additives for recycling: maintaining value the second time around. - polycarbonate compact sheet
What needs depends entirely on the type of resin, where it comes from and what you want it to do in your next life.
In circular trade, the cruel economic pressure has never eased, and it is easy to think that additives are unnecessary compound costs.
Therefore, even those ingredients that are considered essential in the original resin formula may look like expensive decorations when passing the ball-making line for the second time.
However, today's recycling market needs reprocessing resin that meets the same quality standards as Virgin's peers.
Additives may be the best way to keep the old resin working and looking like a new one.
Some compounds have increased recovery to new levels of value by relying on stabilizer, lubricant, impact modifier and other processing and Performance Additives-
Sometimes even higher than the original material.
At the same time, additives can help offset the lack of uniformity of the recovery stream, bringing a single batch to a consistent quality standard.
For example, MRC polymers adopt both strategies.
The company works from industrial waste and post-treatment resin
Consumer sources, producing compounds that compete with Virgin in the most demanding automotive electronics applications, product development manager George Staniulis said: "additives are absolutely critical to our business.
"We can't live without them.
He explained that directly recycled polymers do not have the physical properties or consistency required for these high-end products at alluses.
Similarly, at the quantum chemical Resource Recovery Facility in Heath, Ohio, additives help to maintain the quality of high density polyethylene recycling.
"Using antioxidants is a way for us to differentiate ourselves from our competitors," said acting manager Bruce Pearson . ".
Additives will become more important as the resin begins to be used more than once.
"As the recycled resin itself is recycled, additives may have a greater impact on more recyclers," predicted Gerry Fisbbeck. p.
Recycling giant weelman
Johnson Ville, S. C.
Next to the mechanism of recycling technology-
Sorting, cleaning, grinding and re-engineering balls--
Additives for post-treatment are still a relatively untapped frontier.
"So far, most of the attention has been focused on solving all these mechanical engineering problems," said Peter Solera, a senior scientist at the Ciba additive . ".
Fishbeck of Wellman added, "First of all, make sure the recycles are contaminants --
You are free and free most of the time.
Then, additives can help you go further.
"Over the past year, an increasing number of additive suppliers have recognized the unique chemical requirements of reprocessing materials.
The various antioxidants, light stabilizer, impact modifiers and other chemicals used in recycling may be substantially the same as those used by Virgin, but there are also mixtures specifically used for recycling applications.
From recent applications, more information has surfaced about the real benefits of additive recycling.
When polymer degradation poses a critical threat to physical performance maintenance, re-stabilization is the primary solution.
"By re-stabilizing, you can protect the property and go back to the heights
Value application, "said Joseph Puglisi, product director, additive polymer, Ciba.
Depending on the cause of polymer degradation and the intended end-use, many recycled thermoplastic plastics can benefit from antioxidants, light stabilizer, or both.
The universal antioxidant strategy for the recovery of many resins requires blocked phenol and phosphate mixtures--
Or less, there is only one component.
Suzanne Dietz, chief chemist for GE specialty chemicals, noted that due to the same degradation mechanisms suffered by Virgin and regrind, they all benefit from the same stable products.
However, the required load may move up during the recycling process.
For example, antioxidants usually used at 220 ppm will usually be at 1000-
Dietz says 5000 ppm is needed to stabilize recycling.
Dietz pointed out that due to factors such as the level and purity of residual additives in raw materials, the optimal load amount and proportion of binary components vary greatly.
Different resins also have different stability requirements.
For example, cross-linking or polymer breaking may occur in the post-treatment process of high-density polyethylene, both of which change the molecular-
According to Dietz, this degradation is manifested in the transformation of melting
Stream index, which may lead to a drop in processing problems and physical properties of subsequent users.
As a way to avoid changes in high density polyethylene meltflow, antioxidant mixtures can help regardless of their direction.
The multiple extrusion processes in the Ge Laboratory show that the melt flow of high density polyethylene is more consistent with the stability.
Flow consistency, the mixture of Ultranox 626 phosphate and Ultranox 276 blocked phenol played a role in the post-treatment of 100%consumer HDPE (see Fig. 1).
Dietz also pointed out that the phosphate inhibited the development of color and only produced-0. 46 versus +9.
04 for the recovery of unstable HDPE.
Ciba's work in the newly established plastic recycling additive group in Switzerland has shown that there are similar improvements in the recovered high density polyethylene melt
Flow consistency through the actions of the company's Irganox phenol and Irgafos phosphate.
In polypropylene, degradation produces polymer broken chains, and the team has demonstrated that the phosphate/phenol mixture can enhance MFI by multiple extrusion.
In one experiment, the stable PP sample maintained the same MFI after five extruder passes, as an unstable reference sample retained after only two passes (see Fig. 2).
At the same time, the thermal stability provided by the stability is far beyond the thermal stability of the substrate (Fig. 3).
For low density polyethylene and high density polyethylene, USI Div of quantum chemistry.
BHT antioxidants have been included in the spectrum technology series of additive concentrates specially formulated for recycling.
Although the individual requirements of PET are different from olefin, it can be obtained from the increased stability.
Dietz said that PET stability should rely on higher levels of phosphate to prevent molecules-weight, or I. V.
, Lose and maintain acceptable colors (Fig. 4).
In addition, PET recycling may be particularly applicable-dependent.
Wellman's Fishbeck pointed out that only "traditional" additives are needed for fiber-recycled PET ---
Such as bright agent and titanium dioxide used for anti-light agent.
But for the new value
PET recycling applications, such as thermoforming plates, are added to the requirements for additives.
"There is no doubt that more additives are needed for thermoforming," Fishbeck said . ".
"Different grades of performance are required, which correspond to different additive requirements.
"The benefits of stability are also applicable to engineering resins;
Here, the consistency of flow is of special importance.
"We have seen a decrease in viscosity corresponding to a decrease in mechanical properties.
Antioxidants inhibit this molecule
Staniulis of MRC said: "The weight is down and he cites experience with polycarbonate, TP polyester, nylon and nylon alloys.
In addition, for most customers of MRC, consistent flow is a non-
Prerequisites for doing business.
"The change in viscosity and shear rate of our resin cannot exceed 10%," Staniulis notes . ".
Some customers even asked for three-
Sigma quality grade-
MRC said it reached a goal.
The research work of Ciba also proves the potential of additives in saving the physical properties of engineering resin (Fig. 5).
In contrast, according to the supplier, there does not appear to be a special demand for stability or additives in PVC post-processing.
"Most compounds contain enough additives to carry out two or three cycles," said Peggy holthorpe, head of technical services at Elf.
If not, according to don Brilliant, technical director of Witco Polymer Additives, all recovered compounds need to be injected with the same kind of additives used in the first run.
Let light and heat--
Whether from processing or final use--
Not the only enemy of recycled plastic.
Applications that expose the resin to sunlight or other UV sources, such as outdoor furniture, also threaten the life of the resin.
Today's typical UV stabilization system will be blocked in combination-
Amine light stabilizer (HALS)
According to the Puglisi of Ciba, the color is protected with an ultraviolet absorption device.
A Ciba weather resistance study found that 1000 ppm was added (0. 1%)
Of the company's Tinuvin 770 HALS, 5-year-
The old milk crate achieves the same weather resistance as the original high density polyethylene.
In the absence of re-stabilization, 100% of recycled high density polyethylene had crack formation in less than 2000 hours;
Stable samples withstand cracks for more than 8000 hoursfree.
The tensile impact strength of the unstable recovery is also well below the marking set by the re-stabilized high density polyethylene.
Responding to the need for different types of degradation ---thermal and uv--
At the same time, some new additive systems combine antioxidants and recycle them against the stabilizer in an optimized proportion.
Ciba recently introduced two of these blends under the trademark of Recyclostab.
According to Puglisi, these products are already sold in Europe and should be available domestically in the third quarter.
Both substances are composed of blocked phenol and phosphate, one containing a light stabilizer.
The Recyclostab 400 series is suitable for the length of the application
Thermal protection terms, especially plastics from mixed waste streams.
The Recyclostab 800 series is also suitable for applications that require light stability.
Based on 15 years of recycling experience, MA polymers also sell additive packaging optimized for post-processing applications.
The company can develop its multi-component antioxidant and photostable packaging for injection molding, blow molding, sheet extrusion and thermoforming applications of various resins.
In addition to using additives to recover or maintain physical properties at the original level, some compounds use the following values
The strategy of upgrading recycled resin has been added to enable them to achieve better physical properties than before.
Michel Bitritto, resource recovery and recycling manager at Hoechst Celanese, said: "We have not used any additives other than those that have the ability to improve performance . ".
She pointed to the glass.
Fiber reinforcement and impact modifiers are two of the most obvious choices to achieve these goals.
AmeriHaas, a supplier, reports that its Paraloid EXL impact modifier has received new recycling applications ---
As for the polycarbonate compact
Make the disc scrap into resin suitable for the manufacture of a "jewelry box" or a disc holder.
These PC disc holders, previously made from black hip trays and clear ABS covers, have now replaced the early resin of a customer's factory. At 5-
At a load level of 7%, the impact modifier more than doubled the strength of the PC, while allowing the PC to accommodate aluminum metal layers in scrap discs.
Staniulis said that the MRC polymer also uses CDs as part of its raw material, and it uses Impact Modifiers extensively.
In two automotive applications-
Wheel cover and internal console components--
The intensity of Impact between Impact retention and loss of business has increased.
GE specialty chemicals recommend its Blendex ABS modified resin to improve the impact strength and color retention of the mixture of recycled ABS, SAN, PVC and these resins.
The MRC wheel cover, produced by nylon/PPE alloy, is more compatible and points to another route for upgrading recycled resin ---
Combine different materials together for the necessary performance.
MRC also sells recycling-
The PC/PET based mixture is called Stanuloy.
For the mixture, the key to success or failure may be the use of the capacity additive.
"The whole area of capacity enhancement technology is the fertile soil for recycling," Staniulis noted . ".
Although the technology is still highly proprietary, a number of different chemicals and polymers have shown their effectiveness as photo-compatible agents (see PT, Feb. '89, p. 67).
One of the new products is amerihaas' Paraloid EXL-
Acrylic 4100 series-
Acetone polymer for adding capacity nylon/ABS and PC/nylon systems.
Assistant lawyer of the company PM-
800 is an acrylic-olefin graft that can be applied to polyethylenebased blends.
"We have seen the success of PM --
"PC/PE mixed products make up 800," said Greg Torchiana, national sales representative . ".
In addition to engineering mixing, the volumetric agent can also help improve the normal low physical performance of the mixed waste logistics.
In New Orleans this year, A paper was published by. A. Adewole and M. D.
Wolkowicz, Himont, USA shows the beneficial effect of Shell's Kraton fgyp1x Malay MEBS polymer on the physical properties of PP industrial waste and post-treatment mixturesconsumer HDPE.
By changing the level of Kraton between 1% and 7%, the authors achieved a different balance of impact and tensile properties. BASF Corp .
Has provided you with three types of mixed developed photo-compatible agentsPlastic recycling.
These RCM polymer mixture products are designed to enhance the performance of PS/PE, PS/PP and ABS/PP blends (see PT, Feb. '93, p. 14).
In order to make it easier for the mixture or mixed material to be composite, the processing aids can work. Struktol Co.
It is reported that a recycled customer is using its TR 044 fat
The ester process helps to produce improved nylon/PET dispersion from re-grinding through viscosity adjustment.
The company also provides processing aids, such as TR 016, consisting of fatty acid metal salts and amide.
Don Hall, product manager, explained that because these have hydrogen sites that can be used for bonding, they can be used as both a flow auxiliary agent and a connecting agent when mixing recycled resin.
Quantum notes that Spectratech PM 11607 concentrate containing fluorine polymer processing aids helps to increase production and prevent melting breaks in recycled olefin.
Even recyclers who don't use other additives look good, they say they use pigments often to overcome appearance barriers.
Color helps cover up cosmetic effects that are contaminated, slightly degraded, or mixed waste mottled appearance.
"Even if it is stable, the color will change, so you can use the color correction device," said Staniulis of MRC . " He used blue tones to offset the yellow color.
For example, Quantum provides color concentrates specifically for recycling as part of the Spectratech series.
According to Ken Auer, the market manager, a series of dark brown black resins can color the mixed resin evenly around about 2. 5% loadings.
The company also offers recyclers a variety of custom colors to improve the quality of the appearance that black or brown will not appear.
Foaming resin from mixed flow may be another way to improve the appearance and physical properties.
In addition to the potential favorable density reduction, foaming can also eliminate warping, increase impact strength, and provide a more attractive surface, Auer explained.
Final applications like plastic wood can gain the aesthetic and functional value they would otherwise lack.
Auer added that some quantum recycling customers are using concentrates of azo frother. NO CURE-
All additives can not only solve the problem of recyclers, but also produce some additives.
The cost is the biggest.
For example, a recycler sees the era of carbon black used to shield the mix
The cost of color spots is as high as the recycled resin raw material itself. Non-
Although the additive has a leveling effect, the uniformity of the recovery flow is still another key obstacle.
"One of the dilemmas we see is the issue of additive control," explains Wellman's Fishbeck . ".
"Recycling consistency is variable in the first place, so if it's hard to predict what additive levels are needed.
Bitritto of Hoechst warns that additives-
Induced compatibility issues can plague a mixture of diverse, stable and modified recycling-
Even in a single signal from singstream.
In this case, the best additive solution for Hoechst so far is "adding more virgins," she said ".