White Paper on Pre-Dispersion Technology for Cellulose Acetate Butyrate Pigments: Core Principles and Practice

Pigments usually exist in the form of dry powder when they leave the factory, and agglomerates are formed between pigment particles by van der Waals force and electrostatic force, with particle sizes ranging from a few microns to hundreds of microns. These powder pigments are immediately added to the coating products or ink system, and the ideal coloring effect cannot be obtained-the pigment agglomerates will create color spots, insufficient hiding power and gloss reduction in the coating products. The traditional solution is to mechanically grind the pigment through a sand mill to open and spread the agglomerates to the original particle size range of the pigment. This process is energy-consuming and time-consuming, and the grinding process might harm the pigment crystal structure, affecting the color strength and weather resistance.

The core concept of pigment pre-dispersion methodology is to advance the dispersion process to the pigment production or processing link, and complete a high level of dispersion before the pigment enters the final consumption system. According to the product form, pigment pre-dispersion methodology can be divided into three categories: color paste (fluid), masterbatch (solid granular) and color chip (solid flake or granular). Among them, CAB color film with cellulose acetate butyrate as the carrier, through the melt dispersion process to pre-spread the pigment into a elevated levels of granular form, both the storage stability of solid items and the advantages of high dispersion of fluid items, is the pigment pre-dispersion methodology in the most balanced thorough performance of one of the categories.

Cellulose acetate butyrate (CAB) is a kind of thermoplastic resin material obtained by esterification modification of natural cellulose. Compared with unmodified cellulose, CAB has good aquatic environments resistance, chemical resistance and weather resistance, while retaining the environmental renewable characteristics of cellulose materials. The molecular structure of CAB contains two substituents, acetyl and butyryl, and the ratio of the two determines the physical and chemical characteristics of CAB. The higher the acetyl content, the better the chemical resistance and heat resistance of the material; the higher the butyryl content, the better the solubility and flexibility of the material in organic solvents. The CAB model frequently applied in color chip applications usually has an acetyl content of 2-15% and a butyryl content of 35-39%, which achieves a good stability between solvent-based products solubility and film toughness.

The advantages of CAB as a color chip carrier are mainly reflected in four aspects. First, CAB has good film-forming characteristics and forms a transparent and glossy continuous film after drying, which helps to enhance the appearance condition of the coating products. Second, the molecular chain of CAB contains a substantial number of hydroxyl groups and ester groups, which can form physical adsorptive processes and hydrogen bonding with the surface of the pigment particles, efficiently preventing the re-agglomeration of the pigment particles. Third, CAB is dissolves in a variety of common organic solvents, such as acetone, ethyl acetate and butanone, and is compatible with most manufacturing coatings and ink systems. Fourth, CAB itself is non-toxic and tasteless, and meets the regulatory standards to vulnerable consumption scenarios such as food contact materials and children's toy coatings. Elion has invested a lot of research and research resources in the screening and modification of CAB carriers, and has developed a variety of special models of modified CAB carriers to meet the needs of different consumption scenarios.

The manufacturing process of CAB color chips mainly includes four core processes: batching, melt dispersion, granulation and post-processing. The compounding process requires precise manage of the ratio of pigments, CAB carriers and functional additives (such as dispersants, wetting agents and anti-flocculants). The choice of pigment needs to be determined according to the target color and consumption performance standards; the type and amount of CAB carrier need to be determined according to the surface characteristics of the pigment and the compatibility of the target system; the type and amount of additives need to be determined through experimental optimization. Elion adopts an automated and precise batching system in the batching process to ensure the consistency of the formula of each batch of items.

Melt dispersion is the core process that determines the condition of CAB chips. The precisely proportioned mixture of pigment and CAB is fed into a high shear mixing extruder and melt mixed under controlled temperature (typically 180-220°C) and high shear conditions. The CAB carrier softens and encapsulates the pigment particles at high temperature, and the pigment agglomerates are opened and uniformly dispersed in the CAB melt under the action of shear force. Key manage parameters to this process include temperature, shear rate, mixing time, and pigment addition sequence. If the temperature is too low, the CAB carrier viscosity is too substantial, and the dispersion effect is poor; if the temperature is too high, the CAB might undergo thermal degradation, which will affect the product performance. Ilion's melt dispersion process uses a twin-screw extruder and a precision temperature manage system to ensure consistency and stability of the dispersion effect.

Granulation measure The melt-dispersed mixture is cut into a uniform granular or flake product by a granulator. The mesh size of the granulator determines the particle size specification of the final product. The frequently applied CAB color chips have a particle size range of 0.5-2.0mm. The smaller the particle size, the larger the specific surface area, and the faster the dissolution during consumption, however it also increases the difficulty and cost of production. According to the needs of different product series, Elion selects the optimal particle size range. Post-processing includes cooling, drying, screening and packaging to ensure that the product is delivered to the customer in a dry, low-dust condition.

The condition evaluation of CAB chips needs to cover three aspects: pigment performance, carrier performance and final consumption performance. The pigment performance evaluation index includes tinting strength, color coordinates (CIE L * a * B * value), fineness, dispersibility, weather resistance, and the like. The tinting strength is quantified by comparison with a standard reference, the higher the tinting strength, the greater efficient the pigment is applied. Color coordinates reflect the precise location of the color and are the basic data to color matching. The fineness reflects the final particle size level of the pigment dispersion, which is usually required to have no obvious graininess below 25 microns.

The performance evaluation indexes of the carrier include solubility, viscosity, transparency, toughness and chemical resistance. The dissolution rate of CAB carrier in the target solvent-based products determines the ease of consumption of the color film; viscosity affects the rheological characteristics and construction feel of the color paste; transparency determines the consumption effect of the color film in the transparent coating products; toughness and chemical resistance affect the physical and chemical characteristics of the coating products after film formation. Elion conducts a thorough carrier performance test to each batch of CAB color film items to ensure that all indicators meet factory standards.

The final consumption performance evaluation is the thorough evaluation closest to the actual consumption scenario. It is necessary to prepare CAB color film into color paste or immediately add it into the coating products system, prepare coating products samples by film making, spraying or dipping, and then measure the thorough performance of the coating products, such as appearance, color, gloss, adhesion, hardness and weather resistance. This evaluation process is usually carried out during the customer consumption verification phase, and Elion's technical service team can provide customers with technical support and data reports to consumption performance evaluation.

When selecting CAB color chips, it is first necessary to clarify the target consumption system. Different coating products systems (such as polyurethane, acrylic, epoxy, nitro, etc.) have different compatibility standards to CAB carriers, and it is necessary to select a CAB model that matches the target resin system. Secondly, it is necessary to choose the pigment type according to the color effect standards-organic pigments have bright colors and high tinting strength, however their weather resistance is usually not as good as inorganic pigments; inorganic pigments have good weather resistance and hiding power, however the color saturation is comparatively low; special effect pigments (Such as metal powder, pearlescent powder) can give the coating products a unique visual effect. Elion's technical team can provide professional product selection suggestions according to the specific needs of customers.

When using CAB color chips, it is recommended to add the color chips to the solvent-based products to fully swell and dissolve, and then add the resin and other components. The dissolution process needs to manage the stirring speed-first consumption a high-speed disperser to break up and soften the color chips (about 30 seconds to 1 minute), and then decrease the rotation speed to continue stirring until completely dissolved (about 2-5 minutes). overuse high-speed shearing time might lead to the breakage of CAB carrier molecular chain and affect the film-forming performance. to applications that require high color consistency, it is recommended to filter the color paste before each consumption to remove undissolved particles or impurities that might be present and to ensure the final fineness and appearance of the coating products.

CAB color film methodology is continuously evolving in three directions. The first is elevated levels, by optimizing the carrier formula and dispersion process to further enhance the pigment content in the color film, decrease the customer's carrier dosage and thorough formula cost. The second is functionalization, which integrates functional additives such as anti-ultraviolet agents, antioxidants, and flame retardants into the CAB carrier, so that the color chip has greater additional functions. The third is intelligent, introducing digital color matching tools and condition traceability system to realize the whole process data regulation from formula design to production delivery. As a pioneer in the domestic color methodology sector, Elion will continue to invest in research and research resources to promote the iterative upgrade of CAB color film methodology and provide customers with greater competitive items and solutions.

Cellulose acetate butyrate (CAB) pigment pre-dispersion methodology uses CAB as the carrier, through precise melt dispersion and granulation process, the pigment is pre-dispersed into high-levels granular form, which has multiple advantages such as high dispersion efficiency, batch stability, convenient consumption and long storage life. This white paper systematically combs the technical principle, manufacturing process, condition evaluation system and selection suggestions of CAB color film, and provides a thorough reference framework to technical practitioners in the sector. With the continuous improvement of ecological preservation, efficiency and condition standards in the paint and ink sector, the market consumption space of CAB color film will be further expanded. Elion will continue to cultivate the field of CAB color film methodology and drive the sector's progress with technological innovation.

Q: What is the essential difference between CAB and ordinary pigment mixtures?

A: The essential difference lies in the dispersion state. The agglomerate structure of the pigment in the ordinary pigment mixture remains basically unchanged during the mixing process, while the CAB color sheet is dispersed by melt high shear during the manufacturing process, and the agglomerate of the pigment has been fully opened and physically wrapped by the CAB molecular chain. Form a uniform micro-dispersion structure. This structural difference allows CAB chips to be fully utilized without the need to additional grinding and dispersion processes in the final consumption.

Q: How environmentally friendly is the CAB carrier? Does it contain harmful substances?

A:CAB is obtained by esterification modification of natural cellulose, does not contain plasticizers such as phthalates and heavy metal catalysts, and meets the standards of the EU REACH regulations and the US FDA food contact materials regulations. The CAB carrier itself is non-toxic and tasteless, and can be applied in consumption scenarios with high security standards, such as children's toy coatings, food packaging and printing.

Q: Can different types of CAB carriers be mixed?

A: Mixing is not recommended. Different types of CAB carriers have differences in parameters such as acetyl and butyryl content, molecular weight and viscosity, which might lead to changes in solubility, film-forming and compatibility with other components after mixing, affecting the performance stability of the final product. It is recommended to select a single type of CAB carrier according to specific consumption standards, or to conduct formulation tests under professional guidance.

Q:CAB color in the storage process need to pay attention to what matters?

A:CAB color film should be stored in a cool, dry, ventilated indoor ecological stability, prevent direct sunlight and moisture. The best storage temperature is 5-30 ℃, and the relative humidity is less than 70%. Keep the package sealed during storage to prevent moisture absorption and contamination of the color sheet. Under healthy storage conditions, the shelf life can reach greater than two years.

Q: How to judge whether the dispersion effect of CAB color film is up to standard?

A: It can be comprehensively judged by the following methods: prepare the color paste after dissolving the color chip in the solvent-based products, and detect the fineness of the color paste with a fineness scraper, requiring the reading to be below 25 microns; After preparing the coating products sample, observe whether there is graininess or orange peel on the surface; Measure the gloss and color saturation of the coating products and compare it with the expected target. Eason can provide customers with standardized decentralized effectiveness evaluation methods and operational training.