CNSL and Cardphenol Modified Resins (Technical Note: ST 12)

Introduction Specifications Applications Typical Paint Formulations Storage Technical Service

1.0 Introduction

Silex 75 and Silex 85 are CNSL & Cardphenol based Phenolic Resins modified with Rosin and Rosin/Bitumen respectively. They are Dark Reddish Brown & Golden Yellow resins and are suitable for Dark coloured Synthetic hard glossy enamels, insulating Varnishes, Aluminium Medium, having outstanding film properties. Silex 75 is particularly suitable for baking type of finishes giving very hard glossy film. Silex 85 is Cardphenol based Phenolic resin having Golden Yellow tone, especially made for light coloured compositions.

1.1 Compatibility with Drying Oils: Silex 75 and 85 are compatible in all proportions with drying oils (Linseed Oils, DCO etc). Their compatibility with other resins like alkyds epoxies is also very good.

1.2 Solubility: Silex 75 and 85 are soluble in most of the aromatic and aliphatic hydrocarbons. Eg. Mineral Turpentine Oil (MTO), Xylene, Solvent Naphtha etc.

1.3 Recommended Driers: Drier combination such as 1% Lead or 0.4% Zirconium, 0.1% Cobalt and 0.1% Manganese as metals on the solid content of the resin, with ageing of atleast 24 hours is recommended. The films of Silex 75 and 85 dry hard in air, under ambient conditions in about 2 to 3 hours when recommended driers are added. The dried film is clear, glossy and of Gloden Yellow to Dark Reddish Brown colour with excellent properties like adhesion, hardness, flexibility and good resistance to water and chemicals. The film dries hard within 15 to 20 minutes when baked at a temperature of 120°C.

1.4 Mode of Supply: The above resins are supplied in 200 and 20 kgs packing in 100%, 80% and 65% solids in MTO. For most of the common paint and varnish applications the 80% or 65% executions are recommended as they have better film properties.

1.5 Silex 75 & Silex 85 along with suitable driers can be used as good film formers. However, if still better film properties like flexibility are desired, they are to be modified with suitable drying oils or other resins like alkyds, epoxies etc.

 

2.0 Specifications

Properties Silex 75 Silex 85 1. Colour Clear Dark Reddish brown Golden Yellow 2. Consistency Semi Solid Same 3. Viscosity of 100% (50% solids in MTO of 80% at 25°C) Poises of 65% 1.5 to 2.0 1.0 to 1.5 2.0 to 3.6 2.25 to 3.0 5.5 to 8.5 3.5 to 4.6 4. Acid Value  Less than 12 Same 5. Volatile Matter Less than 25 Same 6. Rosin Content 20% 20%

2.1 Film Characteristics: The film characteristics have been studied by making the resin to 30% solids in mineral turpentine, driers added are 1% lead, 0.1% cobalt and 0.1% manganese as metals in their octoates and the varnish is left for 24 hours for ageing, properties as per IS: specifications 197-1972.

Properties Silex 75 42 oil length Rosinated Alkyd Varnish (50% Solids) Silex 85 1. Colour Reddish brown Light Pale Golden yellow 2. Drying time Surface dry About 1 hour 5 hours Same Hard Dry 100% About 3 ½ hrs 5 hours 3 hours Hard Dry 80% About 3 hours 5 hours 2 ½ hours Hard Dry 65% About 2 ½ hours 5 hours 2 hours 3. Scratch Hardness 1000 grams 800 grams 1000 grams 4. Flexibility Good Good Better Good 5. Adhesion Good Good Good Good 6. Resistance to water NE (100) SB (8) NE (100) 5% Sodium Carbonate NE (80) SB (25) NE (100) 2% Sulphuric Acid NE (100) SB (48) NE (150) White Spirit NE (100) NE (100) NE (100) Linseed Oil NE (100) SB (100) NE (100)

NE – No effect, figures within brackets indicate number of hours tested.

Hard Drying Time – Measured of 30% solid solution in MTO at 30°C with recommended driers.

 

3.0 Applications

3.1 Primers: As Silex resins are having good water, chemical and corrosion resistance, the primers based on the above resins have excellent properties.

3.2 Baking/Air Drying Hard Gloss Synthetic Enamels: The enamels based on Silex 75 and 85 exhibit high gloss and excellent hardness, water and chemical resistance. Silex 85 particularly yields a very hard glossy film when baked.

3.4 Cycle Stoving Enamels: The Cycle Stoving Enamels based on Silex 85 have better hardness and film properties in addition to excellent gloss.

4.0 Typical Paint Formulations

Some Typical Paint Formulations based on the above Silex resins are given below as illustrations.

4.1 Aluminium Paint (Dual Pack Leafing Type)

1) Silex 85 (65%) 8 parts by weight 2) MTO* 10 parts by weight 3) Silicon Surfactant 0.1% parts by weight Add driers as recommended 4) Aluminium Leafing Paste (66%) solids 2 parts by weight separately packed.

4.1 Smoke Grey Paint (Hard Gloss Enamels)

1) Titanium Dioxide 12 parts by weight 2) Barytes 20 parts by weight 3) Talc 7 parts by weight 4) Prussian Blue 1 part by weight 5) Silex 85 (80%) 75 parts by weight 6) MTO* 45 part by weight

4.2 Air Drying/Stoving Insulating Varnishes

1) DCO Stand Oil 14 parts by weight 2) Silex 85 (80%) 47 parts by weight 3) MTo/Xylene* 40 parts by weight

Add driers as recommended.

4.3 Redoxide Primers  

1) Redoxide 6.5 parts by weight 2) China Clay 3.5 parts by weight 3) Silex 75 (65%) 7.7 parts by weight 4) MTO* 2.3 parts by weight 5) Aluminium stearate and wetting agent 0.1 part by weight

Add driers and grind to 6 fineness in Hegemon Guage (0.02 in).

4.4 Olive Green Enamel

1) Silex 75 (65%) 7.7 parts by weight 2) Chromium oxide green 5.2 parts by weight 3) China clay 3.0 parts by weight 4) Middle Chrome 0.3 part by weight 5) Carbonblack 0.1 part by weight 6) MTO* 2.3 parts by weight 7) Wetting agent 0.1 part by weight

Driers as recommended.

Grind it to 7 to 8 fineness in Hegemon Gauge (.02 in).

4.5 Impregnating Varnish

1) Silex 85 (65%) 7.5 parts by weight 2) DCO or stand Oil 2.5 parts by weight

Mixture is heated to 160°C and thinned down in MTO to 30 to 40 Sec. In ford cup 4.

4.6 Black Enamels

1) Silex 75 (65%) 10 parts by weight 2) MTO* 6.5 parts by weight 3) Carbonblack 0.325 part by weight 4) Wetting agent 0.1 part by weight

Add Driers as recommended

*MTO quantity can be varied to suit the desired final viscosity.

5.0 Storage

The storage stability of Silex resins is satisfactory atleast upto 6 months, if stored in tight containers in a cool place.

6.0 Technical Service

We have well equipped Research and Development Laboratories and are in a position to provide detailed Technical informations and suggestions in regard to the application of these resins.

Caution: Because we can not anticipate the conditions under which our product may be used, we do not guarantee the applicability or the accuracy of the above information. Users should make their own tests to determine the suitability of our products for their particular purpose. The products are sold without any such warranty either by express or implied. Moreover the above information is not intended as recommendation to use our product in the infringement of any patent.