Why should we choose a 'High Temperature Vacuum Bagging Sealant' HT Tape over Normal tape RT/ Low Temperature Tape for autoclave composite manufacturing?

 

Composite materials are manufactured by different methods like hand layup, spray up, Vacuum bagging, resin infusion, prepreg layup, Autoclave moulding, filament winding, pultrusion etc.

We will be explaining:

·       Rubber type

·       Temperature

·       Adhesion(Peel Strength, Lap Shear Strength)

·       Penetration

·       Uniform Size Consistency

·       Shelf Life

·       Removal after the process

·       Solid Content

These are the main Characteristics for the Tape that play a role in the process of sealing vacuum.

 

Wherever a vacuum comes to play there you require a seal to arrest the movement of air. In vacuum bagging, Prepreg Lay-up, Autoclave moulding, Resin infusion/VARTM vacuum these tapes are used. The low temperature rubber tacky tapes are usually used in vacuum bagging, Resin infusion, Marine and Industrial FRP where the temperature is in the range of room to 140 or 150 degree C the maximum. The heat generated through the process or the infused resin will be in that range. The High temperature vacuum bagging sealant tape or the high temperature tacky tape is used in autoclave moulding, Prepreg layups where the temperature is raised above 150 degree C.

You can create a vacuum using a vacuum pump but the outside air should be sealed perfectly. This sealing is created by a rubber tacky tape where the tape should adhere to the substrate and the bag without leaving any gap, the tape should be super flexible to accommodate or adjust the shape of the mould substrate. It should be tacky or sticky to the Mold substrate, bagging film thus sealing the pleats, overlaps and corners.

Rubber Selection

A variety of rubber polymers are available like EPDM, Silicone Rubber, NBR, Butyl, Natural Rubber but the one with a low permeability polymer should be chosen as the base rubber. Centroid deals , process all these rubbers and modified polymers are available. We choose the lowest permeable material as the base rubber.

Temperature

The tape should not melt, lose its tackiness, should not harden during a wider temperature range as the process moves from a low temperature to high temperature. The atmospheric temperature can be as low as 5 or 10 degree C but the tape should not be brittle. So a wider flexible temperature is the need. The Black or low temperature tape withstands up to a temperature of maximum 150 degree C and can be used in process in that temperature range, whereas the yellow or high temperature tacky tape will easily withstand the temperature range of 210 degree C and got peel off without any residue.

Adhesion

It’s the next most important thing as if the vacuum bagging sealant tape is not tacky enough to the substrate and bag it creates gaps or voids which lowers the vacuum and results in defective part, part without uniform strength over the surface, surface defects. Once it is applied it should not peel off during the normal operation and preparation where vacuum tends to create a shearing and peeling force.

Penetration

This measures the softness / flowability of the tape in turn gives the flexibility. The Mold surface and shapes can be too complex that the tape should be able to seal it over by the soft and flexible nature, any angle or any notches should be sealed properly during application and should not hinder the application procedure. It should feel like a zip put around the bag, that feeling should be there for the applicator.

Uniform size consistency

The tape should have uniform size in width and thickness, as large size difference will create a change in different areas. We are able to custom size the tape based on the vacuum or pressure applied like increasing the width thereby increasing the contact area and thus increasing the overall peel adhesion and sealing.

Shelf Life

The Tapes are packed in quality carton boxes specially design and manufactured in such a way that it will not stick to each other or will not ooze out of the coated paper. Our tapes are having a shelf life of 1 year + based on the storage conditions.

Removal after the Process

The tapes should be easily removable after the vacuum bagging process as it should not leave any residue over the mould surface during removal. The local or non-tested tape may become sticky, flows over the mould surface making it difficult to remove from the Mold surface and will destroy your costly Mold. So the properties and quality matter. Our High temperature tape technology is explained over here.

Solid Content

Our High temperature tapes have a 100% solid content which will not vaporize over heating or high temperature autoclaving and will not affect the vacuum bagging parts at all.

If you need more technical details or like to buy our tape , Contact Us

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