Composite Housing Adhesion for Process Automation Devices
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Solution Overview
Problem
Automation field devices face challenges with insufficient adhesion between the housing and measuring components, leading to incorrect measurements and potential failure due to temperature fluctuations and the inability to meet IP68 protection standards in existing designs.
Innovation Solution
A composite housing material using a polymer matrix with an additive containing oxidized transition metals, such as titanates or zirconates, is applied to enhance adhesion and provide chemical bonding between the housing and container, allowing for a cold-casting system that reduces curing temperature and eliminates the need for oxide layer removal, thereby ensuring robust and protective encapsulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a potting material is used to encase the measuring tube, then the measuring components are stabilized and protected, but the adhesion between the housing body and the measuring tube is insufficient to meet IP68 protection requirements
Solution Approach 1:
The patent changes the chemical parameters of the potting material by incorporating specific additives (silane-modified polyepoxy resin, silane crosslinking agent, and coupling agent) that modify the material's surface properties and chemical reactivity. These parameter changes enable the potting material to form strong chemical bonds with the measuring tube surface, achieving both stabilization/protection and sufficient adhesion for IP68 protection.
Solution Approach 2:
The patent creates a composite potting material system combining multiple components: base polyepoxy resin, silane-modified polyepoxy resin, silane crosslinking agent, and coupling agent. This composite material leverages the synergistic effects of each component to achieve both the mechanical properties needed for protection and the chemical bonding required for adhesion to the measuring tube.
2Strength
If the outer surface of the container is oxidized to improve adhesion, then bonding is enhanced, but additional processing steps and cost are required
Solution Approach 1:
The patent enables the potting material to self-activate on the container surface through the coupling agent, which facilitates chemical bonding without requiring pre-oxidation or other surface treatment steps. The material essentially serves itself by automatically forming adhesive bonds when applied to the container surface, eliminating the need for separate oxidation processing.
Solution Approach 2:
The coupling agent acts as an intermediary substance that bridges the container surface and the potting material. Instead of requiring direct oxidation of the container surface, the coupling agent mediates the bonding process, enabling adhesion formation through chemical interaction between the coupling agent and both the container surface and the potting material resin.
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 solution achieves strong, permanent fixation and protection of measuring components against external influences, maintains measurement accuracy, and meets the IP68 protection class requirements, while being cost-effective and suitable for mass production.
Implementation Method 1
the additive comprises at least one chemical compound having an oxidized transition metal... the additive brings about a chemical bonding between the housing body and the outer surface of the container
Data Source
AI summary
The present disclosure relates to a process automation field device, comprising: a container for receiving and/or conducting a medium, the container having an outer surface; a measuring apparatus for determining a process variable of the medium; electronic components for operating the measuring apparatus; and a housing including a housing body, wherein: the measuring apparatus and the electronic components are disposed in the housing; the housing body is disposed on the outer surface; the housing body comprises a composite material; the measuring apparatus and the electronic components are at least partly surrounded by the composite material; and the composite material comprises a polymer matrix and an additive, which comprises at least one chemical compound including an oxidized transition metal from the fourth group of the periodic table. The present disclosure also relates to a method for producing the field device and to use of the additive to improve adhesion.