1、Designation: D2851 98 (Reapproved 2015)D2851 15Standard Specification forLiquid Optical Adhesive1This standard is issued under the fixed designation D2851; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision.
2、A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This specification covers liquid optical adhesive for use in bonding glass to glass or other transparent adherends.1.2 The values sta
3、ted in SI units are to be regarded as standard. The values given in parentheses are provided for informationpurposes only.1.3 The following precautionary caveat pertains only to the test method portion, Section 6, of this specification: This standarddoes not purport to address all of the safety conc
4、erns, if any, associated with its use. It is the responsibility of the user of thisstandard 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 Documents2.1 ASTM
5、 Standards:2D542 Test Method for Index of Refraction of Transparent Organic PlasticsD897 Test Method for Tensile Properties of Adhesive BondsD904 Practice for Exposure of Adhesive Specimens to Artificial LightD907 Terminology of AdhesivesD1084 Test Methods for Viscosity of AdhesivesE308 Practice for
6、 Computing the Colors of Objects by Using the CIE SystemE1953 Practice for Description of Thermal Analysis and Rheology Apparatus3. Terminology3.1 DefinitionsMany terms in this specification are defined in Terminology D907.4. Significance and Use4.1 The bond strength tests provide reasonably accurat
7、e information with regard to the bond strength of the adhesives. Bondstrength 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
8、rate and type of loading.5. General Requirements5.1 The adhesive shall be in liquid form and free of solvent in order to avoid bubble formation in the adhesive layer. Eachcomponent shall be completely reactive (without residual volatile products). The adhesive may be heat-, catalyst-, orradiation-cu
9、red.5.1.1 VolatilityVolatile content of the adhesive shall not exceed 0.5 %, unless otherwise agreed upon between themanufacturer and the purchaser.5.1.2 ViscosityThe viscosity of the adhesive shall be within a well-defined range as agreed upon between the manufacturerand the purchaser.5.1.3 ColorTh
10、e color of the adhesive shall not exceed the color of a platinum-cobalt standard solution No. 300.1 This specification is under the jurisdiction of ASTM Committee D14 on Adhesives and is the direct responsibility of Subcommittee D14.60 on Adhesive MaterialClassification System.Current edition approv
11、ed April 1, 2015Sept. 1, 2015. Published April 2015September 2015. Originally approved in 1970. Last previous edition approved in 20092015 asD2851 98 (2009).(2015). DOI: 10.1520/D2851-98R15.10.1520/D2851-15.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer
12、Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.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 pre
13、vious version. Becauseit 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 versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM I
14、nternational, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States15.1.4 CleanlinessThe number and size of foreign particles found in 100 mL of the adhesive shall not exceed 5 particles in thesize range from 10 to 100 m (0.1 mm), and none larger than 100 m. The number
15、and size of foreign particles in the catalystrequired to cure 100 mL of the adhesive shall not exceed 2 particles in the size range from 10 to 100 m, and none larger than100 m.5.1.5 Refractive IndexThe refractive index of the cured adhesive shall be within a well-defined range as agreed upon between
16、the manufacturer and the purchaser.5.1.6 StabilityThe liquid adhesive shall not change in viscosity by greater than 20 % of its original viscosity nor show anyformation of solids, when tested as described in 6.6.5.1.7 Light TransmissionVisible light transmission through a bonded glass doublet (two g
17、lass disks bonded as described in6.8) shall not be less than 98.5 % of the total light transmitted through a single glass disk. There shall be no change in lighttransmission of a glass doublet after the environmental test (see 6.9).5.1.8 Environmental TestSeparation within the adhesive layer or from
18、 either glass surface of the glass doublet shall not exceed1.0 mm in depth nor extend beyond 180 of the periphery of the adhesive layer (see 6.9).5.1.9 Bond StrengthThe tensile strength of a bonded glass doublet after being subjected to the environmental test (see 6.9)shall be greater than 200 psi (
19、1.38 MPa) or any value agreed upon between the manufacturer and the purchaser.6. Test Methods6.1 Volatility:6.1.1 Thoroughly clean three petri dish bottoms, 95-mm outside diameter, by washing with detergent and a scrub brush. Rinsewith warm running tap water. Place petri dishes in an air-circulating
20、 oven for 30 min at 65 6 2C (150 6 4F). Raise temperatureto 110 6 2C (230 6 4F) for 1 h. Remove petri dishes from oven and place in a desiccator.After petri dishes have cooled to roomtemperature, approximately 2 h, weigh each dish to the nearest 0.1 mg. (WarningIn addition to other precautions, do n
21、ot handlepetri dishes with bare hands. Use tongs.)6.1.2 Replace each petri dish in the oven at 110 6 2C (230 6 4F) for 1 h. Repeat cool-down procedure. Reweigh each petridish 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
22、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
23、the manufacturer. Then placeeach sample in an oven at 105 6 2C (220 6 4F) to a constant weight (same procedure as in 5.1.1 but at 105C). Reweigh eachsample to the nearest 0.1 mg and calculate the percent volatile matter as follows.Volatile matter,%5A 2B!/A# 3100 (1)where:A = weight of original sampl
24、e, andB = weight of cured adhesive taken to constant weight.6.2 ViscosityMeasure the viscosity of the adhesive in accordance with Test Methods D1084. (Brookfield, (RotationalViscometer, Method B, or anysee Practice E1953other suitable viscometer may be used.).)6.3 ColorDetermine the color of the adh
25、esive by comparing it with platinum-cobalt (Pt-Co) standards. Place 100 mL ofadhesive in a 100-mL Nessler tube. Make color observations by placing the adhesive-filled Nessler tube vertically over a sheet ofwhite paper while looking down and through the filled tube. Compare the color observed with a
26、standard Nessler tube, containing100 mL of the Pt-Co standard held in the same manner.6.3.1 Prepare the Pt-Co standard solutions by dissolving 1.246 g of potassium platinic chloride and 1000 g of cp crystallinecobaltous chloride hexahydrate in a solution of 300 mL of distilled water and 100 mL of co
27、ncentrated hydrochloric acid. Diluteto 1000 mL in a volumetric flash using distilled water. This shall be the concentrated stock solution that has a Pt-Co number of500. Dilute the concentrated stock solution with distilled water as shown below to obtain the desired Pt-Co standard.D2851 152Pt-Co Stoc
28、k Solution Distilled H2ONumber of Pt-Co 500, mL to Be Added, mL500 100 0450 90 10400 80 20350 70 30300 60 40250 50 50200 40 60150 30 70100 20 8075 15 8550 10 900 0 100Store the stock solutions in clean glass bottles and stopper them to prevent evaporation loss.6.4 Foreign Particle ContentInspect a 1
29、00-mL sample of the liquid adhesive and a sample of its catalyst for cleanliness byfiltering each through a low-form Gooch crucible fitted with a filter membrane of 5.0 to 10.0-m pore size and a color suitableto easily detect and examine foreign particles. Measure the size of the particles by means
30、of a calibrated traversing microscope(10) or other equivalent means. If the viscosity of the sample is too high, dilute it with any clean and suitable solvent to permiteasy flow of the liquid through the filter membrane.6.5 Refractive IndexPrepare a solid adhesive specimen by measuring approximately
31、 6.3 by 12.7 by 12.7 mm (0.25 by 0.5 by0.5 in.). Make two adjacent surfaces measuring 6.3 by 12.7 mm flat (0.25 by 0.5 in.), smooth, and perpendicular to each other.Polish by means of a rotating (500 r/min) felt-covered polishing wheel wetted with a solution of cerium oxide (polishing grade)in water
32、. Use the polished surface in contact with the prism. Determine the index of refraction in accordance with the refractometricmethod described in Test Method D542. The contacting fluid between the prism and the adhesive surface may bebromonaphthalene. A fluid with a closer matching refractive index c
33、an be prepared by diluting the bromonaphthalene with refinedmineral oil (medicinal grade).6.6 StabilityPlace the adhesive in an air-circulating oven at 57 6 1.1C (135 6 2F) for 168 h or at any temperature or timeagreed upon between the manufacturer and the user.6.7 Light TransmissionDetermine the vi
34、sible light transmission in accordance with Practice E308. The specimen shall consistof a bonded glass doublet prepared as described in 6.8. Make a comparison with the light transmission through one glass disksimilar to the one used for preparing the doublet. Clean the glass disk as described in pre
35、paring the disk for bonding. All threedoublets shall pass. Retain for environmental test (see 6.9).6.8 Glass Doublet PreparationThe flat and polished plate glass (silvering grade) disks shall be 31.756 0.8 mm (1.25 6 0.03in.) in diameter and 6.35 mm (0.25 in.) thick, with edges lightly ground to rem
36、ove their sharpness. Clean with a camels hair brushthat is wet with ethanol. Rinse the flat surface to be bonded in a stream of clean ethanol and then allow it to dry in a desiccatorfor 1 h. Apply the adhesive, prepared in accordance with manufacturers instructions, dropwise to the center of one of
37、the cleanand dry disks. Place a second disk over the drop of adhesive with a rotary motion so that the adhesive spreads thinly and uniformlybetween the two glass surfaces without trapping air bubbles. Wipe excess adhesive from the periphery of the assembly and curethe film as recommended by the adhe
38、sive manufacturer. Three doublets are required for tests.6.9 Environmental TestUse the specimens for the environmental test that passed the light transmission test as described in5.1.7. The environmental test shall consist of the following exposure tests, in the order indicated.(a) Immersion in dist
39、illed water at 38 6 1.1C (100 6 2F) for 20 h.(b) Exposure to 54 6 1.1C (65 6 2F) for 20 h.(c) Exposure to 71 6 1.1C (160 6 2F) and 100 % relative humidity for 20 h.(d) Exposure to accelerated weathering for 20 h in accordance with Practice D904.6.9.1 Subject three glass doublets that passed the ligh
40、t transmission test to the environmental test. In performing the test, coolor heat the doublets gradually, over a period of not less than 2 h, and return them to room temperature in the same gradual manner.Examine each doublet for edge separation or other imperfection.All three doublets shall pass t
41、he environmental test for separationand light transmission. Retain the three glass doublets for bond strength determination (6.10).6.10 Bond StrengthBond each of the three glass doublets passing the test described in 6.9 to metal tensile specimens,described in Test Method D897, to form a metal-to-do
42、ublet-to-metal bonded assembly. Use a room temperature curing adhesive,such as an epoxy, having a tensile bond strength between metal and glass of approximately 2000 psi (13.8 MPa) to bond the doubletto the metal surface. Three assemblies shall be prepared and tested in tension as described in Test
43、Method D897, and all shall pass.Bond strengths at temperatures other than room temperature shall be made upon agreement between the manufacturer and thepurchaser.D2851 1537. Keywords7.1 adhesive; liquid; opticalASTM International takes no position respecting the validity of any patent rights asserte
44、d in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by th
45、e responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn.Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive c
46、areful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM Internati
47、onal, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the Copyright Clearance Center, 222Rosewood Drive, Danvers, MA 01923, Tel: (978) 646-2600; http:/ 154
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