ALKYD RESIN 3 PART NOBAKE BINDER
The product
COTCURE A is alkyd resin, which is activated by driers and catalyzed by isocyanate. The resin binder can be used for medium and heavy moulds and cores in ferrous or non-ferrous foundries.
Advantages
» Air setting process; no heating or gassing is required.
» Excellent surface finish of the casting.
» Excellent flowability of sand and less sticking to the pattern.
» Fast and through setting; requires less reinforcement.
» Good dimension accuracy.
» Excellent storage life, cores can be stored for many days without deterioration in strength.
Application
1. Choose washed sand (AFS 50 - 60), clay should be 0.2 - 0.5% .
2. Premix COTCURE A and COTCURE B and add to sand in a mixer. Mix for 2 - 3 mins. Add COTCURE C and mix for 1 - 2 min.
3. Typical addition level.
| SAND | New sand 100 parts |
| COTCURE A (Alkyd resin) | 2% by weight of sand. |
| COTCURE B (Activator) | 5 - 10% by weight of part A |
| COTCURE C (Catalyst) | 20 % by weight of part A |
| COTCURE C (Catalyst) | 28 - 30 °C |
The following factors directly affects the Bench life of the mixed sand.
Increase in bench life
» Lower ambient temperature
» Cold sand
» Lower proportion of Activator
» Wet sand ( to be avoided )
» Clay content is more than 0.5%
Decrease in bench life
» Higher ambient temperature
» Hot Sand
» Higher proportion of catalyst
The activator level can be varied to influence to bench life. Shop floor adjustment needs to be made on actual trials.
4. Fill the moulds and core boxes quickly. Filling should be completed well within bench life to ensure moulds and cores are not weak or friable.
5. Typical bench life and Strip time.
Range of activator is available for achieving desired strip time.
| Bench life | Strip time | |
| Sand mix with Part A, B and C | 12 - 15min | 40 - 45min |
The figures are given as guidelines. The actual strip time depends on moulds and cores size, shape and ambient conditions. Also the bench life and strip time can be altered as per need by use of different catalyst grade.
TYPICAL SAND TEST RESULTS:
The sand quality and ambient conditions are same as given under bench life and strip time.
| Time elapsed after sand mix Preparation | Compression strength of 2 x 2 std. Specimen |
| 1st hr. | 4kg. ± 10% |
| 2nd hr. | 16kg.±10% |
| 4th hr. | 24kg.±10% |
| 24th hr. | 50kg. Min. |
Gases - 15cc/gm. Max. at 1000°C for 2 min.
Standard packings
| COTCURE A | 190KG. M.S BARREL |
| COTCURE B | 20KG. DRUM |
| COTCURE C | 40 KG. DRUM |
Shelf life - up to 3 months at 30°C
