Specifications for Pressure Sensitive Adhesive Labels for Application to Covers of Bound Books for Use in Laser Printers

Specification Number 700-702-9/1/00

This specification is provided as a public service by the Preservation Directorate of the Library of Congress. Any commercial reproduction that implies endorsement of a product, service or materials, in any publication, is strictly prohibited by law. This Specification is written for L.C. purchasing purposes and is subject to change when necessary.

I. General Specifications - II. Product Requirements - III. Inspection

I. GENERAL SPECIFICATIONS

A. Face Stock

Composition Options
1. Polyester: White opaque film, 1-2 mil thick. The polyester must be biaxially oriented, non-recycled film with no plasticizers added.
2. Polypropylene: White opaque film, 1-2 mil thick. Biaxial orientation preferred.
The Procurement Request will clearly identify which of these face-stock materials is to be used for the particular application intended by the purchaser.
Degree of Whiteness
White pigmented label face-stocks must have a minimum brightness of 82% as measured by directional reflectance at 457 nm (TAPPI T452 cm-92).
Brightness Retention
Accelerated Aging: The color of the face-stock must not change more than 10 points of brightness as measured by directional reflectance at 457 nm when exposed for 28 days at 90°C and 50% RH. The brightness will be measured according to TAPPI T452 cm-92.

Photo Degradation: The color of the face-stock must not change more than 10 points of brightness as measured by directional reflectance at 457 nm when exposed 24 hours to a Xenon arc lamp in an Atlas Weatherometer under the following conditions: Irradiance Level: 1.0 watts/m² at 420 nm. Inner filter: Borosilicate glass. Outer filter: clear soda lime glass. Black panel temperature: 50°C. Wet bulb depression: 8.5°C. The brightness will be measured according to TAPPI T452 cm-92.

B. Adhesive

Composition
The pressure-sensitive adhesive layer must possess high permanence characteristics such that labels, once applied, can be removed only with difficulty. The adhesive layer must be clearly identifiable as an acrylic polymer or copolymer when analyzed by its infrared spectrum.
Bond Strength
The adhesive must demonstrate sufficient initial bond strength for the label to support a test weight of 200g for 10 minutes.

Test Method: This procedure is a 90-degree peel test, modified from ASTM D2860M-90. The bonding strength of the adhesive to four different substrates is assessed. These four test panels, are designated LC Standard Test Panels CM-1, CM-2, CM-3, and CM-4, consist of four different book covering materials applied to 3" x 6" sections of 60 pt. binder's board. The covering materials used for these LC Standard Test Panels have been selected to represent the wide range of book covers in any large collection.

A set of three labels, size 1" x 2 1/2 , is applied to each of the four Test Panels over a Mylar window that permits only a one inch square area of the adhesive side of the label to be in contact with the substrate, as illustrated in ASTM D2860M-90, procedure B. The labels are set in place by applying firm pressure with the edge of a 3M plastic applicator, model no. P.A.-1, to the labels in four downward strokes. The test samples are then allowed to cure for 7 days in an environmental chamber conditioned to 73° F and 50% RH.

At the end of this dwell time a 200 gram weight is suspended from the free end of the label and timed for 10 minutes. At the end of this test period, labels must not have peeled away from the substrate by more than 10 millimeters. Failure of this test with any of the four test panels will disqualify the stock and no further testing need be performed.
Bond Strength after Accelerated Aging
The adhesive, once set after the initial 7-day dwell time, must remain permanently affixed to both the face-stock and the substrate with no loss of adhesive strength for the life of the object to which it is applied, under conditions of normal use.

Test Method: This procedure is a 90-degree peel test, modified from ASTM D2860M-90.

A set of three labels is applied to Test Panel CM-1 in the same manner as described under Item 2 above. The labels are then subjected to accelerated aging at 80°C and 50% RH for 28 days. At the end of the aging period the test samples are placed in an environmental chamber conditioned to 73°F and 50% RH for 24 hours.

At the end of the conditioning period a 90° peel test is performed as in Item 2 above, with the exception that a 350 gram weight is used.

At the end of this test period, labels must not have peeled away from the substrate by more than 10 millimeters.

C. Other Label Properties

Curling/Lifting/Ooze
The labels must not show any sign of curling, lifting, buckling, or puckering, nor any evidence of the adhesive oozing beyond the label edges.

Test Method: A set of three labels, size 1 1/4" x 1 1/4", is applied toTest Panel CM-1 so that the entire adhesive side of the label is in contact with the substrate. The labels are set in place by applying firm pressure with the edge of a 3M plastic applicator, model no. P.A.-1, to the labels in four downward strokes.

The labels are then subjected to accelerated aging at 80°C and 50% RH for 28 days. At the end of the aging period, the labels are examined visually.
Print Fastness
The label stock must be able to accept and retain a clean, legible image from a laser printer.

The label stock will be printed with a test pattern consisting of a sample phrase or barcode centered on each label using a printer selected by the Library. The printer model to be used in this test will be noted on the purchase order. Inability to print the stock on the selected printer, obtain a clear, crisp and complete image, or read the bar-code with a scanner will constitute a failure. Any failure of the label stock during the printing process will disqualify the stock and no further testing will be performed.

Test Method: A strip of 3M Tape #230 is applied over the printed test pattern on the label by rubbing down the tape using three fingers in six firm strokes. The tape is then peeled back at a 180° angle. Legible characters visible on the test tape, and/or degradation of the printed image on the face-stock, constitute a failure. (This method is described in Archival Copies of Thermofax, Verifax and Other Unstable Records, Technical Information Paper No. 5, Washington, D.C., National Archives and Records Administration, 1990).
Abrasion Resistance of Printed Image
The printed image on the label must be able to resist moderate abrasive forces with minimal smudging of the ink.

Test Method: This procedure follows ASTM D5264-92.

Printed labels are attached to a piece of LC Standard Test Paper P-1 which has been cut to fit the base of the Sutherland Rub Tester. The test specimen is placed on the rubber pad on the base of the Sutherland Rub Tester, as described in ASTM D-5264-92, printed side facing the receptor block. The test specimen is then rubbed for 20 strokes using the A-1 Standard Receptor, Imperial Lapping Film with aluminum oxide 9-µm particles.

The extent of smudging is evaluated by selecting an area of the greatest density of smudged ink, 3-5 mm away from a printed character, and measuring its optical density using a reflectance densitometer. The density of the smudged area is compared to the density of a clean, unprinted, area of the label stock.

Density changes above 0.06 constitute a failure.
Effect on Photographic Material
If specified on the purchase order for use with collections of photographic materials, the labels must pass the Photographic Activity Test. Both the face stock and adhesive side of the label will be tested. Test to be conducted and results reported as described in ANSI IT9.16-1994, or latest revision. This test can be performed by the Image Permanence Institute (c/o Rochester Institute of Technology, Frank E. Gannett Memorial Building, P.O. Box 9887, Rochester, NY 14623-0887. Tel.: 716-475-5199, FAX: 716-475-7230) or other pre-approved laboratory.
Suitability for Cold Storage
The labels must be able to pass all of the tested properties listed above after being exposed to conditions of 0°C for 24 hours, followed by 24 hours at 73°F and 50% RH.

II. Additional Product Requirements

A. Problem-free Print Feeding

The label sheet must lie flat without any curling and permit problem-free self-feeding from a stacking paper tray.

B. Non-contamination of Printer by Adhesive Residue

The labels must not transfer adhesive to the platens or any other parts of a laser printer under extended, but normal use. There must not be any adhesive deposits on the platens or other accessible parts of the printer that can be seen visibly or felt by stickiness to the touch.

C. Odorlessness

The label stock must not emit odors deemed objectionable or hazardous to the work environment by the Library of Congress according to TAPPI T483.

D. Liner

The release liner under all label configurations must allow for easy and complete peeling of the face-stock without shearing of the adhesive layer.

E. Workmanship

All label edges will be cut square and clean, and sizes accurate to specification.

F. Shelf-Life

The adhesive must have a one year usable shelf-life such that the initial adhesion strength will be the same for labels applied up to one year after the original delivery date under ambient storage conditions. The labels must also maintain their capacity to be printed upon.

G. Dimensions

Dimensions will be specified on the purchase order.

H. Packaging

The items must be packed in standard commercial containers which are constructed to ensure that they are received in perfect condition - dry, undamaged and without kinks or creases. The outside of each container must be identified by type, size and number of items within, manufacturing run or batch number and Purchase Order number or Contract number.

III. Quality Assurance Inspection

A. Testing

Responsibility
The supplier is responsible for meeting all the requirements specified herein. The Library of Congress has the right to perform any of the tests set forth in the specification where such tests are deemed necessary to ensure that supplies conform to prescribed requirements.
Sampling
To sample for testing, shipments will be sampled according to MIL-STD-105E at inspection level S-2 with an acceptable quality level of 2.5 percent defective from each lot offered. Copies of MIL-STD-105E are available from Naval Publications and Forms Center; Standardization Document Order Department, Building 4, Section D; 700 Robbins Avenue; Philadelphia, Pennsylvania 19111-5094.
Materials
The following materials are required to perform the tests in this specification:
LC Standard Test Panel CM-1
LC Standard Test Panel CM-2
LC Standard Test Panel CM-3
LC Standard Test Panel CM-4
LC Standard Test paper P-1
Polyester (Mylar D)
3M Tape #230
3M Imperial Lapping Film, aluminum oxide 9-µm particles
Carey Lea Silver Test Film
Elite Photographic Paper
Whatman No. 1 filter paper
Methods
Tests will be conducted in accordance with specified test methods of the American National Standards Institute (ANSI), the American Society for Testing and Materials (ASTM), and the Technical Association of the Pulp and Paper Industry (TAPPI) and/or as described. Publications describing these tests may be ordered directly from the technical associations:
ANSI, 1430 Broadway, New York, NY 10018
ASTM, 100 Barr Harbor Drive, W. Conshohocken, PA 19428-2959
TAPPI, One Dunwoody Park, Atlanta, GA 30348
Tests

Requirements		Test Method
Brightness, initial	> 82%	TAPPI T452 om-92
Brightness, after aging	< 10 pts. change	TAPPI T452 om-92
Photo Degradation	< 10 pts. change	APPI T 452 om-92
Adhesive ID	acrylic	infrared spectrum
Bond Strength	200g, < 10 mm peel	ASTM D2860M-90 (modified)
Bond Strength - Aged	350g, < 10 mm peel	ASTM D2860M-90 (modified), after aging
Curling/Lifting/Ooze	none	visual, after aging
Print Fastness	no legible characters on tape	NARA Technical Information Paper No. 5
Print Abrasion	< 0.06 pts. density change	ASTM D5264-92
P.A.T.	pass	ANSI IT9.16-1994

FAILURE TO MEET ANY OF THE SPECIFICATIONS WILL BE CAUSE FOR REJECTION.

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