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Time: 2024-02-05
Plastic Bottle Coloring and Process Basics
Color matching refers to the process of creating desirable, aesthetically pleasing colors that meet color chart specifications, the client's requirements, and are cost-effective. Additionally, these colors must maintain consistency and not fade during processing and use. The basic colors used for matching are red, yellow, and blue (the primary colors).
Table of contents
Coloring Agents: Pigments and Dyes
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Pigment Characteristics
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Pigment Classification
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Inorganic Pigments
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Organic Pigments
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Dyes
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Pearlescent Pigments
Coloring Agents: Pigments and Dyes
Pigment Characteristics:
Pigments are coloring agents that do not dissolve in common solvents. To achieve optimal coloring performance, pigments must be evenly dispersed in plastic by mechanical or heated mixing methods.
Pigment Classification:
Pigments can be classified into organic and inorganic pigments based on their chemical structure.
Inorganic Pigments:
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Advantages: Good thermal stability, excellent weather resistance, high light stability, low cost, and superior dispersion performance.
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Examples: Titanium dioxide (TiO2), carbon black, etc.
Titanium Dioxide (TiO2) Series: There are three types: titanium dioxide, zinc oxide, and zinc barium white. Titanium dioxide can be found in two crystal forms: rutile and anatase. Rutile titanium dioxide has high refractive index, high opacity, stability, and good weather resistance. If titanium dioxide is not properly processed during production, it can result in black spots in the coloring process due to poor dispersion, which requires the use of dispersing agents for effective processing. It is mainly used to improve opacity and whiteness.
Carbon Black: Commonly used black pigment, inexpensive, and also provides ultraviolet (UV) protection for plastics (anti-aging) and conductive properties. Various types of carbon black can be produced by different production processes, resulting in a broad range of particle sizes and differing properties. Carbon black is classified into pigment carbon black and rubber-reinforcing carbon black. Pigment carbon black is further divided into high-pigment carbon black, medium-pigment carbon black, and low-pigment carbon black. Since carbon black particles are prone to aggregation, dispersing agents are required to enhance its color strength and dispersion.
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Organic Pigments:
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Advantages: High coloring power, bright colors, comprehensive color range, lower relative density, and small addition quantities.
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Disadvantages: Poor heat resistance, weather resistance, and opacity. Dispersibility is also suboptimal, and the price is higher than inorganic pigments.
Dyes:
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Advantages: Dyes are organic compounds that can be used with most solvents and colored plastics. They have low density, high coloring strength, and good transparency.
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Disadvantages: Their small molecular structure tends to migrate during coloring, and they can be more expensive than inorganic pigments, with some approaching the cost of organic pigments.
Pearlescent Pigments:
Pearlescent pigments, also known as mica titanium pearlescent pigments, are mica flakes coated with titanium dioxide. Based on the hue, they are categorized into silver-white, rainbow, and colored pearlescent pigments.
Important Notes for Pigment Purchase: When buying pigments, it is essential to know their Color Index (C.I.). C.I. is an international compilation of dye and pigment varieties published by the British Dyers Association and the American Association of Textile Chemists and Colorists. Each pigment has two numbers according to its chemical structure and application. This ensures clarity and consistency when purchasing pigments with the same molecular structure but different names. It also helps with proper color management and addressing issues during usage.