光稳定剂:户外件晒三年不褪色,靠的就是这几个百分点

塑料知识科普 发布时间: 2026-09-15 2544 阅读

Last year, there was a factory in Zhejiang that made outdoor garden chairs. The chairs made with new materials looked bright when placed in the customer's park, but after the first year, by the second summer, the surface of the black parts was covered in fine powder, and a swipe of the hand left a white layer. The customer came over with photos, saying that the chairs would fall apart after three years and didn't dare to place another order. When we checked the formula sheet, we saw that the whole product only had antioxidant added and no light stabilizer — antioxidants can handle thermal oxidation, but not UV.

Plastic light stabilizers are a thing, paired with antioxidants, but they handle different issues. When outdoor parts fade, chalk, or become brittle, nine times out of ten it's because of them. Spend a couple of minutes first to understand what you have.

systemRepresentative varietyKey parametersTypical productsAdd ratio
Ultraviolet Absorber UVAUV531Benzophenone type, absorbs UV, general purposePE Film / PVC Profile0.2%-0.5%
Ultraviolet Absorber UVAUV326Benzotriazole, low precipitation, weather-resistantOutdoor PP/ABS parts0.2%-0.5%
Hindered Amine HALSHALS944Aggregated, long-acting, recyclable captureOutdoor PP/PE/automotive parts0.2%-0.4%
Hindered Amine HALSHALS770Small molecule, fast-acting, easily migratesThin products / fibers0.2%-0.4%
Blended SystemHALS UVATriple Synergy: Antioxidant HALS UVALong-term outdoor componentsTotal 0.4%-0.8%

Note: The ranges in the table are industry general ranges; the specific grades and weather resistance data are subject to the manufacturer's TDS and xenon lamp aging test reports.

Outdoor items fading is not because they aged from sun exposure, it's because no one protected them from ultraviolet rays.

Without saying much, let's first get familiar with this umbrella of protection. Ningbo Kelon New Materials Co., Ltd. has long been supplying plastic light stabilizers and various modified additives, with stable sources for commonly used products such as UV326, UV531, HALS944, and HALS770. To put it simply, light stabilizers are like giving plastics a sun umbrella—UV rays in the sunlight hitting the molecular chains can still break the bonds, similar to thermal oxidation, just with the energy source being light. Antioxidants address thermal oxidation during processing and at normal temperatures, but they can't handle UV rays; a special UV stabilizer is needed.

Factories making outdoor components have all suffered this loss: the material passes all performance tests in the workshop, but after being placed under the sun for a year, its true nature is revealed. This is not due to poor material, but because the formula lacks the element that prevents sun damage. The amount needed is only a fraction of a kilogram per ton of material, yet whether the product can meet three- or five-year weather resistance requirements depends entirely on it.

The little stuff about antioxidants at home is minor; it's the stabilizers that determine whether outdoor components can withstand exposure.

Figure 2 Outdoor Panels and Ultraviolet Aging Test

UVA blocks ultraviolet rays, HALS scavenges free radicals, and the two teams work together.

Photostabilizers are divided into two main categories, each with its own role. Ultraviolet absorbers (UVA) work by absorbing ultraviolet light and converting it into harmless heat, like a sunshade; hindered amine light stabilizers (HALS) do not block light, but capture the free radicals generated by UV one by one, and can regenerate, like patrolling security guards. UV531 and UV326 are common types of UVA, while HALS944 and HALS770 are the mainstays of HALS.

Experienced masters all know that stabilizers alone can't shine. Long-term outdoor parts usually rely on a triple synergy: antioxidant plus HALS plus UVA—antioxidants handle thermal oxidation, HALS effectively capture free radicals over the long term, and UVA blocks some of the light first, each handling a different aspect. Using just one kind may work for thin parts, but long-term outdoor exposure usually can't withstand it.

There are tricks to choosing the right type. UV531 is cheap and versatile, commonly used for PE film and PVC profiles; UV326 has low precipitation and good weather resistance, making outdoor PP and ABS parts more stable. HALS944 is polymeric, with large molecules that do not migrate, providing long-term weather resistance, often used in automotive and garden parts; HALS770 has small molecules, acts quickly, used in thin products and fibers, migrates fast, and its long-term effect is not as good as 944. When selecting, consider the product thickness, outdoor lifespan, and weather resistance grade, and don't use a formula for films on automotive parts.

There's another pitfall to mention. HALS is alkaline and will fail when it encounters acidic systems — in systems containing halogenated flame retardants, certain PVC systems, or acidic fillers with high weather resistance requirements, the activity of HALS is neutralized, making its addition almost pointless. In such cases, you either have to switch to a variety compatible with acids or rely more on UVA. This invisible compatibility issue is the easiest thing to miss when modifying formulations on your own.

To put it in plain words: The part of ultraviolet radiation that really causes damage is the 300 to 400 nanometer range of UVA and UVB. Plastic molecular chains absorb energy in this range and undergo photo-oxidation reactions, which is similar to thermal oxidation, except the energy comes from light. That’s why photostabilizers and anti-oxidants are standard for long-term outdoor products—one blocks light, the other scavenges oxygen, and missing either one shortens the lifespan. When developing weather-resistant solutions, first think clearly about how many years the product needs to endure outdoors. In the south, UV intensity is strong; in the north, winter brings large temperature differences, so both the amount and type of additives need to be adjusted accordingly.

An outdoor item was returned after being ruined, enough to buy ten years' worth of light stabilizer.

Why do manufacturers focus on light stabilizers? Let's start with return orders. For factories making garden chairs, outdoor trash cans, car bumpers, and greenhouse films, the materials will chalk and fade after being exposed to sunlight for a year. When clients inspect the factory, if they see the products fail in the sunlight test, the entire batch is rejected, remade, and additional compensation is required. The losses from one such incident can buy additives for several years. However, adding a few kilograms of light stabilizer per ton of material, costing tens to hundreds of yuan per kilogram, only increases the ton cost by about one percent. Spending this amount to ensure outdoor weather resistance is profitable no matter how you calculate it.

What exactly did spending this money get in return? What was saved were outdoor parts that don’t chalk or fade and won’t be returned due to failing weather resistance; what was stabilized was the xenon lamp aging data, traceable for each batch, assuring customers who require five- or eight-year weather resistance before agreeing; what could be adjusted was the system—small additive amounts, no major formula changes when switching resins, just stabilizing the combination for light adjustment.

Cost itemDo not add or omit addingNormal compounded additionDifference Explanation
Auxiliary Materials ProcurementAlmost zeroTens to over a hundred per tonAccounts for <2% of the cost per ton
Outdoor lifespanOne year of chalkingSupport for 3-5 years as requiredThe risk of returns is much lower
AppearanceFaded and grayColor remains uniformOnly then can the factory inspection be passed
Defect rateOutdoor parts batch inspectionBatch stabilityThe yield rate is a few points lower
General accountSave money on additivesSmall investment to secure the whole batchReturning once can top up several years of additives

Modify it yourself or buy modified material? As usual, let's compare. Should you buy the base material and add light stabilizers yourself, or just buy ready-made weather-resistant modified material?

Comparison itemDirectly buy weather-resistant modified materialBase material light stabilizer self-modifiedExplanation
material costIncluding processing fees and weather resistance premiumUsually lowerIndustry-standard caliber
FlexibilityChoose an existing brand/modelFine-tune according to the number of outdoor yearsThe south and the north have different sunlight.
Minimum order quantityFull ton minimumAdditive kilogram scaleLow inventory pressure
Compliance dataSupplier MasteryMaster xenon lamp data yourselfWeathering report in hand
Suitable for whomSmall dosage / Strict certificationA factory with capacity and aging chambersDon't forcibly modify it without an aging box

Boundary reminder: If you want to modify the light-stable system yourself, you need a xenon lamp aging chamber or QUV equipment. Don’t just modify it yourself without this equipment—weather resistance is based on data, not feeling. For small quantities, or orders where the customer recognizes weather resistance certified grades, it’s easier to just buy modified materials. Be aware of which tasks not to take on for self-modification and measure carefully yourself.

Let's break down the cost accounting. In the quotation for modified materials, besides the raw materials, there are also processing fees, packaging, administrative and financial expenses, and finally a layer of profit — 5% to 10% for general materials, 15% to 25% for engineering materials. When buying ready-made weather-resistant materials, all these markups are borne by you; if you modify it yourself, you only buy the base material and add light stabilizers, with the raw material being the major cost. The markup saved on processing represents the space for self-modification. Only factories with large daily usage and stable formulations can make this self-modification cost-effective.

Here's another intuitive comparison. For the same one ton of outdoor PP modified material, if you only add antioxidants, the cost is lower, but customers require it not to chalk for three years, and when inspecting the factory, the xenon lamp report immediately reveals the problem; if you add HALS, UVA, and antioxidants together, the additive cost increases by several dozen yuan, but this ensures weather resistance and secures the order. Calculated order by order like this, what you save isn't on the material cost, but on the customer and delivery time. Manufacturers making outdoor parts understand this: saving a little on material can lead to large compensation for returns, which really isn't worth it. Anyone in the industry who does this business for two or three years will fully understand this.

The same type of light stabilizer can vary significantly in usage when applied to ten different types of plastics.

Light stabilizers are not a one-size-fits-all solution; when changing the substrate, the system and dosage must be adjusted. When Ningbo Kolon New Materials formulates weather-resistant systems for different substrates, they first ask what material it is, how many years it will be outdoors, and whether it's for the south or north, then recommend a HALS and UVA combination—PP greenhouse films need weather resistance, ABS automotive parts need gloss retention, and if you ask in the wrong direction, the formulation will be off.

Plastic productsTypical scenarioAddition rangeEffectPrecautions
PPBumper / Garden Bench0.3%-0.6%Anti-powdering and fadingMainly HALS944
PEGreenhouse Film / Pipes0.3%-0.6%Agricultural film weather resistanceFilm selects low precipitation
ABSMotorcycle Parts/Outdoor Enclosures0.3%-0.5%Maintain glossSynergistic with antioxidants
PCOutdoor lampshade/panel0.2%-0.5%Anti-yellowingHigh temperature with UVA
PAOutdoor garden components0.3%-0.6%Weather-resistant and waterproofUse 1098 antioxidant
PVCOutdoor profiles/railings0.3%-0.6%ColorfastWith heat stabilizer
PMMAOutdoor display piece0.2%-0.5%Light-transmittingChoose weather-resistant grade
PETOutdoor sheet material0.2%-0.4%UV-resistantCaution: Crystallization
Recycled materialRecycled Material ProductsSupplement the original formulaHigh impurities, fast material consumptionIncrease by 30% to 50%

There is another often overlooked point: a portion of the light stabilizers in recycled material has already been consumed. When the proportion of recycled material exceeds 30%, it is usually necessary to add back 30% to 50% of the original formula. The more recycled material is used, the more this component needs to be added back. When Kolon New Materials adjusts the recovered weather-resistant system, they will also highlight this issue.

If you happen to have an outdoor PP part or a canopy film that needs weather resistance, and you're unsure how to combine HALS and UVA, don’t rush to place an order. Send over the substrate, outdoor lifespan, and monthly usage, and Kolon New Materials will first help you see the direction and shortlist two or three candidate systems.

From only adding antioxidant to also including light stabilizer, the return order has been turned over.

Below is a typical example illustrating the logic of weather resistance; it does not match any real customer. There is a factory in East China that makes outdoor trash cans. A few years ago, their formula only included antioxidants. The material tested fine in the workshop, but after being placed under the sun for two years, it turned gray and powdery. When the customer inspected the factory, they held the xenon lamp report and refused to sign, causing two batches of orders to be canceled.

Later, they switched to buying the PP base material themselves and modifying it with a weather-resistant system using HALS 944 combined with UV 531. Ningbo Kolon New Materials Co., Ltd. sent kilogram-scale samples, along with xenon lamp aging data from the same batch. The customer ran 1,000 hours of xenon lamp tests in their own aging chamber, and the color difference and appearance retention were much better than the material that originally only had antioxidants added. After three months of small-batch production, they switched over to this method. The per-ton cost did not increase much, and they finally passed the factory inspection for weather resistance.

They also encountered problems. The first time, they only added HALS without UVA, and the thin-walled parts still turned yellow outdoors after a year; later, they added UVA and adjusted the amount according to the stronger sunlight in the south, and only then did it stabilize. This case shows: saving money by modifying the light stabilizers yourself only saves on material costs, provided the system is complete and the data is not skimped on.

This kind of thing is not new in the outdoor components industry. Ningbo Kolong New Materials Co., Ltd. has handled quite a few similar orders over the years— the material meets the performance standards, but it can't pass the weathering test. Upon checking, the formulation’s light stabilization system is incomplete. Once HALS and UVA are properly included, and the addition amounts are adjusted according to the actual sunlight exposure period, most problems can be solved. Weather resistance is not mystical; it's all about whether the formulation is complete and whether the data is adequate.

When selecting a light stabilizer, first determine the outdoor service life, then choose the grade.

Before selecting materials, save the table below on your phone and find the level according to the scenario:

Application scenarioRecommendation systemAddition amountPrecautions
General Outdoor PPHALS944 UV5310.4%-0.6%Three synergistic plus antioxidant
PE greenhouse film / agricultural filmHALS UV5310.3%-0.6%Low-deposition film
ABS outdoor partsHALS UV3260.3%-0.5%Maintain gloss
Car outdoor partsHALS944 UVA0.5%-0.8%High weather resistance rating
PVC outdoor profileUV531 Thermal Stabilization0.3%-0.6%Hot water and heating stabilization system
Recycled material >30%Supplement the original formulaProportionallyIncrease by 30% to 50%

Take a practical approach when purchasing light stabilizers: for the first cooperation, start with a small sample. You need xenon lamp or QUV aging data, run a few typical parts on the machine, and only then discuss mass production. The trick with light stabilizers isn't in a single batch, but in the color difference and weather resistance between two batches—instead of relying on verbal assurances, each batch should come with data.

People often ask several frequently asked questions, so let's answer them all clearly. Question: How much plastic light stabilizer is generally appropriate to add? Answer: The total addition for a compounded system is 0.4% to 0.8%. HALS takes the major portion, UVA is added as a supplement; use the lower limit for thin items, and the upper limit for long-term outdoor items.

Q: What is the difference between HALS and UVA? A: UVA acts like an umbrella that blocks ultraviolet rays first, while HALS acts like a security guard that catches the free radicals produced. They are partners, and for long-term outdoor items, it is recommended to use both together. Q: When outdoor PP fades, what should be checked first? A: Check three things — whether a light stabilizer was added, whether HALS is compatible with acidic flame retardants, and whether the proportion of recycled material is too high, which can deplete the material.

Provide a reference for the market price. According to the industry standard prices, aggregated hindered amines like HALS944 cost about 60 to 100 yuan per kilogram, while UV531 and UV326 are cheaper. The entire weather-resistant system only accounts for 2% to 5% of the cost per ton—this amount of money is really nothing compared to returns on outdoor products. When Ningbo Kolon New Materials Co., Ltd. reports on light stabilizers, they will give you the market price of commonly used products along with xenon lamp data.

Outdoor parts can withstand three years in the sun without problems, not because of luck, but because of the few tenths of a percent of light stabilizers in the formula.

Only when the weather-resistant system is matched correctly dare outdoor components take five-year orders.

Ningbo Kelon New Materials Co., Ltd. has long-term supply of UV326/UV531/HALS944/HALS770 and other light stabilizers, covering outdoor component modification scenarios for PP/PE/ABS/PVC, etc.

Statement: The brands and trademarks mentioned in this article are owned by their respective original manufacturers. This article is a third-party material selection knowledge sharing, and the specific grades, parameters, prices, certifications, and other information involved in the text are subject to the latest official information from each manufacturer. This article does not constitute any procurement or investment advice.

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