Polyurethane foam and sheet material including said polyurethane foam

Abstract

[Problem] To provide polyurethane foam having excellent impact-absorbing properties in both a room-temperature range and a low-temperature range. [Solution] The present invention provides polyurethane foam having a loss tangent satisfying tanδ≥0.2 throughout the temperature range of 10-20°C. This polyurethane foam can have a density of 100 kg / m3 or higher. This polyurethan foam may have a difference between the maximum of tanδ in the temperature range of -20 to 40°C and the tanδ at -20°C of 0.40 or less. Also provided is a sheet material including this polyurethane foam.

Description

Polyurethane foam and sheet material comprising said polyurethane foam

[0001] The present technology relates to a foldable polyurethane foam that has good impact absorption properties at low and normal temperatures, and a sheet material including the polyurethane foam.

[0002] Polyurethane foams are widely used in a variety of fields, including furniture such as sofas and chairs, bedding such as mattresses and pillows, clothing such as underwear, daily necessities such as dishwashing and cleaning sponges, interior products for vehicles and aircraft such as car seats, electronic devices such as mobile phones, cameras, and televisions, electrical appliances such as home appliances, toys, and miscellaneous goods. Various developments are underway to improve quality and add new functions according to each field and purpose.

[0003] For example, Patent Document 1 proposes a low-resilience urethane foam obtained by reacting a urethane foam composition containing a polyol (a), a polyisocyanate (b), a catalyst (c), and a blowing agent (d), the low-resilience urethane foam having at least one glass transition point in the temperature range of -70°C to -20°C and one in the temperature range of 0°C to 60°C, and characterized in that, when the glass transition point is expressed as the peak value of tan δ obtained when dynamic viscoelasticity is measured at a frequency of 10 Hz, the peak value of tan δ in the temperature range of -70°C to -20°C is 0.15 or more, and the peak value of tan δ in the temperature range of 0°C to 60°C is 0.3 or more. This low-resilience urethane foam has excellent low resilience at room temperature and little increase in hardness even at low temperatures.

[0004] Furthermore, for example, Patent Document 2 proposes a technology for producing polyurethane foam that can solve the problem of temperature sensitivity of the foam while still maintaining high air flow, low compression set, and good tear strength, by reacting (1) toluene diisocyanate with (2) a polyol mixture containing a specific polyol as an isocyanate-reactive component in the presence of (3) one or more blowing agents, (4) one or more catalysts, and (5) one or more surfactants.

[0005] JP-A-11-286566 Publication Special Publication No. 2020-510127

[0006] Even if a polyurethane foam has flexibility in the normal temperature range (e.g., 1 to 30°C), the foam may become harder at low temperatures (e.g., below 0°C), losing flexibility and making the feel worse. In this case, there is a problem that the foam is difficult to use in applications requiring impact absorption performance at low temperatures (e.g., below 0°C).

[0007] Therefore, the main object of the present technology is to provide a polyurethane foam that has excellent impact absorption properties both in the normal temperature range and in the low temperature range.

[0008] Conventionally, polyurethane foams formulated to undergo glass transition at room temperature exhibit excellent low resilience at room temperature due to this glass transition phenomenon. However, at temperatures before this glass transition occurs, such as temperatures below 0°C, polyurethane foams enter a glassy state, resulting in a significant increase in hardness compared to room temperature (see, for example, Patent Document 1). Based on this knowledge, conventional techniques have ensured impact absorption performance at room and low temperatures by formulating polyurethane foam raw materials to have multiple glass transition points (see, for example, Patent Document 1). In contrast, the present technology has discovered that if the loss tangent tanδ satisfies a predetermined value within a specified temperature range, the impact absorption of the polyurethane foam will be improved at both room and low temperatures.

[0009] That is, the present technology first provides a polyurethane foam that satisfies the loss tangent tanδ≧0.2 over the entire temperature range of 10 to 20°C. The density of the polyurethane foam according to the present technology is 100 kg / m ３or more. The polyurethane foam according to the present technology may have only one glass transition point in the temperature range of -20 to 40°C. The polyurethane foam according to the present technology may have a difference of 0.40 or less between the maximum tan δ in the temperature range of -20 to 40°C and the tan δ at -20°C. The polyurethane foam according to the present technology may have an elongation of 150% or more. The polyurethane foam according to the present technology may have a glass transition point of 10°C or less. The polyurethane foam according to the present technology may have a glass transition point of 15°C or more.

[0010] The present technology next provides a sheet material comprising the polyurethane foam according to the present technology. The thickness of the sheet material according to the present technology can be set to 20 mm or less.

[0011] In this technology, "low temperature" refers to a temperature below 0°C. In this technology, "normal temperature" refers to a temperature of approximately 5 to 35°C, but can reach 35°C or higher in warm or tropical regions or in seasons such as summer.

[0012] FIG. 1 is a diagram showing the formulations and physical property values ​​of examples and comparative examples of the present technology. FIG. 2 is a graph showing the relationship between loss tangent tanδ and temperature in examples 1 to 5 of the present technology and comparative example 1. FIG. 3 is a schematic diagram showing the shape of test specimens used to measure tensile strength and elongation. FIG. 4 is a schematic diagram showing the shape of test specimens used to measure tear strength. FIG. 5 is a conceptual diagram showing a method for impact absorption testing. FIG. 6 is a graph showing the relationship between loss tangent tanδ and temperature in examples 6 to 10 of the present technology.

[0013] Preferred embodiments for implementing the present technology will be described below. The embodiments described below are examples of typical embodiments of the present technology, and any of the embodiments can be combined. Furthermore, the scope of the present technology is not to be interpreted narrowly by these embodiments.

[0014] 1. Polyurethane Foam The polyurethane foam according to the present technology is characterized by having good impact absorption properties at both low and normal temperatures. More specifically, the impact absorption properties at both -20°C and 22°C are 20 kN or less. Note that, in the present technology, the impact absorption properties are values ​​measured by the method described in the examples below. The physical properties of the polyurethane foam according to the present technology are described in detail below.

[0015] (1) Loss tangent tanδ The polyurethane foam according to the present technology satisfies loss tangent tanδ≧0.2 over the entire temperature range of 10°C to 20°C. The lower limit of the temperature range satisfying loss tangent tanδ≧0.2 is 10°C or higher, so that the functions and effects of the present technology can be exhibited. However, it is preferably 6°C or higher, more preferably 5°C or higher, and even more preferably 4°C or higher. By lowering the lower limit of the temperature range satisfying loss tangent tanδ≧0.2, it is possible to further improve impact absorption in low temperature ranges. As a result, the polyurethane foam can be suitably used in applications in low-temperature environments.

[0016] The upper limit of the temperature range satisfying loss tangent tanδ ≧ 0.2 can exhibit the functions and effects of the present technology if it is 20° C. or lower, but is preferably 30° C. or lower, more preferably 40° C. or lower, and even more preferably 45° C. or lower. By setting the upper limit of the temperature range satisfying loss tangent tanδ ≧ 0.2 to a higher temperature, it is possible to improve the impact absorption properties at room temperature or higher.

[0017] In the polyurethane foam according to the present technology, the difference between the maximum tan δ in the temperature range of -20 to 40°C and the tan δ at -20°C is preferably 0.40 or less. By ensuring that the difference is 0.40 or less, the impact absorption properties in the low temperature range can be further improved. As a result, the foam can be suitably used in applications under low temperature environments.

[0018] Furthermore, in the polyurethane foam according to the present technology, the difference between the maximum value of tan δ in the temperature range of -20 to 40°C and the tan δ at 0°C is preferably 0.30 or less, and smaller than the difference between the maximum value of tan δ in the temperature range of -20 to 40°C and the tan δ at -20°C. That is, in a graph with loss tangent tan δ on the vertical axis and temperature on the horizontal axis, it is preferable that tan δ slopes gently from the maximum value in the temperature range of -20 to 40°C toward the -20°C side.

[0019] (2) Density The density of the polyurethane foam according to the present technology can be freely set as long as it does not impair the function and effect of the present technology. The density of the polyurethane foam according to the present technology is, for example, 90 kg / m ３ More than 100 kg / m ３ More preferably, 120 kg / m ３ More preferably, 150 kg / m ３ More preferably, 180 kg / m ３ More preferably, 200 kg / m ３ By setting the density of the polyurethane foam according to the present technology within this range, the foam can be suitably used for insoles, shock absorbing materials, armrests, headrests, footrests, shoulder pads for bags and the like, cushioning materials for everyday items, protectors for sports, and the like.

[0020] The upper limit of the density of the polyurethane foam according to the present technology can be freely set as long as it does not impair the purpose and effect of the present technology. For example, ３ Preferably 900 kg / m or less ３ or less, more preferably 800 kg / m ３ More preferably, 700 kg / m or less ３ By setting the density of the polyurethane foam within this range, it is possible to impart cushioning properties without impairing the flexibility of the polyurethane foam (preventing it from becoming hard).

[0021] In the present technology, the density is a value measured by a method conforming to JIS K6401:2011.

[0022] (3) Glass Transition Point The glass transition point of the polyurethane foam according to the present technology can be freely set as long as it does not impair the functions and effects of the present technology. The lower limit of the glass transition point of the polyurethane foam according to the present technology is, for example, −20°C or higher, preferably −15°C or higher, more preferably −10°C or higher, and even more preferably −6°C or higher. The upper limit of the glass transition point of the polyurethane foam according to the present technology is, for example, 40°C or lower, preferably 35°C or lower. Thus, the polyurethane foam according to the present technology is characterized by having good impact absorption properties at low and normal temperatures, regardless of whether the glass transition point of the polyurethane foam according to the present technology is in a low to high temperature range.

[0023] Furthermore, the number of glass transition points of the polyurethane foam according to the present technology can be freely set as long as it does not impair the functions and effects of the present technology. Conventionally, it has been considered preferable to have multiple glass transition points in order to improve impact absorption at both low and normal temperatures. However, the present technology has succeeded in improving impact absorption at both low and normal temperatures regardless of the number of glass transition points. That is, the number of glass transition points of the polyurethane foam according to the present technology may be one or two or more.

[0024] In the present technology, the glass transition temperature is a value measured by the method described in the examples below.

[0025] (4) Elongation The elongation of the polyurethane foam according to the present technology can be freely set as long as it does not impair the function and effect of the present technology. The lower limit of the elongation of the polyurethane foam according to the present technology is, for example, 120% or more, preferably 150% or more, more preferably 160% or more, and even more preferably 170% or more. By setting the lower limit of the elongation within this range, bending cracking of the polyurethane foam at low temperatures can be prevented. The upper limit of the elongation of the polyurethane foam according to the present technology is not particularly limited, and is, for example, 800% or less, 700% or less, or 600% or less.

[0026] In the present technology, the elongation percentage is a value measured by a method conforming to JIS K6251:2010.

[0027] (5) Tensile Strength The tensile strength of the polyurethane foam according to the present technology can be freely set as long as it does not impair the function and effect of the present technology. The lower limit of the tensile strength of the polyurethane foam according to the present technology is, for example, 0.5 MPa or more, preferably 0.6 MPa or more, and more preferably 0.7 MPa or more. When the lower limit of the tensile strength of the polyurethane foam is within this range, it can be used in applications requiring strength. The upper limit of the tensile strength of the polyurethane foam according to the present technology is not particularly limited, and is, for example, 3.0 MPa or less, 2.5 MPa or less, or 2.0 MPa or less.

[0028] In the present technology, the tensile strength is a value measured by a method conforming to JIS K6251:2010.

[0029] (6) Tear Strength The tear strength of the polyurethane foam according to the present technology can be freely set as long as it does not impair the function and effect of the present technology. The lower limit of the tear strength of the polyurethane foam according to the present technology is, for example, 1.8 N / mm or more, preferably 2.0 N / mm or more, more preferably 2.2 N / mm or more, and even more preferably 2.4 N / mm or more. When the lower limit of the tear strength of the polyurethane foam is within this range, it can be used in applications requiring strength. The upper limit of the tear strength of the polyurethane foam according to the present technology is not particularly limited, and is, for example, 8.0 N / mm or less, 7.5 N / mm or less, or 7.0 N / mm or less.

[0030] In the present technology, the tear strength is a value measured by a method conforming to JIS K6252:2007.

[0031] (7) Compression Set The compression set of the polyurethane foam according to the present technology can be freely set as long as it does not impair the function and effect of the present technology. The upper limit of the compression set of the polyurethane foam according to the present technology is, for example, 10% or less, preferably 8.0% or less, and more preferably 7.5% or less. By setting the upper limit of the compression set of the polyurethane foam within this range, it is possible to prevent the polyurethane foam from becoming sagging and improve its cushioning performance. The lower limit of the compression set of the polyurethane foam according to the present technology is not particularly limited and may be 0%.

[0032] In the present technology, the tensile strength is a value measured by a method conforming to JIS K6401:2011.

[0033] (8) Specific Embodiments The polyurethane foam according to the present technology can be broadly classified into at least the following two embodiments. Specific embodiments will be described.

[0034] [First embodiment] A polyurethane foam having an impact absorption of 20 kN or less at both -20°C and 22°C. A polyurethane foam that satisfies tan δ ≧ 0.2 over the entire temperature range of 10 to 20°C is preferred, and a polyurethane foam that satisfies tan δ ≧ 0.2 over the entire temperature range of 0 to 20°C is more preferred. Tan δ is the loss factor, and refers to the ratio of the loss modulus G" to the storage modulus G'. The temperature range is preferably -5°C or higher, more preferably -10°C or higher. The temperature range is preferably 25°C or lower, more preferably 30°C or lower, even more preferably 40°C or lower, and particularly preferably 45°C or lower. The glass transition temperature of the polyurethane foam is preferably within the range of -15 to 30°C, more preferably -15 to 20°C, even more preferably -10 to 15°C, and particularly preferably -10 to 10°C. As a raw material, an ester polyol having a molecular weight of 300 to 1200 is preferably used. As a raw material, a polymer polyol is preferably used. As a filler, an inorganic compound is preferably used. The polyurethane foam of the present disclosure has excellent impact absorption properties at low temperatures and can be used as a protector in cold regions or for winter sports.

[0035] Furthermore, the polyurethane foam according to the first embodiment preferably satisfies loss tangent tanδ≧0.25 in a temperature range of 5° C. to 20° C. In the first embodiment, the lower limit of the temperature range in which loss tangent tanδ≧0.25 is more preferably 0° C. or higher, even more preferably −5° C. or higher, and even more preferably −10° C. or higher. In the first embodiment, the upper limit of the temperature range in which loss tangent tanδ≧0.25 is more preferably 25° C. or lower, even more preferably 30° C. or lower, and even more preferably 35° C. or lower.

[0036] The upper limit of the glass transition point of the polyurethane foam according to the first embodiment is preferably 20° C. or lower, more preferably 15° C. or lower, and even more preferably 10° C. or lower. The lower limit of the glass transition point of the polyurethane foam according to the first embodiment is preferably −15° C. or higher, more preferably −10° C. or higher, even more preferably −8° C. or higher, still more preferably −7° C. or higher, and particularly preferably −6° C. or higher.

[0037] [Second embodiment] Similar to the first embodiment, a polyurethane foam according to a second embodiment is a polyurethane foam having an impact absorption of 20 kN or less at both -20°C and 22°C.

[0038] The polyurethane foam according to the second embodiment preferably satisfies loss tangent tanδ≧0.15 in the temperature range of 0° C. to 20° C. In the second embodiment, the lower limit of the temperature range in which loss tangent tanδ≧0.15 is preferably −2° C. or higher, more preferably −3° C. or higher, and even more preferably −4° C. or higher. In the second embodiment, the upper limit of the temperature range in which loss tangent tanδ≧0.15 is preferably 30° C. or lower, more preferably 40° C. or lower, and even more preferably 45° C. or lower.

[0039] The polyurethane foam according to the second embodiment preferably satisfies loss tangent tanδ≧0.10 in a temperature range of −5° C. to 20° C. In the second embodiment, the lower limit of the temperature range in which loss tangent tanδ≧0.10 is preferably −10° C. or higher, more preferably −12° C. or higher, and even more preferably −15° C. or higher. In the second embodiment, the upper limit of the temperature range in which loss tangent tanδ≧0.10 is preferably 30° C. or lower, more preferably 40° C. or lower, and even more preferably 50° C. or lower.

[0040] The polyurethane foam according to the second embodiment preferably satisfies loss tangent tanδ≧0.08 in a temperature range of −10° C. to 20° C. In the second embodiment, the lower limit of the temperature range in which loss tangent tanδ≧0.08 is preferably −15° C. or higher, more preferably −18° C. or higher, and even more preferably −20° C. or higher. In the second embodiment, the upper limit of the temperature range in which loss tangent tanδ≧0.08 is preferably 30° C. or lower, more preferably 40° C. or lower, even more preferably 50° C. or lower, and still more preferably 60° C. or lower.

[0041] The lower limit of the glass transition point of the polyurethane foam according to the second embodiment is preferably 15° C. or higher, more preferably 18° C. or higher, even more preferably 20° C. or higher, still more preferably 22° C. or higher, and particularly preferably 24° C. or higher. The upper limit of the glass transition point of the polyurethane foam according to the second embodiment is preferably 45° C. or lower, more preferably 40° C. or lower, and even more preferably 35° C. or lower.

[0042] The polyurethane foam according to the second embodiment preferably has only one glass transition point in the temperature range of -20 to 40°C.

[0043] The polyurethane foam of the second embodiment, like the first embodiment, has good impact absorption properties at both low and normal temperatures, and in addition, because it has a low compression residual set value, it is less likely to sag, thereby further improving cushioning performance.

[0044] 2. Composition for Producing Polyurethane Foam The polyurethane foam according to the present technology can be produced using a composition containing a polyol and an isocyanate. The composition used for producing the polyurethane foam according to the present technology can also contain a foam stabilizer, a catalyst, an antioxidant, a filler, a moisture absorbent, etc., as necessary.

[0045] The polyurethane foam according to the present technology is preferably produced using a mechanical froth method, as described below. That is, the composition used for producing the polyurethane foam according to the present technology can be suitably used as a composition for mechanical froth. Each component will be described in detail below.

[0046] (1) Polyols The polyurethane foam according to the present technology can be freely selected and used from one or more polyols used in general polyurethane foams, depending on the physical properties and applications of the polyurethane foam to be produced. Examples of polyols that can be used in the present technology include polymer polyols, polyester polyols, polyether polyols, polyester ether polyols, and polycarbonate polyols. Biomass-derived polyols and biodegradable polyols can also be used.

[0047] (1-1) Molecular Weight of Polyol The molecular weight of the polyol that can be used in the present technology is not particularly limited, and can be freely set depending on the physical properties and applications of the polyurethane foam to be produced.

[0048] In the present technology, it is preferable to use a polyol having a molecular weight of 2500 or more as the polyol, and it is more preferable to use a polymer polyol having a molecular weight of 2500 or more as the polyol having a molecular weight of 2500 or more.

[0049] When a polyol having a molecular weight of 2500 or more is used, its content is not particularly limited and can be freely set. The lower limit of the content of the polyol having a molecular weight of 2500 or more in 100 parts by mass of the polyol component used in the present technology is, for example, 5 parts by mass or more, preferably 10 parts by mass or more, and more preferably 15 parts by mass or more. In particular, in the polyurethane foam according to the second embodiment described above, the lower limit of the content of the polyol having a molecular weight of 2500 or more in 100 parts by mass of the polyol component used in the present technology is preferably 20 parts by mass or more, more preferably 30 parts by mass or more, even more preferably 40 parts by mass or more, and even more preferably 45 parts by mass or more.

[0050] The upper limit of the content of polyols having a molecular weight of 2500 or more in 100 parts by mass of the polyol component used in the present technology is, for example, 70 parts by mass or less, preferably 65 parts by mass or less, and more preferably 63 parts by mass or less. In particular, in the polyurethane foam according to the first embodiment described above, the upper limit of the content of polyols having a molecular weight of 2500 or more in 100 parts by mass of the polyol component used in the present technology is preferably 50 parts by mass or less, more preferably 45 parts by mass or less, even more preferably 40 parts by mass or less, and still more preferably 35 parts by mass or less.

[0051] In the present technology, it is preferable to use a polyol having a molecular weight of 300 or more and 1200 or less as the polyol, and it is more preferable to use a polyester polyol having a molecular weight of 300 or more and 1200 or less as the polyol having a molecular weight of 300 or more and 1200 or less.

[0052] When a polyol having a molecular weight of 300 or more and 1200 or less is used, its content is not particularly limited and can be freely set. The lower limit of the content of the polyol having a molecular weight of 300 or more and 1200 or less in 100 parts by mass of the polyol component used in the present technology is, for example, 12.0 parts by mass or more, preferably 12.5 parts by mass or more, and more preferably 13.0 parts by mass or more. In particular, in the polyurethane foam according to the first embodiment described above, the lower limit of the content of the polyol having a molecular weight of 300 or more and 1200 or less in 100 parts by mass of the polyol component used in the present technology is preferably 14.0 parts by mass or more.

[0053] The upper limit of the content of the polyol having a molecular weight of 300 or more and 1200 or less in 100 parts by mass of the polyol component used in the present technology is, for example, 55 parts by mass or less, preferably 50 parts by mass or less, and more preferably 45 parts by mass or less. In particular, in the polyurethane foam according to the second embodiment described above, the upper limit of the content of the polyol having a molecular weight of 300 or more and 1200 or less in 100 parts by mass of the polyol component used in the present technology is preferably 35 parts by mass or less, more preferably 30 parts by mass or less, even more preferably 25 parts by mass or less, still more preferably 20 parts by mass or less, and particularly preferably 15 parts by mass or less.

[0054] In the present technology, it is preferable to use a polyol having a molecular weight of less than 200 as a chain extender.

[0055] When a polyol having a molecular weight of less than 200 is used, its content is not particularly limited and can be freely set. The lower limit of the content of the polyol having a molecular weight of less than 200 in 100 parts by mass of the polyol component used in the present technology is, for example, 2.0 parts by mass or more, preferably 5.0 parts by mass or more, more preferably 6.0 parts by mass or more, and even more preferably 7.0 parts by mass or more.

[0056] (1-2) Polymer Polyol In the present technology, it is preferable to use a polymer polyol as the polyol. The polymer polyol is one obtained by polymerizing an ethylenically unsaturated monomer in a polyol, or one obtained by emulsifying and dispersing a polymer of an ethylenically unsaturated monomer in a polyol. Specific examples include one obtained by graft-polymerizing acrylonitrile, styrene, or the like onto a polyol, or one obtained by dispersing polystyrene or polyacrylonitrile in a polyol.

[0057] When using a polymer polyol, its content is not particularly limited and can be freely set. The lower limit of the content of the polymer polyol in 100 parts by mass of the polyol component used in this technology is, for example, 5 parts by mass or more, preferably 10 parts by mass or more, more preferably 15 parts by mass or more. In particular, in the polyurethane foam according to the second embodiment described above, the lower limit of the content of the polymer polyol in 100 parts by mass of the polyol component used in this technology is preferably 20 parts by mass or more, more preferably 30 parts by mass or more, even more preferably 40 parts by mass or more, and even more preferably 45 parts by mass or more.

[0058] The upper limit of the content of the polymer polyol in 100 parts by mass of the polyol component used in the present technology is, for example, 70 parts by mass or less, preferably 65 parts by mass or less, and more preferably 63 parts by mass or less. In particular, in the polyurethane foam according to the first embodiment described above, the upper limit of the content of the polymer polyol in 100 parts by mass of the polyol component used in the present technology is preferably 50 parts by mass or less, more preferably 45 parts by mass or less, even more preferably 40 parts by mass or less, and still more preferably 35 parts by mass or less.

[0059] (1-3) Polyester Polyol In the present technology, it is preferable to use a polyester polyol as the polyol. Examples of polyester polyols include polylactone polyols and polycaprolactone polyols obtained by ring-opening polymerization of lactone monomers such as ε-caprolactone and methylvalerolactone; aliphatic dicarboxylic acids such as succinic acid, adipic acid, sebacic acid, and azelaic acid; aliphatic carboxylic acids such as ricinoleic acid; aromatic dicarboxylic acids such as phthalic acid, terephthalic acid, isophthalic acid, and naphthalenedicarboxylic acid; alicyclic dicarboxylic acids such as hexahydrophthalic acid, hexahydroterephthalic acid, and hexahydroisophthalic acid; Alternatively, polyester polyols such as polypropylene glycol obtained by a dehydration condensation reaction of these acid esters or acid anhydrides with ethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, 1,8-octanediol, 1,9-nonanediol, or the like, or a mixture thereof, can also be mentioned.

[0060] In addition, in the present technology, a biomass-derived polyol such as castor oil, which will be described later, can also be used as the polyester polyol.

[0061] When a polyester polyol is used as the polyol, its content can be freely set as long as it does not impair the action and effect of the present technology. The lower limit of the content of the polyester polyol in 100 parts by mass of the polyol component used in the present technology is, for example, 12.0 parts by mass or more, preferably 12.5 parts by mass or more, and more preferably 13.0 parts by mass or more. In particular, in the polyurethane foam according to the first embodiment described above, the lower limit of the content of the polyester polyol in 100 parts by mass of the polyol component used in the present technology is preferably 14.0 parts by mass or more.

[0062] The upper limit of the content of polyester polyol in 100 parts by mass of the polyol component used in the present technology is, for example, 55 parts by mass or less, preferably 50 parts by mass or less, and more preferably 45 parts by mass or less. In particular, in the polyurethane foam according to the second embodiment described above, the upper limit of the content of polyester polyol in 100 parts by mass of the polyol component used in the present technology is preferably 35 parts by mass or less, more preferably 30 parts by mass or less, even more preferably 25 parts by mass or less, still more preferably 20 parts by mass or less, and particularly preferably 15 parts by mass or less.

[0063] (1-4) Polyether Polyol In the present technology, it is preferable to use a polyether polyol as the polyol. Examples of polyether polyols include polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol, etc., which are obtained by polymerizing a cyclic ether such as ethylene oxide (EO), propylene oxide (PO), or tetrahydrofuran as an initiator, and copolyethers thereof. Polyether polyols can also be obtained by polymerizing the above-mentioned cyclic ethers using a polyhydric alcohol such as glycerin or trimethylolethane.

[0064] When a polyether polyol is used as the polyol, its content can be freely set as long as it does not impair the action and effect of the present technology. The lower limit of the content of polyether polyol per 100 parts by mass of the polyol component used in the present technology is, for example, 5 parts by mass or more, preferably 10 parts by mass or more, and more preferably 15 parts by mass or more.

[0065] The upper limit of the content of polyether polyol in 100 parts by mass of the polyol component used in the present technology is, for example, 55 parts by mass or less, preferably 50 parts by mass or less, and more preferably 45 parts by mass or less.

[0066] When a polyether polyol is used as the polyol, its molecular weight can be freely set as long as it does not impair the functions and effects of the present technology. In particular, in the polyurethane foam according to the first embodiment described above, it is preferable to use a polyether polyol having a molecular weight of 1,200 or more. Furthermore, in the polyurethane foam according to the second embodiment described above, it is preferable to use a polyether polyol having a molecular weight of 1,000 or less.

[0067] (1-5) Polyester Ether Polyol Examples of polyester ether polyols include those obtained by a dehydration condensation reaction of an aliphatic dicarboxylic acid such as succinic acid, adipic acid, sebacic acid, or azelaic acid; an aromatic dicarboxylic acid such as phthalic acid, terephthalic acid, isophthalic acid, or naphthalenedicarboxylic acid; an alicyclic dicarboxylic acid such as hexahydrophthalic acid, hexahydroterephthalic acid, or hexahydroisophthalic acid; or an acid ester or anhydride thereof with a glycol such as diethylene glycol or a propylene oxide adduct, or a mixture thereof.

[0068] (1-6) Polycarbonate Polyols Examples of polycarbonate polyols include those obtained by reacting at least one polyhydric alcohol such as ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, 1,8-octanediol, 1,9-nonanediol, or diethylene glycol with diethylene carbonate, dimethyl carbonate, diethyl carbonate, or the like.

[0069] (1-7) Biomass-Derived Polyol Examples of biomass-derived polyols that can be used in the present technology include 1,3-propanediol derived from plants and animals such as corn, 1,2,3-propanetriol (glycerin) derived from plants and animals, or condensates thereof, natural fats and oils such as castor oil, soybean oil, palm oil, palm kernel oil, coconut oil, cashew nut shell oil (CNSL (Cashew Nuts Shell Liquid)), cashew nut oil, olive oil, cottonseed oil, safflower oil, sesame oil, sunflower oil, and linseed oil, or derivatives thereof (for example, modified natural fat and oil polyols, unmodified natural fat and oil polyols, etc.).

[0070] (1-8) Biodegradable Polyols In consideration of the environment, biodegradable polyols can also be used in the present technology. As the biodegradable polyols that can be used in the present technology, one or more biodegradable polyols that can be used in the production of polyurethane foams can be freely selected and used, as long as the purpose and effects of the present technology are not impaired. Examples of biodegradable polyols that can be used in the present technology include polyglycolic acid (PGA), polylactic acid (PLA), polybutylene succinate (PBS), polybutylene succinate adipate (PBSA), polybutylene adipate terephthalate (PBAT), polycaprolactone (PCL), polyethylene glycol (PEG), polyvinyl alcohol (PVA), and polyhydroxyalkanoic acid (PHA).

[0071] (2) Isocyanate The isocyanate that can be used in the present technology can be freely selected from one or more isocyanates that can be used to produce polyurethane foam, as long as it does not impair the purpose and effects of the present technology. Examples include aliphatic isocyanates such as hexamethylene diisocyanate, isophorone diisocyanate, and dicyclohexylmethane diisocyanate; aromatic isocyanates such as toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), naphthalene diisocyanate, xylylene diisocyanate, and polymeric polyisocyanate; and modified polyisocyanates obtained by modifying these. Among these, in the present technology, it is preferable to use diphenylmethane diisocyanate (MDI) as the isocyanate.

[0072] The isocyanate index of the polyurethane foam is also not particularly limited as long as it does not impair the functions and effects of the present technology. In the present technology, the lower limit of the isocyanate index is, for example, 75 or more, preferably 80 or more, and more preferably 85 or more. By setting the lower limit of the isocyanate index within this range, it is possible to suppress deterioration of the compression set of the polyurethane foam produced, prevent sagging of the polyurethane foam, and improve cushioning performance.

[0073] The upper limit of the isocyanate index is, for example, not more than 120, preferably not more than 115, and more preferably not more than 110. By setting the upper limit of the isocyanate index within this range, the elongation percentage of the polyurethane foam can be improved.

[0074] In the present technology, the isocyanate index is a value calculated by [(isocyanate equivalent in the composition for producing polyurethane foam / active hydrogen equivalent in the composition for producing polyurethane foam)×100].

[0075] (3) Foam Stabilizer A foam stabilizer can be used in the production of polyurethane foam according to the present technology. By using a foam stabilizer, a better quality polyurethane foam can be produced.

[0076] The foam stabilizer that can be used in the present technology can be freely selected from one or more foam stabilizers that can be used in the production of polyurethane foam, as long as the action and effect of the present technology are not impaired. Examples include silicone-based foam stabilizers, fluorine-containing compound-based foam stabilizers, surfactants, etc. Silicone-based foam stabilizers include those composed mainly of siloxane chains, those in which the siloxane chain and polyether chain have a linear structure, those that are branched, and those in which the polyether chain is modified to have a pendant structure on the siloxane chain. Among these, it is preferable to use a silicone-based foam stabilizer in the present technology.

[0077] The amount of foam stabilizer in the composition used to produce the polyurethane foam according to the present technology can be freely set as long as it does not impair the action and effect of the present technology. The lower limit of the content of the foam stabilizer in the composition is, for example, 1 part by mass or more, preferably 3 parts by mass or more, and more preferably 5 parts by mass or more, per 100 parts by mass of polyol. The upper limit of the content of the moisture absorbent in the composition is, for example, 15 parts by mass or less, preferably 10 parts by mass or less, and more preferably 8.0 parts by mass or less, per 100 parts by mass of polyol.

[0078] (4) Catalyst A catalyst can be used in the production of polyurethane foam according to the present technology. As the catalyst that can be used in the present technology, one or more catalysts that can be used in the production of polyurethane foam can be freely selected and used, as long as the action and effect of the present technology are not impaired.

[0079] Examples of the catalyst include metal catalysts (organometallic catalysts) such as organic iron compounds (iron acetylacetonate, etc.), organic nickel compounds (nickel acetylacetonate, nickel octoate, nickel naphthenate, etc.), organic tin compounds (tin (II) octoate (tin 2-ethylhexanoate, stannous octoate, etc.), organic bismuth compounds (bismuth octoate, bismuth naphthenate, etc.), organic lead compounds (lead octoate, lead naphthenate, etc.), organic cobalt compounds (cobalt acetylacetonate, cobalt octoate, cobalt naphthenate, etc.), organic zirconium compounds (zirconium acetylacetonate, etc.), and organic zinc compounds; triethylamine, triethylenediamine (TEDA), tetramethylguanidine, and diethanolamine. , bis(2-dimethylaminoethyl)ether, N,N,N',N",N"-pentamethyldiethylenetriamine, imidazole-based compounds, piperazine-based amines such as dimethylpiperazine, N-methyl-N'-(2-dimethylamino)ethylpiperazine, and N-methyl-N'-(2-hydroxyethyl)piperazine, morpholine-based amines such as N-methylmorpholine and N-ethylmorpholine, and amines known as DBU homologues such as 1,8-diazabicyclo-[5,4,0]-undecene-7 (DBU), 1,5-diazabicyclo-[4,3,0]-nonene-5 (DBN), 1,8-diazabicyclo-[5,3,0]-decene-7 (DBD), and 1,4-diazabicyclo-[3,3,0]octene-4 (DBO).

[0080] The amount of catalyst in the composition used to produce the polyurethane foam according to the present technology can be freely set as long as it does not impair the function and effect of the present technology. In the present technology, the lower limit of the catalyst content in the composition is, for example, 0.1 parts by mass or more, preferably 0.5 parts by mass or more, and more preferably 1.0 parts by mass or more, per 100 parts by mass of polyol. By setting the lower limit of the catalyst content in the composition within this range, various reactions during production can be controlled, and as a result, polyurethane foam with excellent mechanical properties and appearance can be obtained.

[0081] In this technology, the upper limit of the catalyst content in the composition is, for example, 15 parts by mass or less, preferably 12 parts by mass or less, and more preferably 10 parts by mass or less, per 100 parts by mass of polyol. By setting the upper limit of the catalyst content in the composition within this range, it is possible to prevent destabilization of various reactions during production. As a result, a polyurethane foam with excellent mechanical properties and appearance can be obtained.

[0082] (5) Antioxidant An antioxidant can be used in the production of polyurethane foam according to the present technology. As the antioxidant that can be used in the present technology, one or more antioxidants that can be used in the production of polyurethane foam can be freely selected and used, as long as the action and effect of the present technology are not impaired. For example, one or more antioxidants can be freely combined and used from phenol-based (monophenol-based, thiobisphenol-based, hindered phenol-based), naphthylamine-based, diphenylamine-based, p-phenyldiamine-based, quinoline-based, hydroquinone derivatives, phosphite ester-based, etc. Among these, in the present technology, it is preferable to use a phenol-based antioxidant as the antioxidant.

[0083] The amount of antioxidant in the composition used to produce the polyurethane foam according to the present technology can be freely set as long as it does not impair the action and effect of the present technology. In the present technology, the lower limit of the content of antioxidant in the composition is, for example, 0.01 parts by mass or more, preferably 0.03 parts by mass or more, and more preferably 0.05 parts by mass or more, per 100 parts by mass of polyol.

[0084] In the present technology, the upper limit of the content of the antioxidant in the composition is, for example, 5 parts by mass or less, preferably 3 parts by mass or less, and more preferably 1 part by mass or less, per 100 parts by mass of the polyol.

[0085] (6) Filler The filler that can be used in the present technology can be freely selected from one or more fillers that can be used in the production of polyurethane foam, as long as it does not impair the purpose and effects of the present technology. When producing polyurethane foam using the mechanical froth method, the filler also functions as a nucleating agent (foaming base point). Examples of fillers include metal hydroxides such as calcium carbonate, aluminum hydroxide, and magnesium hydroxide, alumina trihydrate, silica, talc, calcium carbonate, and clay. Among these, metal hydroxides are preferred as fillers in the present technology, and among metal hydroxides, aluminum hydroxide is more preferred.

[0086] The amount of filler in the composition used to produce the polyurethane foam according to the present technology can be freely set as long as it does not impair the function and effect of the present technology. In the present technology, the lower limit of the filler content in the composition is, for example, 5 parts by mass or more, preferably 10 parts by mass or more, and more preferably 15 parts by mass or more, per 100 parts by mass of polyol. The upper limit of the filler content in the composition is, for example, 35 parts by mass or less, preferably 30 parts by mass or less, more preferably 25 parts by mass or less, and even more preferably 23 parts by mass or less, per 100 parts by mass of polyol.

[0087] (7) Moisture absorbent A moisture absorbent can be used in the production of polyurethane foam according to the present technology. The use of a moisture absorbent can prevent unintended foaming due to moisture contained in the reaction atmosphere or materials. It is particularly preferable to use a moisture absorbent when producing polyurethane foam by the mechanical froth method. As the moisture absorbent that can be used in the present technology, one or more moisture absorbents that can be used in polyurethane foam can be freely selected and used, as long as the action and effect of the present technology are not impaired. Examples of moisture absorbents include zeolite, silica gel, calcium oxide, activated carbon, potassium hydroxide, sodium hydroxide, and lithium hydroxide. Among these, it is preferable to use zeolite as the moisture absorbent in the present technology.

[0088] The amount of moisture absorbent in the composition used to produce polyurethane foam according to the present technology can be freely set as long as it does not impair the function and effect of the present technology. In the present technology, the lower limit of the content of the moisture absorbent in the composition is, for example, 0.1 parts by mass or more, preferably 0.3 parts by mass or more, and more preferably 0.5 parts by mass or more, per 100 parts by mass of polyol. The upper limit of the content of the moisture absorbent in the composition is, for example, 3.0 parts by mass or less, preferably 2.5 parts by mass or less, and more preferably 2.0 parts by mass or less, per 100 parts by mass of polyol.

[0089] (8) Foam-forming gas A foam-forming gas can be used in the production of polyurethane foam according to the present technology. As the foam-forming gas that can be used in the present technology, one or more foam-forming gases that can be used in the production of polyurethane foam can be freely selected and used, as long as the action and effect of the present technology are not impaired.

[0090] Examples of foam-forming gases include dry air and inert gases such as nitrogen. The mixing ratio of the foam-forming gas with other raw materials can be freely set depending on the application of the polyurethane foam to be produced, as long as it does not impair the purpose and effects of the present technology. In the present technology, the mixing ratio of the foam-forming gas with other raw materials can be set to, for example, 10% by volume or more, preferably 15% by volume or more, and more preferably 20% by volume or more, based on 100% by volume of the foam-forming gas and other raw materials combined.

[0091] In this technology, the upper limit of the mixing ratio of the foam-forming gas with other raw materials can be set to, for example, 100 volume % or less, 95 volume % or less, or 90 volume % or less out of 100 volume % of the foam-forming gas and other raw materials combined.

[0092] (9) Others In the production of polyurethane foam according to the present technology, one or more of various components that can be used in the production of polyurethane foam can be freely selected and used as other components depending on the purpose, as long as the action and effect of the present technology are not impaired.

[0093] Examples of components that can be used in producing polyurethane foams according to the present technology include flame retardants, pigments, stabilizers, plasticizers, colorants, crosslinking agents, antibacterial agents, dispersants, and ultraviolet absorbers.

[0094] 3. Method for Producing Polyurethane Foam The polyurethane foam according to the present technology can be produced by mixing the components of the composition described above to prepare a composition, and foaming the prepared composition by a known method. Specific methods for the composition preparation step, foaming step, etc. can be freely combined with conventional methods as long as they do not impair the functions and effects of the present technology.

[0095] In the method for producing polyurethane foam according to the present technology, it is particularly preferable to use a mechanical froth method. By using the mechanical froth method, it is easier to adjust the density compared to chemical foaming methods, and high-density polyurethane foam can be produced. It is also possible to produce thin polyurethane foam.

[0096] As a specific method for the mechanical froth method, a general mechanical froth method can be used as long as it does not impair the functions and effects of the present technology. For example, the raw materials of the above-mentioned composition other than the isocyanate and foam-forming gas are charged into a mixing head and mixed at a timing appropriate for the type and purpose of each raw material to prepare an intermediate composition. The isocyanate is charged into the prepared intermediate composition, and while mixing, the foam-forming gas is mixed in, and the mixture is stirred and mixed to become homogeneous. Then, the mixture is heated and cured on release paper or in a mold, whereby a polyurethane foam can be produced.

[0097] 4. Sheets The polyurethane foam according to the present technology can be suitably used for sheet materials. The thickness of the sheet material according to the present technology can be freely set as long as it does not impair the purpose and effect of the present technology.

[0098] The lower limit of the thickness of the polyurethane foam according to the present disclosure is, for example, 1.0 mm or more, preferably 2.0 mm or more, and more preferably 3.0 mm or more. By setting the thickness of the polyurethane foam within this range, better impact absorption properties can be achieved.

[0099] The upper limit of the thickness of the polyurethane foam according to the present technology can also be freely set as long as it does not impair the purpose and effects of the present technology, but is, for example, 25 mm or less, preferably 20 mm or less, more preferably 18 mm or less, and even more preferably 15 mm or less.

[0100] Taking advantage of its high quality, the sheet material according to the present technology can be used for a wide variety of purposes in a wide range of fields, including insoles, shock absorbing materials, armrests, headrests, footrests, shoulder pads for bags, cushioning materials for everyday items, and protectors for sports.

[0101] The present technology will be described in more detail below based on examples. Note that the examples described below are examples of typical examples of the present technology, and the scope of the present technology will not be narrowed by these examples.

[0102] (1) Raw Materials The raw materials used in this example are shown in Table 1 below.

[0103]

[0104] (2) Sample Production Compositions were prepared using the blending ratios shown in Figure 1 and Tables 2 to 4, and polyurethane foams of each Example and Comparative Example were produced by the mechanical froth method. Specifically, the components shown in Tables 2 to 4 below were prepared in the blending ratios shown in Tables 2 to 4 below to obtain mixed raw materials for each Example and Comparative Example. The mixed raw materials were then charged into a mixing head and stirred to homogeneity while mixing in a foam-forming gas (inert gas: nitrogen), followed by heat curing to form polyurethane foam samples into the shape of test pieces used to measure the physical properties described below.

[0105] (3) Measurement and Evaluation of Physical Properties [Density] Using a 50 x 50 mm prismatic test piece, the density was measured by a method in accordance with JIS K6401:2011.

[0106] [Tensile Strength] Using a test piece having a dumbbell No. 3 shape shown in FIG. 3, the tensile strength was measured by a method in accordance with JIS K6251:2010.

[0107] [Elongation] Using a test piece having a dumbbell No. 3 shape shown in FIG. 3, the elongation was measured by a method in accordance with JIS K6251:2010.

[0108] [Tear Strength] Using the angle-shaped punched test piece shown in FIG. 4, tear strength was measured by a method in accordance with JIS K6252:2007.

[0109] [Compression Set] Compression set was measured using a 50 x 50 mm prismatic test piece according to JIS K6401:2011.

[0110] [Impact absorption] A 5.3 kg weight was allowed to fall freely under the following test conditions, and the impact load (kN) received by the sensor below the sample was confirmed (see Figure 5): [Test condition 1] Sample temperature: -20°C (sample cooled) Sample thickness: 9 mm Drop height: 500 mm [Test condition 2] Sample temperature: 22°C Sample thickness: 9 mm Drop height: 500 mm [Test condition 3] Sample temperature: 22°C Sample thickness: 21 mm Drop height: 1.2 m

[0111] [Glass transition temperature] [Loss tangent tanδ] Testing machine: Using an ARES-G2 rheometer manufactured by TA Instruments, the maximum value, minimum value, difference between the maximum and minimum values ​​of tanδ, and the temperature at the peak of tanδ (glass transition temperature) were measured in the temperature range of -10°C to 20°C under the conditions of a temperature range of -40°C to 80°C (heating rate: 3°C / min), a mode: parallel plate mode (φ8 mm), a strain: 0.5%, and a frequency: 1.0 Hz.

[0112] [Bending cracking] A sample having a thickness of 3 mm was manually bent 180° at −20° C. to check whether it would crack. If it did not crack, it was evaluated as ○, and if it cracked, it was evaluated as ×.

[0113] (4) Results The results are shown in Tables 2 to 4 below, and in Figures 2 and 6.

[0114]

[0115]

[0116] (4) Discussion As shown in Tables 2 to 4, Figures 2 and 6, the polyurethane foams of Examples 1 to 4 and 6 to 10-1, which satisfied the loss tangent tanδ ≧ 0.2 over the entire temperature range of 10 to 20°C, exhibited good impact absorption results in both the low temperature range (−20°C) and the normal temperature range (22°C). On the other hand, the polyurethane foam of Comparative Example 1, which did not satisfy the loss tangent tanδ ≧ 0.2 over the entire temperature range of 10 to 20°C, exhibited good impact absorption results in the low temperature range (−20°C), but poor impact absorption results in the normal temperature range (22°C).

[0117] Comparing the examples, the polyurethane foams of Examples 7, 8, 9-1 to 9-2, and 10-1, in which the difference between the maximum value of tan δ in the temperature range of -20 to 40°C and the tan δ at -20°C was 0.40 or less, showed better results in the flexural crack evaluation at -20°C than the polyurethane foam of Example 5, in which the difference was 0.40 or less. The elongation of the polyurethane foam of Example 5 was less than 150%.

Claims

1. A polyurethane foam that satisfies the loss tangent tanδ≧0.2 over the entire temperature range of 10 to 20°C.

2. Density is 100 kg / m ３ The polyurethane foam according to claim 1 .

3. The polyurethane foam according to claim 1 or 2, which has only one glass transition point in the temperature range of -20 to 40°C.

4. A polyurethane foam according to any one of claims 1 to 3, in which the difference between the maximum value of tan δ in the temperature range of -20 to 40°C and the tan δ at -20°C is 0.40 or less.

5. The polyurethane foam according to any one of claims 1 to 4, having an elongation percentage of 150% or more.

6. The polyurethane foam according to any one of claims 1 to 5, having a glass transition point of 10°C or lower.

7. The polyurethane foam according to any one of claims 1 to 5, having a glass transition point of 15°C or higher.

8. A sheet material comprising a polyurethane foam according to any one of claims 1 to 7.

9. The sheet material according to claim 8, having a thickness of 20 mm or less.

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