Multilayer Blow-Molded Color Gradient Structure Without Delamination

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Existing blow-molded articles with color gradients face issues of delamination, high material usage, poor gloss, and high haze due to the incorporation of effect and opacifying pigments, and are costly to produce in large scales, lacking control over opacity and mechanical resistance.

Innovation Solution

A multilayer blow molded article with transparent A-layers and a B-layer containing effect or opacifying pigments, formed through injection stretch blow molding without adhesives, achieving a color gradient and high opacity by varying the thickness ratio of A-layers to B-layers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If effect pigments and/or opacifying pigments are incorporated into large scale blow molded articles, then the article achieves desired optical effect, but the cost increases and manufacturing becomes difficult

Engineering Contradiction:
Improveoptical effectVSAvoidmanufacturing difficulty
Core Design Contradiction:
Illumination intensityVSEase of manufacture

Solution Approach 1:

The article is divided into multiple layers with different functions: transparent layers for gloss and effect pigment layers for optical effects. This segmentation allows each layer to be optimized independently, making manufacturing more manageable while achieving the desired optical effects.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Effect pigments and opacifying pigments are concentrated in specific B-layers rather than distributed throughout the entire article. This local concentration achieves the desired optical effects in critical areas while reducing overall pigment usage and manufacturing complexity.

Inventive Principle:
Principle #3Local quality

2Illumination intensity

If effect pigments and/or opacifying pigments are incorporated into blow molded articles, then the article achieves desired optical effect, but the gloss decreases and haze increases

Engineering Contradiction:
Improveoptical effectVSAvoidgloss and haze control
Core Design Contradiction:
Illumination intensityVSManufacturing precision

Solution Approach 1:

The article structure separates glossy transparent layers from effect pigment layers. The transparent A-layers provide gloss and clarity while the B-layers containing effect pigments provide optical effects, allowing independent optimization of gloss and optical effect properties.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Transparent A-layers act as intermediary layers between the external environment and the effect pigment B-layers. These transparent layers protect the effect pigments from direct exposure at the surface while still allowing their optical effects to manifest, maintaining gloss while achieving optical effects.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Manufacturing precision

If multiple layers are used to create color gradient, then the article achieves color gradient and opacity control, but delamination occurs and mechanical resistance decreases

Engineering Contradiction:
Improvecolor gradient and opacity controlVSAvoiddelamination resistance
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The thickness ratio of A-layers to B-layers is controlled within specific ranges (0.4 to 2.5 near the neck) to optimize both optical properties and mechanical strength. This parameter control ensures adequate bonding between layers while maintaining color gradient and opacity, preventing delamination.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The multilayer structure combines transparent thermoplastic materials with effect pigment-containing materials in a composite configuration. The specific layer thickness ratios and material selections create strong interlayer bonding while maintaining the desired optical effects and color gradients.

Inventive Principle:
Principle #40Composite materials

4Manufacturing precision

If two-step co-molding or overmolding method is used, then the article achieves color gradient with transparent outer layer, but the mechanical resistance decreases and layers delaminate

Engineering Contradiction:
Improvecolor gradient appearanceVSAvoidmechanical resistance
Core Design Contradiction:
Manufacturing precisionVSStrength

Solution Approach 1:

The thickness ratio of transparent A-layers to effect pigment B-layers is controlled within specific ranges (0.4 to 2.5 near the neck) to optimize both optical properties and mechanical strength. This parameter control ensures adequate bonding between layers while maintaining color gradient and opacity, preventing delamination.

Inventive Principle:
Principle #35Parameter changes

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 results in articles with a unique, premium appearance, high opacity, and resistance to delamination, using less material while maintaining glossy surfaces and optical effects, suitable for consumer products like bottles and jars.

Implementation Method 1

A method for making a blow molded article, according to the following steps: a. providing a preform mold for making a preform; b. injecting Stream-b comprising a comprising the molten thermoplastic resin and an effect pigment and/or an opacifying pigment into the preform mold with a flow rateb

Methodology Applied
Scientific EffectInjection molding:

Implementation Method 2

The color gradient in combination with the effect pigments can give the article a lustrous, pearlescent, iridescent, shimmery, sparkly, and/or metallic effect. Effect pigments have angle dependent optical effects when dispersed within a medium such as a coating or plastic resin

Methodology Applied
Scientific EffectLight scattering: Scattering

Implementation Method 3

Glossy articles can generally have a smooth outer surface that can enhance the degree of light reflected from that surface (i.e. specular reflectance is relatively high for a smoother surface)

Methodology Applied
Scientific EffectLight reflection: Reflection

Implementation Method 4

the A-layers are transparent and comprise a colored dye or pigment; wherein the outer surface comprises an axial color gradient formed by constituents from the A-layer forming the outer surface

Methodology Applied
Scientific EffectLight absorption: Absorption (EM radiation)

Data Source

PatentEP4087727B1Blow molded multilayer article with color gradient
Publication Date: 2026.03.25 PROCTER & GAMBLE CO
  • EP4087727B1 patent drawingFigure 1~2
  • EP4087727B1 patent drawingFigure 3
  • EP4087727B1 patent drawingFigure 4A~4B

AI summary

A blow molded multilayer article with a hollow body defined by a wall with an inner surface and an outer surface. The outer surface has an axial color gradient. The wall has multiple layers and at least one layer optionally contains an effect pigment and/or an opacifying pigment.