Case Study: How Ecochem Helped a South African Masterbatch Producer Solve Caking Issues When Using Light Stabilizer LS119

In the plastic masterbatch and polymer modification industry, the choice of light stabilizer plays a critical role in determining a product’s outdoor durability, processing stability, and long-term performance. Different HALS and UV absorbers exhibit different physical properties—such as brittleness, moisture sensitivity, melting behavior, and particle strength—which can significantly influence mixing, extrusion, and long-term stability.

Today’s case study comes from one of our customers in South Africa. The customer purchased a 10-kg sample of Light Stabilizer LS119 for application testing. However, during their premixing stage, they experienced caking and powder adhesion on the mixer walls, and reached out to Ecochem for technical support.

This real case illustrates how LS119 behaves under certain high-shear conditions, why the customer observed caking issues, and—more importantly—how Ecochem’s technical team analyzed the situation and proposed practical solutions. It also helps industry users better understand the characteristics and suitable applications of LS119 and UV-944.

1. Customer Background: Testing LS119 in a High-Moisture Environment

The customer is a South African manufacturer producing polyolefin masterbatch. To improve UV resistance and outdoor lifetime of their end products, they decided to test LS119, a high-molecular-weight HALS known for its excellent acid resistance.

After purchasing a 10-kg sample, they sent feedback during the trial:

“119 is quite brittle and it looks like the blades of the mixer are pulverising some of the beads during the mix, then powder compacts/cakes on the blades and sides of the mixer tank.
Could be a combination of this and moisture uptake…?”

“Not possible to take a video during mix but can take a photo at the end of the mix cycle.”

The customer also asked:

“Does LS119 enter the plastic/masterbatch industry in China or abroad extensively?”

This placed two questions in front of us:

1. What was causing the caking and powder adhesion?

2. Is LS119 widely used globally and is it the right choice for this product?

2. Ecochem’s Technical Diagnosis and Professional Response

Based on the customer’s description and experience with LS119, our team provided a detailed analysis and replied with the following points:

(1) LS119 Being “Brittle” Under High-Shear Mixing Is Normal

LS119, compared with certain other HALS, has:

• higher brittleness

• lower mechanical toughness in bead/flake form

• a tendency to generate fine powder under strong mechanical impact

In a Henschel high-speed mixer, the blades apply:

• high shear

• rotor–stator impact

• frictional heat

• mechanical collision

This environment can break the LS119 beads into powder. Once fine powder forms, it can easily:

• compact onto mixer blades

• cake on the inner walls of the mixing tank

• worsen when combined with moisture

Thus, the customer’s observation is consistent with typical LS119 physical behavior under high-shear premixing.

(2) High Humidity Significantly Increases the Caking Risk

The customer’s factory is located in a coastal region where summer humidity reaches 75%. Many HALS, including LS119, exhibit slight moisture uptake.

Moisture can cause:

• powder agglomeration

• softening and re-solidification

• caking/adhesion on metal surfaces

Thus, the combination of powder formation + moisture is a very realistic explanation for their issue.

We therefore requested a photo after mixing to evaluate the degree of moisture interaction and powder compacting.

(3) LS119 Is Indeed Widely Used Globally—But Mostly in Acid-Sensitive Applications

We confirmed to the customer:

Yes, LS119 is widely used in both China and international markets, especially in applications requiring strong acid resistance.

Typical use cases include:

• agricultural films

• greenhouse films

• outdoor plastic components

• artificial turf monofilaments (especially non-rubber-filled systems)

• PE / PP products exposed to sweat, fertilizer, or acidic environments

LS119’s chemical structure is relatively “neutral,” which gives it much better acid resistance compared with many traditional HALS.

(4) If the Customer’s End Product Does Not Require Acid Resistance, LS119 Is Not the Best Choice

Based on many years of experience, we advised the customer:

If the final application does not require acid resistance, there is no strong reason to choose LS119.

For most general outdoor applications:

• UV-944 alone already performs very well, and

• UV-944 + UV-622 is one of the most stable, industry-proven combinations worldwide.

This combination offers:

• excellent durability

• broad compatibility

• lower moisture sensitivity

• reduced caking risk in high-shear mixers

• better balance of cost and performance

We told the customer that if they could share the intended final product (film, fiber, woven fabric, injection part, etc.), we could propose a more accurate and cost-effective stabilizer system.

3. Overview of Light Stabilizer LS119: Properties and Applications

Light Stabilizer LS119 (Chimassorb 119 equivalent) is a high-molecular-weight HALS with special advantages in acidic environments.

Key Properties:

• Outstanding acid resistance

• Very low volatility

• Excellent extraction resistance

• High compatibility with polyolefins

• Suitable for long-term outdoor exposure

Typical Applications:

• Agricultural films & greenhouse films

• Outdoor PE/PP molded products

• Artificial turf monofilaments (especially non-rubber-infill turf)

• Products exposed to sweat, fertilizers, or atmospheric pollutants

• Long-lifetime PE/PP products requiring strong outdoor stability

Due to its resistance to acidic environments, LS119 is often chosen where traditional HALS might degrade or perform poorly.

4. Overview of UV-944: Properties and Applications

UV-944 is one of the most commonly used HALS in the global plastics industry. It offers an excellent balance of performance, processability, and cost.

Key Properties:

• Reliable UV stability

• Good thermal processing stability

• Low volatility

• Compatible with most PE/PP systems

• Works extremely well when combined with UV-622

Typical Applications:

• PE/PP pipe and profiles

• Outdoor plastic components

• Plastic fibers, woven bags, and geotextiles

• Films, shade nets, and agricultural covers

• Masterbatch and compound formulations

For most general-purpose outdoor applications, 944 + 622 is one of the most reliable systems used worldwide.

5. Why More Customers Choose Ecochem as Their Stabilizer Partner

This South African case highlights an important point:

Light stabilizers are not “universal.” Their performance depends on equipment, humidity, shear force, polymer type, and the final product’s environmental exposure.

Ecochem’s technical advantage lies in our ability not only to supply additives, but also to provide engineering-level support.

(1) Professional Team With Over 15 Years of Industry Experience

Ecochem specializes in:

• Light Stabilizers (HALS)

• UV Absorbers

• Antioxidants

• Polymerization Inhibitors

• Customized Additive Solutions

Our engineers understand both formulation and processing challenges.

(2) We Recommend the Best Solution for Each Customer—Not Just a Product

Our technical support covers:

• Mixing equipment evaluation

• Polymer compatibility

• Outdoor lifespan requirements

• Acid resistance vs. non-acid applications

• Cost vs. performance optimization

We always help customers choose the most suitable stabilizer system—not just the most expensive one.

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(3) Free 100–200 g Samples for Testing

To help customers minimize testing costs, we provide:

• Free 100–200 g samples

• Full technical documents (TDS, MSDS, COA)

• Application suggestions

• On-site troubleshooting support by photo/video

The customer only needs to cover the shipping cost or provide a courier account.

(4) Rich Global Case Experience Across Many Industries

We have supported customers in applications such as:

• Artificial turf

• Outdoor PE/PP film and sheet

• Agricultural films

• Shade nets and woven fabrics

• Fibers and monofilaments

• Masterbatch and compounding

• Pipes, profiles, and injection molding parts

This ensures we can give practical, proven solutions rather than theoretical advice.

6. Conclusion: Every Case Helps Us Improve Our Support and Expertise

The South African customer’s LS119 caking issue reflects a common reality in the plastics industry:

Even high-quality stabilizers behave differently under different equipment, humidity, and processing conditions.

By analyzing the mixing environment, product properties, and end-use requirements, Ecochem helped the customer:

• understand the cause of the issue

• evaluate whether LS119 is necessary

• consider alternative stabilizer systems

• identify the best formulation approach

If you also use light stabilizers in your masterbatch, outdoor products, film, fibers, or injection molding applications, we welcome you to contact Ecochem.

Our team will recommend the most suitable stabilizer system based on your product’s application—
and provide 100–200 g free samples for your evaluation.