TW202003206A - Layer-by-layer production methods with selective curing - Google Patents

Abstract

Layer-by-layer methods for producing three-dimensional objects are described. The methods include selective curing steps in which, for at least some layers, all boundaries of the object are cured and remaining portions of the object are selectively-cured. As a result, a least a portion of those layers remains uncured prior to formation of the subsequent layer. In some embodiments, these methods include steps to limit the amount of uncured resin in the final object.

Description

Layer-by-layer production method using selective curing

The present disclosure relates to the production of three-dimensional objects layer by layer from a curable composition. The method of the present disclosure includes selectively curing at least some layers so that portions of these layers remain uncured before forming one or more subsequent layers. Steps for further controlling the amount of uncured resin in the final object are also disclosed.

In many additive or three-dimensional ("3D") manufacturing processes, each individual layer is a photocurable resin located in an area sometimes referred to as a "build plane" by irradiation and curing. Generally, the construction plane is a layer extending in the X and Y dimensions perpendicular to the illumination direction. The radiation penetrates to some depth called the Z direction, defining the thickness of the layer. The depth of penetration (and thus the thickness of the layer) is on the order of less than the X dimension and Y dimension, so that the layer is essentially a 2-dimensional plane.

There are various types of layer-by-layer three-dimensional manufacturing procedures, and the method of the present disclosure can be used in any such procedure. Therefore, the details of specific manufacturing techniques are provided to provide the background and elements of the description method, but those with ordinary knowledge in the technical field can easily apply them to any layer-by-layer manufacturing technology, including stepwise and continuous liquid interface production (continuous liquid interface production) production, "CLIP") program.

For example, in traditional photo-curing polymerization techniques, the object system is created in a "top down" procedure, where each new layer is formed on top of the previously cured layer. In reverse photocuring polymerization technology, the object system is created in a "bottom up" procedure, in which new layers are formed at the bottom of the previously cured layer.

In general, the composition used in the 3D manufacturing process has been composed of photocurable resins and optionally nonvolatile additives such as fillers. In such applications, the intention is to retain the cured resin and filler in the finished object. However, the range of materials that can be manufactured in 3D has been expanded and now includes a composition that removes the photocurable resin from the object after the 3D construction process. For example, photocurable resin can be used as a carrier for other components. When cured in the 3D manufacturing process, the resin is used as a matrix to keep other components in the desired shape. In the subsequent steps, the cured resin can be removed, for example, by dissolving or burning off the resin. In order to retain the desired shape of the object, one or more of the other components are hardened (eg, cured or sintered) before or during the matrix resin removal procedure.

For example, WO 2017/127561 A1 ("Additive Process of Fluoropolymers") describes a 3D printable composition for making shaped fluoropolymer articles. Such a composition may include a fluoropolymer dispersed in a polymerizable binder material. These compositions may also include solvents (eg, water) that produce colloids (eg, hydrogels). In the subsequent processing steps, the solvent is removed (eg, it is evaporated), the binder is burned off, and the remaining fluoropolymer particles are sintered to form a finished product.

In short, in one aspect, the present disclosure provides a layer-by-layer method for forming a three-dimensional object from a composition including a polymerizable material. The three-dimensional object includes internal layers, and the internal layers include an array of stereo pixels. The array includes boundary stereo pixels and closed stereo pixels. The closed stereo pixels correspond to one of the three-dimensional objects delimited by the boundary stereo pixels. Cross-sectional area. Each stereo pixel in a layer has a width W and a length L measured along an orthogonal axis in the plane of the layer, and each layer has a thickness T measured perpendicular to the layer.

The method of the present disclosure includes a selective curing step, which includes: providing an uncured layer of the composition in a construction area; identifying closed stereo pixels selected for curing and selected to maintain uncured closed stereo Pixels; creating a selective curing layer by curing the polymerizable material in the boundary stereo pixels; and curing the polymerizable material in the closed stereo pixels selected for curing, wherein the selected The closed stereoscopic pixels for curing include less than all of the closed stereopixels; and translating the selective curing layer to recreate the construction area; wherein curing the polymerizable material includes irradiating the composition in the construction area to a curing depth D, where D is greater than or equal to T.

In some embodiments, the methods further include repeating the selective curing step N times to form N consecutive selective curing layers, where D is large enough to cure M adjacent layers, and wherein N is at least 2 and not Greater than M. In some embodiments, the closed voxels selected for curing of each of the N selective curing layers are identified such that, in common, the subset of closed voxels selected for curing provides A nesting pattern.

In some embodiments, the methods further include performing a complete curing step after each set of N selective curing steps.

In some embodiments, a ratio RUC of the closed voxels selected to maintain uncured divided by the total number of closed voxels in the layer is greater than or equal to 0.1 and not greater than 0.9. In some embodiments, M and RUC are selected such that based on the total number of closed cells, the percentage of uncured closed cells in the three-dimensional object P% is not greater than 10%, where P%=100*RUC ^M.

In some embodiments, the closed voxels are grouped into units including a plurality of closed voxels, and each of the closed voxels in one unit is selected for curing or selected to remain uncured .

The above disclosure of the present disclosure is not intended to illustrate various embodiments of the present invention. The details of one or more embodiments of the invention are also set forth in the following description. The other features, objects, and advantages of the present invention will be apparent through the embodiments and the scope of patent application.

100‧‧‧stereolithography apparatus (SLA)/device

101‧‧‧ storey

102‧‧‧ storey

103‧‧‧ storey

104‧‧‧ storey

105‧‧‧ storey

106‧‧‧ storey

107‧‧‧ storey

108‧‧‧ storey

109‧‧‧ storey

110‧‧‧ storey

120‧‧‧Dock

122‧‧‧Light source

124‧‧‧Light controller

126‧‧‧slot

127‧‧‧ light

130‧‧‧window

140‧‧‧Object

160‧‧‧Building platform

170‧‧‧ solution

180‧‧‧Array

190‧‧‧ stereo pixels

192‧‧‧ filled stereo pixels

193‧‧‧ boundary stereo pixels

194‧‧‧ Enclosed stereo pixels

194a‧‧‧ stereo pixels

195‧‧‧ Closed stereo pixel selected for curing/cured closed stereo pixel

197‧‧‧ Selected to maintain uncured closed voxels/uncured closed voxels

199‧‧‧Open stereo pixels

199a‧‧‧Open stereo pixels

212‧‧‧Step

214‧‧‧Step

218‧‧‧Step

312‧‧‧Step

313‧‧‧Step

315‧‧‧Step

318‧‧‧Step

400‧‧‧Reverse stereolithography equipment/equipment

401‧‧‧ storey

401a‧‧‧stereo pixels

402‧‧‧Inner layer/layer

402a‧‧‧stereo pixels

402b‧‧‧ stereo pixels

403‧‧‧Inner layer

403a‧‧‧stereo pixels

404‧‧‧ storey

404a‧‧‧stereo pixels

405‧‧‧Inner layer

422‧‧‧Light source

424‧‧‧Light controller

427‧‧‧ light

430‧‧‧window

440‧‧‧Object

701‧‧‧ Nested pattern

702‧‧‧ storey

704‧‧‧ storey

711‧‧‧ completely nested patterns/patterns

712‧‧‧ storey

713‧‧‧ storey

714‧‧‧ storey

715‧‧‧ completely nested patterns/patterns

716‧‧‧ storey

717‧‧‧ storey

718‧‧‧ storey

801‧‧‧ storey

802‧‧‧ storey

803‧‧‧ storey

804‧‧‧ storey

1190‧‧‧5×5 unit/unit

1193‧‧‧Cure closed stereo pixels

1194‧‧‧Uncured closed stereo pixels

B‧‧‧ boundary stereo pixels

C‧‧‧corner/closed stereo pixel selected for curing

D‧‧‧Curing depth

E‧‧‧edge

F‧‧‧ noodles

I‧‧‧closed stereo pixels

L‧‧‧Length

O‧‧‧ open stereo pixels

T‧‧‧thickness

U‧‧‧ selected to maintain uncured closed stereo pixels

W‧‧‧Width

X‧‧‧Dimension/Direction/Axis

Y‧‧‧Dimension/Direction/Axis

Z‧‧‧Dimension/Direction

FIG. 1 is a diagram of an exemplary stereolithography apparatus (SLA).

FIG. 2A shows a cross section of a layer of a three-dimensional pixel array.

Figure 2B is the fully cured layer 105 of Figure 1 .

FIG. 2C is the layer 105 of FIG. 2B , which has boundary stereo pixels (B), closed stereo pixels (I), and open stereo pixels (O) identified according to some embodiments of the present disclosure.

FIG. 2D is the layer 105 of FIG. 2C , and all of its cured boundary voxels and closed voxels (C) selected for curing and closed voxels (U) selected to maintain uncured are identified.

FIG. 2E is the layer 105 of FIG. 2D , which is in the completion stage of a selective curing step according to some embodiments of the present disclosure.

FIG. 3 illustrates a layer-by-layer procedure of the prior art.

FIG. 4 illustrates a layer-by-layer process using selective curing according to some embodiments of the present disclosure.

FIG. 5A is a diagram of an individual stereo pixel.

FIG. 5B is a view in which the stereoscopic pixel of FIG. 5A is connected as a closed stereoscopic pixel on one side.

FIG. 6 is a diagram of a part of an exemplary stereoscopic lithography apparatus (SLA).

7A illustrates a two-layer nesting pattern according to some embodiments of the present disclosure.

7B illustrates a three-layer nesting pattern according to some embodiments of the present disclosure.

FIG. 8 illustrates a fully cured layer alternating with a selectively cured layer according to some embodiments of the present disclosure.

FIG. 9 shows a unit for selectively curing the 5 stereo pixels x 5 stereo pixels of the examples EX-15 and EX-16.

In general, the device used to implement the disclosed method is not particularly limited, and any known layer-by-layer 3D printing equipment can be used. As an example, the diagram of the reverse stereolithography apparatus (SLA) 100 is shown in FIG. 1 . The apparatus 100 includes a base 120 containing a light source 122 , a light controller 124 , and a tank 126 containing a solution 170 . In general, the composition of the solution 170 is not particularly limited, provided that it contains a curable resin. In general, any known light source can be used, for example, laser and light emitting diode (LED). The wavelength of light can be selected to match the photocuring parameters of the resin, which include, for example, the wavelength of visible light and the wavelength of ultraviolet light.

The light 127 is guided through the window 130 into the layer 101 of the solution 170 . Initially, the photocurable resin in layer 101 was uncured. The light controller responds to the data defining the characteristics of an individual layer of the 3D object and directs light only to those areas of the layer 101 in which the photocurable resin in solution 170 is to be cured. Once exposed to light 127 , the resin in layer 101 is light cured in the desired area. Layers 102 to 110 have been constructed according to this procedure and contain cured resin.

Given the range of materials, applications, and possible post-processing steps, the terms "cured" and "cured" as used herein are relative. Generally speaking, if the resin has been polymerized or cross-linked enough to achieve the desired structural integrity, it means that the resin has been "cured". For example, in a conventional procedure using photocurable resins and optional additives, a higher degree of polymerization/crosslinking may be desirable because the resin provides the mechanical properties of the final object. In colloid-forming systems, a lower degree of polymerization/crosslinking may be sufficient to keep the object in its desired shape throughout the subsequent drying and sintering steps.

During the construction process, the construction platform (also called a construction board) 160 is translated away from the solution 170 in the direction indicated by the arrow Z. In the step-by-step method, the construction platform is incrementally translated after each exposure step. In some applications, the position of the construction platform is cyclically away from and back to the solution to help provide an uncured resin layer between the lower surface of the previously cured layer and the light source 122 .

In many applications, building a program involves creating hundreds or even thousands of layers. For the purpose of illustration, the object 140 is shown as having only ten layers, which are identified as layers 101 to 110 . The layer 110 is the first layer formed and is adhered to the construction platform 160 . In some embodiments, layer 110 is directly bonded to the platform. In some embodiments, additional material may be interposed between the layer 110 and the construction platform. For example, in some embodiments, a release layer or sacrificial layer can be used to simplify the removal of the final object from the construction platform while minimizing damage.

When using 3D printing technology to create an object, the object system is defined by a plurality of cross-sectional layers that overlap each other in the Z direction corresponding to the construction axis (i.e., the axis along which the construction platform is translated) (See Figure 1 ).

Referring to FIG. 2A , the possible illumination cross-section of one layer is divided into three-dimensional pixels 190 under the array 180 , and these pixels extend in the X-axis and Y-axis to form a construction plane. As used herein, the term "voxel" refers to a three-dimensional structure defined by the thickness, width, and length of a pixel. That is, the term pixel refers to the two-dimensional cross-sectional area defined by the width and length, and the term voxel refers to the volume defined by the two-dimensional area and its thickness.

For simplicity, this layer is shown as a 10 by 10 array. The size and shape of the stereo pixel 190 are not particularly limited. Generally, what is desired is a voxel of a smaller size to achieve greater accuracy in the size of the final object. In some embodiments, the width ( W ) and length ( L ) of the voxel range independently from 40 to 70 microns, for example, 40 to 60 microns or even about 50 microns (ie, 50 +/- 5 microns) . Although square pixels are shown, other shapes including other polygons (such as rectangles) can be used.

The thickness ( T ) of the layer is aligned with the Z axis and is not particularly limited. Generally, the thickness is selected based on the depth of light penetration into the curable resin and the desired geometric accuracy of the final object. In some embodiments, the thickness of a layer ranges from 25 to 100 microns, such as 25 to 75, 40 to 60, or even about 50 microns (ie, 50 +/- 5 microns). In some embodiments, the thickness of the layer may be the same for all layers. In some embodiments, the thickness may vary between layers.

The light controller is designed to selectively illuminate the composition on a pixel-by-pixel basis. Light penetrates to provide one of the curing depths ( D ) extending in the Z direction. Generally, the curing depth depends on the light intensity, exposure time, and composition properties. Generally speaking, the depth of curing increases with increasing exposure intensity and exposure time. Compositions that exhibit greater light absorption or scattering will generally result in a lower depth of cure. The light controller can be used to tune the light source to provide the desired curing depth for a given composition. As shown in FIG. 2A, in some embodiments, the curing depth D corresponding to the thickness T, which corresponds to the thickness of a single layer of the three-dimensional pixel.

Referring to FIG. 3 , shown is a layer-by-layer method of forming an object according to one of the prior art. The individual layers are formed by, for example, photopolymerization of low molecular weight species (usually "monomers"), where a polymerization reaction is initiated by radiation activation in specific areas.

In step 212 , a composition including a polymerizable material is introduced to form a construction layer. In step 214 , the composition in each of the three-dimensional pixels corresponding to the desired object is irradiated, and the polymerizable material is cured. In step 218 , the construction platform is translated to move the now fully cured layer away from the light source and create a new construction area. Repeat steps 212 to 218 to form the final object. Therefore, in this prior art procedure, before translating each individual layer away from the light source, the complete cross-sectional area of the object corresponding to that layer is cured.

Referring to FIG. 2B , one such exemplary layer corresponding to layer 105 of FIG. 1 is shown. The filled stereo pixels 192 are filled and displayed in black to indicate that the components in these stereo pixels have been cured and will form part of the structure of the final 3D printed object. The open stereo pixel 199 is not filled and corresponds to an open area in the final part (ie, an area that does not contain cured resin). These open areas correspond to the area outside the final object and the internal voids within the object (eg, channels and cavities). Therefore, if a prior art procedure is to be used to form layer 105 of FIG. 2B , then each of the filled voxels 192 must be illuminated and the composition of their voxels will be cured in step 214 before the construction platform is translated in step 218 Thing.

Since this procedure creates discrete fully cured layers and successively has a Z-direction displacement between the layers, it is considered that the main polymer network is in the X-Y plane. Because the load must be transferred across the interface between the cured layers, this can result in poorer mechanical properties in the Z direction compared to those in the X-Y plane.

In some procedures, the nature of the Z direction is further restricted due to the relationship of the polymerization gradient. Generally, the part closest to one layer of the radiation source will receive the highest intensity radiation. Therefore, this part may have the highest degree of polymerization and the fewest remaining chemically active sites available for further polymer propagation. In contrast, due to energy absorption or scattering from the material within the layer, the part of the layer furthest away from the source of radiant energy may receive the least amount of energy. When forming a second layer adjacent to a previously cured layer, the surface of the largest reaction from the previous layer must react with the area of the new layer receiving the lowest energy dose. This can lead to unfavorable polymerization conditions, limit polymerization across adjacent layer boundaries and reduce interlayer adhesion.

As a result, the prior art layer-by-layer production method can lead to the formation of objects with significant anisotropy. Compared to the properties in the construction plane (ie, X-Y plane), the mechanical properties (such as modulus and strength) between layers in the Z direction can be much lower. For example, poor interlayer adhesion can lead to interlayer separation in the Z direction at low loads compared to the load required to deform or break an object in the X or Y direction.

These problems can be particularly important when producing parts using relatively small amounts of reactive binders to keep relatively inert particles in a shape or where the overall strength is further reduced by the presence of solvents (such as when making colloids). For example, when adhesive materials need to remove volatile components (including solvents) while maintaining shape and continuity between layers, significant weaknesses in any dimension may be unacceptable.

Therefore, although three-dimensional layer-by-layer manufacturing procedures have many advantages, such procedures frequently lead to anisotropic material properties, and challenges in improving interlayer adhesion remain.

An exemplary method of the present disclosure is shown in FIG. 4 with reference to FIGS. 2B to 2E . Again, FIG. 2B illustrates the desired final cross-section of the object corresponding to layer 105 . In the final object, the composition in filled voxels 192 will solidify, while open voxels 199 will be empty.

Referring to FIG. 2C , the solid cross-sectional area of the layer 105 is defined by first identifying the boundary stereo pixels 193 forming the object boundary. These boundary voxels are identified by the letter " B ". Next, the enclosed solid pixels 194 forming the inner solid part of the object are identified by the letter " I ". Finally, the open stereo pixels 199 are identified by the letter " O " because they etc. form the open or unfilled outer and inner parts of the object.

There are several options for distinguishing between a boundary stereo pixel and a closed stereo pixel. Referring to FIG. 5A , the stereo pixel 194a has six faces F , twelve edges E , and eight corners C. Referring to FIG. 5B , the closed voxel 194a shares at least all of its faces with the adjacent filled voxel 192 (either a boundary voxel or any other closed voxel). Since a stereo pixel has six faces, this closed stereo pixel is called "six-connected". This closed stereo pixel may also be referred to as a "face-connected" stereo pixel. In such an embodiment, a boundary stereo pixel is less than six connections, which means that a boundary stereo pixel and an open stereo pixel share at least one side thereof.

Although this definition may be suitable for some applications, in some embodiments, it may be desirable to ensure that all edges of a closed voxel are also adjacent to the filled voxel. In such embodiments, a closed voxel must share all its faces and edges with other filled voxels. Since a stereo pixel has six faces and twelve edges, this closed stereo pixel is called "eighteen-connected". This closed stereo pixel can also be called a "face and edge-connected" stereo pixel. In such embodiments, a boundary voxel is less than eighteen connections.

In some embodiments, it may be desirable to ensure that all corners of even a closed voxel are adjacent to the filled voxel. In such an embodiment, a closed voxel must share all of its faces, edges, and corners with other filled voxels. Since a stereo pixel has six faces, twelve edges, and eight corners, this closed stereo pixel is called "twenty-six-connected". This closed stereo pixel can also be called a "face, edge, and corner-connected" stereo pixel. In such an embodiment, a boundary voxel is less than twenty-six connections.

As used herein, unless the context requires otherwise, the term "enclosed voxel" includes face-connected voxel, face-to-edge voxel, and face, edge, and corner-connected voxel. The terms ``six-connected or face-connected'', ``eighteen-connected or face and edge connected'' and ``twenty-six connected or face and edge connected'' "Twenty-six-connected, or face, edge, and corner connected" is used when referring to a specific subset of closed voxels. The term "border voxel" depends on how closed voxels are defined in certain embodiments.

To determine whether a filled stereo pixel is a boundary stereo pixel or a closed stereo pixel, only the layer system in the construction area is insufficient. Instead, both the previous layer and the subsequent layer must also be considered to determine whether the desired face connection, face to edge connection, face, edge, and corner connection exists. However, for simplicity, the following description refers only to a single layer in the construction area. For this purpose, it is assumed that the filled and open voxels in the antecedent layer and subsequent layers will satisfy the desired conditions in the definition of boundary voxels and closed voxels. For example, the constructed layer and the antecedent layer and Whether subsequent layers are the same.

Referring to FIG. 2C , the surface-connected stereo pixels are regarded as closed stereo pixels. Again, assuming that each filled voxel in the construction plane is adjacent to a filled voxel in both the preceding layer and the subsequent layer, the upper and lower faces of each filled voxel will be adjacent to a Shared by filled voxels. Therefore, any stereo pixel sharing at least one side with an open stereo pixel 199 in the XY plane is a boundary stereo pixel 193 . As a result, all surfaces of the object, including both the outer surface and the inner surface, are delimited by the boundary voxels 193 . Closed voxel 194 does not share any face with an open voxel 199 . Therefore, each face of a closed voxel 194 , including its upper face and lower face, is shared with one face of either a boundary voxel 193 or another closed voxel 194 . If the closed stereo pixel has been defined as a face-to-edge connected stereo pixel, the stereo pixel 194a will be a boundary stereo pixel because it shares an edge with the open stereo pixel 199a .

As shown in FIG. 4, in step 312, introducing one polymerizable material comprising a composition layer to form a construct.

In step 313 , the composition in each boundary stereo pixel is irradiated and the polymerizable material is cured. Referring to FIG. 2D , this results in cured material in each of the boundary voxels 193 . In the method of the present disclosure, when each layer is formed, all boundary stereo pixels are cured, and only some closed stereo pixels are selectively cured. By curing all boundary stereo pixels, surface defects can be substantially reduced or eliminated. In addition, the resin in the closed solid pixel of the uncured is enclosed, and the flow of the uncured resin into the area intended to be kept open is suppressed or hindered.

2C and 2D , in the method of the present disclosure, not all of the closed stereo pixels in one layer are cured in the same step. Instead, the closed voxel 194 is divided into two subsets: the closed voxel 195 selected for curing (identified by the letter " C ") and the closed voxel 197 selected to maintain uncured (with the letter " U "Recognition).

For any given layer, the percentage of closed voxels selected for curing can range from 0 to 100%, and correspondingly, the percentage of closed voxels selected to maintain uncured can range from 100% to 0 %. However, in the method of the present disclosure, for at least some layers, the percentage of closed stereo pixels that are selected to maintain uncured is greater than 0%.

In step 315 , the composition in each closed voxel 195 selected for curing is irradiated and the polymerizable material is cured. Steps 313 and 315 can be executed simultaneously or in any order. In some embodiments, the boundary voxels and the closed voxels selected for curing are cured in the same step.

In step 318, the construction of the platform to move the partially cured layer translational (e.g., FIG. 3E) remote from the source region to create a new construct. That is, step 318 occurs before irradiating the composition in the closed voxel 197 selected to maintain uncured. In FIG. 2E , the cured boundary stereo pixel 193 is displayed with a black fill to distinguish it from the cured closed stereo pixel 195 displayed with a hash line fill. Uncured closed stereo pixels 197 are identified by the letter " U ", and open stereo pixels 199 are not filled. Repeat steps 312 to 318 to form the finished product.

If no further curing step is performed, the final object will contain a solidified boundary defined by the boundary voxels and a closed internal volume defined by the boundary voxels. Some or all of the closed voxel composition will contain uncured composition. In some embodiments, such an object may be suitable for its intended application.

However, in many applications, it is preferred to have a fully cured object. In some embodiments, the object may be post-cured after the 3D printing process is completed. For example, in some embodiments, the object may be subjected to irradiation (eg, visible light, infrared light, ultraviolet light, microwaves, electron beams, or other forms of irradiation) to cure in a 3D printing operation selected to maintain an uncured seal The composition of the stereo pixels. In some embodiments, the composition in the closed voxel selected to maintain uncured in the 3D printing operation may be thermally cured.

In some embodiments, the composition may be selected such that it is post-cured without external energy. For example, in some embodiments, the composition may be selected such that it cures on its own. In such embodiments, the 3D manufacturing process may be used to quickly form the boundary of the object and optionally the selected internal parts, while the remaining internal parts continue to solidify more slowly after the 3D manufacturing process.

However, in many applications, it may be desirable to have a fully cured object upon completion of the 3D manufacturing process. Therefore, in some embodiments, the method of the present disclosure may be modified to produce a construction region that extends across more than one construction layer.

The diagram of the reverse stereolithography apparatus 400 is shown in FIG. 6 . The device 400 includes a light source 422 and a light controller 424 . Light 427 is guided through window 430 into one or more layers of object 440 . The light controller responds to the data defining the characteristics of an individual layer of the 3D object and only directs light to those areas of the layer 401 in which the photocurable resin is to be cured. Once exposed to light 427 , the resin in layer 401 is light cured in the desired area.

The inner layer 402 to the inner layer 405 have been constructed according to the method of the present disclosure. Therefore, these layers will include open stereo pixels without resin (" O "), border stereo pixels with cured resin (" B "), closed stereo pixels with cured resin (" C "), and uncured Some combinations of closed stereo pixels (" U ") of resin. To produce a final part while minimizing or eliminating the percentage of closed stereo pixels containing uncured resin, in some embodiments, one or more of the light source, light controller, and layer thickness can be modified to provide more than a single layer One of the thickness T is the curing depth D.

As shown in FIG. 6, when the layer 401 is irradiated, the depth D is sufficient to cure the cured layer 402 and layer 403. Therefore, when the stereo pixel 401a in the layer 401 is irradiated and cured, the stereo pixel 402a and 403a are also irradiated with sufficient energy to cure the composition. As formed, the stereo pixels 402a and 403a are closed stereo pixels containing uncured resin. However, after the layer 401 is formed with the curing depth D and the stereo pixel 401a is irradiated, the resin in the stereo pixels 402a and 402b is cured and converted into a closed stereo pixel containing the cured resin.

Because the curing depth D is insufficient to cure the layer 404 , the resin in the stereo pixel 404a remains low cured or uncured. Depending on the desired end use, some degree of uncured voxels may be acceptable. However, in some embodiments, it may be desirable to minimize or eliminate the presence of uncured cells.

In some embodiments, the algorithm used to select a subset of closed stereo pixels containing uncured resin can be programmed to ensure that the total thickness T(total) of adjacent uncured stereo pixels is not greater than that shown in Equation 1. Curing depth D.

若各層的厚度係T，則可同時固化的最大層數M係

若層厚度改變，則

其中Tavg係跨固化深度D延伸的層之平均厚度。

If the thickness of each layer is T , the maximum number of layers that can be cured simultaneously is M

If the layer thickness changes, then

Where Tavg is the average thickness of the layer extending across the curing depth D.

In some embodiments, the algorithm for selecting a subset of closed voxels containing cured resin and uncured resin can be programmed to provide a completely nested pattern of closed cells containing cured resin. For example, if the curing depth is sufficient to cure the M layer, the number of repeating patterns required to achieve a completely nested pattern should be less than or equal to M For example, if the curing depth is sufficient to cure three layers, an algorithm can be used, which requires two nested patterns ( Figure 7A ) or three nested patterns ( Figure 7B ) to be cured (" C ") and uncured (“ U ”) One of the patterns of closed cells.

As shown in Figures 7A, a nested pattern 701 adjacent to layer 702 and layer 704 is composed of two complementary patterns. To achieve a nested pattern, each uncured closed cell of layer 702 is adjacent to a cured closed cell in layer 704 . In some embodiments, each cured closed cell ( C ) of layer 702 is adjacent to an uncured closed cell ( U ) in layer 704 . In this alternate nested cell pattern, when moving vertically through one of the adjacent closed cell stacks, the algorithm will alternate between cured and uncured closed cells. In some embodiments, there may be an overlap in the curing unit. In some embodiments, one curing closed cell in one layer may be adjacent to another curing cell in an adjacent layer. Therefore, alternating patterns are a subset of completely nested patterns. In some embodiments, the pattern may change across the Z direction. For example, the pattern for each even-numbered layer may be selected randomly or independently, and the pattern for each odd-numbered layer will then be a complementary pattern.

7B , the fully nested pattern 711 extends across layers 712 , 713 , and 714 . The fully nested pattern 715 also extends across three layers ( 716 , 717 , and 718 ). The algorithm is programmed to ensure that when there are three closed cells aligned across all three layers, at least one of the closed cells will be a solidified closed cell.

In some embodiments, the total Z dimension of each fully nested pattern across the object is the same. In some embodiments, fully nested patterns can be independently selected. In some embodiments, referring to the pattern 711 , a three-layer alternating pattern may be used, where there is one and only one cured closed voxel in each group of three adjacent closed voxels across the three layers. In some embodiments, for example, in pattern 715 , there may be two or even three cured closed voxels in each group of three adjacent closed voxels across three layers. In some embodiments, the pattern in one or more layers may be random, and the pattern in one or more layers may be selected to ensure that at least one of each group of three adjacent closed voxels across three layers is cured Close the voxel.

For extending a curing depth D across a larger number of layers (eg, M=4, M=5, or even greater), a completely nested pattern can be created, which requires any number of layers up to M. For example, if D is such that M=5 (ie, 5 layers can be cured simultaneously), then a nested pattern that requires 2, 3, 4, or even 5 layers can be used. The patterns selected for each group of layers may be the same or may be independently selected. For example, in some embodiments, closed voxels selected to be cured and uncured may be randomly selected, and closed voxels selected to be cured in at least one layer may be selected to ensure extension across M adjacent layers There is at least one solidified closed unit in each group of closed units.

In some embodiments, the algorithm used to select a subset of closed voxels may provide a periodic layout of fully cured layers. For example, referring to FIG. 8 , if the curing depth is sufficient to cure three layers, an algorithm that transmits one of the patterns of the cured (“ C ”) and uncured (“ U ”) closed cells can be used for the set of two layers ( 801 and 803 ) These sets are interleaved with layers ( 802 and 804 ) containing only cured voxels (ie, either of the boundary voxels or the cured closed voxels (“ C ”) as shown). The pattern of cured and uncured closed voxels in the set of layers 801 and 803 is not limited, and may include any desired pattern, including random patterns of cured and uncured closed voxels. In some embodiments, two or more fully cured layers may be interposed between the selectively cured layers.

In some embodiments, it may be desirable to avoid fully cured layers and fully nested patterns. When using random patterns of cured and uncured closed cells, the probability of exceeding one of the maximum thresholds of uncured closed cells in the final object can be controlled by selecting the ratio RUC of the uncured closed cells in each layer, where RUC is equal to The ratio of the number of closed cells that remain uncured in a layer divided by the total number of closed cells in that layer.

If M layers can be cured based on curing depth D and layer thickness (or average thickness) T , when M+1 layer is cured, if there are M continuous layers with adjacent uncured closed cells, the uncured closed The unit will remain. For each stereo pixel, the probability of occurrence Pv is: Pv=RUC ^M (4)

Each layer may contain millions of voxels, and the final object may contain thousands of such layers. As a result, the use of completely random patterns will result in some percentage of uncured voxels in the finished product. Equation (4) can be used to estimate the final percentage P% of uncured closed cells based on the total number of closed cells.

P%=100*RUC ^M (5)

Using equation (5), the ratio of uncured units (RUC) and the curing depth expressed as the number of curable layers (M) can be selected to achieve a desired percentage P% of one of the uncured closed stereo pixels. For example, in some embodiments, the percentage of uncured closed voxels in the final object is limited to no greater than 10% (eg, no greater than 5%, no greater than 1%, no greater than 0.5%, or even no greater than 0.1% ) May be as desired.

Referring to Table 1, if the threshold P% of the uncured closed voxels in the final object is selected as 1.0%, when using a RUC of 0.10 (ie, 10% of the closed cells are randomly selected to maintain uncured), The curing depth can be as low as 2 layers. However, if the RUC is increased to 0.30 (ie, 30% of the closed cells are randomly selected to remain uncured), the curing depth will have to be increased to 4 layers to achieve a P% value that is less than or equal to a threshold of 1.0%.

Equation (5) can be reconfigured to determine the maximum value of RUC that can be used based on the curing depth expressed in the number of layers M and the threshold value P, where P=P%/100.

Referring to Table 2, if the maximum percentage P% of uncured closed voxels in the final object is selected to be no greater than 1% and the curing depth is only 2 layers, the maximum value of RUC will not be greater than 0.10 (ie, at most 10% of Closed cells can be randomly selected to remain uncured). However, if the curing depth is increased to 5 layers, at most 40% of the closed cells can be randomly selected to remain uncured (ie, RUC can be as high as 0.40) while maintaining a threshold of less than 1%.

In some embodiments, the RUC is at least 0.1, for example, at least 0.2 or even at least 0.3. In some embodiments, the RUC is not greater than 0.9 (eg, is 0.8) or even not greater than 0.7. In some embodiments, the RUC is between 0.2 and 0.8, for example, between 0.3 and 0.7 or even between 0.4 and 0.6 (inclusive). In some embodiments, the RUC is the same for all layers. In some embodiments, RUC may be independently selected for each layer. In some embodiments, RUC may be selected for a group of adjacent layers such that the sum of RUC for adjacent layers is at least 1.0 (eg, at least 1.1).

Examples REF-1 and EX-1.

The precise size of the aqueous gel and the polytetrafluoroethylene (PTFE) formed in 3D are of concern because they can be further processed (dried, debonded, and sintered) to obtain The PTFE processed/processed by this method has a more complex and fine-featured dense PTFE structure. Generally, these methods use low viscosity aqueous polymer emulsion/binder solutions combined with formation techniques (including stereolithography (SLA) type 3D printing) to produce controlled structure (3D design) hydrogels.

One common technique used for SLA printing involves what is known as a "reverse vat", where (other than a standard vat) the position of the light curing radiation source is lower than a vat containing a printable liquid. In most cases, the reverse groove technique involves a series of discrete layer formations. In this case, there is a layer of lighting steps and a translation step. The translation step involves moving the construction surface and the unfinished part to a net upward position corresponding to the layer thickness. Illumination and panning alternate until the printing step is completed.

One disadvantage of the reverse groove technique for discrete layer printing is that the method involves curing one of the adhesives next to a transparent window. This means that before creating the next layer, each cured layer must be released from the window surface. Low surface energy materials, such as fluoroplastic films, often form a release surface in such window constructions, providing a lower tendency to bond to photocurable adhesives. However, even though only due to the initial suction created by the upward movement of the component during printing, there is still a force that tends to separate the printing layer in a component, which force is during the translation phase of a component Occurs when raised away from the lower window of the slot.

A second disadvantage is that the lower part of each layer is closest to the radiation source, and therefore least likely to have active sites for further cross-linking. Since the top surface of the subsequent layer in contact with this heavily cured surface of the previous layer is farthest from the radiation source, it is not advantageous to form a cross-linked bond between the layers. Likewise, as the discrete layers are cured, bridging between the layers is unlikely to cause a potential cleavage plane.

The resulting colloid is then subjected to subsequent steps, including drying, removing the binder (by burning), and sintering. All these steps may involve volume changes, which lead to stresses that may further weaken the cohesion between the layers. For this reason, increased interlayer adhesion is useful.

A 3D printable composition system containing one of polytetrafluoroethylene (PTFE) dispersions is prepared as follows. First, a modified PTFE dispersion weighing 80 grams was added to a first bottle, which was then stirred by a laboratory bottle roller. Separately weighed the first propylene-based monomer (7 g of SR 415 from Sartomer) and the second propylene-based monomer (7 g of SR 344 from Sartomer) were added to a second bottle and mixed. Subsequently, 0.288g of photoinitiator (OMNIRAD TPO-L), 0.115g of inhibitor (BHT from Sigma Aldrich), and 0.058g of optical brightener (MAYZO OB-M1) were added to the second bottle , And continue to agitate the contents on the laboratory roller machine for at least 30 minutes. Finally, 20g of water was added and further mixed on a laboratory roller bottler to form a binder mixture. Once completely mixed, the binder mixture was slowly added to the dispersion, and the resulting 3D-printable composition was further stirred on the laboratory roller bottler for the entire time before use.

The part design is a sheet of 40mm by 20mm. The conditions shown in Table 3 below use a RAPIDSHAPE HA40 SLA printer (Rapidshape GmbH, Heimsheim, Germany) to print samples layer by layer to a thickness of 1.5 mm. The object system is a solid sheet, delimited on the top and bottom by a fully cured layer, where each inner layer is the same and consists of a boundary surrounding the inside of a solid rectangle.

Reference Example REF-1 was prepared by curing the whole of each layer in each step. That is to say, when printing a separate layer, all the three-dimensional pixels (that is, both the boundary three-dimensional pixels and all the closed three-dimensional pixels) are irradiated to cure the resin and form a hydrogel.

Example EX-1 was prepared using the method of the present disclosure. The top layer and the bottom layer are fully cured because they etc. consist only of boundary cells forming the top and bottom surfaces of the object. When the inner layer is formed, all boundary stereo pixels are irradiated to cure the resin. The closed stereo pixels are divided into an array of 1mm by 1mm cells. The closed stereo pixels in these internal layers are illuminated with a checkerboard pattern. The units selected for irradiation are alternated in alternating layers so that the units are illuminated in alternating steps. Since the exposure energy is selected to ensure a curing depth of at least two layers (ie, at least 100 microns), all closed stereo pixels are exposed to sufficient energy to cure the resin and form a hydrogel.

After each printing, the hydrogel samples were rinsed in deionized water, and the residual surface liquid was blown off with a lightly pressurized nitrogen flow, and the samples were post-cured under ultraviolet light for 30 seconds (DYMAX light curing system model 2000 Flood, which has a 400-watt EC power supply). These samples were then solvent exchanged with ethanol by immersing the printed hydrogel in two consecutive soaks in 200 alcohol ethanol for a minimum of one day each. The preparation of supercritical CO2 extraction is performed by transferring the solvent-exchanged hydrogel from the second ethanol bath to the metal support. To minimize the evaporative drying of ethanol, the samples were periodically wetted with ethanol during the transfer. When loading the carrier, place it in an extraction chamber.

The supercritical extraction system was performed using a 10-liter laboratory scale supercritical fluid extractor unit, which was designed and obtained from Thar Process, Inc., Pittsburgh, PA, USA. The PTFE-based colloid is installed in a stainless steel frame. After sealing the lid of the extractor vessel in place, the liquid carbon dioxide was pumped through a heat exchanger by a cooling piston pump (setpoint: -8.0°C) to heat CO2 to 50°C and enter the 10-L extractor In the container, until an internal pressure of 13.3 MPa is reached. Under these conditions, carbon dioxide is supercritical. Once the operating conditions of the extractor at 13.3 MPa and 50°C are met, the pressure in the extractor vessel is adjusted as soon as the heated needle valve. CO2 and dissolved ethanol flow downstream into a 5-L cyclone vessel maintained at room temperature and a pressure of less than 5.5 MPa, where the extracted ethanol and gas-phase CO2 are separated and collected during the entire extraction cycle. From the time the operating conditions are reached, supercritical carbon dioxide (scCO2) is continuously pumped through the 10-L extractor vessel for 3 hours. After the three-hour extraction cycle, the extractor vessel was vented to the cyclone within one hour, from 13.3 MPa to atmospheric pressure at 50°C, after which the cover was opened and the stainless steel rack containing the dried aerogel was removed.

在步驟9之後，開啟烘箱並允許樣本冷卻至室溫。 The dried aerogel is placed on a layer of ceramic (La Zr Al oxide) beads in an aluminum pan for burning and sintering in a programmable air circulation oven of Despatch Industries model RAF 1-42-2E , The oven is programmed according to the following program:

After step 9, turn on the oven and allow the sample to cool to room temperature.

Tensile samples were prepared and tested according to ASTM D1708. The test was conducted at an elongation rate of 12.7 mm per minute. Record the tensile stress at break and elongation at break of each sample, and report the average and standard deviation as follows.

Examples REF-2 and EX-2 to EX-16.

Preparation of a 3D printing, UV-curable acrylate composition. The composition contains 45 wt.% urethane elastomer (EXOTHANE 10, available from Esstech, Inc.), 26 wt.% 2-phenoxyethyl methacrylate, 18 wt.% methacrylic acid 2-ethylhexyl ester, and 11 wt.% of isobornyl methacrylate to produce 100 parts by weight of resin. The composition further includes 0.5 parts of photoinitiator (TPO, available from IGM Resins USA Inc.) and 0.025 phr of inhibitor (BHT, (2,6- Di(tertiary butyl)-4-cresol), product code #34750, available from Sigma-Aldrich, St Louis, MO, USA), and 0.025 phr of naphthalimide acrylate.

Dog bone samples are designed according to ASTM D-638 Type V dimensions. The design is modeled in a 3D computer-aided drafting program (from Dessault Systemes SOLIDWORKS Corp.) and converted into .STL format for import into the software program to convert the solid model into individual layers (NETFABB software from Source Graphics) . The dog bone samples are designed so that the layers are stacked with their X-Y plane perpendicular to the length direction of the dog bone samples.

Prepare a .TGZ file containing one link file for each layer pair. One file is a .PNG image, which defines a two-dimensional image mask for the layer. The second file is an .XML file, which defines the corresponding parameter set for the layer. These files are customized with a scripting language (Python Software Foundation). Parameter customization is processed through the comparison and substitution of the regular expressions of individual parameters. The final values of the modified parameters are listed in Table 5.

Sixteen print profiles were prepared, including a fully cured control group REF-2. For each sample, the layer-by-layer images are loaded into memory to generate a three-dimensional matrix of construction. Based on a network of 26 connected pixels, the boundary stereo pixels in each layer are identified. This means that closed voxels are connected by 26 (ie, a closed voxel is connected to the face, edge, and corner to adjacent filled voxels), and the boundary voxels are less than 26 connected (that is, with adjacent to (Any voxel whose open voxel is one of its face, edge, or corner is identified as a boundary voxel). This analysis is performed by confirming the state of the voxels in the constructed layer and in the preceding layer and the successive layers.

When processing a layer, all boundary stereo pixels are irradiated to cure the resin. In the case of REF-2, all closed stereo pixels are also irradiated to cure the resin. For each of Examples EX-2 to EX-16, a pattern was applied to the closed pixels, as summarized in Table 6.

In Table 6, the cell size refers to the size of the stereo pixels grouped into a cell and processed together when creating the pattern. For example, a 3×3 cell size means that each cell forms a group of closed stereo pixels in a 3×3 array. (For example, EX-4.) RUC is selected to maintain the ratio of uncured units to the total number of closed units. "Pattern" determines how to use the RUC value. In a 50% checkerboard pattern, alternating cells are selected for irradiation to form a two-dimensional checkerboard array of cured and uncured closed cells. EX-7 has alternating cells, where each cell is a closed stereo pixel, while EX-8 has alternating cells, where each cell is a 3×3 array of closed stereo pixels.

In random patterns, the algorithm uses the RUC value as a probability applied to each cell. Therefore, for a 50% RUC random pattern (EX-2 to EX-10), the probability that each unit is selected to remain uncured is 50%. Therefore, it is possible to make the two cured or uncured closed cells closer to each other, but the average number of uncured cells should be maintained at approximately 50% across an entire layer. For a 40% RUC random pattern (EX-11 and EX-12), the probability that each unit is selected to remain uncured is 40%.

In some embodiments, the pattern is selected to repeat. In Table 6, "alternating" is associated with checkerboard patterns (EX-7 and EX-8). This means alternating the same pattern so that each even layer has the same checkerboard pattern and each odd layer has the same complementary checkerboard pattern. The term "2x alternating" means that each pair of adjacent layers has a complementary pattern that results in a nested pattern. However, these patterns change with the Z direction of the object. Therefore, one layer has a first random pattern, and its adjacent layer has a reverse pattern of the pattern. However, the next layer has a new randomly selected pattern, and its adjacent layer has a reverse pattern of that pattern. As a result, if the RUC of one layer is 50%, the RUC of the adjacent layer is the inverse of that, and the adjacent layer also has 50% RUC (EX-1 to EX-5). If the RUC of one layer is 40%, the RUC of the adjacent layer is the inverse of that, and the adjacent layer has 60% RUC (EX-13 and EX-14).

Examples EX-15 and EX-16 are based on a pattern designed to provide a larger uncured closed cell length across adjacent layers. As shown in FIG. 9, line base pattern 5 × 5 unit 1190, having thirteen perspective uncured closed closed twelve pixels 1194 and cured voxel 1193, RUC-based stars of 52%. Unit 1190 is placed in a column along an axis, and is offset by a stereo pixel in an adjacent column in the same plane. This pattern is repeated for each layer, but the entire pattern is shifted downward by one row of voxels (EX-15) between layers or by two rows of voxels (EX-16) between layers.

Ten samples were prepared for each pattern by printing a UV-curable acrylate composition to form a dog bone shape. Wash the printed samples with isopropyl alcohol. The washed samples were post-cured in a UV chamber for three hours and dried in a vacuum oven at 100°C for 18 hours.

According to ATSM test method D638, INSIGHTS MTS with a load cell of 5 kN was used to measure its tensile strength at break, modulus, and elongation at break at a rate of 10 mm/min. The dog bone samples were prepared so that the layers were stacked with their X-Y plane perpendicular to the length direction of the dog bone samples. As a result, the load applied in the tensile test is perpendicular to the layer, that is, parallel to the thickness of the layer, so that the load must be transferred across adjacent layers. Use digital image correlation to measure strain and strain distribution in a sample. The tensile strength, modulus, and elongation at break were determined according to ASTM D638-10. The test was repeated ten times, and the average value and standard deviation were summarized in Table 7, Table 8, and Table 9.

The ratio of the tensile strength after selective curing to the tensile strength of the control sample (REF-2) is shown in Table 8. The tensile strength at failure of all the selectively cured samples is higher than that of the control samples. This indicates that the interlayer strength is greater.

As shown in Table 9, the modulus of all the selectively cured samples is also higher compared to the control group. Generally, there is a trade-off between modulus and elongation at break. As a result, selective curing can produce samples with higher or lower modulus and elongation at break compared to samples prepared from standard fully cured layers, while retaining the benefits of improved tensile strength at break.

Various modifications and changes in the present invention will be obvious to those having ordinary knowledge in the technical field, and do not depart from the scope of the present invention.

400‧‧‧Reverse stereolithography equipment/equipment

401‧‧‧ storey

401a‧‧‧stereo pixels

402‧‧‧Inner layer/layer

402a‧‧‧stereo pixels

403‧‧‧Inner layer

403a‧‧‧stereo pixels

404‧‧‧ storey

404a‧‧‧stereo pixels

405‧‧‧Inner layer

422‧‧‧Light source

424‧‧‧Light controller

427‧‧‧ light

430‧‧‧window

440‧‧‧Object

D‧‧‧Curing depth

T‧‧‧thickness

Z‧‧‧Dimension/Direction

Claims (24)

A layer-by-layer method for forming a three-dimensional object from a composition including a polymerizable material, wherein the three-dimensional object includes internal layers, the internal layers include a stereo pixel array, and the array includes boundary stereo pixels, wherein the boundary stereo The pixels include stereo pixels less than six connected, and closed stereo pixels corresponding to a cross-sectional area of the three-dimensional object delimited by the boundary stereo pixels, wherein the closed stereo pixels include closed stereo selected for curing Pixels and closed stereo pixels selected to maintain uncured, and each stereo pixel in one layer has a width W and length L measured along an orthogonal axis in the plane of the layer, and each layer has a perpendicular to the A thickness T measured by the layer. The method includes a selective curing step. The step includes: (i) providing an uncured layer of the composition in a construction area; (ii) creating a selection by Curable layer a. curing the polymerizable material in the boundary stereo pixels; and b. curing the polymerizable material in the closed stereo pixels selected for curing, wherein the closed for the curing is selected The stereo pixels include less than all of the closed stereo pixels; and (iii) the selective curing layer is translated to recreate the construction area; wherein curing the polymerizable material includes irradiating the composition in the construction area to a curing depth D , Where D is greater than or equal to T. The method of claim 1, further comprising repeating the selective curing step N times to form N consecutive selective curing layers, wherein D is large enough to cure M adjacent layers, and wherein N is at least 2 and not greater than M. The method of claim 2, wherein the closed voxels selected for curing of each of the N selective curing layers are identified such that, in common, the closed voxel pixels selected for curing The set provides a nesting pattern. The method of claim 2, further comprising performing a complete curing step after each set of N selective curing steps, the complete curing step comprising: (iv) providing an uncured layer of the composition in the construction area; (v) create a fully cured layer by c. curing the polymerizable material in the boundary stereo pixels; and d. curing the polymerizable material in all the closed stereo pixels; and (vi) translating the complete The layer is cured to create a new construction area; where N is not greater than M-1. The method of claim 2, wherein the ratio of the closed voxels selected to maintain uncured divided by the total number of closed voxels in the layer (RUC) is greater than or equal to 0.1 and not greater than 0.9. The method of claim 5, wherein RUC is greater than or equal to 0.4 and not greater than 0.6. The method of claim 2, wherein M and the ratio of the closed voxels selected to maintain uncured divided by the total number of closed voxels in the layer (RUC) is selected such that based on the total number of closed cells, The percentage P% of uncured closed cells in the three-dimensional object is not more than 10%, where P%=100*RUC ^M. As in the method of claim 7, where P% is not greater than 1%. The method of claim 1, wherein the closed voxels are grouped into units including a plurality of closed voxels, and each of the closed voxels in a unit is selected for curing or selected to maintain Not cured. The method of claim 9, wherein each unit is a v by v stereo pixel array, where v is an integer. As in the method of claim 10, where v is not greater than 10. The method of claim 1, wherein the boundary stereo pixels include less than eighteen connected stereo pixels. The method of claim 12, wherein the boundary stereo pixels include less than twenty-six connected stereo pixels. The method of any one of claims 1 to 13, wherein the polymerizable material comprises acrylate, methacrylate, or a combination thereof. The method according to any one of claims 1 to 13, wherein the composition comprises polytetrafluoroethylene. The method according to any one of claims 1 to 13, wherein the composition includes a solvent, and the three-dimensional object includes a colloid. The method of any one of claims 1 to 13, further comprising post-curing the three-dimensional object. A method for forming a three-dimensional object from a composition including a polymerizable material, wherein the three-dimensional object includes a plurality of inner layers, wherein each inner layer includes a three-dimensional pixel array, and the array includes a boundary three-dimensional object corresponding to a boundary of the object Pixels and closed stereo pixels corresponding to a cross-sectional area of the three-dimensional object demarcated by the boundary stereo pixels, the method includes: introducing the composition between a construction platform and a window for each internal layer Build a region; perform a curing step, which includes a. for each boundary stereo pixel of the layer, irradiating the composition to cure the polymerizable material in the boundary stereo pixel; b. for each closed stereo pixel of the layer Any one of the following i. irradiate the composition so that the polymerizable material in the closed stereo pixel is cured, or ii. not irradiate the composition so that the polymerizable material in the closed stereo pixel is substantially uncured; And translating the construction platform and the layer away from the window to create a new construction area, wherein for at least one inner layer, the composition in at least one closed voxel has not been translated from the construction platform and the layer away from the window After curing. The method of claim 18, wherein the three-dimensional object further includes a first outer layer and a second outer layer, wherein each outer layer includes a stereo pixel array, the array includes boundary stereo pixels corresponding to the boundary of the object and corresponding In a closed stereo pixel of a cross-sectional area of the three-dimensional object delimited by the boundary stereo pixels, the method includes: for the first outer layer, performing the curing on the first inner layer for one of the plurality of inner layers Before the step, the composition is introduced into a construction area and a curing step is performed. The curing step includes: a. For each boundary stereo pixel of the first outer layer, the composition is irradiated so that the Polymerized material curing; b. for each closed stereo pixel of the first outer layer, irradiating the composition to cure the polymerizable material in the closed stereo pixel; and for the second outer layer, for the plurality of inner layers After performing the curing step in one of the last inner layers, the composition is introduced into a construction area and a curing step is performed. The curing step includes: c. For each boundary stereo pixel of the second outer layer, irradiating the composition such that Curing the polymerizable material in the boundary stereo pixel; and d. for each closed stereo pixel of the second outer layer, irradiating the composition to cure the polymerizable material in the closed stereo pixel. A three-dimensional object produced by a method as in any one of request items 1 to 13, request item 18, or request item 19. The three-dimensional object of claim 20, wherein the polymerizable material comprises acrylate, methacrylate, or a combination thereof. The three-dimensional object of claim 20, wherein the composition comprises polytetrafluoroethylene. The three-dimensional object of claim 20, wherein the composition includes a solvent, and the three-dimensional object includes a colloid. The three-dimensional object according to claim 20, wherein the three-dimensional object is post-cured.

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