NewMat engineering plastics must be dried before molding. Drying can be done through an ordinary hot air circulating dryer or a dehumidifier. For best results, choose the latter.

Startup and Shutdown

The startup procedure is similar to that of other thermoplastics; first set the hopper and nozzle temperature to the desired melting temperature.

For caution’s sake, purge the melt resin generated during the heating stage. Test again to determine optimal mold parameters.

Prior to long-term shutdown, empty all remaining material inside the hopper.

Use of Recycled Materials

In molding NewMat engineering plastics, runners and scrap produced can be recycled. While the ratio of recycled material should be determined in accordance with the specific test results and quality requirements, the recycled ratio is generally limited to 25%.

Recycled material must be clean and dry.  It should be dried again before molding, even when it has been stored in a dry place.  Moisture in the molding process will result in material degradation.

Note: When recycled materials are added to the new material it will cause variations in the melt rheological properties, demolding, shrinkage and the mechanical properties of the product.

Injection Molding Conditions

Molding Temperature (oC) / Time (hour):

Mold Temperature

The mold temperature of NewMat engineering plastics is typically between 80 and 100℃, while the mold temperature required by for the CP1201and DK series is lower than 40℃.

Appropriate control on mold temperature is an important condition for obtaining a highquality product.

Mold temperature impacts the final products in a number of ways including surface glossiness, dimensional tolerance, deformation, and internal stress etc.

Duration in Hopper

Plastic degradation takes place in high temperature environment.

The length of time in which the plastic remains in the hopper is a determining factor of product quality. If the time is too short, it may cause inadequate plasticization; if the time is too long, it may cause thermal degradation.

Thermal degradation will lower the product’s impact strength, cause discoloration, flow marks and other such undesirable qualities.

A variety of printing processes can be used to decorate injection molded, extruded and thermoplastic products, and as the manufacturer for many branded copolyester materials such as Eastar, Spector, Eastapak and Eastalloy, Eastman recommends that you select a printing supplier with relevant experience including selection of ink and printing process, and recommends you to strike a balance between the cost and quality of printing.

Printing ink and base material thermoplastic products that are waterproof with non-porous surfaces typically require specific ink formulations to attain rapid drying and strong adhesion, solvent-based, water-solubility and ultraviolet-based inks. Corona curable printing inks can be used for printing most plastic materials. Enamel, epoxy, acrylic acid and ester and polyurethane-based inks are often used as well.

If the surface tension of the ink is lower than the surface tension of the surface of material to be decorated, the printing ink will give a more pleasing wet effect. Eastar PETG has a higher surface tension that Eastapak PET so PETG offers better printability than PET.

In general, the surface tension of water-base dink is higher than solvent-based ink. Diluting the ink with alcohol can reduce the surface tension of water-base dink and therefore improve the printability of the ink.

Corona surface treatment can be used on copolyester materials of lower surface tension. The treatment can increase the surface tension and polarity on the surface, thereby improving printability.

Chemical resistance

Some inks with strong solvent base may cause surface corrosion which appears to show cracking, embrittlement or swelling. In order to reduce the chance of corrosion, a mild solvent such as mineral spirits, polycyclic aromatic hydrocarbons and naphtha could be added to the inks.

Curing Time

When using UV-curable inks in color printing, short curing time will avoid over-curing which may lead to a brittle ink layer and adversely affect the toughness of coating.

Abrasive Resistance

The use of shiny ink varnish or wax may improve the abrasive resistance of the surface.

Static Control

When printing on the surface of thermoplastics, static control is an important tissue. However, overly-sensitive control may impact productivity. During inkjet, laser and other such printing processes, static electricity can cause instability of the ink supply. The use of an elimination-style workshop can protect the base material through deionized air, solving these problems.

Pad Printing

Pad printing is a high-quality printing option for irregular or etched surfaces. This technology is ideal for printing on the surface of injection molded, extruded or other such thermoplastic parts, also ideal for single or multiple color printing. Output can be high or low.

So-called pad printing is the use of concave copper or steel plates, with a silicone rubber pad on top of a casted, hemispherical-shaped head. By pressing the silicone pad to the substrate, the image is transferred onto another object.

Pad printing uses a liquid ink that is directly printed onto the plastic base material. Then another coating of UV-curable ink is printed on the previous ink layer (wet-on-wet). Compared to screen printing, pad printing can achieve a much thinner ink layer.

Pad printing technology has been proven on the printing of Spectar and Eastalloy polymers.

Screen Printing

Simply put, screen printing is technique through a woven mesh supporting an ink-blocking stencil. It utilizes the adhesion of printing ink forced through the ink-passing openings on the screen to form a design pattern. The screen is made of synthetic fibers such as polyester, nylon or very fine stainless steel wire mesh. The screen is initially covered with an impermeable photosensitive substance, and a printable pattern is generated through exposure. The pattern is then directly painted upon the plastic substrate by forcing a highly adhesive ink across the screen openings with squeegee. As the ink has high adhesion and surface tension, the surface tension of the substrate does not have a significant impact on the printing results.

Screen printing is suitable for situation when clean, clear, high-detailed reproductions are required. It is ideal for design with a variety of font patterns. There is no limit as to the size of patterns. It offers good color reproducibility and it has other advantages of low cost printing plates, simple and cost effective operations. This technique is widely used for multiple colored plastic parts designed for short-to-medium term usage.

Screen printing has already been successfully applied to Spectar and Eastalloy polymers.

Offset Lithography, Letterpress and Gravure Printing

Offset lithography, letterpress printing and gravure printing are typically used in extruded products. Offset lithography is to use an intermediate–a rubber roller to transfer the printed pattern; gravure and letterpress printing directly print the pattern onto the substrate through printing plates so that the supply of substrate can either be continuous or intermittent.

Eastar and Spectar copolyester substrates can be printed with these printing techniques. Laser Printing

This technology is often applied for high-quality permanent product labels such as bar codes, digital patterns, serial numbers and lot numbers.

There is a major difference between laser printing and laser engraving: laser engraving evaporates certain sections of the base material while laser printing uses heat generated by laser to instantly and permanently discolor the plastic. Laser printing might be challenging for copolyester because laser may penetrate transparent materials which may lead to bubbling or burn in Eastar and Eastalloy copolyester.

Stamping and thermal transfers can be used for glossy or textured surfaces of injected, extruded and thermoplastic products. These decorative methods have been proven successfully on Eastman’s Spectra® and Eastalloy® polymers.

Stamping

Stamping is the use of hot tool engraved with text or design patterns, by which the color of metallic foil can be transferred onto the product surface under a certain pressure, thereby obtaining fine patterns or text. Stamping is popular because it can be used for many different colors, with good persistence and beautiful products, not to mention that this method is both simple and economic.

Thermal Transfer

This method uses a special thermally conductive silicone rubber to print a heat-transferred label or logo onto the product. The print effect of thermal transfer can be very colorful.

Abrasive and Chemical Resistance

If a protective layer is added to the stamping foils or thermal transferred labels, it will improve the abrasive resistance and chemical resistance of the printed surface. Using high pressure to create recessed foils and labels below the product surface can also improve abrasive resistance.

Hot Pressing Conditions

Hot pressing conditions should follow material supplier’s recommendations or be verified through testing. As for copolyesters, we recommend a nozzle temperature of 149℃-204℃, a residence time of 1-2 seconds and a pressure of 0.62MPa.