New additives can improve the scratch/scratch resistance of molded and extruded parts. #Processing skills

Processors and their customers in the automotive, electronics, and consumer product sectors are looking for a way to protect plastics from scratches and damage during storage, transportation, and use without the need for high paint or hard coating costs. A new additive may be the answer.

The organoclay with special surface treatment can maintain the surface gloss of nylon and acrylic without affecting UV resistance or chemical resistance, toughness or modulus. It also showed promising results in polycarbonate, PET and PVC/acrylic.

There are many types of tests, but Solid-TT shows good performance in pencil hardness, Erickson scratch and Crockmaster scratch tests.

According to the Erichsen scratch test, the scratch resistance of nylon 6 with Solid-TT is increased by 71%, while the scratch resistance of transparent alicyclic nylon 12 is increased by 55%.

When Solid-TT is added to extrusion-grade nylon 6, the mechanical properties are significantly better than the same compound of the same nylon.

After adding Solid-TT, PVC/PMMA alloy shows a very promising improvement in scratch resistance.

The Solid-TT additive has almost no effect on the molding and extrusion of nylon or acrylic compounds.

The following is the test data of a new additive, which can improve the surface durability of engineering thermoplastics under extremely low loading, and even improve the mechanical properties. 

You want the shiny interior of your new car to look like new for as long as possible. After all, you paid a considerable price for it. Therefore, you try to avoid knocking and gouging in daily use. Therefore, after six months, your disappointment cannot be concealed when the internal panel, console and gear lever cover are worn and worn.

Designers of these nylon or polycarbonate products cannot rely on hard coats or painted exposed surfaces to avoid such damage. This is too difficult and too expensive. Automotive OEMs are not the only companies concerned with scratch and wear performance. Many thermoplastic molders and extruders in consumer products, electronics, and interior decoration also need better-performing resins to prevent abuse and maintain their surface quality for as long as possible. Molders of such products are frustrated by the high rate of wear that occurs on nylon parts at some time between the injection molding machine and the end user. Some people have turned to a new, cost-effective method.

TenasiTech (U.S. office in Marblehead, Massachusetts) has developed a new additive called Solid-TT, which can be significant when blended into resin (usually only 1% of the weight of the host polymer) Improve scratch resistance and scratch resistance without painting or hard coating. Molded parts and extruded plates made with this additive can withstand rougher treatments without damaging the surface (see launch in January 2016). The following are more technical details and test data about this new technology.

The development of this additive for surface treatment clay began in the research laboratory of the University of Queensland in Australia. This research produced a patented organoclay with a new type of surface treatment. When mixed with thermoplastics, the unique organic treatment helps to maximize the decomposition of clay.

This additive cannot replace the hard coat. Companies that have experienced the cost and time required to build a hard coating production line are unlikely to change. However, the vast majority of plastic products in any particular resin market will never benefit from high-performance coatings or paints. Not only is hard coating too expensive for many end-uses, but it is also well known that it is difficult to effectively hard coat molded parts with curved surfaces. In addition, extruded sheets are usually thermoformed, which involves stretched sheets. This may mean that hard coating is not an option, as it may damage the coating. 

Solid-TT is a real polymer enhancer, not just a lubricant or other migration additives. Therefore, there are no problems with surface rub-off or long-term durability. Products made with new additives can withstand daily cleaning and maintain a smooth surface.

Standard twin screw extrusion is used to mix the additives into the resin. The resin can then be molded or extruded normally. The molder says that the cycle time will not increase, and only a slight increase in injection pressure is required. 

The Solid-TT additive shows significantly improved scratch or abrasion protection in a range of nylon and acrylic resins of different viscosities. The additive will not degrade the polymer or cause significant discoloration. It is important that the addition of additives to thermoplastics does not impair impact resistance and drop resistance. This is the main disadvantage of previous attempts to make surface hardness performance additives. The additive also does not affect the modulus of nylon 6.

When Solid-TT is added to extrusion grade nylon 6, its mechanical properties are significantly better than the mechanical properties of the same nylon without it. For example, Nycoa 1637 nylon 6 has a 41% increase in strain at break, which contains 1% Solid-TT, compared to nylon composite without it. A 34% increase in toughness and a 14% increase in tensile strength were also recorded (see Figure 2). 

Thermoplastics containing Solid-TT have undergone 1000 hours of accelerated UV aging. Compared with pure resin, plastic does not show any additional degradation. 

In addition, the additive still maintains excellent pencil hardness performance after UV irradiation. Considering the low addition rate of this performance additive, the chemical resistance of the plastic is not affected, which is logical.

Scratch and scratch test performance Scratch and scratch behavior can be very complex, and there is no universally accepted single test to measure performance. In a wide range of tests, pencil hardness is a simple shorthand method to communicate between different polymers and be understood on a global scale. 

Other tests, such as Erichsen Scratch (ISO 4586-2) and Taber Linear Scratch (ISO 1518:2001), are commonly used for scratch testing. For scratch resistance, rubbing and wiping tests are usually used, such as Crockmaster.

According to each scratch test, no method to prevent scratches and abrasions is qualified. This is true even for some hard coating methods. Solid-TT additives cannot prevent more aggressive gouging-type scratches. Tests such as Taber Abrasion can be very challenging, and it can be very difficult to distinguish polymers containing Solid-TT. 

It is very common for the eventual scratches or scrapes to qualify to occur at the scene. The processor or its OEM customer may conduct their standard laboratory testing and the time required for the product to survive without excessive surface damage in normal use. Sometimes, on-site testing is as simple as misusing car keys or nails. In other cases, customers place their final products (such as skis or bottles) in the typical "lifetime" of their final market.

In the test, according to the turntable Erichsen scratch test (see Figure 1), the scratch resistance of nylon 6 containing Solid-TT was improved by 71%, while the scratch resistance of transparent alicyclic nylon 12 containing additives was improved. Up 55%. Scratch resistance is different from scratch resistance. It is a surface change caused by friction or friction, such as color, gloss or haze, but there is no significant material loss on the surface. 

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The friction test is a good way to measure this: In the so-called Crockmaster test, a robotic finger uses a consistent force to drag a standardized textile onto a plastic surface for a predetermined number of cycles. In order to simulate the normal use of car interiors, this test may require up to 40,000 cloth wiping cycles. For mobile consumer devices, the number of cycles of using textiles to match clothes can be 5000 to 10,000. In either case, a visual evaluation of plastics with and without additives is carried out. 

When performing these tests on nylon and acrylic resins, Solid-TT has been shown to significantly reduce damage. For polycarbonate and other polymers, similar results are expected. 

The scratch performance of BEYOND NYLON polycarbonate using Solid-TT shows that the pencil hardness is "H", while the pencil hardness is "2B" without additives. This opens up huge potential for PC molded products and sheets, because hard coating is still an option that is too expensive.

In the external test, PMMA formulated with Solid-TT showed damage at "7H" pencil hardness, but "4H" without additives. More importantly, PET and PVC/PMMA alloys show very promising improvements in scratch resistance using additives, although this work is still under development.

PVC/PMMA alloy is an excellent choice for aircraft interior panels, such as bulkhead partitions. They are very tough and chemically resistant. However, like many polymers, they can be damaged by scratches. The hard coating of PVC/PMMA sheet is not an economical choice, nor is it inappropriate, because the sheet will be thermoformed into the final product shape.

TenasiTech measured the scratch resistance of PVC/PMMA alloy plates and found that according to the Erichsen scratch test (Figure 3), the force required to leave a permanent scratch has doubled. 

About the author: Richard Marshall is the CEO of TenasiTech Pty Ltd. headquartered in Australia. He has 22 years of experience in technology startups, venture funds and top multinational companies. He is the co-author of the chapter on commercialization of nanomaterials for industrial applications published in 2013. He holds an MBA degree from Oxford University and an undergraduate degree in engineering and science from Queensland University of Technology. Contact: (518) 572-8572; richard@tenasitech.com, tenasitech.com. 

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