Resin foam and method for manufacturing resin foam

Abstract

To improve impact resilience of a resin foam while ensuring its flexibility.SOLUTION: A resin foam comprises a resin, and a titanate compound fiber of more than 0 pt.mass and less than 19 pts.mass relative to 100 pts.mass of the resin.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to a resin foam and a method for producing a resin foam. [Background technology]

[0002] Patent Document 1 discloses a foam decorative sheet having a foaming agent-containing resin layer obtained by blending 19 parts by mass of titanic acid compound fiber with 100 parts by mass of resin. Patent Document 2 discloses a cross-linked polyethylene foam obtained by blending 50 parts by mass of titanic acid compound fiber with 100 parts by mass of resin. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-073209 [Patent Document 2] Japanese Patent Application Laid-Open No. 2002-161161 Summary of the Invention [Problem to be solved by the invention]

[0004] However, conventional resin foams have a risk of increasing density and decreasing resilience depending on the amount of titanate compound fiber added. Furthermore, when resin foams of the same density are compared, resin foams with higher resilience tend to be harder.

[0005] The present disclosure aims to improve the impact resilience of a resin foam while ensuring its flexibility. The present disclosure can be realized as the following aspects. [Means for solving the problem]

[0006] Resin and The resin foam contains titanate compound fibers in an amount of more than 0 parts by mass and less than 19 parts by mass per 100 parts by mass of the resin. [Effects of the Invention]

[0007] According to the present disclosure, it is possible to improve the impact resilience while ensuring flexibility. DETAILED DESCRIPTION OF THE INVENTION

[0008] Here, a preferred example of the present disclosure will be described. A resin foam, wherein the resin includes a polyolefin resin. A resin foam, wherein the resin includes an ethylene-vinyl acetate copolymer. A resin foam, wherein the resin includes a polyester-based thermoplastic elastomer. The titanate compound fibers have an average fiber length of 5 μm or more and 30 μm or less, The resin foam, wherein the fiber diameter of the titanic acid compound fibers is 0.2 μm or more and 1.0 μm or less.

[0009] Resin and titanic acid compound fibers in an amount of more than 0 parts by mass and less than 19 parts by mass relative to 100 parts by mass of the resin; A foaming agent; A resin foam obtained by foaming a composition containing a crosslinking agent.

[0010] Resin and titanic acid compound fibers in an amount of more than 0 parts by mass and less than 19 parts by mass per 100 parts by mass of the resin; A foaming agent; A method for producing a resin foam, comprising foaming a composition containing a crosslinking agent.

[0011] The present disclosure will be described in detail below. In this specification, when a numerical range is indicated using "-", it is intended to include both the lower limit and the upper limit unless otherwise specified. For example, the expression "10-20" includes both the lower limit "10" and the upper limit "20". In other words, "10-20" has the same meaning as "10 or more and 20 or less".

[0012] 1.Resin foam The resin foam of the present embodiment contains a resin and titanate compound fibers in an amount of more than 0 parts by mass and less than 19 parts by mass per 100 parts by mass of the resin.

[0013] (1) Resin The resin is not particularly limited. The resin preferably contains a polyolefin-based resin. That is, the resin foam may be a polyolefin-based resin foam. Generally, when an inorganic filler is blended into a polyolefin-based resin foam, the density tends to increase and the resilience modulus tends to decrease. The technology of the present disclosure is particularly effective for polyolefin-based resin foams from the viewpoint of increasing the resilience modulus while suppressing an increase in density. The content of the polyolefin resin is not particularly limited, and is preferably 40 parts by mass or more and 100 parts by mass or less, more preferably 50 parts by mass or more and 90 parts by mass or less, and even more preferably 60 parts by mass or more and 85 parts by mass or less, relative to 100 parts by mass of the total resin.

[0014] From the viewpoint of improving the impact resilience, the resin more preferably contains a polyolefin resin and a polyester thermoplastic elastomer. The contents of the polyolefin resin and the polyester thermoplastic elastomer are not particularly limited. The content of the polyolefin resin can be as described above. The content of the polyester thermoplastic elastomer is preferably 0 parts by mass or more and 60 parts by mass or less, more preferably 10 parts by mass or more and 50 parts by mass or less, and even more preferably 15 parts by mass or more and 40 parts by mass or less, when the total amount of the resins is 100 parts by mass.

[0015] (1.1) Polyolefin resin Examples of polyolefin resins include polyethylene resins, polypropylene resins, polyolefin elastomers, etc. The polyolefin resins may be one type or a blend of two or more types.

[0016] Examples of polyethylene-based resins include ethylene-vinyl acetate copolymer (EVA), high-density polyethylene (HDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), ethylene-ethyl acrylate copolymer (EEA), and ethylene-butyl acrylate copolymer (EBA). Polyethylene-based resins may also be copolymers of ethylene monomers with other copolymerizable monomers, such as ethylene-α-olefin copolymers. Examples of α-olefins include propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-hexadecene, 1-octadecene, 1-nonadecene, 1-eicosene, and 4-methyl-1-pentene. The polyethylene resin preferably has an MFR (melt flow rate, JIS K7210, 190° C., load 2.16 kg) in the range of 1 g / 10 min to 15 g / 10 min.

[0017] Among polyethylene-based resins, ethylene-vinyl acetate copolymer (EVA) is preferably used. The vinyl acetate content in EVA is not particularly limited. From the viewpoint of ensuring flexibility, the vinyl acetate content is preferably 5% by mass or more, and more preferably 10% by mass or more, where the mass of EVA is 100% by mass. On the other hand, the vinyl acetate content is preferably 40% by mass or less, and more preferably 30% by mass or less. Vinyl acetate is more easily crosslinked than ethylene. If the vinyl acetate content is equal to or less than the above value, the degree of crosslinking of the resin foam can be prevented from becoming excessively high. From these viewpoints, the vinyl acetate content is preferably 5% by mass or more and 40% by mass or less, and more preferably 10% by mass or more and 30% by mass or less. The vinyl acetate content is based on JIS K 6924-1. EVA has a density (ASTM D1505) of 0.92 g / cm 3 -0.97g / cm 3 and a MFR (ASTM D1238, 190°C, load 2.16 kg) in the range of 1g / 10min to 10g / 10min is preferably used.

[0018] Examples of polypropylene resins include homopolypropylene, ethylene-propylene random copolymers, and ethylene-propylene block copolymers. The polypropylene resin preferably has an MFR (JIS K7210, 230°C, load 2.16 kg) in the range of 0.5 g / 10 min to 7 g / 10 min.

[0019] Examples of polyolefin elastomers include polyolefin thermoplastic elastomers (TPO), polybutadiene thermoplastic elastomers, hydrogenated styrene butadiene rubber (HSBR), styrene-ethylenebutylene-olefin crystalline block polymers (SEBC), olefin crystalline-ethylenebutylene-olefin crystalline block polymers (CEBC), styrene-ethylenebutylene-styrene block polymers (SEBS), olefin block copolymers (OBC), and graft copolymers such as polyolefin-vinyl graft copolymers. The polyolefin elastomer preferably has an MFR (JIS K7210, 230°C, load 2.16 kg) in the range of 1 g / 10 min to 15 g / 10 min.

[0020] (1.2) Polyester-based thermoplastic elastomer Thermoplastic polyester elastomers (TPEEs) are copolymers of, for example, hard segments containing polyester units and soft segments containing polyether or polyester units. The types and composition ratios of the hard and soft segments are not particularly limited. Examples of hard segments include crystalline polyesters such as polybutylene terephthalate, polybutylene naphthalate, and polyethylene terephthalate. Examples of soft segments include polyoxyalkylene glycols such as polytetramethylene glycol, and polyesters such as polycaprolactone and polybutylene adipate. Commercially available polyester thermoplastic elastomers include "Arnitel" (registered trademark) manufactured by DSM Engineering Materials, "Pelprene" (registered trademark) manufactured by Toyobo Co., Ltd., "Hytrel" (registered trademark) manufactured by DuPont-Toray Co., Ltd., and "Flexmar" (registered trademark) manufactured by Nippon Synthetic Chemical Industry Co., Ltd. Among these, "Arnitel ECO" manufactured by DSM Engineering Materials, which contains plant-derived components, is preferred from the viewpoint of environmental impact. TPEE has an MVR (Melt Volume Rate, ISO1133, 230℃, load 2.16kg) of 20cm 3 / 10min-60cm 3 A range of 1 / 10 min is preferably used.

[0021] (2) Titanic acid compound fiber The titanate compound is preferably a titanate metal salt compound, such as potassium titanate, barium titanate, strontium titanate, calcium titanate, magnesium titanate, lead titanate, aluminum titanate, lithium titanate, and sodium titanate. Among the titanate compounds listed above, potassium titanate, represented by the chemical formula K2O·nTiO2 (n is an integer between 1 and 10), is preferred. The potassium titanate is more preferably potassium octatitanate, represented by the chemical formula K2O·8TiO2. The titanate compound may be one type, or two or more types may be mixed together.

[0022] The size of the titanate compound fiber is not particularly limited. The average fiber length of the titanate compound fiber is preferably 1 μm or more and 100 μm or less, more preferably 3 μm or more and 50 μm or less, and even more preferably 5 μm or more and 30 μm or less. The fiber diameter of the titanate compound fiber is preferably 0.05 μm or more and 10.0 μm or less, more preferably 0.1 μm or more and 5.0 μm or less, and even more preferably 0.2 μm or more and 1.0 μm or less. The average fiber length of the titanate compound fiber can be determined by observing the fiber with an electron microscope and analyzing the electron microscope image by the Luzex method. The fiber diameter of the titanate compound fiber can be measured by a microscopic method.

[0023] The content of the titanate compound fiber is greater than 0 parts by mass, preferably 2 parts by mass or more, more preferably 4 parts by mass or more, and even more preferably 5 parts by mass or more, per 100 parts by weight of resin, from the viewpoint of improving impact resilience. The content of the titanate compound fiber is less than 19 parts by mass, preferably 17 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 13 parts by mass or less, from the viewpoint of suppressing an increase in density. From these viewpoints, the content of the titanate compound fiber is greater than 0 parts by mass and less than 19 parts by mass, preferably 2 parts by mass or more and 17 parts by mass or less, more preferably 4 parts by mass or more and 15 parts by mass or less, and even more preferably 5 parts by mass or more and 13 parts by mass or less.

[0024] (3) Other ingredients The resin foam can be obtained by foaming a composition containing a resin, the titanate compound fiber in the above amount, a foaming agent, and a crosslinking agent. The composition may optionally contain a foaming agent, a crosslinking agent, a filler (e.g., calcium carbonate), an antioxidant, a foaming aid, a crosslinking aid, a pigment, a plasticizer, a function-imparting agent (e.g., a flame retardant), and the like. The composition may also contain polymers other than the above-described resins, such as modifiers, to the extent that the effects of the present disclosure are not significantly impaired.

[0025] The foaming agent is preferably a thermal decomposition type that decomposes upon heating to generate gas, and is not particularly limited. For example, one or more of azodicarbonamide (ADCA), 2,2'-azobisisobutyronitrile, diazoaminobenzene, benzenesulfonylhydrazide, benzene-1,3-sulfonylhydrazide, diphenyloxide-4,4'-disulfonylhydrazide, 4,4'-oxybisbenzenesulfonylhydrazide, paratoluenesulfonylhydrazide, N,N'-dinitrosopentamethylenetetramine, N,N'-dinitroso-N,N'-dimethylphthalamide, terephthalazide, pt-butylbenzazide, sodium bicarbonate, ammonium bicarbonate, etc. are used. Azodicarbonamide and 4,4'-oxybisbenzenesulfonylhydrazide are particularly preferred. The content of the foaming agent can be 1 to 20 parts by mass per 100 parts by weight of the resin.

[0026] When azodicarbonamide is used as the foaming agent, zinc oxide, adipic acid dihydrazide, lead sulfate, urea, zinc stearate, etc. may be used as a foaming assistant. The content of the foaming assistant can be 0.3 parts by mass or more and 10 parts by mass or less per 100 parts by mass of the resin.

[0027] The crosslinking agent is preferably used for chemical crosslinking. Examples of the crosslinking agent include organic peroxides such as dicumyl peroxide, 2,5-dimethyl-2,5-bis-tertiarybutylperoxyhexane, and 1,3-bis-tertiaryperoxy-isopropylbenzene. The content of the crosslinking agent can be 0.3 parts by mass or more and 2 parts by mass or less per 100 parts by mass of the resin.

[0028] 2. Properties and uses of resin foam (1) Apparent density The apparent density measured in accordance with JIS K 6767-1999 is 10 kg / m 3 More than 100kg / m 3 Less than 20 kg / m is preferable. 3 More than 80kg / m 3The following is more preferable. The expansion ratio of the resin foam is, for example, 5 to 50 times. The expansion ratio of the resin foam increases as the density of the resin foam decreases. The expansion ratio of the resin foam can be calculated based on the apparent density of the resin foam.

[0029] (2) Tensile strength The tensile strength measured in accordance with JIS K 6767-1999 at a tension speed of 500 mm / min is preferably 400 kPa or more and 800 kPa or less, and more preferably 500 kPa or more and 700 kPa or less.

[0030] (3) Compressive stress The compressive stress at 25% compression measured in accordance with JIS K 6767-1999 is preferably 10 kPa or more and 40 kPa or less, and more preferably 15 kPa or more and 30 kPa or less. The compressive stress at 50% compression measured in accordance with JIS K 6767-1999 is preferably 40 kPa or more and 75 kPa or less, more preferably 45 kPa or more and 65 kPa or less.

[0031] (4) Rebound elasticity The rebound resilience measured in accordance with DIN 53573 shape B is preferably 40% or more, more preferably 50% or more, 60% or more, or 65% or more, and may be 70% or more. The upper limit of the rebound resilience is 100%, and it may be 90% or less.

[0032] (5)Applications The resin foam of the present embodiment has the properties of being lightweight and having a high impact resilience, and is suitable for a variety of applications, such as shoe sole materials (insoles), sporting goods, buoyancy materials, heat insulating materials, joint materials, waterproofing materials, and cushioning materials.

[0033] 3. Manufacturing method of resin foam The resin foam can be produced by, for example, foaming a composition containing a resin, the titanate compound fiber in the above amount, a foaming agent, and a crosslinking agent. Specifically, the resin foam can be produced by mixing the composition, injecting the mixture into a foaming mold, and heating it to foam.

[0034] The foaming method for the composition can be either a one-stage foaming method or a two-stage foaming method. The one-stage foaming method is a method in which raw materials for a polyolefin resin foam are filled into a foaming mold, heated and pressurized to decompose the foaming agent and crosslinking agent, and then the pressure is released, thereby expanding the foam to the desired apparent density in one go. The two-stage foaming method is a method in which an intermediate foam obtained by the one-stage foaming method is heated at normal pressure and foamed in two stages to obtain a final foam with the desired apparent density. The foaming method to be used can be determined appropriately depending on the expansion ratio, foam quality, application, etc.

[0035] The resin foam can be obtained as a crosslinked resin foam by crosslinking the composition. The composition may be crosslinked by chemical crosslinking using the above-mentioned organic peroxide, silane crosslinking, electron beam crosslinking, or the like.

[0036] 4. Effects of this embodiment In order to improve the rebound resilience of resin foams, the addition of fillers as reinforcing materials has been considered. However, when magnesium sulfate fibers are blended into resin foams, the compressive stress increases, but the density of the resin foam also increases, making it impossible to sufficiently increase the rebound resilience. In other words, when magnesium sulfate fibers are blended into resin foams, it is not possible to improve the rebound resilience while maintaining the flexibility of the resin foam. On the other hand, the resin foam of this embodiment can improve the rebound resilience while suppressing an increase in compressive stress and maintaining flexibility.

[0037] The reason why the resin foam of the present embodiment can improve impact resilience while maintaining flexibility is presumed to be as follows: However, the present disclosure should not be construed as being limited by this presumed reason. When a resin foam contains more than 0 parts by mass but less than 19 parts by mass of titanate compound fiber, the titanate compound fiber is believed to act as a foam nucleating agent. Specifically, during the process of decomposition of the chemical foaming agent to form the foam structure, the titanate compound fiber is believed to act as a foam initiation point, increasing the number of cells and reducing the size of the cells. As a result, the increase in density due to the addition of titanate compound fiber is suppressed, resulting in a higher rebound resilience. Furthermore, titanate compound fiber has higher tensile strength, tensile modulus, Mohs hardness, and other properties than magnesium sulfate fiber. In the resin foam of this embodiment, the titanate compound fiber is believed to be uniformly dispersed within the cell walls of the resin foam, supporting the resin skeleton and thereby contributing to improved rebound resilience. [Example]

[0038] The present invention will be explained in more detail below with reference to examples.

[0039] 1. Preparation of Resin Foam Resin foams of Examples and Comparative Examples were produced according to the blending ratios shown in Table 1. In Table 1, the details of the main raw materials are shown below. Polyolefin resin: Ethylene-vinyl acetate copolymer (EVA) ASIA Polymer Corporation, EV103 MFR (190℃, 2.16kg, ASTM D 1238): 1.8g / 10min Vinyl acetate content: 21% by mass Density: 0.944g / cm3 (ASTM D 1505) Polyester thermoplastic elastomer (TPEE) DSM Engineering Materials, Arnitel ECO L400 MVR (230℃, 2.16kg, ISO 1133): 45cm 3 / 10min Titanate compound fiber: Potassium titanate fiber, K2O·8TiO2 Otsuka Chemical Co., Ltd., TISMO D Average fiber length 10μm-20μm, fiber diameter 0.3μm-0.6μm Specific gravity 3.5, tensile strength 7GPa, tensile modulus 280GPa, Mohs hardness 4 Magnesium sulfate fiber: MgSO4·5Mg(OH)2·3H2O Mos Heidi, manufactured by Ube Industries Average fiber length 8μm-30μm, fiber diameter 0.5μm-1.0μm Specific gravity 2.3, tensile strength 3.5GPa, tensile modulus 95GPa, Mohs hardness 2.5 Foaming agent: Azodicarbonamide (ADCA) Foaming agent: 2 types of zinc oxide Crosslinking agent: dicumyl peroxide

[0040] [Table 1]

[0041] 2. Evaluation Method (1) Apparent density Apparent density (kg / m 3 ) was measured in accordance with JIS K 6767-1999. The expansion ratio of the resin foam was calculated based on the apparent density of the resin foam. (2) Tensile strength The tensile strength (kPa) was measured in accordance with JIS K 6767-1999. Samples were punched out in the shape specified in ISO1798 and had a thickness of 10 mm. (3) Compressive stress The 25% compressive stress (kPa) was measured at 25% compression in accordance with JIS K 6767-1999. The sample had a thickness of 10 mm, a length of 100 mm, and a width of 100 mm. The 50% compressive stress (kPa) was measured at 50% compression in accordance with JIS K 6767-1999. The sample had a thickness of 10 mm, a length of 100 mm, and a width of 100 mm.

[0042] (4) Rebound elasticity The rebound resilience (%) was measured in accordance with DIN 53573 shape B. The rebound resilience was measured using a Digitest II rebound resilience tester manufactured by Burleis under conditions of an impact force of 0.2 J and an impact speed of 2 m / sec. The sample was 50 mm thick and had a rectangular shape with dimensions of 80 mm x 80 mm.

[0043] [Table 1]

[0044] 3.Results The results are shown in Table 1. Examples 1-4 had the same 25% compressive stress as Comparative Example 1 (blank) which did not contain titanic acid compound fibers. Examples 1-4 had a lower 50% compressive stress than Comparative Example 1 (blank) which did not contain titanic acid compound fibers. Examples 1-4 had a higher rebound resilience than Comparative Example 1 (blank) which did not contain titanic acid compound fibers.

[0045] Examples 1-4 had lower 25% compressive stress and 50% compressive stress than Comparative Examples 2 and 3, which contained magnesium sulfate fibers. Examples 1-4 had higher rebound resilience than Comparative Examples 2 and 3, which contained magnesium sulfate fibers.

[0046] 4. Effects of the Example According to the above-described embodiments, the flexibility of the resin foam can be ensured while improving the impact resilience.

[0047] The present disclosure is not limited to the above-described embodiments, and various modifications and variations are possible.

Claims

1. Resin and and titanic acid compound fibers in an amount of more than 0 parts by mass and less than 19 parts by mass per 100 parts by mass of the resin, the resin includes an ethylene-vinyl acetate copolymer; Apparent density is 10 kg / m ３ 50.5kg / m or more ３ The following is a resin foam.

2. Resin and and titanic acid compound fibers in an amount of more than 0 parts by mass and less than 19 parts by mass per 100 parts by mass of the resin, The resin includes a polyester-based thermoplastic elastomer, Apparent density is 10 kg / m ３ 50.5kg / m or more ３ The following is a resin foam.

3. Resin and titanic acid compound fibers in an amount of more than 0 parts by mass and less than 19 parts by mass relative to 100 parts by mass of the resin; A foaming agent; A resin foam obtained by foaming a composition containing a crosslinking agent, Apparent density is 10 kg / m ３ 50.5kg / m or more ３ The following is a resin foam.

4. Resin and titanic acid compound fibers in an amount of more than 0 parts by mass and less than 19 parts by mass per 100 parts by mass of the resin; A foaming agent; A method for producing a resin foam, comprising foaming a composition containing a crosslinking agent, The apparent density of the resin foam is 10 kg / m ３ 50.5kg / m or more ３ The following is a method for producing a resin foam.

5. Resin and and titanic acid compound fibers in an amount of more than 0 parts by mass and less than 19 parts by mass per 100 parts by mass of the resin, The resin includes an ethylene-vinyl acetate copolymer and a polyester-based thermoplastic elastomer, a resin foam in which, when the total amount of the resins is 100 parts by mass, the content of the ethylene-vinyl acetate copolymer is 60 parts by mass or more and 85 parts by mass or less, and the content of the polyester-based thermoplastic elastomer is 15 parts by mass or more and 40 parts by mass or less.

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