Wood Composite Adhesive System for Railroad Ties
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Solution Overview
Problem
The use of wood in railroad ties and other structures poses challenges due to environmental concerns from chemical preservatives, limited wood supply, and the need for recycling and repurposing, with existing binder compositions like isocyanates facing issues such as adhesion problems, extended cure times, and high viscosities.
Innovation Solution
A wood-based composite article is formed using a mixture of shredded wood pieces and a binder system comprising thermosetting plastic materials, including isocyanate compounds and isocyanate-reactive components, combined with a fiber component, which are processed under pressure and heat to enhance bonding and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If chemical preservatives are used to protect railroad ties from rot and insect infestation, then durability is improved, but environmental harm increases
Solution Approach 1:
The patent recycles discarded railroad ties by shredding them into wood particles and rebonding with new adhesive systems, converting waste material into new durable products while eliminating the need for additional chemical preservatives
Solution Approach 2:
The patent creates composite wood products by combining shredded wood particles with polyol-based adhesive systems and optional fiber reinforcements, producing materials that achieve durability through physical bonding and material composition rather than chemical preservation
2Strength
If isocyanate binder compositions are used to bond wood pieces, then bond strength is improved, but adhesion problems and extended cure times occur
Solution Approach 1:
The patent modifies the chemical parameters of isocyanate-based adhesive systems by using polyol compounds with specific molecular weights and functionalities, adjusting reaction kinetics to achieve faster cure times while maintaining bond strength
Solution Approach 2:
The patent introduces polyol compounds as intermediary substances that facilitate the bonding reaction between wood surfaces, enabling faster curing by mediating the chemical interaction and reducing direct isocyanate exposure time
3Strength
If isocyanate binder compositions are used to bond wood pieces, then bond strength is improved, but viscosity is high
Solution Approach 1:
The patent changes the physical parameters of the adhesive system by selecting polyol compounds with specific viscosity characteristics and molecular structures, reducing overall mixture viscosity while preserving the high bond strength properties of isocyanate-based systems
Solution Approach 2:
The patent uses readily available polyol compounds that can be easily mixed and applied, replacing high-viscosity isocyanate formulations with more workable adhesive compositions that maintain bonding performance
4Object-generated harmful factors
If wood supply is limited due to forestry restrictions, then environmental protection is improved, but product availability decreases
Solution Approach 1:
The patent recovers and recycles discarded railroad ties and wood waste materials, converting them into new durable wood composite products, thereby creating supply from post-consumer waste rather than virgin timber
Solution Approach 2:
The patent transforms the physical state and composition of discarded wood materials by shredding into particles and rebonding with adhesives, converting end-of-life products into new usable materials that expand available supply
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 resulting composite articles exhibit improved durability, weather resistance, and reduced emissions, with increased bond strength and flexural modulus, addressing the limitations of traditional wood-based materials and recycling challenges.
Implementation Method 1
The thermosetting plastic material component may comprise at least one isocyanate compound and an isocyanate-reactive component containing at least one isocyanate-reactive compound
Implementation Method 2
The method further includes the step of applying pressure and/or heat to the mass for an amount of time sufficient to form the article
Data Source
AI summary
A wood composite article includes a plurality of wood pieces and an adhesive system disposed on or dispersed among the plurality of wood pieces for bonding the plurality of wood pieces. The adhesive system includes a binder component and a fiber component. The binder component comprises a thermosetting plastic component such as unsaturated polyesters, epoxy, polyurea, polyurethane or combinations thereof, including for example, an isocyanate compound and an isocyanate-reactive component. The composite article may be formed into various objects such as railroad ties, fencing and the like.