The document introduces digital light processing (DLP) 3D printing technology for producing fabrics using a polyurethane acrylate photopolymer. First, a knitted textile structure was modeled and the effect of acrylate oligomer concentration was evaluated. The optimal printing conditions of curing time and layer thickness were determined. Lastly, the DLP printed textile was compared to one printed with fused deposition modeling, with DLP found to provide better flexibility, strength and wrinkle recovery due to the photopolymer material.

1. Welcome to the Presentation of Digital
Printing Technologies
• Development of fabrics
by digital light
processing three-
dimensional printing
technology and using a
polyurethane acrylate
photopolymer
Literature name
Presented by:
Sudipta Das
ID: 1915226017

2. Main theme of this literature:
To produce fabrics by the
digital light processing (DLP)
(3D) printing technology and
using a polyurethane acrylate
photopolymer as the printing
material.
Evaluating The DLP 3D
printing conditions, such as
the curing time and layer
thickness
Considering the physical
properties, such as the tensile
strength, elongation, and
crease recovery of the 3D
printed material.

3. • FDM(fused deposition
modeling)
The FDM has low-cost
equipment, but the flexibility
of the printed material is
very lowing to the
characteristics of the used
materials.
• SLS (Selective Laser sintering)
The SLS 3D printing
technology can provide
excellent strength and
a precise product;
however, the
equipment cost is very
high.
• DLP(Digital Light Processing)
We introduce the digital light
processing (DLP) 3D
printing technology, which
has the advantages of low
equipment cost and a high
production rate. Moreover, it
can control the physical
properties of the 3DP
material.
However, there are two main limitations in the application of 3D printed materials (hereinafter, 3DP materials as fabrics.)
1. Lack of the physical properties of 3DP material. There are no researches to evaluate the physical properties, such as strength
and elongation of 3DP material and to analyze the results. Most of the related researches have pre sented the appearance of
printed materials.
2. The second limitation is the price of the 3D printing equipment.

4. Firstly
• the structure of 3D textile material was modeled using knit structures to provide
the required flexibility and strength as fabrics
Secondly
• the effect of the acrylic oligomer concentration was evaluated considering the
physical properties of the 3DP textile
Thirdly
• the DLP 3D printing conditions were optimized by evaluating the curing time and
layer thickness.
Lastly
• the 3DP textile was compared with those printed using a FDM 3D printer, which
has a lower price than other printers and is widely used in the fashion area
Working procedure of this literature:

5. Materials and Methods
DLP
A polyurethane acrylate
photopolymer was used
in the DLP 3D printing
technology (hereinafter,
DLP)
FDM
acrylonitrile butadiene
styrene (ABS) copolymer
filaments were used in the
FDM technology
(hereinafter, FDM).
Rhino (Rhinoceros 3D 6.0, Robert
McNeel & Associates, USA)
software was used for the textile
structure modeling. To obtain the
basic printing condi- tions, we
modeled the textile with connected
fine loops and smooth 3D surfaces
by applying the knit stiches structure.

6. Printing technologies
.
The configuration of the DLP
printer is the preset that the
printer has as it was
manufactured, as follows: an UV
light-emitting diode (LED) (405
nm) as the light source; printing
speed of 6.2s/100mm.
The configuration of the FDM
printer is the preset that the printer
has as it was manufactured, as
follows: infill and nozzle speed of
200 mm, 25% and 80 mm/s,
respectively; the extruder and bed
temperatures were 210 C and 60􏰀
C, respectively

7. Result and Discussion
Effects of the concentration of acrylate oligomers:
As shown in Figure 3, with 10% of acrylate
oligomer concentration in the photopolymer, the
sample exhibited the highest tensile strength
and elonga- tion, which gradually decreased at
higher concentrations. The measurement results
showed a trend of increase in crease recovery
with the acrylate concentration. The
measurement results showed a trend of increase
in crease recovery with the acrylate
concentration.
Therefore, the appropriate printing material for
the manufacture of the 3DP textile based on the
measured tensile strength, elongation, and
crease recovery is sample A, whose
concentration of acrylate oligomer is 10%.

8. Result and Discussion
Effects of curing time: As photopolymers are polymerized and hardened by
the light energy, the curing time is an important
parameter, which controls the properties of the prints.
Figure 4 shows the measured tensile strength,
elongation, and crease recovery of the 3DP textile
according to the normal layer curing time (8, 10, 12,
14, 16, 18, and 20 s). A longer curing time led to a
higher tensile strength, as when the time of exposure to
light energy (external stimulus) was increased, the
termination reaction of free radical polymerization was
delayed, which increased the degree of molding into a
solid. The elongation was the lowest at the curing time
of 8s. All other cases exhibited similar values. The
material was harder at 16 s (or after a longer time) and
a fracture occurred during the experiment, thus
disabling the measurement of the crease recovery.
Therefore, the tensile strength, elongation, and crease
recovery show that the appropriate curing time for the
printing material (sample A) used for the production of
the 3DP textiles is 14 s

9. Result and Discussion
Effects of the layer thickness: For the textile printed with a layer thickness
smaller than 50 micrometer, its properties
cannot be measured as they failed even under a
small pressure. Furthermore, for the textile
printed with a layer thickness larger than
200micrometer, the properties could not be
measured as they were easily weakened and
broken by the pressure in the direction of the
fault for the same curing time.
Therefore, considering the surface morphology,
the appropriate layer thickness of the printing
material for the manufacturing of 3DP textile
was 100micrometer.
Moreover, when the layer thickness was larger
than 200micrometer, the resolution and
durability were decreased (Figures 5(e) and (f))

10. Comparison on DLP & FDM printing Technologies
DLP FDM
Polyurethane acrylate photopolymer. ABS
Printing time 9 min 37 s 204 min 31 s
Cost US$0.08 US$0.31
higher printing resolution and more
irregular surfaces,
The 3DP textile by FDM exhibited a
relatively lower printing resolution and
more irregular surfaces.
DLP has flexible natural drape
characteristics when creating loops.
Drape characteristics is not good.
The 3DP textile by DLP presented
good flexibility, stiffness, and crease
recovery. The hardness of the
polyurethane acrylate photopolymer
can be controlled by oligomer contents
ABS for FDM has higher stiffness than
that of the polyurethane acrylate
photopolymer. Thus, for the 3DP
textile for FDM with ABS, modeling
with other structures such as chain mail
or different printing material has to be
applied to get better tensile strength,
elongation.

11. Epilogue:
After introducing this DLP 3D printing, we have come on some decisions of physical properties of tensile strength, elongation, crease
recovery, and appearance. As the results, the optimal printing conditions were derived as follows: concentration of acrylate oligomer
in the photopolymer: 10% ; curing time per layer: 14 s; and layer thickness: 100 mm. The modeling was designed for DLP with a
polyurethane acrylate photopolymer; the 3DP textile by DLP presented good tensile strength, elongation, and wrinkle recovery. When
the same modeling design was transmitted to DLP and FDM printing technologies, the appearance and properties of the 3DP textile
were different because of the disparate printing mechanisms of the hardening photopolymer by lighting in DLP and fused deposition
in FDM.
This study has advantages of introducing a new type of 3D printing technology, DLP and printing material, and polyurethane acrylate
photopolymer in the fashion area with reduced cost of equipment and material and a better production rate.
https://journals.sagepub.com/doi/abs/10.1177/0040517519881
821
Future Suggestions is for working on 4D printing.
Thank You