再生PC聚碳酸酯:板材掺混都在用,性能衰减没你想的那么狠

塑料知识科普 发布时间: 2026-09-15 4635 阅读

There is a type of material where the new version is so expensive it hurts, yet the recycled version is quietly sent back to its original position—the transparent sheet is still that sheet, the casing is still that casing, and no one can tell whether it is new or old. This is recycled PC, polycarbonate. This article explains it thoroughly: why the transparent grade is so precious, where blending grades save costs, whether performance degradation can really be tolerated, and how to choose between making transparent parts and non-transparent parts.

Let's spend two minutes getting to know the main character. Ningbo Cologne New Materials Co., Ltd. is an integrated trade and industry supplier of plastic raw materials. Recycled PC is a regular category, and it comes in multiple grades: transparent grade, blend grade, and modified grade. PC, or polycarbonate, is known for being transparent, impact-resistant, and heat-resistant, and it is used in safety helmets, CDs, phone cases, car lights, sunlight panels, and electronic housings. The sources of recycled PC are mainly waste transparent sheets, appliance housings, water bottles, and lampshades, which go through sorting, crushing, cleaning, and granulating. The technical basis is GB/T 40006.7-2021 "Plastics — Recycled Plastics — Part 7: Polycarbonate (PC) Materials," which clearly outlines the indicators and testing methods for recycled PC.

First, let's briefly clarify the nature of PC. It has high light transmittance, similar to glass, but is much lighter and won't shatter; it is heat-resistant, dimensionally stable, and a good electrical insulator, which is why electronic housings, safety helmets, car lights, optical discs, and phone cases all compete to use it. Also, because transparent parts require high impact resistance and optical performance, new PC is expensive. Saving a piece while making a part makes cost-sensitive manufacturers naturally turn to recycled material. This is where the value of recycling lies: a piece of transparent PC that has been used for more than ten years may have slightly reduced optical performance, but its foundation is still intact. After cleaning and granulating, it can be used for opaque or semi-transparent parts, making full use of the material. The valuable performance stays where it is needed, instead of going to the landfill with waste — keeping good material in the loop is what makes this business legitimate.

New PC material is painfully expensive, while recycled PC is quietly returning to its original manufacturers

PC is the 'high-priced child' among engineering plastics. It has good transparency, high impact resistance, and stable dimensions, and a ton of new material is often more expensive than general plastics. The value lies here: when making a transparent sun panel, customers want it to be light-transmitting, impact-resistant, and resistant to yellowing for ten years. Such precious material is too valuable to just throw away after use, so recycling it for reuse is only natural. Recycled PC is essentially 'returning home'—sheets go back to sheets, housings go back to housings, rather than being downgraded into completely unrelated products.

GB/T 40006.7 has very detailed requirements for recycled PC: the MFR report must provide measured values and the coefficient of variation must be controlled; both cantilever and simply supported beam notched impact strengths must be measured; tensile strength and bending strength have specified ranges; for transparent materials, light transmittance and yellowing index must also be monitored. In the publicly available test data, well-produced transparent recycled PC can achieve a light transmittance of about 89% with very low haze, keeping the gap with virgin material within a single-digit percentage. This indicates one thing: cleanly sorted and properly processed recycled PC does not experience performance degradation as drastically as outsiders might think.

So why do some people say that recycled PC turns yellow and becomes brittle after use? It's because the degradation of PC carries a 'historical burden.' It absorbs moisture, so if it's not dried before processing, it undergoes hydrolysis; it is sensitive to repeated heating, with each pass through the extruder breaking some molecular chains, raising the MFR, and shifting the color toward yellow; during the recycling process, metal ions like iron or copper may also be mixed in, accelerating degradation. The instability of recycled PC often doesn't start from zero, but carries the damage from its previous use and processing when re-entering the furnace. Understanding this, you'll realize that the problem isn't with the word 'recycled' itself, but with 'how many times it has been recycled, whether it has been dried, and whether the sorting is clean.'

Breaking down the degradation, there are mainly three factors: The first is hydrolysis. PC naturally absorbs moisture, and if the material is not dried before entering the extruder, the moisture will break the molecular chains when heated, causing silver streaks and strength loss. The second factor is thermal-oxidative aging. Repeated heating and exposure to light create yellow chromophores in the material, making it progressively yellower, and it will continue to change in the next processing. The third factor is contamination. Trace metals like iron and copper introduced during recycling, crushing, and transportation, although minimal, can quietly accelerate degradation. To counter these, every step—washing, drying, temperature control, and avoiding light—helps restore the material. If done well, performance degradation slows down; if neglected, even new material can't be saved.

Recycled PC isn't afraid of being used; what it fears is carrying a bunch of old damages and being thrown into the furnace by you for the third time.

Figure 1  Scene of recycled PC granules and transparent sheets (schematic diagram)

Transparent grade is valuable because it doesn't yellow, mixed grade is economical because it's not picky about the surface.

The grade of recycled PC is essentially divided based on 'whether it can be transparent.' The transparent grade requires the raw materials to be clean and transparent sheets or pieces, without color or yellowing; after granulation, they should have high light transmittance and a low yellowing index. This grade is expensive because sources of transparent material are scarce and sorting is strict. The natural color grade is used for electronic housings and safety helmets; it requires color matching and impact resistance, but transparency is not required. The blended grade simply does not pursue transparency; various sources of PC are mixed to make modified materials, which are cheap and practical, used for mixed panels and non-transparent structural parts.

The process of recycled PC has two main challenges: first, it must be thoroughly dried because PC absorbs moisture, and if the water content is too high, it will hydrolyze, develop silver streaks, and lose strength during processing; second, the processing temperature and the number of times it is heated must be strictly controlled, because if the temperature is too high or it is heated too many times, yellowing and degradation are inevitable. According to the source and transparency requirements, the commonly available grades of recycled PC on the market are roughly as follows (the indicators are a general summary of industry standards; for specifics, refer to GB/T 40006.7 and the manufacturer's TDS):

Level NameTypical sourceKey indicatorsTypical uses
Transparent-grade recycled PCClean transparent sheets, optical filmsLight transmittance is about 89%, with a low yellow indexTransparent panels, lampshades, optical components
Natural Grade Recycled PCElectrical appliance casing, water bottleHigh gap impact, requires color matchingElectronic casing, safety helmet
Blended Modified Grade Recycled PCMixed PC CrushingPerformance adjusted according to the formula, low priceSheet material blending, non-transparent parts
Flame-retardant grade recycled PCFlame-retardant electrical enclosureFlame retardant, testing data requiredElectronic and electrical components
Titanium Dioxide Modified Recycled PCWhite appliance casingGood whiteness, surface free of black spotsWhite exterior parts
Black Recycled PCMottled shell is brokenLow price, not transparentInternal components, structural components

Market Reference: Recently, on the market, white titanium dioxide modified recycled PC with better impact resistance and whiteness is priced at around 9,000 yuan per ton; transparent grade recycled PC is more expensive due to scarce material sources and strict sorting; black or mixed grades are cheaper. When Ningbo Kolong New Materials Co., Ltd. pushes PC, they usually first ask whether it is for transparent parts or colored parts, and whether it is for outdoor or indoor use, before determining the grade— in the PC business, transparent and opaque are two completely different markets, and confusing them can lead to a large price difference.

Why is transparent-grade recycled PC so expensive? Because sources of transparent material are scarce. You can easily find a bunch of mixed-color shells, but clean, transparent, and minimally aged sheets need to be specially collected and sorted, and color sorting machines must remove any grayish or yellowed pieces. After processing into pellets, every aspect like light transmittance, haze, and yellowing index must meet the standards. Once these three thresholds are met, the price naturally goes up. Therefore, manufacturers making transparent lampshades or transparent sheets shouldn’t expect to pay the price of mixed-grade material; conversely, manufacturers making non-transparent parts don’t need to pay extra for transparency they won't use.

There’s another common pitfall for beginners with recycled PC: putting it into the machine without drying. New PC has a low moisture content, and many factories, to save trouble, just do a quick drying and start molding. Recycled PC absorbs moisture, and if it’s not fully dried, injection molding will result in silver streaks, bubbles, and a sharp drop in strength. So when using recycled PC, the drying temperature and time must be stricter than for new material, and the moisture content must be reduced to sufficiently low levels. This step doesn’t cost much in electricity, but it can save an entire batch from being scrapped. Experienced factories include the drying process in the work instructions for recycled PC, and don’t start the machine without drying.

The performance degradation isn't as severe as you think, as long as you don't let it get heated a third time.

For the accounts of recycled PCs, the key is to clearly calculate the hidden loss of 'depreciation'. To break it down:

Cost itemBrand new PC materialRecycled PCDifference Explanation
Raw material purchase priceHigh base priceMuch lowerThe price difference for the transparent grade is narrow, while the price difference for the blended grade is wide.
Transparent appearancetransparentTransparent grade, close to new materialYellowing and haze are the main risks
Mechanical propertiesStableCheck the number of sorting and heatingImpact decreases after multiple regenerations
Processing stabilityStableNeeds to be fully dryHigh moisture content is prone to hydrolysis silver streaks
Weather resistanceGoodRecycled material is prone to yellowingTest the outdoor lampshade for UV resistance first
Full-year comprehensivesuperficially expensiveNon-transparent items are more cost-effectiveHigh transparency optical components, handle with care

Boundary List — Which items can safely use recycled PC, and which should be held back for now:

Safe to use: non-transparent electronic casings, safety helmets, internal structural parts, and mixed plate materials.

Use with caution: transparent lampshades, transparent sheets, choose transparent-grade recycled PC, and measure light transmittance and yellowing index.

First verify: outdoor weather-resistant parts, test UV resistance and accelerated aging, to prevent yellowing within two years.

Do not touch: high-transparency optical lenses, optical components with extremely high requirements for haze; materials that have been regenerated three or four times for making critical load-bearing parts.

Procurement actions: Need moisture content data, need yellow index, need notch impact, and for transparent parts, also need light transmittance. None of the three can be missing.

The issue of outdoor use needs to be addressed separately. When making lampshades and sun panels from PC, they are exposed to sun and rain every day. Even new material requires added UV protection; recycled material, with its weaker yellowing resistance, will turn yellow and brittle in less than two years if used outdoors, resulting in a whole batch being scrapped. Therefore, for outdoor weather-resistant PC parts, one should either choose modified grades with UV-resistant formulations or simply use new material as a backup. The money saved on material cannot compensate for the losses of replacing the entire batch in two years — this calculation is especially important for lighting and panel manufacturers.

Determining the mixing ratio is also a technical task. When recycling PC into transparent sheets, adding too much reduces light transmittance and accelerates yellowing, while adding too little does not significantly reduce costs. The safe approach is to start with a small amount, for example, first mix in 10–20%, make sample pieces to measure light transmittance and yellowing index, and see if both the client and you can accept it, then gradually increase; each time you increase the amount, test again to map out the degradation curve. Don’t listen to others saying, 'Our factory mixed in 50%, it’s fine'; their material source, thickness, and usage environment are different from yours, so the ratio cannot be copied directly. Copying others’ ratios easily leads to accidents. Experienced sheet makers all understand that when it comes to mixing ratios, only trialing batch by batch yourself counts; most of the numbers told by others are pitfalls.

The board mixing account of Kolon New Materials: when the mixing ratio is correct, the yellowing slows down

This is a typical scenario example used to illustrate the selection idea. The order details have been adapted, so please do not take it literally. A factory in Ningbo producing PC hollow sunlight panels wanted to reduce costs and directly mixed in cheap black recycled PC, resulting in yellowing on the board surface. Two years later, the entire batch turned yellow, and customers complained at their doorstep.

After several twists and turns, they found Ningbo Kolon New Materials Co., Ltd. Kolon New Materials didn’t use all new materials, nor did they mix in entirely cheap materials. Instead, they provided a blending plan: the main material used transparent-grade recycled PC to ensure light transmission and appearance, a small portion of modified mixed material was added to reduce costs, starting with a small blend ratio, and the final ratio would be decided after measuring the light transmission and yellowing index; the drying process was adjusted accordingly to control the moisture content. Once the process ran smoothly, the appearance of the panels stabilized, the yellowing rate slowed down, and the material cost dropped by one yuan.

The principle explained in this passage is very clear: when making sheets with recycled PC, it is not a choice between 'using all new material' or 'using all recycled material,' but rather finding a mixing ratio that is acceptable in terms of translucency, yellowing, and cost. Ningbo Kolong New Materials Co., Ltd. focuses its efforts on this balance point when supplying PC—neither blindly saving money nor blindly seeking new material.

When all is said and done, expensive doesn't necessarily mean costly: the small amount of money saved with cheaper materials may not withstand yellowing and returns two years later, which is the real cost.

When choosing recycled PC, first determine whether you want it to be transparent or blended.

Common applications condensed into a quick reference table:

Application scenarioRecommendation LevelPrecautionsWhen to stop using
Transparent polycarbonate sheet, lampshadeTransparent-grade recycled PCMeasurement of light transmittance and yellowness indexOutdoor high weather-resistant parts should first be tested for UV resistance
Electronic and electrical enclosuresNatural/Modified Recycled PCColor matching, batch lockingHighlight trim carefully
Safety helmets, protective gearNatural Grade Recycled PCGap Impact TestVerify the load-bearing safety component first
Non-transparent structural memberBlended/Black Recycled PCfixed dosage ratioDo not use black material for transparent parts
Flame-retardant electrical componentsFlame-retardant grade recycled PCFlame retardant dataDo not promise flame retardancy without data

Three concluding sentences: First, determine whether your item needs to be transparent or opaque, then ask whether it's for outdoor or indoor use, and only then talk about the price. Once these two questions are answered clearly, the accounting for PC won't go wrong—you save where you should save, stay steady where you should stay steady, without compromising either the client or the profit.

A reminder when purchasing recycled PC: don't just look at whether the pellets are transparent; you need to see if they're dry after drying and stable after testing. Grab a handful of pellets—if they appear dark, gray, or have mixed colors, it's likely been recycled multiple times or poorly sorted. Check the test report: only if the moisture content, yellowing index, and notched impact values are all within range is the material worth trying. Start with a small batch on the machine, ensure the drying and process are running properly, and then talk about yearly usage—this recycled PC business can't be rushed.

How much can recycled PC really save? It largely depends on what material you originally used and what part you are making. For non-transparent structural parts, substituting premium new material with mixed grades can cut the per-ton material cost significantly; for transparent sheets, using transparent-grade mixtures mainly saves on the premium of new material, while performance loss has to be managed through the mixing ratio. The calculation isn’t a single number—it depends on how much you compromise on transparency, weather resistance, and impact resistance for that part. The more you can compromise, the more you save; if you refuse to compromise, then don’t force savings.

The performance degradation of recycled PCs isn't that scary; what's scary is that no one told you how many times it has been baked.

Selection of recycled PC: Transparent grade and mixed grade each follow their own path

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

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