Biodegradable Cartridge Wad Composition With Impact and Moisture Stability
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Solution Overview
Problem
Existing biodegradable materials for hunting and sport shooting cartridges, particularly wads, fail to meet stringent environmental standards like EN17033 for soil biodegradability, and suffer from issues such as low impact resistance, moisture sensitivity, and production inefficiencies in conventional injection molding.
Innovation Solution
A thermoplastic composition comprising ≥51% biodegradable polyesters with high fluidity and optionally plasticized starch, ensuring biodegradability in soil, high impact resistance, and compatibility with conventional injection molding processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If biodegradable materials are used in hunting and sport shooting cartridges, then environmental biodegradability is improved, but impact resistance and structural integrity deteriorate
Solution Approach 1:
The patent uses a composite material system combining biodegradable polyester (≥51%), plasticized starch (≤49%), and optional additives. This composite approach allows the material to achieve both biodegradability and mechanical strength by leveraging the complementary properties of each component: polyester provides structural integrity, starch enhances biodegradability, and plasticizers improve flexibility and processability.
Solution Approach 2:
The patent optimizes the composition parameters by specifying precise percentage ranges (polyester ≥51%, starch ≤49%) and controlling the melt volume rate (MVR ≥1 cc/10 min at 190°C/2.16 kg). These parameter changes ensure the material achieves the necessary balance between biodegradability and mechanical performance for withstanding firearm pressures while maintaining environmental compatibility.
2Object-affected harmful factors
If biodegradable polyesters with high starch content are used, then biodegradability in soil is improved, but moisture resistance and dimensional stability deteriorate
Solution Approach 1:
The patent carefully controls the starch content parameter (≤49%) and polyester content (≥51%) to optimize the balance between biodegradability and moisture resistance. This parameter optimization prevents excessive moisture absorption that would compromise dimensional stability while ensuring sufficient biodegradability in soil environments.
3Ease of manufacture
If conventional biodegradable compositions are used in injection molding, then production cost is reduced, but manufacturing precision and productivity deteriorate due to equipment modifications
Solution Approach 1:
The patent adjusts the material parameters, specifically ensuring an MVR ≥1 cc/10 min at 190°C/2.16 kg, which optimizes the melt flow characteristics. This allows the composition to be processed using conventional injection molding equipment without modifications, maintaining high productivity and manufacturing precision while keeping production costs low.
4Strength
If biodegradable materials with low MVR are used, then material strength is improved, but fluidity and ease of injection molding deteriorate
Solution Approach 1:
The patent optimizes the MVR parameter to be ≥1 cc/10 min at 190°C/2.16 kg, which provides the ideal balance between material strength and injection molding fluidity. This parameter setting ensures the material flows adequately during injection while maintaining sufficient strength for withstanding firearm pressures.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The composition achieves ≥90% biodegradability in soil within one year, maintains structural integrity under high pressure, reduces moisture absorption, and allows efficient production using conventional equipment, enhancing safety and longevity of firearms.
Implementation Method 1
the composition being biodegradable in soil... achieves ≥90% biodegradability in soil within one year
Implementation Method 2
reduces moisture absorption... moisture sensitivity
Data Source
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AI summary
Injection-moldable and soil-biodegradable thermoplastic composition, suitable for use in ammunition, especially in wads and other components of cartridges for hunting and sport shooting, comprising one or more biodegradable polyesters, preferably PBAT (polybutylene adipate terephthalate) and/or PBTSeb (polybutylene terephthalate, with sebacic acid), with a high fluidity, and in a percentage ≥51%, being able to be supplemented with plasticized starch. This composition achieves biodegradation in soil of more than 90% in a time much less than two years, together with high impact resistance, lower moisture absorption (with the associated advantages of greater dimensional stability, lower production cost and better and safer ballistics), compatibility with existing injection and manufacturing processes and lower production cost thanks to its greater fluidity.