TESTING OF BOPET, BOPP & METALLIZED JUMBO FILM SAMPLES

TEST - 1 Test : Average Thickness

Definition : Avg. thickness is the thickness of film over a particular length of film.

Scope : Average thickness is important to check whether film thickness is as per the required thickness or not.

Test Mehod : ASTM-D4138

Test Requirements : Cutter, scale, weighing machine

Test Procedure :

Measure 10 cm. film sample in MD direction. Cut the sample in TD direction. Measure width of sample in TD direction. Weigh the sample on weighing balance which is having capacity to measure upto 4th decimal.

Note down the weight in grams.

Avg .Thickness=Wt .∈gms¿¿

Precautions : Sample should be cut carefully. Weighing machine should be accurate upto four decimal places.

TEST - 2

Test : Tensile Strength & Elongation

Definition : Tensile strength is the maximum stress that a film can withstand while being stretched or pulled before failing or breaking.Elongation is the % increment in length of film before breaking.

Scope : Tensile properties determined by this test method are of value for the identification and

characterization of materials for control and specification purposes. The tensile modulus of elasticity is an index of the stiffness of thin plastic sheeting.

Test Method : ASTM-D882

Test Requirements : Tensile machine, computer for tensile machine, cutter, and template

Test Procedure : With the help of template cut the test specimen from the jumbo roll in such a way the specimen

from all the three sides (left, centre, and right) are obtained both in machine direction and transverse direction (MD/TD). Two specimens from each side and both direction shall be tested.

Ensure that that the test specimen should exactly 2.5 cm. in width. Fix the test specimen between the two gripping of machines which are exactly 10 cm. apart. Tight the gripping firmly to avoid the slipping of the film. Switch on the machine and continue the test till the sample break between the two grips.

Record the load at break. If the specimen which is failed in the grip shall be consider as premature failure and another

specimen shall be tested. Press the stop button at the time of break and note the extension reading and load from the dial

indicator.

Precautions : Sample strip should not have any shrinkage, scratch or cut. Sample should be placed properly in between two holders of machine. Edges of sample must be uniform by proper cutting.

TEST - 3

Test : Shrinkage

Definition :Shrinkage is the % reduction in the dimensions of a film undergone through high temperature.

Scope :This test is used to measurement of changes in linear dimensions of non-rigid thermoplastic sheeting or film that result from exposure of the material to specified conditions of elevated temperature and time.

Test Method : ASTM-D1204

Test Procedure : Cut a sample from jumbo roll with help of 10*10 inch template in such a way that the specimen

from all the three sides (left, centre, right) are obtained. Mark the MD & TD direction and record the dimensions. Hang the test specimen in oven set at :

I. 150 °±2 °C for 30 min (packaging grade)II. 200 ° ±2 °C for 20 min (yarn grade)

Check the temperature of thermometer before hanging the specimen being into ambient temperature from oven and record the dimensions.

% Shrinkage= X−YX

∗100

X – initial dimension of test specimenY – final destination (after oven)

Precautions :

Samples of three sides should be marked to avoid confusion. Care should be taken while using oven due to high temperature.

TEST - 4

Test : Haze

Definition : Haze is the cloudiness of a product that is caused by scattering of light. Haze is the percentage of light that is deflected more than 2.5 degree from the incoming light direction.

%Haze=T DiffusedTTotal

T - % Transmission

Scope :This test method covers the evaluation of specific light-transmitting and wide-angle-light-scattering properties of planar sections of materials such as essentially transparent plastic.

Test Method : ASTM-D1003

Test Requirements : Haze guard, cutter

Test Procedure : Cut at least three layers of film as per the size 100 mm * full width (TD) Place one specimen layer out of three layers previously cut at entrance point of sensing unit.

After that press the paddle for sensing the reading. While taking the readings note that no dust goes on the film & there are no thumb impressions, folded at the time of measurement.

The obtained value will be haze of the film, report max & min value. Take 5 to 10 from left to right.

Precautions : Three layers of sample must be taken so that middle layer can be used to test the haze of film. Initially machine must read zero haze so that no error can occur in test. Air must be avoided between film and machine glass.

TEST - 5

Test : Friction

Definition : Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other. Friction is of two types : static and dynamic. Static friction is more than the dynamic friction.

Scope :

Test Method : ASTM-D1894

Test Requirement : RDM test equipment, cutter, templates

Test Procedure : A piece of the test sample is held on the test bed by means of the vacuum channel so that the

film surface is flat, smooth and unscratched. Another piece of the same sample is cut using the template and fixed to under side of the sled

again using pressure sensitive tape. The sled is placed on the test bed. The sled is drawn by the drive mechanism for a distance at the constant speed required by the

test standard in use i.e. (15 cm/min). The force required to start the movement of sled is held by the digital display and is taken as a

static coefficient of friction. The force required to maintain movement of sled continuously measured by the load cell and

directly indicated on the force meter. This force meter reading during the sled travel is taken as kinetic coefficient of friction.

Coefficient of friction= AW

A – Force in gramsW – Sledge weight (200 gms.)

Precautions : Active load should be zero at starting. Film should be placed properly on machine by creating vacuum. Sample should be cut properly by using template. Two layers must be clean and do not have any scratches or cut.

TEST - 6

Test : Surface Tension

Definition :Surface tension is a contractive tendency of the surface of a liquid that allows it to resist an external force.

Scope :Surface tension is also an important property of film by the point of printability on the film. If the printing material got scattered on the film then printability is not possible on such film and complete film become waste.

Test Method : ASTM-D2578

Test Requirements : Solution of formamide and ethoxy ethanol

Test Procedure : Spread test fluid from the pen tip lightly over an area of approx. 7 cm sq. of the test specimen

noting the time it takes for the continuous film of ink to break into droplets. Wetting is normally adequate when a continuous film of test fluid remains intact for two

seconds. Breaking of fluid into droplets in less than two seconds indicates lack of wetting and a lower numbered test fluid should be tried.

If the fluids remain intact for longer than two seconds a higher numbered test fluid should be tried. The aim is to establish the lowest reading at an optimum dwell time of two seconds.

Extreme care must be taken to ensure the film surface is not touched or contaminated in the areas in which test are to be made.

It is recommended that when testing during production, the test fluid should be applied across the full web width and it should be noted that shrinkage of the liquid film on the sides of applied fluid does not necessarily indicates a lack of wetting.

Precautions :

Test should be started with proper value of test fluid. Check carefully that test fluid remain intact or not for two seconds.

TEST - 7

Test : Optical density

Definition : Dictionary meaning for the optical density is “ The degree to which a refractive medium retards transmitted rays of light” .

Optical density which is measured with the transmission densitometers is a representation of the materials light blocking ability and is calculated as the Log10 ( 1 / T) .

Where : T is the transmittance defined as P / Po P is the unabsorbed energy remaining in the light beam passing through the sample Po is the energy of the incident light beam

Scope : Transmission densitometers are traditionally used to evaluate the light transmission properties of a photographic film and same test is now used also to give an idea on the thickness of the aluminium layer of vacuum metalized films. Optical density provides estimation of the aluminium deposition on the substrate and hence the critical data for process control of the metallising process.

Test Method : Polyplex Method

Test Requirements : Heat sealing machine, strip cutting device (cutter).

Test Procedure : Cut a sample of standard dimensions with the help of template. Place the sample on place provided on transmission densitometer. Apply a unidirectional, perpendicular light beam is directed on the film sample. The light that is

transmitted through the film is collected, measured and logarithmically amplified.

Precuations :

TEST - 8

Test : Sealing Initiation temperature of BOPP film

Definition : Sealing initiation temperature is the temperature at which sealing of film just takes place. In other terms, it is the minimum temperature below which proper sealing will not take place.

Scope : Determination of minimum sealing temperature in BOPP film produced on line.

Test Method : PTM

Test Procedure : The specimen is taken in machine direction uniformly spread over the full width. If film has been

surface treated on one side the sides are to be marked correspondingly. Film strips of 25.4±0.1 mm width, greater than 170 mm length are cut by means of strip cutting

device or blade. At least 5 specimens per direction are to be tested. In case of one side film surface treatment a

minimum of 5 specimens per film side (untreated against untreated and treated against treated) and film direction should be tested.

The minimum width of sealing seam should be 10mm. Cut strips of 25.4 mm width, fold them and place between the sealing jaws in an angle of 90

degree. Before testing the film, sealing jaws should be preheated to testing temperature in closed

position for at least 30 min in order to obtain a constant temperature. Sealing condition are : pressure = 2 bar, time = 1 sec. Start the testing approximately 5 deg above the estimated minimum seal temperature and

reduce the temperature in steps of 1 deg. Record the minimum temperature at which the strips of film are sealed.

Precautions : Sample should be placed between the sealing jaws in an angle of 90°. Treated and untreated side must be marked before starting the test.

TEST – 9

Test : Sealing strength of BOPP film

Definition : Sealing strength of a film is value of load that has to be applied on the film upto just before the breaking of film.

Scope : Determination of sealing strength in BOPP produced on line.

Test Method : PTM

Test Requirements : Heat sealing machine, strip cutting device (cutter), tensile machine scale

Test Procedure : The specimen are taken in machine direction uniformly spread over the full width. If film has

been surface treated on one side the sides are to be marked correspondingly. Film strips of 25.4±0.1 mm width, greater than 170 mm length are cut by means of strip cutting

device or blade. At least 5 specimens per direction are to be tested. In case of one side film surface treatment a

minimum of 5 specimens per film side (untreated against untreated and treated against treated) and film direction should be tested.

Cut strips of 25.4 mm width, fold them and place between the sealing jaws in an angle of 90 degree.

The minimum width of sealing seam should be 10mm. Before testing the film, sealing jaws should be preheated to testing temperature in closed

position for at least 30 min in order to obtain a constant temperature. Sealing condition are : pressure = 2 bar, time = 1 sec. The specimens are to be clamped in a way to place the seam approximately into the middle of

the grip clamps and to prevent slipping of specimens in the clamps. The distance between the clamps shall be 100 mm. The speed of the drawing gripping clamp

shall be 100 mm/min. The projection strip end with the sealing seam should form an angle of approx. 90 degree

between seam and direction of tension during the measurement. Record the initial peak load as the sealing strength (gm/25 mm).

Precautions : Sample should be placed between the sealing jaws in an angle of 90°. Treated and untreated side must be marked before starting the test. Open seal strength file in computer for tensile machine before starting the test.

TEST – 10

Test : Gloss of BOPP film

Definition : Gloss is the property of shining of any surface.

Scope : Determination of % gloss in BOPP film produced on line.

Test Method : ASTM-D2457

Test Requirements : Gloss meter of 45° angle geometry, template and blade.

Test Procedure : Specimens are taken uniformly from film web. Specimen with visible direction on the surface or

notches at their edges or corners will not be tested and free from creases, wrinkles and dust. Cut three specimens each from left, right and centre of around 10 x 10 cm2 . Ly on the sample on standard gloss sheet one by one. Put the gloss meter on the sample. Do calibration by CALIBRATION MODE and then SAMPLE MODE. Note down the value of gloss.

Precautions: Do not touch surface of millitron on which sample is to be placed. Set initial reading of millitron at zero.

TEST – 11

Test : Transmittance

Definition : Transmittance is the fraction of incident light (electromagnetic radiation) at a specified wavelength that passes through a sample. Transmittance tells about the amount of light which has been passing through the film.

Scope : Determination of value of transmittance of BOPET & BOPP line produced at the line.

Test Method : ASTM-D1348

Test Requirements : Haze guard, cutter

Test Procedure : Cut at least three layers of film as per the size 100 mm * full width (TD) Place one specimen layer out of three layers previously cut at entrance point of sensing unit.

After that press the paddle for sensing the reading. While taking the readings note that no dust goes on the film & there are no thumb impressions, folded at the time of measurement.

The obtained value will be transmittance of the film, report max & min value. Take 5 to 10 from left to right.

Precautions : Three layers of sample must be taken so that middle layer can be used to test the haze of film. Initially machine must read zero haze so that no error can occur in test. Air must be avoided between film and machine glass.