Leading Hollow Fiber Membrane Spinning Machine and Spinneret Manufacturer - Trustech

Polymer Fiber Spinning, Dual Layer Spinning Spinneret 1

Polymer Fiber Spinning, Dual Layer Spinning Spinneret 2

Polymer Fiber Spinning, Dual Layer Spinning Spinneret

Dual layer dope spinneret spinneret, also called a composite membrane spinneret, is a key forming component used in membrane separation/filtration manufacturing. In a single co-extrusion step, it laminates two or more functional dopes into a prescribed layered architecture and shapes them through micron-precision orifices or slots into a layer-by-layer structured membrane. Its core role is to stably and controllably stack and form multiple fluid streams within a microscale flow space.

Inquiry

Write a Review

Typical application scenarios

Polymer Fiber Spinning, Dual Layer Spinning Spinneret 3 Membrane formation for separation, commonly referred to as co-extruded composite membrane or cast film spinnerets.

Polymer Fiber Spinning, Dual Layer Spinning Spinneret 4 Hollow fiber membranes, flat sheet membranes, nanofiltration/ RO precursor membranes, and systems such as cellulose acetate, polysulfone, and PVDF.

Polymer Fiber Spinning, Dual Layer Spinning Spinneret 5 Two or multi-layer co-extrusion to create a skin /selective layer, functional layers, and a support layer.

00Trustech hollow fiber spinneret 16hole spinning (2)

Trustech hollow fiber spinneret

Trustech Spinneret Key Design Elements Trustech

These parameters are fundamental to spinneret design and directly determine the membrane's final performance

Parameter	Description	Influence on membrane performance
Flow channel (R)	The runner for transporting, buffering, and distributing the dope and bore fluids.	Different structures should be optimized according to material properties, viscosity, spinneret orifice size, and hole quantities to achieve optimal spinning performance.
Annular gap width (d)	The gap (thickness) of the dope flow channel.	It primarily determines the hollow fiber wall thickness. Narrower gaps yield thinner walls and lower mass-transfer resistance, but may reduce mechanical strength.
Bore tube outer diameter (d₁)	The outer diameter of the central tube forming the inner wall of the annular gap.	Together with the outer sleeve inner diameter, it defines the annular gap width.
Outer sleeve inner diameter (d₂)	The inner diameter of the spinneret outer sleeve forming the outer wall of the annular gap.	Together with the bore tube outer diameter, it defines the annular gap width and the fiber outer diameter.
Central tube inner diameter (d₃)	The diameter of the bore fluid channel.	It primarily determines the fiber inner diameter. The inner diameter affects membrane module packing density and the pressure drop of fluid inside the fiber.
Central tube inner diameter (d₃)	The diameter of the bore fluid channel.
Length-to-gap ratio (L/d)	The ratio of the flow channel length (L) to the annular gap width (d).	It affects spinning stability. Designing an appropriate L/d according to material properties and process conditions helps stabilize flow and eliminate entry effects, resulting in more uniform extruded fibers membrane.
Concentricity	The coaxial alignment among the dope layer inner diameter at the spinneret outlet and the bore tube inner and outer diameters.	It affects wall-thickness uniformity and bubble point pressure.
Concentricity
Extrusion face geometry	The foremost geometry of the spinneret, such as flat or micro-tapered.	It influences draw-down and deformation after extrusion, especially important for the air-gap segment in dry-wet spinning.

Trustech hollow fiber spinneret 16hole spinning

The Advantages of Trustech Dual Layer Spinneret Trustech

Polymer Fiber Spinning, Dual Layer Spinning Spinneret 9 One shot multi-layer co-extrusion: A single extrusion precisely stacks a dense selective layer over a porous support layer, with controllable layer thickness and interfaces. No downstream lamination or coating is required, simplifying the process and improving layer stability.

Polymer Fiber Spinning, Dual Layer Spinning Spinneret 10 On demand material configuration for cost reduction: Use low cost, high volume resin for the support layer and only a small amount of high performance, higher cost material for the functional layer. Raw material costs drop by 30–50% while achieving high separation accuracy, high flux, and anti-fouling performance.

Polymer Fiber Spinning, Dual Layer Spinning Spinneret 11 Robust interfacial fusion without delamination: Leveraging 0.003 mm concentricity machining precision and refined flow path design, the dope streams form clear, stably fused interfaces within micron-scale channels, ensuring strong interlayer bonding with no delamination risk and superior long-term structural and performance stability.

Product Parameters

Brand	Trustech	Application	Dual layer
Material	SUS304, SUS630, SUS316L	Holes/Pack	1 or 4
Dope inlet Thread	G1/8, BSP1/8, NPT1/8	Minimum membrane OD	1.3mm
Bore liquid inlet thread	G1/8, BSP1/8, NPT1/8	Customize thread	Yes
Precision	±0.002mm	Concentricity	0.003mm
Design	Conventional design	Connections	Standard
Viscosity application	1000-300000cp	Roughness	Ra0.2-0.8
Solvent	DMAC, DMF, NMP	Temperature	150℃

Suitable Materials

PVDF (Polyvinylidene Fluoride), CA (cellulose acetate), PVC (Polyvinyl chloride), PES (Polyethersulfone), PSF/PSU (Polysulfone), PA (Nylon, Polyamide), PAN (polyacrylonitrile)

Structural Features

Dual layer dope spinneret is challenging to manufacture, requires high concentricity, and, when necessary, must withstand high temperatures and solvents such as DMAC and NMP.

We offer double material liquid hollow fiber membrane spinnerets used for producing composite membranes. The concentricity of these spinnerets are 0.003mm. The composite film covers a dense separation layer on the porous base film. The support layer and the separation layer use different materials, which makes it easy to obtain a separation membrane with a high separation function, high permeation flux, excellent resistance to pollution and an outstanding strength. We can also make films for specific functions using this process.

Conventional design

FCT design

Common Specifications

No.	General Specification	Application	Design Type	Type
1	1.6/1.3/1.1/0.7/0.4	Dual layer	Conventional design	Single-aperture/ Multi-aperture
2	1.7/1.3/1.0/0.6/0.3	Dual layer	Conventional design	Single-aperture/ Multi-aperture
3	1.8/1.2/0.9/0.7/0.4	Dual layer	Conventional design	Single-aperture/ Multi-aperture
4	1.8/1.4/1.1/0.7/0.4	Dual layer	Conventional design	Single-aperture/ Multi-aperture
5	1.9/1.6/1.3/0.7/0.4	Dual layer	Conventional design	Single-aperture/ Multi-aperture
6	1.94/1.3/0.9/0.7/0.3	Dual layer	Conventional design	Single-aperture/ Multi-aperture
7	2.1/1.6/1.3/0.8/0.5	Dual layer	Conventional design	Single-aperture/ Multi-aperture
8	2.2/1.9/1.6/1.1/0.8	Dual layer	Conventional design	Single-aperture/ Multi-aperture

Customer Membrane Examples