Sheet and soundproofing material

Abstract

Provided is a sheet that is excellent in vibration damping over a wide frequency band. The sheet includes at least two types of elastomer-based resins. Domains are present within the sheet. The average domain size is 5 μm or less. The domains are components derived from elastomer-based resins. For example, the sheet may be composed of a copolymer or a hydrogenated product thereof, in which each of the at least two types of elastomeric resins includes a polystyrene-based hard segment and a vinyl–polydiene-based soft segment.

Description

Seats and soundproofing Related Applications

[0001] This application claims priority from Japanese Patent Application No. 2024-068327, filed on April 19, 2024, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to a sheet containing an elastomeric resin and a soundproofing material containing the sheet.

[0003] In recent years, hybrid electric vehicles (HEVs) and electric vehicles (EVs), which include electric motors as their driving sources, have become increasingly popular, replacing automobiles that are driven solely by engines. The electrification of automobiles has significantly improved quietness, as it eliminates engine noise, which is the main noise generated in conventional automobiles. As a result, there is a demand for reducing road noise, etc., generated between the ground and tires, which was not a problem in conventional automobiles.

[0004] Therefore, noise reduction using vibration-damping materials has been investigated, and vibration-damping materials containing rubber materials have been proposed as materials with excellent vibration damping properties. For example, Patent Document 1 (JP-A-7-68696) discloses a steel plate vibration-damping reinforcement sheet comprising a constraining layer, a viscoelastic layer, and a thermosetting resin layer, the viscoelastic layer having a loss tangent of 0.8 or greater at temperatures between −20°C and 80°C, and characterized in that the constraining layer, viscoelastic layer, and thermosetting resin layer are laminated in this order. It also describes that the thermosetting resin layer is formed by blending a mixture of rubber having a number-average molecular weight of 500 to 20,000 and at least one thermoplastic elastomer, and that the viscoelastic layer is formed by mixing and dispersing various additives in a resin such as various thermoplastic elastomers, rubber-based resins such as liquid rubber, etc.

[0005] Patent Document 2 (JP 2013-160317 A) discloses a vibration-damping material that can be used over a wide temperature range and is made up of a constraining layer and an adhesive layer, wherein the adhesive layer contains (a) butyl rubber, (b) a tackifier made of a terpene resin and a C5 fraction aliphatic petroleum resin, (c) an adhesion-enhancing agent made of two types of polybutene resins with different molecular weights, (d) a fiber component made of organic fiber and glass fiber, (e) a carbon material, (f) a softener, and (g) an inorganic filler.

[0006] Vibration-damping materials containing thermoplastic elastomers have also been proposed. For example, Patent Document 3 (WO 2019 / 069684) discloses a vibration-damping sheet comprising a thermoplastic elastomer sheet having a large number of through-holes and a pressure-sensitive adhesive layer present on one or both sides of the thermoplastic elastomer sheet, wherein the thermoplastic elastomer sheet has an aperture ratio of 5 to 80% and a loss factor tanδ of 0.3 or greater at 0°C and 30 Hz.

[0007] Japanese Patent Application Laid-Open No. 7-68696 Japanese Patent Application Laid-Open No. 2013-160317 International Publication No. 2019 / 069684

[0008] Vibration damping properties are generally evaluated by the loss factor tan δ obtained by dynamic viscoelasticity measurement, and increasing tan δ in a frequency band of about 1 to 1000 Hz is effective in reducing road noise, etc. This frequency band corresponds to a temperature range of about 0 to 40°C according to the frequency-temperature conversion rule, and if the temperature range in which tan δ is high is wide, it can be said that the material has high vibration damping properties over a wide frequency band.

[0009] In Patent Documents 1 and 2, the loss factors of the damping material at various temperatures are measured in the examples, but the loss factors are not sufficiently high, and there is room for improvement.

[0010] Patent Document 3 describes an embodiment of a vibration-damping sheet containing multiple thermoplastic elastomers, and describes a vibration-damping sheet with a high tan δ at 0°C measured in the examples, but only tan δ at 0°C is measured, and vibration-damping properties over a wide temperature range (frequency band) are not evaluated.

[0011] Therefore, an object of the present invention is to provide a seat that has excellent vibration damping properties over a wide frequency range.

[0012] As a result of extensive investigations to solve the above problems, the present inventors have found that a sheet containing two or more types of elastomeric resins, in which domains exist and the average domain size is small within a specific range, can more evenly blend the temperature dependence curves of tan δ of the individual elastomeric resins, thereby widening the temperature region (frequency band) in which tan δ is high, and have completed the present invention.

[0013] That is, the present invention can be configured in the following aspects. [Aspect 1] A sheet containing two or more types of elastomeric resins, wherein domains are present in the sheet, the average domain size is 5 μm or less (preferably 1 μm or less, more preferably 0.1 μm or less, even more preferably 0.05 μm or less, and even more preferably 0.015 μm or less), and the domains are components derived from the elastomeric resins. [Aspect 2] The sheet according to Aspect 1, wherein the two or more types of elastomeric resins are both copolymers having a polystyrene-based hard segment and a vinyl-polydiene-based soft segment, or hydrogenated products thereof (preferably hydrogenated products). [Aspect 3] The sheet according to Aspect 1 or 2, wherein the glass transition temperature Tg of the elastomeric resin having the highest glass transition temperature among the elastomeric resins is 0.015 μm or less. Ｈ and the glass transition temperature Tg of the elastomer resin having the lowest glass transition temperature Ｌand the difference between the glass transition temperature and the total glass transition temperature is 5 to 60°C (preferably 8 to 50°C, more preferably 10 to 40°C, and even more preferably 15 to 30°C). [Aspect 4] The sheet according to any one of Aspects 1 to 3, wherein the weight percentage of the elastomer resin having the lowest glass transition temperature among the elastomer resins is equal to or greater than the weight percentage of the elastomer resin having the highest glass transition temperature. [Aspect 5] The sheet according to any one of Aspects 1 to 4, wherein the peak temperature of the loss factor tan δ calculated by dynamic viscoelasticity measurement is within the range of 0 to 40°C (preferably 5 to 37°C, more preferably 8 to 35°C, and even more preferably 10 to 30°C). [Aspect 6] The sheet according to any one of Aspects 1 to 5, wherein the integral value of the temperature dependence curve of the loss factor tan δ obtained by dynamic viscoelasticity measurement over the range of 0 to 40°C where the loss factor tan δ is 0.2 or more is 25 or more (preferably 30 or more, more preferably 32 or more, and even more preferably 35 or more). [Aspect 7] The sheet according to any one of Aspects 1 to 6, which is a nonwoven fabric. [Aspect 8] The sheet according to Aspect 7, which is a long-fiber nonwoven fabric (preferably a meltblown nonwoven fabric). [Aspect 9] The sheet according to any one of Aspects 1 to 8, which has an apparent density of 0.10 g / cm ３ or more (preferably 0.20 to 0.50 g / cm ３ , more preferably 0.25 to 0.45 g / cm ３ , more preferably 0.27 to 0.40 g / cm ３ Aspect 10: The sheet according to any one of aspects 1 to 9, wherein the sheet has an air permeability of 100 cm ３ / cm ２ ・s or less (preferably 10 to 50 cm ３ / cm ２ s, more preferably 12 to 40 cm ３ / cm ２ s, more preferably 13 to 30 cm ３ / cm ２A sheet, wherein the sheet is (s). [Aspect 11] A soundproofing material comprising the sheet according to any one of aspects 1 to 10. [Aspect 12] The soundproofing material according to aspect 11, which is for vehicles, buildings, or acoustic equipment.

[0014] As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms, including "at least one," unless the content clearly dictates otherwise. As used herein, the terms "and / or," "at least one," and "one or more" include any and all combinations of the associated listed items.

[0015] It should be noted that any combination of at least two elements disclosed in the claims and / or the specification and / or the drawings is included in the present invention, and in particular any combination of two or more of the claims set forth in the claims is included in the present invention.

[0016] The sheet of the present invention has excellent vibration damping properties over a wide frequency range and can be used as a variety of soundproofing materials for sounds corresponding to those frequency ranges.

[0017] 1 is a graph showing a temperature dependency curve of loss factor tan δ obtained by dynamic viscoelasticity measurement of the sheet obtained in Example 1. FIG. 2 is a graph showing a temperature dependency curve of loss factor tan δ obtained by dynamic viscoelasticity measurement of the sheet obtained in Example 2. FIG. 3 is a graph showing a temperature dependency curve of loss factor tan δ obtained by dynamic viscoelasticity measurement of the sheet obtained in Example 3. FIG. 4 is a graph showing a temperature dependency curve of loss factor tan δ obtained by dynamic viscoelasticity measurement of the sheet obtained in Example 4. FIG. 5 is a graph showing a temperature dependency curve of loss factor tan δ obtained by dynamic viscoelasticity measurement of the sheet obtained in Comparative Example 1.

[0018] The sheet contains two or more types of elastomer resins, which are copolymers composed of hard segments (polymer blocks) and soft segments (polymer blocks), and specific examples of the elastomer resins include styrene elastomers, olefin elastomers, urethane elastomers, ester elastomers, amide elastomers, and vinyl chloride elastomers, depending on the type of hard segment.

[0019] From the viewpoint of excellent tan δ characteristics at around 0 to 40°C, the elastomer resin is preferably a copolymer having a polystyrene hard segment and a vinyl-polydiene soft segment or a hydrogenated product thereof, and from the viewpoint of sheet formability, a hydrogenated product of a copolymer having a polystyrene hard segment and a vinyl-polydiene soft segment is more preferable.

[0020] The polystyrene-based hard segment may have a structural unit derived from styrene or a derivative thereof. Examples of styrene derivatives include α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, and 1,3-dimethylstyrene. Styrene and its derivatives may be used alone or in combination of two or more. When two or more structural units derived from styrene or its derivatives are used, the respective structural units in the polystyrene-based hard segment may be a random copolymer.

[0021] The vinyl-polydiene soft segment may have a structural unit derived from a conjugated diene such as butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, or 1,3-hexadiene. The conjugated dienes may be used alone or in combination of two or more. The structural unit derived from the conjugated diene may be a 1,2-bond unit and / or a 1,4-bond unit. When two or more structural units derived from the conjugated diene are used, the respective structural units in the vinyl-polydiene soft segment may be a random copolymer.

[0022] A hydrogenated copolymer having a polystyrene-based hard segment and a vinyl-polydiene-based soft segment is a copolymer in which unsaturated double bonds in the structural units derived from the conjugated diene in the vinyl-polydiene-based soft segment have been hydrogenated, and is preferred from the viewpoint of melt moldability.

[0023] The two or more types of elastomeric resins may include elastomeric resins that differ in the types of hard segments and soft segments, the ratio of hard segments to soft segments, and / or the molecular weight of the copolymer. For example, with respect to the types of hard segments and soft segments, elastomeric resins having different types of hard segments and / or soft segments may be used as long as the average domain size is small. However, from the viewpoint of improving compatibility, elastomeric resins having the same types of hard segments and / or soft segments are preferred. From the viewpoint of excellent tan δ characteristics at around 0 to 40°C, it is preferred that all of the two or more types of elastomeric resins be copolymers having polystyrene-based hard segments and vinyl-polydiene-based soft segments or hydrogenated copolymers thereof. From the viewpoint of sheet formability, it is more preferred that all of the two or more types of elastomeric resins be hydrogenated copolymers having polystyrene-based hard segments and vinyl-polydiene-based soft segments.

[0024] The two or more elastomer resins preferably have different glass transition temperatures. For example, from the viewpoint of broadening the temperature range in which tan δ is high, the glass transition temperature Tg of the elastomer resin having the highest glass transition temperature among the elastomer resins is Ｈ and the glass transition temperature Tg of the elastomer resin having the lowest glass transition temperature Ｌ The difference between the glass transition temperature and the glass transition temperature may be 5 to 60° C., preferably 8 to 50° C., more preferably 10 to 40° C., and even more preferably 15 to 30° C. In this specification, the glass transition temperature is the peak temperature in the temperature dependency curve of tan δ in dynamic viscoelasticity measurement, and is a value measured by the method described in the Examples below.

[0025] The glass transition temperature of each of the elastomer resins may be in the range of -60 to 50°C, preferably in the range of -40 to 40°C, and more preferably in the range of -10 to 30°C.

[0026] From the viewpoint of compatibility, the difference Δδ (cal / cm) between the solubility parameter δ (SP value) of the elastomer resin and the solubility parameter Δδ (SP value) of the elastomer resin having the highest solubility parameter and the elastomer resin having the lowest solubility parameter is ３ ) １／２ may be 2.0 or less, preferably 1.5 or less, more preferably 1.0 or less, and even more preferably 0.5 or less. In this specification, the solubility parameter δ is a value determined by the Fedors estimation method and is calculated from the following formula: δ=(E / V) １／２ (where E is the molecular cohesive energy (cal / mol) and is calculated as the sum of the evaporation energies of the atoms or atomic groups that constitute the compound, and V is the molecular volume (cm ３ / mol) and is calculated as the sum of the molar volumes of the atoms or atomic groups that constitute the compound.

[0027] The weight ratio of the elastomer resin having the lowest glass transition temperature among the elastomer resins may be equal to or greater than the weight ratio of the elastomer resin having the highest glass transition temperature. For example, the weight ratio of the elastomer resin having the lowest glass transition temperature to the elastomer resin having the highest glass transition temperature (former / latter) may be 50 / 50 to 99 / 1, preferably 60 / 40 to 95 / 5, and more preferably 70 / 30 to 93 / 7.

[0028] Domains exist in the sheet, and the average domain size is 5 μm or less. By incorporating two or more types of elastomeric resins and reducing the domain size within a specific range, the elastomeric resins are in a compatible state, allowing the tan δ characteristics of each elastomeric resin to be effectively combined and exhibited. In other words, while the temperature range in which tan δ is high is narrow when each elastomeric resin is used alone, by more homogeneously fusing the temperature dependence curves of each tan δ, the temperature range in which tan δ is high can be widened, allowing vibration damping properties to be exhibited over a wide frequency range.

[0029] In this specification, the term "domain" refers to a phase-separated structure formed by each component in a sheet at room temperature, where one component forms a dispersed phase in a matrix formed by another component. Here, each component may be any component derived from an elastomeric resin, and may be each elastomeric resin itself or each segment of the elastomeric resin. The presence of domains can be confirmed by observation with a scanning probe microscope (SPM). The shape of the domains is not particularly limited as long as their presence can be confirmed in the sheet, and they may be in the form of particles that are not continuous when observed from any direction.

[0030] In this specification, the domain size is calculated by measuring the area of ​​each dispersed phase dispersed in a matrix and assuming that the dispersed phase is a perfect circle, and the average domain size is a value measured by the method described in the Examples below. The average domain size may be preferably 1 μm or less, more preferably 0.1 μm or less, even more preferably 0.05 μm or less, and even more preferably 0.015 μm or less. If the average domain size in the sheet is too large, the compatibility of the elastomer resins will be poor, resulting in poor fusion of the peaks in the temperature dependence curves of tan δ of the elastomer resins, resulting in multiple peaks, and making it impossible to widen the temperature range where tan δ is high. The lower limit of the average domain size is not particularly limited, but may be, for example, 0.001 μm or more.

[0031] From the viewpoint of improving vibration damping properties in a frequency band of about 1 to 1000 Hz, the peak temperature of the loss factor tan δ calculated by dynamic viscoelasticity measurement of the sheet may be in the range of 0 to 40°C, preferably 5 to 37°C, more preferably 8 to 35°C, and even more preferably 10 to 30°C. The peak of the temperature dependence curve of tan δ is preferably unimodal from the viewpoint of widening the temperature range in which tan δ shows continuously high values. In this specification, the peak of the temperature dependence curve of tan δ is considered to be the point where tan δ increases from the low-temperature side to the high-temperature side, reaches a maximum value (maximum value in the case of a unimodal curve), and then tan δ decreases; minute fluctuations (noise, etc.) are not considered to be peaks. In this specification, the temperature dependence curve of loss factor tan δ is measured by the method described in the Examples below. In the case of a multimodal curve, the peak temperature of tan δ is the peak temperature of the peak at which tan δ shows a maximum value.

[0032] In a temperature dependency curve of loss factor tan δ obtained by measuring the dynamic viscoelasticity of the sheet, tan δ may be 0.2 or more in a temperature range of at least 15 to 40° C., preferably at least 10 to 50° C., and more preferably at least 5 to 50° C. A tan δ of 0.2 or more can be regarded as an index of exhibiting vibration-damping properties.

[0033] Since the sheet has excellent vibration damping properties over a wide frequency band, in a temperature dependency curve of loss factor tan δ obtained by measuring the dynamic viscoelasticity of the sheet, the integral value in the range where the loss factor tan δ is 0.2 or more in the temperature range of 0 to 40°C may be 25 or more, preferably 30 or more, more preferably 32 or more, and even more preferably 35 or more.

[0034] In a temperature dependency curve of loss factor tan δ obtained by measuring the dynamic viscoelasticity of the sheet, the loss factor tan δ at 20° C. may be 0.8 or more, preferably 1.0 or more, and more preferably 1.2 or more.

[0035] The sheet may contain components other than the elastomeric resin, such as various additives, as long as the effects of the present invention are not impaired. In this case, as described above, the domains in the sheet are dispersed phases formed by components derived from the elastomeric resin, and therefore, in this specification, the dispersed phases formed by the additives and the like are not considered to be domains.

[0036] The shape of the sheet is not particularly limited as long as the average domain size satisfies the above range, and may be, for example, a fabric such as a woven fabric, a knitted fabric, or a nonwoven fabric, or a film. From the viewpoint of use as a soundproofing material, it is preferable that the sheet is porous and has breathability to improve sound absorption. Examples include nonwoven fabrics and porous films, and nonwoven fabrics are more preferred. The structure of the nonwoven fabric is not particularly limited as long as the average domain size satisfies the above range, and may be a wet-laid nonwoven fabric, a dry-laid nonwoven fabric, a long-fiber nonwoven fabric, etc., but long-fiber nonwoven fabrics are preferred. Long-fiber nonwoven fabrics are nonwoven fabrics composed of fibers that are continuous to a certain length and can be distinguished from nonwoven fabrics composed of short fibers that are intentionally cut to a predetermined fiber length. Examples include meltblown nonwoven fabrics and spunbonded nonwoven fabrics. From the viewpoint of being able to reduce the fiber diameter and improve density, meltblown nonwoven fabrics are more preferred. Spunbond nonwoven fabrics are made up of continuous filaments, whereas meltblown nonwoven fabrics are made up of filaments of a finite length, although they have a certain length, and can be distinguished from nonwoven fabrics made up of short fibers that are intentionally cut as described above.

[0037] From the viewpoint of improving sound absorption, for example, the air permeability of the sheet is set to 100 cm ３ / cm ２ ・It may be less than 10 cm, preferably 10 to 50 cm ３ / cm ２ s, more preferably 12 to 40 cm ３ / cm ２ s, more preferably 13 to 30 cm ３ / cm ２ In this specification, the air permeability is a value measured by the method described in the Examples below.

[0038] From the viewpoint of increasing the loss factor tanδ, it is preferable that the sheet has excellent density. For example, the apparent density of the sheet is 0.10 g / cm ３ or more, preferably 0.20 g / cm ３ More preferably, 0.25 g / cm ３ More preferably, 0.27 g / cm ３ In order to provide a certain degree of breathability, the apparent density of the sheet is preferably 0.50 g / cm ３ or less, more preferably 0.45 g / cm ３ More preferably, 0.40 g / cm or less ３ In this specification, the apparent density of the sheet is calculated from the basis weight and thickness of the sheet, and is a value measured by the method described in the examples below.

[0039] The basis weight of the sheet is, for example, 10 to 100 g / m ２ and preferably 15 to 90 g / m ２ , more preferably 20 to 80 g / m ２ The thickness of the sheet may be, for example, 0.1 to 1 mm, preferably 0.15 to 0.8 mm, and more preferably 0.2 to 0.5 mm. The basis weight and thickness of the sheet can be measured by a method conforming to the standard depending on the shape of the sheet, for example, JIS L 1913 for nonwoven fabrics, JIS L 1096 for woven fabrics and knitted fabrics, and JIS K 7130 for films.

[0040] In order to adjust the average domain size of the sheet, it is preferable to use an elastomeric resin with good compatibility, and it is also preferable to not only select such an elastomeric resin but also adjust the production conditions. For example, in a method of producing sheets of various shapes by melt-molding a mixture of two or more elastomeric resins, even if the domain size can be reduced by forming a compatible state through melt-kneading, there is a risk that the domains will grow during melt-molding, resulting in an increase in the domain size. Therefore, it is preferable to suppress the domain growth by rapid cooling.

[0041] For example, in a sheet made of fibers such as a nonwoven fabric, the domain size can be adjusted by adjusting the conditions for melt-spinning a mixture of two or more elastomeric resins and then quenching. For example, a sheet can be produced by a melt-blowing method, in which a molten mixture is discharged from a die, and a heated high-velocity airflow is directly blown onto the mixture through an airflow path built into the die, so that the fibrous discharged material is drawn out from the die together with the high-temperature high-velocity airflow and collected on a collecting surface to form a melt-blown nonwoven fabric.

[0042] The sheet manufacturing method may include a kneading step of melt-kneading a mixture of two or more elastomer resins to obtain an elastomer resin kneaded material, a discharge step of discharging the elastomer resin kneaded material together with air from a die, and a collection step of collecting the fibers discharged from the die on a collection surface to obtain a meltblown nonwoven fabric. The meltblowing method is preferable because it allows the discharged fibers to be rapidly cooled by applying an air flow to the fibers as they are discharged from the die and thinning them thereby, thereby enabling adjustment of the average domain size. In addition, in the meltblowing method, rapid cooling may be performed by applying cooling air directly below the spinning, in which case the cooling air may be at room temperature (e.g., about 10 to 40°C).

[0043] The mixture to be subjected to the kneading step may contain any of the above-mentioned elastomeric resins. In addition, the weight ratio of the elastomeric resin having the lowest glass transition temperature to the elastomeric resin having the highest glass transition temperature in the mixture to be subjected to the kneading step may be within the above-mentioned range.

[0044] The sheet has excellent vibration damping properties over a wide frequency range, and can therefore be used as a vibration damping sheet and as various soundproofing materials for sounds corresponding to the frequency range. Because the sheet can damp vibrations by converting vibration energy into thermal energy, the soundproofing material may be, for example, a laminate including the sheet as a sound absorbing layer, and the laminate may include a known sound insulating material as a sound insulating layer.

[0045] The soundproofing material can be used for vehicles, building materials, audio equipment, electronic devices, etc. In particular, it is preferable to use it in insulators for automobiles, as quietness is required due to the electrification of automobiles. For example, it can be used as a soundproofing material for components near the undercarriage of the vehicle body, such as fender liners, floor undercovers, and engine undercovers, as well as a soundproofing material for inner tires.

[0046] The present invention will be described in more detail below with reference to examples, but the present invention is not limited by these examples. In the following examples and comparative examples, various physical properties were measured by the following methods.

[0047] [Glass Transition Temperature of Elastomer Resin] The glass transition temperature of the elastomer resin was determined from the peak temperature of the curve obtained by measuring the temperature dependence of the loss factor tan δ using a solid dynamic viscoelasticity analyzer "Rheogel E-4000" manufactured by UBM Corp. in shear mode at a frequency of 1 Hz and a heating rate of 3°C / min. Here, the peak temperature of tan δ refers to the temperature at which the first derivative of the change in tan δ with respect to temperature becomes zero.

[0048] [Average domain size of the sheet] Using a scanning probe microscope (SPM; "E-sweep" manufactured by Hitachi High-Tech Science Corporation), a phase diagram was prepared from a cross section of the sheets obtained in the examples and comparative examples cut in a direction perpendicular to the sheet surface, the area of ​​each dispersed phase dispersed in the matrix was measured, and the diameter when each dispersed phase was considered to be a perfect circle having that area was calculated as the domain size. The measurement was performed on 30 dispersed phases, and the average value thereof was calculated as the average domain size.

[0049] [Basis Weight of Sheet] The basis weight of the sheet (g / m ２ ) was measured.

[0050] [Sheet Thickness] The sheet thickness (mm) was measured in accordance with 6.1 of JIS L 1913 "General nonwoven fabric testing methods."

[0051] [Apparent density of sheet] The apparent density of the sheet (g / cm ３) was calculated by dividing the basis weight measured above by the thickness.

[0052] [Air permeability] Air permeability (cm) was measured by the Frazier method in accordance with 6.8 of JIS L 1913 "General nonwoven fabric testing method." ３ / cm ２ s) was measured.

[0053] [Temperature Dependence of Loss Factor tan δ of Sheet] The sheets obtained in the Examples and Comparative Examples were cut into pieces 30 mm long and 5 mm wide to prepare test specimens. Using a solid-state dynamic viscoelasticity analyzer "Rheogel E-4000" manufactured by UBM Corporation, the temperature dependence of the loss factor tan δ of the test specimens was measured in tension mode at a frequency of 1 Hz, a heating rate of 3°C / min, and a temperature range of -50°C to 50°C. From the obtained temperature dependence curve of the loss factor tan δ, tan δ at 0°C, 20°C, and 40°C, the peak temperature of tan δ, the temperature range in which tan δ was 0.2 or greater, and the integral value in the temperature range from 0 to 40°C in which tan δ was 0.2 or greater were calculated.

[0054] Example 1 A hydrogenated copolymer having a polystyrene hard segment and a vinyl-polydiene soft segment, Tg=33°C, was used as the elastomeric resin A, and a hydrogenated copolymer having a polystyrene hard segment and a vinyl-polydiene soft segment, Tg=6°C, was used as the elastomeric resin B, which was dry-blended in a weight ratio of 50 / 50. The resulting mixture was discharged from a nozzle with a nozzle hole diameter of 0.3 mmφ at an extruder temperature of 220°C, a pipe temperature of 280°C, a die temperature of 320°C, and a single-hole discharge rate of 0.2 g / min·H, and immediately thereafter, hot air at 310°C was blown at a rate of 9.5 Nm per 1 m width. ３ The meltblown nonwoven fabric was produced by spraying the mixture at a rate of 1 / min to thin the fibers, and the die-to-collection distance (DCD) was set to 300 mm. The resulting meltblown nonwoven fabric had a basis weight of 66.1 g / m ２ , thickness 0.295 mm, breathability 21.0 cm ３ / cm ２ The obtained meltblown nonwoven fabric was subjected to dynamic viscoelasticity measurement, and a graph showing the temperature dependency of loss factor tan δ was obtained as shown in FIG.

[0055] [Example 2] A meltblown nonwoven fabric was produced under the same conditions as in Example 1, except that the same elastomer resin A and elastomer resin B as in Example 1 were dry blended in a weight ratio of 25 / 75. The obtained meltblown nonwoven fabric had a basis weight of 69.7 g / m ２ , thickness 0.251 mm, breathability 16.6 cm ３ / cm ２ The dynamic viscoelasticity of the obtained meltblown nonwoven fabric was measured, and a graph showing the temperature dependency of the loss factor tan δ was obtained as shown in FIG.

[0056] [Example 3] A meltblown nonwoven fabric was produced under the same conditions as in Example 1, except that the same elastomer resin A and elastomer resin B as in Example 1 were dry blended in a weight ratio of 10 / 90. The obtained meltblown nonwoven fabric had a basis weight of 70.4 g / m ２ , thickness 0.237 mm, breathability 13.6 cm ３ / cm ２ The obtained meltblown nonwoven fabric was subjected to dynamic viscoelasticity measurement, and a graph showing the temperature dependency of loss factor tan δ was obtained as shown in FIG.

[0057] [Example 4] A meltblown nonwoven fabric was produced under the same conditions as in Example 1, except that the same elastomer resin A as in Example 1 and a hydrogenated copolymer having a polystyrene hard segment and a vinyl-polydiene soft segment and a Tg of 14°C as elastomer resin B were dry-blended in a weight ratio of 50 / 50. The resulting meltblown nonwoven fabric had a basis weight of 64.6 g / m ２ , thickness 0.25 mm, breathability 28.6 cm ３ / cm ２ The obtained meltblown nonwoven fabric was subjected to dynamic viscoelasticity measurement, and a graph showing the temperature dependency of loss factor tan δ was obtained as shown in FIG.

[0058] Comparative Example 1 The same elastomer resin A and elastomer resin B as in Example 1 were dry-blended in a weight ratio of 50 / 50. The resulting mixture was hot-pressed at a molding temperature of 240°C for 3 minutes to obtain a film sample. The thickness of the obtained film was 1.021 mm. Dynamic viscoelasticity measurement of the obtained film yielded a graph of the temperature dependence of loss factor tan δ as shown in Figure 5.

[0059]

[0060] As shown in Table 1, the sheets of Examples 1 to 4 have small average domain sizes within a specific range, and therefore have high integral values ​​in the range where tan δ is 0.2 or more in the temperature range of 0 to 40°C, and have excellent vibration damping properties over a wide frequency range. Furthermore, the temperature dependence curves of tan δ for the sheets of Examples 1 to 4 show a single peak, and the temperature range where tan δ is 0.2 or more is wide.

[0061] On the other hand, the sheet of Comparative Example 1 has a large average domain size, and therefore, compared with Examples 1 to 4, the integrated value in the range where tan δ is 0.2 or more in the temperature range of 0 to 40°C is low.

[0062] Because the sheet has excellent vibration damping properties over a wide frequency range, it can be used as a vibration damping sheet and as a soundproofing material for various types of sound corresponding to that frequency range. The soundproofing material can be used for vehicles, building materials, audio equipment, electronic equipment, etc.

[0063] As described above, the preferred embodiments of the present invention have been described, but various additions, modifications, or deletions can be made without departing from the spirit of the present invention, and such additions, modifications, or deletions are also included within the scope of the present invention.

Claims

1. A sheet containing two or more types of elastomeric resins, wherein domains exist in the sheet, the average domain size is 5 μm or less, and the domains are components derived from the elastomeric resins.

2. The sheet according to claim 1, wherein the two or more types of elastomer resins are both copolymers having a polystyrene-based hard segment and a vinyl-polydiene-based soft segment, or hydrogenated copolymers thereof.

3. The sheet according to claim 1 or 2, wherein the glass transition temperature Tg of the elastomer resin having the highest glass transition temperature among the elastomer resins is 1. Ｈ and the glass transition temperature Tg of the elastomer resin having the lowest glass transition temperature Ｌ The difference between the temperature and the sheet temperature is 5 to 60°C.

4. A sheet according to claim 1 or 2, wherein the weight percentage of the elastomer resin having the lowest glass transition temperature among the elastomer resins is equal to or greater than the weight percentage of the elastomer resin having the highest glass transition temperature.

5. The sheet according to claim 1 or 2, wherein the peak temperature of the loss factor tanδ calculated by dynamic viscoelasticity measurement is within the range of 0 to 40°C.

6. A sheet according to claim 1 or 2, wherein in a temperature dependency curve of loss factor tanδ obtained by dynamic viscoelasticity measurement, the integral value in the range of loss factor tanδ of 0.2 or more in the temperature range of 0 to 40°C is 25 or more.

7. A sheet according to claim 1 or 2, which is a nonwoven fabric.

8. The sheet according to claim 7, which is a long-fiber nonwoven fabric.

9. The sheet according to claim 1 or 2, having an apparent density of 0.10 g / cm ３ That's it, sheet.

10. The sheet according to claim 1 or 2, having an air permeability of 100 cm ３ / cm ２ ・A sheet that is less than or equal to s.

11. A soundproofing material comprising the sheet according to claim 1 or 2.

12. The soundproofing material according to claim 11, which is for vehicles, buildings, or acoustic equipment.

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