Prepreg Resin Viscosity Control for Low Tack and Resin Flow
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Solution Overview
Problem
Existing prepreg production methods face challenges in achieving low tackiness and resin flow while avoiding the use of solvents, leading to impaired processability and mechanical characteristics of fiber-reinforced composite materials.
Innovation Solution
A prepreg is produced by pre-curing a film-shaped resin material to increase its viscosity, stacking it on a fiber substrate, and impregnating one surface with a thermosetting resin composition, resulting in a resin layer with specific complex viscosities and low volatile content, which enhances handleability and reduces resin flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the thermosetting resin composition has high viscosity at room temperature, then the tackiness is low and adhesion is suppressed during handling, but the resin flow is also suppressed during curing
Solution Approach 1:
The patent applies preliminary action by pre-curing the film-shaped resin material before stacking it on the fiber substrate. This pre-curing step increases the viscosity of the resin composition in advance, which suppresses tackiness and resin flow during subsequent handling and molding operations, while still allowing the resin to be properly applied to the fiber substrate during the impregnation process
2Ease of manufacture
If the thermosetting resin composition has low viscosity, then the film-shaped resin material can be easily coated on the release sheet, but the tackiness increases and adhesion becomes excessive during handling
Solution Approach 1:
The patent uses preliminary action by performing pre-curing on the film-shaped resin material before it is stacked on the fiber substrate. This pre-curing increases the viscosity of the resin composition, which suppresses excessive tackiness and adhesion during handling operations, while the coating process is completed during the impregnation step where the resin is applied to the fiber substrate
3Manufacturing precision
If the thermosetting resin composition has high viscosity during curing, then resin flow is suppressed and burrs are reduced, but the resin cannot be easily coated on the release sheet during production
Solution Approach 1:
The patent applies preliminary action by pre-curing the film-shaped resin material before stacking it on the fiber substrate. This pre-curing step increases the viscosity of the resin composition in advance, which suppresses resin flow and reduces burrs during subsequent molding operations, while the coating process is completed during the impregnation step where the resin is applied to the fiber substrate under controlled conditions
4Ease of manufacture
If a solvent is used to reduce viscosity of the thermosetting resin composition, then the viscosity is easily reduced for better processability, but the volatile amount increases and mechanical characteristics deteriorate
Solution Approach 1:
The patent applies parameter changes by controlling the viscosity of the thermosetting resin composition through pre-curing treatment rather than using solvents. The pre-curing process modifies the chemical state and viscosity of the resin in a controlled manner, improving processability while avoiding the introduction of volatile components that would deteriorate mechanical characteristics
Solution Approach 2:
The patent converts the potential harm of high viscosity (which makes coating difficult) into a benefit by using pre-curing to increase viscosity in a controlled manner. The pre-cured resin film is then stacked on the fiber substrate and impregnated, allowing the high viscosity to suppress tackiness and resin flow during handling while maintaining proper coating application during the impregnation process
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 method facilitates better production process passability, improves dimensional accuracy of molded bodies, and maintains mechanical characteristics by minimizing tackiness and resin flow without using solvents.
Implementation Method 1
pre-curing a film-shaped resin material obtained by coating a release sheet with a thermosetting resin composition containing at least components [A] and [B] below, in which in the pre-curing step, a resin film is obtained in which the thermosetting resin composition has a viscosity of complex viscosity at 24° C.: η2*24 of 20,000 to 100,000 Pa·s and complex viscosity at 70° C.: η12*70 of 100 to 5,000 Pa·s
Implementation Method 2
the fiber substrate is impregnated with a part of the thermosetting resin composition of the resin layer
Implementation Method 3
A molded body for these products is obtained by pressurizing and heating the prepreg in an autoclave, a press machine, or the like and curing the prepreg
Data Source
AI summary
A prepreg is described having good handleability and a low resin flow, facilitating the work in the process of a molded body and improving the dimensional accuracy of the molded body, where the prepreg includes a fiber substrate; and a resin layer containing a thermosetting resin composition containing at least components [A] (thermosetting resin) and [B] (curing agent of [A]), stacked on one surface of the fiber substrate, wherein the fiber substrate is impregnated with a part of the thermosetting resin composition of the resin layer, the thermosetting resin composition having a complex viscosity η3*24 at 24° C. of 20,000 to 100,000 Pa·s and a complex viscosity η3*70 at 70° C. of 100 to 5,000 Pa·s, and a volatile amount of the thermosetting resin composition is 1 mass % or less when a total mass of the prepreg is 100 mass %.