Specification

Fluorescent Whitening Agent KSM is a liquid, distyrylbiphenyl-type (or stilbene-type) fluorescent whitening agent. It is commonly classified as C.I. Fluorescent Whitening Agent 263.

The product appears as an amber transparent liquid. It is an anionic whitening agent with a reddish (red) fluorescence hue. The product is stable to hard water, acids and alkalis, sodium hydrosulfite, and peroxides, but is unstable to chlorite and hypochlorite.

Max. UV absorption wavelength:350nm	C.I. No.: 263
Appearance: amber transparent liquid	Solid content: 20%

Features

Redish tone; low substantivity; Stable to hard water,acid, alkaline, sodium hydrosulfite and peroxide, but not stable to chlorite and hypochlorite.

Applications

Mainly applied in paper-making, surface sizing, coating processes;Also applied in whitening of cotton, linen, cellulose fiber fabric; Brightening of light tone fabrics; Pad dyeing of cotton;
Compatible with starch and resin finishing agent when applied in cotton pad dyeing.
Whitening of blended fabric of coton and other synthetic fiber.

Performance Characteristics

1. Red Fluorescence Hue
The fluorescence hue is reddish, achieving a unique whitening effect on specific paper grades or fabrics.

2. Low Directness (Substantivity)
Low affinity for fibers, making it suitable for surface addition and reducing loss when added to pulp.

3. Good Chemical Stability
Stable to hard water, acids and alkalis, sodium hydrosulfite, and peroxides, offering a wide range of applicability.

4. Limitation
Unstable to chlorites and hypochlorites; avoid use in chlorine-containing bleaching environments.

5. Good Compatibility
Compatible with starch, CMC, PVA, anionic and weakly cationic synthetic sizing agents.

Scope of Application

Fluorescent Whitening Agent KSM is widely applicable to the following fields:

Application Field	Specific Uses
Paper Industry	Surface sizing, coating processes (poor performance in pulp addition due to low directness)
Textile Industry	Whitening of cotton, linen, and cellulosic fiber fabrics; brightening of light-colored fiber fabrics; pad dyeing of cotton; whitening of blended fabrics of cotton and synthetic fibers
Discharge Printing	Compatible with starch and resin finishing agents for use in discharge printing

Usage and Dosage

Paper Industry

Surface Sizing
Used together with CMC, PVA, starch, and anionic or weakly cationic synthetic sizing agents. Dosage: 0.1% – 2.0% (based on absolutely dry pulp or sizing solution).

Coating Process
Conventional reference dosage: 0.1% – 1.4% (based on coating weight).

⚠️ Note: Due to the low directness of KSM, it is not recommended for pulp addition (wet end) , as low retention and severe loss will result in poor economy.

Textile Industry

Cotton Pad Dyeing
Can be used compatibly with starch and resin finishing agents.

Blended Fabrics
Suitable for whitening blended fabrics of cotton and other synthetic fibers.

Comparison with Other Common Paper Whitening Agents

Model	Sulfonation Degree	Fluorescence Hue	Directness	Recommended Addition Point	Key Features
VBL	Disulfonic	Blue-violet	High	Mainly pulp (wet end)	Economical dosage, high retention rate
APC	Tetrasulfonic	Blue-violet	Medium	Universal (pulp/sizing/coating)	Strong versatility, widest application
KSM	Stilbene-type	Red	Low	Surface sizing / Coating	Red fluorescence hue, distinctive character
APH	Hexasulfonic	Blue-violet	Low	Surface sizing / Coating	Strongest whitening ability

💡 Selection Tip: The core feature of KSM is its red fluorescence hue. If you need a reddish whitening effect (rather than the conventional blue-violet hue), KSM is an ideal choice. However, due to its low directness, it is only suitable for surface sizing and coating processes (not for pulp addition).