JP5992723B2 - Thermoplastic elastomer composition for extrusion foam molding and extruded foam molding comprising the resin composition - Google Patents

Description

  The present invention relates to a thermoplastic elastomer composition for extrusion foam molding and an extrusion foam molded article using the same.

  Foam is widely used in members that require shock absorbing performance and cushioning properties such as cushioning materials such as electronic devices and furniture, automobile interior materials, food packaging materials, and the like. Among them, a thermoplastic elastomer foam is suitably used for applications that require cushioning and flexibility. In particular, extrusion foam molding has the merit that the cost can be kept low by continuously producing it, and is useful for the production of a molded body having a simple shape.

  For example, Patent Document 1 discloses that a composition comprising a polyolefin-based elastomer and polypropylene is extruded and foamed. According to this method, it is possible to obtain a soft foam, but it is difficult to obtain a foam having a uniform cell structure and a smooth surface due to poor dispersibility of polypropylene. Patent Document 2 discloses extrusion molding of a mixture of a partially crosslinked thermoplastic elastomer and a long-chain branched polypropylene. According to this method, a product having a high expansion ratio exceeding 2 times can be obtained. However, when the MFR of the long-chain branched polypropylene, which is a minor component, is lower than that of the thermoplastic elastomer, the dispersion is insufficient and The uniformity may be lost or the thickness of the foam may be non-uniform, especially when 20% or more of the long-chain branched polypropylene is added. Patent Document 3 discloses an injection foam molding composition comprising a thermoplastic elastomer and a high melt tension polypropylene. Although extrusion foaming is not disclosed here, it is possible to obtain an extruded foam having good foamability by directly applying these compositions to extrusion foaming. However, when the MFR of the high melt tension PP is lower than that of the thermoplastic elastomer, the dispersion may be insufficient and the foam uniformity may be lost or the thickness of the foam may be uneven.

JP 2004-250529 A Japanese Patent Laid-Open No. 9-296063 JP2011-102028

  An object of the present invention is to provide a thermoplastic elastomer composition for extrusion foam molding which can provide an extrusion foam molded article having a high foaming ratio, no voids, and excellent softness and appearance smoothness.

  The present inventors improve the dispersibility during extrusion by mixing a specific thermoplastic resin with a specific thermoplastic elastomer, have good appearance without voids, and have a soft feeling peculiar to elastomer foams. The inventors found that a molded body can be obtained and have completed the present invention.

  That is, this invention consists of the following structures.

1). A thermoplastic elastomer (A) having a melt flow rate (MFR (A), 230 ° C., 2.16 kg) of 20 g / 10 min or less and a type A hardness of 40 to 80 wt%, and the following (a) A thermoplastic elastomer composition for extrusion foam molding comprising 3 to 50% by weight of a modified polypropylene resin (B) satisfying the characteristics of (d).
(A) Melt flow rate (MFR (B), 230 ° C., 2.16 kg) is 3 g / 10 min or more, and MFR (B)> MFR (A)
(B) Melt tension at 200 ° C. is 0.5 cN or more (c) Loss tangent tan δ, which is a ratio of storage elastic modulus and loss elastic modulus at an angular frequency of 1 rad / s in dynamic viscoelasticity measurement at 200 ° C. I) satisfying the following i) and ii) i) When MFR is 3 or more and less than 30, tanδ is 2.0 or less ii) When MFR is 30 or more, tanδ is 4.0 or less The thermoplastic elastomer composition for extrusion foam molding according to 1), wherein the particle size of (B) is 4 mm or less.

  3). The thermoplastic elastomer composition for extrusion foam molding according to 1) or 2), wherein MFR (B) / MFR (A)> 3.

  4). The thermoplastic elastomer composition for extrusion foam molding according to any one of 1) to 3), wherein MFR (A) is 0.1 to 10 and MFR (B) is 4.5 or more.

  5). The modified polypropylene resin is obtained by melt-mixing a linear polypropylene resin, a radical polymerization initiator and a conjugated diene compound, for extrusion foam molding according to any one of 1) to 4) Thermoplastic elastomer composition.

  6). An extrusion foam molded article obtained by extrusion foaming the elastomer composition for extrusion foam molding according to any one of 1) to 5).

  Since the thermoplastic elastomer composition for extrusion foam molding of the present invention contains a specific polypropylene-based resin in a specific thermoplastic elastomer, the thermoplastic elastomer composition has excellent foamability and can be highly foamed. Therefore, it is possible to obtain an extruded foam molded body having a soft feeling and having a high expansion ratio.

  That is, the thermoplastic elastomer composition for extrusion foam molding of the present invention can provide an extruded foam molded article free from voids, having a high foaming ratio, having a soft feeling, and having a good appearance.

  The thermoplastic elastomer composition for injection foam molding of the present invention comprises a specific thermoplastic elastomer and a polypropylene resin in a specific ratio.

  The thermoplastic elastomer (A) used in the present invention has a melt flow rate (MFR (A)) of 20 g / 10 min or less, preferably 0.1 or more and 10 g / 10 min or less. When the melt flow rate of the thermoplastic elastomer is within the above range, an extruded foam molded article having a desired hardness without voids can be obtained.

  Here, the melt flow rate (hereinafter sometimes abbreviated as “MFR”) conforms to the provisions of Method A described in JIS K7210 (1999), and uses a melt indexer S-01 (manufactured by Toyo Seiki Seisakusho). It is a value converted from the amount of resin extruded from a die at a constant time under a load of 2.16 kg at 230 ° C. to the amount extruded in 10 minutes. The predetermined time is 240 seconds when the melt flow rate is 0.5 g / 10 minutes or less, 120 seconds when the melt flow rate is more than 0.5 g / 10 minutes and 1.0 g / 10 minutes or less, and 1.0 g / If it exceeds 10 minutes and is 3.5 g / 10 minutes or less, it is 60 seconds. If it is more than 3.5 g / 10 minutes and is 10 g / 10 minutes or less, it is 30 seconds. If it is more than 10 g / 10 minutes and 25 g / 10 minutes or less Is 10 seconds, 5 seconds when it exceeds 25 g / 10 minutes and 100 g / 10 minutes or less, and 3 seconds when it exceeds 100 g / 10 minutes. Three pieces cut out at the predetermined time are collected and the average value is calculated. If three pieces cannot be collected in one measurement, the measurement is continued until three pieces can be collected. If the melt flow rate measured in a certain number of seconds is not in the corresponding range, the measurement is performed again in the number of seconds corresponding to the melt flow rate.

  The MFR of the thermoplastic elastomer (A) is MFR (A), and the MFR of the modified polypropylene resin (B) described later is MFR (B).

The thermoplastic elastomer (A) used in the present invention has a type A hardness of 40 to 80, preferably 45 to 75. When the type A hardness is within the above range, it is easy to obtain a product having a good balance such as cushioning property and heat resistance of the obtained extruded foamed product.
Here, the type A hardness means a value measured by a type A durometer hardness test in an environment of 23 ° C. according to JIS K6253.

  Examples of the thermoplastic elastomer (A) used in the present invention include an ethylene-α-olefin copolymer, a propylene-α-olefin copolymer, an ethylene-propylene-diene copolymer, an ethylene-vinyl acetate copolymer, and a polybutene. Olefin-based elastomers such as chlorinated polyethylene; styrene-isobutylene-styrene copolymers, styrene-isobutylene copolymers, styrene-butadiene-styrene copolymers, styrene-isoprene-styrene copolymers, and hydrogenated products thereof Styrenic elastomers such as; polyester-based elastomers; polyamide-based elastomers; polyurethane-based elastomers, and mixtures of these and polyolefin-based resins such as polypropylene and polyethylene by means of polymerization, blending, melt-kneading, etc. Etc.

  These thermoplastic elastomers are not particularly limited as long as they have the above-mentioned properties, and can be used alone or in combination of two or more, but the modified polypropylene resin (B) described later can be used. From the viewpoint of easy dispersibility and desired hardness and relatively low cost, an ethylene-α-olefin copolymer or a mixture of these with a polyolefin resin is preferred.

  Furthermore, from the viewpoint of easy dispersibility in polypropylene and desired hardness, the density of the thermoplastic elastomer (A) is preferably 0.85 g / cm 3 or more and 0.880 g / cm 3 or less, and 0.855 g / cm 3 or more and 0 or more. 875 g / cm 3 or less is more preferable.

  The modified polypropylene resin (B) used in the present invention has (a) a melt flow rate (MFR (B)) of 3 g / 10 min or more and MFR (B)> MFR (A), (b) at 200 ° C. The melt tension is 0.5 cN or higher, and (c) the loss tangent tan δ, which is the ratio of the storage elastic modulus to the loss elastic modulus at an angular frequency of 1 rad / s in dynamic viscoelasticity measurement at 200 ° C., is 5 or higher. When it is less than 30, tan δ needs to be 2.0 or less, and when MFR is 30 or more, tan δ needs to be 4.0 or less. By satisfying this condition, the olefin-based elastomer (A) having poor foamability can be obtained. It becomes possible to impart foamability efficiently.

    If the melt flow rate (MFR (B)) of the modified polypropylene resin (B) is in the above range, it is preferable because the dispersibility of the composition is improved or a foam having a good appearance without voids is obtained. The MFR (B) is preferably 4.5 g / 10 min or more, and more preferably MFR (B) / MFR (A)> 3.

  There is no particular restriction on the upper limit, but if it is too high, there may be problems with stability such as unstable discharge or drooping of the extrudate, and the combination with the added amount and thermoplastic elastomer (A) However, it is preferably 250 g / 10 min or less, more preferably 100 g / 10 min or less.

  Here, the melt flow rate of the modified polypropylene resin (B) was measured in the same manner as the olefin elastomer (A).

  When the melt tension of the modified polypropylene resin (B) is in the above range, defoaming immediately after the die during extrusion foam molding tends to be suppressed, and the rough surface of the foam tends to be improved. It is preferably 8 cN or more, more preferably 1.0 cN or more. The upper limit of the melt tension is not particularly limited, but is preferably 15 cN or less. When it exceeds 15 cN, the mixability with the thermoplastic elastomer (A) may be deteriorated, and the void generation state and surface smoothness may be deteriorated, more preferably 10 cN or less.

  Here, the melt tension is equipped with an attachment for measuring melt tension, using a capillograph (manufactured by Toyo Seiki Seisakusho) having a 10 mmφ cylinder with an orifice having an inner diameter of 1 mmφ and a length of 10 mm at the tip. The strand discharged from the die when it is lowered at 10 ° C / min. At a temperature of 10 ° C. is pulled at a speed of 1 m / min on a pulley with a load cell 350 mm below, and after stabilization, the take-up speed is 200 m / min for 4 minutes. The load applied to the pulley with a load cell when the strand breaks is increased at a rate reaching the speed. If the strand does not break, the melt tension is the load at which the load applied to the pulley with the load cell does not increase even if the take-up speed is increased.

  When the tan δ of the modified polypropylene resin (B) is in the above range, it becomes possible to impart foamability to the olefin elastomer (A) having poor foamability. When the MFR is 5 or more and less than 30, tan δ Is 1.8 or less, and when MFR is 30 or more, tan δ is preferably 3.5 or less.

  As modified polypropylene resin (B) resin which has the above characteristics, what has a branched structure or a high molecular weight component is mentioned, for example. As a method for producing such a modified polypropylene resin (B), for example, radiation is applied to a linear polypropylene resin, or a linear polypropylene resin, a conjugated diene compound, and a radical polymerization initiator are melt mixed. The method is mentioned. In the present invention, those having a branched structure are particularly preferred. As a method for producing the same, a modified polypropylene resin obtained by melt-mixing a linear polypropylene resin, a conjugated diene compound and a radical polymerization initiator is expensive. It is preferable from the point that it can be manufactured inexpensively by not requiring it.

The linear polypropylene resin used in the production of the modified polypropylene resin (B) of the present invention is a polypropylene resin having a linear molecular structure, specifically, a propylene homopolymer. And a block copolymer and a random copolymer, which are crystalline polymers. As a copolymer of propylene, a copolymer containing propylene in an amount of 75% by weight or more is preferable in that the crystallinity, rigidity, chemical resistance, etc., which are characteristics of the polypropylene resin, are maintained. The copolymerizable α-olefin is ethylene, 1-butene, isobutene, 1-pentene, 3-methyl-1-butene, 1-hexene, 4-methyl-1-pentene, 3,4-dimethyl-1-butene. , 1-heptene, 3-methyl-1-hexene, 1-octene, 1-decene and the like, such as α-olefins having 2 or 4 to 12 carbon atoms, cyclopentene, norbornene, tetracyclo [6,2,11,8,13, 6] Cyclic olefins such as -4-dodecene, 5-methylene-2-norbornene, 5-ethylidene-2-norbornene, 1,4-hexadiene, methyl-1,4-hexadiene, 7-methyl-1,6-octadiene Such as dienes, vinyl chloride, vinylidene chloride, acrylonitrile, vinyl acetate, acrylic acid, methacrylic acid, maleic acid, ethyl acrylate, Examples thereof include vinyl monomers such as butyl acrylate, methyl methacrylate, maleic anhydride, styrene, methyl styrene, vinyl toluene, and divinyl benzene. These may be used alone or in combination of two or more.
Among these, ethylene and 1-butene are preferable from the viewpoints of improving cold brittleness resistance and low cost.

  Examples of the conjugated diene compound include butadiene, isoprene, 1,3-heptadiene, 2,3-dimethylbutadiene, 2,5-dimethyl-2,4-hexadiene, and the like. These may be used alone or in combination of two or more.

  Among these, butadiene and isoprene are particularly preferable because they are inexpensive and easy to handle and the reaction easily proceeds uniformly.

  The addition amount of the conjugated diene compound is preferably 0.01 parts by weight or more and 20 parts by weight or less, and more preferably 0.05 parts by weight or more and 5 parts by weight or less with respect to 100 parts by weight of the linear polypropylene resin. If the addition amount of the conjugated diene compound is less than 0.01 parts by weight, the effect of the modification may be difficult to obtain, and if the addition amount exceeds 20 parts by weight, the effect is saturated and may not be economical. is there.

  Monomers copolymerizable with the conjugated diene compounds, such as vinyl chloride, vinylidene chloride, acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, vinyl acetate, acrylic acid, methacrylic acid, maleic acid, maleic anhydride, acrylic acid Metal salts, metal methacrylate salts, methyl acrylate, ethyl acrylate, butyl acrylate, acrylic acid esters such as 2-ethylhexyl acrylate, stearyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, methacrylic acid 2 -You may use together methacrylic acid esters, such as ethylhexyl and stearyl methacrylate.

  The radical polymerization initiator generally includes peroxides, azo compounds, and the like, but those having a capability of extracting hydrogen from a polypropylene resin or the conjugated diene compound are preferable. Generally, ketone peroxides, peroxyketals, hydroperoxides are used. Organic peroxides such as oxides, dialkyl peroxides, diacyl peroxides, peroxydicarbonates, and peroxyesters are listed. Of these, those having particularly high hydrogen abstraction ability are preferred, such as 1,1-bis (t-butylperoxy) 3,3,5-trimethylcyclohexane, 1,1-bis (t-butylperoxy) cyclohexane, Peroxyketals such as n-butyl 4,4-bis (t-butylperoxy) valerate, 2,2-bis (t-butylperoxy) butane, dicumyl peroxide, 2,5-dimethyl-2,5 -Di (t-butylperoxy) hexane, α, α'-bis (t-butylperoxy-m-isopropyl) benzene, t-butylcumyl peroxide, di-t-butylperoxide, 2,5-dimethyl Diacyl peroxides such as dialkyl peroxides such as -2,5-di (t-butylperoxy) -3-hexyne and benzoyl peroxides Xide, t-butyl peroxyoctate, t-butyl peroxyisobutyrate, t-butyl peroxylaurate, t-butyl peroxy 3,5,5-trimethylhexanoate, t-butyl peroxyisopropyl carbonate Peroxyesters such as 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, t-butylperoxyacetate, t-butylperoxybenzoate, and di-t-butylperoxyisophthalate. It is done. These may be used alone or in combination of two or more.

  The addition amount of the radical polymerization initiator is preferably from 0.01 to 10 parts by weight, more preferably from 0.05 to 4 parts by weight, based on 100 parts by weight of the linear polypropylene resin. If the addition amount of the radical polymerization initiator is less than 0.01 parts by weight, the effect of the modification may be difficult to obtain. If the addition amount exceeds 10 parts by weight, the effect of the modification is saturated and it is not economical. There is a case.

  The equipment for reacting the linear polypropylene resin, the conjugated diene compound, and the radical polymerization initiator includes a kneading machine such as a roll, a kneader, a Banbury mixer, a Brabender, a single screw extruder, a twin screw extruder, and a biaxial surface. An updater, a horizontal stirrer such as a biaxial multi-disk device, a vertical stirrer such as a double helical ribbon stirrer, and the like. Among these, a kneader is preferably used, and an extruder is particularly preferable from the viewpoint of productivity.

  There is no particular limitation on the order and method of mixing and kneading (stirring) the linear polypropylene resin, the conjugated diene compound, and the radical polymerization initiator. The linear polypropylene resin, the conjugated diene compound, and the radical polymerization initiator may be mixed and then melt-kneaded (stirred), or after the polypropylene resin is melt-kneaded (stirred), the conjugated diene compound or radical initiator may be mixed simultaneously. Alternatively, they may be mixed separately, collectively or divided. The temperature of the kneading (stirring) machine is preferably 130 ° C. or more and 300 ° C. or less from the viewpoint that the linear polypropylene resin melts and does not thermally decompose. The time is generally preferably 1 to 60 minutes.

  There is no restriction | limiting in the shape and magnitude | size of the modified polypropylene resin (B) obtained in this way, A pellet form may be sufficient.

  The method for mixing the thermoplastic elastomer (A) and the modified polypropylene resin (B) is not particularly limited, and can be performed by a known method. Examples of the mixing method include methods such as dry blending both pellets using a blender, a mixer, etc., melt mixing, and dissolving and mixing in a solvent. In the present invention, the method of dry blending and then subjecting to extrusion foaming is preferable because the heat history is small and the decrease in the melt tension of the modified polypropylene resin (B) is small.

  The thermoplastic elastomer composition for extrusion foam molding of the present invention comprises 50% by weight to 97% by weight of the thermoplastic elastomer (A) and 3% by weight to 50% by weight of the modified polypropylene resin (B). Preferably, the thermoplastic elastomer composition (A) comprises 60 wt% or more and 95 wt% or less, and the modified polypropylene resin (B) comprises 5 wt% or more and 40 wt% or less [(A) and (B). Is 100% by weight].

  When the blending ratio of the thermoplastic elastomer (A) and the modified polypropylene resin (B) is within the above range, an extruded foam having a soft feeling at a high expansion ratio can be obtained.

  The foaming agent used in the present invention is not particularly limited as long as it can be usually used for injection foam molding, such as a chemical foaming agent and a physical foaming agent. A chemical foaming agent decomposes | disassembles and generate | occur | produces gas, such as a carbon dioxide gas, It can supply to an injection molding machine, after previously mixing with the said resin. Examples of the chemical foaming agent include inorganic chemical foaming agents such as sodium bicarbonate and ammonium carbonate, and organic chemical foaming agents such as azodicarbonamide and N, N′-dinitrosopentamethylenetetramine. These may be used alone or in combination of two or more.

  A physical foaming agent is injected into a molten resin in a cylinder of a molding machine as a gaseous or supercritical fluid, dispersed or dissolved, and functions as a foaming agent by being released from pressure after being injected into a mold. Is. Physical foaming agents include aliphatic hydrocarbons such as propane and butane, alicyclic hydrocarbons such as cyclobutane and cyclopentane, halogenated hydrocarbons such as chlorodifluoromethane and dichloromethane, nitrogen, carbon dioxide, air, etc. Inorganic gas. These may be used alone or in combination of two or more.

  Among these foaming agents, an ordinary extruder can be used safely, and uniform fine bubbles are easily obtained. As a chemical foaming agent, an inorganic chemical foaming agent, and as a physical foaming agent, nitrogen, carbonic acid are used. Inorganic gases such as gas and air are preferred.

  These foaming agents include, for example, foaming aids such as organic acids such as citric acid and inorganic fine particles such as talc and lithium carbonate, in order to stably and uniformly make the bubbles of the extruded foam. A nucleating agent such as may be added. Usually, the inorganic chemical foaming agent is used by preparing a masterbatch of a polyolefin resin having a concentration of 10 to 50% by weight from the viewpoints of handleability, storage stability, and dispersibility in a thermoplastic elastomer composition. Is preferred.

  What is necessary is just to set the usage-amount of the said foaming agent suitably with the foaming magnification of the extrusion foam obtained, the kind of foaming agent, and the resin temperature at the time of extrusion. For example, in the case of an inorganic chemical foaming agent, it is usually preferably 0.5 parts by weight or more and 20 parts by weight or less, more preferably 1 part by weight or more with respect to 100 parts by weight of the thermoplastic elastomer composition for extrusion foam molding. It is used in the range of 15 parts by weight or less. By using the inorganic chemical foaming agent in the above range, it is easy to economically obtain an extruded foam having a foaming ratio of 2 times or more and uniform fine cells. In the case of a physical foaming agent, the extrusion is performed in the range of 0.05 to 10 parts by weight, preferably 0.1 to 5 parts by weight with respect to 100 parts by weight of the polypropylene resin of the present invention. Used to supply the machine.

  As for the method of adding the foaming agent, a thermoplastic foaming composition for extrusion foam molding that has been dry blended with a chemical foaming agent or an impregnated physical foaming agent may be supplied to an injection molding machine in advance. After the thermoplastic elastomer composition for extrusion foam molding other than the foaming agent is supplied to the extruder, the foaming agent may be added from the middle of the extruder cylinder.

  In the present invention, if necessary, fluidity improvers such as lubricants, polyolefin waxes, antioxidants, metal deactivators, phosphorus-based processing stabilizers, ultraviolet absorbers, as long as the effects of the present invention are not impaired. Stabilizer, light stabilizer, fluorescent brightener, metal soap, antacid adsorbent stabilizer, cross-linking agent, chain transfer agent, nucleating agent, plasticizer, filler, reinforcing material, pigment, dye, flame retardant, electrification You may use together additives, such as an inhibitor. Of course, these additives used as necessary are used within a range not impairing the effects of the present invention, but with respect to 100 parts by weight of the thermoplastic elastomer composition for extrusion foam molding of the present invention, Preferably, it is used in 0.01 parts by weight or more and 40 parts by weight or less.

  The thermoplastic elastomer composition for extrusion foam molding of the present invention obtained as described above is extruded and foamed to obtain an extruded foam.

  In the present invention, a foam is obtained by extruding a thermoplastic elastomer composition for extrusion foam molding into a low pressure region from a die attached to the tip of the extruder. Here, the low pressure region refers to the pressure region outside the extruder with respect to the die pressure in the extruder.

  As an apparatus used for obtaining a foam, for example, a single-screw, twin-screw or multi-screw extruder, or a tandem extruder in which one or two types selected from them are connected in series may be used. it can. In addition, an onrator used for the purpose of uniformly kneading and cooling the foamable composition, and an accumulator used for the purpose of adjusting and cooling the speed at which the foamable composition is extruded from the die are also part of the apparatus for extrusion foaming. Preferably used.

  Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

  In the examples and comparative examples, the test methods and criteria used in various evaluation methods are as follows.

(1) Melt flow rate (MFR):
MFR conforms to the provisions of Method A described in JIS K 7210 (1999), and uses a melt indexer S-01 (manufactured by Toyo Seiki Seisakusho) at 230 ° C. under a constant load (2.16 kg) for a certain period of time from the die. It was set as the value converted into the amount extruded for 10 minutes from the amount of resin extruded to 10 minutes.

  The predetermined time is 240 seconds when the melt flow rate is 0.5 g / 10 minutes or less, 120 seconds when the melt flow rate is more than 0.5 g / 10 minutes and 1.0 g / 10 minutes or less, and 1.0 g / If it exceeds 10 minutes and is 3.5 g / 10 minutes or less, it is 60 seconds. If it is more than 3.5 g / 10 minutes and is 10 g / 10 minutes or less, it is 30 seconds. If it is more than 10 g / 10 minutes and 25 g / 10 minutes or less Is 10 seconds, 5 seconds when it exceeds 25 g / 10 minutes and 100 g / 10 minutes or less, and 3 seconds when it exceeds 100 g / 10 minutes.

  Three pieces cut out at the predetermined time are collected and the average value is calculated. If three pieces cannot be collected in one measurement, the measurement is continued until three pieces can be collected. If the melt flow rate measured in a certain number of seconds is not in the corresponding range, the measurement is performed again in the number of seconds corresponding to the melt flow rate.

(2) Melt tension:
It is equipped with an attachment for melt tension measurement, using a capilograph (manufactured by Toyo Seiki Seisakusho) with a φ10 mm cylinder fitted with an orifice of φ1 mm and a length of 10 mm at the tip, at a piston descending speed of 10 mm / min. When lowered, the strand discharged from the die is applied to a pulley with a load cell 350 mm below and taken up at a speed of 1 m / min. After stabilization, the take-up speed is increased at a rate of reaching 200 m / min in 4 minutes. The load applied to the pulley with a load cell when ruptured was defined as melt tension. When the strand did not break, the load at the point where the load applied to the pulley with the load cell did not increase even when the take-up speed was increased was defined as the melt tension.

(3) Loss tangent tan δ
A polypropylene resin is hot-pressed at 190 ° C for 5 minutes using a spacer with a thickness of 1.5 mm to produce a 1.5 mm-thick press plate, and punched out with a 25 mmφ punch to obtain a test piece. It was. As a measuring device, a viscoelasticity measuring device ARES made by TA Instruments was used, and a parallel plate type jig of 25 mmφ was attached. A thermostatic chamber was installed to surround the jig, kept at 200 ° C., and after the jig was preheated, the thermostat was opened, a test piece with 25 mmφ was inserted between the parallel plates, the thermostat was closed and preheated for 5 minutes. Later, the parallel plate spacing was compressed to 1 mm. After compression, the thermostat was opened again, the resin protruding from the parallel plate was scraped off with a brass spatula, the thermostat was closed and the temperature was kept again for 5 minutes, and then dynamic viscoelasticity measurement was started.

  The measurement was performed in the range of angular frequency from 0.1 rad / s to 100 rad / s, and storage elastic modulus and loss elastic modulus at each angular frequency and loss tangent tan δ were obtained as calculated values. Among these results, the value of loss tangent tan δ at an angular frequency of 1 rad / s was adopted. The amount of strain was 5%, and the measurement was performed in a nitrogen atmosphere.

  (4) Particle size: Measure the dimensions of the resin pellets in the longitudinal direction and the transverse direction, and calculate their average value. The above measurement was carried out on arbitrary 5 grains, and the average value was defined as the grain size.

(5) Foaming ratio:
The value obtained by dividing the density of the unfoamed product by the apparent density of the foam after 24 hours was taken as the expansion ratio.

(6) Internal void: The cross section of the foam cut to a length of 200 mm was cut in half, and the number of voids (diameter 1.5 mm or more) on the cut surface was confirmed. Five cross sections were confirmed, and the average value of the number of voids per piece was determined based on the writing standard.
◎ ・ ・ ・ 5 or less ○ ・ ・ ・ More than 5 and 7 or less △ ・ ・ ・ More than 7 and 10 or less × ・ ・ ・ More than 10 or extremely communicated

(6) Foam appearance (surface smoothness)
The difference in the outer diameter of the foam cut out to a length of 200 mm (difference between the maximum value and the minimum value at a total of three locations at both ends and the center) was confirmed. Five outer diameters were confirmed, and an average value of five outer diameter differences was determined according to the following criteria.
A ... 0.5 mm or less B ... over 0.5 mm and 0.7 mm or less C ... over 0.7 mm and 1.0 mm or less D ... over 1.0 mm

    Next, resin materials and foaming agents used in Examples and Comparative Examples are shown below.

(A) Thermoplastic elastomer TP-1: Prime TPO R110MP [made by prime polymer, type A hardness 68, MFR (230 ° C., 2.16 kg) 2 g / 10 min TP-2: Versify 3401 [made by Dow Chemical Japan, type A Hardness 72, MFR (230 ° C., 2.16 kg) 8 g / 10 min]

(B) Modified polypropylene resin MP-1: 100 parts by weight of a propylene homopolymer having a melt flow rate of 15 g / 10 min as a linear polypropylene resin, and t-butyl peroxyisopropyl carbonate 0.7 as a radical polymerization initiator A mixture of parts by weight is supplied from a hopper to a 45 mmφ twin-screw extruder (L / D = 40) at 70 kg / hour and melt-kneaded at a cylinder temperature of 200 ° C. and a rotational speed of 150 rpm. By supplying 0.6 parts by weight (0.42 kg / hr) of isoprene monomer as a compound using a metering pump, melt-kneading in the twin screw extruder, and cooling and shredding the extruded strand with water The obtained modified polypropylene resin (melt flow rate 3 g / 10 min, melt tension 18 cN, tan δ 1.1, particles (Diameter 3.5mm)
MP-2: A propylene homopolymer having a melt flow rate of 45 g / 10 min is used as a linear polypropylene resin, the blending amount of t-butylperoxyisopropyl carbonate is 0.6 parts by weight, and the supply amount of isoprene monomer is 0.00. A modified polypropylene resin obtained in the same manner as MP-1 except that it was changed to 8 parts by weight (melt flow rate 6 g / 10 min, melt tension 12 cN, tan δ 1.3, particle size 3.2 mm)
MP-3: Modified polypropylene obtained in the same manner as MP-2, except that the amount of t-butylperoxyisopropyl carbonate was changed to 1.0 part by weight and the amount of isoprene monomer supplied was changed to 0.5 part by weight. Resin (melt flow rate 22 g / 10 min, melt tension 5.1 cN, tan δ 1.7, particle size 3.2 mm)
MP-4: Modified polypropylene obtained in the same manner as MP-2, except that the amount of t-butylperoxyisopropyl carbonate was changed to 1.0 part by weight and the amount of isoprene monomer supplied was changed to 0.3 part by weight. Resin (melt flow rate 56 g / 10 min, melt tension 4.8 cN, tan δ 2.5, particle size 3.0 mm)
MP-5: A modified polypropylene resin (melt flow rate 3 g / 10 min, melt tension 18 cN, tan δ1) obtained in the same manner as MP-1, except that the conditions for cutting the strands were changed and the particle size was increased. .1, particle size 4.2 mm)
MP-6: “PF-814” manufactured by Sun Allomer (melt flow rate 3 g / 10 min, melt tension 18 cN, tan δ 1.2, particle size 4.3 mm)

(C) Foaming agent BA-1: Chemical blowing agent master batch [manufactured by Eiwa Kasei Co., Ltd., Polyslen EE275F, decomposition gas amount 40 ml / g]

Example 1
The thermoplastic elastomer and the modified polypropylene resin were dry blended at the composition ratio shown in Table 1 to obtain a thermoplastic elastomer composition for extrusion foam molding.
To 100 parts by weight of the composition, 10 parts by weight of chemical foaming agent BA-1 is added to a tandem type extruder (first stage extruder cylinder diameter is 40 mmφ, second stage extruder cylinder diameter is 50 mmφ). After being fed and melted at 200 ° C. in the first stage extruder, this was cooled down to a resin temperature of 145 ° C. in the second stage extruder, and then under atmospheric pressure from a circular die (4 mmφ × 25 mm) To give a round bar-like extruded foam.
Table 1 shows the physical properties of the obtained extruded foam.

(Example 2)
Extruded foam was obtained in the same manner as in Example 1 except that the modified polypropylene resin was changed to MP-2. Table 1 shows the physical properties of the obtained extruded foam.

(Example 3)
Extruded foam was obtained in the same manner as in Example 1 except that the modified polypropylene resin was changed to MP-3 and the composition ratio shown in Table 1 was changed. Table 1 shows the physical properties of the obtained extruded foam.

Example 4
Extruded foam was obtained in the same manner as in Example 1 except that the modified polypropylene resin was changed to MP-4 and changed to the composition ratio shown in Table 1. Table 1 shows the physical properties of the obtained extruded foam.

(Example 5)
Extruded foam was obtained in the same manner as in Example 1 except that the modified polypropylene resin was changed to MP-5. Table 1 shows the physical properties of the obtained extruded foam.

(Comparative Example 1)
Extruded foam was obtained in the same manner as in Example 1 except that the thermoplastic elastomer was changed to TP-2 and the modified polypropylene resin was changed to MP-6. Table 1 shows the physical properties of the obtained extruded foam.

(Comparative Example 2)
Extruded foam was obtained in the same manner as in Comparative Example 1 except that the modified polypropylene resin was changed to MP-2 and changed to the composition ratio shown in Table 1. Table 1 shows the physical properties of the obtained extruded foam.

(Comparative Example 3)
Extruded foam was obtained in the same manner as in Example 1 except that the modified polypropylene resin was not used. Table 1 shows the physical properties of the obtained extruded foam.

Claims (8)

A thermoplastic elastomer (A) having a melt flow rate (MFR (A), 230 ° C., 2.16 kg) of 20 g / 10 min or less and a type A hardness of 40 to 80 wt%, and the following (a) A thermoplastic elastomer composition for extrusion foam molding comprising 3 to 50% by weight of a modified polypropylene resin (B) satisfying the characteristics of ( c ).
(A) Melt flow rate (MFR (B), 230 ° C., 2.16 kg) is 3 to 30 g / 10 minutes, and MFR (B)> MFR (A)
(B) 200 melt tension at ° C. or more 0.5cN (c) 200 ℃ loss tangent tanδ storage is the ratio of the elastic modulus and the loss modulus at angular frequency 1 rad / s in a dynamic viscoelasticity measurement at the 2 . 0 hereinafter 2. The thermoplastic elastomer composition for extrusion foam molding according to claim 1, wherein the melt flow rate (MFR (B), 230 ° C., 2.16 kg) is 4.5 to 22 g / 10 minutes. The thermoplastic elastomer composition for extrusion foam molding according to claim 1 or 2, wherein the melt tension at 200 ° C is 0.5 to 15 cN. The thermoplastic elastomer composition for extrusion foam molding according to any one of claims 1 to 3, wherein the particle size of (B) is 4 mm or less. The thermoplastic elastomer composition for extrusion foam molding according to any one of claims 1 to 4, wherein MFR (B) / MFR (A)> 3. The thermoplastic elastomer composition for extrusion foam molding according to any one of claims 1 to 5 , wherein MFR (A): 0.1 to 10 and MFR (B): 4.5 or more. The extrusion polypropylene molding according to any one of claims 1 to 6 , wherein the modified polypropylene resin is obtained by melt-mixing a linear polypropylene resin, a radical polymerization initiator, and a conjugated diene compound. Thermoplastic elastomer composition. An extrusion foam molded article obtained by extrusion foaming the elastomer composition for extrusion foam molding according to any one of claims 1 to 7 .