ASTM D2851-98(2015)

Standard Specification for Liquid Optical Adhesive

ABSTRACT
This specification covers liquid optical adhesive for use in bonding glass to glass or other transparent adherends. The adhesive shall be in liquid form and free of solvent in order to avoid bubble formation in the adhesive layer. Each component shall be completely reactive. The adhesive may be heat-, catalyst-, or radiation-cured. Voltatility, color, viscosity, foreign particle content, refractive index, stability, light transmission, glass doublet preparation, environmental test, and bond strength tests shall be performed in accordance with the specified requirements.
SCOPE
1.1 This specification covers liquid optical adhesive for use in bonding glass to glass or other transparent adherends.  
1.2 The values stated in SI units are to be regarded as standard. The values given in parentheses are provided for information purposes only.  
1.3 The following precautionary caveat pertains only to the test method portion, Section 6, of this specification: 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. Specific precautionary statements are given in 6.1.1.

General Information

• Status: Historical
• Publication Date: 31-Mar-2015
• ICS: 83.180 - Adhesives
• Technical Committee: D14 - Adhesives
• Drafting Committee: D14.60 - Adhesive Material Classification System

Relations

• Replaces: ASTM D2851-98(2009) - Standard Specification for Liquid Optical Adhesive
• Effective Date: 01-Apr-2015

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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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:D2851 −98(Reapproved 2015)
Standard Specification for
Liquid Optical Adhesive
This standard is issued under the fixed designation D2851; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope Bond strength data may be suitable for specification
acceptance, service evaluation, manufacturing control,
1.1 This specification covers liquid optical adhesive for use
research, and development. Bond strength tests are not consid-
in bonding glass to glass or other transparent adherends.
ered significant for applications differing widely from the test
1.2 The values stated in SI units are to be regarded as
in rate and type of loading.
standard. The values given in parentheses are provided for
information purposes only.
5. General Requirements
1.3 The following precautionary caveat pertains only to the
5.1 The adhesive shall be in liquid form and free of solvent
test method portion, Section 6, of this specification: This
in order to avoid bubble formation in the adhesive layer. Each
standard does not purport to address all of the safety concerns,
component shall be completely reactive (without residual
if any, associated with its use. It is the responsibility of the user
volatile products). The adhesive may be heat-, catalyst-, or
of this standard to establish appropriate safety and health
radiation-cured.
practices and determine the applicability of regulatory limita-
5.1.1 Volatility—Volatile content of the adhesive shall not
tions prior to use. Specific precautionary statements are given
exceed 0.5%, unless otherwise agreed upon between the
in 6.1.1.
manufacturer and the purchaser.
2. Referenced Documents
5.1.2 Viscosity—The viscosity of the adhesive shall be
within a well-defined range as agreed upon between the
2.1 ASTM Standards:
manufacturer and the purchaser.
D542Test Method for Index of Refraction of Transparent
5.1.3 Color—The color of the adhesive shall not exceed the
Organic Plastics
color of a platinum-cobalt standard solution No. 300.
D897Test Method forTensile Properties ofAdhesive Bonds
5.1.4 Cleanliness—Thenumberandsizeofforeignparticles
D904Practice for Exposure of Adhesive Specimens to
foundin100mLoftheadhesiveshallnotexceed5particlesin
Artificial Light
the size range from 10 to 100 µm (0.1 mm), and none larger
D907Terminology of Adhesives
than 100 µm. The number and size of foreign particles in the
D1084Test Methods for Viscosity of Adhesives
catalyst required to cure 100 mL of the adhesive shall not
E308PracticeforComputingtheColorsofObjectsbyUsing
exceed 2 particles in the size range from 10 to 100 µm, and
the CIE System
none larger than 100 µm.
3. Terminology
5.1.5 Refractive Index—The refractive index of the cured
3.1 Definitions—Many terms in this specification are de- adhesive shall be within a well-defined range as agreed upon
fined in Terminology D907. between the manufacturer and the purchaser.
5.1.6 Stability—The liquid adhesive shall not change in
4. Significance and Use
viscosity by greater than 20% of its original viscosity nor
4.1 The bond strength tests provide reasonably accurate
show any formation of solids, when tested as described in 6.6.
information with regard to the bond strength of the adhesives.
5.1.7 Light Transmission—Visible light transmission
through a bonded glass doublet (two glass disks bonded as
This specification is under the jurisdiction of ASTM Committee D14 on described in 6.8) shall not be less than 98.5% of the total light
Adhesives and is the direct responsibility of Subcommittee D14.60 on Adhesive
transmitted through a single glass disk. There shall be no
Material Classification System.
change in light transmission of a glass doublet after the
Current edition approved April 1, 2015. Published April 2015. Originally
environmental test (see 6.9).
approved in 1970. Last previous edition approved in 2009 as D2851–98(2009).
DOI: 10.1520/D2851-98R15.
5.1.8 Environmental Test—Separation within the adhesive
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
layer or from either glass surface of the glass doublet shall not
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
exceed 1.0 mm in depth nor extend beyond 180° of the
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. periphery of the adhesive layer (see 6.9).
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D2851−98 (2015)
5.1.9 Bond Strength—Thetensilestrengthofabondedglass
Pt-Co Stock Solution Distilled H O
Number of Pt-Co 500, mL to Be Added, mL
doubletafterbeingsubjectedtotheenvironmentaltest(see6.9)
500 100 0
shall be greater than 200 psi (1.38 MPa) or any value agreed
450 90 10
upon between the manufacturer and the purchaser.
400 80 20
350 70 30
300 60 40
6. Test Methods
250 50 50
6.1 Volatility: 200 40 60
150 30 70
6.1.1 Thoroughly clean three petri dish bottoms, 95-mm
100 20 80
outsidediameter,bywashingwithdetergentandascrubbrush.
75 15 85
Rinse with warm running tap water. Place petri dishes in an 50 10 90
0 0 100
air-circulatingovenfor30minat65 62°C(150 64°F).Raise
Store the stock solutions in clean glass bottles and stopper
temperature to 110 6 2°C (230 6 4°F) for 1 h. Remove petri
them to prevent evaporation loss.
dishes from oven and place in a desiccator. After petri dishes
have cooled to room temperature, approximately 2 h, weigh
6.4 Foreign Particle Content—Inspect a 100-mL sample of
each dish to the nearest 0.1 mg. (Warning—In addition to
the liquid adhesive and a sample of its catalyst for cleanliness
other precautions, do not handle petri dishes with bare hands.
byfilteringeachthroughalow-formGoochcruciblefittedwith
Use tongs.)
a filter membrane of 5.0 to 10.0-µm pore size and a color
6.1.2 Replaceeachpetridishintheovenat110 62°C(230
suitabletoeasilydetectandexamineforeignparticles.Measure
6 4°F) for 1 h. Repeat cool-down procedure. Reweigh each
the size of the particles by means of a calibrated traversing
petridishtothenearest0.1mg.Ifweightagreestowithin 60.2
microscope(10×)orotherequivalentmeans.Iftheviscosityof
mg of initial weight, proceed to 6.1.3. If weight exceeds this
the sample is too high, dilute it with any clean and suitable
60.2-mgrange,repeatprocessuntilaconstantweightforeach
solvent to permit easy flow of the liquid through the filter
petri dish is obtained.
membrane.
6.1.3 Toeachpetridishaddapproximately10gofadhesive,
6.5 Refractive Index—Prepare a solid adhesive specimen by
and mix with catalyst or any component
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D2851 − 98 (Reapproved 2009) D2851 − 98 (Reapproved 2015)
Standard Specification for
Liquid Optical Adhesive
This standard is issued under the fixed designation D2851; 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
1.1 This specification covers liquid optical adhesive for use in bonding glass to glass or other transparent adherends.
1.2 The values stated in SI units are to be regarded as standard. The values given in parentheses are provided for information
purposes only.
1.3 The following precautionary caveat pertains only to the test method portion, Section 6, of this specification: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.Specific precautionary statements are given in 6.1.1.
2. Referenced Documents
2.1 ASTM Standards:
D542 Test Method for Index of Refraction of Transparent Organic Plastics
D897 Test Method for Tensile Properties of Adhesive Bonds
D904 Practice for Exposure of Adhesive Specimens to Artificial Light
D907 Terminology of Adhesives
D1084 Test Methods for Viscosity of Adhesives
E308 Practice for Computing the Colors of Objects by Using the CIE System
3. Terminology
3.1 Definitions—Many terms in this specification are defined in Terminology D907.
4. Significance and Use
4.1 The bond strength tests provide reasonably accurate information with regard to the bond strength of the adhesives. Bond
strength data may be suitable for specification acceptance, service evaluation, manufacturing control, research, and development.
Bond strength tests are not considered significant for applications differing widely from the test in rate and type of loading.
5. General Requirements
5.1 The adhesive shall be in liquid form and free of solvent in order to avoid bubble formation in the adhesive layer. Each
component shall be completely reactive (without residual volatile products). The adhesive may be heat-, catalyst-, or
radiation-cured.
5.1.1 Volatility—Volatile content of the adhesive shall not exceed 0.5 %, unless otherwise agreed upon between the
manufacturer and the purchaser.
5.1.2 Viscosity—The viscosity of the adhesive shall be within a well-defined range as agreed upon between the manufacturer
and the purchaser.
5.1.3 Color—The color of the adhesive shall not exceed the color of a platinum-cobalt standard solution No. 300.
This specification is under the jurisdiction of ASTM Committee D14 on Adhesives and is the direct responsibility of Subcommittee D14.60 on Adhesive Material
Classification System.
Current edition approved Nov. 1, 2009April 1, 2015. Published November 2009April 2015. Originally approved in 1970. Last previous edition approved in 20042009 as
D2851 – 98 (2004).(2009). DOI: 10.1520/D2851-98R09.10.1520/D2851-98R15.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’sstandard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D2851 − 98 (2015)
5.1.4 Cleanliness—The number and size of foreign particles found in 100 mL of the adhesive shall not exceed 5 particles in the
size range from 10 to 100 μm (0.1 mm), and none larger than 100 μm. The number and size of foreign particles in the catalyst
required to cure 100 mL of the adhesive shall not exceed 2 particles in the size range from 10 to 100 μm, and none larger than
100 μm.
5.1.5 Refractive Index—The refractive index of the cured adhesive shall be within a well-defined range as agreed upon between
the manufacturer and the purchaser.
5.1.6 Stability—The liquid adhesive shall not change in viscosity by greater than 20 % of its original viscosity nor show any
formation of solids, when tested as described in 6.6.
5.1.7 Light Transmission—Visible light transmission through a bonded glass doublet (two glass disks bonded as described in
6.8) shall not be less than 98.5 % of the total light transmitted through a single glass disk. There shall be no change in light
transmission of a glass doublet after the environmental test (see 6.9).
5.1.8 Environmental Test—Separation within the adhesive layer or from either glass surface of the glass doublet shall not exceed
1.0 mm in depth nor extend beyond 180° of the periphery of the adhesive layer (see 6.9).
5.1.9 Bond Strength—The tensile strength of a bonded glass doublet after being subjected to the environmental test (see 6.9)
shall be greater than 200 psi (1.38 MPa) or any value agreed upon between the manufacturer and the purchaser.
6. Test Methods
6.1 Volatility:
6.1.1 Thoroughly clean three petri dish bottoms, 95-mm outside diameter, by washing with detergent and a scrub brush. Rinse
with warm running tap water. Place petri dishes in an air-circulating oven for 30 min at 65 6 2°C (150 6 4°F). Raise temperature
to 110 6 2°C (230 6 4°F) for 1 h. Remove petri dishes from oven and place in a desiccator. After petri dishes have cooled to room
temperature, approximately 2 h, weigh each dish to the nearest 0.1 mg. (Warning—In addition to other precautions, do not handle
petri dishes with bare hands. Use tongs.)
6.1.2 Replace each petri dish in the oven at 110 6 2°C (230 6 4°F) for 1 h. Repeat cool-down procedure. Reweigh each petri
dish to the nearest 0.1 mg. If weight agrees to within 60.2 mg of initial weight, proceed to 6.1.3. If weight exceeds this 60.2-mg
range, repeat process until a constant weight for each petri dish is obtained.
6.1.3 To each petri dish add approximately 10 g of adhesive, and mix with catalyst or any component part required for curing.
Weigh each dish to the nearest 0.1 mg. Cure the adhesive by following the procedure described by the manufacturer. Then place
each sample in an oven at 105 6 2°C (220 6 4°F) to a constant weight (same procedure as in 5.1.1 but at 105°C). Reweigh each
sample to the nearest 0.1 mg and calculate the percent volatile matter as follows.
Volatile matter,%5 @~A 2 B!/A# 3100 (1)
where:
A = weight of original sample, and
B = weight of cured adhesive taken to constant weight.
where:
A = weight of original sample, and
B = weight of cured adhesive taken to constant weight.
6.2 Viscosity—Measure the viscosity of the adhesive in accordance with Test Methods D1084. (Brookfield, Method B, or any
other suitable viscometer may be used.)
6.3 Color—Determine the color of the adh
...