What are the Common Optical Brightener
Optical Brightener,Also known as fluorescent whitening agents, they are a type of organic compound that can absorb ultraviolet light that is invisible to the human eye (wavelength of about 300-400 nanometers) and excite longer wavelength blue purple or blue visible light (wavelength of about 420-480 nanometers).
One key point: Optical Brightener itself cannot ‘bleach’ objects. It cannot remove color through chemical reactions, but rather “brightens” and “whitens” through optical compensation principles. Many items, such as paper, textiles, and plastics, may appear slightly yellowish on their own because they reflect less blue light. The blue light it emits can compensate for this deficiency, neutralize the yellow tone, and make objects appear whiter and brighter.
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Classification of Optical Brightener?
1. Classified by chemical structure
This is the most diverse type of Optical Brightener, particularly adept at swimming in water. So, areas that require water solubility, such as laundry detergent, laundry detergent, papermaking, and soap, are almost their world. For example, VBL, which we often hear about, is a common type.
This type is known as the “hard bone”, characterized by heat resistance, sun resistance, and stability. They are not very hydrophilic, but they are particularly compatible with oily plastics and synthetic fibers. So the plastic washbasins, electrical casings, and Optical Brightener in your polyester clothes are mostly from this school, such as OB-1.
This type of Optical Brightener is more specific and particularly fond of acrylic fiber (the kind of synthetic yarn that looks a lot like wool). If you see a shiny white acrylic sweater, it’s likely due to it.
Coumarin type: This type is the “atmosphere group”, which emits particularly strong and beautiful fluorescence, but has a disadvantage of being a bit “sun sensitive” and slightly less durable, so it is more commonly used in places where light resistance is not high, such as some coatings, inks, or low-end textiles.
2. Classified by the application objects of Optical Brightener
The textile industry: This is a broad category, which can be further subdivided. There are those who specialize in serving cotton and linen, those who specialize in dealing with polyester, and those who serve acrylic, emphasizing a “professional match”.
In the papermaking industry, from news paper to high-quality copperplate paper, if you want paper to look fair and transparent, you cannot do without them. Optical Brightener is directly mixed into pulp or coated on the surface during the papermaking process.
The detergent industry: This is what we are most familiar with. The function of Optical Brightener is to quietly adhere to the fibers when you wash clothes, which is equivalent to applying a layer of “invisible whitening makeup” to each piece of clothing in advance.
In the plastics and coatings industry, these optical brighteners must be able to withstand high temperatures, not decompose during plastic melting and molding, and be evenly dispersed within the material.
Common Optical Brightener
Related Products
Chemical type: stilbene type
Features and applications: This is absolutely the most important person in the laundry and paper industry, who has made outstanding contributions. Its greatest ability is its strong hydrophilicity, which has a natural affinity for cellulose materials such as cotton and paper, and can firmly adhere to them. Moreover, it is affordable and has stable performance, so it has been a “standard” for mass washing products and cultural paper for decades. As long as you have washed white clothes with laundry detergent, you have almost certainly seen its effect.
Appearance: A light yellow powder that looks ordinary and unremarkable.
Attention: Although it performs well on cotton and linen, its effect on synthetic fibers such as polyester and acrylic is mediocre. So now many laundry detergents targeting multifunctional fabrics will mix it with other types of Optical Brightener.
Chemical type: stilbene type
Features and Applications: This is a new generation ace that has emerged with the popularity of concentrated liquid laundry detergent. It is in the same field as its predecessor VBL, but its skill points are more inclined towards modern liquid formulas. It has excellent water solubility and can exist stably in liquid environments for a long time without precipitation or crystallization, perfectly solving the storage problem of liquid laundry detergent. The blue light emitted by it is more greenish and bright, in line with modern aesthetics, which can give white clothes a “cold white skin” translucent feeling.
Appearance: It is usually a directly prepared light yellow liquid, which is convenient to use.
Attention: Its performance is optimized for liquid detergents. If you are making solid soap or powder, using it may not be very cost-effective.
Chemical type: Benzoxazole type
Features and Applications: This is the commonly used Optical Brightener in the plastic kingdom. Its core skills are super heat resistance, migration resistance, and light resistance. The temperature of plastic during processing can easily reach one or two hundred degrees Celsius, and OB-1 can handle it calmly. Moreover, it will not easily escape (migrate) from the plastic and can withstand sunlight, ensuring that plastic products can maintain a bright white color for a long time without yellowing. From food packaging bags to home appliance casings, and even plastic parts for cars, its applications are extremely extensive.
Appearance: Fine crystalline powder in yellow green color.
Attention: It is basically insoluble in water and is “oily”, so do not try to put it in water to wash clothes, as it will be completely ineffective. Mechanical force is required to evenly disperse the plastic material during use.
Chemical type: Benzoxazole type
Characteristics and Applications: This is an Optical Brightener in the field of synthetic fibers, especially polyester fibers. The dyeing of polyester requires high temperature and high pressure, and the ER series whitening agents are designed for this harsh environment. It can penetrate into polyester fibers at high temperatures like a dispersed dye, achieving a bright white effect from the inside out, making polyester fabrics such as sportswear and sun protection clothes appear very pure and bright white.
Appearance: Usually a ground light yellow dispersion or slurry.
Attention: Its application process requires relatively high requirements and usually needs to be carried out synchronously with the dyeing process. It is processed at a high temperature of around 130 ℃ and is not suitable for later addition at home.
Chemical type: Styrenetriazine type
Characteristics and Applications: This is a true “old master” in the paper industry, with a transcendent status. It has a high affinity for plant fibers and a very high whiteness value, with a pure color tone. The key is that it can perform well in both the process of adding pulp and surface coating in papermaking, making the paper present a very soft and comfortable natural white color, rather than the dead white color. It can often be seen in high-end photocopy paper, copperplate paper, and decorative base paper.
Appearance: Bright pale yellow powder.
Attention: Its performance is greatly affected by the pH value of the papermaking system, and precise control of process conditions is required to achieve optimal results.
Chemical type: Dibenzoxazolyl
Features and Applications: This can be seen as an upgraded version or close relative of plastic expert OB-1, also belonging to the benzoxazole family. Its heat resistance and migration resistance are even better than OB-1, and its fluorescence intensity is very high. It is not only used for general plastics, but also excels in some high-performance engineering plastics (such as PC, ABS alloy) and high-end polyester spinning processes, which can bring extremely bright white visual effects.
Appearance: Bright yellow green powder.
Attention: The price is relatively expensive and considered a “high-end product” among whitening agents, generally used in products with special whiteness requirements.
Chemical type: stilbene type (specially designed with molecules)
Characteristics and applications: This is a “special forces soldier” because it has a unique skill: tolerance to chlorine bleach. Ordinary Optical Brightener immediately dies when encountering chlorine containing bleach such as 84 disinfectant, and its molecular structure is destroyed, causing clothes to turn yellow or even red. But FWA-24 has a unique molecular structure that can withstand attacks from chloride ions. So, it is specifically used in some fields that require frequent chlorine bleaching disinfection, such as towels for high-end swimming pools and bedding fabrics for hospitals and hotels.
Appearance: Light yellow powder.
Attention: Its “chlorine resistance” is also limited, and it cannot withstand high concentrations or long periods of time. Moreover, its price is significantly higher than that of ordinary varieties.
Chemical type: Biphenyl diphenyl type
Characteristics and Applications: This is an emerging force in the detergent industry in recent years and a strong competitor to the liquid ace CBS-X. Its biggest advantage is that while maintaining extremely high water solubility and stability, it has better acid and hard water resistance. This means that even if the water quality at the user’s home is hard or acidic, its whitening effect will not be compromised. Many new concentrated laundry detergents claiming to be “suitable for all scenarios” are beginning to favor it.
Appearance: Light yellow liquid or transparent paste.
Attention: Its production process is relatively complex and the cost is currently relatively high, and it is gradually being promoted.
Chemical type: Pyrazoline type
Features and Applications: If the ER series is the guardian of polyester, then KSN is the “exclusive consultant” for acrylic (synthetic wool). It has extremely high directness to acrylic fibers and can be dyed under relatively mild conditions (such as in boiling water), emitting bright blue purple fluorescence and whitening acrylic products exceptionally beautifully. The fluffy, white acrylic yarn or carpet in your home is likely to have been treated with it.
Appearance: Light yellow or yellow brown powder.
Attention: It is mainly used for acrylic fiber and has poor performance when applied to other fibers, with strong professionalism.
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