Co-Injection Molded Preform with Colored Layer for Visible Gradation

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Solution Overview

Problem

Conventional synthetic resin bottles with gradation patterns struggle to emphasize the pattern due to the colorless transparency of base material layers, which makes the intermediate colored layer invisible.

Innovation Solution

A synthetic resin preform with a colored layer formed on the outer circumference of a base material layer, using a second colored resin with a different color and a coating layer made from the first colored resin, achieved through a specific co-injection molding process where the second resin flows faster and penetrates the cavity first, creating a gradation region with decreasing layer thickness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If an intermediate colored layer is disposed between transparent base material layers by co-injection molding, then a gradation pattern is obtained, but the gradation pattern cannot be emphasized due to colorless transparency of the base material layers

Engineering Contradiction:

Improvegradation pattern formationVSAvoidvisibility of gradation pattern

Core Design Contradiction:

Ease of manufactureVSDifficulty of detecting and measuring

Solution Approach 1:

The patent applies color changes by making the base material layers themselves colored (first colored resin and second colored resin with different colors) rather than transparent. This allows the intermediate colored layer to be visible and the gradation pattern to be emphasized through the interaction of different colored layers with varying thicknesses.

Inventive Principle:

Principle #32Color changes

Solution Approach 2:

The patent uses composite materials by combining multiple colored resin layers with different properties. The first colored resin, second colored resin, and intermediate colored layer form a composite structure where each layer contributes to the overall gradation pattern visibility and aesthetic effect.

Inventive Principle:

Principle #40Composite materials

2Ease of manufacture

If a coloring agent is added to the base material to address transparency, then color is provided, but the intermediate layer is hidden and the gradation pattern becomes invisible

Engineering Contradiction:

Improvecoloring of base materialVSAvoidvisibility of intermediate layer

Core Design Contradiction:

Ease of manufactureVSDifficulty of detecting and measuring

Solution Approach 1:

The patent applies local quality by using different colored resins for different layers. The first colored resin and second colored resin have different colors, creating local color variations that make the intermediate colored layer visible while maintaining coloration throughout the base material layers.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

Instead of making the base material transparent with colorless resin and relying on the intermediate layer for color (which hides the pattern), the patent inverts the approach by making the base material layers themselves colored. This inversion ensures the intermediate layer remains visible and the gradation pattern is emphasized.

Inventive Principle:

Principle #13The other way round (Inversion)

3Difficulty of detecting and measuring

If a colored layer with varying thickness is formed to create gradation, then color density varies, but the transition may be too abrupt or invisible without proper base material coloring

Engineering Contradiction:

Improvevisibility of color density variationVSAvoidlayer thickness control

Core Design Contradiction:

Difficulty of detecting and measuringVSManufacturing precision

Solution Approach 1:

The patent uses color changes in the base material layers (first colored resin and second colored resin with different colors) to enhance the visibility of the gradation pattern. The varying thickness of the intermediate colored layer creates color density variations that are amplified by the colored base materials, making the gradation visible even with manufacturing variations.

Inventive Principle:

Principle #32Color changes

Solution Approach 2:

The composite structure of three colored layers works together to create visible gradation. The interaction between the first colored resin, intermediate colored layer, and second colored resin produces optical effects that emphasize the gradation pattern, compensating for difficulties in precise thickness control.

Inventive Principle:

Principle #40Composite materials

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 effectively emphasizes the gradation pattern by forming a colored layer with a different color on the outer side of the base material layer, while a thin coating layer from the first resin obscures the transition, resulting in a visually appealing and noticeable gradation pattern when biaxially stretch blow molded into a bottle.

Implementation Method 1

setting an injection rate of the second colored resin to be faster than an injection rate of the first colored resin, the first colored resin is caused to flow while stretching the second color resin after penetrating a center portion of the second colored resin located inside the cavity of the mold

Methodology Applied

Scientific EffectViscosity difference:

Data Source

PatentUS11472090B2Preform and bottle

Publication Date: 2022.10.18 YOSHINO KOGYOSHO CO LTD

AI summary

Provided is a method for manufacturing a preform (1). The method includes injecting into a cavity of a mold through the gate: (i) a first colored resin (R1) for a first predetermined time period, and (ii) a second colored resin (R2), having a color different from that of the first colored resin, for a second predetermined time period.