Foam and method for producing the same

Abstract

To provide a foam that can achieve warm sensation and cushioning property.SOLUTION: A foam containing a resin component consisting of thermoplastic resin and / or a crosslinked body thereof, and zirconium oxide is prepared. A ratio of the zirconium oxide is 0.01 to 8 pts.mass for the resin component 100 pts.mass. In the foam, the zirconium oxide is dispersed in the resin component as a dispersion phase at the average diameter of 10 μm or less. An expansion ratio of the foam is 10 times or more. The average diameter of the dispersion phase may be less than 100nm. The thermoplastic resin contains olefin-based resin. The resin component may be polyethylene-based resin. The foam further contains silicon oxide. The zirconium oxide may be localized in the vicinity of a wall surface of a void and / or a skin layer. The foam may be a warm-sensation foam which is capable of releasing heat.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a foam having thermosensitivity and cushioning properties and a method for producing the same.

Background Art

[0002] In the fields of daily necessities (such as kotatsu mats, kitchen mats, etc.), outdoor goods, disaster prevention goods, pet goods, bedding goods, etc., as temperature-sensitive goods having thermosensitivity (characteristics capable of imparting warmth) and cushioning properties ( cushioning properties), a foamed sheet with an aluminum foil laminated thereon is widely used. Examples of the usage method of this foamed sheet include a method of reflecting near-infrared rays or far-infrared rays, which are heat sources, to exhibit thermosensitivity.

[0003] Japanese Patent Application Laid-Open No. 2019-38198 (Patent Document 1) discloses a foamed resin laminate including a phenolic resin foam layer and a surface layer provided on at least one surface of the foam layer via a flexible facing material, wherein the surface layer is a metal layer covered with a protective layer. This document describes that the phenolic resin foam layer is adopted in various fields as a heat insulating material, and in the examples, it is described that it is installed on a sloping roof and the workability is improved.

[0004] Japanese Patent Application Laid-Open No. 2017-141342 (Patent Document 2) discloses a foam including a thermoplastic resin and an elastomer and composed of a skin region and a core region. This document exemplifies a number of inorganic compounds as fillers, which are optional components that the foamed molded body may contain, but the particle size is not described and is not compounded even in the examples.

[0005] Japanese Patent Application Laid-Open No. 2019-38997 (Patent Document 3) discloses a tree used for heat dissipation of electronic devices​​​​ As a fat sheet, a foamed resin sheet with an adhesive layer is disclosed. In this document, the adhesive layer is described as a thermally conductive adhesive containing first thermally conductive particles with an average particle diameter of 0.1 μm or more and less than 5 μm and second thermally conductive particles with an average particle diameter of 5 to 30 μm, and it is described that the adhesive layer may be a foam. In the examples, as the adhesive layer, a non-foamed adhesive layer containing aluminum hydroxide powder with an average particle diameter of 1 μm and aluminum hydroxide powder with an average particle diameter of 8 μm is prepared.

[0006] On the other hand, in order to impart temperature sensitivity to the foamed resin itself, a foamed sheet added with a metal oxide that emits far-infrared rays has also been proposed.

[0007] Japanese Utility Model Registration No. 3113678 (Patent Document 4) discloses a blood flow promoting sheet having a structure in which polyethylene resin is mixed with aluminum oxide or titanium oxide or zirconium oxide alone or in combination thereof, and having at least a sheet-like crosslinked foam on the surface.

[0008] Japanese Patent Application Laid-Open No. 2003-327733 (Patent Document 5) discloses a first step of firing inorganic natural mineral colomanite to produce fired colomanite, and mixing the fired colomanite in an amount of about 5 parts, 10 to 20 parts of a metal oxide, and 100 parts of a polyethylene resin, adding at least a foaming agent thereto, kneading, and foaming to obtain a polyethylene foam as a second step, and a third step of slicing the polyethylene foam obtained in the second step to an arbitrary thickness to form a sheet. A method for manufacturing a sheet is disclosed, which is characterized by including the above steps.

[0009] Japanese Patent Publication No. 2004-518793 (Patent Document 6) discloses a foaming composition containing surface-modified nanoparticles of less than about 100 nm in a vehicle. In the examples, nanosilica modified with a silane coupling agent is used as the surface-modified nanoparticles. [Prior Art Documents] [Patent Documents]

[0010] [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2019-38198 [Patent Document 2] Japanese Unexamined Patent Application Publication No. 2017-141342 [Patent Document 3] Japanese Unexamined Patent Application Publication No. 2019-38997 [Patent Document 4] Utility Model Registration No. 3113678 [Patent Document 5] Japanese Unexamined Patent Application Publication No. 2003-327733 [Patent Document 6] Japanese Patent Publication No. 2004-518793 [Summary of the Invention] [Problems to be Solved by the Invention]

[0011] However, none of Patent Documents 1 to 3 describe using the foam as a temperature-sensitive good.

[0012] When the foam of Patent Document 1 is used as a temperature-sensitive good, since a metal foil is laminated on the foam, the flexibility and handleability are low, and it is difficult to mold it into a non-standard shape other than a sheet shape.

[0013] On the other hand, in Patent Documents 2 and 3, inorganic particles are blended into the foam as a filler or a heat conductor. Although it has been described to do so, the foam containing the inorganic particles has not been prepared.

[0014] In Patent Documents 4 and 5, since a large amount of metal oxide is contained, the mechanical properties of the foam deteriorate. Moreover, the particle size of the metal oxide is unknown. In addition, in Patent Document 5, since it is a so-called mold-foamed foam, it is difficult to knead the foam raw materials, and a foam in which the metal oxide is uniformly dispersed cannot be obtained.

[0015] In addition, in Patent Documents 6 and 7, the expansion ratio is unknown and the temperature sensitivity is not described. Furthermore, in the applications of Patent Document 7, there are many low-expansion foams.

[0016] Therefore, an object of the present invention is to provide a foam capable of achieving both temperature sensitivity and cushioning properties (cushioning properties) and a method for producing the same.

[0017] Another object of the present invention is to provide a foam that can be easily molded into various three-dimensional shapes and a method for producing the same.

[0018] Still another object of the present invention is to provide a foam having excellent flexibility and touch and a method for producing the same.

[0019] Another object of the present invention is to provide a foam having excellent mechanical properties and heat retention and a method for producing the same.

Means for Solving the Problems

[0020] As a result of intensive studies to achieve the above problems, the present inventors have found that by finely dispersing a small amount of zirconium oxide in the foam, temperature sensitivity can be exhibited even in a simple and homogeneous structure, and the cushioning property (cushioning property) is not impaired, and the present invention has been completed. ​

[0021] That is, the foam of the present invention is a resin composition comprising a thermoplastic resin and / or a crosslinked product thereof. and zirconium oxide, wherein the proportion of said zirconium oxide is greater than that of said resin. 0.01 to 8 parts by mass per 100 parts by mass of the oil component, The zirconium oxide is dispersed as a dispersed phase in the mixture, and the average diameter of the dispersed phase is 10 μm or less. The foam may have an expansion ratio of 10 times or more. The resin component may be a polyethylene-based resin. The foam may further contain silicon oxide (particularly, silica gel). The zinc may be localized near the walls and / or skin of the voids. The foam may be a warm foam capable of releasing heat.

[0022] The present invention relates to a method for foaming a foamable resin composition comprising a raw resin component and zirconium oxide. The foamable resin composition also includes a foaming agent as a matrix. The raw material resin component may have a dispersed phase in which zirconium oxide is dispersed. The foamable resin composition may have an average diameter of 100 nm or less. In the first raw material resin component, zirconium oxide is dispersed as a dispersed phase in molecular or atomic units. The master batch may be combined with the second raw material resin component. Effect of the Invention

[0023] In the present invention, a small amount of zirconium oxide is finely dispersed in the foam, so that the zirconium oxide is not separated from the foam. There is no need to form a layer to express the warmth sensation, and the structure is simple and homogeneous (simple single layer structure). Even if it is a foam, it can achieve both temperature sensitivity and cushioning (shock absorption). In addition, it can be easily molded into various three-dimensional shapes, has excellent flexibility, and can improve the texture. Also, since a small amount of zirconium oxide is finely dispersed, it also has excellent mechanical properties. Furthermore, it has heat retention properties because it absorbs and emits far-infrared rays by zirconium oxide, rather than expressing temperature sensitivity by reflection of any aluminum foil.

BEST MODE FOR CARRYING OUT THE INVENTION

[0024] [Resin component] The foam of the present invention contains, as a resin component, a thermoplastic resin or a crosslinked product thereof.

[0025] Examples of the thermoplastic resin include olefin resins, styrene resins, vinyl chloride resins, vinyl acetate resins, polyvinyl alcohol resins, acrylic resins, polyacetal resins, polyester resins, polycarbonate resins, polyamide resins, and thermoplastic elastomers containing constituent components of these resins. These thermoplastic resins can be used alone or in combination of two or more. Among these thermoplastic resins, a thermoplastic resin containing an olefin resin is preferable.

[0026] The olefin resin may be a polymer mainly composed of olefin units, and the olefin resin includes homopolymers or copolymers of olefins.

[0027] Examples of the olefin include ethylene, 1-propylene, 1-butene, isobutene, 1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetrade cene, 1-hexadecene, 1-octadecene, 1-eicosene, etc., C 2-20 α-linear​​​​​​​​​ Linear olefins; C linear olefins such as 3-methyl-1-butene, 2-methyl-1-pentene, 3-methyl-1- pentene, 3-ethyl-1-pentene, 4-methyl-1-pentene, 4-methyl-1-hexene, 4,4-dimethyl-1-hexene, 4,4-dimethyl-1-pentene, 4-ethyl-1-hexene, 3-ethyl-1-hexene, etc. 2-20 α-branched linear olefins ; C cycloolefins such as cyclobutene, cyclopentene, cycloheptene, cyclooctene, etc. 4-12 cyc cloolefins; polycyclic olefins such as 2-norbornene, 5-methyl-2-norbornene, 5,5-dimethyl- 2-norbornene, etc. may be mentioned.

[0028] These olefins can be used alone or in combination of two or more. Among these α-C 2-8 olefins are preferred, α-C 2-4 olefins are more preferred, and ethylene and / or propylene are most preferred.

[0029] The olefin resin may be a copolymer of the olefin and a comonomer copolymerizable therewith. Examples of the comonomer copolymerizable therewith include ethylenically unsaturated carboxylic acids, (meth)acrylic acid esters, vinyl carboxylates, polymerizable nitrile compounds, aromatic vinyls, conjugated dienes, non-conjugated dienes, etc.

[0030] As the ethylenically unsaturated carboxylic acids, ethylenically unsaturated carboxylic acids and their acid anhydrides can be used, for example, (meth)acrylic acid, (anhydrous) maleic acid, fumaric acid, itaconic acid, citraconic acid, crotonic acid, isocrotonic acid, mesaconic acid, angelic acid, etc. may be mentioned.

[0031] Examples of the (meth)acrylate esters include methyl acrylate, ethyl acrylate , C alkyl (meth)acrylate esters such as methyl methacrylate, glycidyl 1-6 (meth)acrylate, and the like. Examples of the vinyl carboxylate esters include saturated vinyl carboxylate esters such as vinyl acetate and vinyl propionate.

[0032] Examples of the polymerizable nitrile compounds include (meth)acrylonitrile and the like .

[0033] Examples of the aromatic vinyl compounds include styrene, vinyltoluene, α-methylstyrene, etc.

[0034] Examples of the conjugated dienes include butadiene, isoprene, pentadiene, 2,3-di methylbutadiene, and the like.

[0035] Examples of the non-conjugated dienes include 1,4-hexadiene, 1,6-octadiene, 2 -methyl-1,5-hexadiene, 4-methyl-1,4-hexadiene, 5-methyl-1

[0036] ,4-hexadiene, dicyclopentadiene, 5-vinylnorbornene, 5-ethylidene -2-norbornene, and the like. ,4-hexadiene, dicyclopentadiene, 5-vinylnorbornene, 5-ethylidene -2-norbornene, and the like.

[0037] These copolymerizable monomers can be used alone or in combination of two or more. The proportion of the copolymerizable monomers is 0 to 50 mol%, preferably 0.1 to 30 mol%, more preferably 1 to 10 mol% in all the monomers.

[0038] The said copolymer (copolymer of olefins with each other and copolymer of olefin and copolymerizable monomer) includes random copolymer, alternating copolymer, block copolymer, graft copolymer, but usually is random copolymer or alternating copolymer. These olefin resins can be used alone or in combination of two or more kinds. Among these olefin resins, from the viewpoints of foamability etc., poly C

[0039] olefin resins (especially polyethylene resins) are preferable. Examples of the polyethylene resin include homopolymers of ethylene such as low density polyethylene (LDPE), linear low density polyethylene (LLDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE); copolymers mainly composed of ethylene such as ethylene-propylene copolymer, ethylene- 2-3 butene-1 copolymer, ethylene-propylene-butene-1 copolymer, ethylene-(4-methylpentene-1) copolymer, ethylene-vinyl acetate copolymer (EVA resin), ethylene-methyl methacrylate copolymer, etc. These polyethylene resins can be used alone or in combination of two or more kinds. Among these polyethylene resins, from the viewpoints of foamability etc., LDPE, LLDPE, EVA

[0040] resin, etc. are preferable. The number average molecular weight of the polyethylene resin is, for example, 10,000 to 300,000, preferably 15,000 to 2 00,000, more preferably 20,000 to 100,000. The molecular weight is measured at a measurement temperature of 140 °C by gel permeation chromatography (GPC method) with orthodichloro as the solvent. These olefin resins can be used alone or in combination of two or more kinds. Among these olefin resins, from the viewpoints of foamability etc., poly C olefin resins (especially polyethylene resins) are preferable. Examples of the polyethylene resin include homopolymers of ethylene such as low density polyethylene (LDPE), linear low density polyethylene (LLDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE); copolymers mainly composed of ethylene such as ethylene-propylene copolymer, ethylene-

[0041] butene-1 copolymer, ethylene-propylene-butene-1 copolymer, ethylene-(4-methylpentene-1) copolymer, ethylene-vinyl acetate copolymer (EVA resin), ethylene-methyl methacrylate copolymer, etc. These polyethylene resins can be used alone or in combination of two or more kinds. Among these polyethylene resins, from the viewpoints of foamability etc., LDPE, LLDPE, EVA resin, etc. are preferable. chromatography method (GPC method), and orthodichlorobenzene as the solvent. It can be measured by universal calibration based on polystyrene using chlorobenzene and a column (Shodex GPC AD-806MS). It can be measured by universal calibration based on polystyrene.

[0042] The melt flow rate (MFR) of the polyethylene resin may be 0.1 g / 10 min or more according to the method (190 °C, load 21.2 N) according to JIS K7210. For example, it may be 0.1 to 60 g / 10 min, preferably 0.2 to 25 g / 10 min, more preferably 0.25 to 8 g / 10 min, and most preferably 0.3 to 5 g / 10 min. If the MFR is too large, there is a risk of deterioration in foamability and strength. Conversely, if it is too small, there is a risk of deterioration in foamability. It is generally known that when the MFR increases, it becomes easier to break the foam due to a decrease in melt tension. However, by adjusting the lower limit of the MFR within the above range, the foamability can be improved. It is generally known that when the MFR increases, it becomes easier to break the foam due to a decrease in melt tension. However, by adjusting the lower limit of the MFR within the above range, the foamability can be improved. It is generally known that when the MFR increases, it becomes easier to break the foam due to a decrease in melt tension. However, by adjusting the lower limit of the MFR within the above range, the foamability can be improved. It is generally known that when the MFR increases, it becomes easier to break the foam due to a decrease in melt tension. However, by adjusting the lower limit of the MFR within the above range, the foamability can be improved.

[0043] The melting point (DSC method) of the polyethylene resin is, for example, 80 to 150 °C, preferably 90 to 140 °C, more preferably 100 to 130 °C. The Vicat softening point of the polyethylene resin is, for example, 70 to 140 °C, preferably 80 to 130 °C, more preferably 90 to 1 20 °C. The Vicat softening point of the polyethylene resin is, for example, 70 to 140 °C, preferably 80 to 130 °C, more preferably 90 to 120 °C.

[0044] Examples of the polypropylene resin include polypropylene which is a homopolymer of propylene; copolymers mainly composed of propylene such as propylene-ethylene copolymer, propylene-(meth)acrylic acid copolymer, propylene-ethylene-butene-1, etc. Examples of the polypropylene resin include polypropylene which is a homopolymer of propylene; copolymers mainly composed of propylene such as propylene-ethylene copolymer, propylene-(meth)acrylic acid copolymer, propylene-ethylene-butene-1, etc. Examples of the polypropylene resin include polypropylene which is a homopolymer of propylene; copolymers mainly composed of propylene such as propylene-ethylene copolymer, propylene-(meth)acrylic acid copolymer, propylene-ethylene-butene-1, etc. These polypropylene resins can be used alone or in combination of two or more. Among these polypropylene resins, polypropylene and propylene-ethylene copolymer are preferred. preferred.

[0045] The number average molecular weight of the polypropylene-based resin is, for example, from 10,000 to 500,000, preferably from 15,000 to 300,000, more preferably from 20,000 to 100,000. The number average molecular weight of the polypropylene-based resin can be measured by gel permeation chromatography (GPC method). The above-mentioned number average molecular weight of the polypropylene-based resin can be measured under the same conditions as the measurement method of the number average molecular weight of the polyethylene-based resin.

[0046] The melting point (DSC method) of the polypropylene-based resin is, for example, from 120 to 180 °C, preferably from 1 30 to 175 °C, more preferably from 140 to 170 °C. The Vicat softening point of the polypropylene-based resin is, for example, from 110 to 170 °C, preferably from 120 to 165 °C, more preferably from 130 to 160 °C.

[0047] The MFR of the polypropylene-based resin may be 0.1 g / 10 min or more according to the method according to JIS K7210 (230 °C, load 21.2 N), for example, from 0.1 to 50 g / 10 min preferably from 0.2 to 30 g / 10 min, more preferably from 0.25 to 10 g / 10 min, most preferably from 0.3 to 5 g / 10 min. If the MFR is too small or conversely too large, there is a risk of deterioration in foamability and strength.

[0048] When the thermoplastic resin contains an olefin-based resin, the thermoplastic resin may be the olefin-based resin alone or a combination of the olefin-based resin and a thermoplastic resin other than the olefin-based resin (other thermoplastic resin). As the other thermoplastic resin to be combined with the olefin-based resin, a styrene-based resin is preferable from the viewpoint of improving the rigidity of the foam, and the foam From the viewpoint of improving flexibility, thermoplastic elastomers (for example, olefin-based thermoplastic elastomers, styrene-based thermoplastic elastomers, etc.) are preferred. The mass ratio of the olefin-based resin to other thermoplastic resins can be selected from the range of olefin-based resin / other thermoplastic resin = 100 / 0 to 10 / 90 (for example, 100 / 0 to 50 / 50). When combined with other thermoplastic resins, olefin-based resin / other thermoplastic resin = 99 / 1 to 30 / 70, preferably 98 / 2 to 50 / 50, more preferably 95 / 5 to 70 / 30, and most preferably 93 / 7 to 80 / 20. The proportion of the olefin-based resin is preferably 50% by mass or more in the thermoplastic resin, more preferably 80% by mass or more (especially 90% by mass or more), and may be 100% by mass (olefin-based resin only). If the proportion of the olefin-based resin is too small, the foamability may decrease.

[0049] The mass ratio of the olefin-based resin to other thermoplastic resins can be selected from the range of olefin-based resin / other thermoplastic resin = 100 / 0 to 10 / 90 (for example, 100 / 0 to 50 / 50). When combined with other thermoplastic resins, olefin-based resin / other thermoplastic resin = 99 / 1 to 30 / 70, preferably 98 / 2 to 50 / 50, more preferably 95 / 5 to 70 / 30, and most preferably 93 / 7 to 80 / 20. The proportion of the olefin-based resin is preferably 50% by mass or more in the thermoplastic resin, more preferably 80% by mass or more (especially 90% by mass or more), and may be 100% by mass (olefin-based resin only). If the proportion of the olefin-based resin is too small, the foamability may decrease. The mass ratio of the olefin-based resin to other thermoplastic resins can be selected from the range of olefin-based resin / other thermoplastic resin = 100 / 0 to 10 / 90 (for example, 100 / 0 to 50 / 50). When combined with other thermoplastic resins, olefin-based resin / other thermoplastic resin = 99 / 1 to 30 / 70, preferably 98 / 2 to 50 / 50, more preferably 95 / 5 to 70 / 30, and most preferably 93 / 7 to 80 / 20. The proportion of the olefin-based resin is preferably 50% by mass or more in the thermoplastic resin, more preferably 80% by mass or more (especially 90% by mass or more), and may be 100% by mass (olefin-based resin only). If the proportion of the olefin-based resin is too small, the foamability may decrease. The mass ratio of the olefin-based resin to other thermoplastic resins can be selected from the range of olefin-based resin / other thermoplastic resin = 100 / 0 to 10 / 90 (for example, 100 / 0 to 50 / 50). When combined with other thermoplastic resins, olefin-based resin / other thermoplastic resin = 99 / 1 to 30 / 70, preferably 98 / 2 to 50 / 50, more preferably 95 / 5 to 70 / 30, and most preferably 93 / 7 to 80 / 20. The proportion of the olefin-based resin is preferably 50% by mass or more in the thermoplastic resin, more preferably 80% by mass or more (especially 90% by mass or more), and may be 100% by mass (olefin-based resin only). If the proportion of the olefin-based resin is too small, the foamability may decrease. The mass ratio of the olefin-based resin to other thermoplastic resins can be selected from the range of olefin-based resin / other thermoplastic resin = 100 / 0 to 10 / 90 (for example, 100 / 0 to 50 / 50). When combined with other thermoplastic resins, olefin-based resin / other thermoplastic resin = 99 / 1 to 30 / 70, preferably 98 / 2 to 50 / 50, more preferably 95 / 5 to 70 / 30, and most preferably 93 / 7 to 80 / 20. The proportion of the olefin-based resin is preferably 50% by mass or more in the thermoplastic resin, more preferably 80% by mass or more (especially 90% by mass or more), and may be 100% by mass (olefin-based resin only). If the proportion of the olefin-based resin is too small, the foamability may decrease. The mass ratio of the olefin-based resin to other thermoplastic resins can be selected from the range of olefin-based resin / other thermoplastic resin = 100 / 0 to 10 / 90 (for example, 100 / 0 to 50 / 50). When combined with other thermoplastic resins, olefin-based resin / other thermoplastic resin = 99 / 1 to 30 / 70, preferably 98 / 2 to 50 / 50, more preferably 95 / 5 to 70 / 30, and most preferably 93 / 7 to 80 / 20. The proportion of the olefin-based resin is preferably 50% by mass or more in the thermoplastic resin, more preferably 80% by mass or more (especially 90% by mass or more), and may be 100% by mass (olefin-based resin only). If the proportion of the olefin-based resin is too small, the foamability may decrease. The mass ratio of the olefin-based resin to other thermoplastic resins can be selected from the range of olefin-based resin / other thermoplastic resin = 100 / 0 to 10 / 90 (for example, 100 / 0 to 50 / 50). When combined with other thermoplastic resins, olefin-based resin / other thermoplastic resin = 99 / 1 to 30 / 70, preferably 98 / 2 to 50 / 50, more preferably 95 / 5 to 70 / 30, and most preferably 93 / 7 to 80 / 20. The proportion of the olefin-based resin is preferably 50% by mass or more in the thermoplastic resin, more preferably 80% by mass or more (especially 90% by mass or more), and may be 100% by mass (olefin-based resin only). If the proportion of the olefin-based resin is too small, the foamability may decrease. The mass ratio of the olefin-based resin to other thermoplastic resins can be selected from the range of olefin-based resin / other thermoplastic resin = 100 / 0 to 10 / 90 (for example, 100 / 0 to 50 / 50). When combined with other thermoplastic resins, olefin-based resin / other thermoplastic resin = 99 / 1 to 30 / 70, preferably 98 / 2 to 50 / 50, more preferably 95 / 5 to 70 / 30, and most preferably 93 / 7 to 80 / 20. The proportion of the olefin-based resin is preferably 50% by mass or more in the thermoplastic resin, more preferably 80% by mass or more (especially 90% by mass or more), and may be 100% by mass (olefin-based resin only). If the proportion of the olefin-based resin is too small, the foamability may decrease.

[0050] In applications where durability is required, etc., the resin component may be a crosslinked body of a thermoplastic resin. For the crosslinked body, a conventional crosslinked body can be used according to the type of the thermoplastic resin. When the thermoplastic resin is an olefin-based resin, the crosslinked body may be a conventional olefin resin crosslinked body, for example, a water crosslinked body, a chemical crosslinked body, a radiation crosslinked body, or an electron beam crosslinked body. Among these, from the viewpoints of crosslinkability and productivity, etc., a water crosslinked body is preferred. The water crosslinked body may be a water crosslinked body of an olefin-based resin having a hydrolyzable condensable silyl group (water crosslinkable silyl group) that can be crosslinked with water. It may also be a crosslinked body of a polymer obtained by using a monomer having a hydrolyzable condensable silyl group as a monomer constituting the main chain. Among these, from the viewpoints of crosslinkability and productivity, etc., a water crosslinked body is preferred. The water crosslinked body may be a water crosslinked body of an olefin-based resin having a hydrolyzable condensable silyl group (water crosslinkable silyl group) that can be crosslinked with water. It may also be a crosslinked body of a polymer obtained by using a monomer having a hydrolyzable condensable silyl group as a monomer constituting the main chain.

[0051] The water crosslinked body may be a water crosslinked body of an olefin-based resin having a hydrolyzable condensable silyl group (water crosslinkable silyl group) that can be crosslinked with water. It may also be a crosslinked body of a polymer obtained by using a monomer having a hydrolyzable condensable silyl group as a monomer constituting the main chain. The water crosslinked body may be a water crosslinked body of an olefin-based resin having a hydrolyzable condensable silyl group (water crosslinkable silyl group) that can be crosslinked with water. It may also be a crosslinked body of a polymer obtained by using a monomer having a hydrolyzable condensable silyl group as a monomer constituting the main chain. The water crosslinked body may be a water crosslinked body of an olefin-based resin having a hydrolyzable condensable silyl group (water crosslinkable silyl group) that can be crosslinked with water. It may also be a crosslinked body of a polymer obtained by using a monomer having a hydrolyzable condensable silyl group as a monomer constituting the main chain. A polymer obtained by graft-polymerizing a monomer having a hydrolyzable and condensable silyl group on the main chain of a resin may be used. As such a water-crosslinked olefin resin, for example, those described in JP-A-2016 -37551 and JP-A-2016-37552 can be used .

[0052] [Zirconium oxide] The foam of the present invention contains zirconium oxide (zirconia or zirconium dioxide) that can impart temperature sensitivity to the foam. Since zirconium oxide has the effect of absorbing and emitting far-infrared rays, temperature sensitivity such as heat retention can be imparted to the foam. Further, in the present invention, by including zirconium oxide as a dispersed phase in the resin component, temperature sensitivity can be imparted without impairing the cushioning property and flexibility of the foam. In particular, when zirconium oxide is finely dispersed as a dispersed phase in the resin component as a matrix, even in a small amount, high temperature sensitivity can be imparted to the foam, and high foamability and mechanical properties can also be imparted . The average diameter of the dispersed phase (zirconium oxide) finely dispersed in the matrix is preferably 10 μm or less (for example, about 0.01 to 10 μm), for example, 0.1 to 5 μm, preferably 0.3

[0053] to 3 μm, more preferably 0.5 to 2 μm, and most preferably 1 to 1.5 μm. The average diameter of the dispersed phase may be in the nanometer size, for example, 100 nm or less, preferably 50 nm or less, more preferably 30 nm or less (for example, about 0.1 to 10 nm ). When the dispersed phase has an anisotropic shape, the diameter of each dispersed phase means the average value of the major axis and the minor axis . . Preferably, it is 0.1 to 10 nm).

[0054] ​Furthermore, the dispersed phase (zirconium oxide) finely dispersed in the matrix is preferably localized near the wall surface of the void and / or the skin layer because it can improve the temperature sensitivity.

[0055] In this specification and the claims, the average diameter and dispersion state of the dispersed phase can be measured based on the observation with a scanning electron microscope (SEM) and elemental analysis (EDS elemental analysis) using an energy dispersive X-ray spectrometer, and specifically, they can be measured by the method described in the examples below.

[0056] From the viewpoints of temperature sensitivity and dispersibility, etc., zirconium oxide that has not been surface-treated is preferable.

[0057] In the present invention, since the proportion of zirconium oxide is relatively small, the foamability and mechanical properties of the foam can be improved. Specifically, the proportion of zirconium oxide in the foam may be 10% by mass or less (for example, about 0.001 to 10% by mass), but even a small amount can exhibit functionality. Therefore, from the viewpoint of improving the above-mentioned properties inherent to the foam, it may be 5% by mass or less (for example, 0.01 to 5% by mass), for example, 0.03 to 5% by mass (for example, 0.05 to 4% by mass), preferably 0.1 to 3% by mass (for example, 0.2 to 2% by mass), more preferably 0.3 to 1. 5% by mass, most preferably 0.5 to 1% by mass. The proportion of zirconium oxide is 0.01 to 8 parts by mass with respect to 100 parts by mass of the resin component, preferably 0.01 to 5 parts by mass, more preferably 0.1 to 3 parts by mass, still more preferably 0.3 to 2 parts by mass, and most preferably 0 .5 to 1.5 parts by mass. If the proportion of zirconium oxide is too large, there is a risk that the foamability and mechanical properties of the foam will deteriorate.

[0058] [Silicon Oxide]​​​​​​​​​ In addition to the resin component and zirconium oxide, the foam of the present invention may further contain silicon oxide (silica or silicon dioxide) in view of improving the dispersibility of zirconium oxide.

[0059] Examples of silicon oxide (silica) include dry silica such as fumed silica (dry process white carbon); wet silica such as colloidal silica, silica gel, and precipitated silica (wet process white carbon). These silicon oxides can be used alone or in combination of two or more. The silicon oxide may be surface-treated silica. Among these silicas, silica gel is preferred, and type B silica gel is particularly preferred.

[0060] The particle size of silicon oxide, as particles passing through a mesh by the sieving method, is, for example, 1000 μm or less, preferably 500 μm or less, more preferably 100 μm or less, and most preferably 50 μm or less. If the particle size of silica is too large, the mechanical properties of the foam may deteriorate.

[0061] Silicon oxide may be either non-porous or porous, but the BET method nitrogen adsorption specific surface area is, for example, 100 to 1000 m / g, preferably 200 to 800 m 2 / g 2 , more preferably 300 to 700 m 2 / g, and most preferably 400 to 600 m 2 / g. If the specific surface area is too large, it may be difficult to disperse uniformly, and if the specific surface area is too small, the mechanical properties of the foam may deteriorate.

[0062] ​​​​​​​​​​​​The proportion of silicon oxide is 10 parts by mass or more with respect to 100 parts by mass of zirconium oxide and may be, for example, 10 to 5000 parts by mass, preferably 50 to 3000 parts by mass, more preferably 100 to 1000 parts by mass, still more preferably 200 to 500 parts by mass, and most preferably 2 50 to 400 parts by mass. If the proportion of silicon oxide is too small, there is a risk that the effect of improving the dispersion property of zirconium oxide will decrease.

[0063] [Blowing agent] The foam of the present invention is obtained by foaming a foamable resin composition containing the resin component and zirconium oxide, and the foamable resin composition may contain a blowing agent.

[0064] As the blowing agent, a conventional blowing agent can be used, and it may be a decomposable blowing agent (chemical blowing agent). However, from the viewpoint of being able to improve the foaming ratio by a simple method, a volatile blowing agent (physical blowing agent) is preferred. Examples of the volatile blowing agent include inorganic blowing agents (such as nitrogen, carbon dioxide, oxygen, air, water, etc.), organic blowing agents (such as aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, chlorinated hydrocarbons, fluorinated hydrocarbons, alcohols, ethers, aldehydes, ketones, etc.). Among these, lower aliphatic hydrocarbons such as butane (n-butane, isobutane, etc.) and pentane (n-pentane, isopentane, etc.) are widely used because of their low cost and low toxicity.

[0065] The proportion of the blowing agent is, for example, 0.01 to 30 parts by mass, preferably 0.1 to 25 parts by mass, more preferably 1 to 20 parts by mass, and most preferably 5 to 15 parts by mass with respect to 100 parts by mass of the resin component.

[0066] [Nucleating agent for foaming] The foam of the present invention may further contain a foaming nucleating agent. Examples of the foaming nucleating agent include silicon compounds (such as talc, silica, zeolite), inorganic acid salts (such as sodium bicarbonate, calcium carbonate, magnesium carbonate, sodium hydrogen carbonate, ammonium carbonate, etc., or carbonates or hydrogen carbonates such as these), organic acids or their salts (such as citric acid, sodium citrate, calcium stearate, aluminum stearate, zinc stearate, etc.), metal oxides (such as zinc oxide, titanium oxide, aluminum oxide, etc.), metal hydroxides (such as aluminum hydroxide, etc.). These foaming nucleating agents can be used alone or in combination of two or more.

[0067] The proportion of the foaming nucleating agent is, for example, 0.01 to 10 parts by mass, preferably 0.05 to 5 parts by mass, more preferably 0.1 to 3 parts by mass, and most preferably 0. 5 to 2 parts by mass with respect to 100 parts by mass of the resin component.

[0068] [Shrinkage inhibitor] The foam of the present invention may further contain a shrinkage inhibitor. Examples of the shrinkage inhibitor include, for example, fatty acid esters (such as esters of C fatty acids and polyhydric alcohols such as palmitic acid mono- to triglyceride, stearic acid mono- to 8-24 triglyceride, etc.), fatty acid amides (such as C 8-24 fatty acid amides such as palmitic acid amide, stearic acid amide, etc.). These shrinkage inhibitors can be used alone or in combination of two or more. .

[0069] The proportion of the shrinkage inhibitor is, for example, 0.01 to 30 parts by mass, preferably 0.05 to 20 parts by mass, more preferably 0.1 to 10 parts by mass, and most preferably​ is 1 to 5 parts by mass.

[0070] [Other additives] The foam of the present invention may further contain conventional additives as other additives. Conventional additives include colorants (such as dyes and pigments), surface smoothing agents, bubble regulators, stabilizers (such as antioxidants, heat stabilizers, ultraviolet absorbers, etc.), viscosity regulators, compatibilizers, dispersants, antistatic agents , antiblocking agents, antifogging agents, fillers (such as calcium carbonate and carbon fiber), lubricants, mold release agents, lubricants, impact improvers, plasticizers, flame retardants, biocides (such as bactericides, bacteriostatic agents, antifungal agents, preservatives, insect repellents, etc.), anti-allergy agents, deodorants, etc. These conventional additives can be used alone or in combination of two or more.

[0071] The total proportion of other additives is, for example, 0.01 to 30 parts by mass, preferably 0.05 to 20 parts by mass, more preferably 0.1 to 10 parts by mass, and most preferably 1 to 5 parts by mass, based on 100 parts by mass of the resin component.

[0072] [Properties of the foam] Although the foam of the present invention contains an inorganic compound that has not been actively added conventionally due to a decrease in foamability, the foamability can be improved. The specific expansion ratio may be 3 times or more (especially 10 times or more), for example, 3 to 100 times, preferably 5 to 80 times, more preferably 10 to 50 times, still more preferably 15 to 40 times, and most preferably 20 to 3 0 times. If the expansion ratio is too low, there is a risk of deterioration in cushioning properties and flexibility.

[0073] The foam of the present invention has a closed-cell and / or open-cell structure, and at least a closed It is preferable that the porous structure contains a vertical cell structure, and the ratio of open cells to the total number of cells (the sum of open cells and closed cells) is 1.0 to 1.0. The open cell ratio, which is the ratio of the bubbles, may be 90% by volume or less, for example, 0.1 to 90% by volume. %, preferably 1 to 80% by volume, more preferably 3 to 50% by volume, and most preferably 5 to If the open cell ratio is too high, the mechanical properties of the foam may be reduced. In the present invention, since zirconium oxide is finely dispersed in the thermoplastic resin, it is difficult to form independent bubbles. Despite the use of zirconium oxide, a common inorganic compound, such high independent porosity was achieved. On the other hand, for applications requiring flexibility, a foam with a high open cell ratio is preferred. For example, the open cell ratio may be more than 90 volume %. For example, the composition of the resin components other than the master batch may be changed. .

[0074] The average cell diameter of the foam of the present invention is, for example, 0.2 to 2 mm, preferably 0.3 to 1.8 mm. m, more preferably 0.4 to 1.6 mm, and most preferably 0.5 to 1.3 mm. If the average cell diameter is too small, it may be difficult to increase the expansion ratio. However, there is a risk of the mechanical properties being deteriorated.

[0075] The foam of the present invention preferably has a skin layer on the surface. The coverage may be 60% by area or more (particularly 80% by area or more), and preferably 90% by area. The skin layer may be 100% by area (the entire surface is the skin layer). It means a non-foamed layer that extends with a substantially uniform thickness on the surface of a foam.

[0076] The average thickness of the skin layer can be selected from the range of about 0.001 to 1 mm. For example, 5 to 0.1 mm, preferably 0.008 to 0.05 mm, more preferably 0.01 to 0.03 mm, and most preferably 0.012 to 0.025 mm. If the average thickness of the skin layer is too thin, there is a risk of reduced handleability, and conversely, if it is too thick, there is a risk of reduced foamability.

[0077] In addition, in this specification and the claims, the foam expansion ratio, the closed cell ratio, the average cell diameter, and the average

[0078] thickness of the skin layer can be measured by the method described in the examples below. The foam of the present invention may be a temperature-sensitive foam capable of releasing heat. In particular, the temperature-sensitive

[0079] [Method for manufacturing the foam] The method for manufacturing the foam of the present invention may be any method for foam molding a foamable resin composition containing a raw resin component (unfoamed thermoplastic resin) and zirconium oxide, and a conventional method can be used. Usually, a method of melt-kneading the resin composition and then performing foam molding

[0080] can be used. As the foamable resin composition, it is preferable to use a foamable resin composition in which zirconium oxide is finely dispersed in the raw resin component. In the present invention, it is particularly preferable to use zirconium oxide as the resin composition before foaming. Since a composition in which zirconium is finely dispersed is used, the obtained foam also contains zirconium oxide. It is possible to finely disperse zirconium oxide on the wall surface of the void and / or near the skin layer. Can be localized.

[0081] As a method for preparing a foamable resin composition in which zirconium oxide is finely dispersed, The raw material resin component (especially olefin-based resin) is heated while the rubber is dissolved or dispersed in a solvent. The resin composition is mixed with the raw resin component, and the solvent is removed in a gaseous state from the resin composition in a molten state. The zirconium oxide used as the raw material is nanometer-sized. Examples of the solvent for dissolving or dispersing zirconium oxide include water and aqueous organic solvents. Solvents (e.g., lower alcohols such as ethanol and isopropanol, ketones such as acetone, etc.) Among these solvents, water is preferred. The concentration of the aqueous dispersion is For example, the content is about 10 to 50 mass %, and preferably about 20 to 40 mass %. If it does, silicon oxide is added to the drive rail together with the zirconium oxide dispersion or separately. Specifically, the foamable resin composition in which zirconium oxide is finely dispersed may be It can be prepared by the method described in JP 2016-216573 A, for example, zirconium oxide. The solution obtained by dispersing the above in the solvent and the raw material resin component are extruded in an extruder (e.g., a single screw or vented extruder). After being fed into a multi-plate twin-screw extruder, the molten raw resin components and the solution are then fed into a multi-plate twin-screw extruder. The molten raw material is fed to a kneading and dispersion section having a rotating kneading plate. The fat component and the solution are uniformly mixed by a rotating kneading plate, and then the mixture is passed through a pressure reduction line. By removing the solvent in a gaseous state from the raw material resin component, zirconium oxide is contained in the raw material resin component. A foaming resin composition in which zirconium oxide is finely dispersed with an average dispersion diameter of less than 100 nm is prepared.

[0082] The obtained foaming resin composition may be directly used for foam molding, or may be used as a masterbatch and then used for foam molding. When the foaming resin composition is used as a masterbatch the resin composition from which the solvent has been removed may be further cooled and prepared in the form of pellets or the like. It is okay.

[0083] When used as a masterbatch, a masterbatch in which zirconium oxide is finely dispersed with an average dispersion diameter of less than 100 nm in the first raw material resin component (especially the first olefin-based resin) and the second raw material resin component which is the remaining raw material resin component (especially the second olefin-based resin) may be melt-kneaded using a conventional melt-kneading machine, for example, a single-screw or vented twin-screw extruder or the like. Also, in the melt-kneading of the masterbatch and the second raw material resin component, other components (foaming agents and, if necessary, foaming nucleating agents, additives, etc.) may be blended. The melt-kneading of the foaming resin composition in which zirconium oxide is finely dispersed may be melt-kneaded using a conventional melt-kneading machine, for example, a single-screw or vented twin-screw extruder or the like. Also, prior to melt-kneading, a conventional method such as a mixer (tumbler, V-type blender, Henschel mixer, Nauta mixer ribbon mixer, mechanochemical device, extrusion mixer, etc.) may be used to premix the masterbatch with the second raw material resin component and other components (foaming agents and, if necessary, foaming nucleating agents, additives, etc.).

[0084]

[0084] As the foam molding method, a conventional method such as an extrusion molding method (for example, T-die method, inflation - A molding method, etc., an injection molding method, etc. can be used. Among these, the extrusion molding method is preferable because a foam having high foamability can be produced with high productivity.

[0085] In the extrusion molding method, as the extruder, for example, a single-screw extruder (for example, a vented extruder, etc.), a twin-screw extruder (for example, a co-rotating twin-screw extruder, a counter-rotating twin-screw extruder, etc.) can be used. From the viewpoint that it is easy to adjust the foaming conditions and a high foaming ratio can be realized, a multi-stage extruder such as a tandem extruder is preferable.

[0086] In the extrusion molding method, the method of introducing the foaming agent is not particularly limited. A decomposable foaming agent (chemical foaming agent) may be previously blended in the foamable resin composition. However, from the viewpoint that the foaming ratio can be improved by a simple method, it is preferable to introduce a volatile foaming agent (physical foaming agent) in the extruder.

[0087] The shape of the discharge port (die lip) of the die is not particularly limited and can be selected according to the target form. For example, a one-dimensional shape such as a rod shape or a string shape, a two-dimensional shape such as a sheet shape, a film shape, or a two-dimensional mesh (net) shape, or a three-dimensional shape such as a block shape, a plate shape, a column shape, a slit shape, an L shape, a U shape, a pipe shape, or a ring shape may be used.

[0088] The extruded foam may be cooled by a conventional method, for example, a cooling method using a cooler. In the cooling method using a cooler, examples of the cooling medium include a compressed air, water (cooling water), and air (blower). Examples of the cooling method include a method of injecting compressed air, a method of cooling with a blower, a method of cooling by spraying water, and a method of cooling using a cooling jacket. The temperature of the cooling medium is, for example, 0 to 60°C, preferably 5 to 5 50°C. It is 5°C, more preferably 10 to 50°C.

[0089] In the method of injecting compressed air, the pressure of the air is, for example, 0.1 to 10 MPa, preferably 0.2 to 5 MPa, more preferably 0.3 to 1 MPa. The injection volume of the compressed air is, for example, 100 to 1000 liters / minute, preferably 200 to 500 liters / minute , more preferably 250 to 400 liters / minute.

[0090] In addition, when the resin component is a cross-linked body of a thermoplastic resin, the obtained extruded foam may be subjected to a cross-linking process. In the cross-linking process of the water cross-linked body, the silyl-modified polyole fin may be cross-linked with moisture in the air. The cross-linking treatment may be carried out in a non-heated state (room temperature of about 15 to 25), but in order to improve productivity, it may also be cross-linked by heating. The heating temperature is, for example, 40 to 100°C, preferably 50 to 80°C, more preferably 55 to 70°C.

[0091] Also, if necessary, the obtained foam (especially sheet-like foam) may be secondary processed [for example, thermoforming such as vacuum forming, pressure air forming, vacuum pressure air forming, match mold forming, etc. (for example, thermoforming using a mold) .

[0092] In addition, the foaming or secondary processing or forming temperature is, for example, 70 to 300°C, preferably 80 to 280°C, more preferably about 85 to 260°C.

[0093] The shape of the foam can be appropriately selected to any shape according to the use, for example, rod shape, sheet shape, three-dimensional shape, etc.

Examples

[0094] The present invention will be described in more detail below based on examples, but the present invention is not limited by these examples. The raw materials used in the examples and comparative examples are as follows, and the properties of the obtained foams were evaluated by the following methods.

[0095] [Raw Materials] LDPE: Low-density polyethylene, "Novatec (registered trademark) LD LF640MA" manufactured by Nippon Polyethylene Co., Ltd., MFR 5 g / 10 min Isobutane (foaming agent): Commercially available product Foaming nucleating agent: Talc, average particle diameter 15 μm Shrinkage inhibitor: "Actibex 32 5" manufactured by Boehringer Ingelheim Chemicals K.K. Zirconium oxide: "SZR-W" manufactured by Sakai Chemical Industry Co., Ltd., average particle size 3 nm Silica: "Toyota Silica Gel B White 400 mesh" manufactured by Toyota Chemical Industry Co., Ltd., particle size 37 μm or less (mesh passing particles by sieving method), BET specific surface area 450 m 2 / g.

[0096] [Areal Density of Foam] A cylindrical foam with a diameter of 74 mm and an inner diameter of 70 mm was cut at 1 m, and an electronic specific gravity meter (Miliage Trading Co., Ltd. "MD200S") was used for measurement (n = 3).

[0097] [Expansion Ratio] The expansion ratio was calculated based on the following formula.

[0098] Expansion ratio (times) = density of resin composition for foam / apparent density of foam.

[0099] [Closed Cell Ratio] The foams obtained in the examples and comparative examples were weighed in advance, placed in water, and then left under a reduced pressure of -4 00 mmHg (gauge pressure) for 1 minute to allow water to penetrate into the closed cell structureIt was returned from the reduced pressure state to atmospheric pressure, and the water adhering to the surface of the foam was removed and the mass was measured. After that, the closed cell ratio was calculated by the following formula (1).

[0100] Closed cell ratio (%) = {(w2 - w1) / d3} / (w1 / d1 - w1 / d2) × 100 (1) (In the formula, w2 is the mass of the foam after water absorption, w1 is the mass of the foam before water absorption, d1 is the apparent density of the foam, d2 is the apparent density of the resin composition used in the foam, and d3 is the density of water at the time of measurement.)

[0101] [Bubble diameter (cell size)] The cross-section of the foam was observed with a scanning electron microscope ("S-4800" manufactured by Hitachi, Ltd.) or a digital microscope (manufactured by Scalar Co., Ltd.), and the bubble diameter in the TD direction cross-section and the bubble diameter in the MD direction cross-section were measured at 10 arbitrary points respectively, and the average value of these 20 points was taken as the bubble diameter. Also, each bubble diameter was taken as the average value of the major axis and the minor axis.

[0102] [Average thickness of the skin layer of the foam] Using an electron microscope (manufactured by Scalar Co., Ltd.) and filing & 2D measurement software ("AR-CNVMF" manufactured by ArtRay Co., Ltd.), the thickness of the skin layer in the TD direction was measured at 10 arbitrary points, and the average value was taken as the average thickness of the skin layer.

[0103] [Thermosensitivity] The foam was cut into a circular shape with a diameter of 3 cm to prepare a sample, and using a Fourier transform infrared spectroscopic analyzer ("FT-IR SpectrumOne Frontier T" manufactured by PerkinElmer), the far-infrared spectroscopic emissivity was measured at a measurement temperature of 40°C.

[0104] Comparative Example 1 Containing 100 parts by mass of LDPE, 1.75 parts by mass of a foaming nucleating agent, and 3.0 parts by mass of an anti-shrinkage agent The resin composition was charged into an extruder, and 8.0 parts by mass of isobutane gas was injected from the middle of this extruder After that, it was cooled to the appropriate foaming temperature, extruded from a ring-shaped mold attached to the tip, and foamed A foam was obtained. The obtained foam was cylindrical with a width of 108 mm and a thickness of 1.83 mm, and had a basis weight of 15 g / m, a foaming ratio of 24.5 times, a closed-cell ratio of 8.8%, a cell size of 1.07 mm, and an average thickness of the skin layer of 0.020 mm

[0105] Example 1 (Preparation of zirconium oxide-containing masterbatch) 3 parts by mass of zirconium oxide and 10 parts by mass of silica. Zirconium oxide was in a slurry with a concentration of 30% by mass and silica was in a dry blend. They were added to 100 parts by mass of LDPE and supplied to an extruder (the extruder described in JP-A-2016-216573), and melt-kneaded under the conditions of a temperature of 150 to 16 0 °C. In the melt-kneading section, a plurality of kneading plates were rotating, and the functional agents dispersed in the polymer and water were uniformly mixed here, and then moisture was removed simultaneously by applying a vacuum (negative pressure) . The melt-kneaded product from which moisture had been removed was supplied to the extrusion section and extruded, cooled, taken out, and pelletized with a pelletizer to obtain a zirconium oxide-containing masterbatch .

[0106] (Production of foam) A resin composition containing 90 parts by mass of LDPE, 10 parts by mass of a zirconium oxide-containing masterbatch, 1. 75 parts by mass of a foaming nucleating agent, and 3.0 parts by mass of an anti-shrinkage agent was charged into an extruder, and 8.0 parts by mass of isobutane gas was injected from the middle of this extruder. After that, it was cooled to the appropriate foaming temperature, and the tip ​​​​It was extruded from a ring-shaped mold attached thereto to obtain a foam. The obtained foam had a width of 97 m m, a cylindrical shape with a thickness of 2.37 mm, a basis weight of 15.8 g / m, a foaming ratio of 24.5 times, a continuous foam ratio of 5.5%, a cell size of 1.45 mm, and an average skin layer thickness of 0.015 mm.

[0107] Example 2 Instead of 90 parts by mass of LDPE and 10 parts by mass of the zirconium oxide-containing masterbatch, 80 parts by mass of LDPE and 20 parts by mass of the zirconium oxide-containing masterbatch were used. Otherwise, a foam was produced in the same manner as in Example 1. The obtained foam had a width of 98 mm and a thickness of 2 .14 mm in a cylindrical shape, a basis weight of 16.2 g / m, a foaming ratio of 23.0 times, a continuous foam ratio of 5.0 %, a cell size of 1.00 mm, and an average skin layer thickness of 0.018 mm.

[0108] Example 3 Instead of 90 parts by mass of LDPE and 10 parts by mass of the zirconium oxide-containing masterbatch, 70 parts by mass of LDPE and 30 parts by mass of the zirconium oxide-containing masterbatch were used. Otherwise, a foam was produced in the same manner as in Example 1. The obtained foam had a width of 100 mm and a thickness of 2.13 mm in a cylindrical shape, a basis weight of 18.0 g / m, a foaming ratio of 17.7 times, a continuous foam ratio of 8. 3%, a cell size of 1.14 mm, and an average skin layer thickness of 0.018 mm.

[0109] Example 4 (Preparation of zirconium oxide-containing masterbatch) A zirconium oxide-containing masterbatch was obtained in the same manner as in Example 1 except that the amount of silica used was changed to 30 parts by mass.

[0110] (Production of foam) ​90 parts by mass of LDPE, 10 parts by mass of a zirconium oxide-containing masterbatch, 1 part of a foaming nucleating agent. A resin composition containing 75 parts by mass and 3.0 parts by mass of an anti-shrinkage agent was charged into an extruder, and this extrusion After injecting 7.7 parts by mass of isobutane gas from the middle of the machine, it was cooled to the appropriate foaming temperature, and the tip It was extruded from a ring-shaped die attached to obtain a foam. The obtained foam had a width of 93 m m, a cylindrical shape with a thickness of 1.49 mm, a basis weight of 15.0 g / m, a foaming ratio of 17.7 times, a continuous bubble rate of 3.3%, a cell size of 1.20 mm, and an average skin layer thickness of 0.019 mm.

[0111] Example 5 Instead of 90 parts by mass of LDPE and 10 parts by mass of the zirconium oxide-containing masterbatch , 80 parts by mass of LDPE and 20 parts by mass of the zirconium oxide-containing masterbatch were used. Otherwise A foam was produced in the same manner as in Example 4. The obtained foam had a width of 62 mm and a thickness of 1 .66 mm in a cylindrical shape, a basis weight of 13.6 g / m, a foaming ratio of 14.7 times, a continuous bubble rate of 9.0 %, a cell size of 1.24 mm, and an average skin layer thickness of 0.017 mm.

[0112] The temperature sensitivity (emissivity of far-infrared rays) of the foams obtained in Comparative Example 1 and Examples 1, 3, and 5 The results of the evaluation are shown in Table 1.

[0113]

Table 1

[0114] As is clear from the results in Table 1, the foams of the examples have a higher emissivity of far-infrared rays than the foam of Comparative Example 1 .

Industrial Applicability

[0115] The foam of the present invention can be used in various applications that require temperature sensitivity and cushioning properties, such as daily necessities (such as tatami mats, kitchen mats, cushions, etc.), outdoor supplies (such as tents, outdoor mats, etc.), disaster prevention goods (such as capsule tents, cold-proof jackets, etc.), pet supplies (such as cages, bath mats, etc.), bedding and bedding supplies (such as futons, mattress pads, etc.). tatami mats, kitchen mats, cushions, etc.), outdoor supplies (such as tents, outdoor mats etc.), disaster prevention goods (such as capsule tents, cold-proof jackets, etc.), pet supplies (such as cages, bath mats, etc.), bedding and bedding supplies (such as futons, mattress pads, etc.).

Claims

1. A foam comprising a resin component composed of a thermoplastic resin and / or its crosslinked product and zirconium oxide, wherein the thermoplastic resin contains an olefin resin, the proportion of the zirconium oxide is 0.01 to 8 parts by mass with respect to 100 parts by mass of the resin component, the zirconium oxide is dispersed as a dispersed phase in the resin component, the average diameter of the dispersed phase is 10 μm or less, and the expansion ratio is 10 times or more.

2. The foam according to Claim 1, wherein the average diameter of the dispersed phase is less than 100 nm.

3. The foam according to Claim 1 or 2, wherein the resin component is a polyethylene resin.

4. The foam according to any one of Claims 1 to 3, further comprising silica gel.

5. The foam according to any one of Claims 1 to 4, wherein the zirconium oxide is localized near the wall surface of the void and / or the skin layer.

6. The foam according to any one of Claims 1 to 5, which is a heat-sensitive foam capable of releasing heat.

7. A method for producing a foam according to any one of Claims 1 to 6, comprising foam-molding a foamable resin composition containing a raw material resin component and zirconium oxide.

8. The production method according to Claim 7, wherein the foamable resin composition has a dispersed phase in which the zirconium oxide is dispersed in the raw material resin component as a matrix, and the average diameter of the dispersed phase is 100 nm or less.

9. The production method according to Claim 8, wherein the foamable resin composition is a combination of a masterbatch in which zirconium oxide is dispersed in a first raw material resin component as a matrix in molecular or atomic units as a dispersed phase and a second raw material resin component.

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