COMPOSITION FOR USE IN 3D PRINTING

Abstract

A photocurable polymer composition for use with a three dimensional printing process and a method of manufacture of such composition. The composition includes a photocurable resin and a filler and can be tunable to a desired dielectric constant. The filler comprises about 0 to about 30 weight percent of the composition.

Claims

1. A photocurable polymer composition for use in a three-dimensional printer comprising: a photocurable resin; a filler; wherein said filler ranges from About 0 to about 30 weight percent of the composition and said photocurable polymer composition has a desired dielectric constant.

2. The composition as recited in claim 1, whereOIN the photocurable resin is an acrylate.

3. The composition as recited in claim 1, wherein the photocurable resin is an olefin.

4. The composition as recited in claim 1, wherein the filler is chosen from the group consisting of inorganic or organic fillers.

5. The composition as recited in claim 3, wherein the inorganic fillers are chosen from the group comprising of mica, titanium dioxide and magnesium oxide.

6. The composition as recited in claim 4, wherein the fillers comprise a mixture of mica and magnesium oxide.

7. A method of preparing a photocurable composition having a desired dielectric constant for use in a three-dimensional printer comprising adding filler to a photocurable resin and dispersing uniformly the filler in such photocurable resin.

8. A part manufactured using a three-dimensional printer using a photocurable composition comprising a photocurable resin with filler dispersed uniformly in such resin to achieve a desired dielectric constant.

9. The composition of claim 1, wherein the photocurable resin is an epoxy.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] FIG. 1 is a flow diagram of an illustrative process of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0018] The description of illustrative embodiments according to principles of the present invention is intended to be read in connection with the accompanying drawings, which are to be considered part of the entire written description. In the description of embodiments of the invention disclosed herein, any reference to direction or orientation is merely intended for convenience of description and is not intended in any way to limit the scope of the present invention. Relative terms such as “lower,” “upper,” “horizontal,” “vertical,” “above,” “below,” “up,” “down,” “top” and “bottom” as well as derivative thereof (e.g., “horizontally,” “downwardly,” “upwardly,” etc.) should be construed to refer to the orientation as then described or as shown in the drawing under discussion. These relative terms are for convenience of description only and do not require that the apparatus be constructed or operated in a particular orientation unless explicitly indicated as such. Terms such as “attached,” “affixed,” “connected,” “coupled,” “interconnected,” and similar refer to a relationship wherein structures are secured or attached to one another either directly or indirectly through intervening structures, as well as both movable or rigid attachments or relationships, unless expressly described otherwise.

[0019] Moreover, the features and benefits of the invention are illustrated by reference to the preferred embodiments. Accordingly, the invention expressly should not be limited to such embodiments illustrating some possible non- limiting combination of features that may exist alone or in other combinations of features, the scope of the invention being defined by the claims appended hereto.

[0020] The present invention relates to a novel photocurable polymer composition for use in three-dimensional printing which is tunable to a desired dielectric constant. The novel photocurable polymer composition comprises a photocurable resin with fillers dispersed in the photocurable resin. The novel photocurable polymer composition can be tuned to achieve the desired dielectric constant.

[0021] The dielectric constant of a material may be important for the desired end use of the material. The dielectric constant (k) of a material is the ratio of its permittivity to the permittivity of vacuum. Consequently, the dielectric constant is therefore known as the relative permittivity of the material. A low-k dielectric material is a material that has a low ability to polarize or hold a charge. Low-k dielectric materials are generally good insulators. Low-k dielectric materials are preferred for high frequency or power applications to minimize electric power loss. High k-dielectric materials are good at holding a charge and are preferred materials for capacitors, or memory cells that store digital data in the form of a charge. The desired dielectric constant is determined based upon the end application of the novel photocurable polymer composition. Such determination is well within the skill of one of ordinary skill in the art.

[0022] Any photocurable resin that can be used in 3D printers can be used in this invention, including but not limited to UV curable olefins, UV curable epoxies and UV curable acrylates. Most preferably, the photocurable resin is based upon an acrylate. Alternatively, the photocurable resin can be a modified acrylate in which the backbone of the acrylate is modified to make it UV curable. Examples of such modified acrylates include epoxies or cyanate esters.

[0023] Examples of suitable photocurable resins that are commercially available include HT300 available from 3D Systems; CE 221 available from Carbon 3D; and Tough Black resin available from 3D Systems.

[0024] To achieve the desired dielectric constant, fillers are added to the photocurable resin. The desired dielectric constant is determined by the end use of the composition. Preferably, the dielectric constant is in the range of about 2.0 to about 5.9. The fillers are selected based upon the desired dielectric, the ability of the filler to disperse in the base resin, as well as printability of the composition. Fillers that agglomerate in the photocurable resin are not desired or preferred. In one embodiment, the filler is selected to achieve a target dielectric constant of about 3.8 with printability. Fillers may be selected to achieve other desired dielectric constants.

[0025] There are possibly two types of fillers that can be used in the composition: organic fillers and inorganic fillers. Examples of organic fillers include polyethylene (PE), polytetrafluoroethylene (PTFE), and polybutylene terephthalate (PBT). Examples of inorganic fillers include mica, magnesium oxide (MgO) and titanium dioxide (TiO.sub.2). Preferred filler size and morphology will vary based upon the base resin and the filler combination. In one embodiment, a PE powder ranging in size from 40-48 micron was used, while in another embodiment, mica flake and MgO powder, both 325 mesh were used.

[0026] The range of the filler in the photocurable polymer composition is about 15 weight percent to about 40 weight percent. A single filler can be used in the photocurable polymer composition. However, it has however been found that a mixture of fillers enhances the electrical properties of the photocurable polymer composition while optimizing printability. An example of a mixture of fillers that can be used is a mixture (weight percent) of 28-32% mica and 8-12% magnesium oxide. To enhance printability, 10-15% titanium dioxide, 0.05-1% mica and 0.050-1% magnesium oxide can be used.

[0027] The photocurable polymer composition of the instant invention is formulated as shown by the block flow diagram of FIG.1. Liquid photocurable resin is added to a vessel. This step is shown as 10 in FIG.1. Filler is then added to the vessel as shown at 20 in FIG. 1. If more than one type of filler is used to make the photocurable polymer composition, the filler can all be combined by dry blending prior to the addition of the filler to the liquid resin. The liquid resin is then mixed with the fillers using centrifugal mixing so one can see that the filler is uniformly dispersed in the composition as shown at 30 in FIG.1. If there are issues with the uniformity of the mixture, dispersants such as polyacrylic acids may be added as an aid to the process. An example of a suitable dispersant is Dispex, available from BASF. Alternately, or in addition to the dispersant, a compatibilizer containing glycidyl methacrylate may also optionally be added to the composition. An example of such a compatibilizer is Lotader AX 8840 available from Arkema.

[0028] The time for mixing the resin with the filler is dependent upon the filler material. Care must be taken to make sure that heat is not generated during the process and crosslinking of the resin does not occur. The exact conditions for such mixing are well within the scope of one of ordinary skill in the art. A final photocurable composition is obtained as shown in 40 in FIG.1.

[0029] An example of a suitable mixer to be used in the process is a centrifugal mixer called a Flacktek speed mixer. Any other mixer which can uniformly disperse the filler in the resin can be used in the process.

[0030] The photocurable polymer composition can be processed into various objects using a DLP printer or a SLA printer. Examples of suitable DLP printers include FIG. 4 printers from 3D Systems. The Viper System or the Form 2 printer is an example of an SLA printer that can be used. The settings used to process the photocurable composition in these printers can be easily determined by one of ordinary skill in the art.

[0031] One skilled in the art will appreciate that the invention may be used with many modifications of structure, arrangement, proportions, sizes, materials and components and otherwise used in the practice of the invention, which are particularly adapted to specific environments and operative requirements without departing from the principles of the present invention. The presently disclosed embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being defined by the appended claims, and not limited to the foregoing description or embodiments.