Cigarette factories have extremely strict and specific technical requirements for cellulose acetate (especially cellulose diacetate, abbreviated as CA, used in the manufacture of cigarette filters). The following is a detailed breakdown of the core technical requirements for cellulose acetate filter tow, from physicochemical indicators to processing performance:

I. Core Physical and Mechanical Properties

Single Filament Denier (Denier per Filament, dpf):

This is one of the most important indicators, usually between 1.5 and 5.0 denier.

Low dpf (e.g., 1.8-2.0): The tow is finer, with a larger specific surface area, resulting in a denser filter with higher efficiency in trapping tar and other particulate matter, and higher hardness.

High dpf (e.g., 3.0-5.0): The tow is coarser, resulting in a more porous filter with relatively lower draw resistance and a stronger sense of airflow. Cigarette factories choose based on product design (e.g., low tar, full flavor).

Total Denier:

Refers to the total thickness of each tow bundle, ranging widely (from several thousand to tens of thousands of denier). It determines the length and weight that a single filter can intercept, directly affecting production costs and filter specifications.

Crimp Performance:

Crimp count: The number of crimps per unit length. Affects the bulkiness, elasticity, and opening efficiency of the tow.

Crimp degree: The depth of the crimp. Good crimping ensures that the tow forms a uniform and stable three-dimensional network structure after opening, which is crucial for the hardness and uniformity of draw resistance of the filter. Insufficient crimping will lead to a filter that is too soft and easily deformed; excessive crimping will make opening difficult.

Cross-Sectional Shape:

Usually "Y" shaped or "dog bone" shaped irregular cross-sections. This design greatly increases the specific surface area of the tow, improving adsorption efficiency, while providing more inter-fiber voids to control airflow and draw resistance.

II. Filtration Performance and Sensory Indicators

Pressure Drop (PD):

Commonly known as "draw resistance." It is a key indicator for measuring the force required for air to pass through the filter. Tobacco manufacturers require precise and repeatable pressure drop values to match cigarette design and ensure consistent smoking experience. The pressure drop must be stable and uniform; otherwise, it will lead to variations in the taste of each cigarette.

Filtration Efficiency:

The ability to retain total particulate matter (TPM, mainly tar and nicotine) and specific harmful components (such as phenol and specific nitrosamines). This is the core function of the filter tip and requires precise control through adjusting tow specifications and additives (such as activated carbon and plasticizers).

Hardness:

The ability of the filter tip to resist deformation in the circumferential direction. Sufficient hardness prevents the filter tip from being crushed during processing, packaging, and by the consumer's lips. Hardness is closely related to the crimp and opening uniformity of the tow and the application of plasticizers (triacetin).

Plasticizer Requirements and Binding Efficiency:

Cellulose diacetate requires a plasticizer (almost exclusively triacetin) to bond and fix the monofilaments, forming a rigid filter rod.

Plasticizer Requirement Rate: The amount of plasticizer required to achieve the target hardness of the filter rod. Tobacco manufacturers want this value to be stable and moderate to control costs.

Binding Efficiency: The proportion of plasticizer effectively absorbed and solidified by the tow. High binding efficiency means faster production speed and less residual odor.

III. Chemical and Safety Indicators

Acetyl Content:

Usually required to be between 54.5% and 55.5%. This range determines the solubility (in acetone) and plasticizability of CA. Too low a content makes the fiber easily hydrolyzed; too high a content reduces compatibility with triacetin.

Free Acid Content:

Must be extremely low. Excessively high free acetic acid will cause the filter tip to have a sour taste, affecting the taste of the cigarette, and may accelerate equipment corrosion.

Residual Acetone and Solvent Content:

Must be strictly controlled. Residual solvents will produce a strong odor, seriously affecting the purity of the cigarette smoking experience.

Heavy Metals and Harmful Substances:

There are extremely strict limits on heavy metals such as lead, arsenic, and mercury, which must comply with food contact material or relevant national/industry standards. Odor and Taste:

The tow itself must be odorless or have only a very faint, neutral odor. Any foreign odors (such as chemical solvent odor, moldy odor, or oily odor) will directly contaminate the smoke, leading to serious sensory quality problems.

Whiteness and Color:

High whiteness and uniform color are required. Yellowing or color differences can affect the appearance of the filter tip and may indicate material degradation or contamination.

IV. Processing Performance

Openability:

The tow must unwind evenly and smoothly on high-speed filter rod forming machines without tangling, breaking, or forming uneven "cloud-like" patterns. This is a prerequisite for ensuring production efficiency and uniform filter rod quality.

Operating Speed Adaptability:

Modern high-speed filter rod forming machines can reach speeds of over 600 meters per minute. The tow must be able to adapt to this high-speed production without breaking, accumulating static electricity, or experiencing unstable opening.

Uniformity and Consistency:

Intra-batch uniformity: The parameters (dpf, crimp, strength) of the tow within the same batch must have minimal variation.

Inter-batch consistency: The performance of the tow between different production batches must be highly consistent. This is one of the most critical requirements for raw materials in large-scale cigarette manufacturing. Any fluctuations will lead to frequent adjustments of the production line and unstable product quality.

V. Packaging and Storage Requirements

Packaging Form:

Usually packaged in large cardboard boxes or plastic film wrapping, with multiple layers inside, and clearly marked with batch number, specifications, and other information. The packaging must effectively protect against moisture, contamination, and physical damage.

Storage Conditions:

Requires storage in a cool, dry, and well-ventilated warehouse, avoiding high temperature and high humidity. Cellulose acetate is hygroscopic, and changes in moisture content will affect its processing and filtration performance.

The technical requirements of cigarette factories for cellulose acetate tow constitute a complex system with multiple dimensions, high precision, and strong stability. It is not merely "a type of filter material," but a special raw material that combines "precision chemical product" and "high-performance engineering material." Cigarette factories and tow suppliers establish extremely close technical cooperation, controlling every detail through strict quality agreements (QA/QC) to ensure that the filter tip of every cigarette provides the expected smoking experience and stable harm reduction effect.