1.1 Purpose.—The purpose of this Commercial Standard is to promulgate minimum standards for vinyl plastic film in order to maintain the quality of the materials in question for the mutual protection of manufacturers and consumers.

1.2 Scope. —This standard covers methods of test and requirements for general purpose vinyl plastic film to insure satisfactory products for consumer use. The requirements and methods of test specify thickness tolerances, yield per roll, width tolerances, shrinkage at elevated temperatures, contamination, appearance, crocking, tensile properties, tear resistance, volatility of plasticizer, water extraction, low-temperature impact, and flammability. Suggested forms for declaring compliance with the standard and an identifying hallmark are included.

1.3 General description of products covered. —The material covered is nonrigid, unsupported, vinyl plastic film 10 mils and less in thickness, including transparent, translucent, and opaque material, whether plain, embossed, molded or otherwise surface treated.

2.1 Thickness. —The average thickness of the film shall be within ± 10 percent of that specified. The average thickness shall be determined from five uniformly spaced readings taken across the width of the sheet. The referee test method for average thickness shall be the method described in paragraph 4.1.

2.1.1 Average thickness based on yield per roll.—The yield of material in any one roll shall be based on average thickness of the film, which shall be ± 5 percent of the thickness specified, calculated as follows:

2.2 Width. —The film shall be held to a tolerance of + ½ − 0 in. of the width specified by the purchaser and agreed to by the manufacturer. This tolerance shall apply when the material is in roll form on the core.

2.3 Length. —The length of material, excluding that which has been subjected to embossing, printing, etc., shall be continuous in any one roll, and the total length in a roll shall be as agreed to by the manufacturer and the purchaser.

3.1 Shrinkage at elevated temperatures. —The average dimensional change shall be not greater than 7 percent in any direction when the film is tested at a temperature of 100° C for 30 minutes in accordance with the method referred to in paragraph 4.2.

3.2 Contamination. —The material shall be as free as is commercially practicable from pinholes, particles of foreign matter, and undispersed raw materials. The material shall have no visible holes.

3.3 Appearance. —The material shall be as free as is commercially practicable from visual defects, e. g., “cold-checks,” “crow's feet,” “pine trees,” “streaks,” and “blisters.” It shall also have smooth edges, free from cuts and nicks.

3.4 Crocking. —The amount of color transferred from the specimen under examination to the white test square shall not be perceptible when the material is tested in accordance with the method described in paragraph 4.3.

3.5 Tensile properties. —The minimum average tensile strength of the material, when tested in accordance with the method referred to in paragraph 4.4, shall be 2,100 psi when tested with the pendulum-type machine and 2,300 psi when a static-controlled separation-type machine is used. Either of these methods may be used. If the film meets the requirement by any one method, the film shall be considered as passed. The minimum ultimate elongation of the materials shall be 150 percent.

3.6 Tensile tear resistance. —The minimum average tensile tear strength of the film (either plain or after embossing, if embossed) in any direction shall be 200 lb/in. when tested in accordance with the method referred to in paragraph 4.5.

3.7 Elmendorf tear resistance.—The minimum average Elmendorf tear strength of the film (either plain or after embossing, if embossed) in any direction shall be 180 grams per sheet for film 3 mils or less in thickness, and 60 grams per mil for film greater than 3 mils in thickness, when tested in accordance with the method referred to in paragraph 4.6.

3.8 Plasticizer volatility. —The average weight loss based on initial film weight shall be not more than 10 percent for film 3 mils or less in thickness, 9 percent for film 4 mils, 7 ½ percent for film 6 mils, and 5 percent for film 8 mils in thickness, when tested at a temperature of 70° ± 2° C (158° ± 3.6° F) for 24 hours in accordance with the method referred to in paragraph 4.7.

3.9 Water extraction. — The material shall show not more than 1 percent average loss lay weight when tested in accordance with the method referred to in paragraph 4.8.

3.10 Low-temperature impact. —Not more than 2 specimens out of 10 shall fail when tested at a temperature of -17.8° ± 2° C (0° ± 3.6° F) in accordance with the method described in paragraph 4.9.

3.11 Flammability.—The rate of burning shall not exceed 1.2 in./sec as judged by the average of five determinations length wise and five determinations transverse to the direction of processing, when the material is tested with the SPI flammability tester in accordance with the method described in paragraph 4.10.

Note.—Light stability. At the industry meeting on November 18, 1952, the desirability of including a requirement for light stability was discussed at some length.

The Society of the Plastics Industry (SPI) Committee which prepared this recommended, Commercial Standard for general purpose vinyl plastic film recognized the value and need of such a requirement. However, after years of work by the SPI group, which was assigned the problem of selecting or developing a suitable method of test for light stability, as well as the enormous amount of work done by the American Society for Testing Materials and various governmental agencies, such as the National Bureau of Standards, no suitable method has been found or developed. Two major difficulties have been encountered: (1) the poor degree of reproducibility between different pieces of apparatus of the same type; (2) the poor degree of correlation between laboratory light stability tests and service behavior.

The SPI group working on light stability hopes to have a reasonably satisfactory method in a year or two. It was the opinion of the committee recommending this specification for promulgation as a Commercial Standard that it would be more of a detriment to the plastic film industry than a benefit to wait for another 2 years to issue this standard because of the lack of this one test. When a suitable test method is developed, the Commercial Standard call be revised. Any help which anyone can offer to the SPI group will be appreciated.

4.1 Average thickness (weight method).

4.1.1 Apparatus.

(a) Analytical balance, equipped with pan straddle or other stationary support, sensitive to 0.0005 gm.

(b) Class S. weights.

(c) Beaker, 250 ml.

(d) Fine nonabsorbent thread or wire.

(e) Thermometer, 0° to 100° C, graduated in 1° divisions.

(f) Die or template, for cutting test specimens, 10 cm by 10 cm, with a dimensional tolerance of ± 0.01 cm per side.

(g) Sharp knife or razor.

4.1.2 Test specimens. —Five 10-cm by 10-cm specimens taken uniformly across the width of the sheet shall be tested.

4.1.3 Test conditions. —The specimens shall be conditioned and tested in accordance with procedure A of ASTM¹ D618, Tentative Methods of Conditioning Plastics and Electrical Insulating Materials for Testing.

4.1.4 Procedure.

4.1.4.1 By means of the die or template and the sharp knife or razor, cut five specimens from the sample of material.

4.1.4.2 Weigh each specimen to the nearest 0.5 mg on the analytical balance. Record the weight as W.

4.1.4.3 Following the procedure of ASTM D792, Methods of Test for Specific Gravity of Plastics, method A, determine the specific, gravity of each specimen and record as D. Use of a wetting agent is recommended.

4.1.5 Calculations. —Calculate the average thickness of each test specimen, using the following formula, and average the two values.

T = 394W = 3.94 W,

where

T = average thickness of test, specimen in mils

W = weight of test specimen in gm

D = density of test specimen in gm/cc (specific gravity = density in metric units)

394= conversion factor, cm to mils

100= area of specimen in sq cm

4.2 Shrinkage at elevated temperatures.—The dimensional change shall be determined in accordance with ASTM D1204, Method of Test for Measurement of Changes in Linear Dimensions of Nonrigid Thermoplastics Sheeting and Film.

4.3 Crocking.

4.3.1 Definition. —Colorfastness to rubbing (crocking) is understood to be resistance to physical transfer of color from the material tested to a piece of white cotton under the conditions of the test.

4.3.2 Apparatus. —AATCC Crockmeter. (Crockmeter and cloth, 2- by 2-in. test squares, may be obtained from the secretary of the American Association of Textile Chemists & Colorists, Lowell Textile Institute, Lowell, Mass.)

4.3.3 Materials. —White bleached cotton cloth, starch-free, cut into 2-in. test squares. Lawns, percales, or printcloths are suitable. (See par. 4.3.2).

4.3.4 Test specimens.—Two 2- by 5-in. specimens of film shall be used, one for the dry test and one for the wet test.

4.3.5 Procedure. —The test specimen shall be preconditioned in accordance with ASTM D618, procedure A, Tentative Methods of Conditioning Plastics and Electrical Insulating Materials for Testing. The test specimen shall then be placed on the base of the Crockmeter so as to rest flat on the abrasive cloth with its long dimension in the direction of the rubbing. The square of white testing cloth is mounted over the end of the finger which projects downward from the slide, with the weave oblique to the direction of rubbing, and is held in place by the spiral clip. The covered finger of the slide is then placed on the test specimen and is slid back and forth for 20 rubbings, that is, for 10 steady turns of the crank at the rate of 1 turn per second.

For wet rubbing (crocking) tests, the white testing square is thoroughly wet out in distilled water, squeezed, and then passed through a wringer between two sheets of filter paper just before use. Otherwise the procedure for wet rubbing is the same as for dry rubbing.

Accidental damage to the rubbing finger, spiral clip, or abrasive cloth may be repaired when noticeable as follows: The abrasive cloth is neatly renewed; the clip is bent further open or shut over an inserted rod of the correct diameter, as required; and the finger is resurfaced by movement on an extra piece of fine emery cloth in a manner simulating regular use.

4.4 Tensile properties.—The tensile strength and elongation shall be determined in accordance with method B of ASTM D882, Methods of Test for Tensile Properties of Thin Plastic Sheets and Films, using specimens 1 in. wide. The thickness of the specimens tested shall be determined as described in paragraph 4.1.

4.5 Tensile tear resistance.—The tensile tear strength shall be determined in accordance with ASTM D1004, Method of Test for Tear Resistance of Plastic Film and Sheeting. The thickness of the specimens tested shall be determined as described in paragraph 4.1.

4.6 Elmendorf tear resistance.—The Elmendorf tear strength shall be determined in accordance with ASTM D689, Method of Test for Internal Tearing Resistance of Paper, except that readings obtained where the tear deviates more than 10 mm (⅜ in.) from the line of the initial slit shall not be rejected when obtained with embossed films. The thickness of the specimens tested shall be determined as described in paragraph 4.1.

4.7 Plasticizer volatility. —The plasticizer volatility shall be determined in accordance with ASTM D1203, Method of Test for Volatile Loss from Plastic Materials.

4.8 Water extraction.—The percentage loss in weight from extraction by distilled water shall be determined in accordance with ASTM D1239, Method of Test for Resistance of Plastic Films to Extraction by Chemicals, except that the specimens shall be preconditioned for 3 hours at 50° ± 3° C (122° ± 5.4° F), removed from the oven, placed in the desiccator, and allowed to cool to room temperature before weighing. Also, the immersion test shall be made for 24 hours at 50° ± 3° C (122° ± 5.4° F) in distilled water only.

4.9 Low-temperature impact.

4.9.1 Apparatus. —Cold chambers, at least 18 by 18 by 18 in., that open from the top are preferable. Dry-ice cabinets, cooled by circulated air and solid carbon dioxide, that are equipped with heater units perform well for this test.

The impact machine shown in figures 1 and 2 is constructed of cold-rolled steel except for the bolts, screws, and rubber stopper. All structural parts (i, e., base, anvil, arm, arm supports, and shaft) may be chromium-plated.

The arm including rubber stopper and bolt shall weigh 6 lb 13 oz, ± 1 oz.

Lubricants are not usually necessary. However, if lubrication is necessary, suitable low-temperature lubricants shall be used.

A 2- by 5 ¾-in. die; a good desk-type stapler with metal base, and stop mounted on base exactly ½ in. back of the center of the groove that turns the staple; 2- by 5-in. cards of regular 5- by 8-in. index-file-card stock.

4.9.2 Procedure.—The impact machine shall be in the cold chamber at −17.8° ± 2° C (0° ± 3.6° F) at all times. The temperature shall be measured in close proximity to the test specimen.

Ten specimens shall be cut with a die with the long dimension parallel with the transverse direction of the film or sheet. Each 2- by 5 ¾ in. specimen shall be cut and folded lengthwise with a normal loop at room temperature. The two ends of the folded specimen and one end of the 2- by 5-in. card shall be matched exactly, with the loop lying on the card. Two staples shall be crimped, ½ in. from and parallel to the 2-in. end of the stack.

The mounted specimens with loops up shall be placed in the cold chamber at the desired testing temperature for a conditioning period of 1 hour.

The card with specimen (after conditioning) shall be placed on the anvil with the crimped ends of the staples on the back of the card fitted into the groove in the anvil. (See fig. 2.) The card shall be handled, not the sample. The arm shall be allowed to fall free from a position within 5 degrees off perpendicular to the base. In order to facilitate this, a mechanical release device may be employed. The arm shall then be raised, the sample on the card shall be removed from the anvil, and the next specimen shall be positioned and struck, and so forth.

The removed specimen shall be examined for failure, which shall consist of breaking into two or more pieces.

4.10. Flammability.

4.10.1 Apparatus and materials.—The apparatus shall be constructed essentially as shown in figure 3 and shall consist of the following:

4.10.1.1 Specimen holder.—A removable, flat, specimen-holding rack, the upper and lower sections of which are separate, shall have the shape and dimensions shown in figure 4 (sketch of sample-holding rack.) The specimen is supported by tight closure of the upper and lower sections around the sides of the specimen. The center section of the rack contains an open U-shaped area in which burning of the specimen takes place. At the open end of the rack the forked sides are at an angle of 45° for the last inch. Thus, when the rack is slid into the cabinet on runners mounted at a 45° angle, the bent portion of the specimen adjacent to the igniter flame is vertical and the remainder is at 45°.

The switch actuators consist of suitable springs mounted on the side of the rack, one just beyond the curved portion at the open end, and the other at the closed end of the U-shaped holder. The springs are depressed and held in position prior to ignition by means of cotton thread suitably wound across the specimen and securely attached to the rack. As flame reaches these threads, the springs are released, thus activating the microswitches of the stop clocks.

4.10.1.2 Igniter flame.—The igniter flame shall be produced at the tip of a No. 22 hypodermic needle jet. The igniter shall be so located in the cabinet that the tip of the needle is ⁹/₁₆ in. from the surface of the specimen when the specimen rack is in place.

4.10.1.3 Cabinet.—The cabinet shall protect the igniter flame and specimen from air currents during tests, yet contain a suitable door or window for visual operation, provision for inserting the specimen holder, and adjustable vents to supply sufficient air for combustion of the specimen. It should also be capable of rapid ventilation following a test so that all combustion products can be removed between tests. A hood may be used if its exhaust fan is turned off during the test.

4.10.1.4 Timing mechanism.—The burning rate shall be determined by a stop clock through microswitches mounted on the specimen-holder rack. The clock is started when the specimen flame burns the first thread, and is stopped when the thread at the upper end of the holder, 6 in. from the first thread, burns apart. The timing mechanism shall be capable of indicating time interval to 0.1 second.

4.10.1.5 Butane. —Unless otherwise specified, butane gas shall be used for the igniter flame.

4.10.1.6 Thread.—J. & P. Coats heavy-duty white cotton thread.

4.10.1.7 Microburner.

4.10.2 Test specimens.

4.10.2.1 Test specimens shall be 3 in, in width and 9 in. in length. They shall be free from folds or wrinkles. Five specimens from each direction (machine and transverse) of a given material shall be tested.

4.10.2.2 Conditioning. —The conditioning procedure shall conform to the requirements of procedure B of ASTM D618, Tentative Methods of Conditioning Plastics and Electrical Insulating Materials for Testing.

4.10.3 Procedure.

4.10.3.1 After preparing the specimens, the holder shall be threaded so as to depress the switch actuators (springs) at least ¼ in. from the edge of the holder. Each actuator shall be separately threaded, the thread passing down through the J-slots and under the upper jaws so that the thread is adjacent to the specimen when the holder is closed.

4.10.3.2 The specimen shall be inserted into the holder so that it extends down into the lock springs and is held firmly between the two wires at the open end of the burning channel. These wires insure that the end of the specimen is always the correct distance from the igniter flame. The sample shall be free from wrinkles or distortion when the holder is closed. The specimen should not extend beyond the outer edge of the lower plate, otherwise the rack may not slide freely on the slide channel on introducing it into the cabinet.

4.10.3.3 Prior to introducing the specimen and holder into the cabinet, both electrical switches shall be set for automatic timing. The needle valve regulating the butane flow shall be adjusted to provide a ½-in. flame. (When the specimen is in place its surface is ⁹/₁₆ in. from the tip of the needle and the flame is just barely flattened against the specimen. This can be checked by using a specimen made of asbestos in place of a plastic specimen.)

4.10.3.4 With the hood fan off, clocks zeroed, and the flame adjusted as mentioned, the door is closed and the specimen holder is then inserted at a constant rate. The holder should be allowed to slide down the rails by gravity, taking about one-half second to travel the length of the slide. Any hesitation in bringing the specimen holder fully into burning position may cause erroneous ignition results.

4.10.3.5 The burning time shall be read from the stop clock and the rate of burning calculated. Results that deviate from the mean value of all tests should be rejected if the deviation of the doubtful value is more than five times the average deviation from the mean obtained by excluding the doubtful value. Such doubtful values shall be discarded and retests made.

5.1 Labels and literature. —In order that purchasers may be assured that the general purpose vinyl film actually complies with all requirements of this Commercial Standard, it is recommended that manufacturers include the following statement in conjunction with their name and address on labels, invoices, sales literature, etc.:

These (this) ____ comply (complies) with Commercial Standard CS192-53, as developed by the trade, under the procedure of the Commodity Standards Division, and issued by the U. S. Department of Commerce.

5.1.1 The following abbreviated statement is suggested when available space on labels is insufficient for the full statement:

Complies with CS192-53, as developed by the trade, and issued by the U.S. Department of Commerce.

5.2 Hallmark. —General purpose vinyl film may carry the hallmark shown in figure 5 to indicate compliance with this Commercial Standard.

6.1 Having been passed through the regular procedure of the Commodity Standards Division, and approved by the acceptors hereinafter listed, this Commercial Standard was issued by the United States Department of Commerce, effective from May 22, 1953.