Nanofiber Sheet for Smooth Fiber Composite Surfaces

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Solution Overview

Problem

Fiber-reinforced composites often exhibit surface roughness due to fiber and binder resin phase differences, leading to visible 'print-through' and requiring additional costly and complex surface treatments to achieve smoothness.

Innovation Solution

A process involving a multilayer fiber preform with a nanofiber sheet applied to the fiber mat, where the nanofiber sheet is composed of monofilaments oriented parallel to the surface and embedded within a resin composition, reducing surface roughness without the need for separate surface layers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If traditional fiber composites are used, then weight reduction and complex shape capability are achieved, but surface smoothness deteriorates due to fiber and binder resin phase differences

Engineering Contradiction:
ImproveweightVSAvoidsurface smoothness
Core Design Contradiction:
Weight of moving objectVSManufacturing precision

Solution Approach 1:

The invention segments the fiber reinforcement into two distinct components: conventional fibers (1-50 μm diameter) that provide structural strength, and nanofibers (1-100 nm diameter) that specifically address surface smoothness. This segmentation allows each fiber type to perform its specialized function without compromising the other, resolving the contradiction between weight reduction and surface smoothness.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention creates a composite fiber structure combining conventional fibers and nanofibers within the same resin matrix. The nanofibers fill the gaps between conventional fibers and create a refined surface topology, while both fiber types contribute to weight reduction compared to metals. This composite approach simultaneously achieves weight savings and improved surface smoothness.

Inventive Principle:
Principle #40Composite materials

2Manufacturing precision

If additional surface layers (gel coat, primer, paint) are applied, then surface smoothness is improved, but manufacturing complexity and cost increase

Engineering Contradiction:
Improvesurface smoothnessVSAvoidmanufacturing process complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The nanofiber-reinforced composite performs the surface finishing function inherently through its own structure. The nanofibers create a naturally smooth surface topology that eliminates the need for separate gel coat, primer, or paint applications. The composite serves its own surface finishing needs, reducing manufacturing complexity and cost while achieving the desired surface smoothness.

Inventive Principle:
Principle #25Self-service

3Manufacturing precision

If thick gel coat or primer layers are applied, then surface smoothness and gloss are improved, but part thickness and weight increase

Engineering Contradiction:
Improvesurface smoothnessVSAvoidpart thickness
Core Design Contradiction:
Manufacturing precisionVSVolume of moving object

Solution Approach 1:

The invention applies surface optimization locally at the micro-nano scale through nanofiber incorporation, rather than adding thickness at the macro scale. The nanofibers (1-100 nm) create surface smoothness through their fine structure without requiring thick coating layers. This local quality improvement maintains part thickness and weight while achieving the desired surface smoothness and gloss.

Inventive Principle:
Principle #3Local quality

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

This approach significantly decreases surface roughness, enhancing visual appearance and gloss, while eliminating the need for additional surface coatings or treatments, thereby simplifying the manufacturing process and reducing costs.

Implementation Method 1

A portion of these particles become filtered out of the resin phase as it permeates into the fiber mass during composite manufacturing, forming a smooth surface layer

Methodology Applied
Scientific EffectFiltration: Filter (physical)

Implementation Method 2

as it permeates into the fiber mass during composite manufacturing

Methodology Applied
Scientific EffectPermeation: Permeation

Data Source

PatentEP3585607B1Fiber composite with reduced surface roughness and method for its manufacture
Publication Date: 2021.12.15 DOW GLOBAL TECHNOLOGIES LLC
  • EP3585607B1 patent drawingFigure 1~2
  • EP3585607B1 patent drawingFigure 3~4
  • EP3585607B1 patent drawingFigure 5~6

AI summary

Fiber reinforced composites are made by infusing a mass of reinforcing fibers with a resin composition (11). A thin sheet (6) of nano-sized monofilaments (7) is applied on at least one major surface of a fiber mass. The resin composition (11) is subsequently hardened to form the composite. This method produces a composite having a very smooth surface. Printout of the reinforcing fiber is greatly reduced without the need to mask it through the application of thick coatings or additional layers of material.