Description SILBIONE MM SERIES 71791 U are silicone rubbers which cure

after addition of a vulcanising agent (chosen as a function of the

production process).

This series includes four products which differ by their hardness

once cured : 40-50-60 and 70 Shore A.

Once processed SILBIONE MM SERIES 71791 U , "Food contact

and biomedical grade" are intended for:

· biomedical applications

· applications requiring a material that is non-toxic under normal

conditions of use and inert to food products.

SILBIONE MM SERIES 71791 U , are elastomers comprising

polymethylvinylsiloxane gums and silica. They heat cure after

addition of an organic peroxide compound. This vulcanisation must

be followed by post curing at 200°C.

Special properties · Easy processing

· Highly transparent

· Excellent mechanical properties, including high tear strength

and a good compromise between tear strength and

compression set

· Very good resistance to oxidising agents (oxygen, ozone, UV)

· Very good behaviour for all sterilisation modes

· Very good release properties

· Chemically inert

Regulations The composition of SILBIONE MM SERIES 71791 U enables them to

be used in conformity with the definitions in the following European and

American regulations.

Food contact:

France : Journal Officiel – Brochure 1227– order dated 25 November

1992.

Germany : BGVV XVA and LIIA.

United States : : US- FDA- CFR 21- part 177. 2600.

Italy : Gazetta Ufficiale – law dated 1973 and addendum.

Moreover, samples of SILBIONE MM SERIES 71791 U, catalysed

with dichloro- 2, 4 benzoyle peroxide, have been subject to

migration tests in accordance with European regulations: Directives

82/ 711/ EEC and 93/ 8 EEC and American regulations: US- FDACFR

21- part 177. 2600.

Regulations Drinking water contact

SILBIONE MM SERIES 71791 U of hardnesses 50 and 60 ShA, have

been successfully proven to be in conformity with German KTZ

regulation part 1.3.13.

Medical devices.

Basic biological studies; cytotoxicity, irritation, sensitisation and

hemocompatibility, required by directive 93/42 CE dated June 14

1993, relative to medical devices and USP Class VI of US, have

been carried out on samples of SILBIONE MM SERIES 71791 U ,

catalysed using dichloro 2,4 benzoyle peroxide.

The summaries of the biological studies are available on request.

In all cases it is the finished article manufacturer’s

responsibility to check conformity with the tests imposed by

the appropriate regulations.

For medical applications, Rhodia Silicones SAS forbids the

commercialisation of these elastomers for the production of

medical devices:

· implanted for more than 29 days

· in contact for more than 29 days with blood and the

mucous membranes (contraception, obstetrics)

· for plastic surgery

Applications SILBIONE MM SERIES 71791 U , once catalysed and processed is

recommended for the manufacture of the following articles:

Those which enter in contact with food such as :

· Tubes for drink distribution, including potable water

· Baby’s bottle tops

· Various technical parts.

· Sections, sleeves, calendered sheets, belts and conveyor belts

Those used in pharmacy such as:

· Tubes and piping for the circulation of liquid or soluble

medicines

· Medicine conveyor belts, etc.

Those used for medical applications such as:

· Tubes and piping for extra-corporal circulation

· Oxygenotherapy tubes

· Self-injectable syringe seals

· Breathing masks

Quality Assurance 1- Manufacture

Rhodia Silicones takes particular care in manufacturing and quality

control in order to guarantee users with the supply of an elastomer

whose quality level is in conformity with the special requirements in

these types of application:

· lack of cross-pollution.

· high level filtration.

· Specific controls.

All of these operations are part of Rhodia Silicones’ quality control

policy, certified to ISO 9001.

Quality Assurance 2- Control

Specific controls are carried out on each batch of SILBIONE MM

SERIES 71791 U to meet the various regulations.

The results are written on the analytical test certificate in addition to

the mechanical characteristics.

SPECIFICATION FOOD GRADE MEDICAL GRADE

ON POST CURED VULCANISED PRODUCT

Identity : IR Spectrum In Conformity m m

Volatile content (%):

(200°C-10g-4h)

0.5 maxi. m

Residual peroxides (%) 0.08 maxi. m

Mineral oils (fluorescence) In Conformity m

ON AQUEOUS EXTRACT

Turbidity (NTU) 4 maxi. m

Alkalinity (ml 0.01 M HCl) 1 maxi. m

Acidity (ml 0.01M NaOH) 1.5 maxi. m

Reducing substances

(ml 0.01 M Na2 SO3)

1 maxi m

ON HEXANE EXTRACT

Hexane soluble (%) 3 maxi m m

Phenyl compounds (DO/UV) 0.4 maxi. m

Heavy metals (ppm) (other than

aqueous extract)

10 maxi m

Processing methods The choice of vulcanising agent (peroxide) to add to the SILBIONE

MM SERIES 71791 U depends on the processing method and the

conformity with various “Food contact grade” regulations.

The various processing methods are summarised in the table

below:

SILBIONE

MM SERIES 71791 U

Dichloro- 2, 4 benzoyle

Peroxide at 50 %

(E)

Dicumyl Peroxide

at 95 %

(D)

2, 5 dimethyl-

2, 5- di (tertio- butylperoxy)

hexane at 72 %

(L)

compression

Moulding injection

0.6 parts per 100

master batch

0.6 parts per 100

master batch

hot air vulcanisation 0.9 to 1.25 parts per 100

master batch

6 to

12 bar

0.6 parts per 100

Extrusion pressurised master batch

steam

vulcanisation

12 to

20 bar

0.6 parts per 100

master batch

Calandering hot air vulcanisation

0.9 to 1.25 parts per 100

master batch

Characteristics 1- Physical properties

Type (according to AFNOR T 40002)....... .................................MVQ

Hardness Specific gravity at 25 ° C, approx.

40 ShA 1.10

50 ShA 1.13

60 ShA 1.15

70 ShA 1.18

Characteristics Natural colour......................... ........................................Transparent

2- Mechanical properties

Below we give an example of the characteristics obtained using

dichloro- 2, 4 benzoyle peroxide (at 50%) as a vulcanising agent.

Measurements are made on a 2 mm thick moulded sheet, cured for

8 min at 115°C and post cured for 4 hours at 200°C.

SILBIONE MM SERIES 71791 U 71 791/40 U 71 791/50 U 71 791/60 U 71 791/70 U

Peroxide dose in parts per 100 of master batch 0.9 1 1.25 1.25

ShA hardness , points, approx

(Standard ASTM D 2240)

43 53 62 72

Tensile strength, MPa, approx,

(Standard AFNOR NF T 46- 002)

9.0 9.5 10 9.5

Elongation at break, %, approx,

(Standard AFNOR NF T 46- 002)

600 640 500 410

Tear strength, kN/m, approx,

(Standard ASTM D 624 A)

31 38 38 34

Compression set ( 22h/ 177°C/ 25%), %, approx,

(Standard ASTM D 395 B)

27 34 40 40

Rebound resilience (thickness 8 mm), %, approx,

(Standard DIN 53 512)

50 45 42 37

Linear shrinkage %, approx, 3.5 3.7 3.7 4.0

SILBIONE MM SERIES 71791 U must be post cured at 200°C

after vulcanisation (it is recommended not to exceed this

temperature).

Post curing is essential in order to :

· Ensure conformity with the legislation and regulations currently

in force

· Stabilise the mechanical properties of the elastomer as well as

its dimensions

· Ensure the heat stability of the elastomer

· Improve its chemical resistance, especially with respect to

solvents, fats and steam

Processing 1- Adding peroxide to SILBIONE MM SERIES 71791 U

This operation is performed on a two-roll mixing mill.

Operating procedure :

à Check that the equipment is scrupulously clean in order to avoid

including impurities that would detract from the quality and properties of

the SILBIONE MASTER BATCH.

à Plasticise the SILBIONE MASTER BATCH.

Use of a back / front roller speed ratio of between 1.25 and 1.4 ensures

sufficient friction to give good plasticising.

à Add the peroxide, then mix by cutting and crossing.

à Cool the cylinders throughout the operation in order to maintain the

SILBIONE MASTER BATCH at a temperature below 30°C;

In the case of catalysis using crystalised dicumyl peroxide, after

dispersion it is recommended to heat the elastomer to 50°C to ensure the

fusion of the peroxide, then to cool to 30° once fully incorporated.

2- Processing

SILBIONE MM SERIES 71791 U obtained in this way can be

processed using all conventional methods in the rubber processing

industry used for traditional materials.

Processing In this way, using SILBIONE MASTER BATCH plasticised on a

two-roll mixing mill, we could:

à Either roll a sheet to the required thickness from which we will cut

preforms for moulding.

à or cut bands that will be used for example to feed an injection press or

to prepare sheets for calendering.

3- Vulcanisation and post curing

Vulcanisation of SILBIONE MM SERIES 71791 U is carried out at

temperatures according to the type of peroxide used.

Once cured we remind you that SILBIONE MM SERIES 71791 U

must be post cured at 200°C in forced air ovens with protected

heating elements.

The post cure duration depends on the thickness of the parts

obtained (moulded, extruded or calendered).

Post curing gives the elastomer its optimum characteristics and ensures

its conformity with the requirements of the regulations currently in force.

Important comments :

Post curing at a temperature above 200°C or any accidental increase in

temperature (e.g. to around 250-300°C) can damage parts causing

stiffening, cracking or formation of a surface glaze. It is therefore

important to use good temperature control together with forced air

ventilation.

Non-ventilated ovens or those with insufficient ventilation can cause

"reversion" to occur : a reduction in hardness due to the onset of

depolymerisation.

Important notice RHODIA SILICONES SAS guarantees the properties given for

SILBIONE MM SERIES 71791 U .

However, our company cannot guarantee the behaviour of this master

batch and the application that is made of it by the user, since it has no

control over the conditions of application nor the process under which a

study has been conducted.

Packaging SILBIONE MM SERIES 71791 U are available in 25 kg reinforced

cardboard cartons. Each master batch is enclosed in a release

coated sheet.

Storage and

shelf life

SILBIONE MM SERIES 71791 U may be stored in its original

unopened packaging at a temperature below +40°C for up to 18

months from the date of manufacture marked clearly on the

packaging.

Past this date, Rhodia Silicones no longer guarantees that the

product meets the sales specifications.When kept in its original

unopened packaging,

According to the hardness, it is recommended to slightly refreshen

SILBIONE MM SERIES 71791 U before using.

Comment : Prolonged storage beyond the recommended expiry date

generally means a reduction in hardness and an increase in refreshening

time

Safety Please refer to the Safety Data Sheets for SILBIONE MM SERIES

71791 U .

Warning to users The information contained in this document is given in good faith

based on our current knowledge. It is only an indication and is in no

way binding, particularly as regards infringement of or prejudice to

third party rights through the use of our products.

RHODIA SILICONES GUARANTEES THAT ITS PRODUCTS

COMPLY WITH ITS SALES SPECIFICATIONS.

This information must on no account be used as a substitute for

necessary prior tests which alone can ensure that a product is

suitable for a given use.

Users are responsible for ensuring compliance with local legislation

and for obtaining the necessary certifications and authorisations.

Users are requested to check that they are in possession of the

latest version of this document and RHODIA SILICONES is at their

disposal to supply any additional information.