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Wood Weld Standard - 1kg
Construction Chemicals Wood Weld Standard is a moisture-curing, single part, polyurethane adhesive, specifically designed for applications in the panel manufacturing and laminating industries, where it is required to bond many types of plastic foams and other insulating materials to a wide variety of both rigid and flexible facing materials. Such composites form structural sandwich panels and insulated building boards and may be used in the manufacture of cold stores, caravans, mobile home and offices, insulated building units etc.
SURFACE PREPARATION
Materials to be bonded should be clean and free from dust, grease and other contaminants. Metals should be stored in a warm environment prior to bonding to avoid chilling of the glue line, which leads to extended cure times.
Most pre-finished metals have backing coats which are well suited to bonding.
Some grades of Aluminium, Galvanised Steel and plastics, however, can be difficult to bond and may require the use of a primer. A test panel should always be prepared when new materials are to be used to establish the adhesive’s compatibility.
ADHESIVE APPLICATION
The adhesive is applied by trowel, notched scraper, hand roller, coater or an automatic bead applicator to one surface only of each glue line.
The amount required will vary according to the porosity/smoothness of the substrates and the means of application, but will normally be in the range 80 – 140 grams per square metre.
Once the adhesive has been applied it should be over-misted with water (approximately 5 – 7.5% of water based on the adhesive coating weight is the optimum amount – excessive amounts of water should be avoided).
The panel is then assembled as soon as possible to minimise water evaporation and placed under pressure within the open time of the adhesive. The pressure required will depend to a great extent on the nature of the substrates, but is usually in the range 0.5 to 0.9 bar.
Pressure should be maintained until the adhesive is sufficiently cured to permit handling of the bonded item. Full cure of the adhesive is not obtained for 24 hours and handling within this period should be kept to a minimum.
The open time and cure cycle to permit handling will vary according to:
1. Temperature
2. Weight of adhesive applied
3. Weight of water overmist
4. Method of working
5. Substrates being bonded and should always be determined by experiment.
Temperature ºC 15 17.5 20 22.5 25
Open time minutes* 21 18 16 13 10
Cure time minutes* 50 45 40 32.5 25
Processing Guide
Weight of adhesive 80 – 140 g/m² Water overmist 4 – 10.5 g/m²
* measured from when the water overmist is applied.
Various modifications of Construction Chemicals Wood Weld Standard have been developed to accommodate different production requirements; these products have different open and cure times.
The modifications currently available are listed below in order of their speed of cure:
CLEAN DOWN
Construction Chemicals Wood Weld Standard when uncured can be removed with cleaning Solvent 6 or Solvent 9.
Cured product will prove very difficult to remove: however, soaking in Solvent 6 overnight will soften the adhesive.
Nozzles from automatic bead applicators should be immersed in a non-reactive plasticiser when not in use.
STORAGE AND HANDLING
Construction Chemicals Wood Weld Standard is a moisture sensitive adhesive and, left in contact with the open atmosphere, will eventually gel. For this reason, Construction Chemicals Wood Weld Fast Set is protected with a blanket of Nitrogen in the drum prior to despatch, which forms a dry, inert layer on top of the adhesive.
The adhesive under these conditions will have a storage life in excess of three months, provided the containers are stored unopened in a dry place at a temperature between 4ºC and 25ºC.
Once the container has been opened for use and the inert blanket replaced by moist air, the adhesive will have a limited life. To eliminate the moist air reacting with the adhesive, a Nitrogen cylinder can be connected to the small bung hole of the drum, via suitable pressure-reducing valves, to give a positive pressure of 1 – 2 psi.
Alternatively, a desiccator can be connected to the small bung hole of the drum, which will dry the incoming air, replacing the adhesive used. A suitable desiccator with the relevant pipework can be supplied by Construction Chemicals. This will last for approximately 3 months prior to regeneration. Further information is available upon request.
If water enters the drum of adhesive, it will react, giving off carbon dioxide which can cause over-pressurisation of closed cans and drums.
HEALTH AND SAFETY
Construction Chemicals Wood Weld Standard contains Diphenyl Methane Diisocyanate (MDI) which is harmful if inhaled. Use with adequate ventilation and avoid contact with skin and eyes by wearing suitable protective gear.
The vapour pressure of MDI at 20ºC is low and therefore by normal production techniques like roller coating, spreading or beading, very little diisocyanate vapour will be present in the air.
After contact with the skin, wash immediately with soap and water.
After contact with eyes, irrigate with copious amounts of water and seek medical advice.
TECHNICAL DATA
Base Polyurethane
Solids 100%
Viscosity 4000 ± 500 cps @ 25ºC
Colour Brown
Tack life N/A
Coverage Up to 12.5m² per kg
Cleaner Solvent 6 or 9
Flash Point Above 150ºC
Shelf Life 6 months unopend
Wood Weld Standard HHealth & Safety & Technical Data Sheet
Price:
£19.25
excluding VAT
Quantity:
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