ASTM F2468-05

Standard Classification for Specifying Silicone Adhesives and Sealants for Transportation Applications

SCOPE
1.1 This classification covers silicone adhesives and sealants intended for but not limited to sealing and retaining metallic and nonmetallic component assemblies in transportation applications. The materials cure to an elastomeric state by their specified cure system and mechanism.Note 1
The classification system may serve many of the needs of industries using silicone materials. This classification is subject to revision, as the need requires; therefore, the latest revision should always be used.
1.2 This classification is intended to be a means of classifying silicone materials. It is not intended for engineering design purposes.
1.3 It is not the intent of this classification to include pressure-sensitive or hot-melt adhesives.
1.4 In all cases in which the provisions of this classification system would conflict with the referenced ASTM standard for a particular method, the latter shall take precedence.
1.5 &si-value;
The following safety hazards caveat pertains only to the test methods portion, Section , of this classification. This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 28-Feb-2005
• ICS: 55.040 - Packaging materials and accessories
• ICS: 71.100.55 - Silicones
• Technical Committee: F03 - Gaskets
• Drafting Committee: F03.30 - Classification

Relations

• Replaced By: ASTM F2468-05(2011) - Standard Classification for Specifying Silicone Adhesives and Sealants for Transportation Applications
• Effective Date: 01-May-2011
• Referred By: ASTM F2523-13(2020) - Standard Practice for Blowout Resistance of Room-Temperature Vulcanized Elastomers
• Effective Date: 01-Mar-2005

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: F2468 – 05
Standard Classification for
Specifying Silicone Adhesives and Sealants for
Transportation Applications
This standard is issued under the fixed designation F2468; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope Dielectric Strength of Solid Electrical Insulating Materials
at Commercial Power Frequencies
1.1 This classification covers silicone adhesives and seal-
D150 Test Methods for AC Loss Characteristics and Per-
ants intended for but not limited to sealing and retaining
mittivity (Dielectric Constant) of Solid Electrical Insula-
metallic and nonmetallic component assemblies in transporta-
tion
tion applications. The materials cure to an elastomeric state by
D257 Test Methods for DC Resistance or Conductance of
their specified cure system and mechanism.
Insulating Materials
NOTE 1—The classification system may serve many of the needs of
D412 Test Methods for Vulcanized Rubber and Thermo-
industries using silicone materials. This classification is subject to
plastic Elastomers—Tension
revision, as the need requires; therefore, the latest revision should always
D471 Test Method for Rubber Property—Effect of Liquids
be used.
D573 Test Method for Rubber—Deterioration in an Air
1.2 This classification is intended to be a means of classi-
Oven
fying silicone materials. It is not intended for engineering
D618 Practice for Conditioning Plastics for Testing
design purposes.
D624 Test Method for Tear Strength of Conventional Vul-
1.3 It is not the intent of this classification to include
canized Rubber and Thermoplastic Elastomers
pressure-sensitive or hot-melt adhesives.
D792 Test Methods for Density and Specific Gravity (Rela-
1.4 In all cases in which the provisions of this classification
tive Density) of Plastics by Displacement
system would conflict with the referenced ASTM standard for
D907 Terminology of Adhesives
a particular method, the latter shall take precedence.
D1002 Test Method forApparent Shear Strength of Single-
1.5 The values stated in SI units are to be regarded as
Lap-Joint Adhesively Bonded Metal Specimens by Ten-
standard. No other units of measurement are included in this
sion Loading (Metal-to-Metal)
standard.
D1053 Test Methods for Rubber Property—Stiffening at
1.6 The following safety hazards caveat pertains only to the
Low Temperatures: Flexible Polymers and Coated Fabrics
test methods portion, Section 7, of this classification. This
D1084 Test Methods for Viscosity of Adhesives
standard does not purport to address all of the safety concerns,
D1349 Practice for Rubber—Standard Temperatures for
if any, associated with its use. It is the responsibility of the user
Testing
of this standard to establish appropriate safety and health
D1415 Test Method for Rubber Property—International
practices and determine the applicability of regulatory limita-
Hardness
tions prior to use.
D1566 Terminology Relating to Rubber
D1898 Practice for Sampling of Plastics
2. Referenced Documents
D2240 Test Method for Rubber Property—Durometer
2.1 ASTM Standards:
Hardness
C679 Test Method for Tack-Free Time of Elastomeric
D3182 Practice for Rubber—Materials, Equipment, and
Sealants
Procedures for Mixing Standard Compounds and Prepar-
D149 Test Method for Dielectric Breakdown Voltage and
ing Standard Vulcanized Sheets
D4800 Guide for Classifying and Specifying Adhesives
1 2.2 SAE Standard:
This classification is under the jurisdiction of ASTM Committee F03 on
Gaskets and is the direct responsibility of Subcommittee F03.30 on Classification. SAE J369 Flammability of Polymeric Interior Materials—
Current edition approved March 1, 2005. Published March 2005. DOI: 10.1520/
F2468-05.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Withdrawn.
Standards volume information, refer to the standard’s Document Summary page on Available from Society of Automotive Engineers (SAE), 400 Commonwealth
the ASTM website. Dr., Warrendale, PA 15096-0001.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
F2468 – 05
TABLE 1 Minimum Classification Requirements
Selection Property Designation
Order
Sequence
12 3 4 5 6 7 8 9
st
1 Digit Cure system Addition Acetoxy Alkoxy Amine Enoxy Oxime Free . As
(Cure by-product) (no by- (acetic (methanol, (cyclo- (acetone) (methyl ethyl radical specified
product) acid) ethanol) hexylamine) ketoxime)
nd
2 Digit Cure mechanism One-part Two-part One-part One-part One-part Two-part Radiation . As
moisture moisture radiation radiation- thermal thermal specified
A
cure cure cure moisture cure cure
cure
rd
3 Digit Application rate, g/min <50 50-99 100-199 200-299 300-499 500-749 750-999 >999 As
specified
th
4 Digit Test Method C679, <5 5-9.9 10-19.9 20-29.9 30-39.9 40-49.9 50-60 >60 As
Tack free time, min specified
th
5 Digit Test Methods D412 (Die C) <100 100-199 200-299 300-499 500-699 700-999 >999 . As
Ultimate elongation, % specified
th
6 Digit Test Methods D412, <0.345 0.345-0.690 0.691-1.035 1.036-1.380 1.381-3.450 3.451-6.899 6.90-14.0 >14 As
Tensile strength, MPa specified
th B
7 Digit Blowout resistance, s <10 10-20 21-30 31-40 41-50 51-60 >60 . As
specified
th
8 Digit Test Methods D792, <0.85 0.86-0.95 0.96-1.05 1.06-1.15 1.16-1.25 1.26-1.35 1.36-1.50 >1.5 As
Specific gravity, g/cc specified
th C
9 Digit Test Method D1002, <0.345 0.345-0.690 0.691-1.035 1.036-1.380 1.381-3.450 3.451-6.899 6.90-14.0 >14 As
Lap shear bond specified
strength, MPa
th
10 Digit Silicone volatile <0.6 0.6-1.0 1.1-1.9 2.0-2.9 3.0-4.9 5.0-6.9 7-10 >10 As
Content, % specified
A
Ultraviolet light (UV), microwave, or visible light cure.
B
Resistance to blowout refers to the time to failure at a standardized internal pressure using a fixture as agreed upon between producer and user.
C
Standard test conditions: 5 cm (1.97 in.)/min cross head speed, 1 mm (0.039 in.) gap, 1.27 cm (0.50 in.) overlap, Q panel 20204T3 Aluminum (as received).
Horizontal Test Method 3.2.8 volatiles—low molecular weight components of an
2.3 UL Standard: adhesive or sealant that can be extracted by the environment of
UL 94 Flammability the application.
3. Terminology 4. Significance and Use
3.1 Definitions—Some terms in this classification are de-
4.1 The purpose of this classification system is to provide a
fined in Terminiologies D907 and D1566.
method of adequately identifying silicone adhesives and seal-
3.2 Definitions of Terms Specific to This Standard:
ants through the use of a line call-out designation.
3.2.1 cure mechanism—the method of initiating the cure for
4.2 This classification system was designed to permit the
a silicone material.
addition of property values for future silicone adhesives and
3.2.2 cure system—the cross-linking mechanism the sili-
sealants.
cone material uses to transition to the elastomeric state.
5. Classification
3.2.3 draw-down—a method of sample preparation of vis-
cous and sag-resistant sealants, in which the sealant is leveled
5.1 A ten-digit numbering system is used to classify a
using a knife or tool to a specified thickness.
silicone adhesive and sealant cure system, cure mechanism,
3.2.4 formed in place gasket, fipg—a one- or two-
application rate, tack free time; ultimate elongation, tensile
component adhesive or sealant applied wet, uncured, to a joint
strength; blowout resistance, lap shear bond strength, specific
surface where the mating parts are assembled before the curing
gravity, and silicone volatile content as defined in Table 1. The
process is complete. When fully cured it forms a barrier to
firstcolumn(leftsideofthetable)indicatesthedigitnumberor
media migration across the joint. order sequence required while the designation numbers for
3.2.5 sag resistance—a property of some adhesives and
eachpropertyareindicatedonthetopofthetable.Theten-digit
sealants that enables the applied or extruded material to retain classification number must also be separated with hyphens
its shape before curing or cross-linking.
between the fourth and fifth digit, and the sixth and seventh
3.2.6 thixotropic—a rheological property of uncured seal- digit as seen in Example 1 (5.1.1).
ants in which the sealant resists sagging or slumping unless
5.1.1 Example 1—To specify a silicone adhesive or sealant
disturbed by an external force or pressure. with an acetoxy cure system, two-part moisture cure mecha-
3.2.7 transportation—any transportation venue involving
nism, application rate of 150 g/min, tack free time of 8 min,
land, sea, or air, civilian or military, stationary and small
400 % ultimate elongation, 1.2 MPa tensile strength, 15 s
engines.
blowout resistance, 1.1 specific gravity, 2.0 MPa lap shear
bond strength, and 2.5 % silicone volatile, the line call-out
would be:
Available from Underwriters Laboratories (UL), Corporate Progress, 333
Pfingsten Rd., Northbrook, IL 60062. ASTM F2468, 223224422454
F2468 – 05
where:
TABLE 2 Continued
2 = the acetoxy cure system,
Symbol Characteristic
2 = the two-part moisture cure,
E FLUID RESISTANCE—Test Method D471
3 = application rate between 100 and 199 g/min,
Second letter
2 = tack free time between 5 and 9.9 min, A = ASTM #1 Oil
B = IRM 902 Oil
4 = ultimate elongation between 300 and 499 %,
C = IRM 903 Oil
4 = tensile strength between 1.036 and 1.380 MPa,
D = ASTM SF105
2 = blowout resistance between 10 and 20 s,
E = ASTM B Fuel
4 = specific gravity between 1.06 and 1.15 g/cc, F = ASTM C Fuel
Q = as specified
5 = lap shear strength between 1.381 and 3.45 MPa, and
First digit–See Table 3 for time designation.
4 = silicone volatile content between 2.0 and 2.9 %.
Second digit–See Table 3 for temperature designation.
Third digit–See Table 4 for hardness change designation.
Fourth digit–See Table 4 for tensile change designation.
6. Line Call-Outs
Fifth digit–See Table 4 for elongation change designation.
6.1 A “line call-out,” which is a specification, shall contain
Sixth digit–See Table 4 for volume change designation.
F LOW TEMPERATURE—Test Methods D1053
the ASTM classification number F2468, a ten-digit prefix
G TEAR STRENGTH—Test Method D624
specifying the cure system, cure mechanism, application rate,
Second letter
tack free time, ultimate elongation, tensile strength, blowout
B = Die “B”
C = Die “C”
resistance, specific gravity, lap shear bond strength, and sili-
First digit–See Table 3 for time designatio
...