Canadian Plastics

Additives Reports: Mission Impossible? Not anymore

CLARIFYING AGENTA nucleating/clarifying agent for polypropylene based on new chemistry has been introduced by Crompton Corporation. Moldpro 931 is melt-blendable, but sells for less than melt-blendab...

January 1, 2003   By Cindy Macdonald, associate editor



CLARIFYING AGENT

A nucleating/clarifying agent for polypropylene based on new chemistry has been introduced by Crompton Corporation. Moldpro 931 is melt-blendable, but sells for less than melt-blendable sorbitol-type (DBS) clarifiers or non-melt-blendable organophospate salts, according to Crompton.

Moldpro 931 is based on FDA-grade carboxylic acids, and possesses superior organoleptics (no odor and taste).

The additive induces PP crystallization at 129C, said to be comparable or better than DBS products, allowing potential for faster cycles and higher stiffness.

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Haze values obtained in a gas-phase PP homopolymer are better than those with sodium benzoate (39-55% vs. 63%), but not as good as those achieved with the latest generation DBS (12-27%). However, Crompton reports that stiffness with Moldpro 931 is 25% higher in a random copolymer than with a top-end DBS product, while still maintaining impact strength.

PROCESS AIDS

Two process aids from DuPont Dow Elastomers use an optimal combination of rheology-modified fluoroelastomer and innovative interfacial agents to make them work more effectively and efficiently than products currently on the market. Viton FreeFlow Z-100 and Z-200 are used in the production of blown film, cast film, and extruded pipe, wire and cable.

“The technology solves processing problems that other types of additives cannot,” says Christopher Fisher, marketing manager — DuPont Dow.

Both products provide robust processing capability, the ability to reduce die gap size in blown films and reduce die build-up on extruded goods.

Viton FreeFlow Z-200 uses a new interfacial agent. It incorporates polycaprolactone-based technology, which is more oxidatively and thermally stable than polyethylene glycol (PEG). Benefits include virtual elimination of screw slippage, and reduced discoloration.

Axel Plastic Research Laboratories reports that its new process additive, MoldWiz INT-40DHT, has shown significant process gains for resin compounders and pigment masterbatchers. In one recent evaluation, MoldWiz INT-40DHT was credited with improving the processing throughput of a highly filled TPO by 48%.

The additive can also facilitate much higher loading of mineral fillers. It is composed of saturated and unsaturated fatty esters and modified organic acid derivatives.

PVC ADDITIVES

A new class of stabilizer and an unusual lubricant from Crompton Corp. are said to allow high-speed extrusion of rigid PVC window profiles without such common problems as “chatter” lines, die plateout and frictional heat build-up in the calibrator.

Crompton’s new class of organotin heat stabilizers possesses both very high tin content and very high levels of external lubricity. According to Perry Reed, manager of rigid PVC additives at Crompton, the use of these stabilizers alters the profile’s surface tension and die-swell characteristics, allowing the extrudate to pass smoothly through the calibrators at high speed without any chatter.

Manufacturers of profiles and wire and cable can achieve higher throughput rates without compromising the uniformity of pigment distribution using a new black color concentrate for PVC, according to Teknor Color Company.

Designated CS-2001-3 Black, the concentrate has been used successfully in several vinyl processing operations. One profile extrusion company improved output by 20% after switching to the new colorant.

Key to this improved productivity is Teknor Color’s use of a new carbon black pigment that disperses more uniformly and at higher loadings in the PVC carrier resin than conventional carbon blacks.

SPECIAL EFFECTS

Special effects, the most glamorous of additives, remain in the development spotlight.

A luxurious metallic gold effect is possible with Engelhard’s Lumina Brass pigment. The mica-based non-metallic pigment has increased chromaticity, higher color purity and more brightness and hiding power than traditional non-metallic brass colors. The additive incorporates tight particle-size distribution of the mica and a unique multi-layer coating technology.

Silberline metallic pigments are finding more use lately in housewares and automotive applications, notes Eric Greason of Dempsey Corp., which represents the product in Canada. The Silberline metallics are aluminum dispersed in either a polyolefin wax or in plasticizers.

Grades in the High Sparkle series are based on coarse to very coarse non-leafing cornflake pigments that offer a bright, high sparkle appearance.

Ultra High Gloss is a new look from Clariant for personal care packaging. The result of cutting-edge technical and processing research, Ultra High Gloss achieves a superior shine that captures light from all angles. The masterbatch can be formulated for most polyolefins, including polyethylene, polypropylene, SAN and PET. It creates a brilliant reflectivity, especially in multilayer bottles or clear resins.

“We found we could create a container with a shine that is significantly greater than a normal pearlescent white. The light reflects off the entire surface of the bottle,” explains Len Kulka, director of creative development/packaging for Clariant Masterbatches. “We have used this same technique with pastels — blues, pinks — and the results have been impressive.”

PIGMENTS

The most green-shade yellow pigment on the market is Clariant’s new PV Fast Yellow H9G. The pigment is an intense green shade yellow produced by an innovative Clariant proprietary finishing process. It falls into a new color index, Pigment Yellow 214.

“We’ve had a good, positive response from the market,” says Chuck Jones, marketing manager, plastics for Clariant Pigments & Additives. “Its purity and vibrant color will directly benefit masterbatch producers, compounders and colorant suppliers.”

PV Fast Yellow H9G provides excellent heat stability, light fastness and alkali resistance, and it exhibits a low influence on warpage in HDPE.

The pigment is also suitable for use with polyolefins, PVC, styrenics, PMMA, POM and PP. It is heat stable to 280C and FDA-approved for food contact.

New in the line-up for Elementis Pigments are several Ferritan high-heat stable colors. FZ1000 and FZ1500 are zinc ferrite yellows, FM2000 is a manganese ferrite brown and FM2500 is a manganese ferrite black. The Ferritan pigments are formed under high processing temperatures to assure quality and uniformity in plastics applications.

Sachtleben produces a Blanc Fixe product that offers opportunities to cost effectively reduce a portion of pigment demand without changing color values (L,a,b), gloss or opacity. Other Sachtleben products improve the gloss of highly-filled PP compounds. The company is represented in Canada by Canada Colors and Chemicals.

Also from Sachtleben, the Scahtolith product line provides white pigmentation of fibre-reinforced compounds without jeopardizing reinforcement performance.

Millennium Chemicals has developed a highly durable titanium dioxide that retains good optical properties. Tiona 696 is an encapsulated grade targeted for PVC decking, windows and fencing, as well as agricultural films.

To balance the need for good optics and durability, “we use a second additive to improve the durability so we can scale back on the silica encapsulation,” explains Martin J. Painser of Millennium.

The result is that processors can use less Tiona 696 to achieve the durability of current superdurable products.

In addition, the product’s narrow particle size distribution produces higher opacity in thin films. An organic surface treatment provides better wetability for improved dispersion.

Sachtleben now produces nano-sized particles of titanium dioxide called Hombitec. These are small enough to be transparent, but still provide lasting UV protection due to the inorganic chemistry.

OTHER ADDITIVES

Cytec is receiving positive customer response to its new Cyasorb THT light stabilizer technology. Customers confirm that the new materials can replace current HALS products at significantly lower loadings, due to the high efficiency of the TH
T products. Three products are now available in North America (4611, 6435, and 6460), and others will be commercialized in 2003.

C.E.K. Coroplast Enterprises has developed a complete line of blowing agents available in powder, liquid or pellet form. The materials are said to provide high efficiency for extrusion operations. Formulations incorporating coupling agents and endothermic blowing agents are also available for PVC and styrene applications.

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Nano size vs. nano benefits

As nano becomes a new buzzword in additive circles, it’s important to differentiate between products that are merely nano-sized, and products that pack an amazing punch in spite of, or because of, their nano size.

Johanne Denault, who is researching polymer nanocomposites for the NRC’s Industrial Materials Institute (Boucherville, QC) explains:

“A lot of particles that are near 100 nanometers in size are called ‘nano’. But the particles that we are exploring as nano reinforcements have at least one dimension that measures between 1 to 10 nm and the others must be a few microns; the aspect ratio of the nanoparticles is a critical parameter for creating a high performance material. A nano-sized sphere would not provide as much performance benefit as a high-aspect ratio nano-filler.

“With nano-clays, for example, a 2% addition gives as much improvement to the mechanical properties as 30% glass fibres, without the increase in density.”

Because such a small amount of nano-filler is needed, nanocomposite resins can be processed by conventional methods, although some changes in the flow, shrinkage and other thermal properties can be expected.

Homegrown technology leads the way

IMI is putting an emphasis on polymer nanocomposite research, and is trying to establish a special interest group on the subject. “We’ve had good response,” says Denault. “The industry is ready to look at this technology.”

There are currently two producers of nano-clays in the U.S. (Nanocor Inc. and Southern Clay Products Inc.), and several nanocomposite resins available. The materials have made inroads in automotive applications (GM and Toyota) due to their mechanical performance, and in PET bottles and nylon film due to their barrier properties.

Current commercial nanocomposite resins are produced by adding the nano-filler during polymerization. But IMI has already achieved success with melt-blending of nanocomposites, producing a polypropylene nanocomposite with good performance. Denault reports that IMI is pursuing a patent for the process, and is also discussing licensing possibilities.

Looking ahead, Denault also foresees applications for carbon nanotubes in aerospace and other markets. These synthetic materials are currently very expensive but are already finding use in static dissipative and aerospace applications.

Nano-synergy in flame retardants

Nanocor, Inc. and compounder Gitto Global Corporation are expanding their joint development program to create flame resistant polyolefin plastics which incorporate nanotechnology. Nanocor president Peter Maul says, “Gitto Global has already commercialized some nanocomposite plastic compounds which provide significant advantages over traditional flame retardant packages, including greater strength and lower overall weight. With closer cooperation, we expect to see products for a wider variety of polyolefins and the use of nanotechnology in more applications.”

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Shedding Light on Phosporescence

With the advent of long-afterglow phosphorescent pigments, many new applications are opening up for glow-in-the-dark parts.

An emphasis on safety applications is expected in certain markets, reports Victor Satov, product sales manager, polymer additives, Canada Colors and Chemicals. Emergency lighting and signage is one market that could be particularly affected by new glow-in-the-dark (GITD) technology.

Lumilux pigments from Honeywell and LumiNova phosphorescent pigments, distributed by United Mineral & Chemical Corp., are both the new generation, long-afterglow type.

Joe Cameron of RTP Company explained long-afterglow pigments in a paper entitled “Recent trends in glow-in-the-dark coloration anew”, presented at the SPE Color and Appearance Retec in Toronto, September 2002. Excerpts from that paper are presented here.

“Glow-in-the-dark colorants used to be limited to novelty and toy applications. Older ZnS-based pigments have limited glow and are not light fast. Today’s new pigment technology delivers bright, longer lasting luminescence with good light fastness … opening exciting new avenues for the technology.

New rare earth pigments

What is creating the all the excitement today are the new rare earth activated phosphors … which have as much as 10 times brighter luminance and 40 times longer afterglow than the ZnS:x based phosphors.

Europium and Dysprosium Strontium Oxide Aluminate and Alkaline Earthmetal Silicate Aluminate Oxide phosphorescent pigments work best in plastic. These pigments take longer to activate (~30 min. vs. 4 min. for ZnS:Cu). But they glow for 2000 min. or more and the glow brightness is as much as 20 times greater than ZnS:Cu.

The new high-performance GITD pigments are as much as 10 times the cost of the ZnS:x-based phosphors. Fortunately, the new types are much more potent so you can get by with lower loadings and achieve equivalent brightness.

These new higher performance pigments have high hardness and are abrasive, which makes plastic compounding a challenge. The pigment can scour contaminants out of processing equipment and cause quenching of glow properties.

Designing with GITD

Before launching into a laundry list of the many applications for these pigments, you must understand this: you can literally read by the light generated from a plaque molded out of this new material, and it glows all night long.

Safety: vests, road signs, dials, buttons and switches, handles and latches.

Emergency: emergency signage, low-level lighting of escape routes, life rafts and vests.

Take emergency lighting as an example. Rather than an electric light with power source and battery backup, the GITD equivalent can be made from extruded sheet … laser marked. Often as thin as poster board, they are easy to mount (double-stick tape works for most exits) and they require no backup power.”


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