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Consistent color is crucial for plastic products since it impacts brand identity and marketability. Plastic's appearance is based on opacity, texture, and gloss. Every modern manufacturer of opaque sheet plastic must always deliver the correct color to consumers. 

HunterLab's color measurement solutions help execute quality control throughout manufacturing processes. 

Factors that Affect the Appearance of Color

Environmental factors, optical illusions, and surface conditions determine the appearance of an object's color. Other factors include:

• Subjectivity: Eye sensitivity varies from person to person, causing color to appear different.
• Light sources: Different types of light, such as fluorescent, incandescent, and sunlight, have different effects on the appearance of color.
• Surfaces: Surface conditions such as texture and glossiness influence the object's color.
• Background: An object can appear a different color against a bright or dark background.
• Surface area: A color covering a large surface area appears brighter and more vivid than when covering a small object.

Spectrophotometers for the Color Measurement of Opaque Sheet Plastic

HunterLab offers instruments suited for color measurement of opaque plastics. Our Agera spectrophotometer caters to opaque plastics like films, sheets, enclosures, and pellets. It measures color across a spectrum with UV control. Additionally, it incorporates a 60-degree gloss measurement and a 5-megapixel camera to assist with sample positioning.

Plastic recycling is essential as the world continues to emphasize sustainability. Recycled plastic pellets from post-consumer and industrial waste offer value in various applications, including traffic cones, plastic chairs, detergent bottles, trash cans, and flower pots. 

Ensuring consistent color in products made from reprocessed materials can be complex. Here at HunterLab, we offer a range of solutions to measure the color of recycled pellets for precise results.

Challenges in Measuring Recycled Materials

Quantifying color in recycled plastic pellets presents unique challenges, such as:

• Material variations: Recycled pellets contain plastics from different sources, resulting in color variations. They are often blended to achieve a desired color. Color measurement can help ensure consistent blending ratios and a uniform final product color.
• Contamination: Foreign materials present in recycled pellets can affect color measurement accuracy. Implementing measures to minimize contamination in recycled pellets can improve color consistency.
• Physical form: Recycled pellets vary in size, shape, and opacity, affecting how light interacts with the material during measurement. These properties demand the right equipment and measurement methods for precision and consistency.

Best Practices for Precise Color Measurement

Spectrophotometers/colorimeters are the industry standard for precise color measurement. These devices analyze how light interacts with a sample and quantify the intensity of wavelengths across the visible spectrum to translate color into numbers. The following best practices will help you make the most of this technology to support your goals:

• Prepare and present samples accurately and consistently: It is crucial to maintain consistent sample preparation. Per ASTM D6290-19, operators must use a clean, optically clear and scratch-free sample cup filled to a sufficient depth to ensure effective opacity. Additionally, covering the sample cup with an opaque cover is crucial to block ambient room light and prevent external interference during measurement.
• Measure across a large area: The larger the sample area measured, the more precise and repeatable the results. Refer to ASTM D6290-19 Standard Test Method for Color Determination of Plastic Pellets for guidance on proper measurement methods. Specifically, the standard recommends taking three separate measurements using a "dump-and-fill" technique with fresh pellets to ensure an accurate and representative average.
• Determine the relevant color spaces: Choose a shared color space to establish communication throughout the production chain.
• Leverage color quality control software: Ensure your spectrophotometer integrates with or includes built-in color quality control software. This technology allows you to compare the color of your recycled pellets to target specifications or predefined color ranges.

Plastic recycling is essential as the world continues to emphasize sustainability. Recycled plastic pellets from post-consumer and industrial waste offer value in various applications, including traffic cones, plastic chairs, detergent bottles, trash cans, and flower pots. 

Ensuring consistent color in products made from reprocessed materials can be complex. Here at HunterLab, we offer a range of solutions to measure the color of recycled pellets for precise results.

Challenges in Measuring Recycled Materials

Quantifying color in recycled plastic pellets presents unique challenges, such as:

• Material variations: Recycled pellets contain plastics from different sources, resulting in color variations. They are often blended to achieve a desired color. Color measurement can help ensure consistent blending ratios and a uniform final product color.
• Contamination: Foreign materials present in recycled pellets can affect color measurement accuracy. Implementing measures to minimize contamination in recycled pellets can improve color consistency.
• Physical form: Recycled pellets vary in size, shape, and opacity, affecting how light interacts with the material during measurement. These properties demand the right equipment and measurement methods for precision and consistency.

Best Practices for Precise Color Measurement

Spectrophotometers/colorimeters are the industry standard for precise color measurement. These devices analyze how light interacts with a sample and quantify the intensity of wavelengths across the visible spectrum to translate color into numbers. The following best practices will help you make the most of this technology to support your goals:

• Prepare and present samples accurately and consistently: It is crucial to maintain consistent sample preparation. Per ASTM D6290-19, operators must use a clean, optically clear and scratch-free sample cup filled to a sufficient depth to ensure effective opacity. Additionally, covering the sample cup with an opaque cover is crucial to block ambient room light and prevent external interference during measurement.
• Measure across a large area: The larger the sample area measured, the more precise and repeatable the results. Refer to ASTM D6290-19 Standard Test Method for Color Determination of Plastic Pellets for guidance on proper measurement methods. Specifically, the standard recommends taking three separate measurements using a "dump-and-fill" technique with fresh pellets to ensure an accurate and representative average.
• Determine the relevant color spaces: Choose a shared color space to establish communication throughout the production chain.
• Leverage color quality control software: Ensure your spectrophotometer integrates with or includes built-in color quality control software. This technology allows you to compare the color of your recycled pellets to target specifications or predefined color ranges.

El índice de amarilleamiento de ASTM International proporciona un estándar medible para evaluar el amarilleamiento en materiales blancos o de color claro, como los plásticos. Este estándar determina el grado de amarilleamiento presente, lo que permite a las empresas realizar procesos de control de calidad para mantener la consistencia del producto. La prueba utiliza un espectrofotómetro para cuantificar la medición del color.

El sistema de colores APHA es la escala de medición más común para medir el amarilleamiento en líquidos. Se utiliza en industrias que van desde la producción química hasta el desarrollo farmacéutico.

Materiales que requieren observaciones de amarilleamiento

Varios plásticos requieren observaciones de amarilleamiento debido a los cambios que sufren estos materiales durante su procesamiento. Entre estos plásticos se incluyen:

• Cloruro de polivinilo (PVC)
• Policarbonato (PC)
• Ácido tereftálico purificado (PTA)
• Polietileno tereftalato (PET)

El amarilleamiento aparece en el PET debido a la oxidación. Con el creciente uso de PET reciclado (rPET), los fabricantes deben medir el color para contrarrestar el amarilleamiento y determinar la proporción correcta de abrillantadores ópticos necesarios para mitigarlo.

¿Qué es el índice de amarilleamiento?

El índice de amarilleamiento (YI) mide el amarilleamiento debido a los cambios en el producto. El índice de amarilleamiento ASTM E313 es el método más común para determinar el amarilleamiento en materiales como los plásticos. La norma proporciona índices definidos para medir el cambio con respecto al blanco ideal. Se calcula según la siguiente fórmula:

YI = (100CxX - CzzZ)/Y

Las variables X, Y y Z son valores triestímulos CIE, que expresan el color y cómo se percibe. Cx y Cz dependen de la fuente luminosa y del observador. Durante los cálculos, los usuarios eligen los valores de estos coeficientes en una tabla para que se correspondan con los ajustes del espectrofotómetro. La norma ASTM E313 combina los cálculos en un único valor, que define el grado de amarillez de una muestra. Cuanto menor sea el número, menos amarillo será el material.

El valor YI se suele indicar como la diferencia en el grado de amarillez entre una muestra del producto y el original o la referencia, y se designa como delta YI (∆YI).

ASTM Internationalの黄変指数は、プラスチックなどの白色または淡色材料の黄変度を評価するための測定基準を提供する。この基準は存在する黄変の程度を判定し、企業が品質管理プロセスを実施して製品の一貫性を維持することを可能にする。試験では分光光度計を用いて色測定を定量化する。

APHAカラーシステムは、液体中の黄色度を測定する最も一般的な測定尺度である。化学製品製造から医薬品開発に至るまで、幅広い産業分野で活用されている。

黄色を要する材料の観察

各種プラスチックは、加工過程で生じる変化のため、黄変の観察が必要である。これらのプラスチックには以下が含まれる：

• ポリ塩化ビニル（PVC）
• ポリカーボネート（PC）
• 精製テレフタル酸（PTA）
• ポリエチレンテレフタレート（PET）

PETの黄変は酸化によって生じる。再生PET（rPET）の使用が増加するにつれ、製造業者は黄変に対処するため色を測定し、それを軽減するために必要な蛍光増白剤の適正比率を決定しなければならない。

黄変指数とは何か？

黄度指数（YI）は製品変化による黄度を測定する指標である。ASTM E313黄度指数はプラスチックなどの材料における黄度測定で最も一般的な方法である。この規格は理想的な白色からの変化を測定するための定義済み指数を規定している。以下の式に従って算出される：

YI = (100CxX - CzzZ)/Y

X、Y、Z変数はCIE三刺激値であり、色とその知覚を表現する。 CxとCzは光源と観察者に依存します。計算時には、分光光度計の設定に対応する値をユーザーが表から選択します。ASTM E313規格ではこれらの計算を単一の数値に統合し、試料の黄度量を定義します。数値が低いほど、材料の黄色味が少ないことを示します。

YI値は通常、製品サンプルと原物または基準物との黄度差として報告され、デルタYI（ΔYI）と表記される。

The Yellowness Index from ASTM International provides a measurable standard for assessing the yellowness in white or light-colored materials, such as plastics. This standard determines the degree of yellowness present, allowing companies to perform quality control processes to maintain product consistency. The test uses a spectrophotometer to quantify the color measurement.

The APHA color system is the most common measurement scale for measuring yellowness in liquids. It serves industries ranging from chemical production to pharmaceutical development.

Materials That Require Yellowness Observations

Various plastics require yellowness observations due to the changes these materials undergo in processing. These plastics include:

• Polyvinyl chloride (PVC)
• Polycarbonate (PC)
• Purified terephthalic acid (PTA)
• Polyethylene terephthalate (PET)

Yellowness appears in PET due to oxidation. With the increasing use of recycled PET (rPET), manufacturers must measure color to counter yellowness and determine the correct ratio of optical brighteners required to mitigate it.

What Is the Yellowness Index?

The Yellowness Index (YI) measures yellowness due to product changes. The ASTM E313 Yellowness Index is the most common method for determining yellowness in materials like plastics. The standard gives defined indices for measuring the shift from ideal white. It is calculated according to the following formula:

YI = (100CxX - CzZ)/Y

The X, Y, and Z variables are CIE Tristimulus values, which express color and how it is perceived. Cx and Cz depend on the illuminant and observer. During calculations, users choose the values for these coefficients from a table to correspond with spectrophotometer settings. The ASTM E313 combines the calculations into a single value, defining the yellowness amount in a sample. The lower the number, the less yellow the material is.

The YI value is commonly reported as the difference in yellowness between a product sample and the original or reference, designated as delta YI (∆YI).

The Yellowness Index from ASTM International provides a measurable standard for assessing the yellowness in white or light-colored materials, such as plastics. This standard determines the degree of yellowness present, allowing companies to perform quality control processes to maintain product consistency. The test uses a spectrophotometer to quantify the color measurement.

The APHA color system is the most common measurement scale for measuring yellowness in liquids. It serves industries ranging from chemical production to pharmaceutical development.

Materials That Require Yellowness Observations

Various plastics require yellowness observations due to the changes these materials undergo in processing. These plastics include:

• Polyvinyl chloride (PVC)
• Polycarbonate (PC)
• Purified terephthalic acid (PTA)
• Polyethylene terephthalate (PET)

Yellowness appears in PET due to oxidation. With the increasing use of recycled PET (rPET), manufacturers must measure color to counter yellowness and determine the correct ratio of optical brighteners required to mitigate it.

What Is the Yellowness Index?

The Yellowness Index (YI) measures yellowness due to product changes. The ASTM E313 Yellowness Index is the most common method for determining yellowness in materials like plastics. The standard gives defined indices for measuring the shift from ideal white. It is calculated according to the following formula:

YI = (100CxX - CzZ)/Y

The X, Y, and Z variables are CIE Tristimulus values, which express color and how it is perceived. Cx and Cz depend on the illuminant and observer. During calculations, users choose the values for these coefficients from a table to correspond with spectrophotometer settings. The ASTM E313 combines the calculations into a single value, defining the yellowness amount in a sample. The lower the number, the less yellow the material is.

The YI value is commonly reported as the difference in yellowness between a product sample and the original or reference, designated as delta YI (∆YI).