Meltblown Structures Formed by a Robotic and Meltblowing Integrated System: Impact of Process Parameters on Fiber Orientation and Diameter Distribution

Abstract

In a previous publication, we described a novel system that forms three-dimensional (3D) structures on 3D molds and two-dimensional (2D) structures on a rotating drum through proper integration of a laboratory scale meltblown unit with a small die and a six-axis robot. In this paper, we investigate the impact of take-up speed. die-to-collector distance (DCD). polymer throughput rate. and attenuating air pressure on the fiber orientation and diameter distribution of 2D structures formed by the system. We introduce a new parameter, the fiber stream approach angle, which can be precisely controlled by the robot, and discuss its impact on the meltblown structure. In the experimental range studied, fiber orientation and diameter distribution are significantly impacted by the parameters. Among these parameters. the fiber stream approach angle shows the highest effect on fiber orientation distribution.Due to their unique microstructure. meltblown nonwoven webs are characterized by lightweight, high-surface area. fine porosity, softness, and high absorbency. which make them good components for protective garments and filtration applications. Currently, the meltblowing technology is used to manufacture tiberwebs in sheet form. but it is impossible to form garments from sheets without joints and/or seams. These seams or joints represent weak links in a protective clothing system, and such links are potential hazards for users of protective clothing. This drawback has prompted us to undertake research with the objective of producing 3D molded seamless meltblown structures by developing a novel robotic fiber assembly and control system (RFACS). In an earlier paper [4], we provided the RFACS description and capabilities along with a study about controlling the basis weight uniformity of 3D molded ti.berwebs.While the main objective of RFACS 1!~ to produce 3D meltblown webs of varying curvatures. a study of the structures of 2D meltblown webs is still providing important data on structures produced by RFACS. since the webs are formed with a small die size compared to the drum (collecting surface) size. Further. manipulating the die by the robot provides precise control of the die orientation relative to the collector surface. Thus. new parameters that may control the structures and properties of meltblown fiberwebs can be studied.It is well known that the fiber diameter and orientation of nonwoven structures govern their properties. such as softness, wicking/absorption. pore shape. pore size. and filtration efficiency. In this paper. we examine the influence of process parameters on fiber orientation (represented by the orientation distribution function. ODF) and fiber diameter distribution of 2D fiberwebs produced by RFACS using a drum as a collector. We also examined a new parameter, the fiber stream approach angle. which can be precisely controlled by the robot manipulator. ExperimentalMeltblown nonwoven samples were produced from polypropylene (PP) resin with a nominal melt flow rate (MFR) of 1200 using RFACS. The processi...

Meltblown Structures Formed by a Robotic and Meltblowing Integrated System: Impact of Process Parameters on Pore Size

“…Our results of fiber diameter as impacted by the DCD agree with previous studies [ 14,16,17]. Fiber orientation in the MD increases when the DCD increases from 7 to 14 cm and decreases when the DCD increases from 14 to 31 cm [8]. The results of the anisotropy parameter, which is estimated from fiber orientation distribution or FOD [ 10], of Table I support this fact.…”

“…basis weight, and cumulative frequency of pore sizes of meltblown fabrics processed with various polymer throughput levels. Similar to the influence of throughput on the diameter distribution of fibers in the web [8], the average diameter of the pore size in the web decreases with decreased throughput of the polymer in the meltblowing system. Decreased fiber diameter due to decreased throughput decreases (Table IV) the pore size of the fabric, while decreased basis weight should increase the pore diameter.…”

“…The basis weights of the fabrics are reported in Figures 7 and 11. The meltblowing equipment specifications were as previously reported [8].…”

“…If these webs are to be used as filtration materials or as membranes in protective gear, it is essential to characterize the diameter distribution, orientation distribution, basis weight, and pore size and distribution. We reported and discussed the influence of process parameters on fiber orientation distribution and fiber diameter in an earlier publication [8] and investigated the control of basis weight uniformity of meltblown fiber webs formed on a 3D mold in another earlier work [7]. Pore size and shape variation data for simulated web structures produced under different conditions from image analysis have been reported in the literature [9,13,19].…”

Developments in 3D nonwovens

“…The varying curvature of the 3D shape further adds to the complexity. The final product property will be affected by a range of parameters including the choice of polymer, the various flow conditions, the fibre density distribution and the fibre orientation distribution (Farer et al, 2002(Farer et al, , 2003Velu et al, 2004). This technique combines fibre production and 3D product manufacture into a single process, and the fibre product is composed of very fine fibres.…”