Benefits of Using Batch Inclusion Bags:

1. Improves quality and batch to batch uniformity
   • insures 100% of compound ingredients go into the mixer
   • when doing in-house weighings, batch inclusion bags eliminate the risk of cross-contamination due to chemical residue in tubs and weighing containers
2. Increases productivity
   • eliminates the need to weigh ingredients in-house through the use of pre-weighed additives
   • eliminates the need to clean out tubs and weighing containers
3. Reduces product loss due to spillage and minimizes the accumulation of costly additives in the dust collectors
4. Reduces solid waste disposal costs
5. Improves cleanliness of the mixing area
6. Minimizes worker exposure to hazardous materials

  
Choosing Your Batch Inclusion Packaging:

Along with the melting point, it is important to consider the following film and bag properties when choosing the appropriate packaging:

1. Physical properties of the film or bags
   • tensile
   • elongation
   • elmendorf tear
2. Chemical resistance of the film
   • some chemicals and oils may attack certain types of packaging before the bag’s contents are thrown into the mixer
3. Water vapor transmission rates of the film
   • consider if the contents of the bags are moisture sensitive such as desiccants
4. Heat sealability of the film and bags
5. Cost
   • usually, the lower the melting point, the higher the cost.
   • higher melting bags (>95°C) will usually have stronger physical properties, better chemical resistance, and lower water vapor transmission rates.
6. Size

Clearly, the amount of material being put in the bag will be a key factor. However, you should consider how the bag will be used before finalizing its size. For example, if you do not heat seal the bags, you will need extra film at the top to fold over the bag opening to prevent spills or contamination. If you heat seal the bag, a shorter—and therefore less costly—bag can be used.

Professor J.D. Lomel says, "Never tie a knot in a batch inclusion bag and throw the knot in the mixer because it will not disperse!" For more helpful tips, ask Prof. J.D. Lomel.

Also consider how the bags will be handled. If the bags are lifted and carried through the plant, a thicker bag will be needed. If they are used as tub liners and remain in the tubs until dumped directly into the mixer, a thinner, less costly bag can be used. The bag thickness is typically in a range of 2.0-3.0 mils (50-75 microns).

Keep in mind that the most cost effective bag choice will be the smallest and thinnest, and have highest melting point required for the job.

  
Glossary

Batch Inclusion - Term used when the ingredients and packaging materials are thrown into the mixer or onto a mill. The packaging melts and disperses into the rubber, becoming a minor part of the compounded product.

Melting Point - The temperature where all crystallinity in the film is destroyed so the film can completely incorporate itself into the rubber.

Vicat or Softening Point - The temperature where changes in the physical properties of the film become noticeable. The film weakens and becomes soft, stretchy, and sticky.

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