Remix each of the two components (parts A and B) every time before using.
1. Mixing of the two components
Mix the two product parts BLUESIL RTV A and BLUESIL RTV B according to following mix ratios:
The two components may be intimately mixed either by hand or by means of a lowspeed electric or pneumatic mixer to minimize the introduction of air into the mixture.
|Mixing ratio: ||A : B = 1 : 1||A : B = 10 : 1|
After mixing BLUESIL RTV 31xx A&B, it is recommended to eliminate entrapped air. If the mixing is done with the help of a machine both parts are degassed before mixing.
The BLUESIL RTV 3120 A&B and BLUESIL RTV 3128 A&B are degassed under a vacuum of 30 to 50 mbar. Under vacuum, the product expands 3 times its initial volume and forms bubbles on its surface. These bubbles will disappear gradually and the mixture will sink back down to its initial volume within 5 minutes. Release the vacuum and repeat the operation a few minutes later.
Remark: release the vacuum several times imes the degassing. For easier degassing only fill a recipient to 1/3 of its height.
3. Cross linking
The best curing conditions are at 23?C. When using the products at higher temperatures, the pot life is shorter and the setting rate faster. As opposed to this, lower temperatures increase the pot life and decrease the setting rate.
Room temperature curing assures the lowest possible shrinkage, if accelerated cure is desired, mild heat should be preferred. To minimize shrinkage cure the elastomer at maximum temperature of , higher temperatures will cause higher shrinkage.
At 23?C, the moulds can be demoulded after the time indicated as ""demolding time"""""" (see § 2.Polymerization).In order to achieve the best possible performance levels from the moulds, it is preferable to wait for 24 hours before using them.
Be aware that contact with certain materials can inhibit the curing of this RTV:
- Natural rubbers vulcanized with sulphur
- Polycondensation RTV catalysed with metal salts
- PVC stabilizing agents
- Amine cured epoxies
- Sulphur containing clays.
If doubts exist it’s recommendable to run a quick test with a small quantity of material in order to assess compatibility. Take duly note that cross contamination due to not well cleaned tools or devices is frequently the main cause of inhibition. The best way is to use only dedicated gear when processing polyaddition RTVs.
4. Processing aids
4.1 Adhesion promoters (""""""primers"""""")
In order to achieve adhesion of BLUESIL RTV 3120 A&B and BLUESIL RTV 3128 A&B on the pad support, it is recommended to prime the support with an adhesion promoter. Bluestar Silicones recommends the use of primer PM 820 and primer PM 811 A&B according to the instructions below.
For more detailed information, please refer to the Technical Data Sheets of the Primers.
|PRIMER PM 820||PRIMER PM 811 A&B|
|Substrate||Metal (steel, aluminum), plastic (polyester), reinforced resins|
|Pot-life A+B||n.a. (monocomponent)||> 3 days|
|Usage level||Very thin layer (30÷60 g/m2)|
- Application of PM 820
- Wait 30 minutes
- Application of PM 811
- Wait 30 minutes up to 7 days
- Application of RTV-2 Silicone
|Application by||Spray, brush, cloth|
4.2 Pot-life accelerator / retardant
Should it be desired to change the polymerization time of BLUESIL RTV 3120 A&B and BLUESIL RTV 3128 A&B, following additives allow a customization by increasing the pot-life (retarder PA 40) or by shortening it (accelerator PA 39). Information on their use is shown in the table below.
The effects of the two additives on the pot-life are shown in the following graphs.
|ACCELERATOR PA 39||RETARDANT PA 40|
|Usage level||0.1 ÷ 3 %||0.1 ÷ 5 %|
|Use||Mix PA 39 into Pt catalyst part||Mix PA 40 into base part|
For more detailed information, please refer to the Technical Data Sheets of the single Additives.
4.3 Oil dilution"""
The hardness of BLUESIL RTV 3120 A&B and BLUESIL RTV 3128 A&B can be adjusted by means of a non reactive silicone oil, that plasticizing the silicone network lowers the material hardness. BLUESTAR SILICONES offers the low viscosity silicone BLUESIL FLD 47 V 50, that can be added to the BLUESIL RTV 3120 A&B and BLUESIL RTV 3128 A&B as schematically shown in the following graph.
|STORAGE t < +40°C IN ITS ORIGINAL PACK||Store in a cool, dry place with adequate ventilation. Keep away from incompatible materials, open flames, and high temperatures. Store in tightly closed original container. equipped with a degassing device. Suitable containers: polyethylene. Steel drums coated with epoxy-resin.||请查阅这个产品的物质安全数据表|
BLUESIL RTV 3120 B
The BLUESIL RTV 3120 A&B and BLUESIL RTV 3128 A&B are two component silicone elastomers which cure at room temperature by a polyaddition reaction.
This reaction can be accelerated by heat.
- High purity products particularly designed for printing pads production.
- Good mechanical properties.
- Excellent heat stability.
- Adjustable hardness by diluting with silicone oils.
These products are specifically formulated for the production of printing pads.