ISO 14949:2001
(Main)Implants for surgery — Two-part addition-cure silicone elastomers
Implants for surgery — Two-part addition-cure silicone elastomers
This International Standard specifies the characteristics of, and corresponding test methods for, the two-part addition-cure high consistency or liquid silicone elastomer for use in the manufacture (partially or totally) of surgical implants.
Implants chirurgicaux — Élastomères de silicone à deux composants à réticulation par réaction d'addition
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Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 14949
First edition
2001-10-15
Implants for surgery — Two-part addition-
cure silicone elastomers
Implants chirurgicaux — Élastomères de silicone à deux composants à
réticulation par réaction d'addition
Reference number
ISO 14949:2001(E)
©
ISO 2001
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ISO 14949:2001(E)
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ISO 14949:2001(E)
Contents Page
Foreword.iv
Introduction.v
1 Scope .1
2 Normative references.1
3 Terms and definitions .1
4 Formulation .4
4.1 Composition.4
4.2 Raw materials assessment.4
5 Biocompatibility.5
6 Characterization and testing .5
6.1 Test slab preparation .5
6.2 Identification .5
6.3 Purity testing.5
6.4 Cure rate .6
6.5 Physicomechanical properties and characterization .7
7 Documentation.7
7.1 Data sheet.7
7.2 Certificate of analysis.7
Annex A (normative) Determination of substances soluble in hexane .8
Annex B (normative) Determination of volatile matter .12
Bibliography.14
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ISO 14949:2001(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO
member bodies). The work of preparing International Standards is normally carried out through ISO technical
committees. Each member body interested in a subject for which a technical committee has been established has
the right to be represented on that committee. International organizations, governmental and non-governmental, in
liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical
Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3.
Draft International Standards adopted by the technical committees are circulated to the member bodies for voting.
Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this International Standard may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights.
International Standard ISO 14949 was prepared by Technical Committee ISO/TC 150, Implants for surgery,
Subcommittee SC 1, Materials.
Annexes A and B form a normative part of this International Standard.
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ISO 14949:2001(E)
Introduction
Silicones are commercially available in a variety of physical forms and formulations. Silicone-cure products often
employ cure mechanisms that utilize metals, free radicals and/or atmospheric moisture. This International Standard
was undertaken to describe a subset of silicones with a successful history of use in implant applications; namely,
those utilizing two-part addition-cure (platinum-based) chemistry. It was developed in response to a need to
standardize the raw materials, formulation, processing, characterization testing and documentation of two-part
addition-cure silicone elastomers targeted as implants for surgery.
Two-part addition-cure silicone elastomer is a thermoset elastomer and is commercialized as a two-part (non-
crosslinked) product. The two parts should be thoroughly mixed in a fixed ratio before shaping by extrusion, press-
or injection-moulding and crosslinking at elevated temperatures.
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INTERNATIONAL STANDARD ISO 14949:2001(E)
Implants for surgery — Two-part addition-cure silicone elastomers
1 Scope
This International Standard specifies the characteristics of, and corresponding test methods for, the two-part
addition-cure high consistency or liquid silicone elastomer for use in the manufacture (partially or totally) of surgical
implants.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of
this International Standard. For dated references, subsequent amendments to, or revisions of, any of these
publications do not apply. However, parties to agreements based on this International Standard are encouraged to
investigate the possibility of applying the most recent editions of the normative documents indicated below. For
undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC
maintain registers of currently valid International Standards.
ISO 34-1:1994, Rubber, vulcanized or thermoplastic — Determination of tear strength — Part 1: Trouser, angle and
crescent test pieces
ISO 48:1994, Rubber, vulcanized or thermoplastic — Determination of hardness (hardness between 10 IRHD and
100 IRHD)
ISO 527-2:1993, Plastics — Determination of tensile properties — Part 2: Test conditions for moulding and
extrusion plastics
ISO 3417:1991, Rubber — Measurement of vulcanization characteristics with the oscillating disc curemeter
ISO 6502:1999, Rubber — Guide to the use of curemeters
ISO 10993-1:1997, Biological evaluation of medical devices — Part 1: Evaluation and testing
ISO 10993-5:1999, Biological evaluation of medical devices — Part 5: Tests for in vitro cytotoxicity
3 Terms and definitions
For the purposes of this International Standard, the following terms and definitions apply.
3.1
catalyst
organometallic complex, typically containing platinum substituted by ligands made of any suitable combination of
the elements carbon, hydrogen, oxygen, chlorine or silicon (with the exclusion of aromatic rings), which initiates a
chemical reaction between a polymer and crosslinking agent
NOTE The catalyst may be dispersed in a silicone oligomer, polymer or mixture of these, such as
RMe SiO(SiMe O) (SiMeR¢O) SiMe R where R and R¢ are methyl or vinyl groups.
2 2 x y 2
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ISO 14949:2001(E)
3.2
crosslinking agent
monomer, polymer, silicate or any combination of these, typically of the structure
R≤Me SiO(SiMe O) (SiRMeO) SiMe R≤ where R≤ is typically a methyl group or hydrogen, that on curing provides
2 2 x y 2
a crosswise connection to parallel polymer chains
NOTE Excess SiH is recommended (not required) before curing to ensure that the cure is total and that no residual Si-vinyl
reactive entities exist, thus providing better elastomer stability.
3.3
filler
reinforcing agent
〈for the purposes of this International Standard〉 silicate or high purity amorphous silica
NOTE 1 Such agents are commercially known as fumed or precipitated silica.
NOTE 2 Silica can be treated with silylating agents, for example, those of the formula Me SiX or Me SiX where X is a
3 2 2
hydrolysable group, or polysiloxane oligomer of the formula HOMe SiO(SiMe O) (SiMeRO) SiMe OH where R is a methyl or a
2 2 p q 2
vinyl group.
NOTE 3 Agents that impart radiopacity to the elastomer (e.g. BaSO ) may have reinforcing properties.
4
3.4
inhibitor
compound or material that has the effect of slowing down or stopping a chemical reaction such as crosslinking
3.5
lot
batch
defined quantity of material manufactured in a single or multi-step process such that the material obtained can be
considered as homogeneous
NOTE in the case of a continuous process, the term corresponds to a defined fraction of the production, characterized by
its intended homogeneity.
3.6
manufacturer
company who manufactures the final medical device in question
3.7
raw materials
materials from which two-part addition-cure silicone elastomer is manufactured
3.8
silicone elastomer
synthetic rubber obtained by the crosslinking of silicone polymer chains essentially made of repeat siloxane units
EXAMPLE
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ISO 14949:2001(E)
3.9
silicone polymer
any polymer or combination of polymers of medium or high molecular mass of the structure
RMe SiO(SiMe O) (SiMeR¢O) SiMe R, where R is typically a methyl, vinyl or hydroxyl group but might also be a
2 2 x y 2
fluoro, phenyl or other group and where R¢ is typically a methyl or vinyl group but might also be a fluoro, phenyl or
other group
EXAMPLE 1
EXAMPLE 2
EXAMPLE 3
both R and R¢ are methyl, phenyl, fluoro or other suitable organic groups.
NOTE The definition of the polymer and its substituted groups is taken very broadly, as it is not the function of this
International Standard to limit the number or the type of substituent groups present; however, for the purposes of this
International Standard the definition only relates to materials with available preclinical biocompatibility data (see clause 5) and a
well-established history of safe international use in implant applications.
3.10
supplier
company who manufactures and/or supplies the two-part silicone elastomer used for the production of the medical
device in question
3.11
treating agent
monomer, oligomer or polymer used to coat the outer surface of silica to reduce the reactivity of the silica
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ISO 14949:2001(E)
3.12
two-part addition-cure silicone elastomer
elastomer formed by crosslinking silicone polymer chains via an addition reaction between the vinyl functional
groups of a vinyl silicone polymer and the silicon hydride of a crosslinking agent containing SiH functions
NOTE The reaction requires the presence of a catalyst, usually an organometallic complex of platinum.
EXAMPLE
4 Formulation
4.1 Composition
The defined raw materials shall be used in a formulation as defined in Table 1.
Table 1 — General formulation for two-part addition-cure silicone elastomers
Percentage range
Compound
(% mass fraction)
Silicone polymer 60 to 80
Reinforcing agent less than 40
Crosslinking agent 1 to 5
Catalyst
< 0,5
Inhibitor
< 1,0
4.2 Raw materials assessment
Both during product development and on an audit basis (at least once a year or every tenth production lot), the
supplier of the two-part addition-cure elastomer shall assess the raw materials (see 3.8) as follows.
a) Structure and functionality of polymer
The structure and functionality of the polymer(s) used shall be determined by a suitable method such as
nuclear magnetic resonance spectroscopic analysis (see [2] for further information).
b) Purity of silica
The purity of the silica used shall be assessed by elemental analysis or any other suitable method, and the
result should be expressed as (mg Si obtained/theoretical mass) ¥ 100 = % mass fraction Si.
c) Structure and purity of treating agent(s)
The structure and purity of the treating agent(s) used shall be determined by a suitable method such as
infrared spectroscopy (see [2] for further information).
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ISO 14949:2001(E)
d) Structure of the crosslinking agent(s)
The structure of the crosslinking agent(s) used shall be determined by a suitable method such as infrared
spectroscopy (see [2] for further information).
e) Purity of the inhibitor
The purity of the inhibitor used shall be determined based on an appropriate analysis and shall be greater than
95 % mass fraction (see [2] for further information).
f) Structure of the inhibitor
The structure of the inhibitor used shall be determined by a suitable method such as infrared spectroscopy
(see [2] for further information).
5 Biocompatibility
The biological and physical properties of the cured silicone elastomer depend largely on the formulation as
contained in the two-part starting material. Processing conditions to produce silicone parts (extrusion or molding)
can also impact biological and physical properties. The validation and consistency of production should be part of
the quality system of the supplier. In order to ensure c
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