SikaBiresin® PX840

Vacuum casting soft polyurethane for prototypes and technical parts

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SikaBiresin® PX840 is a 3-component vacuum casting polyurethane system for prototypes and technical parts.  

  • Three components for variable hardness
  • Can be easily colored with CP colors
  • Low aggressiveness against silicone molds
  • Easy processing
 
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Overview

PRODUCT BENEFITS

  • Three components for variable hardness
  • Can be easily colored with CP colors
  • Low aggressiveness against silicone molds
  • Easy processing
 

Areas of Application

SikaBiresin® PX840 is designed for the manufacturing of soft prototype parts and small series of rubber like parts by vacuum casting in silicone molds. It is fully compatible with SikaBiresin® SI291 silicone molds.
This product is suitable for experienced professional users only. Tests under actual processing conditions and with additional materials such as coatings and release agents must be performed to proof material compatibility.
   

Packaging

  

SikaBiresin® PX840 (A)

Box with bottles

6 x 1 kg

SikaBiresin® PX840 (B)

Box with bottles

6 x 1 kg

SikaBiresin® PX840 (C)

Box with bottles

6 x 1 kg

Product Details

Properties

SikaBiresin® PX840 (A)

SikaBiresin® PX840 (B)

SikaBiresin® PX840 (C)

Chemical base

Isocyanate

Polyol

Polyol

Color

 

mixed

Yellowish

Transparent

Milky white

Off-white

Density

 

cured

1.2 kg/l

1.0 kg/l

1.02 kg/l

1.14 kg/l A

Mixing ratio

by weight

100 

100

0 ─ 500

Viscosity (CQP538-2 / BROOKFIELD LVT)

 

mixed

700 mPa·s

425 mPa·s

900 mPa·s

550 mPa·s

Pot life (CQP021-3 / Gel Timer TECAM)

100 g at 23 °C

12 minutes

Demolding time

120 minutes

Curing time

at 23 °C

5 days A

Maximum casting thickness

20 mm

Shore A hardness (CQP023-1 / ISO 868)

95 A

see table 1

Tensile strength (CQP036-6 / ISO 37)

20 MPa A

15 MPa B, C
7 MPa B, D
6 MPa B, E

Tear strength (CQP045-1 / ISO 34)

60 kN/m A

29 kN/m B, C

10 kN/m B, D

9 kN/m B, E

Elongation at break (CQP036-2 / ISO 527)

4 % A

680 % B, F

Shelf life

9 months

9 months

12 months

CQP = Corporate Quality Procedure

A) curing condition: 70 °C for 16 hoursB) curing condition: 70 °C for 24 hoursC) Extender 150 parts
D) Extender 350 partsE) Extender 450 partsF) Extender 150 ─ 450 parts

Application

METHOD OF APPLICATION

The material and processing temperature shall be between 18 °C – 25 °C. Temperature of a silicone mold shall be 70 °C.
The material can only be used in a vacuum casting machine.

Select based on the table below the required amount of extender to achieve the desired Shore A hardness.

Hardness Shore A

Extender (C)

950
8550
7575
65150
60200
50250
40350
30450
25500

Table 1: Shore A with different extender amount, post curing: 24 hours at 70 °C

Application

Immediately after mixing pour the product into the preheated silicone mold. After casting, place the mold in a preheated oven (70 °C) for 120 minutes to cure.
Further post curing of the demolded part can improve the final mechanical properties.
Depending on the geometry and weight of the part, it is recommended to use a conformer while post curing.

STORAGE CONDITIONS

Both components must be stored at temperature between 15 °C and 25 °C in original unopened containers.

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