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Developments in Water-Soluble Supplies for 3D Printing Assist Filament – 3DPrint.com

Advancements in Water-Soluble Materials for 3D Printing Support Filament - 3DPrint.com

A new material has been developed that is ideally suited as a water-soluble all-purpose carrier for additive manufacturing (3D printing). Its thermal stability and robust adhesive properties make it an ideal carrier system for a wide variety of building materials.

Most manufacturers know how 3D printing enables them to make stronger and lighter parts and systems. Although many different materials can be used to create 3D printed models, the most common thermoplastics used are acrylonitrile butadiene styrene (ABS), polylactic acid (PLA), and polycarbonate (PC).

Complex thermoplastic parts and structures have bridges or overhangs that need to be supported while printing. Since these supports are not part of the model, they must be removed after printing. This post-processing step is important as it affects the final surface finish, strength, and color of the printed part. However, it can be tedious, require the use of harmful chemicals, damage the surface of the model, and decrease productivity. For this reason, it is important to choose the right material for 3D printing support structures.

BREAKAWAY VS. SOLUBLE SUPPORT STRUCTURES

There are two basic categories of materials available for support structures: breakable and soluble. Tear-off support structures are often made from a material that is similar to the printed object. After printing, the carrier is removed by trimming, mechanical breaking or abrasion.

All of these steps add to the labor, and therefore the time and cost of each piece. In addition, removing the 3D printing support structures can leave imperfections on the model surface or break part of the model along with the structure. Also, tear-off props are generally more difficult to remove when working with high temperature materials.

Alternatively, soluble substrates can be removed by adding them to water or a solvent after printing. The use of solvents is undesirable because they are generally volatile organic compounds that are unfriendly to printers and the environment. However, it can also be difficult to work with water-soluble carrier materials. For example, polyvinyl alcohol (PVA) absorbs water vapor from the air, does not adhere very well to printing surfaces, and is temperature sensitive, which can lead to jams. Water-soluble support materials were also extremely difficult to develop.

DEVELOPMENT CHALLENGES FOR SOLUBLE SUPPORTS

The development of water soluble carriers is challenging for many reasons. First, there are a limited number of commercially available resins that are truly water soluble. Many water-soluble polymers are very brittle, which prevents them from converting into filaments. In addition, plasticizing with conventional additives often inhibits thermal stability and adhesion, which severely limits their use in 3D printing.

The first generation of soluble carriers had a number of problems. Some used harmful chemicals or strongly acidic or strongly basic solutions. While some of these are still widely used, resin technology has advanced and there are now a variety of soluble substrates in the commercial market including:

• Highly proprietary resins (Stratasys SR30, SR35, SR100, etc.)

• Resins based on commercially available PVA or polyvinylpyrrolidone (PVP)

• Cellulosic agents such as hydropropylmethyl cellulose (HPMC)

• Exotic polybutenediol vinyl alcohol (BVOH)

However, none of these products are ideal for filaments because they are not thermally stable. Now there is a better material option.

WATER-SOLUBLE RESINS THAT ARE HEAVY ON THE FILAMENT

Infinite Material Solutions recently developed a composite material that is both water soluble and thermally stable. This “out of the box” resin is formulated from a naturally occurring carbohydrate blended with a polymer that is flexible, tough, and water soluble. The new material (branded) AquaSys120) is unique in that it is sturdy enough to be used as a support filament.

This formulation is surprising, since many pure carbohydrates and water-soluble polymers are far too brittle to form a usable filament. Over the years, formulators have made many attempts to plasticize water soluble resins so that they can be converted into filaments. However, the addition of plasticizers often dramatically reduces the thermal stability of the base resin. Plasticizers can also inhibit the adhesion between materials and severely limit their use for 3D printing. AquaSys 120 uses a highly complex process to produce filaments 1.75mm and 2.85mm in diameter that can be successfully used for a wide variety of 3D printing platforms and materials.

MATERIAL ADVANTAGES AND COMPATIBILITY

The individual components of this new material are widely used in industry for a wide variety of applications ranging from packaging and drug delivery to cosmetics and personal care products. The material is hydrophilic, biocompatible, biodegradable, non-toxic and non-carcinogenic based on information available for each individual component.

This new filament material can be used for the most popular 3D printing technologies, including the manufacture of melt filaments and direct material extrusion. It is also compatible with a wide variety of materials including polypropylene, as well as hydrophilic and hydrophobic polymers. It shows excellent thermal stability and other advantages over traditional PVA that make it a more versatile, robust and environmentally friendly material for carrier filaments.

These benefits include:

• Dissolves in water much faster than pure PVA

• Can be printed with a wider range of materials

• Has improved adhesion properties

• Will biodegrade faster than PVA

THERMAL STABILITY AT MUCH HIGHER TEMPERATURES

A leading brand of PVA filament printing at 215-225ºC and a maximum build plate temperature of 60ºC. Alternatively, the AquaSys 120 filament prints at 240-245ºC and a maximum building board temperature of 130ºC.

ADHESION PROPERTIES

The ability to create materials that can adhere to soluble substrates, or vice versa, is critical to successful 3D printing. Poor adhesion between adjacent carrier and building material layers leads to flaking and printing defects.

The new material was developed with improved adhesion properties to address this problem. It is compatible with a wide variety of hydrophobic and hydrophilic materials used in filament-driven 3D printing platforms and continues to be used with new building materials.

Til today AquaSys 120 has been successfully printed with polyamides (nylon), co-polyester (CPE), acrylonitrile butadiene styrene (ABS), thermoplastic polyurethane (TPU), polycarbonate (PC) and polyolefins such as polypropylene (PP). This offers a significant advantage over conventional PVA filaments, which have limited adhesion to CPE, ABS, TPU, PC and PP.

RESOLUTION

In head-to-head dissolution tests with identically printed parts, the new filament material dissolved twice as fast as a leading brand of PVA at room temperature (22 ° C) and more than six times faster at elevated temperatures (80 ° C). 1 shows its kinetics of dissolution against PVA. In contrast to PVA, which can form gels before dissolving and especially at elevated temperatures, the new material dissolves cleanly and without gelation at temperatures> 35 ° C.

DISPOSAL AND BIODEGRADABILITY

The new composite material is based on a naturally occurring carbohydrate that is mineralized very quickly in the environment. The mineralization of this carbohydrate component can take several hours or days. The remaining constituents of the material biodegrade more slowly, but like PVA, they are considered ultimately biodegradable based on respiratory mineralization tests using acclimated sludge from sewage treatment plants.

A new water-soluble carrier material is now available that solves a number of challenging problems in additive manufacturing. This carbohydrate compound takes advantage of the unusual thermal stability and excellent water solubility of a naturally occurring saccharide mixed with a flexible and tough water-soluble polymer. This unique material offers advanced adhesion to a wide variety of building materials, a wide processing window and improved dissolution performance in water without the use of solvents or harsh chemicals.

By: Nathan W. Ockwig, Gavriel DePrenger-Gottfried, Brandon Cernohous, Philip J. Brunner and Jeffrey J. Cernohous

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