JP-2026075295-A - Magnetic field-responsive elastomer composition

Abstract

[Problem] To provide a composition that forms a magnetic field-responsive resin material in which the elastic modulus changes significantly in response to the application of a magnetic field, and which responds immediately to the application of a magnetic field, causing the elastic modulus to change rapidly. [Solution] The magnetic field-responsive elastomer composition of the present invention comprises an organopolysiloxane resin (A) and a soft magnetic filler (B), wherein the organopolysiloxane resin (A) has a complex shear modulus of elasticity at a frequency of 1 Hz (according to JIS K7244-10, 25°C) of 2,500 to 50,000 Pa, and the soft magnetic filler (B) is a soft magnetic material with a saturation magnetic flux density of 900 mT or more, and the content of the soft magnetic filler (B) is 30% or more and less than 60% by volume of the total composition. [Selection Diagram] None

Inventors

• 小川 昂実
• 三俣 哲
• 川合 巳佳
• 渡邊 開仁
• 金森 廉太郎

Assignees

• 株式会社タイカ
• 国立大学法人 新潟大学

Dates

Publication Date

20260508

Application Date

20241022

Claims (8)

1. A magnetic field-responsive elastomer composition comprising an organopolysiloxane resin (A) and a soft magnetic filler (B), The organopolysiloxane resin (A) has a complex shear modulus of elasticity at a frequency of 1 Hz (according to JIS K7244-10, 25°C) of 2,500 to 50,000 Pa of the cured resin. The soft magnetic filler (B) is a soft magnetic material with a saturation magnetic flux density of 900 mT or more. A magnetic field-responsive elastomer composition characterized in that the content of the soft magnetic filler (B) is 30% by volume or more and less than 60% by volume of the total composition.
2. The magnetic field-responsive elastomer composition according to claim 1, characterized in that the average particle size of the soft magnetic filler (B) is 15 μm or less.
3. The magnetic field-responsive elastomer composition according to claim 1, characterized in that the soft magnetic filler (B) is at least one soft magnetic material selected from the group consisting of carbonyl iron, Fe-Si alloy, Fe-Si-Cr alloy, magnetic stainless steel, and permendur.
4. The average particle size of the soft magnetic filler (B) is 15 μm or less. The magnetic field-responsive elastomer composition according to claim 1, characterized in that the soft magnetic filler (B) is carbonyl iron or Fe-Si alloy.
5. The organopolysiloxane resin (A) is (a1) Organopolysiloxane having alkenyl groups at least at both ends, The magnetic field-responsive elastomer composition according to claim 1, characterized by comprising (a2) a hydrogen organopolysiloxane having at least one hydrogen atom bonded to a silicon atom in one molecule, and (a3) a hydrosilylation catalyst.
6. The magnetic field-responsive elastomer composition is characterized in that the storage modulus G'1 (at frequency 1 Hz, measured temperature 25°C) of the cured product of the composition when a magnetic field with a magnetic flux density of 500 mT is applied increases by more than 50 times (G'1/G'0 > 50) compared to the storage modulus G'0 (at frequency 1 Hz, measured temperature 25°C) of the cured product of the composition when no magnetic field is applied.
7. The magnetic field-responsive elastomer composition is characterized in that, when a magnetic force of 500 mT is applied to a cured product of the composition, the storage modulus G'1s (frequency 1 Hz, measurement temperature 25°C) after 1 second increases by more than 10 times compared to the storage modulus G'0 (frequency 1 Hz, measurement temperature 25°C) when no magnetic force is applied (G'1s/G'0 > 10).
8. A magnetic field-responsive elastomer comprising a cured product of a magnetic field-responsive elastomer composition according to any one of claims 1 to 5.

Description

This invention relates to a magnetic field-responsive elastomer composition and its cured product, and more specifically, to a magnetic field-responsive elastomer composition that, when a magnetic field is applied, can form a cured product (elastomer) in which the storage modulus changes significantly in response to the applied magnetic field, and also exhibits excellent speed of change in the storage modulus. Magnetic field-responsive materials are known in which magnetic fillers are dispersed in a matrix resin, and their elastic modulus changes in response to the applied magnetic field. Such magnetic field-responsive materials have been proposed for use in vibration dampers and actuators, and as magnetic field-responsive dampers and actuators (see, for example, Patent Documents 1-3). For example, Patent Document 1 by the present applicant describes a magnetic field-responsive resin composition comprising a viscoelastic resin material in which a magnetic filler is dispersed, wherein the complex modulus of the resin composition at 10 Hz without an applied magnetic field is 4 × 10⁶ N/ m² or less, the hardness of the viscoelastic resin material is 0 to 30 on the Asker C hardness scale or 20 to 200 on the penetration scale, and the magnetic filler content relative to the total amount of the composition is 10 to 60 volume%, thereby obtaining a magnetic field-responsive resin composition that is soft without an applied magnetic field, exhibits a significant improvement in modulus when a magnetic field is applied, and has low frequency dependence of damping capacitance and complex modulus. Japanese Patent Publication No. 2013-64441Japanese Patent Publication No. 2003-119291Japanese Unexamined Patent Publication No. 2-263337 The magnetic field-responsive elastomer composition and its cured products of the present invention will be described in detail below. The magnetic field-responsive elastomer composition according to the present invention contains an organopolysiloxane resin (A) and a soft magnetic filler (B). The components contained in the magnetic field-responsive elastomer composition according to the present invention will be described below. [Organopolysiloxane resin (A)] First, the organopolysiloxane resin (A) will be described. The organopolysiloxane resin (A), a component of the magnetic field-responsive elastomer composition of the present invention, is a resin that forms a silicone polymer with siloxane bonds as its polymer backbone, and is a polymer material that can form a cured product (elastomer) while dispersing the soft magnetic filler (B), described later, in its polymer. Any type of silicone polymer can be used, including those with a curing temperature of room temperature type or heat curing type, curing methods of addition reaction type, condensation reaction type or UV curing type, and properties before curing of liquid or solid form. In addition to the organopolysiloxane, which is the main polymer, the organopolysiloxane resin (A) according to the present invention also contains additives such as a crosslinking agent for crosslinking the organopolysiloxane and a catalyst to promote the crosslinking reaction. In the present invention, a liquid type silicone polymer of the addition reaction type is preferably used from the viewpoint of excellent handling. In the present invention, it is important that the shear complex modulus (A) of the cured organopolysiloxane resin itself (according to JIS K7244-10, 25°C, frequency 1 Hz) is in the range of 2,500 to 50,000 Pa. By setting the shear complex modulus G* of resin (A), which is the matrix resin component of the magnetic field-responsive elastomer, to the range of 2,500 to 50,000 Pa, the shape of the cured magnetic field-responsive elastomer is maintained, the change in the elastic modulus of the magnetic field-responsive elastomer before and after the application of a magnetic field is greatly increased, and the change in the elastic modulus of the magnetic field-responsive elastomer after the application of a magnetic field is accelerated. Furthermore, regarding the shear complex modulus G* of the cured resin (A), from the viewpoint of obtaining a magnetic field-responsive elastomer with a larger change in modulus due to magnetic field application and a faster change in modulus after magnetic field application, it is more preferable to set the shear complex modulus G* (1 Hz) of the cured organopolysiloxane resin (A) to 2700 to 15000 Pa, even more preferable to set it to 2700 to 10000 Pa, and particularly preferable to set it to 2700 to 5000 Pa. More specifically, the organopolysiloxane resin (A) used in this invention preferably comprises an addition-reaction type organopolysiloxane resin containing an organopolysiloxane (a1) having alkenyl groups at least at both ends, a hydrogen organopolysiloxane (a2) having at least one hydrogen atom bonded to a silicon atom in one molecule, and a hydrosilylation catalyst (a3) as essential components. Of