Metallic basecoats are widely used on automotive parts, hardware, aluminum alloy, stainless steel, electronic accessories and metal decoration. Formulators constantly seek resin combinations that deliver brilliant metallic appearance together with stable construction performance and long-term outdoor durability.
Blending Cellulose Acetate Butyrate (CAB powder) with thermoplastic solid acrylic resin has become a mature, high-performance formula solution for premium solvent-borne metallic paint. This resin combination overcomes many common defects of single acrylic resin systems and balances aesthetic effect, processing efficiency and coating protection.
1.Perfectly improve the orientation effect of aluminum flakes, delivering a more transparent, high-glitter metallic finish without mottling defects
The core quality of metallic paint depends on the flatness of the oriented arrangement of aluminum silver powder and pearlescent pigments.
Metallic paint prepared with pure acrylic resin exhibits single rheological behavior and slow solvent release. After spraying, aluminum flakes tend to float randomly, causing mottling on vertical surfaces, whitish appearance from the front and dark shade from the side, resulting in poor metallic layering and low production yield.
After adding CAB cellulose acetate butyrate powder, the rheological property of the system is precisely regulated:
During the solvent volatilization of the wet spray film, CAB guides metallic pigments to lay parallel and flat on the substrate surface, forming a uniform and dense oriented arrangement.
This brings remarkable effects：
- 1. Enhanced mirror-like metallic luster and higher gloss
- 2. Distinct flop effect, with three-dimensional and advanced color difference between front and side views
- 3. Thoroughly eliminates coating defects such as mottling, floating color, foggy whitening and speckling in metallic paint
- 4. High spraying tolerance; consistent appearance can be maintained even with minor fluctuations in spraying air pressure and film thickness
II. Significantly improved drying speed, effectively solving sagging and dust pickup issues.
During mass spraying on automated production lines, slow drying of the wet film easily leads to construction defects including vertical sagging, dust particle adhesion, sticking contamination and piled orange peel, which seriously impairs production efficiency.
CAB cellulose features excellent solvent release capacity. When compounded with acrylic resin:
- Flash-off speed is greatly accelerated, and the wet film sets rapidly
- Outstanding sag resistance for vertical spraying
- Shortened spraying interval, suitable for continuous operation on production lines
- Less tendency to blushing, milking and water-induced gloss loss when applied in high-humidity environments
III. Excellent anti-lifting and anti-bleeding properties, suitable for the two-layer system of metallic base coat + clear topcoat
Most metallic paints adopt a two-coat process consisting of a metallic base coat and a transparent clear topcoat.
The CAB-acrylic composite system forms a dense and compact film structure, creating an effective solvent barrier layer:
- Effectively resists solvent erosion from the upper clear coat
- Preserves the oriented arrangement structure of metallic pigments
- Eliminates interlayer defects such as blistering, wrinkling and delamination
- Delivers excellent interlayer adhesion, and the composite film is full and transparent as a whole
IV. High storage stability of finished products, with no stratification, turbidity or yellowing tendency
Traditional NC nitrocellulose metallic paints have obvious drawbacks: prone to hydrolysis, poor yellowing resistance, short shelf life and easy precipitation and agglomeration.
In contrast, the system of CAB cellulose combined with solid acrylic resin powder boasts prominent advantages:
- 1. Excellent resin compatibility, with no stratification, precipitation or coarsening after long-term storage
- 2. Superior hydrolysis resistance, extending the shelf life of finished paint products
- 3. Far better UV resistance and yellowing resistance than the NC system, making it ideal for outdoor metal coating applications
- 4. Stable viscosity with minor formula fluctuations across seasons
V. Balanced film performance: high hardness, good toughness and outstanding weather resistance
The film formed by pure acrylic resin is relatively hard and brittle, prone to cracking during bending and chipping upon impact.
A single cellulose system is overly soft, with insufficient wear resistance and scratch resistance.
The combination of the two achieves complementary and balanced performance. Acrylic resin provides high hardness, strong adhesion, weather resistance, gloss retention, wear resistance and scratch resistance, while CAB cellulose delivers flexibility, impact resistance, crack resistance and levelling property.
The final coating film features:
- 1. No fading or gloss loss after long-term outdoor exposure
- 2. No chipping during workpiece bending and stamping
- 3. Excellent stability against thermal cycling of hot and cold temperature differences
- 4. Retains a brand-new appearance for hardware and automotive parts after long-term use
VI. Wide substrate versatility and stable adhesion to various metal substrates
The CAB-acrylic resin system exhibits excellent wetting performance and strong compatibility with a wide range of metal substrates:
- Cold-rolled steel sheets and iron hardware
- Aluminum alloys and aluminum profiles
- Stainless steel and galvanized sheets
- Zinc alloys and die-cast metal components
- Metal housings for 3C electronic products
VII. Strong formula adaptability, enabling the production of high-solid, low-VOC environmentally friendly metallic paint
With the upgrading of environmental protection requirements for coatings, low-odor, high-solid and low-VOC metallic paint has become an industry trend.
The composite system of CAB cellulose and solid acrylic resin:
- Is compatible with various mixed solvents including aromatic hydrocarbons, esters and ketones
- Supports high-solid formula design to reduce the dosage of diluents
- Features lower odor and less pollution, meeting environmental production standards
