JP7742696B2 - thermoplastic resin composition - Google Patents

Description

The present invention relates to a thermoplastic resin composition and a method for producing the same. More specifically, the present invention relates to a thermoplastic resin composition that can be used as a vibration-damping material in acoustic equipment, electrical appliances, vehicles, buildings, industrial equipment, etc., a method for producing the same, an additive that imparts vibration-damping properties to the resin composition, and a vibration-damping material containing the thermoplastic resin composition.

In recent years, there has been a growing demand for vibration control measures for various types of equipment, particularly in fields such as automobiles, home appliances, and precision instruments. Generally, highly vibration-damping materials include composite materials such as metal plates bonded together with vibration-absorbing materials like rubber or asphalt, or vibration-damping steel plates, which sandwich a vibration-absorbing material between metal plates. These vibration-damping materials maintain their shape with highly rigid metal plates and absorb vibrations with the vibration-absorbing material. Metal-only alloy materials also exist, which use twin crystals or ferromagnetism to convert kinetic energy into thermal energy and absorb vibrations. However, composite materials have limitations in formability due to the bonding of different materials, and the use of metal steel plates results in heavy products. Furthermore, alloy materials are heavy because they are made solely of metal, and their vibration-damping performance is insufficient.

In response to this conventional technology, functional resin compositions with vibration-damping properties have been proposed. For example, Patent Document 1 discloses a vibration-damping molded resin product made from a polypropylene-based resin composition in which a reinforcing inorganic filler is blended with a resin component in which high-density polyethylene (HDPE) and an aromatic hydrocarbon resin are added and mixed with crystalline polypropylene (PP), and the resin composition is characterized in that a hydrogenated product of an aromatic vinyl-conjugated diene block copolymer is further added and mixed as a resin component.

Japanese Patent Application Publication No. 5-331329

However, while the polypropylene resin composition of Patent Document 1 improves vibration damping at room temperature, the improvement in vibration damping at high temperatures is small.

The present invention relates to a thermoplastic resin composition that exhibits excellent vibration-damping properties over a wide temperature range, a method for producing the same, an additive for the resin composition, and a vibration-damping material containing the thermoplastic resin composition.

The present invention relates to the following [1] to [4].
[1] A thermoplastic resin composition comprising a thermoplastic resin, an elastomer having a polar functional group, and a filler, wherein the glass transition temperature of the elastomer having a polar functional group is −20° C. or higher and 80° C. or lower.
[2] A method for producing a thermoplastic resin composition, comprising a step of melt-kneading a thermoplastic resin with an additive containing a melt-kneaded mixture of an elastomer having a polar functional group and a filler, wherein the glass transition temperature of the elastomer having a polar functional group is −20° C. or higher and 80° C. or lower.
[3] An additive comprising a melt-kneaded mixture of an elastomer having a polar functional group and a filler, wherein the glass transition temperature of the elastomer having a polar functional group is −20° C. or higher and 80° C. or lower.
[4] A vibration-damping material comprising the thermoplastic resin composition according to [1] or the additive according to [3].

The present invention provides a thermoplastic resin composition with excellent vibration-damping properties, a method for producing the same, an additive for the resin composition, and a vibration-damping material containing the thermoplastic resin composition.

The inventors have newly discovered that the vibration-damping properties of a thermoplastic resin composition can be improved by creating some kind of chemical bond between the elastomer and filler added to the thermoplastic resin composition and strengthening the interface between them. While the mechanism behind this is unclear, it is presumed that strengthening the interface between the elastomer and filler increases the strain energy in the elastomer.

The thermoplastic resin composition of the present invention contains a thermoplastic resin, an elastomer having a polar functional group, and a filler.

[Thermoplastic resin]
The thermoplastic resin used in the present invention is not particularly limited, and examples include polyolefin resin, polyamide resin, polystyrene resin, vinyl chloride resin, ABS resin, acrylic resin, polyester resin, etc., and from the viewpoint of use as a structural material, it is preferably one or more types selected from the group consisting of polyolefin resin and polyamide resin, more preferably one or more types selected from polypropylene and nylon, even more preferably one or more types selected from polyolefin and polylactam, even more preferably one or more types selected from polypropylene and nylon 6, and even more preferably polypropylene or nylon 6. From the same viewpoint, the weight average molecular weight of the thermoplastic resin used in the present invention is preferably 1,000 to 1,000,000.

From the viewpoint of obtaining a vibration-damping material, the amount of thermoplastic resin in the thermoplastic resin composition of the present invention is preferably 30% by mass or more, more preferably 50% by mass or more, and even more preferably 70% by mass or more. On the other hand, from the viewpoint of obtaining a molded article or vibration-damping material that exhibits the desired vibration-damping properties, the amount is preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 75% by mass or less.

[Elastomer having polar functional group]
The glass transition temperature (Tg) of the polar functional group-containing elastomer is -20°C or higher, preferably -15°C or higher, and more preferably -10°C or higher, from the viewpoint of improving vibration damping properties in both high and low temperature ranges. From the same viewpoint, it is 80°C or lower, preferably 40°C or lower, and more preferably 10°C or lower. In this specification, the high temperature range refers to 35 to 80°C, and the low temperature range refers to -20 to 10°C. The polar functional group of the polar functional group-containing elastomer is not particularly limited as long as it can bond to the filler. Examples include ester groups, amide groups, hydroxyl groups, carboxy groups, amino groups, acid anhydride groups, epoxy groups, and carbodiimide groups. From the viewpoint of reactivity, acid anhydride groups are preferred, and maleic anhydride groups are more preferred. One or more polar functional groups can be introduced. Examples of such elastomers include maleic anhydride-modified polystyrene-hydrogenated polybutadiene copolymer (SEBS), maleic anhydride-modified polystyrene-isobutylene-polystyrene block copolymer (SIBS), epoxy-modified polystyrene-hydrogenated polybutadiene copolymer (SEBS), polylactic acid (PLA), maleic anhydride-modified polylactic acid (PLA), etc., and from the viewpoint of improving vibration damping properties, maleic anhydride-modified polystyrene-hydrogenated polybutadiene copolymer (SEBS) and maleic anhydride-modified polylactic acid (PLA) are preferred. One or more types of elastomers having a polar functional group can be used.

In the thermoplastic resin composition of the present invention, the amount of elastomer having a polar functional group is, from the viewpoint of improving vibration damping, preferably 5 parts by mass or more, more preferably 8 parts by mass or more, even more preferably 10 parts by mass or more, and even more preferably 15 parts by mass or more, per 100 parts by mass of thermoplastic resin; and from the same viewpoint, it is preferably 60 parts by mass or less, more preferably 40 parts by mass or less, even more preferably 35 parts by mass or less, even more preferably 30 parts by mass or less, and even more preferably 20 parts by mass or less. When two or more elastomers having a polar functional group are contained, the amount is the total amount of these.

The amount of polar functional group added is not particularly limited and can be selected appropriately depending on the type of polar functional group and elastomer. For example, in embodiments where the elastomer having a polar functional group is maleic anhydride-modified polystyrene-hydrogenated polybutadiene copolymer (SEBS) or maleic anhydride-modified polylactic acid (PLA), from the viewpoint of improving vibration damping, the amount is preferably 0.1 parts by mass or more, more preferably 0.2 parts by mass or more, and even more preferably 0.25 parts by mass or more, per 100 parts by mass of the elastomer before addition. From the same viewpoint, the amount is preferably 10 parts by mass or less, more preferably 1 part by mass or less, even more preferably 0.8 parts by mass or less, and even more preferably 0.3 parts by mass or less. The amount of maleic anhydride added in this embodiment can be measured by acid value titration.

The elastomer having a polar functional group can be a thermoplastic elastomer known as a vibration-damping elastomer. From the perspective of improving vibration-damping properties in high and low temperature ranges, the thermoplastic elastomer preferably has a glass transition temperature Tg of -40°C or higher and preferably 80°C or lower. Furthermore, the peak value of tan δ obtained from viscoelasticity measurements of the elastomer is preferably 0.5 or higher, more preferably 0.8 or higher, and even more preferably 1.0 or higher. The temperature range in which tan δ is 0.5 or higher is preferably 10°C or higher, more preferably 20°C or higher. From the perspective of improving vibration-damping properties in high and low temperature ranges, the temperature range in which tan δ is 0.5 or higher is preferably -40°C to 80°C. The thermoplastic elastomer is preferably one or more selected from, for example, styrene-based thermoplastic elastomers, olefin-based thermoplastic elastomers, polyester-based thermoplastic elastomers, polyamide-based thermoplastic elastomers, urethane-based thermoplastic elastomers, nitrile-based thermoplastic elastomers, fluorine-based thermoplastic elastomers, polybutadiene-based thermoplastic elastomers, and silicone-based thermoplastic elastomers, and from the viewpoint of improving vibration damping properties in high and low temperature ranges, styrene-based thermoplastic elastomers are preferred.

Styrenic thermoplastic elastomers (hereinafter sometimes referred to as styrene elastomers) consist of block A, which is formed by polymerizing a styrene compound constituting the hard segment, and block B, which is formed by polymerizing a conjugated diene constituting the soft segment. Examples of styrene compounds used in block A include styrene, α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, and 1,3-dimethylstyrene, with styrene being more preferred. Examples of conjugated dienes used in polymer block B include butadiene, isoprene, 1,3-pentadiene, and 2,3-dimethyl-1,3-butadiene, with butadiene being preferred. Block A is a polymer of one or more styrene compounds, preferably a polymer of styrene. Block B is a block polymer of one or more conjugated diene monomers, preferably a copolymer of butadiene. Block A may be copolymerized with the conjugated diene used in polymer block B. Block B may also be copolymerized with the styrene-based compound used in polymer block A. Each copolymer may be in the form of a random copolymer, a block copolymer, or a tapered copolymer. It may also have a hydrogenated structure.

Specific examples of such styrene-based elastomers include polystyrene-isoprene block copolymer (SIS), polystyrene-polybutadiene copolymer (SBS), polystyrene-hydrogenated polybutadiene copolymer (SEBS), polystyrene-hydrogenated polyisoprene-polystyrene block copolymer (SEPS), polystyrene-vinyl-polyisoprene-polystyrene block copolymer (SHIVS), polystyrene-isobutylene-polystyrene block copolymer (SIBS), polystyrene-ethylene-butylene-polyolefin (preferably polypropylene) block copolymer (SEBC), polystyrene-hydrogenated polybutadiene-hydrogenated polyisoprene-polystyrene block copolymer, and polystyrene-hydrogenated polybutadiene-polyisoprene-polystyrene block copolymer. These may be used alone or in combination of two or more. Among these, SEBS is preferred in the present invention.

A styrene-based elastomer having a Tg of -20°C or higher and 80°C or lower is one in which the Tg of the soft segment is -20°C or higher and 80°C or lower, and the Tg of the soft segment can be controlled by selecting the monomer. The soft segment may be in the form of a random copolymer, a block copolymer, or a tapered copolymer. In the present invention, the amount of the soft segment is preferably such that the theoretical glass transition temperature (Tg) of the copolymer calculated according to the Fox formula is in the range of -20°C to 80°C. For example, a composition in which the soft segment is a random copolymer of butadiene and styrene, such as S.O.E. S1605 (butadiene 33% by mass, styrene 37% by mass), can be mentioned. In the case of S1605, the styrene content is preferably 20% by mass or higher, more preferably 29% by mass or higher, and preferably 92% by mass or lower, more preferably 72% by mass or lower, calculated assuming that the Tg of butadiene is -50°C and the Tg of styrene is 100°C. Furthermore, in the case of soft segments made of diene block copolymers, when the molecular structure is branched rather than linear, rotational motion is more inhibited and Tg shifts to a higher temperature. For example, in the case of butadiene, the Tg can be increased because the side chain is longer and less likely to rotate in the 1,2-addition than in the 1,4-addition. In addition, the higher the molecular mobility of the monomer used in the soft segment, the lower the Tg shifts. The Fox formula is the following relationship for the glass transition temperature (Tg) of a copolymer:
1/Tg=Σ(Wi/Tgi) (where Wi is the weight fraction of monomer i, and Tgi is the Tg of the homopolymer of monomer i.)

Elastomers having polar functional groups can be prepared by directly reacting the polar functional groups with the elastomer, by introducing a polymer having polar functional groups through copolymerization, or by mixing with a component having polar functional groups. However, direct reaction of the polar functional groups is preferred. Furthermore, from the perspective of vibration damping and impact resistance, it is preferable to remove residual monomers. Methods for removing residual monomers include washing with an organic solvent, vent suction, and vaporization, with washing with an organic solvent being preferred.

[Filler]
The filler is not particularly limited as long as it is a known filler having a polar functional group, and examples thereof include inorganic fillers, cellulose, etc. In the present invention, one or more fillers can be used.

[Inorganic filler]
The inorganic filler is not particularly limited as long as it is a known inorganic filler having a polar functional group, and among the polar functional groups, a reactive functional group that bonds with an elastomer having a polar functional group is preferred. Furthermore, inorganic fillers having a reactive functional group include plate-like fillers, granular fillers, needle-like fillers, fibrous fillers, etc., and plate-like fillers are preferred.

Bonding with an elastomer means some kind of chemical bond. Examples include hydrogen bonds, ionic bonds, and covalent bonds. Stronger bonds are preferable, with covalent bonds being more preferred.

Reactive functional groups include hydroxyl groups and amino groups, with hydroxyl groups being preferred and silanol groups being more preferred.

Inorganic fillers having such reactive functional groups include metal oxides, metal oxide salts, metal hydroxides, and metal carbonates, preferably one or more selected from the group consisting of metal oxides and metal oxide salts, more preferably silicates, more preferably one or more selected from the group consisting of silicate minerals and glass fibers, and even more preferably mica.

In order to strengthen the interaction between the elastomer and the inorganic filler, the particle size of the inorganic filler may be reduced, thereby increasing the interfacial adhesive surface area.

[cellulose]
The cellulose is not particularly limited, and examples thereof include woody plants (coniferous and broad-leaved trees), herbaceous plants (plant materials from the Poaceae, Malvaceae, and Leguminosae families, and non-woody materials from palm plants), pulps (such as cotton linter pulp obtained from the fibers surrounding cotton seeds), and papers (newspapers, cardboard, magazines, and fine paper). Among these, woody and herbaceous plants are preferred from the viewpoints of availability and cost reduction. The average fiber diameter of the cellulose-based raw material is not particularly limited, but from the viewpoints of availability and cost reduction, it is preferably 5 μm or more, more preferably 7 μm or more, and even more preferably 15 μm or more. From the same viewpoint, it is preferably 500 μm or less, more preferably 100 μm or less, and even more preferably 30 μm or less. Cellulose may be used as is, or may be modified by reacting the hydroxyl groups of cellulose with an ether compound, alkyl chloride, alkyl acid anhydride, alkyl acid chloride, or the like, or may be used after reducing the crystallinity. Cellulose obtained by reacting hydroxyl groups of cellulose with an ether compound, alkyl chloride, alkyl acid anhydride, alkyl acid chloride, etc. is sometimes called modified cellulose. Cellulose with reduced crystallinity is sometimes called decrystallized cellulose. Cellulose used as is is sometimes called unmodified cellulose. In the present invention, one or more types of cellulose selected from the group consisting of unmodified cellulose, modified cellulose, and decrystallized cellulose can be used.

There are no particular limitations on the cellulose, as long as it has a polar functional group. Of the polar functional groups, those with reactive functional groups that bond with elastomers that have polar functional groups are preferred. Bonding with an elastomer refers to some kind of chemical bond. Examples include hydrogen bonds, ionic bonds, and covalent bonds. Stronger bonds are preferred, with covalent bonds being more preferred. Reactive functional groups on cellulose include hydroxyl groups in unmodified cellulose, and hydroxyl groups, carboxyl groups, amino groups, and quaternary ammonium groups in modified cellulose.

In the thermoplastic resin composition of the present invention, the amount of filler is preferably 1 part by mass or more, more preferably 10 parts by mass or more, and even more preferably 14 parts by mass or more, per 100 parts by mass of the thermoplastic resin, from the viewpoint of improving the strength of the thermoplastic resin composition; and is preferably 70 parts by mass or less, more preferably 60 parts by mass or less, even more preferably 50 parts by mass or less, even more preferably 40 parts by mass or less, and even more preferably 25 parts by mass or less, from the viewpoint of suppressing a decrease in vibration damping properties. Furthermore, in the thermoplastic resin composition of the present invention, the amount of filler is preferably 90 parts by mass or more, more preferably 120 parts by mass or more, and even more preferably 130 parts by mass or more, per 100 parts by mass of the elastomer having a polar functional group, from the viewpoint of suppressing a decrease in vibration damping properties; and from the same viewpoint, is preferably 200 parts by mass or less, more preferably 150 parts by mass or less, and even more preferably 140 parts by mass or less. When two or more fillers are used, the amount is the total amount of the fillers.

[Optional ingredients]
The thermoplastic resin composition of the present invention may contain, as other components than those described above, chain extenders, plasticizers, organic crystal nucleating agents, inorganic crystal nucleating agents, hydrolysis inhibitors, flame retardants, antioxidants, lubricants such as hydrocarbon waxes and anionic surfactants, ultraviolet absorbers, antistatic agents, antifogging agents, light stabilizers, pigments, mildew inhibitors, antibacterial agents, foaming agents, etc. Similarly, the thermoplastic resin composition of the present invention may contain other polymeric materials or other resin compositions within the range of not impairing the effects of the present invention.

[Example of a method for producing a thermoplastic resin composition]
A specific example of a method for producing a thermoplastic resin composition of the present invention includes a step of melt-kneading a thermoplastic resin with an additive containing a melt-kneaded mixture of an elastomer having a polar functional group and a filler. The additive may be prepared separately, but the production process for the thermoplastic resin composition may further include a step of melt-kneading a mixture of an elastomer having a polar functional group and a filler, and the resulting kneaded mixture may be used as the additive. Melt-kneading can be performed using a known kneading machine, such as an internal kneader, a single-screw or twin-screw extruder, or an open-roll kneader. After melt-kneading, the melt-kneaded mixture may be dried or cooled according to a known method. Alternatively, the raw materials may be uniformly mixed in advance using a Henschel mixer, a super mixer, or the like, before being subjected to melt-kneading.

The preferred ratio of the elastomer having a polar functional group to the filler, and the preferred ratio of the additive to the thermoplastic resin, can be calculated based on the numerical ranges described above for the thermoplastic resin of the present invention.

[Additives]
The additive of the present invention includes a melt-kneaded mixture of an elastomer having a polar functional group and a filler. In addition to the melt-kneaded mixture, the additive may optionally contain chain extenders, plasticizers, organic crystal nucleating agents, inorganic crystal nucleating agents, hydrolysis inhibitors, flame retardants, antioxidants, lubricants such as hydrocarbon waxes and anionic surfactants, UV absorbers, antistatic agents, antifogging agents, light stabilizers, pigments, mildew inhibitors, antibacterial agents, and foaming agents, as long as the effects of the present invention are not impaired. Furthermore, the additive of the present invention may contain a portion of the resin (e.g., 0.1 to 50.0% by mass of the additive) that is melt-kneaded with the additive. The additive of the present invention can be used as an additive for various resins.

Resins to which the additive of the present invention can be added include, for example, polyolefin resins, polyamide resins, polystyrene resins, vinyl chloride resins, ABS resins, acrylic resins, and polyester resins. From the viewpoint of improving the vibration-damping properties of thermoplastic resin compositions, the additive is preferably one or more resins selected from the group consisting of polyolefin resins and polyamide resins, more preferably one or more resins selected from polypropylene and nylon, even more preferably one or more resins selected from polyolefins and polylactams, even more preferably one or more resins selected from polypropylene and nylon 6, and even more preferably polypropylene or nylon 6. As described above, such additives can improve the vibration-damping properties of thermoplastic resin compositions by melt-kneading with the various thermoplastic resins described above.

From the viewpoint of improving vibration damping properties, the content of the elastomer having a polar functional group in the additive is preferably 10% by mass or more, more preferably 30% by mass or more, and even more preferably 40% by mass or more. From the same viewpoint, it is preferably 55% by mass or less, more preferably 50% by mass or less, and even more preferably 45% by mass or less. From the viewpoint of improving vibration damping properties, the content of the filler in the additive is preferably 30% by mass or more, more preferably 50% by mass or more, and even more preferably 55% by mass or more. From the same viewpoint, it is preferably 90% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less. One preferred embodiment of the additive of the present invention consists of an elastomer having a polar functional group and a filler.

Elastomers having polar functional groups may contain unreacted substances to which the polar functional groups have been added. From the perspective of improving the effects of the present application, it is preferable to remove these unreacted substances. Preferred methods for removal include solvent washing and evaporation, with solvent washing being particularly preferred, and acetone washing being even more preferred.

The additives and the melt-kneading temperature and time used to prepare the thermoplastic resin composition are not set in stone depending on the types of raw materials used, but are preferably 170 to 240°C and 15 to 900 seconds.

The thermoplastic resin composition of the present invention can be suitably used as a vibration-damping material for products such as acoustic equipment, electrical appliances, buildings, industrial equipment, automotive components, motorcycle components, containers, or their parts or housings by using various molding and processing methods such as injection molding, extrusion molding, and thermoforming.

For example, when manufacturing a part or housing containing the thermoplastic resin composition of the present invention by injection molding, pellets of the thermoplastic resin composition or an additive containing the thermoplastic resin composition are filled into an injection molding machine and then injected into a mold for molding.

For injection molding, a known injection molding machine can be used. For example, one having a cylinder and a screw inserted therein as its main components (J75E-D, J110AD-180H (manufactured by The Japan Steel Works, Ltd.), etc.) can be used. While the raw materials for the thermoplastic resin composition may be supplied to the cylinder and melt-kneaded directly, it is preferable to melt-knead the materials in advance and then charge them into the injection molding machine.

In addition, when using a molding method other than injection molding, it is sufficient to use a known molding method, and there are no particular limitations.

Molded articles made from the thermoplastic resin composition of the present invention can be suitably used as vibration-damping materials for products such as acoustic equipment, electrical appliances, buildings, industrial equipment, automobile parts, motorcycle parts, containers, or their parts or housings.

The present invention will be explained in detail below using examples, but the present invention is not limited to these examples. Note that "normal pressure" refers to 101.3 kPa.

[Preparation Example 1 of Elastomer Having Polar Functional Group]
Using a co-rotating intermeshing twin-screw extruder (TEX-28V, manufactured by The Japan Steel Works, Ltd., L/D = 42, D = 28), 100 parts by mass of SEBS (trade name: SOE S1605, manufactured by Asahi Kasei Chemicals Corporation), 6.0 parts by mass of maleic anhydride (trade name: Maleic Anhydride, manufactured by Wako Pure Chemical Industries, Ltd.), and 0.1 parts by mass of the organic peroxide dicumyl peroxide (trade name: Percumyl D, manufactured by NOF Corporation) were reactively mixed at 260 °C and strand cut to obtain pellets of maleic anhydride-modified SEBS. The resulting pellets were dehumidified and dried at 80 °C under atmospheric pressure for 3 hours to reduce the moisture content to 1000 ppm or less. The resulting pellets were then washed with refluxing acetone for 3 hours to remove residual monomer. The amount of maleic anhydride added was measured by acid value titration and found to be 0.28 parts by mass. The amount of maleic anhydride added is a value relative to 100 parts by mass of SEBS. The glass transition temperature was 3°C.

[Preparation Example 2 of Elastomer Having Polar Functional Group]
The same procedure as in Preparation Example 1 of Elastomer Having Polar Functional Groups was carried out, except that PLA was used instead of SEBS. The amount of maleic anhydride added was measured by acid value titration and found to be 0.74 parts by mass. The amount of maleic anhydride added is a value relative to 100 parts by mass of PLA. The glass transition temperature was 50°C.

Example 1
Using a co-rotating intermeshing twin-screw extruder (TEX-28V, manufactured by The Japan Steel Works, Ltd., L/D=42, D=28), the pellets obtained in Preparation Example 1 as the elastomer, mica as a filler, and nylon 6 as the thermoplastic resin were melt-kneaded at 240°C and strand-cut to obtain pellets of a thermoplastic resin composition. The obtained pellets were dehumidified and dried at 110°C under normal pressure for 3 hours to reduce the moisture content to 500 ppm or less.

Comparative Examples 1 and 2
Pellets of a thermoplastic resin composition were obtained in the same manner as in Example 1, except that the elastomers shown in Table 1 were used.

Example 2
Using a co-rotating intermeshing twin-screw extruder (TEX-28V, manufactured by The Japan Steel Works, Ltd., L/D=42, D=28), the pellets obtained in Preparation Example 1 as the elastomer, mica as a filler, and a polypropylene resin as the thermoplastic resin were melt-kneaded at 200°C and strand-cut to obtain pellets of a thermoplastic resin composition. The obtained pellets were dehumidified and dried at 110°C under normal pressure for 3 hours to reduce the moisture content to 500 ppm or less.

Examples 3 to 6, Comparative Examples 3 to 7
Pellets of a thermoplastic resin composition were obtained in the same manner as in Example 2, except that the raw materials shown in Tables 1 to 3 were used.

The pellets obtained in Example 1 and Comparative Examples 1 and 2 were injection molded using an injection molding machine (Japan Steel Works, Ltd. J110AD-180H, cylinder temperature settings at six locations). The cylinder temperatures were set to 240°C for the first five units from the nozzle tip, 170°C for the remaining unit, and 45°C below the hopper. The mold temperature was set to 80°C, and rectangular prism test pieces (127 mm x 12.7 mm x 1.6 mm) were molded to obtain molded bodies of the resin composition. The resulting molded bodies were subjected to the various evaluation tests.

The pellets obtained in Examples 2 to 6 and Comparative Examples 3 to 7 were injection molded using an injection molding machine (Japan Steel Works, Ltd. J110AD-180H, cylinder temperature settings at six locations). The cylinder temperatures were set to 200°C for the first five units from the nozzle tip, 170°C for the remaining unit, and 45°C below the hopper. The mold temperature was set to 80°C, and rectangular prism test pieces (127 mm x 12.7 mm x 1.6 mm) were molded to obtain molded bodies of the resin composition. The resulting molded bodies were subjected to the various evaluation tests.

<Loss coefficient>
For a rectangular prism test piece (127 mm x 12.7 mm x 1.6 mm), the loss factor was calculated using the half-width method from the secondary resonance peak of the frequency response function measured using the central excitation method based on JIS K7391. A system consisting of a Type 3160 oscillator, a Type 2718 amplifier, a Type 4810 vibrator, and a Type 8001 acceleration sensor (all manufactured by B&K) was used, and loss factor measurement software MS18143 was used. The measurement environment was controlled by a thermostatic chamber (PU-3J manufactured by Espec Corporation), and measurements were made over a temperature range from 0°C to 80°C. Tables 1 to 3 show the results at 20°C, 30°C, and 40°C for Examples 1, 2, and 5 and Comparative Examples 1 to 5, the results at 60°C, 70°C, and 80°C for Examples 3 and 4, and the results at 20°C, 50°C, and 70°C for Example 6 and Comparative Examples 6 and 7.

<Glass transition temperature>
Measurement was performed according to the method of JIS K 7121. Using a differential scanning calorimeter (DSC7020 manufactured by Hitachi High-Tech Science), the temperature was raised from -60°C to 200°C at a rate of 10°C/min, and the heat capacity was measured. The midpoint glass transition temperature Tmg (°C) was determined as the temperature at the point in the DSC thermogram where a line equidistant in the vertical direction from the line extending each baseline intersects with the curve representing the stepwise change in the glass transition.

<Water content>
Measurement was carried out according to the method of JIS K 7251-B. Using a coulometric Karl Fischer moisture meter (Mitsubishi Analytech Co., Ltd., CA-200) and an automatic moisture vaporizer (Mitsubishi Analytech Co., Ltd., VA-236S), a test was carried out at a heating temperature of 150°C, with two points per sample, and the moisture content was measured by the moisture vaporization method.

Details of each component shown in Tables 1 to 3 are as follows.
6 Nylon Amilan: (Product name: CM1017, manufactured by Toray Industries, Inc.)
Polypropylene resin: (product name: BC03B, manufactured by Japan Polypropylene Corporation)
SEBS: (trade name: SOE S1605, glass transition temperature 7°C, manufactured by Asahi Kasei Chemicals Corporation)
Maleic anhydride-modified SEBS: (trade name: Tuftec M1943, glass transition temperature -40°C, manufactured by Asahi Kasei Chemicals Corporation)
PLA: (product name: 4060D, glass transition temperature 57°C, manufactured by Nature Works)
Mica: (Product name: A-21S, manufactured by Yamaguchi Mica Co., Ltd.)
Silica: (product name: E-743, manufactured by Tosoh Silica Corporation)
Crystalline cellulose fiber: (KC Flock W-50GK, manufactured by Nippon Paper Industries Co., Ltd.)

Tables 1 to 3 show that the thermoplastic resin compositions of Examples 1, 2, 5, and 6 all have superior vibration-damping properties compared to Comparative Examples 1, 3, 5, and 6, which added SEBS, which does not have polar functional groups, as an elastomer. They also have superior vibration-damping properties compared to the thermoplastic resin compositions of Comparative Examples 2, 4, and 7, which added maleic anhydride-modified SEBS, which has polar functional groups but a glass transition temperature of -40°C. Furthermore, the thermoplastic resin composition of Example 4, which used PLA as an elastomer with polar functional groups, also had excellent vibration-damping properties, but Example 3, which used maleic anhydride-modified PLA, had even better vibration-damping properties.

The thermoplastic resin composition of the present invention can be suitably used in products such as audio equipment, electrical appliances, buildings, industrial equipment, automobile parts, motorcycle parts, and containers.

Claims (12)

A thermoplastic resin composition comprising a thermoplastic resin, an elastomer having a polar functional group, and a filler having a reactive functional group that bonds with the elastomer having a polar functional group, wherein the glass transition temperature of the elastomer having a polar functional group is -15°C or higher and 50°C or lower, and the amount of the elastomer having a polar functional group blended per 100 parts by mass of the thermoplastic resin is 5 parts by mass or higher and 60 parts by mass or lower. The thermoplastic resin composition according to claim 1, wherein the glass transition temperature of the elastomer having a polar functional group is -15°C or higher and 40°C or lower. The thermoplastic resin composition according to claim 1 or 2, wherein the amount of filler blended in the thermoplastic resin composition is 1 part by mass or more and 70 parts by mass or less per 100 parts by mass of the thermoplastic resin. The thermoplastic resin composition according to any one of claims 1 to 3, wherein the amount of filler blended in the thermoplastic resin composition is 100 parts by mass or more and 200 parts by mass or less per 100 parts by mass of the elastomer having a polar functional group. The thermoplastic resin composition according to any one of claims 1 to 4, wherein the amount of thermoplastic resin in the thermoplastic resin composition is 30% by mass or more and 90% by mass or less. The thermoplastic resin composition according to any one of claims 1 to 5, wherein the polar functional group of the elastomer having a polar functional group is an acid anhydride group. A method for producing a thermoplastic resin composition, comprising the step of melt-kneading a thermoplastic resin with an additive comprising a melt-kneaded mixture of an elastomer having a polar functional group and a filler having a reactive functional group that bonds to the elastomer having a polar functional group, wherein the glass transition temperature of the elastomer having a polar functional group is -15°C or higher and 50°C or lower, and the amount of the elastomer having a polar functional group blended per 100 parts by mass of the thermoplastic resin is 5 parts by mass or higher and 60 parts by mass or lower. The method for producing a thermoplastic resin composition according to claim 7, further comprising a step of melt-kneading a mixture of an elastomer having a polar functional group and a filler, and using the resulting kneaded mixture as the additive. The method for producing a thermoplastic resin composition according to claim 7 or 8, wherein the polar functional group is an acid anhydride group. A vibration-damping material comprising the thermoplastic resin composition described in any one of claims 1 to 6. A thermoplastic resin composition comprising a thermoplastic resin, an elastomer having a polar functional group, and a filler, wherein the glass transition temperature of the elastomer having the polar functional group is −15° C. or higher and 50° C. or lower, the polar functional group is an acid anhydride group, the blending amount of the elastomer having the polar functional group is 5 parts by mass or higher and 60 parts by mass or lower per 100 parts by mass of the thermoplastic resin, and the filler is bonded to the elastomer having the polar functional group by a hydrogen bond, an ionic bond, or a covalent bond . 12. A method for producing a thermoplastic resin composition according to claim 11, comprising a step of melt-kneading a thermoplastic resin with an additive including a melt-kneaded mixture of an elastomer having a polar functional group and a filler, wherein the elastomer having a polar functional group has a glass transition temperature of −15° C. or higher and 50° C. or lower, the polar functional group is an acid anhydride group, and the blending amount of the elastomer having a polar functional group per 100 parts by mass of the thermoplastic resin is 5 parts by mass or higher and 60 parts by mass or lower.