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cz Product Data Sheet

Lučební závody a. s. Kolín

Pražská 54, 280 02 Kolín, Czech Republic
 +420 321 741 546-7  odbyt@lucebni.cz

LUKOPREN N 8100 and N 8200

High-strength two-component silicone rubber products
Silicone moulding and potting materials Lukopren Lukopren N 8100
N 8100 and N 8200 are two-component rubbers
The silicone rubber paste of enhanced viscosity suita-
that are cured by condensation. On mixing rubber ble for the manufacturing of heavy-duty moulds and
paste and Lukopren Catalyst 8A at regular parts requiring very high mechanical and chemical re-
temperature only several hours are needed for the sistance. It is more difficult to process.
mixture to become cured throughout its entire mass Lukopren N
and to create silicone rubber with limited adhesion 8100 has the
to smooth non-porous surfaces. highest tear re-
sistance, elon-
Use gation and
chemical re-
 production of complicated, perfectly separating,
sistance from
flexible moulds requiring high mechanical and
all silicone rub-
chemical resistance
bers Luko-
 moulds for the casting of synthetic resins (epoxy,
pren N.
polyurethane, polyester, acrylic), artificial stone,
concrete, gypsum and wax
 production of flexible, high mechanical and chem-
ical resistance rubber parts, seals and washers
made to measure, separation layers Lukopren N 8200
 encapsulation of electrical components The easy-to-process rubber paste with excellent fluidity.
 as anti-vibration and damping materials Compared to Lukopren N 8100, Lukopren N
8200 exhibits the lower viscosity and thus the better
Properties of rubber paste fluidity of the
 good flowability, self-leveling ability paste, its easier
 accurate copying of fine details
workability and
faster disappea-
 curing at normal temperatures
rance of air bub-
 neutral, non-corrosive system without releasing
bles.
heat during vulcanization
 possibility of layering and combining both types of
rubber with a perfect connection

Properties of silicone rubber Compared to common low-strength rubber, Luko-

pren N 8100 and Lukopren N 8200exhibit espe-
 resistance against weather conditions, sunlight and cially higher elongation, higher tear strength (tear re-
ozone sistance), higher resistance to organic casting resins,
 limited adhesion to smooth non-porous sub- longer service life of manufactured moulds.
strate
 ability to separate from a number of non-porous
surfaces, including cast resins, easy demoulding
 thermal resistance in wide temperature range
Lukopren Katalyzátor (Catalyst) 8A
 resistance against an electric arch and the co- Crosslinking agent for two-component silicone rubbers
rona, effect even under heat stress Lukopren N 8100 and N 8200 (clear to yellowish
liquid).
 excellent electroinsulating properties
 vapor permeability higher than other rubbers re-
sistance against mild acids and bases, polar sol-
vents, and most salts
 swell in hydrocarbons - a reversible process

Lukopren N 8100 and N 8200

www.lucebni.cz Produst Data Sheet

Technical parameters of rubber paste and catalyst

Lukopren N 8100 N 8200 Katalyzátor 8A

Colour green (RAL 6021) yellow (RAL 1016) colourless to yellowish
Viscosity at 20 °C (mPa.s)
50 000 19 000 13.5
(ČSN 640349)
Density (g/cm3) 1.115 1.110 1.005

Catalyst dosing and vulcanization characteristics at 23 ± 2 °C, 50 ± 5 % RH

Lukopren N 8100 N 8200 In the case of low humidity

(below 30%), the vulcaniza-
Catalyst 8A tion time increases, espe-
3 3 4
wt. % (g/100g) cially with thick layers, the
surface of the vulcanizate
Minimum processing time may stick for a longer time
50 70 45
(min) than usual. Therefore, it is
Demoulding after* mini- advisable to increase the hu-
24 48 24 midity of the air, for exam-
mum after (hours)
ple, with steam or by apply-
Working temperature (°C) +5 až +40 ing a wet cloth to the mould.
*mould / casting wall thickness up to 6 mm

Vulcanizate parameters vulcanization 48 hours under standard conditions (23±2 °C, 50 ±5 % RH)
Lukopren N N 8100 N 8200
Tensile strength (MPa) The time to reach the final
2.2 1.8 parameters depends on
(ČSN ISO 37)
the thickness of the layer,
Structural strength (kN.m1) 9.0 7.0 it is partly influenced by
(ČSN 62 1459 type 2) the humidity of the envi-
Elasticity (%) ronment. For thick-walled
350 270 castings / layers with a
(ČSN ISO 37)
Hardness (°ShA) thickness of more than 1
21 19 - 23 cm, the demoulding time
(ČSN ISO 48-4)
/ time of reaching the fi-
Linear shrinkage nal parameters will be
0.15 0.15
max. (%) more than 48 hours.
Thermal resistance (°C) -50/+180
In the case of a rapid clo-
Coefficient of thermal con- sure of the encapsulated
0.23 – 0.29
ductivity (W/m.K) space, the time to reach
Dielectric strength (kV/mm) min. 13 the final parameters is fur-
Resistivity ( . cm) ther extended.
min. 1012
(at frequency 1 kHz)

Processing procedure
 First, the entire content must be homogenized. The  The mixture is applied by pouring its thin stream or
necessary amount of the homogenized paste is then by painting with a brush.
weighed into an appropriate, ideally plastic container  The processing of both rubber pastes is very diffe-
and mixed with a prescribed amount of Lukopren rent from each other, given their different viscosities.
Catalyst 8A. A catalyst must be mixed-in carefully be- Lukopren N 8100 is difficult to process due to its
cause of the marked difference between both compo- high viscosity, and the escape of bubbles is also di-
nents’ viscosities. The mixture is thoroughly stirred with fficult. Its difficult workability is compensated by the ex-
the flat spatula, especially on the bottom and in the cellent properties of the vulcanizate. Lukopren N
corners of the container in order to prevent the mixing 8200 has a lower viscosity and thus better flowability
of air into the material (this is why catalyst must not be of the paste, easier mixing with the catalyst and faster
stirred with a propeller agitator by means of an electri- escape of air bubbles.
cal drilling machine).

Lukopren N 8100 and N 8200

www. lucebni.cz Product Data Sheet
 The mixture can be evacuated to remove air Behavior to the substrate
bubbles (due to the expansion of bubbles, a larger  Lukopren N rubbers have a very low adhesion
container must be chosen). Without the use of evac- to other non-porous materials such as glass,
uation, the catalyzed mass can be deaerated or ap- enamel, steel, aluminum after vulcanization. To im-
plied in thin layers for a few minutes before appli- prove the adhesion, the bonded surfaces must be
cation and always wait for the bubbles to leave, or pre-treated with special bonding agents, so-called
remove them with a sharp tip. Lukopren Primer A or Lukopren Primer N. It is
 The workability time of the homogenized paste
applied in a thin layer on the degreased and rough-
with the catalyst depends on the metered amount of ened substrate. After drying (approx. 20 minutes),
catalyst, but at least 45 minutes (depending on the the rubber can be poured in.
type of rubber and the amount of catalyst). Worka-  When applying a new layer to an already vul-
bility time is defined as the time from mixing the cat- canized rubber layer, a primer is not necessary, the
alyst to the moment of visible increase in consistency layers adhere very well to each other (if the original
and loss of self-leveling capabilities. Under normal surface is not dirty, greased).
conditions, the catalyzed rubber vulcanizes evenly  Bonding of cracked silicone rubber from Luko-
throughout the mass. pren N or its gluing to the substrate is performed
with one-component silicone sealant Lukopren S
Dosing of small amounts of catalyst 6410, S 8280 (degrease contact surfaces before-
 Due to the density of the catalyst, small quanti- hand).
ties can be dosed in grams as quantities in milliliters
(a plastic pipette is included in the carton). The nec- Separation
essary catalyst aspiration is performed by squeezing  When manufacturing moulds, it is advised to
the balloon at the top of the pipette. After use, the coat the surface with the Lukopren Separator
pipette should be flushed immediately with Luko- (separating agent), which creates a film with good
pren Odmašťovač (Degreaser) (alcohol, ace- separation properties after drying. It can be washed
tone or benzine). away with water. Oil, petroleum jelly, etc. are not
Amounts less than 0.5 ml can be dispensed with the suitable for separation because they disturb silicone
number of drops: rubber from the very beginning of vulcanization.
Volume (ml) 0.1 0.2 0.3  The Lukopren Paraffin Separator is intended
Number of drops 4–5 9 13 for the separation of silicone rubber (eg contact sur-
faces of silicone multipart moulds) or other water-
repellent material. The separation must be carried
It is not recommended:
out very consistently and always wait for the solvent
× blending with other Lukopren N or with other ad- to evaporate completely. When separating a thin
ditives e.g. to obtain a lower viscosity (excluding mix- layer of vulcanizate, the action of the solvent from
ing N 8100 and N 8200).
the separator can cause swelling, which disappears
× to heat the rubber during curing (increased cre-
after its evaporation (approx. 1 hour).
ation of bubbles due to the production of gaseous
products, devaluation of the catalyst).
Colouring of rubber pastes
× to use a greater amount of added catalyst. This
accelerates curing and shortens the processing time Lukopren N 8100 and N 8200 rubber pastes
but it causes greater occurrence of undesirable lin- can only be coloured (with organic and inorganic
ear shrinking and prevents the air bubbles from pigments) to certain colour shades due to the colour
leaving the poured surfaces. pigments already present. They are best applied in
× to use a smaller amount of added catalyst as this the form of pigment pastes in an amount of 1-5 wt.
leaves the rubber remains soft or even gluey. Com- % to rubber paste before catalyst addition - can be
plete curing does not take place, required proper- purchased in white, black, yellow, blue, green and
ties are not obtained and the primary model can be brick.
damaged permanently.
× repaint with paints (the vulcanizate cannot be
overpainted with paints).
Cleaning
 Unvulcanized rubber paste can be wiped off
(cloth, paper towel) and the residue cleaned with
Tempering of moulds and castings
Lukopren Odmašťovač (Degreaser), acetone,
 This step is not necessary in many cases, but is petrol or thinners (type toluene, xylene). Already
recommended to achieve volume stabilization of hardened rubber (vulcanizate) has low adhesion to
the mould and when using the vulcanizate at higher the substrate, can be easily removed by peeling.
temperatures. It is performed in an oven with air ex-
change by gradually increasing the temperature up
to 150 °C and leaving it in the oven for at least 30
minutes.

Lukopren N 8100 and N 8200

www. lucebni.cz Product Data Sheet
Manufacturing of resilient moulds Two-part layered mould with the backing case
 With more complex models with uneven thickness
Preparation of models
and a difficult relief, it is advised to create a 'layered'
 A model can be made of wood, metal, plastics,
mould. The model is positioned up to the chosen
ceramics, gypsum, wax, paper, marble, stone, or clay.
parting line in a plastiline or clay in the frame or box
Its surface must be free of any flaws unless they are to
(positioning pins are defining for easy assembly of
be intentionally reproduced. The surface of models of
mould and case parts too). Three to five coatings of
porous materials must be sealed with lacquer coats.
rubber are gradually applied after a previous rubber
Good separation is achieved when the surface of the
coating has cured properly. The optimal thickness of
model is painted with a thin layer (with a cloth) of Lu-
such a mould is 2 - 3 mm. If this is the case, a gypsum,
kopren Separator. Separation of models made of
concrete or polyurethane backing case has to be
silicone resin or other rainproof materials is achieved
created to reinforce the mould. Once the first half of
with Lukopren Paraffin Separator.
the mould and backing case have hardened, the
auxiliary box is removed. The model embedded in the
Mould casting - simple model (plastic pictures, first part mould and case is placed in a new frame.
coins, emblems, ornaments)  The second exposed of model is poured according
 A model is placed into an auxiliary container or a
to the same procedure as the first part. Rubber-rubber
box made of plates. Prepared rubber paste is poured bonds are separated by means of Lukopren
slowly and carefully so as to avoid the creation of air
Paraffin Separator.
bubbles and to break the bubbles that have been
formed during catalyst mixing. The mechanical
Time demoulding
resistance of the mould can be enhanced with meshed
 Recommendation: the mould should be removed
fabrics such as gauze, silk, burlap, or nylon netting.
and the model should be taken out no sooner than
The thickness of the walls of models that are about 30
after 24 - 48 completed hours of cure, for thicker
cm big should not exceed 1 cm. The wall thickness of
forms even after a longer period of time.
smaller models should not be greater than 5 - 8 mm.
 The subsequent casting in the mould is recom-
mended to perform after 48 hours.
Mould casting - three-dimensional model
 With the simpler type of three-dimensional models
Packaging
(i.e. those even thickness in all three dimensions), a
 Lukopren N 8100 and N 8200: carton (900 g
two or multipart mould can be made only of silicon
paste + 40 g Lukopren Catalyst 8A + pipette), pails 5
rubber. The first half of the model is poured with the
kg (catalyst not included).
rubber paste – the parting line creates a suitable lon-
Lukopren Catalyst 8A: bottle 40 g and 200 g
gitudinal section model.
 The second mould part is done, when the first half
is cured. Rubber-rubber bonds are separated by Storage
 Lukopren N 8100 and N 8200 - 9 months from
means of Lukopren Paraffin Separator.
a manufacturing date in the original packaging. Pro-
ducts in plastic packaging can be stored in a maximum
Stripping mould – small and simple model
of 2 layers. Before application stir properly!
 Lukopren N 8100 also facilitates the preparation
 Lukopren Catalyst 8A - 12 months from a
of simple “stripping” moulds.
manufacturing date in the original packaging, must be
 These are thin-layer moulds only for small simple
kept tightly closed to avoid contact of the product with
models, where 3 to 5 layers of rubber are gradually
humidity.
applied with a brush (always after the previous layer
has hardened) without the use of textile reinforcement.
It is necessary to remember the infusion hole of the Health protection
mould (often it is the base of the model). After perfect  Lukopren N 8100 and Lukopren N 8200: Safety
vulcanization, the mould simply removes from the data sheets are available on request.
model. For subsequent casting, it is usually necessary  Lukopren Catalyst 8A is classified as a dangerous
to create auxiliary beds. chemical agent. Prior application read its label and
safety data sheet carefully and follow the prescribed
instructions.

This brochure includes information that is not binding and that is provided for the customer's information only. The described
types of applications are not exhaustive. Should you have any concerns or doubts contact the Department of Sales and
Technical Services of Lučební závody a. s. Kolín, e-mail: ots@lucebni.cz, www.lucebni.cz 2/2023