GENERAL:

Introduction:
Alfas seal is foamed flexible pvc with a self-adhesive layer of acrylic composition applied either to one face (single sided - ss) or to both faces (double sided - ds). The pvc foam is substantially closed cell. The material is completely dry: It carries no impregnants.

When Alfas seal is evenly compressed between two smooth surfaces, it forms a reliable dust and air seal (grades P115 and P145) and an effective weather seal (grades P185, P235, P275 and P335).

Applications construction and allied industries;
Glazing, security glazing (in ds form), secondary glazing, curtain walling, structural glazing, roof lights, cladding and roofing applications, barrier tapes, seals for ductwork in ventilation and air conditioning, suspended ceilings, internal partitions, draught excluding, on site shuttering.

Other industries:
Boat manufacture, ships, railway carriages, aircraft, caravans, motor vehicles, containers and portable buildings, electronics industry, refrigeration (Alfas seal has good thermal and acoustic properties). Alfas seal can be cut into shaped gaskets.

DESCRIPTION:

Composition:
The foam is composed of a polyvinyl chloride paste polymer, plasticised with high quality monomeric polymeric softening agents. An acrylic moisture-resistant self-adhesive layer is added. The adhesive exhibits high strength and good stability under varying atmospheric conditions with good resistance to plasticiser migration and UV degradation. The product is available in six different densities from the lightest grade which is suitable for draught excluding to a heavy duty weather and water seal. A variety of colours are available ( although the standard colours are black or white) as well as widths and thickness to suit most applications.
The self adhesive finish can be applied on one or both faces or alternatively the product can be supplied plain.

Manufacture;

A paste consisting of long chain polymer (k35) monomeric and polymeric plasticisers, generally organometall ic stabiliser, lubricants and fillers is cast onto a moving stainless steel belt and passed through curing ovens. After cooling, the material is passed through a laminating machine which applies a high performance adhesive layer. The material is rolled onto logs and split to the size required.
shape, dimension; thickness of foam are generally available from 1 mm upto 2 mm (see physical data) and care should be taken to specify the appropriate thickness allowing for compression. Any width of roll may be specified from 8 mm upto 950 mm in 1 mm increments. Roll lengths vary according to thickness and grade.
Special roll lengths and colours may be ordered against minimum quantities.

PERFORMANCE:
Deformation figures below illustrate the compressibility of alfas seal.

Table 1

Load applied in kgs/m2	Static load deflection in %grade p235
1	0.6
3	2.6
5	3.9

Heat and fire:
PVC is a halogenated polymer of high molecular weight and as such has inherent flame inherent flame retardent properties. The acrylic adhesive itself is flammable, but since it is in the form of a thin layer which is sandwiched between the substrate and the pvc foam, the rate of flame spread is limited. PVC foams when heated to high temperatures or when burned, may give off chlorine and other halogenated gases. The standard grades of Alfas seal are flame retardent. A specially resistant grade is available as well as a higher temperature grade (subject to minimum quantities).

Biological:
Resistant to attack by fungus, insects or vermin staining; Does not stain or discolour surrounding material such as wood, metal or most plastics.

Chemical:
Care should be taken to varify the chemical compatibility of alfas seal with certain plastics. Our technical department will be pleased to advise in case of doubt.
Alfas seal offers reasonable resistance to dilute acids, alkalis, mineral oils, industrial alcohol and petrol.

Ageing and light:
Ageing in the natural environment causes slight surface degradation over many years and some loss of plasticiser which migrates to the surface and works into adjoining areas or evaporates gradually into the atmosphere.
The change is small and the foam remains supple and active as a sealant over its life span. The adhesive system (dst) incorporates a special barrier which minimises the effect of plasticiser migration. The effects of high humidity are negligible.

Alfas seal has been field tested over long periods in the applications described and has been found to weather well under normal environmental conditions.

Table 2
Physical properties of adhesive systems.

Min. adhesive weight	UNITS g / m2	DSX 50
Min. peel adhesion after 20 mins 180 dg from glass	n / cm	4.0
Dynamic tensile	n/25mm2	80
Adhesion after 24 hrs water immersion ageing resistance	Good

Sitework:

Handling and storage;
No special precautions are necessary in the handling of Alfas seal. Long term storage (upto 12 months) should ideally be interleaved in original packaging in cool, dark conditions. Do not apply excessive loading onto the cartons.

Application:
No special surface preparation or primers are required. Surfaces should be clean, dry and free of grease or lubricants. The product is applied by removing the protective release paper, thus exposing the adhesive surface(s). The seal is positioned and pressure applied to bond. The opposite surface is then brought into contact and fixed to ensure that the correct compression is used. This will consolidate the adhesive bond. A tapered lap joint is suggested at the junction of two rolls, with the angle at which the seal is cut not exceeding 45 dg. The joint maybe adhered using a soft vinyl adhesive. Care must be taken not to stretch the material during installation. Adequate slack must be allowed particularly at joints and where the seal passes around corners.

Table 3

Physical data	Units	Grade p235
Application		heavy duty, weather and water seals.
Recommended compression by	%	30
Availability (thickness) (colour)		2, 3, 4, 5, 6, 8, 10, 12 black / white
Density	kg/m3	220 - 250
Tensile strength din 53571	m pa	0.35
Elongation at break din 53571	%	150
Tear resistance din 53515	kg/cm	2.0
Water absorption (under comp)	%	3
Water vapour permability	g/m2/24 hrs	16.2
Thermal conductivity din 52612	kcal/mh dg c	0.045
Resistance to ageing	(blue scale 5)	good
Operating temperature bs 2571	dg C	-30 / +50
Short periods bs 2571	dg C	-40 / +80