Composition based on Residol (Technical Note: C - 31)

Residol – Partially polymerised cashew nut shell liquid (CNSL) Characteristics Applications Formulations Technical Services

1.0  Residol – Partially polymerised cashew nut shell liquid (CNSL):

The active constituent of CNSL is a meta substituted phenol with long hydrocarbon side chain which on account of its unique molecular structure imparts to CNSL many useful properties leading to its manifold uses in the manufacture of oil soluble resins, varnishes and paints, friction dusts and chemical resistant linings, rubber compounds, bonding resins, adhesives etc.

For most of the above applications, CNSL has to be partially polymerised to a thick viscous liquid consistency, which generally is a time consuming and laborious process.

We are preparing Residol, the bodied material from CNSL, through the action of heat only without using any catalyst. This avoids contamination with other chemicals, which may interfere with its ultimate use.

2.0  Characteristics

Residol has the following Characteristics

Molecular weight 1000 to 1500 Viscosity at 30°C 1500 to 2000 poises Viscosity at 30°C (50% solution in Xylene) 30 to 50 centipoises Iodine value (wijs) 180 to 210 Hydroxyl value 210 to 230 Colour Dark brown to black

3.0  Applications

Residol is comparatively a cheap material and can partly or wholly replace linseed oil and other drying oils and resins in coating formulations where light colour is not a consideration. It retains its phenolic character and can be condensed with Formaldehyde, Hexamine etc., and can be reacted with Styrene monomer, drying oil and synthetic resins easily.

The film of varnishes, enamels and paints formulated from Residol, dry hard either under ambient conditions or on baking. Such films have proved to have high gloss, good hardness and flexibility, resistance to impact, water dilute solution of alkalies, acids and common organic solvents. They have been found to have especially good corrosion resistant properties.

It is advised that basic pigments are not ground with Residol based medium. Such reactive pigments can be added after the grinding process is almost over allowing slight grinding for proper dispersion.

Residol is also a very suitable raw material for use in the manufacture of chemical resistant tiles & cements, adhesives, brake lining dusts, resins etc. Its use with rubber compounds improves their processability, ageing properties, abrasion resistance to oils and above all reduces the cost.

4.0 Formulations

Various formulations for different types of air drying and baking surface coatings, insulating varnishes and other applications have been developed using Residol as the base. As illustrative examples of its applications, some typical formulations are given in the following to be regarded only as suggestive methods.

4.1 Residol – Drying oil varnish:

Residol 500 gms. Low viscosity DCO or Linseed stand oil (15 Poises) 500 gms.

Mixed and cooked at 260-280°C till a string of about 15’’ is obtained. The product is thinned with the Recommend solvent mixture (*) and lead napthanate 1%, cobalt napthanate and manganese napthanate 0.1% or copper octoate (0.05%) as metals mixed as driers.

The film of this varnish dries hard over-night having scratch hardness of about 500 gms. It is not affected by water and 5% sulphuric acid solution for 4 days it however, slightly wrinkles after 24 hours in 5% sodium carbonate solution. The varnishes using DCO have comparatively faster drying time than the linseed oil varnishes.

(*) Recommend solvent mixture: Most of the compositions based on Residol dissolve easily in mineral turpentine (white spirit) or wood turpentine. In case the composition does not dissolve fully, use a mixture of mineral turpentine and coal tar napatha or xylene or toluene is recommended. The proportion of 2:1 between mineral turpentine and coal tar naptha or xylene has been found to be generally very satisfactory.

4.2 Residol – Drying Oil – Ester Gum Varnish:

 

Residol 200 gms. DCO or Linseed 100 gms. Ester gum 100 gms.

Residol and the drying oil are mixed and heated at 160°C. Ester gum is then added in small portions for 15 minutes. The temperature is raised to 240°C and maintained at that level till a string of 16 to 18 inches is obtained.

The cooked material is thinned down to 50% non-volatile by the Recommended solvent mixture (*) lead napthanate (1.0%) and cobalt octoate (0.1%) are used as driers.

The film dries in air (hard) in 8 hours and 30 minutes at 120°C having hardness of about 1000 gms. The flexibility is satisfactory and the film remians unaffected by water (48 hours), 5% sodium carbonate solution and 5% sulphuric acid solution (24 hours).

The is also resistant to white spirit upto one hour.

The iron oxide paint prepared as per IS. 123-1962 dries wihtin about 6 to 8 hours to chocolate colour having good and uniform gloss and excellent adhesion. It acts as a very suitable primer for structural steel railway wagons and steel furniture. It is also a very satisfactory electric insulating varnish.

4.3 Residol – Drying Oil – Modified Phenolic Resin Varnish:

If in the above composition given in 4.2 an equivalent amount of modified phenolic resin such as Silex 85 is replaced for Ester gum and the cooked materials are thinned down to 50 percent non volatile with the recommended solvent mixture (*) and driers added as usual, the dying time of the film is reduced considerably, its scratch hardness is about 1100 gms, after 48 hours, tested according to I.S. specifications.

Alternatively, it can be baked at 120°C to get harder films.

The films have good flexibility and are resistant to water and white spirit (48 hours), 5 percent Sodium carbonate solution and 5 percent sulphuric acid solution (24 hours). It also acts as good baking insulating varnish conforming to I.S:350:1964.

4.4 Aluminium Paints:

Residol probably finds its widest application in the preparation of high quality Aluminium paints. The following is a proved composition for such paint.

 

Medium (Residol – Drying Oil – Estergum Varnish as per 4.2) 100 gms. White spirit 100 gms. 66% leafing aluminium paste 30 gms.

The varnish is prepared first by the procedure given in our composition 4.2 and by thinning it to 50% non-volatile by the recommended solvent mixture (*). The 66% leafing Aluminium paste is added and the mixture is thoroughly agitated. Finally, lead napthanate (1%), cobalt (0.1%) and Manganese napthanate (0.1%) are added as driers.

This paint gives bright, lustrous and smooth finish and dries hard within 6 hours. The film when baked for one hour at 60°C and then kept in humidity cabinet under a temperature cycle of 42 to 48°C for a week remains unaffected.

This has very satisfactory anti-corrosive properties.

4.5 Residol – Alkyd Varnish:

 

Residol 500 gms. 66 per cent Linseed oil alkyd resin 250 gms.

They are mixed and heated 260°C for about half an hour when a string of about 18-20’’ is obtained. The product is cooled and thinned with an equal weight of the recommended solvent mixture (*) Manganese (0.1%) and Lead (1.0%) as metals are added as driers.

The film dries within 7 or 8 hours with a scratch hardness of about 800 gms. It has a very high gloss and is particularly suitable for application for outdoor coatings.

The film of this varnish when baked for half an hour at 150°C dries hard with a scratch hardness of about 1900 gms. and has good adhesion and flexibility.

The above is also recommended as suitable composition for electric insulation varnishes.

4.6 Sewing machine & Cycle Enamel:

Black enamels suitable for sewing machine and bicycle industry can be prepared from the above two varnishes (compositions 4.3 and 4.5) by grinding 3 percent carbon black on the weight of non volatile and adjusting the consistency to 40 to 45 seconds at 30°C by Ford cup No.4.

The recommended baking schedule for these enamels is for 30 minutes at 150°C or 15 minutes at 190°C. The scratch hardness of film has been found to be 1600 gms. and 1700 gms respectively. The gloss, flexibility as well as resistance to water and chemicals are excellent in both cases. They have also withstood satisfactorily 10½ lbs. weight impact.

4.7 Residol – Alkyd Resin – Formaldehyde Air Drying Varnish:

Residol 500 gms. 66 percent long linseed oil alkyd resin 500 gms. Hexamine 125 gms. Mixture of white spirit and light coal tar naphtha or Xylene (1:1) 1000 gms.

A mixture of Residol alkyd resin and mixture of white spirit and tar naptha or xylene are heated under reflux of hexamine is added during 15 minutes. The temperature is raised to 150 to 160°C and heated for another 15 minutes. The solution is cooled to about 100°C and the usual amount of cobalt, lead and manganese driers are added.

The film of the varnish driers within 6 to 7 hours with the scratch hardness of 1000 gms. with excellent adhesion and flexibility. It is unaffected by water, 5 percent sulphuric acid solution and white spirit for 48 hours and has good weather resistance properties.

4.8 Residol Manganese Dioxide Varnish:

 

Residol 100 gms. Manganese 4 gms.

Residol is heated to 100°C and Manganese Dioxide is added slowly and the temperature is maintained between 280°C and 290°C till 18’’ string obtained.

Then it is thinned to 50% with the recommended solvent mixture (*) and driers are added in usual quantity. The film dries 10 hours in air and in 40 minutes when baked at 120°C. The scratch hardness is 800 gms. and it is resistant to water (76 hours no effect) and chemicals. It is quite suitable for primer coatings as such or by incorporating little plasticiser (2.5% per solids) such as tricresyl, phosphate etc.

4.9 Zinc Chrome-Iron Primer As Per: 2074

Medium (Varnish) 30 by parts Zinc chrome 85 by parts Iron oxide 270 by parts Talc 45 by parts White spirit 19.5 by parts

The varnishes mentioned in 4.2 or 4.7 or 4.8 can be taken as the media. The film characteristics or the above formulated primer satisfy I.S.:  101-1964. It withstands the corrosion cabinet test and sea water immersion tests for 2 weeks.

4.10 Brake lining dust composition:

Residol 300 gms. Sulphuric Acid 3 gms. Paraformaldehyde 24 gms.

Residol is mixed well with the Sulphuric acid and heated to 240°C for about 15 minutes. Then it is mixed thoroughly with Paraformaldehyde using a triple rollmill. The mixture is then heated to make it a hard gel. The hardened gel is powdered and seived through 200 mesh. The acetone soluble matter will be less then 3 per cent.

4.11 Chemical resisting tiles and cements:

 

Residol 300 gms. Paraformaldehyde 24 gms. Silica fillers or barytes 600 gms.

Above ingredients are mixed thoroughly using a triple rollmill or heavy duty mixers. Then it can be moulded in the form of tiles or bricks. This material sets within 4 hours and hardens gradually to a hard mass. The tiles are unaffected by the mild acids and alkalies and common organic solvents.

4.12 Adhesive for insulating tape and cable cloth:

 

Residol 80 gms. Rosin 20 gms.

Residol is heated to 160°C and rosin is added slowly and finally cooled till astring of 16” is obtained. It is then thinned to 80% solids with white spirit and applied on cloth tape.

5.0 Technical Services

The Services of our well equipped application Laboratory and the technically qualified staff are at your disposal to provide further technical 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.

Caution: Because we cannot anticipate the conditions under which our products 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.