Silicone rubber for mould making

POLASTOSIL® and GUMOSIL® are two-component silicone rubbers which cure at room temperature in a polycondensation and polyaddition systems after addition of liquid catalyst. Silicone moulding rubber finds many applications across a wide range of industries using various casting mediums. Main areas of application:

• decorations, stuccowork: castings, coiling roses, figurines, decorative candles, statuettes,

• renovation of architectural monuments: making moulds for monuments, archaeological fossils, etc.,

• ceramics: standards and moulds for artistic, home-based and industrial making of ceramic and porcelain products,

• artistic products: sculptures, masks, special decorative elements, figurines, bas-reliefs,

• technology: prototypes and components for leak tests and corrosivity checking, making moulds for technical and industrial applications (e.g. automotive components, audio-video equipment, household products),

• building industry: facade tiles, fireplaces imitating natural stone, stucco, garden structures such as e.g. ornamental garden ponds, fountains, statuettes, etc.,

• pad printing: making of pads,

• shoe making: making moulds for shoe soles, production of artificial leather,

• metal casting: jewellery, decorative products,

• prosthetics.

Properties of RTV-2 silicone rubbers Silicone rubbers are characterized by large range of hardness and elasticity, high tensile and tear strength, high chemical and thermal resistance, low linear shrinkage and excellent reproduction. Working temperature of two-component rubber (RTV-2) is within the temperature range from -50° C to 180° C. Our offer include also silicone rubber with higher temperature resistance (up to 300 ° C) under the trade name Gumosil ® T.

The system of crosslinking conditions the differences between the rubbers e.g. the rubbers which undergo condensation type crosslinking are very insensitive to (resistant to contamination); their vulcanisation time can be only slightly shortened by increasing the temperature. On the other hand, the additive rubbers show considerable increase of vulcanisation rate at an increased temperature. However, the drawback of the additive rubbers is that they are very sensitive to contamination; there is a possibility of „intoxicating” the catalyst by contact with such compounds as: amines, amine compounds, polyurethane, epoxide resins, sulphur, compounds containing sulphur – natural and synthetic rubber.

Silicone rubbers are physiologically neutral. They have excellent resistance to UV radiation, ozone and atmospheric factors. Due to their light colour, possibly their transparency, they are easily dyed to any colour. They also have very good gas permeability and are characterized by good electrical properties. Electrical resistance is about 10¹⁵ Ω cm; resistance to breakdown is approximately 20 kV for 1 mm plate. It is possible to obtain rubbers having a hardness from 20 to 65° ShA and a density from 1.1 to 1.25 g/cm³.   In comparison to organic rubber, the silicone rubber shows very small viscosity in a room temperature. It is characterized by good mechanical parameters:

• tensile strength: from 1 to 8MPa

• elongation at break: from 100 to 650%

• linear shrinkage from 0.1 to 2%

The last of the above-mentioned parameters is of particular importance when negatives of very small parts are made. Lower linear contraction enables more precise representation of a given part. Silicone rubber is in increasing demand in those areas of application where good dampening characteristics and a very high rubber compressibility ratio are required.In electrical engineering the rubber is used as a noise dampening element between winding and a core in some types of transformers.

Many synthetics and natural materials can be formed in rubber moulds:

• natural or synthetic wax,

• resins: filled polyesters, stiff or semi-stiff polyurethanes, epoxides,

• elastomers: silicone rubbers, polyurethanes, etc.,

• concrete with fillers, ornamental plaster works,

• metal of low melting temperature,

• gypsum.

The Company also produce rubbers that are used for protecting electric and electronic systems (including such systems installed in small size motors) as well as transistor systems against impact of external factors such as: moisture, dust, precipitation, etc. These rubbers are marketed under POLASTOSIL® M-60, POLASTOSIL® M-2000 and POLSIL® MV AB, POLSIL® MV AB/S trade names. RTV-2 silicone rubbers can be used to make mouldings on vertical surfaces by employing thixotroping agent: Gumosil ® PC 12– for polycondensation silicone rubber Gumosil ® WW, Gumosil ® K, Gumosil ® M, Gumosil ® S. Gumosil ®AD/C for polyaddition silicone rubber Gumosil ® AD-1, Gumosil ® AD-4.