Multi-layer Coextrusion Film Material for Single Use BioProcess Bags

The Characteristics of Multi layer Coextrusion Film Material for Single Use Bioprocess Bags：

1) Has good gas barrier properties, water resistance, strength, bending resistance, and puncture resistance, with a tensile strength of up to 20MPa, an oxygen permeability of less than 0.1mL/m.d.atm, and a water vapor permeability of less than 0.5mL/m.d.atm.

2) Excellent heat sealing performance, it was found through welding strength testing that the heat sealing strength can reach 40N/15mm or more.

3) High transparency, reaching over 96%.

4) Has good biocompatibility, high cell culture density of 2.33 million/ml, and better cell culture effect, suitable for the cultivation of various cells.

5) During sterilization and cell culture processes, there is no precipitation or dissolution of low molecular weight substances.

6) The preparation process is simple, the operation is easy, and the efficiency is high. It can be used to prepare disposable bioreactor bags, storage bags, stirring bags, and feeding bags.

The Structure of Multi layer Coextrusion Film Material for Single Use Bioprocess Bags:

The basic components are: liquid contact layer, adhesive layer, gas barrier layer, adhesive layer, and heat sealing layer.

Liquid contact layer: It should have good biocompatibility and should not have low precipitation during use, which may affect the normal growth and metabolism of cells. The liquid contact layer is a layer that directly contacts the cell culture medium, and ultra low density polyethylene (ULDPE) is currently the most suitable liquid contact layer material discovered, with good compatibility for the cultivation of many cells.

Gas barrier layer: provides isolation function for gases such as oxygen/water vapor/carbon dioxide to reduce the impact of external environment on cell growth. The barrier layer is mostly made of ethylene vinyl alcohol copolymer (EV0H) with a single-layer or two-layer structure. The gas barrier layer provides gas isolation functions such as oxygen/carbon dioxide and is an important component of the process bag film material. The oxygen permeability must be less than 1.0mL/m2.d.atm. The gas barrier layer in the T-bag can be a single layer, such as using ethylene vinyl alcohol copolymer (EV0H). EVOH has good gas barrier properties, but its water resistance and bending resistance are poor, especially when applied to liquid storage bags. Long term and cross regional transportation and storage may lead to antibody inactivation and failure due to the lack of barrier properties.

If you want to increase the barrier performance, you can co extrude PA (aromatic nylon) on the surface of EVOH, and use PA/EVOH/PA three-layer composite film as the gas barrier layer of disposable biotechnology bag film material, which can greatly improve the comprehensive performance of the film material. The PA and EVOH have good compatibility, and there is no need for an adhesive layer between the PA and EVOH layers.

Among them, there are many types of nylon (PA), including aliphatic PA, aliphatic aromatic PA, and aromatic PA. Research has shown that for partially modified aromatic nylon (PA), it is almost not affected by water vapor, and therefore has excellent water vapor, oxygen, and carbon dioxide barrier properties. Therefore, aromatic PA is more suitable for preparing disposable bioprocessing bag film materials, making the resulting disposable bioprocessing bags have higher strength and barrier properties, better water resistance, bending resistance, puncture resistance, and excellent cell culture function.

Heat sealing layer: It provides a certain strength and the heat sealing welding function of the film material. As a film layer that provides self overlapping, docking, and other splicing of film materials, the heat sealing layer needs to meet high-frequency welding and direct heat welding requirements, and provide sufficient heat sealing strength. The volume of a disposable bioreactor determines production efficiency, and large reactors require large volume process bags. This type of membrane material needs to have sufficient strength, and the welded structure needs to be reliable enough to withstand high usage pressure, as well as various bends and possible damages that may occur during the production, folding, packaging, transportation, unfolding, installation, and normal use of the process bag.

Materials and thicknesses of each layer:

Liquid contact layer: with a thickness of 30-200um, the liquid in contact with the liquid contact layer includes cells for cultivation. Experimental results have shown that the thickness of the liquid contact layer ultra low density polyethylene (ULDPE) is more suitable between 50um and 250um. The preferred ULDPE for the liquid contact layer are Dow Engage 8480K Health+, Dow Health+series, and Saudi Arabia based Sabic PCG series.

Gas barrier layer: with a thickness of 30-80um, the nylon layer/ethylene vinyl alcohol copolymer layer in the middle has a thickness of 10-20um, and the nylon layers on both sides have a thickness of 10-30um. Due to the need for low oxygen and water vapor permeability in biotechnology bags, the barrier layer is too thin to meet these requirements; After being too thick, it does not have much significance for the barrier performance, but instead affects the overall processing performance. Therefore, it is preferred to use a thickness of 30-80um. And further experiments were conducted to determine the thickness of PA and EVOH, respectively.

Heat sealing layer: The thickness is 30-150um, and the thickness of the adhesive layer is 5-20um. The heat sealing layer is any one of low-density polyethylene, linear low-density polyethylene, a mixture of low-density polyethylene and linear low-density polyethylene, ethylene vinyl acetate copolymer, or polyurethane elastomer. Flexible materials such as low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), ethylene vinyl acetate copolymer (EVA), and polyurethane elastomer (TPU) are more suitable for heat sealing welding, which can achieve beautiful welding effects and excellent welding strength. The heat sealing layer uses a mixture of low-density polyethylene (LDPE) and linear low-density polyethylene (LLDPE) to improve the transparency of the film material, making it easier for users to observe cell growth during use.

Prepare a heat seal layer using a mixture of low-density polyethylene (LDPE) and linear low-density polyethylene (LLDPE), with LDPE accounting for 20-30% of the mixture.

Adhesive layer: one or more of ethylene vinyl acetate copolymer, ethylene acrylic acid copolymer, and ethylene methacrylate copolymer. The primary function of the adhesive layer is adhesion, and one or more of ethylene vinyl acetate copolymer (EVA), ethylene acrylic acid copolymer (EAA), or ethylene methacrylate copolymer (EMA) can be selected.

The total thickness of disposable biotechnology bag film and the thickness of each layer are mainly considered for the stability of physical properties and the strength of welding to ensure the compliance of bag integrity testing items. The liquid contact layer and the outermost protective layer that come into contact with the cells are relatively thick to ensure the thickness of the welding layer during docking or overlapping, thereby ensuring the heat sealing strength and the integrity of the bag. The thickness of the barrier layer should meet the corresponding gas permeability requirements, and the thickness should be moderate. The adhesive layer only needs to provide good adhesion between the layers, so this layer is relatively thin.