The product made of plastic could come out from the manufacturing process with beautiful color, glossy surface and proper mechanical properties. It doesn't mean that this plastic product could be used in the outdoor application for a long period of time.
Plastic exposed to sunlight, UV, oxygen, heat and moisture could degrade and lose its color, become yellowed, chalked, cracked, lost glossiness and mechanical properties.
For example, artificial grass yarns, outdoor pipes, agricultural films, FIBC bags, outdoor furniture, automotive exterior trim parts and many other plastic products used outdoors have to face these problems, which are not just "color doesn't look nice" and which could affect the life of a product directly.
That is why the number of outdoor plastics should use UV Masterbatch.
However, UV Masterbatch is not just "adding a little bit of UV Stabilizer".
If the resin type, outdoor exposure conditions, product thickness, pigment system, adding rate and stabilizer system are not coordinated properly, the weather stability of a product could be lower than expected despite of UV Masterbatch usage.
The question here is actually:
How UV Masterbatch enhances the weatherability of outdoor plastic materials? What are the criteria for choosing the right UV system?
In this article, a systematic approach will be adopted to address how outdoor plastic materials can select the proper UV Masterbatch. The analysis will begin from the mechanism of UV aging, UV Masterbatch principle, HALS vs UV Absorber, dosage, resin compatibility, and applications such as artificial grass yarn, pipes, film, and FIBC bags.
1. Why Do Outdoor Plastics Age Easily?
2. What Exactly Is UV Masterbatch?
3. How Does UV Masterbatch Improve Weather Resistance?
5. Same 3% UV Masterbatch, Different Results
6. How Much UV Masterbatch Should Be Added?
7. Why Product Thickness Matters
8. Why Color Affects Weather Resistance
9. Black Masterbatch and Weather Resistance
10. Why the Carrier Resin Matters
15. Color Fine, Performance Dropped
16. How to Test the Actual Effect
17. "Years of Weather Resistance" Claims
19. How to Choose a Suitable UV Masterbatch?
Outdoor aging of plastics is not always the result of a single reason.
Under the real conditions, plastic can be affected by various reasons simultaneously:
UV rays
Oxygen
Heat
Moisture
Rain
Thermal cycles
Pollutants
Mechanical stress
Among all, the UV radiation is often one of the significant reasons for the photodegradation of polymers.
The rays from the sun can cause photochemical reactions in certain molecules of the polymer chains. It leads to the generation of free radicals causing further oxidation reactions.
As the aging process proceeds, it may result in:
Polymer chain breaking -> surface oxidation -> discoloration -> embrittlement -> crackings -> decreased mechanical properties
Thus, the initial phase of the outdoor plastic can be represented by discoloration. Further, under the influence of various factors, it can eventually turn out to be:
Decreased tensile strength
Decreased elongation at break
Decreased impact strength
Cracks on the surface
Chalking
Brittle cracking
And this is why Weather Resistance cannot be assessed solely based on "discoloration."
UV Masterbatch is a functional masterbatch that can make the light stabilization systems of UV Stabilizer, UV Absorber, and HALS into a masterbatch with the appropriate carrier resin and process technology.
The primary objective of UV Masterbatch is to deliver the light stabilizers into the polymer system in a better and controlled manner while processing plastics.
Compared to the addition of additives in powder or liquid form, UV Masterbatch often provides the following benefits:
Easier dosing
Easier blending
Easier storage and transportation
Easier dispersion control
More suitable for continuous manufacturing
Easier to combine with other masterbatches
However, there is one thing that should be taken into consideration in particular:
UV Masterbatch is not a definite formulation.
Each product uses a different combination of:
HALS
UV Absorber
Antioxidant
Carrier Resin
Stabilizer Combination
Therefore, "UV Masterbatch" does not necessarily mean that this product will be suitable for your outdoor application.
What really counts is the kind of stabilization system that the product incorporates and its compatibility with your resin and outdoor conditions.
By knowing how UV Masterbatch works, one will understand how different UV systems may have different impacts on their own.
Popular UV stabilization systems usually consist of:
1. HALS
"HALS" is short for Hindered Amine Light Stabilizers.
The HALS system does not act as a blocker of the UV light. It functions mostly by capturing the free radicals generated during photo-oxidation reaction and preventing photo-oxidative degradation of the polymer.
It means that HALS system is very essential for outdoor plastics.
2. UV Absorber
UV Absorber is known as the ultraviolet absorber.
It absorbs the ultraviolet rays in the given wavelength range and converts them into less harmful energy. In this way, the effect of ultraviolet rays on the polymer is reduced. Some products require UV Absorber because of their transparent or light color.
3. Antioxidants
Antioxidants are primarily used to prevent the occurrence of oxidation reactions that occur during processing and application.
In a real outdoor system, light stabilizers and antioxidants are not a fully substitutable combination.
Some applications should take into account the following:
UV Stabilizer + HALS + Antioxidant
as a joint system.
This is a very common question from customers when choosing a UV Masterbatch.
It can be simply understood as:
| Type | Main role | Typical features |
|---|---|---|
| HALS | Inhibits free radicals, slows down photo-oxidation | Very important for long-term weather resistance |
| UV Absorber | Absorbs UV energy | Reduces the direct action of UV on the polymer |
| Antioxidant | Inhibits oxidation reactions | Helps with processing and long-term stability |
However, in practice, it is not just "HALS is always better than UV Absorber."
Different resins, colors, and product structures may require different demands on the stabilizer system.
Such as:
PE outdoor products，PP artificial grass yarn， TPU outdoor film， PET fiber， PC outdoor products
Their light stabilization requirements are not exactly alike.
Therefore, it is recommended to consider all the following factors at once when selecting UV protection system: resin, color, thickness, outdoor environment, and targeted service life.
This is one of those questions which come very easy while testing.
Customer can say:
"The addition rate for Supplier A is 3% and Supplier B is also 3%. Why is the weather resistance result so much different?"
Because in reality, what counts here is not the figure of "3%". But,
Active ingredient x concentration x dispersion x compatibility x application
Like this,
UV Masterbatch from Supplier A might have more active ingredient, but not a good carrier.
While from Supplier B, the addition rate might look higher, but their stabilizer system will match the customer's resin.
The outcome could be exactly opposite.
Therefore:
Ratio of UV Masterbatch cannot be considered without active ingredient and application.
Many customers hope to get an extremely straightforward answer:
"Should I add 1%, 2%, or 3% of UV Masterbatch?"
There is actually no universal percentage that can apply to all kinds of plastics.
The correct percentage should depend on:
Basic Resin
Product Thickness
Outdoor Exposure Time
Service Life
Intensity of UV
Weather Condition
Pigments System
Type of Stabilizer
Required Performance
In general, common outdoor applications of plastics can adopt a smaller percentage. High UV exposure time, long outdoor usage period, or high-performance plastic products may require a larger amount of stabilizer added.
A more rational approach should be:
Set the weather resistance standard first, and then trace back to the UV system and percentage.
Not start with "should add 2%" first.
It is an aspect that is frequently overlooked.
Same resin and same UV masterbatch
0.05 mm thick film
And
3 mm thick injection molded part
Do not have the same exposure to UV radiation.
Film has high Surface to volume ratio. Also, the entire material layer can be more prone to light.
So,
For
Agricultural Film
Outdoor Film
Thin sheet
Fiber
And many other thin wall applications, the UV system has to be more cautious.
For thick wall applications, you also have to take into consideration
UV penetration
Surface degradation
Long term diffusion
Intrinisic Stabilizer distribution
So, you cannot use "One Formula + One Addition Ratio" for all thicknesses.
This is an extremely important issue in cases where both Color Masterbatch and UV Masterbatch are simultaneously applied.
Different types of pigments vary in terms of light absorption, reflection and stability to UV.
For instance:
White
Yellow
Red
Blue
Green
Black
may behave completely differently after the product is exposed to outdoors.
Particularly when it comes to light-colored products, fading and yellowing are more noticeable.
In black products, despite the fact that the "fading" effect is not visual, the resin may experience photo-oxidation and deterioration of mechanical properties.
Thus:
Both Color Masterbatch and UV Masterbatch should be considered together.
It is impossible to assume that "UV Masterbatch is already there, and thus any color will have equal weather resistance."
Carbon Black is a unique example.
For many outdoor applications such as PE, the appropriate carbon black system will give an effective UV protection.
That is why many:
PE Pipe
Agricultural Products
Cable Duct
Outdoor Containers
use black system.
However, it should be noted that:
Not all black masterbatches can become a high weather resistant black masterbatch automatically.
The outdoor black system still requires attention to:
Type of Carbon Black
Content of Carbon Black
Dispersibility
UV Resistance
Resin Base
If there is poor dispersion of carbon black, it can affect the end result.
The Carrier Resin in the UV Masterbatch can influence the dispersibility and compatibility of the stabilizer in the base resin.
For instance:
PE application → carrier PE-compatible
PP application → carrier PP-compatible
TPU application → carrier TPU-compatible
PET application → carrier PET-compatible
PA application → stabilization system PA-compatible
In case the carrier system is chosen improperly, the following can be observed:
Stability issues
Migration
Exudation
Processing difficulties
Surface problems
Hence, in case of outdoor applications having high requirements, using only one universal UV Masterbatch is not an option.
If the client clearly states to the supplier:
"Our product is PP artificial grass yarn."
The supplier must select the stabilization system in relation to the PP resin and the spinning process.
Artificial turf is an extremely common outdoor UV application.
Artificial Turf is generally expected to last for a long period of time under conditions such as:
Sunlight
UV radiation
Rain
Heat
Changes in temperature
While it also requires maintaining:
Color stability
Tensile strength
Flexibility
Surface condition
In particular for artificial grass yarns in colors such as green and brown, the obvious fading due to sunlight exposure will directly impact the aesthetics of the turf.
Thus, in general, the UV Masterbatch of the Artificial Turf has to be tested alongside the Color Masterbatch.
Not only the color fading test result matters but also you should concentrate on:
Tensile strength + Elongation + Color change + Surface condition
PE Pipes are also a common example of this.
Outdoor water supply pipes, irrigation pipes, drainage pipes, and other outdoor PE products might be under exposure to sunlight for a relatively long period of time.
Therefore, you should take into account:
UV Resistance
Weathering Resistance
Long-term Mechanical Stability
Color Stability
In the case of black PE pipes, you could utilize a proper carbon black system together with a UV stabilization system.
For non-black pipes such as blue and white pipes, you have to be aware of the compatibility of the UV Masterbatch and the Color Masterbatch.
In the case of white products especially,
The interaction among TiO2, UV Stabilizer, resin, and processing conditions could all influence the weather resistance.
"Agri-Film" is a common long-term outdoors film.
It might be needed to endure:
Very strong sunlight
Extreme heat
Moisture
Pesticides or chemicals
Long-term continuous usage
Thus, the UV stabilization for agricultural film is not merely "increasing the amount used".
But it should take into account:
Film thickness
Polymer type
Film lifetime
Compatibility of additives
Reaction with pesticide
Processing temperature
In particular, pesticides and chemicals in the agri-environment may have a negative effect on some stabilizers in the long run.
Thus, the actual recipe better to be tested in the given environment.
There will be a requirement of particular storage and transportation ability for FIBC, bulk bags and PP woven bags.
Apart from the color retention properties, there may also be concerns of:
Tensile Strength
Elongation
UV resistance
Life in Storage
Fabric strength
The UV aging characteristics of PP woven fabric after tape drawing and weaving process are different compared to normal injection molding process.
Therefore, in selecting the UV Masterbatch, you should take into consideration:
PP compatibility + Spinning Stability + Dispersion + Outdoor Durability
and not directly use any regular injection grade UV masterbatch.
This is a point worth making when testing weather resistance.
Some products, after exposure to a certain level of UV:
Color still looks good visually.
However,
Decrease in tensile strength
Decrease in elongation
Decrease in impact strength
may already be observable.
This means:
Color Retention ≠ Weather Resistance
Testing weather resistance should take into account at least:
Appearance
Change in Color
ΔE
Gloss
Cracking
Chalking
Mechanical properties
Tensile Strength
Elongation
Impact Strength
Surface Properties
Cracks
Powdering
Surface Defects
Products that require more rigorous testing cannot rely on ΔE only.
However, when comparing two suppliers of UV Masterbatch, do not rely solely on the TDS provided by the supplier.
One could follow the following testing procedure.
Step 1: Verify the Base Resin
Ensure that different samples have the same:
Resin Grade
Resin Batch
Color Masterbatch
Step 2: Standardize the Addition Ratio
For instance:
1%
2%
3%
The gradient should be set depending on the actual project.
Step 3: Standardize the Processing Conditions
Such as:
Temperature
Screw Speed
Residence Time
Cooling Conditions
Step 4: Carry out the UV Exposure
Depending on the use of the products:
UV Aging
Xenon Arc
QUV
DIN-related tests
ISO-related tests
Step 5: Test the performance before and after aging
It is advisable to test the following:
ΔE + Tensile Strength + Elongation
In addition, for some products one may test the following:
Impact
Surface Cracking
Gloss
Appearance
The results obtained through this procedure will be much more relevant than just "UV masterbatch added at 2%."
Questions that customers usually have:
"Is this UV Masterbatch able to guarantee 5 years?"
The truth is that this statement ignores many variables.
Since the "5 years" is depending on:
What country
Climate
UV intensity
Outdoors exposure
Product thickness
Product color
Resin
Stabilizer system
Real dosage
Outdoor conditions of the southern US, Southeast Asia, Middle East, north of China, and Europe are quite different from each other.
Therefore, the more appropriate way of saying it should be:
Assess based on specific test condition and target environment, instead of making guarantee on a number of years.
