acid monoglyceride can be cited. As spreading agents, polybutene, polyethylene glycol and silicone oil can be cited.

[0116] (4) Method for producing polyamide elastomer foamed molded product

[0117] The foaming molded body can be manufactured by filling foaming particles (suitably the foaming particles of the present invention) into a mold, heating and foaming them. For example, in a mold cavity formed by a pair of molds formed by combining the first mold and the second mold with a steam inlet, foaming particles (suitably the foaming particles of the present invention) containing a substrate resin are filled, and the mold and the foaming particles are heated with a heating medium to foam the foaming particles, thereby filling the pores between the foaming particles, and the foaming particles are welded and integrated to each other, thereby obtaining a foaming molded body.

[0118] When the foamed particles are filled, the density of the foamed molded product can be adjusted by adjusting the cracking rate between the first mold and the second mold, for example, so as to adjust the filling amount of the foamed particles. The cracking rate is, for example, 3% to 85%, preferably 5% to 85%, and more preferably 10% to 80%. When the cracking rate is within this range, the aesthetic appearance can be adjusted. It should be noted that the method for determining the cracking rate is as follows.

[0119] (Cracking rate)

[0120] The volume of the mold when the pair of molds are completely closed is a (cm 3 ) and the volume b (cm) of the mold where any cracking is performed 3 ), calculated according to the following formula.

[0121] Cracking rate (%) = ((ba) / a) × 100

[0122] During heat forming, preferably inorganic gas is impregnated in foamed particles to improve the foaming power (internal pressure imparting process) of foamed particles. By improving the foaming power, the weldability of foamed particles is improved during heat foaming, and the foamed molding has more excellent mechanical strength and long-term dimensional stability. The inorganic gas is, for example, an inert gas or air. The inert gas is, for example, carbon dioxide, nitrogen, helium, argon, etc. Preferred inorganic gas is air, nitrogen or carbon dioxide.

[0123] As a method for impregnating the foamed particles with an inorganic gas, for example, a method of impregnating the foamed particles with an inorganic gas by placing the foamed particles in an atmosphere of an inorganic gas having a pressure higher than normal pressure can be cited, preferably placing the foamed particles in an inorganic gas atmosphere of 0.01 MPa to 2.0 MPa for 1 minute to 24 hours, more preferably 5 minutes to 24 hours, and particularly preferably 20 minutes to 18 hours. In addition, the foamed particles are preferably impregnated with the inorganic gas before being filled into the mold, but can also be placed in an atmosphere of an inorganic gas together with the mold after the foamed particles are filled into the mold, thereby impregnating.

[0124] When the inorganic gas is impregnated into the foamed particles, the foamed particles can be heated and foamed directly in the mold, or the foamed particles can be heated and foamed before being filled into the mold, and then filled into the mold, heated and foamed after forming the foamed particles with a high expansion ratio. By using such foamed particles with a high expansion ratio, a foamed molded article with a high expansion ratio can be obtained.

[0125] Example

[0126] Hereinafter, one embodiment of the present invention will be described in further detail based on examples and the like, but the present invention is not limited to these embodiments.

[0127] Determination method

[0128] The determination described in the examples and the like was determined according to the following method.

[0129] [Biobased content]

[0130] Biobased content is determined according to ASTM D6866.

[0131] [Melting point of base resin]

[0132] The melting point of the base resin is determined according to ISO 11357.

[0133] [Shore D hardness of base resin]

[0134] For the Shore D hardness of the substrate resin, the instantaneous value was determined according to ISO 868.

[0135] [Density of base resin]

[0136] The density of the base resin is determined according to ISO 1183.

[0137] [Melt mass flow rate (MFR) of base resin]

[0138] After the test piece of the base resin (shape; pellet-like, size; 4.0 mm×3.0 mm×2.5 mm) was vacuum dried at 100°C for 3 hours, it was sealed and stored in a desiccator until the measurement. The test was performed according to the method b) of measuring the time for the piston to move a predetermined distance described in Method B of JIS K 7210:1999 "Plastics-Test Methods for Melt Mass Flow Rate (MFR) and Melt Volume Flow Rate (MVR) of Thermoplastics". That is, the "Melt Flow Indexer (Automatic) 120-SAS" manufactured by Yasuda Seiki Seisakusho Co., Ltd. was used, and the measurement conditions were set to test piece 3g to 8g, preheating for 300 seconds, load holding for 30 seconds, test temperature 230°C, test load 21.18N, and piston moving distance (interval): 25mm. The test number of the test piece was set to 3 times, and the average was taken as the value of melt mass flow rate (g / 10 minutes).

[0139] [Impuration Gas Amount of Expandable Particles (Blowing Agent Content)]

[0140] After impregnation with butane gas as a foaming agent, the mass W1 (g) of the foamable particles was immediately measured, and the particles were left to stand for 24 hours at a temperature of 23±2°C and a humidity of 50±5%. After standing, the mass W2 (g) of the foamable particles was measured, and the amount of impregnation gas was calculated according to the following formula.

[0141] The amount of impregnation gas in the foamable particles (mass %) = ((W1-W2) / W1) × 100

[0142] [Volume density of foamed particles]

[0143] Take the foamed beads before the internal pressure Wg is applied as the measurement sample, let the measurement sample fall naturally in the measuring cylinder, and then knock on the bottom of the measuring cylinder to make the apparent volume (V) of the sample cm 3 The weight and volume of the foamed particles were measured and the bulk density of the foamed particles was calculated based on the following formula.

[0144] Bulk density (g / cm 3 ) = weight of the sample to be measured (W) / volume of the sample to be measured (V)

[0145] [Inorganic gas (nitrogen) amount of foamed particles]

[0146] Weigh 70% of the volume of the sealed container with foamed particles, put them into the sealed container, seal the container, and pressurize it with an inorganic gas at a gauge pressure of 0.01MPa to 2MPa for an arbitrary time. After pressurization, purge the inorganic gas until the sealed container reaches atmospheric pressure, take out the foamed particles, and weigh them. The amount of inorganic gas is calculated according to the following formula.

[0147] Inorganic gas amount (mass %) = ((ba) / b) × 100

[0148] a: Weight of expanded particles before pressurization with inorganic gas (g)

[0149] b: Weight of expanded particles after pressurization with inorganic gas (g)

[0150] [Average particle size of foamed particles]

[0151] About 50 g of the expanded particles were classified for 5 minutes using a Ro-Tap type sieve vibrating machine (manufactured by SIEVE FACTORY IIDA Co., Ltd.) using JIS standard sieves with mesh sizes 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. The weight of the sample on the sieve is measured, and based on the cumulative weight distribution curve obtained from the result, the particle size (median particle size) at which the cumulative weight becomes 50% is defined as the average particle size.

[0152] [Density of foamed molded article]

[0153] Immediately after molding, the foamed molded body was dried at a temperature of 40°C for 12 hours, and then conditioned at a temperature of 23±2°C and a humidity of 50±5% for 72 hours. The mass a (g) of the foamed molded body after conditioning was measured to 2 decimal places, and the external dimensions were measured to 1 / 100 mm using a digital caliper (manufactured by Mitutoyo Corporation) to obtain the apparent volume b (cm 3 ). The density of the foamed molded body was calculated according to the following formula.

[0154] Density of foamed body (g / cm 3 )=a / b

[0155] [Resilience of Foam Molded Article]

[0156] Measured in accordance with JIS K 6400-3: 2011. Two test pieces of 50 mm × 50 mm × 20 mm thick cut from the same foam and left to stand for more than 72 hours in an environment of temperature 23 ± 2 ° C and humidity 50 ± 5% were overlapped and mounted on a rebound resilience tester (FR-2, manufactured by KOBUNSHI KEIKI CO., LTD.). A steel ball ( 16.3g) is freely dropped from a height of 500mm (a) toward the test piece, and the height (b) when the maximum rebound is reached is read. The rebound rate (%) is calculated according to the following formula. The same test piece is measured three times, and the average value is taken as the rebound rate.

[0157] Rebound rate (%) = ((b) / (a)) × 100

[0158] [Determination of complex viscosity]

[0159] Complex viscosity is measured according to JIS K 7244-1. Specifically, the resin to be the sample is pressed in a hot press to make a disc-shaped sample with a diameter of 25 mm and a thickness of 3 mm. Next, the plate of the dynamic viscoelasticity measuring device (PHYSICAMCR301 (manufactured by Anton Paar)) is heated to 220°C, the sample is set on the heated plate, and heated for 5 minutes under a nitrogen atmosphere to melt the sample. The gap between the plates is set to 2.0 mm, the exuded resin is removed, and the measurement is started 5 minutes after the measurement temperature is reached ±1°C. The measurement conditions are set to a frequency of 1 Hz, a strain of 1%, a normal force of ON, and a temperature of 220 to 50°C or 220 to 80°C (the cooling rate is 2°C / minute).

[0160] [Calculation of the first-order differential value of complex viscosity]

[0161] The complex viscosity values ​​at each temperature obtained by the measurement of the complex viscosity are subjected to first-order differential processing to obtain the minimum value and absolute value of the first-order differential value. Specifically, the difference in the complex viscosity values ​​at intervals of 5°C is divided by 5°C to obtain the first-order differential value. It should be noted that this processing is performed using EXCEL. From the first-order differential value of the complex viscosity as a function of temperature, the absolute value of the minimum value and the temperature at which the minimum value is shown are obtained.

[0162] [Asker C hardness of foamed molded article]

[0163] After conditioning a smooth surface test piece with a thickness of 10 mm or more under an environment of temperature 23±2°C and humidity 50±5% for more than 72 hours, the Asker C hardness is measured using a hardness tester "Asker Rubber / Plastic Hardness Tester Type C" manufactured by KOBUNSHI KEIKI CO., LTD. The pressing surface is brought into close contact with the smooth measuring surface of the test piece in such a way that the pressing needle is perpendicular to the smooth measuring surface of the test piece, and the scale is immediately read. Avoid the welded surfaces of the foam particles, measure 5 locations of the sample, and take their average value as the Asker C hardness.

[0164] Amide elastomer resin

[0165] The details of Pebax manufactured by Arkema used as the base resin in the Examples and Comparative Examples are as follows.

[0166] Pebax Rnew35R53 SP01; biobased content 28-32%, melting point 146°C, Shore D hardness 32, density 1.02g / cm 3

[0167] Pebax Rnew40R53 SP01; biobased content 44-48%, melting point 148°C, Shore D hardness 38, density 1.03g / cm 3

[0168] Pebax 4533SA01; biobased content 0%, melting point 148°C, Shore D hardness 42, density 1.01g / cm 3

[0169] Pebax 3533SA01; biobased content 0%, melting point 144°C, Shore D hardness 25, density 1.00g / cm 3

[0170] Pebax 4033SA01; biobased content 0%, melting point 160°C, Shore D hardness 37, density 1.00g / cm 3

[0171] Pebax Rnew55R53 SP01; biobased content 62-66%, melting point 167°C, Shore D hardness 48, density 1.03g / cm 3

[0172] Pebax 5533SA01; biobased content 0%, melting point 159°C, Shore D hardness 50, density 1.01g / cm 3

[0173] It should be noted that Pebax Rnew35R53 SP01, 40R53 SP01 and 55R53 SP01 are polyamide elastomers having a polyamide 11 block derived from castor oil as a hard segment and a polyether block as a soft segment, and Pebax4533SA01, 3533SA01, 4033SA01 and 5533SA01 are polyamide elastomers having a polyamide 12 block derived from petroleum as a hard segment and a polyether block as a soft segment.

[0174] Example 1

[0175] <Preparation of Expandable Particles>

[0176] In an autoclave with an internal volume of 5 L, 1.0 kg (100 parts by mass) of the amide elastomer resin particles shown in Table 1 were placed and sealed. Carbon dioxide as a blowing agent was pressed into the autoclave so that the pressure in the autoclave became 4.0 MPa, and the autoclave was left to stand at 20° C. for 72 hours. Thereafter, the autoclave was depressurized to obtain expandable particles. The amount of gas impregnated with the expanding agent in the expandable particles was 8.5% by mass.

[0177] <Preparation of foamed particles>

[0178] 1.0 kg (100 parts by mass) of the obtained foamable particles were coated with 0.5 parts by mass of an anti-binding agent (polyoxyethylene-polyoxypropylene glycol: "Epan 740", manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), and then placed in a cylindrical pre-foaming machine with a stirrer having an internal volume of 50 L, and heated with 0.015 MPa of steam while stirring to foam (pre-foam) the particles to obtain foamable particles. The bulk density was 0.13 g / cm 3 .

[0179] <Manufacturing of foamed molded article>

[0180] The expanded beads were placed in a sealed container (autoclave), nitrogen gas was pressurized into the sealed container at 0.5 MPa, and the container was left to stand at room temperature for 18 hours to allow the nitrogen gas to permeate into the expanded beads (internal pressure application).

[0181] The foamed particles taken out from the sealed container are immediately filled into a molding cavity (150 mm×150 mm×20 mm thick) of a molding device having a pair of molds formed by a concave mold and a convex mold. After the filling is completed, the molds are closed and heated with water vapor to obtain a foamed molded body.

[0182] Embodiments 2 to 7

[0183] <Preparation of Expandable Particles>

[0184] 100 parts by weight of amide elastomer resins of the mass ratios shown in Tables 1 and 2 were supplied to a single screw extruder, melt kneaded at 160°C, and then further melt kneaded while heating to 220°C. After cooling the molten base resin, the resin was extruded from each nozzle of a multi-nozzle die (having four nozzles with a diameter of 1 mm) installed at the front end of the single screw extruder, and cut in water at 20°C to 50°C. The obtained resin pellets were cylindrical, with an average length of 1.5 mm and an average diameter of 1.5 mm.

[0185] In an autoclave with a stirring blade having an internal volume of 5 L, 1.0 kg (100 parts by mass) of the obtained resin particles, 3.0 kg of distilled water, and an aqueous solution of sodium dodecylbenzenesulfonate (25% aqueous solution) were placed and sealed. 18 parts by mass of butane (n-butane: isobutane = 7:3 (volume ratio)) as a foaming agent was pressed in while stirring. Next, the temperature in the autoclave was raised to 70°C, heated for 2 hours, and cooled to 25°C. After cooling, the autoclave was depressurized, the surfactant was immediately washed with distilled water, and dehydrated, thereby obtaining foamable particles.

[0186] Using the obtained expandable beads, expandable beads and a foamed molded article were produced in the same manner as in Example 1.

[0187] Comparative Example 1

[0188] 100 parts by mass of the amide elastomer resin shown in Table 3 was supplied to a twin-screw extruder, melt-kneaded at 160°C, and then further melt-kneaded while heating to 220°C. After cooling the molten base resin, the resin was extruded from each nozzle of a multi-nozzle die (having four nozzles with a diameter of 1 mm) installed at the front end of the twin-screw extruder, and cut in water at 20°C to 50°C. The obtained resin pellets were cylindrical, with an average length of 1.5 mm and an average diameter of 1.5 mm.

[0189] Using the obtained resin particles, expandable particles, expandable particles, and a foamed molded article were produced in the same manner as in Examples 2 to 7.

[0190] Comparative Example 2

[0191] Except that the base resin was replaced with the amide elastomer resin and the mass ratio described in Table 3, the same procedure as in Example 1 was carried out to obtain expandable beads, expandable beads and a foamed molded article.

[0192] Comparative Examples 3 to 4

[0193] Except that the base resin was replaced with the amide elastomer resin and the mass ratio described in Table 3, the same procedures as in Examples 2 to 7 were carried out to obtain expandable beads, expandable beads, and a foamed molded article.

[0194] The complex viscosity behavior of the base resins used in Example 1 and Comparative Examples 1 and 2 is shown in Figure 1 . Figure 1 It is shown that the base resin with low Shore D hardness used in Example 1 has a lower temperature at which the complex viscosity starts to decrease than the base resins used in Comparative Examples 1 and 2. In addition, the base resins used in Examples have a gentle slope at which the complex viscosity decreases.

[0195] In order to quantitatively evaluate the viscosity reduction, the first-order differential value of the complex viscosity diagram was calculated, and the relationship between the differential value and temperature is shown in Figure 2 . Figure 1 The base resin used in the comparative example in which the slope of the decrease in the complex viscosity is steep has a small minimum value (a large absolute value of the minimum value).

[0196] In order to visually recognize the relationship between the minimum value and the temperature, a graph was prepared in which the vertical axis is the absolute value of the minimum value and the horizontal axis is the temperature showing the minimum value ( Figure 3 The base resin used in the example has a smaller absolute value of the minimum value than the base resin used in the comparative example (in other words, Figure 1 The slope of the decrease of the complex viscosity in the viscosity is small), and the temperature showing the minimum value is low. It is thus confirmed that the amide elastomer resin having a Shore D hardness of 40 or less, an absolute value of the minimum value of 1.0E+05 or less, and a temperature showing the minimum value of 134°C or less provides lightness, softness, and high resilience to the foamed molded article.

[0197] The properties of the base resin, the foamed particles, and the foamed molded article are shown in Tables 1 to 3.

[0198] [Table 1]

[0199]

[0200] [Table 2]

[0201]

[0202] [Table 3]

[0203]

Claims

1. A foamed particle, which is an amide elastomer foamed particle containing an amide elastomer resin as a base resin, The foamed particles contain 50 to 100% by mass of the amide elastomer resin, The amide elastomer resin has a Shore D hardness of 40 or less, The amide elastomer resin is as follows: the complex viscosity value obtained in the dynamic viscoelasticity measurement under temperature dispersion conditions is subjected to first-order differential processing, and the minimum value is determined from the obtained differential value. The absolute value of the minimum value is less than 1.0E+05, and the temperature at the minimum value is less than 134°C.

2. The foamed particles according to claim 1, wherein The amide-based elastomer resin has a polyamide block as a hard segment and a polyether block as a soft segment.

3. The foamed particles according to claim 1 or 2, wherein The amide elastomer resin has a Shore D hardness of 38 or less.

4. The foamed beads according to any one of claims 1 to 3, wherein The absolute value of the minimum value is less than 8.0E+04.

5. The foamed beads according to any one of claims 1 to 4, wherein The temperature at the minimum value is 133° C. or less.

6. A foamed molded product, which is an amide elastomer foamed molded product using an amide elastomer resin as a base resin, wherein the foamed molded product contains 50 to 100% by mass of the amide elastomer resin. The amide elastomer resin has a Shore D hardness of 40 or less, The amide elastomer resin is as follows: the complex viscosity value obtained in the dynamic viscoelasticity measurement under temperature dispersion conditions is subjected to first-order differential processing, and the minimum value is determined from the obtained differential value. The absolute value of the minimum value is less than 1.0E+05, and the temperature at the minimum value is less than 134°C.

7. The foamed molded article according to claim 6, wherein The amide-based elastomer resin has a polyamide block as a hard segment and a polyether block as a soft segment.

8. The foamed molded article according to claim 6 or 7, wherein The amide elastomer resin has a Shore D hardness of 38 or less.

9. The foamed molded product according to any one of claims 6 to 8, wherein The absolute value of the minimum value is less than 8.0E+04.

10. The foamed molded product according to any one of claims 6 to 9, wherein The temperature at the minimum value is 133° C. or less. 11 . The foamed molded product according to claim 6 , which has a rebound resilience of 70% or more.

12. The foamed molded product according to any one of claims 6 to 11, which has a density of 0.20 g / cm 3 the following. 13 . The foamed molded product according to claim 6 , which has an Asker C hardness of 38 or less.

14. A method for producing a foamed molded article, wherein: The expanded beads according to any one of claims 1 to 5 are filled into a mold, heated, and expanded.

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