Phenol Formaldehyde Resin

Application :

PHENOSET 1005 ( A double stage Phenolic Resin) provides a glue for use in production of exterior grade plywood conforming to the following plywood specifications.

Bureau of Indian Standards 848 (1974)

This is used in hot bonding only.

Specification :
Appearance Viscous, Dark brown, free flowing liquid
Solubility in water Infinite
Viscosity at 25°C 100 – 150 Cps
pH 9.6 ± 0.5
Density at 25°C

1.21

Packing : 120 kg./240 kg. HDP Carbouys/ HDP Barrel
Storage :

The resin should be stored in a cool place and kept as cool as
possible. At 25ºC, it may be stored for 1 week and for shorter durations at higher temperatures. The limiting factor is the viscosity which will increase as a function of time. The rate of viscosity increase is largely dependent on temperature. Consequently the storage time will be related to the temperature at which the resin is stored. After expiration of the storage time, the resin may still possess its gluing power. However, the viscosity will be so high that the adhesive will be no-longer suitable unless it is more extensively diluted with water in which case the glue mix will have to low a resin content.

Preparation of Glue mix :
Mixing ratio :    
Phenoset 1005 100 parts
Coconut shell flower 10

In preparing the glue mix a mechanical stirrer should be employed preferably one equipped with a wall scraper.

The formulation above will normally give a glue mix with a convenient viscosity for application with a roller spreader.

Pot life            :

When protected against loss of water through evaporation the glue mix will have a pot life of at least 2 to 4 hours provided the temperature is below 30°C (86 °F).

Preparation of the veneers: :

The veneer surface should be smooth, clean and free from dust, waxy and resinous substances. The veneers should be of uniform thickness.

Recommended moisture content of the veneers is 6-8%. Higher moisture contents increase the risk of starved joints and bleed through. When pre-pressing is used, the moisture content should not be less than 5%.

Glue spread :

The glue is applied to one surface only at a rate of 170-180gm/m2, dependent on the veneer quality. These veneers usually have a rough surface and require a heavier spread than thin veneers. When bonding thin veneers it is important to keep the glue spread low to avoid penetration or blisters, especially when the veneer moisture content is high.

Heavier spread than 220g/m2 should be avoided.

To prevent thickening of the glue mix on the roller due to evaporation of water, the rollers should be constantly supplied with fresh glue mix during operation. When operation is interrupted, the rotation of the rollers should be stopped.

Assembly :

To prevent glue failures due to excessive drying out of the glue, which will result in poor wetting of the opposite veneer, it is specially important to maintain a short open time when the climate is hot and dry and low glue spread is used on veneers of low moisture content.

Pre pressing :

Cold pre-pressing is recommended. There is evidence that pre-pressing will improve the bond quality, and it may shorten the hot pressing cycle because handling of the glued assembly and loading of the hot press become easier.

The pressure should be lower than the pressure employed in hot pressing. The most suitable pressure will depend on local conditions and should be established by trials. Experience has shown that 7-12 kg/cm2 , (100-170 lb/in2) give good results. The pre-pressing time also depends on operating conditions. Usually 5 to 15 minutes are sufficient.

Pressure in hot pressing :

The optimum pressure depends on the density of the veneer wood species.

The pressure should be :

(12-14 kg/cm2, 170-200 lb/ in2) with species of a density under 550 kg/m3.

(14-18 kg/cm2, 200-250 lb/ in2) with species of a density above 550kg/m3.

Pressing Times. :

The basic setting times of phenoset 1005 at different temperatures are :

Press temperature in°C 125 130
Basic setting time in min 3

2

To calculate the total pressing time one must add to the above basic setting times the time it takes for heat to travel from the press platen to the farthest glue line. The additional times at different temperatures are :

Distance to the Press Platen temperature
farthest glue line 125°C 130°C
Under 5 mm 0.8 min/mm 0.6 min/mm
5 to 10 mm 1.1 min/mm 0.75 min/mm
Over 10 mm 1.3 min/mm 1.0 min/mm

Example :

For a 7-ply panel with 2.5 mm inner veneers and 1.5 mm back and face veneers, the necessary pressing time at 125ºC can be calculated as follows :

Distance to the innermost glue line : (1.5+2.5+2.5) mm =6.5

Heat transfer time = 6.5 X 1.1 min = 7.15 min
Basic setting time at =

3.00 min

Total pressing time 150ºC = 10.15 min

 

As the rate of heat transfer is dependent on the wood species and its moisture content, the table above can serve only as a guide to the additional time required, and it is recommended to establish the pressing time by trials.

The reactivity of a phenolic resin glue falls off rapidly with decreasing temperature, and the temperature at the innermost glue line should be measured from time to time by means of thermocouples to check that it reaches the desired value.

To ensure that the glue lines are fully cured it is recommended to hot-stack the panels for some hours after removal from the hot press.

Cleaning :

Mixing and spreading equipment must be cleaned before the glue has set. Cleaning is most easily done with warm water. Once the glue has set, it is insoluble and must be scraped off.

Other Highlighting Points :
  1. Because of inherent tack of the Phenoset-1005, it can effectively be used for pre-pressing technique.
  2. Toxicant of choice may be added for glue line poisoning with resin adhesive, Phenoset-1005 to impart resistance against biological agents responsible for decay and thereby to have longer service life.
  3. Treatment of plywood boards made with Phenoset-1005 with preservative compositions based on acid copper chrome or copper chrome boric acid do not alter significantly the bonding property whether treatment is done by soaking process or in vacuum cum pressure impregnator.
  4. No special cares need to be taken for use of Phenoset-1005 except proper working.
  5. Maintenance of excess stock is not required as delivery is prompt.
  6. Formaldehyde emission has not been reported.
Handling precautions :

If the recommended precautions normally laid down for handling chemicals are observed Phenoset-1005 is quite harmless. Due to its high alkalinity the resin can have a caustic effect, and therefore skin contact with the resin should be avoided. Reasonable cleanliness should be exercised, and the hands should be thoroughly washed with soap and hot water before meals and at the end of the working day.