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Good Vibrations: Ultrasonic Technology Applied to Micro Molding

By: Tony Deligio 25. June 2014

Back in 2007, researchers at the Ascamm Technology Centre in Barcelona, Spain started investigating melting thermoplastics via ultrasonic energy. After proving out the process, the researchers considered possible commercial applications, according to Enric Sirera, who became sales director at Ultrasion, the commercial venture spun off in 2010 from Ascamm’s to commercialize the invention. 

 

“[The researchers] saw a market need for small parts, micro parts, including ones with higher aspect ratios,” Sirera explained. “They saw a commercial opportunity.” Ultrasion was created in 2010 as means of “designing, developing, and industrializing a machine surrounding this ultrasonic molding process.”

 

Ultrasion’s vision is to use ultrasonic waves to melt plastics prior to molding, as opposed to the shear and radiant heating used in the heater-band, reciprocating-screw, and barrel set up of traditional injection molding. By doing so, the researchers believed they could prepare only the required amount of material for each part versus bringing an entire barrel of material up to temperature, with the subsequent residence time and potential for degradation.

 

In their first crack at a ultrasonic-centered machine, the researchers constructed a prototype press by taking a standard injection molding machine, removing the entire injection unit and substituting one of their design.

 

“It worked perfectly,” Sirera recalled, “it was great step forward. At that point, however, we realized that the hydraulics and the clamping force were over sized and over dimension for what we needed. So, we said, ‘Hey, let’s think about redesigning a new machine according to this process.’”

 

With the first prototype machine completed in 2010, the company hit the show circuit to begin promoting the technology, including stops in Germany at Fakuma and Orlando at NPE2012. Last year, Ultrasion participated in the K Show in Germany, as commercial sales began in earnest.

 

Today, Sirera notes there are 12 machines in the field, with seven running production and the rest involved in further research at universities and R&D centers. Those machines are spread throughout the U.S., U.K., Poland, the Netherlands, and Spain, working in medical, aerospace, and precision mechanics applications.

 

Key difference
Sirera notes that one key differentiator for Ultrasion’s molding technology (they drop the injection, more on that later), is how ultrasonic melting of the pellets lowers the material’s viscosity.

 

“This means at the same melting temperatures,” Sirera says, “the viscosity by ultrasonic heating drops down, leading to the possibility of molding at much lower pressure, with less stresses internally, as well as the ability to make the material flow into thinner, tinier geometries that previously had not been able to be filled.”

 

Instead of a traditional hopper-fed barrel and screw, Ultrasion machines feature a dosing unit, dispensing only the amount of material needed to be melted for each cycle. Once inside the dosing chamber, the resin is heated via ultrasonic waves, vibrating the plastic and creating spaces within its molecular structure. “When you create more space around the molecules,” Sirera explains, “you lower the viscosity. As the free volume increases, the viscosity drops down.”

 

In micro injection molding, Sirera notes that pressures can easily rise to 1200 bar and higher. With ultrasonic melting, however, those pressures drop down to the 300 to 500 bar range.

 

The Ultrasion machine is technically rated with a clamping force of 3 m.t., but even that description is overkill, according to Sirera. In production, he notes that  the Ultrasion machine typically uses from 1.5 to 2.2 m.t. of clamping force. As an added bonus, the elimination of heater bands, as well as hydraulic pumps and motors normally used to keep the clamp shut under high pressure, means that energy consumption for the Ultrasion is reduced by 85 to 90 percent compared to a standard injection molding machine.

 

Residence time
In a standard micromolding setup up, where a part might utilize a .1g shot and the machine has a 100g capacity barrel, a molder would have to go through 1000 shots to clear the barrel. “This can lead to big problems,” Sirera notes. In the Ultrasion design, the dosing unit handles the material at room temperature, and only as needed.

 

“Imagine a hopper with material at room temperature,” Sirera explains. “The machine stays at room temperature. As soon as we want to mold a part, we close the mold, dose raw material as pellets into the mold—using just the amount of material for that shot—and then the horn comes down, vibrates, and melts only the amount of material dosed into that shot.” Once melted, a plunger pushes the molten plastic into the tool cavity at much lower pressures.

 

“There’s no residence time at all, which means the machine can be started and stopped at any time,” Sirera says, adding that there are no purging operations either. If a material change is needed, the hopper is simply emptied and refilled.

 

Sirera says parts still have a runner and sprue, which can become outsized in micro molding, but here he notes Ultrasion still saves between 40 to 70 percent of the equivalent cold runner compared to traditional micro injection molding.

For the material, eliminating the dual stresses of thermal degradation caused by long residence times as well as injection under high pressure has had some interesting results.

 

Ultrasion has seen less change in the polymer’s molecular weight, helping materials retain mechanical properties, while the process also means the polymer chains “refreeze nicely”, according to Sirera, resulting in a stronger, more homogenous melt and part.

 

Apart from silicones, Sirera notes that the technology is suitable for all types of thermoplastics, including high-temperature materials like PEEK, PSU, LCP, and POM. In filled materials, or ones with additives, Ultrasion has also seen better dispersion and more homogeneity in the finished compounds and parts. At this time, maximum overall shot sizes are around 1.5 to 2 g, but could go bigger, to a point.

 

“If you ask me if some day will we make a bumper fascia using ultrasonic molding, I don’t think so,” Sirera says, before adding. “It’s too soon to tell.”

 

That doesn’t mean there aren’t big opportunities in small parts, however. “Mold geometries that had previously proven impossible are now possible,” Sirera says. “When we talk about design for manufacturing, now you have a new manufacturing technique that will allow you to try new geometries. We don’t know what the limits are yet, but we envision a huge opportunity.”

Biocompatible, Zinc-Based Antibacterial Treatment For Plastics

By: Lilli Manolis Sherman 19. June 2014

A unique patented antimicrobial treatment has been developed by Parx Plastics, a two-year-old business founded by Michele Fiori and Michael van der Jagt to explore the possibilities of creating antibacterial plastics. Headquartered in The Netherlands, with laboratory and production facilities in Italy, Parx Plastics was named by the European Commission as one of top three tech startups in Europe in the prestigious Tech AllStars competition 2014.

 

By applying biomimetics and nanotechnology, a method was developed to make an intrinsic change to any plastic that results in a mechanical/physical property that acts against bacteria or microorganisms, according to van der Jagt. The technology does not use chemicals, biocides, heavy metals or nanoparticles. Instead, it makes use of the one of the body’s most abundant trace elements: zinc. Moreover, it is said to kill 99% of the bacteria and microorganisms that are on the surface of a product within 24 hours, in step with ISO 22196 testing guidelines.  Says van der Jagt, “The technology can be used nearly for any end-use product, but its unique characteristics—biocompatible, non-toxic, non-migratory, makes it especially suitable for food packaging to prolong shelf life and medical devices where it reduces the chances of infection with implants.”

 

To date, the treatment has been applied to BPA-free copolyester Tritan EX401 from Eastman Chemical where its successful incorporation of the antibacterial property resulted in 98.7% for Gram- and 98% for Gram+ bacteria. The material is targeted at infant care products and the Parx technology opens up broader opportunities. “So, if you need to make an antibacterial product that is normally made out of Eastman’s Tritan, we will treat 3% of the Tritan granulate/pellets of the Tritan you require. That 3%-treated plastic is referred to as Saniconcentrate, which is mixed in with the untreated 97% portion prior to production. We are now in direct contact with the molder of one of these products,”says van der Jagt.  He also notes that the company has had equally successful results in applying its treatment to BASF’s Terluran GP-35 ABS copolymer, a standard ABS grade with a low viscosity used in a very wide range of applications.

 

 

Shrimp Shells Play Key Role In New Bioplastic

By: Lilli Manolis Sherman 19. June 2014

Researchers from Harvard University’s Wyss Institute have developed a fully-degradable bioplastic isolated from shrimp shells which they report can be molded into products such as cell phones, food containers and toys which boast many of the key properties as those made by their traditional plastic counterparts.

 

Director of platform development Bob Cunningham sees potential application for the new bioplastic for large-scale manufacturing of consumer products. The group is actively in the process of seeking potential partners, ranging from raw material suppliers and compounders to molders and end-users. Initially, the ideal partner would appear to be a compounder or resin supplier with bioplastics experience.

 

The new bioplastic is partly made of chitosan, a form of chitin, said to be Earth’s second most abundant organic material. A tough polysaccharide, chitin is responsible for the hardy shells of shrimp and other crustaceans, armor-like insect cuticles, and flexible butterfly wings. Led by postdoctoral fellow Javier Fernandez, and founding director Don Ingber, the Wyss team developed a new way to process the material so that it can be fabricated into large 3D objects and complex shapes using traditional casting or injection molding techniques. In addition, the chitosan bioplastic breaks down when returned to the environment within about two weeks, and it releases rich nutrients that support plant growth.

 

Depending on the chitosan fabrication method used, you either get a chitosan material that is brittle and opaque—thus, unusable, or tough and transparent, according to Fernandez. After fully characterizing in detail how factors like temperature and concentration affect the mechanical properties of chitosan on a molecular level, the two researchers honed-in on a method that produced a pliable liquid crystal material that was just right for use in large-scale injection molding or casting manufacturing.

 

Also significant is that they came up with a way to combat the problem of shrinkage whereby the chitosan polymer fails to maintain its original shape after injection molding. Adding wood flour did the trick! “You can make virtually mold any 3D form with impressive precision from this type of chitosan”, says Fernandez, who first molded a series of chess pieces as a demonstration. This bioplastic can also be modified for use in water and also can be easily dyed by changing the acidity of the chitosan solution. And the dyes can be collected again and reused when the material is recycled. 

 

 

Want to find or compare materials data for different resins, grades, or suppliers? Check out Plastic Technology’s “Plaspec Global materials database”.

Ferro To Exit Specialty Plastics And Polymer Additives Businesses

By: Lilli Manolis Sherman 18. June 2014

It was just a year ago that A.Schulman made an unsuccessful bid to acquire all of Ferro Corp., but the acquisition of the latter’s specialty plastics business by A. Schulman will be a done deal by early third quarter. Moreover, Ferro has hired KeyBanc Capital Markets to help find a buyer for its polymer additives business.

 

Ferro chairman, president and CEO Peter Thomas says, the company will aim to strengthen its performance materials product lines which include performance coatings, performance colors and glass, and pigments, powders and oxides. The latter group includes complex inorganic color pigments for plastics. “Our strategic vision is to become the premier global functional coatings and color solutions company, building on our core competencies in glass and color technologies.”

 

What A. Schulman is gaining is an expanded product portfolio, technical solutions, and global resources. Included are custom engineered compounds, colorants and liquid coatings that are used in such markets as packaging, construction, and transportation. They are made in four U.S. plants and one in Spain. Not included in the sale are Ferro’s liquid colorants and dispersions business in Edison, N.J., and its specialty plastics operations in Venezuala. This acquisition will be the tenth made by A. Schulman within the last four years, along with three joint ventures formed. The company is aiming to strengthen its U.S. operations and expand its global reach in engineered plastics, masterbatches and custom performance colorants.

 

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Want to find or compare materials data for different resins, grades, or suppliers? Check out Plastic Technology’s “Plaspec Global materials database”.

From pipeline to pellet: Shale gas pushes petrochemical projects forward

By: Tony Deligio 18. June 2014

On June 13, the first barrels of ethane extracted during oil production at North Dakota’s Bakken Shale play were utilized by NOVA Chemicals at its Joffre, Alberta complex.

 

On June 17, Chevron Phillips Chemical hosted a groundbreaking for the polyethylene units at its U.S. Gulf Coast (USGC) Petrochemicals Project with polyethylene production slated for Baytown and Old Ocean, Texas.

 

NOVA is utilizing ethane derived from natural gas at Hess Corp.’s Tioga, North Dakota plant, which is transported into Alberta via the Vantage Pipeline. That pipeline has an initial design capacity of 40,000 barrels/day but is expandable to greater than 60,000 barrels/day.

 

“Ethane extracted from associated gas produced from Bakken Shale is expected to be a growing and stable feedstock supply source for the Alberta petrochemical industry.”

 

NOVA has already utilized natural gas from additional alternative outlets. In the first quarter, it applied ethane extracted from off-gas produced at Alberta oil sands, while Marcellus Shale basin based ethane became “a regular feedstock” at its Corunna, Ontario cracker, the company noted in first quarter earnings released on May 1.

 

In that statement, the company said it expects Joffre to be at nameplate capacity, north of 1 billion pounds, with plans to transition up to 100% natural gas liquids later this summer. At that time, the company reported a more than 30% increase in profits compared to the first quarter of 2013, citing increased operating profits and higher margins, specifically in its polyethylene segment.

 

"The introduction of Bakken Shale-based ethane into the feedstock diet at Joffre marks an important milestone in the diversification of our ethane sources for the region and our NOVA 2020 strategy to capitalize on North American demand,” stated Todd Karran, NOVA Chemicals Acting CEO and CFO.

 

On June 12, Chevron Phillips Chemical announced the successful commissioning and start-up of what it calls “the world’s largest” on-purpose 1-hexene plant. That unit has capacity for 250,000 m.t. (551 million lb).

 

Here too, the influence of shale was cited as real-live production begins:

 

"Our investment to expand 1-hexene production is due in part to Texas’ growth as a major international hub for the petrochemical industry and the increased supply of competitive feedstocks in the U.S. from the development of shale resources,” said Pete Cella, CEO of Chevron Phillips Chemical.

With shale-gas-sourced pellets entering, or soon to enter the market, the next question becomes: Will North American processors see a pricing benefit from feedstock-advantaged polyolefins, or will the cost benefts only go to producers bottom lines?

 

Chevron Phillips Chemical's projects by the numbers:

  • Location: Cedar Bayou Chemical Complex in Baytown, Texas
  • Annual Capacity: 250,000 m.t. (551,000,000 lb)
  • Technology: third* plant to utilize Chevron Phillips Chemical’s proprietary selective on-purpose 1-hexene technology, which produces comonomer grade 1-hexene from ethylene.

*Qatar Chemical Company Ltd.’s (Q-Chem) facility in Mesaieed, Qatar, and Saudi Polymers Company plant in Al Jubail, Saudi Arabia are the other two.

 

Chevron Phillips, U.S. Gulf Coast (USGC) Petrochemicals Project

  • Where: Cedar Bayou plant, Baytown, Texas, and Old Ocean, Texas
  • What:  1.5 million m.t./year (3.3 billion lb/year) ethane cracker in Baytown, and two 500,000 m.t./year (1.1 billion lb/year) capacity polyethylene facilities in Old Ocean, Texas

 

Ed. Note: But wait, there's more!

 

This morning ExxonMobil Chemical announced the launch of its multi-billion dollar expansion of its Baytown, Texas operation. Per the company:

 

The steam cracker will have a capacity of up to 1.5 million tons per year and provide ethylene feedstock for downstream chemical processing, including processing at two new 650,000 tons per year high performance polyethylene lines at the company's Mont Belvieu plastics plant.




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