Molded Article Wood Grain Appearance Injection Molding
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Solution Overview
Problem
Existing methods for producing molded articles with a wood grain-like appearance face challenges such as labor-intensive film sticking, reduced yield due to film breakage, difficulty in applying patterns to curved shapes, and reduced mechanical strength and impact resistance, especially in blow molding.
Innovation Solution
A molded article with a wood grain-like appearance is created using a combination of a first thermoplastic material like polyethylene (PE) and a second polymer material like polyamide (PA), which are at least partially immiscible, with specific solubility parameters and melting points, along with a mixture of masterbatches that satisfy certain weight ratios and hue pairings, allowing for improved wood grain pattern presentation and recyclability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a printed film is stuck on the molded article, then a wood grain-like appearance is achieved, but labor is required and the film may break or melt during injection molding
Solution Approach 1:
The patent combines the wood grain pattern formation and coloring functions into a single integrated molding process. By incorporating colored resin particles with specific properties (higher viscosity, different melt flow index) into the base resin, the wood grain pattern is formed directly during injection molding through flow stripes, eliminating the separate film sticking process and its associated labor and complexity.
Solution Approach 2:
The patent creates a visual copy of wood grain appearance through flow stripes formed by colored resin particles. Instead of using actual wood or printed films, the process replicates the aesthetic characteristics of wood grain through controlled resin flow patterns, achieving the desired appearance without the drawbacks of physical wood or film applications.
2Manufacturing precision
If a printed film is stuck on the molded article, then a wood grain-like appearance is achieved, but the film breaks or melts during injection filling reducing yield
Solution Approach 1:
The patent merges the pattern formation and coloring into the base resin itself. The colored resin particles are mixed with the base resin to form a homogeneous molding material, ensuring the wood grain pattern is formed throughout the entire molding process without separate film layers that could break or melt and cause yield loss.
Solution Approach 2:
The patent creates a homogeneous mixture of base resin and colored resin particles. This uniform distribution ensures consistent wood grain pattern formation throughout the molded article and eliminates the risk of film defects such as breaking or melting that would occur with non-homogeneous film applications.
3Manufacturing precision
If a printed film is stuck on the molded article, then a wood grain-like appearance is achieved, but it is difficult to apply to articles having curved and/or complicated shapes
Solution Approach 1:
The patent integrates the wood grain pattern formation directly into the injection molding process. Since the pattern is formed by resin flow during molding, it automatically adapts to any mold cavity shape, including curved and complicated geometries, without requiring separate film application steps that would be difficult on complex surfaces.
Solution Approach 2:
The patent uses the dynamic flow characteristics of molten resin during injection molding to form the wood grain pattern. The flow stripes are created by the movement and stretching of colored resin particles as the resin fills the mold, allowing the pattern to naturally conform to any mold geometry including curved and complicated shapes.
4Ease of manufacture
If wood powder is dry-blended with pigment master batch, then coloring is achieved, but wood powder becomes a hindrance to producing grain pattern
Solution Approach 1:
The patent changes the key parameters of the colored resin particles compared to the base resin. Specifically, the colored resin particles have higher melt viscosity and a melt flow index difference of more than 20 with the base resin. These parameter changes enable the colored particles to form distinct flow stripes during injection molding, creating the wood grain pattern while maintaining easy manufacturing through dry blending.
5Strength
If impact strength is improved by material selection, then mechanical strength is maintained, but welding property between base resin and colored part deteriorates
Solution Approach 1:
The patent optimizes the melting point difference between the base resin and colored resin particles to be within 50°C. This parameter control ensures that both materials can be processed together at appropriate temperatures, maintaining good welding properties during injection molding while allowing selection of materials with suitable impact strength characteristics.
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 provides a molded article with a sharp and effective wood grain-like appearance while maintaining mechanical strength and barrier benefits, and offers improved recyclability, addressing the limitations of existing methods by enhancing pattern presentation and reducing material waste.
Implementation Method 1
a second polymer material that is at least partially immiscible with said first thermoplastic material
Implementation Method 2
said second polymer material has a Solubility_parameter (δ) of from about 10 (cal1/2cm−3/2) to about 20 (cal1/2cm−3/2)
Implementation Method 3
a melting point of from about 194° C. to about 280° C.
Data Source
AI summary
Disclosed is a molded article, wherein the article has at least one layer having a wood grain-like appearance, wherein the layer comprises: a) a first thermoplastic material that is selected from the group consisting of: polyethylene (PE), polypropylene (PP), copolymers thereof, and any combinations thereof; and b) a second polymer material that is at least partially immiscible with said first thermoplastic material, in which said second polymer material is selected from the group consisting of: polyamide, polyethylene terephthalate (PET), copolymers thereof, and any combinations thereof; wherein said second polymer material has a Solubility Parameter (δ) of from about 10 (cal1/2cm−3/2) to about 20 (cal1/2cm−3/2), and a melting point of from about 194° C. to about 280° C. The present invention also relates to a mixture of masterbatches used for manufacturing the above molded articles, and a method of manufacturing the above molded articles. The present inventions provide wood grain-like appearance, while maintaining mechanical strength and barrier benefit.