Clarified Polypropylene Toothbrush Handle with Thin Ribs
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Solution Overview
Problem
Oral care implements, such as toothbrushes, require adequate strength to withstand varying user forces while minimizing plastic usage, as some users apply significant torque and pressure, and there is a need to reduce plastic content in mass-manufactured products without compromising strength.
Innovation Solution
A toothbrush handle design featuring a support structure made of clarified polypropylene with a web and ribs thinner than 2 millimeters, covered by a thermoplastic elastomer body, providing light transmissivity greater than 40% and structural integrity, along with a frame defining a void and elongate ribs extending along the handle axis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If the handle is made with thinner materials to reduce plastic usage, then the amount of plastic is reduced, but the strength may be compromised
Solution Approach 1:
The handle combines clarified polypropylene (transparent, rigid) for the support structure with thermoplastic elastomer (flexible, cushioning) for the body portion. This composite construction allows thin walls (reducing plastic) while maintaining strength through material synergies - the rigid polypropylene provides structural integrity and the flexible TPE provides impact resistance and comfort.
Solution Approach 2:
The handle is divided into distinct functional zones: a rigid support structure (web and ribs) made of clarified polypropylene and a flexible body portion made of thermoplastic elastomer. This segmentation allows each material to be optimized for its specific function - structural support versus user comfort - enabling thin-wall construction without sacrificing overall handle strength.
2Strength
If the handle is made with thicker materials to increase strength, then the strength is improved, but the light transmissivity is reduced
Solution Approach 1:
Different portions of the handle have different thicknesses and material properties optimized for their specific functions. The support structure (web and ribs) uses thin walls (≤2mm) of rigid clarified polypropylene to maximize light transmissivity where structural support is needed, while the body portion uses thicker flexible TPE where cushioning and grip comfort are priorities. This local optimization allows the handle to be both strong and translucent.
3Strength
If the handle uses rigid materials to withstand user forces, then the strength is improved, but the tactile comfort is reduced
Solution Approach 1:
The handle combines rigid clarified polypropylene for structural support with flexible thermoplastic elastomer for user contact surfaces. The rigid polypropylene support structure withstands bending and torque forces, while the flexible TPE body portion provides tactile comfort and grip during use. This material combination resolves the contradiction between strength and comfort.
Solution Approach 2:
The handle is segmented into a rigid support structure and a flexible body portion. The rigid portion (clarified polypropylene web and ribs) handles mechanical loads, while the flexible portion (TPE body) contacts the user's hand, providing comfort and adaptability to different grip styles. This functional segmentation allows each material to excel at its designated task.
Data Source
AI summary
A toothbrush handle includes a support structure formed of clarified polypropylene and a body formed of thermoplastic elastomer disposed on the support structure. The support structure includes a web having a thickness in a first direction orthogonal to an axis of the toothbrush handle of less than 2 millimeters and at least one rib depending from the web and having a thickness in a second direction, orthogonal to the axis and angled relative to the first direction, of less than about 2 millimeters. The body at least partially covers the web and the at least one rib. The handle has a light transmissivity of greater than 40% through a portion of the handle at which the body covers the web and the at least one rib.