Membrane material for loudspeaker chassis and material for dust caps of loudspeaker chassis

A β-polypropylene-based material reinforced with magnesium mica particles improves sound quality and structural strength in loudspeaker drivers and dust caps, addressing the unnatural sound and strength limitations of conventional materials.

DE202025004066U1Active Publication Date: 2026-04-16BRUSTMANN MARKUS
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Patent Information

Authority / Receiving Office
DE · DE
Patent Type
Utility models
Current Assignee / Owner
BRUSTMANN MARKUS
Filing Date
2025-12-29
Publication Date
2026-04-16

AI Technical Summary

Technical Problem

Common diaphragm and dust cap materials for loudspeakers produce sound that is far removed from natural sound.

Method used

Use of a membrane material comprising almost pure β-polypropylene with specific molecular and crystalline structure, reinforced with magnesium mica particles, for loudspeaker drivers and dust caps, to enhance sound quality and structural strength.

Benefits of technology

The material produces a more natural sound and enhances structural integrity, addressing the sound quality and strength issues of conventional materials.

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Abstract

Membrane material for loudspeaker drivers and material for dust caps of loudspeaker drivers, characterized in that it consists of pure or at least very pure β-polypropylene. The material preferably consists of isotactic polypropylene homopolymer. The crystallinity of the material is preferably between 40% and 65%. The crystals (β-polypropylene crystals) preferably have a size of 10 µm to 20 µm. For a crystal size of 15 µm, the side length is approximately 7.5 µm and the two large faces each have a size of approximately 146 µm. 2 The crystal's height is approximately 2.6 µm and its volume is approximately 380 µm³. 3 . The spherulites (clusters of crystals) of the material preferably have a size of 300 µm to 1200 µm.
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Description

[0001] Common diaphragm materials for loudspeaker drivers, such as paper or fiberglass in resin, produce a sound that is relatively far removed from natural sound. Common materials for dust caps also produce a sound that is relatively far removed from natural sound.

[0002] The membrane material for loudspeaker drivers and the material for dust caps of loudspeaker drivers described in claim 1 produce a more natural sound. The material is suitable, for example, for mid-bass drivers or tweeters.

[0003] The air inclusions in the material mentioned in claim 2 also lead to a strengthening of the material. Example implementation:

[0004] Membrane material and material for the convex dust cap of a broadband loudspeaker chassis with a total diameter of 94 mm and an effective piston area of ​​32 cm² 2and a circular groove and a conical membrane: The material is almost pure β-polypropylene, consisting of isotactic polypropylene homopolymer with a molecular mass of approximately 400,000. The distribution of molecular sizes (chain lengths) is relatively broad. The crystallinity of the material is approximately 55%. The size of the crystals (β-polypropylene crystals) is approximately 15 µm, and the two large faces of the crystals are approximately 146 µm. 2 large, the height of the crystals is then approximately 2.6 µm and the crystals then have a volume of approximately 380 µm³. 3 The size of the spherulites (clusters of crystals) of the material is approximately 350 µm. The material is produced by using a suitable nucleating agent, which is also a component of the cone membrane and the dust cap in very small quantities. The material of the exemplary embodiment is reinforced with magnesium mica (phlogopite) particles approximately 30 µm in size. The mica content is approximately 20% (by weight). The material thickness of the cone membrane and the dust cap is 0.5 mm. The circular dust cap of the speaker chassis has a diameter of 23 mm. The dust cap is glued to the cone diaphragm.