POLYMER REINFORCED MATERIALS FOR INKJET BASED 3D PRINTING

Abstract

The present disclosure relates to reinforcing photopolymer resins and uses thereof, e.g., in inkjet 3D printing.

Claims

1. A reinforced composition for 3-D ink printing, said reinforced composition comprising: a UV-curable matrix material and a reinforcing agent, wherein the reinforcing agent is at least partially soluble in the UV-curable matrix material and wherein the solubility of the reinforcing agent in the UV-curable matrix material decreases as the UV-curable matrix material cures, whereby curing the UV-curable matrix material causes the reinforcing agent to form a phase-separate domain in the cured UV-curable matrix material.

2. The reinforced composition of claim 1, wherein the UV-curable matrix material comprises an acrylate.

3. The reinforced composition of claim 1, wherein the UV-curable matrix material comprises a thiol-ene.

4. The reinforced composition of claim 1, wherein the UV-curable matrix material comprises a combination of acrylate and thiol-ene.

5. The reinforced composition of claim 1, wherein reinforcing agent is selected based at least in part on a property of the UV-curable matrix material.

6. The reinforced composition of claim 1, wherein the reinforcing agent has a higher glass-transition temperature than that of the UV-curable matrix material.

7. The reinforced composition of claim 1, wherein the reinforcing agent is non-UV-curable.

8. The reinforced composition of claim 1, wherein the reinforcing agent and UV-curable matrix material fail to react with each other.

9. The reinforced composition of claim 1, wherein the cured reinforced composition is 30-300% has a tensile strength that is higher than that of the UV-curable matrix material in the absence of the reinforcing agent.

10. The reinforced composition of claim 1, wherein the cured reinforced composition has a tensile strength that depends upon loading of the reinforcing agent within the reinforced composition.

11. The reinforced composition of claim 1, wherein the reinforcing agent is present in an amount that is less than 20 wt %.

12. The reinforced composition of claim 1, wherein the reinforcing agent is a polyvinylpyrrolidone.

13. The reinforced composition of claim 1, wherein the reinforcing agent is a poly(methyl methacrylate).

14. A method comprising jetting a layer of ink onto a structure that is being printed and causing dissolved reinforcing agent to precipitate after said layer of ink has been deposited.

15. The method of claim 14, wherein causing said dissolved reinforcing agent to precipitate comprises curing said ink.

16. The method of claim 15, wherein curing said ink comprises exposing said ink to UV.

17. The method of claim 15, wherein curing said ink comprises exposing said ink to a temperature decrease.

Description

DESCRIPTION OF A PREFERRED EMBODIMENT

[0034] A composition of the 3D printable material includes a printable matrix material, which is curable, and a reinforcing agent. The printable matrix material is typically a monomer that polymerizes under UV irradiation. The printable matrix material is generally, but not limited to, acrylates, thiol-enes or combinations thereof.

[0035] The reinforcing agent is not UV-curable and is non-reactive with the printable matrix material. The reinforcing agent is, however, at least partially soluble in the printable matrix material. The reinforcing agent and the printable matrix material may be mixed as liquids, or the reinforcing agent may be dissolved as a solid into the liquid printable matrix material to form a solution. The reinforcing agent has a higher glass transition temperature (Tg) than the printable matrix material. In one embodiment, the reinforcing agent constitutes less than 20% of the matrix material-reinforcing solution by weight.

[0036] Although the reinforcing agent is at least partially soluble in the printable matrix material, as the printable matrix material is cured under UV irradiation or otherwise undergoes a temperature decrease, the reinforcing agent becomes less soluble and precipitates out of solution forming another phase within the printable matrix material. This phase forms reinforcing structures within the curing matrix material.

[0037] The principle may be understood by considering the following non-limiting examples.

EXAMPLE 1

Material: Acrylate Matrix Reinforced by a Vinylpyrrolidone

[0038] In this embodiment, IPUC101, an inventor-formulated elastomeric acrylate material, is reinforced by Polyvinylpyrrolidone (PVP) (Mw: 6000-150000). IPUC101 is a self-formulated (see Table 1), elastomeric acrylate material with a tensile strength of 3.4 MPa, elongation at break of 160%, and Shore hardness of 35A. The reinforcing agent is Polyvinylpyrrolidone (PVP) K15, purchased from Tokyo Chemical Industry Co. Ltd. The reinforcing agent PVP is a polymer known for having high polarity. Because this formulation of IPUC101 includes almost 30% 2-Hydroxyethyl acrylate (HEA), IPUC101 is also polar to some extent. The HEA in the IPUC101 helps the PVP to dissolve or disperse into the uncured material. The reinforcing effect on IPUC101 is a function of both the composition of reinforcing agent and the concentration of the reinforcing agent. In this embodiment using PVP, the molecular weight was shown to have a large effect on the reinforcement.

Preparation of PVP-Rein Forced IPUC101

[0039] In one embodiment, the desired amount of PVP and IPUC101 were dispensed into a sealed amber bottle. The mixture was stirred at elevated temperature (for example 70° C.) until all solids were dissolved. In another embodiment, the PVP powder and IPUC101 were added into a container and mixed using a Flextek mixer (Flex-Tek Group, Greenwood, S.C., USA) at room temperature until the powder was uniformly dissolved in the solution. Each resulting solution was either clear or slightly cloudy. The inks were stored at room temperature until use.

[0040] The reinforcing effect of adding PVP K15 to the IPUC101 formulation is shown in Table 2. The tensile strength and Shore hardness of the material increases as PVP K15 is added to the formulation. The tensile strength of the IPUC101 material without PVP is 3.4 MPa, but increases to 4.6, 7.4, and 9.6 MPa at loading fractions of 1.5%, 3%, and 5% PVP K15 respectively. The Shore A hardness similarly increases from 35 to 38, 40, and 45 respectively. Notably, the elongation at break does not appear to change significantly. Also, of note is the degree of reinforcement at low loading fraction. Typical fillers require 30-100 phr for adequate reinforcement, whereas PVP K15 reinforcement more than doubles the tensile strength at only 3% loading.

TABLE-US-00001 TABLE 1 IPUC101 Formulation Percentage Supplier Function Photomer 6230 29.98 IGM Resins Oligomer 2-Hydroxyethyl acrylate 29 TCI America Monomer SR440 20 Sartomer Monomer Genomer 1121 20 Rahn AG Monomer Omnirad 819 1 IGM Resins Photo initiator MEHQ 0.02 Sigma Photo inhibitor Total 100

TABLE-US-00002 TABLE 2 With and Without PVP K15 Reinforcement: Mechanical Properties Tensile Elongation at Hardness strength (MPa) break (%) (Shore A) IPUC101 3.4 160 35 IPUC101 − 1.5% K15 4.6 162 38 IPUC101 − 3% K15 7.4 166 40 IPUC101 − 5% K15 9.6 160 45
Table 3 below shows how viscosity of the acrylate resin IPUC101 formulation as a function of temperature without any reinforcing filler as well as with varying amounts of reinforcing filler.

TABLE-US-00003 IPUC101 + IPUC101 + IPUC101 + IPUC101 1.5% K-15 3% K-15 5% K-15 30 C. 30.70 cP 36.65 cP 43.17 cP 49.31 cP 40 C. 20.76 cP 24.66 cP 28.78 cP 31.81 cP 50 C. 14.89 cP 17.46 cP 20.19 cP 22.83 cP 60 C. 11.30 cP 13.09 cP 14.85 cP 16.58 cP 70 C.  8.48 cP  9.82 cP 11.24 cP 12.55 cP

EXAMPLE 2

Material: Acrylate Matrix Reinforced by a Second Vinylpyrrolidone

[0041] In this embodiment, the vinylpyrrolidone is Polyvinylpyrrolidone K12 provided by BASF. The preparation of samples of IPUC101 reinforced with PVP K12 is the same with IPUC101 reinforced by PVP K15 (Mw: 4000-6000). The mechanical properties of PVP K12 reinforced IPUC101 is shown in Table 3. As shown in Table 3, with 5 wt % of loading, there is a 40% of increase in tensile strength. Although the tensile strength was increased, the increase is not as significant as when PVP K15 is the reinforcing agent.

TABLE-US-00004 TABLE 3 PVP K12 Reinforcement: Mechanical Properties Tensile Elongation at Hardness strength (MPa) break (%) (Shore A) IPUC101 3.4 160 35 IPUC101 − 3% K12 3.7 156 40 IPUC101 − 5% K12 4.9 161 40

EXAMPLE 3

Material: Thiol-ene Matrix Reinforced by Poly(Methyl Methacrylate) PMMA

[0042] In this embodiment, a new Thiol-ene matrix material, TE14, is a self-formulated (see table 4), elastomeric thiol-ene material with a tensile strength of 1 MPa, elongation at break of 107%, and Shore hardness of 30 A. The reinforcing material PMMA (Mw: 120000) was purchased from Sigma.

TABLE-US-00005 TABLE 4 TE14 Formulation Percentage Supplier Function Trimethylolpropane tris(3- 15.15 Sigma Monomer mercaptopropionate) 3,6-dioxa-1,8- 29.6 TCI America Monomer octanedithiol Diallyl phthalate 53.7 TCI America Monomer Vinylphosphonic acid 0.5 TCI America Photo inhibitor Omnirad 651 1 IGM Resins Photo initiator Pyrogallol 0.05 TCI America Photo inhibitor Total 100

Preparation of TE14 Reinforced by PMMA

[0043] In this embodiment, a desired amount of each of PMMA and TE14 was dispensed into a sealed amber bottle. The mixture was stirred at elevated temperature (for example 70° C.) until all solids were dissolved. Alternatively, PMMA powder and TE14 were added into a container and mixed through a Flextek mixer at room temperature until the powder was dissolved in the solution. The resultant solutions were clear. The composition was stored at room temperature until use.

[0044] The reinforcing effect of adding PMMA to the TE14 formulation is shown in Table 5. The tensile strength and Shore hardness of the material increases as PMMA is added to the formulation.

TABLE-US-00006 TABLE 5 Reinforcing Effect of Adding PMMA to the TE14 Formulation Tensile Elongation at Hardness strength (MPa) break (%) (Shore A) TE14 1.0 107 30 TE14 − 3% PMMA 1.3 236 32 TE14 − 5% PMMA 1.7 184 35

[0045] A number of implementations have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the disclosure. For example, various forms of the materials shown above may be used, with steps re-ordered, added, or removed. Accordingly, other implementations are within the scope of the following claims.

[0046] The examples presented herein are intended to illustrate potential and specific implementations of the present disclosure. The examples are intended primarily for purposes of illustration of the invention for those skilled in the art. No particular aspect or aspects of the examples are necessarily intended to limit the scope of the present invention.

[0047] The figures and descriptions of the present invention have been simplified to illustrate elements that are relevant for a clear understanding of the present invention, while eliminating, for purposes of clarity, other elements. Those of ordinary skill in the art may recognize, however, that these sorts of focused discussions would not facilitate a better understanding of the present disclosure, and therefore, a more detailed description of such elements is not provided herein.

[0048] Unless otherwise indicated, all numbers expressing lengths, widths, depths, or other dimensions and so forth used in the specification and claims are to be understood in all instances as indicating both the exact values as shown and as being modified by the term “about.” As used herein, the term “about” refers to a ±10% variation from the nominal value. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Any specific value may vary by 20%.

[0049] The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The foregoing embodiments are therefore to be considered in all respects illustrative rather than limiting on the invention described herein. Scope of the invention is thus indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are intended to be embraced therein.

[0050] It will be appreciated by those skilled in the art that various modifications and changes may be made without departing from the scope of the described technology. Such modifications and changes are intended to fall within the scope of the embodiments that are described. It will also be appreciated by those of skill in the art that features included in one embodiment are interchangeable with other embodiments; and that one or more features from a depicted embodiment can be included with other depicted embodiments in any combination.