UNIT 1.

UNIT 1

OVERVIEW OF PRESENTATION
INTRODUCTION OVERVIEW OF PRESENTATION WHAT IS PAPER? WHAT IS PAPER MACHINE? WHAT ARE THE PROBLEM,S OCCUR ON PAPER MACHINE? ORIENTATION OF FIBER MACHINE AND CROSS DIRECTION EFFECT OF WIRE AND FELT SIDE

WHAT IS PAPER? PAPER IS THE WEB OF FIBERS WHICH IS IREGULARLY INTERWOVEN WITH EACH OTHER. RANDOM NETWORK OF CELLULOSIC FIBER WHICH IS FORM ON PAPER MACHINE.

WHAT IS PAPER MACHINE? PAPER MACHINE IS THE DEVICE ON WHICH OR PAPER GET FORM 0N IT . IN PAPER INDUSTRY PAPER MACHINE IS CALLED HEART OF PAPER INDUSRTY. ON IT MANY ROLLS AND OTHER INSTRUMENTS LIKE HEADBOX, PRESS PART, DRYERS,CALENDERS,SIZE PRESS ARE PRESENT WHICH HELP TO FORM BETTER QUALITY OF WEB ON IT.

PROBLEM OCCUR ON PAPER M/C DURING WEB FORMATION
TWO SIDEDNESS VARIATIONS IN PAPER M/C CAUSE VARIATIONS IN PAPER PROPERTIES AFFECT THE APPEARANCE IF DIRT PRESENT IN SURROUNDING OF PAPER M/C AND MANY MORE

ORIENTATION OF FIBER WHAT IS FIBER?
FIBER IS DEFINED AS THE SINGLE HAIR LIKE STRUCTURE WHICH COBINES TO FORM WEB OVER PAPER M/C ON PAPER. THE GREATER ORIENTATION OF FIBER IN DIRECTION OF TRAVEL OF THE PAPER M/C. THE GREATER ORIENTATION WHICH RESULT PARTIALLY FROM THE GREATER FIBER ALIGNMENT AND PARTLY FORM THE GREATER TENSION EXERTED ON THE PAPER IN THIS DIRECTION DURING DRYING.

CONTINUE THE ORIENTATION OF FIBER ARE GREATER IN M/C DIRECTION AS COMPARE TO CROSS DIRECTION ALL THE PROPERTIES EITHER PHYSICAL CHEMICAL OR OPTICAL ARE AFFECTED AND RELATED TO THE ORIENTATION OF THE FIBER. A NEW METHOD FOR MEASURING THE DEGREE OF FIBER ORIENTATION IS BY X RAY. THIS METHOD IS BASED ON THE FACT THAT THE MAJORITY OF THE FIBRILLS ARE LINNED UP IN THE FIBER DIRECTION AND HENCE PRODUCE AREA IN X RAY DIAGRAM WHICH INDICATE THE POSITION OF FIBER IN PAPER.

EFEECT OF WIRE AND FELT SIDE ON PAPER
PAPER HAS 2 SIDES THE WIRE AND THE FELT SIDE . THE WIRE SIDE IS THE SIDE OF THE PAPER WHICH IS IN THE CONTACT WITH WIRE AT THE TIME OF THE SHEET FORMATION. THE OTHER SIDE IS FELT SIDE. WHICH IS NOT IN CONTACT WITH WIRE. THE WIRE SIDE IS ROUGHER DUE TO PATTERN CAUSED BY WIRE MARKS. PAPER IS GENERALLY OPEN ON THE WIRE SIDE AND CLOSED OR FINER TEXTURED ON THE FELT SIDE.

CONTINUES ALL THOUGH ALL THE PROPERTIES OF PAPER ARE AFFECTED BY THE FORMATION OF THE FIBER BUT SOME OF THEM ARE SMOOTHNESS (MORE IN FELT SIDE) POROSITY (MORE IN WIRE SIDE) FORMATION (BETTER IN FELT SIDE THAN IN WIRE SIDE) GLOSS AND BRIGHTNESS (MORE IN FELT SIDE) INK ABSORBENCY (MORE IN WIRE SIDE)

MACHINE DIRECTION AND CROSS DIRECTION
THE DIRECTION OF THE PAPER IN THE DIRECTION OF THE TRAVEL OF THE PAPER MACHINE IS CALLED MACHINE DIRECTION. OR THE GRAIN DIRECTION IS KNOWN AS MACHINE DIRECTION. PERPENDICULAR TO THE MACHINE DIRECTION IS KNOWN AS CROSS DIRECTION. THE PROPERTIES WHICH ARE AFFECTED BY THE MACHINE DIRECTION AND BY THE CROSS DIRECTION ARE AS FOLLOW

M/C DIRECTION AND CROSS DIRECTION

CONTINUE TENSILE STRENGTH (GREATER IN THE MACHINE DIRECTION)
FOLDING STRENGTH (GREATER IN M/C DIRECTION) TEARING STRENGTH (GREATER IN CROSS DIRECTION) STIFFNESS (GREATER IN THE M/C DIRECTION) BASIS WEIGHT (GREATER WEIGHT VARIATION OBSERVED IN THE CROSS DIRESS DIRECTION THAN IN MACHINE DIRECTION)

UNIT 2

BASIS WEIGHT DEFINITION :- The weight of paper per unit area is defined as basis weight. This can be expressed as weight in grams per square meter (GSM) This can also be expressed as the pounds per 1000 sq. ft.

Generally paper is sold on weight basis
Generally paper is sold on weight basis. Also paper is defined as per unit of area rather than per unit of volume. The area is more important than volume as paper is used in sheet form.

INSTRUMENTS FOR MEASURING BASIS WEIGHT
QUADRANT SCALE a. Quadrant type ( Thwing ) b. Pendulum type ( Schopper ), ( Cady ) c. Lever type ( Toledo )

QUADRANT SCALE

QUADRANT SCALE Quadrant scale is a specially graduated scale which give the result directly in gram per meter square. Sample size of paper is 40*25cm2. The template size is 20*25 cm2.

2. β-RAYS BASIS WEIGHT GAUGE
It is an interesting new device for measuring the basis weight of paper continuously and automatically in β-rays basis weight gauge. The paper absorb β-rays in direct proportion to it’s mass so that the response of the detector to the rays passing through the paper is the function of the basis weight. The paper travel through a measuring head which consist of a β-rays emission chamber below the sheet and an ionization chamber above the sheet that detects the desired weight.

Sample conditioning standards
Time = 4 to 12 hr. ( for normal paper ) Relative Humidity = 50 % Temperature = 23 ± 5°C For certain treated paper and heavy paperboards may require 24 to 48 hours for conditioning till constant weight is obtained.

Basis weight of different grades of paper
Tissue paper GSM News paper GSM Cigarette paper GSM Writing – printing GSM Paper board GSM Board GSM

THICKNESS/CALIPER Caliper or Thickness For a given basis weight, determines how bulky or dense the paper is. A well beaten/refined pulp, short fiber pulp such as hard wood or straw pulp, highly filled or loaded paper will show lower thickness for given basis weight. Thickness or Caliper of paper is measured with a micrometer as the perpendicular distance between two circular plane parallel surfaces under a pressure of 1 kg/ 𝑐𝑚 2

Thickness affects nearly every physical, optical & electrical property of paper. It is highly important in case of filling cards which should not exceed the required thickness avoid taking up variable space in filling cabinet. Thickness is important in case of book paper, since it affect the opacity of paper and amount of impression received on printing press. A typical 80 pound coated book paper will normally caliper about inch with a variation of about inch.

CALIPER MICROMETER

Thickness is factor in the performance of condenser paper, bloating paper, wrapping paper and many other paper grades. Capacitor paper is made to specification of to 10000’s of an inch ± 11 hundred tolerance. Craft linear board is sold on the basis of caliper and there for it is important in the mfg. of this grade to maintain maximum caliper consistent with the desired physical properties.

Caliper is also very important in folding book board where it is the most important variable affecting thickness. The thickness gauge tends to ,measure the thickest part of the paper because of the relatively large diameter of the micrometer (1/4 inch). The measured caliper usually higher then the actual caliper because the anvil of the thickness gauge tends to bridge over the high spots of the paper this can result in a substantial difference between measure and true value in the case of rough finish paper board.

Burst and bursting strength
Rupture of the paper is called burst 2. Bursting strength-- Bursting strength of material is defind as the maximum Hydrostatic pressure required to Produced rupture of the material . When a controlled and constantly increased pressure is applied through a rubber diaphragm to a circular area, 30.5 mm dia.

3. Scope-- This method is designed to measure the max. bursting strength of paper and paper product having bursting strength of 50 KPA up to 1200 KPA and in the form of flat sheet of up to 0.6 mm thick. It is not intended for use in testing fiberboard linearboard, hardboard that tend to cut the thin rubber diaphragm of the bursting tester.

4. Unit-- 5. APPARATUS-- 1. Pounds per square inch
1. Mullen Bust tester 2. Caddy 3. Ash croft 4. Schopper Dolen

6. Factor affecting bursting strength
1. Fiber length, inter fiber bonding. 2.increase beating, Increases the bursting strength. 3. Surface sizing affects the bursting strength.

7.Procedure The specimen should be held b/w two annular clamps under sufficient pressure to minimize slippage. The sample is clamped b/w the lower clamping plate and pressure cylinder so that before the paper sample is stretched by pressure underneath. The paper starts to rupture when pressure is applied. Note the reading at that point when paper is ruptured.

8. Uses of bursting strength-- 9. Burst factor--
1. It is quite important in bag papers. 2. It is important in wrapping papers. 9. Burst factor-- Burst strength in gm/cm² per Substance in gm/m²

10. Density Density related to the porosity, rigidity, hardness strength of the paper. Unit= kg/m³ Density formula ( Basis wt. In GSM/Thickness in cm) Relation between density and sheet property Clark found that burst and tensile strength are linearly perportional to density. Density greaterly effect the optical properties. Inc.beating has no effect on tensile strength. Filler Increase The density but Decrease the strength

11.Factor affecting density
1.Density which is obtained as the ratio of weight the thickness before paper furnished to remove surface irregularities 2.In the case of box board there is a true Density with increase in caliper

A PRESENTATION ON POROSITY AND FORMATION
PAPER PROPERTIES A PRESENTATION ON POROSITY AND FORMATION

Porosity In the following presentation paper porosity actually means air permeability. A measure of the extent to which a paper surface will allow the penetration of a gas or liquid, such as air or ink, through its surface. The nature of paper is such that the bonding of the paper fibers produces many tiny air passages through out the paper, which can either be completely submerged in the paper.

Porosity can be measured in the laboratory or online on the paper machine.
In the following, the measurements are air flow values like in Bendsten (ml/min) or time values for a constant air volume like in Gurley(s). Notice that a smaller number in seconds means a higher air flow and porosity. sizing ,coating ,calendaring and super calendaring all also work to seal and/or compress surface fibers, reducing the paper's porosity.

If the air-permeability of the paper is too high (i. e
If the air-permeability of the paper is too high (i.e. low Gurley Densometer value).Papermakers know intuitively that they can solve this problem by greatly increasing the basis weight.

Online Porosity:- The latest online porosity analyzer has a strong and durable structure avoiding mechanical damages during machine breaks. The sensing element is specially coated to minimize friction, dusting and dirt build-up on the web contacting surface.

The units of porosity is ml/min. Instruments :-
Bend ten smoothness and porosity tester. Gurley densometer. Williams tester. Permeometer

MEASUREMENT:- In routine paper testing porosity is generally measured by the resistance of paper sample of given dimension to the passage of air under standardized condition of pressure, temperature, and relative humidity. This resistance is measured by Gurley or SPS tester. This tester measured the time of flow of the standard volume of air (usually 100cc) through a standard area (usually 1sq. in.) of the paper under uniform light pressure. Air is forced through the paper by pressure resulting from the weight of the inner cylinder floating freely in an outer cylinder partly filled with light oil

In densometer paper is clamped on the top of the inner cylinder, whereas the paper is clamped on the base of the SPS tester on the top of a perforated plate. The instruments are equipped with an elastic rubber (Thiokol) gasket to prevent air leakage laterally across the surface of paper. This gasket is a part of the densometer but must be inserted in the SPS tester when porosity test are being made. The moveable inner cylinder is graduated in units of 50ml, the volume air transmitted is read on the gage. The time for the passages 100cc of air is taken after the cylinder has been released and attained a steady downward movement. The apparatus should be tested periodically for leakage by testing smooth, non – porous material such as metal foil: leakage exceed 10ml of air per hour.

POROSITY OF VARIOUS GRADES OF PAPER
S NO. PAPER GRADE POROSITY (In ml/min.) AVERAGE of POROSITY A B C D 1 WRITING AND PRINTING PAPER 160 140 150 152.5 2 PHOTO COPY PAPER 280 260 310 282.5 3 DRAWING PAPER 1100 1150 1087.5 4 NEWS PAPER 295 300 292.5

Importance of Porosity
Porosity is a paper property of direct importance in writing printing paper, since it is a factor in absorption of ink. It is definitely related to oil resistance and hence is an important property of grease an proof and oil resistance paper. Porosity is an extremely important property of saturating papers. Porosity is very important in bag papers, filter paper. It is an important property of coating of a raw stock for pigmented coated papers where it affects the adhesion of adhesive.

Fig:-Bendsten Smoothness And Porosity tester

Formation:- The manner in which the fibers of a sheet of paper or board are distributed, disposed and intermixed to constitute the sheet. Formation is an indicator of how uniformly the fibers and fillers are distributed in the sheet. Formation plays an important role as most of the paper properties These will affect properties like caliper, opacity, strength etc. Paper formation also affects the coating capabilities and printing characteristics of the paper.

Paper formation also affects the coating capabilities and printing characteristics of the paper.
A poorly formed sheet will exhibit more dot gain and a mottled appearance when printed. There is no standard method or unit to express formation However when holding paper up to alight source, a well formed sheet appears uniform while a poorly formed sheet has clumps of fibers giving a cloudy look. It is physical property of paper. Formation is affected by the transparency of the paper since in general the more transparent the paper, the more readily poor formation shows up. for ex. Wax paper generally appear more poorly formed than the same paper.

MEASUREMENT OF FORMATION:-
An instrument consisting of a photo electric cell which scans the under Neath side of the paper. While a small beam of control intensity is projected on the upper surface of the paper the paper is moved at high velocity through the tester. So that the amplitude and frequency of variation in transmitted light can be measured by the photoelectric cell.

Smoothness and dirt, fines. Presented by

Smoothness Introduction
Smoothness is concerned with the surface contour of paper. It is related to gloss because both gloss and smoothness are affected by calendering, but the two properties are not the same .

Defination of smoothness
Measure of the evenness or lack of contour of a paper's surface. In terms of basic printability, a surface as free It is most important parameter for printer. Smoothness is concerned with the surface contour of paper. It is the flatness of the surface under testing conditions which considers roughness, levelness, and compressibility.

Factor affecting smoothness
1.Increased beating of the stock increase paper smoothness . 2.The type of wire and weave of the felts used on the machine also affect smoothness . 3.Increased wet pressing and increased calendering improve the smoothness. 4.Filling improves the smoothness, particularly after calendering. Surface sizing is improves smoothness.

The biggest factors affecting smoothness of
paper tend to be mechanical, rather thanchemical In particular, the type and extent of calendering usually causes the largest change in paper smoothness and density as the sheet passes through the system

Importance of smoothness
1.Smoothness is related to the appearance of paper because, as a general rule, a rough paper is unattractive. 2. Paper with excessive wire and felt marks or paper that is lumpy , fuzzy , or badly crushed is considered unsatisfactory. On the other hand, small evenly distributed irregularities often give a pleasing appearance of pattern or texture.

Practical details 1. Aim : To find out the smoothness of a given paper smple. 2. Apparatus : bendsten smoothness and porosity tester. 3. Scope: surface smoothness has an important influence on the printing quality. Smoothness also affects properties such as the co-efficient of friction, gloss and coating absorption.

Methods for measuring smoothness of paper
Airleakage method Profilometery method Optical contact method

SPS Bendsten apparatus

4. Procedure: 1) Apply the monostate wt. (usually 150mm awG) in place .Set the changeover the cock to lower the position. 2) Switch on the instrument and place the smoothness gauge on the glass plate carefully and the rotar in all the three Rotameter tubes must give zero readings or reading given by the float in the first Rotameter should be note down and Afterwards to be subtracted from the actual value

3) Place the test specimen upon the precision plane - glass plate and place theSmoothness gauge on top of the paper .The gauge is placed by light hand without Pressing 4) Determine the air flow escaping between the paper and the thin using of the guage. From the rotameter perform the test at least in four places of the test specimen from each side of the paper.

Table for Smoothness of different grades of paper
Sr. No. Different grades of paper Smoothn ESS of Different . Paper A B C Average 1 Newspaper 240 220 2 Blotting paper 2500 2550 2400 3 Filter paper 2100 2150 2200 4 Writing and printing paper 320 260 280 286.67

Fines When papermakers say the word "fines" they may be talking about just "fiber fines," or they may be referring to everything solid in the furnish that is small enough to pass through a screen.

When papermakers say the word "fines" they may be talking about just "fiber fines," or they may be referring to everything solid in the furnish that is small enough to pass through a screen. Though researchers tend to define "fines" in terms of a standard sieve size, papermakers usually will consider something to be a fine if it can pass through the forming fabric used on that machine.

Sometimes the term "fine particles" is used to make it clear that one is including such items of clay or calcium carbonate filler within the description.

Function - Fiber fines, in general terms, tend to contribute to the smoothness and resistance to air penetration through paper. A moderate content of fines, e.g. up to about 10 to 35%, often achieves maximum strength, depending on the type of furnish and the quality of the fines. Fiber fines tend to impede dewatering throughout the papermaking process.

Strategies for Use: When they get desperate, papermakers occasionally will sewer their fines. But, when they can, they would much rather add the weight of the fines to what they sell to their customers. It often comes down to a question of finding a way to retain the fines well, without hurting the uniformity of the sheet.

And it comes down to a way of overcoming the drainage problems associated with high fines levels. Conventional drainage aid strategies, retention aid programs, and micro-particle programs can be very effective

Dirt in paper as paper defects
Failure to meet the specification for any paper property could be considered a paper defects; however in normal usage the term " paper defects" refer to some unwanted characterstics that is not normal property of paper.

Defination of dirt Dirt is defined as foreign matter embedded in the sheet which has a marked contrasting color to the rest of the sheer and which has equivalent black area of 0.04mm2 or more.

Demerit of dirt in paper
Dirt in a paper is one of the most common defects. Dirt gives paper an unsatisfactory appearance. Dirt is particularly offensive in writing and printing papers and in the higher grades of wrapping paper .

Measurement of dirt Dirt is determined by coumting the number of specks in a given area and estimating the equivalent black area of the apecks. Standard comparison charts that have a series of black spots of different areas on a white background are used for estimating the equivalents black area of each spot.

Total dirt count depends on
The type of light used for examining the paper The type of dirt specks

Sources of dirt The pulp supply is generally the greatest sources of dirt. The type of dirt indicates the source. Very small dirt particles of a woody nature in the range of 0.01 to 0.1mm2 indicates the wood cleaning operation in the pulp mill nor be satisfactory .

Measurement of dirt Dirt is determined by coumting the number of specks in a given area and estimating the equivalent black area of the apecks. Standard comparison charts that have a series of black spots of different areas on a white background are used for estimating the equivalents black area of each spot.

Total dirt count depends on
The type of light used for examining the paper The type of dirt specks

Sources of dirt The pulp supply is generally the greatest sources of dirt. The type of dirt indicates the source. Very small dirt particles of a woody nature in the range of 0.01 to 0.1mm2 indicates the wood cleaning operation in the pulp mill nor be satisfactory .

STIFFNESS AND TENSILE STRENGTH OF PAPER

Stiffness Definition: - -Stiffness is related to flow properties because it depends upon the ability of the layer on the outside curve of the material to stretch and on the ability of the curve to undergo compression units:- The unit of stiffness is Taber.

INSTRUMENTS Taber instruments Gurley instruments Handle-o-meter
Pierce tester Tinius olsen tester Static banding method

MEASUREMENTS In Taber instrument, a specimen is fastened in a clamp pendulum. .Load is applied to the lower end of the specimen by rollers attach to a power driven disk so that the resulting torque deviates the pendulum from the vertical. The end point is indicated by the allignment of the pendulum with the 15degree mark on the loading disk. .In carrying out of the test, the force should be applied slowly and the average of the deflection taken for both directions.

STIFFNESS TESTER

FACTORS AFFECTING STIFFNESS
Stiffness off paper is greatly affected by thickness of paper theoretically as the cube of thickness .Paper made from highly beaten stocks (bond and glassine) have higher stiffness than paper made from lightly beaten stocks (toweling and filter paper). Papers made from pulp high in hemicellulose content (e.g.; straw pulp) are stiffer then paper made from long fibered pulps.

Paper made from chemical wood pulp has higher stiffness to tear ratio than do rag paper.
Stiffness is important in folding boxboard since the utility box depends upon its ability to resist bulging when filled. .Moisture is also affects the stiffness greatly. .Stiffness increases with amount of beating.

IMPORTANCE OF STIFFNESS
Stiffness is of very great importance in index bristol’s, card middles, typing paper, and playing card, where the paper must stand right during use. .A certain amount of stiffness desirable in box paper where it is a factor in the handle of the paper. Stiffness is very important in corrugating medium for corrugating board.

TENSILE STRENGTH Definition:-Tensile strength is a measure of the resistance of paper to direct tension. It is defined as the force required to break a strip of paper which has specified dimensions. .Units:- The units of Tensile strength is Newton (N) Instruments:-Zero span tensile strength tester.

MEASURMENTS The zero span tensile strength tester use a pendulum for applying load, which is free rotate in a vertical plane. .The paper is clamped between two (both which moves during the period of applying load), and then pendulum is swung out from its vertical resting position by the hand motor. .This applies an increasing load to the paper until finally the strip breaks. .The load at which the strips breaks is termed the tensile strength and is reported in kg for 1.5cm of width, or in pound per inch of width.

TENSILE STRENGTH TESTER

FACTORS AFFECTING TENSILE STRENGTH
Tensile strength of paper is always in M.D. than in C.D. because of the greater alignment of fibres in the M.D. .Increasing the weight of paper increasing tensile strength. .The amount and quality of fibre bonding is also most important factor affecting stiffness?. The tensile strength is proportional to square root of the average fibre length weight.

IMPORTANCE OF TENSILE STRENGTH
Tensile strength is important in newspaper and other papers printed on web press where high tensile strength helps to resist web breaks. Tensile strength is important property of bag and wrapping papers. .High tensile strength is needed in asphalt saturated papers to resist the stresses set up when the rated paper is festooned during drying. It is particular important in gummed paper, spin paper, binder twin and cable paper.

Tearing strength & breaking length of paper (Group no. 7)

A.)Tearing resistance (tearing strength)
Definition:- Tearing strength is a measure the amount of work done in tearing the paper through a fixed distance after the tear has been started by means of a cutter attached to the instrument. Tearing resistance/ strengths is the ability of the paper to withstand any tearing force when it is subjected to. It is measure in both MD & CD, expressed in mN (mili Newton).

Fig- Elmendorf tear tester.
UNITS:- The unit of tearing strength is milli newton (mill N). INSTRUMENT:- Fig- Elmendorf tear tester.

Measurement In this tester the specimen is clamped (2
Measurement In this tester the specimen is clamped (2.5in,63mm) between two clamps, one of which is stationery and other of which attached to pendulum. An initial slit is cut in the specimen, leaving 1.69in (43mm) of paper to be torn by the instrument. The pendulum is released, and the specimen is torn in two as the clamp in the pendulum moves away from the fixed clamp. As the paper is torn the work is done on it. The work done is measure by difference in

potential energy of the pendulum at the beginning and end of swing
potential energy of the pendulum at the beginning and end of swing. The angle is measured by a pointer mounted on the same axis as the pendulum. The angle is measured by a pointer mounted on the same axis as the pendulum which has a constant friction just sufficient to stop it at highest Point reached by the swing of the sector when there is no paper in tester. Tearing strength in some time report as tear factor by dividing the tearing strength in gram (per single sheet) by the basis weight in gram per square meter. It is also reported as tear ratio, or tearing strength in points (gram) per pound. .

Formula used Tearing factor = tearing strength × 20.4 Basis weight
(For 4 sheets) Tearing factor = tearing strength × 40.8 ( For 2 sheet ) Tearing index = tearing factor × 9.81

Factor affecting tearing strength
The total number of fiber participating in the sheet rupture. The length of the fiber. Number and strength of fiber to fiber bonds. After a slight amount of beating, inter fiber bounding is increase and the tearing strength is greater because of the increased frictional resistance in pulling fibers out of the paper. Fiber length is very important factor in tearing strength Tearing strength increases with increase in fiber length.

Clark, states that tearing strength is increase according to the square root of the average fiber length. Tearing strength is higher on unstrained paper than on strained paper because of the extra work required to straighten out the fibers unstrained fiber.

Importance of tearing strength
The tear test is particularly use full in the evaluation of bag, tag, wrapping paper, building tissue, certain grades of boxboard, and another grades of which are subjected to tearing strain in use. It is probably the best test, although still inadequate for measuring the ability of paper in web form to stand up to stresses imposed by running roll.

B.) Breaking length Definition :-- It is the length of paper strip, if suspended vertically from one end, would break by its own weight. Breaking length is generally used in the paper trade to characterize the inherent strength of paper. It affords an excellent basis for comparing the strength of papers made from different furnishes and having different basis weight.

Tensile strength:-- The maximum tensile force per unit width developed in a test specimen at rupture or break under prescribed conditions. The tensile force required to produce a rupture in a strip of paper or paperboard, measured in MD & CD, expressed in kN/m. Tensile strength is indicative of fiber strength, fiber bonding and fiber length. Tensile strength can be used as a potential indicator of resistance to web breaking during printing or converting.

Unit :-- The unit of breaking length is m or km
Unit :-- The unit of breaking length is m or km. Instrument:-- vertical electronic tensile teter or zero span tensile tester.

Measurement Sampling :- cut five test specimen in each prinicipal direction of the paper , 15 mm wide with the side parallel with in 0.1 mm and long (15cm) enough to be free from water marks , abnormality, cut edges , creases,wrinkles etc. Switch on the the instrument . Press on switch . Watch the check value . If the value =0 then OK. If not then ,adjust 0 be rotating the zero knob.

Check the sample span length and adjust if required by pressing the knob of gauage length . Check the pulling speed of the lower jaw by pressing the knob and adjust the speed knob by increasing or decreasing. Insert the sample into the jaw of a particular tensile direction ,after performing test press TEST button . Note down the tensile force and elongation in MD And CD. By this reading we calculate the breaking length of paper.

Formulas used Braking length = tesile force in newton × 6800
AC gsm of paper Breaking length = tensile strength × Basis wt. Of paper Tensile Strength =tensile force ×length of strip Wt of papaer

Factor affecting the breaking length of paper
The amount and quality of fibre bonding is also most important factor affecting stiffness? Breaking length of paper is always greater in M.D. than in C.D. because of the greater alignment of fibres in the M.D. Inter fibre bonding Bwtween the fibres .

Important of breaking length for some papers
Tensile strength is important in newspaper and other papers printed on web press where high tensile strength helps to resist web breaks Tensile strength is important property of bag and wrapping papers.High tensile strength is needed in asphalt saturated papers to resist the stresses set up when the rated paper is festooned during drying. It is particular important in gummed paper, toweling paper ,creped paper and cable paper.

A FOLDING ENDURANCE AND HARDNESS IN PULP AND PAPER INDUSTRY

DEFINITION OF FOLDING ENDURANCE
DEFINITION : Folding endurance is an empirical test which measures the amount of folding endure before its tensile test . UNITS : It is generally measured in number of folds . INSTRUMENT : 1) Schopper ) Kohler Molin

MEASUREMENT OF FOLDING ENDURANCE
In MIT paper the strip of paper clamped between spring loaded clamped and an oscillating folding head . The oscillating head folds the paper to the right and left through a total angle of 270 degree at a rate of about 175 double folds per minute . The Kohler Molin is more versatile instrument than the Schopper ,since latter is limited to paper having thickness no more than 0.01 inch , where s the Kohler handles the paper of widely varying thicknesses by using different jaws .

FACTOR AFFECTING FOLDING ENDURANCE
Higher tensile strength in the M.D indicates that some flexibility or flow property is involved in the folding endurance . Higher tensile strength in the M.D indicates that some flexibility or flow . As a general rule folding endurance increases with increases basis weight upto certain optimum after which it further increases in weight lower fold . Fold endurance increased with increased in sheet thickness .

Lack of folding endurance can be result of lck of fiber length .
Plasticizer increases folding endurance of paper by reducing the stiffness .

IMPORTANCE OF FOLDING ENDURANCE
It is particular importance in measuring the quality of high grade sulfite and rag content bond, ledger, currency, index, cover, map, blue print and recorded paper . The folding endurance test is particularly useful for measuring deterioration of paper upon ageing . the fold test is based upon the fact that is the test means of measuring quality of those papers which are required to resist considerable handling nd folding in use .

HARDNESS DEFINITION : Hardness is the property of paper that causes it to resist indentation by other material . Hardness is also used in reference to pulps to denote the degree of delignification . RELATION OF HARDNESS TO OTHER PROPERTIES : In general, hardness follows the density of the paper, and consequently papers that require a high degree of hardness should be made from easy beating pulps .

A high moisture content lowers the hardness of paper .
Hardness is the most important properties that influence the printing qualities of paper since it effect the ease with which the printing plate establishes contact with the paper surface . In printing, the softer the paper, the better the contact with the printing plate . Surface hardness is desired in some papers (e.g. boxboard and writing printing papers) , and these are usually surface treated with starch or glue .

Dimensional stability
Curl & cockling

Dimensional Stability
The change occuring in the dimension of paper with change in the moisture content in an important consideration in the use of paper All paper expand with increasing moisture content and contract with decreasing moisture content, but the rate of change extent of change vary with different paper

Instrument for measuring dimensional change
Most of the instrument for measuring dimensional change of paper with change in moisture content A measuring devices indicates the length of paper strip before and after conditioning. The indicating devices used for measuring the expension include direct reading dials,curved scales, magnifying lever arrangement and magnifying glasses,

Paper requiring dimensional stability
Some of the grades of paper requiring a high degree of dimensional stability are printings papers, map papers, template papers. Aluminium mounted papers are some time uses in making map papers where expension must be held to a minimum.

Fiber and sheet characterstics affecting dimension stability
Dimension change in paper due to two factors:- Fiber swelling the contaction (or swelling ) of individual fiber. Dipersion swelling the drawing together (or a pulling apart ) from of the fiber. Dimensional stability is affected by the fiber composition.

Curl & Cockling Curl is a problem closely related to dimensional stability There are curl several forms of curl :- Curl to the wire side of the sheet, curl to the felt side of the sheet and curl partly to the wire side and partly to the felt side.

Types of curls There are four types:-
Inherent curl,which is bullet into the paper and so up immediately. De-Layed curl,which is roughly the same as inherent curl but so up on aging. Structural curl,which is caused by physical difference into the two surface of the paper. Moisture curl,which the result of dimensional change caused by change in moisture content.

Test for measuring curl
The maximum curl which a given paper will undergo in sometime measured in the carson curl tester. A test used in some laboratory to measure curl is to dry out a sample of paper strp form and means the curl which take place.

Factor affecting the curl
Curl is more pronounced with thin than with thick paper,because they have less resistant to curl. Paper made from long,highly beaten fibre are more likely to curl than paper made from short. Bleached pulp are reported and produced more curl than unbleached pulp. Rosin-sized paper seem to curl more than unsized paper.

Cockling Cockling is caused by irregular shrinkage in drying.
Cockling can be attributed to local variations in basis weight, moisture content, density or other paper ties of the paper upon living the paper machine which result in local bullet in strain in paper.

Stress - strain curve of paper
Much can be learned about paper strength and the contributions of various fundamental factors related to strength by a study of stress-strain relationship found in paper. Before discussing the stress-strain relationship of paper. It is desirable to define what is means by stress, strain, ideal elastic solids and ideal liquids. Stress:- It is the internal force per unit of area (newtons per square meter or pounds per square inch) that resists the external load. Strain:- It is the ratio of change in dimension to the original dimension.

Ideal elastic solids deforming instantaneously under applied load to a degree linearly proportional to the load and returned to their original dimension when the load is removed. Elastic limit:- It is the maximums tress that the specimen will bear and still return to its original shape. Paper exhibits (1) a nonlinear load- elongation curve. (2) a continuing extension of creeping under constant load. (3) a load- elongation curve that varies with the rate of loading (at high rates of loading the breaking elongation degrease and the breaking load increases) (4) a tendency for the load required for a constant elongation to decrease with time. Paper can show an immediate elastic effect, a delayed, elastic effect (recoverable) and a delayed nonrecoverable elongation.

Instruments for Measuring Stress-Strain:-The pendulum-type ensile tester is not suitable for measuring the stress-strain relationship because of us low degree of accuracy and its complexity (neither stress not strain is applied at a constant rate), and became the specimen is ruptured during the test. Steenberg has described suitable apparatuses for measuring the stress-strain properties of paper. To types of apparatus are used, one for slow rates of loading and one for very rapid rates of loading. Typical stress-strain curves for relatively still, brittle paper (tested at 20 percent relative humidity) and relatively plastic paper (tested at 98 percent relative humidity) are shown in figure on the basis of measurement made with the slow instrument.

The instron tester is widely used to measure the stress-strain relationship.
The upper jaw is attached to a strain gauge that measures the stress on the paper as the lower jaw moves to provide a constant rate of elongation of the paper. The movement of the lower jaw can be stopped at the time, and the change in stress observed at the paper remains under constant strain, or the jaw can be backed up to related both the stress and the strain. Stress-strain measurements have the advantages of emphasizing the prerupture characteristics of paper, whereas most conventional tests measure the strength at rupture.

Fig:- Instron tester

Factors that affect stress - strain:-
(1) Page et.al measured the elastic modeulus of softwood fibres and found that when the fibers are free of defects, the plot of modulus against fibril angle give a smooth curve, but defects such as microcompressions, dislocations, and other inhomogeneities in the structure cause appreciable variation in the modulus for fibers with similar fibril angles. (2) Htun and de Ruvo found that the drying stresses of paper measured during restrained drying and the internal stresses in the dried paper measured according to the stress relaxation method are identical. Neither the degree of beating, the level of wet pressing, not thee utilization of different fiber fraction in the sheet changed this relationship.

(3) Where stress-strain curves are plotted for papers conditioned at three different relative humidities. Paper bags are sometimes filled under conditions of high relative humidity because the paper has a greater rte of relaxation when slightly moist. This increased relaxation permits the bags to be filled with less breakage, even though the tensile strength of te paper is lower at the high humidity.

Tensile Energy Absorption
Tensile Energy Absorption:- Tensile energy absorption, commonly termed TEA is a very important measure of the strength of paper. It is the area under the stress-strain curve as the paper is stretched to rupture. Unit for TEA :- It is reported as foot pounds per square foot in the English system; the SI unit is joules per square meter. Measurement for TEA :- Tensile energy absorption is not used as much as it should be because of the difficulty in determining the area under the curve. However, with the development of low cost miniature computers, the tensile tester can be equipped with a small dedicated computer that calculates the TEA from the stress and the strain as the tensile is being determined.

The TEA can be read from the digital redout without calculation except to correct for sample length and sample width. Because TEA combines tensile strength with stretch, it is a measure of the toughness of the paper. Tensile energy absorption can be increased by increasing the tensile or increasing the stretch. Thus a paper containing a microcrepe will have a much higher TEA than will a similar paper without the microcrepe because the microcrepe increases the stretch. Tensile strength is always higher in the machine direction than in the cross direction, but TEA will frequently be higher in the cross direction be cause the stretch is higher in that direction.

Fig:- tensile tester with miniature computer
FiF Fig:- tensile tester with miniature computer

OPTICAL PROPERTIES OF PAPER
UNIT 3 OPTICAL PROPERTIES OF PAPER

WHAT IS PAPER? PAPER IS THE WEB OF FIBERS WHICH IS IREGULARLY INTERWOVEN WITH EACH OTHER. RANDOM NETWORK OF CELLULOSIC FIBER WHICH IS FORM ON PAPER MACHINE

WHAT ARE PAPER PROPERTIES?
PAPER PROPERTIES ARE THE PARAMETER WHICH IS MEASURED IN EVERY PAPER INDUSTRY TO MAKE PAPER OF FINE QUALITY. PAPER PROPERTIES ARE CATEGORIZED INTO CERTAIN PROPERTIES LIKE:- STRENGTH PROPERTIES OPTICAL PROPERTIES(WHICH WE HAVE TO DISCUSS FURTHER) CHEMICAL PROPERTIES ELECTRICAL PROPERTIES

ABOUT OPTICAL PROPERTIESOF WEB
THE WORD OPTICAL RELATED TO LIGHT. WHICH FURTHER EXPAND THE MEANING SHINE,GLOW,LIGHT BRIGHTNESS,ETC OPTICAL PROPERTIES ARE THAT PROPERTIES ARE THAT PROPERTIES OF WEB WHICHSHOWSOR DESCRIBED ABOUT ITS APEAREANCE OF PAPER.

OPTICAL PROPERTIES BRIGHTNESS OPACITY GLOSS

ABOUT BRIGHTNESS OF WEB
THE DEGREE OF WHITNESS OF AN IMPORTANT ATTRIBUTE OF MOST PAPER,WHITE SURFACE ARE THERE WHICH REFLECTLIGHT STRONGLY AND UNIFORMLY THROUGHOUT THE ENTIRE VISIBLE SPECTRUM MATCHING OF PAPER FOR WHITNESS IS STILL DONE MOSTLY BY EYE ALTHOUGH A NO OF INSTRUMENT FOR MEASURING THE COLOUR OF WHITE PAPER ARE AVAILABLE WHICH CAN BE CLASSIFIED INTO SPECTROPHOTOMETER,CLORIMETER,ETC

INSTRUMENTS OF BRIGHTNESS MEASUREMENT

FACTORS AFFECTING BRIGHTNESS
GRADE OF PULP. HOW MUCH OUR PULP IS WASHED? HOW OUR PULP IS BLEACHED? CLEANING OF PULP WHICH TYPE OF OBA (OPTICAL BRIGHTNING AGENT) TYPE OF FILLER USED, HOW OUR DRYING TAKE PLACE AND MANY MORE

IMPORTANCE OF BRIGHTNESS
MAKE WEB CLEAN MAKE WEB ATTRACTIVE APEEARANCE MAJOR REASON FOR HIKING OUT OF WEB EASY FOR GOOD PRINTING G00D FOR CALENDRING AND LOTS OF OTHER

BRIGHTNESS OF DIFFERENT GRADES OF PAPER
GRADE BRIGHTNESS (ISO %) NEWS PRINT OFFICE PAPER BOND COATED PAPER

2. ABOUT OPACITY OF WEB OPACITY IS THE PROPERTY OF WEB WHICH IS DETERMINED BY TOTAL AMOUNT OF TANSMITTED LIGHT IT IS DEFINED AS RESIPROCAL OF AMOUNT OF LIGHT TRANSMISSION i.e. PER FASTLY OPAQUE PAPER IS ONE WHICH IS ABSOLUTELY TO PASSAGE OF ALL LIGHT

HOW TO MEASURE OPACITY? OPACITY IS AN IMP. PROPERTY OF WRITING PRINTING ,PRINTING BOARD,AND IS USUALLY A PART OF SPECIFICATION OF THESE PAPER. IN MEASURING OPACITY A PHOTOELECTRIC CELL IS USED TO REGISTERD THE AMOUNT OF REFLECTED SURFACE OPACITY. OPACITY CAN BE MEASURED BY CONSTRUCT RATIO i.e. BY A RATIO OF DIFFUSES REFLECTANCE WHEN A SINGLE SHEET OF WEB IS BACKED BY A WHITE BODY.

THING’S TO REMEMBER IF GSM WILL MORE OPACITY WILL INCREASE.
IF GSM WILL LESS OPACITY WILL DECREASE. THICKNESS IS INVERSLY PROPORTIONAL TO OPACITY. OPACITY AFFECT ALL THE PROPERTIES OF PAPER LIKE STRENGTH PROPERTIES OPTICAL CHEMICAL FORMATION AFFECT THE OPACITY.

THE PHOTOELECTRIC CELL

OPACITY OF DIFFERENT GRADE OF WEB
GRADE OPACITY % NEWSPRINT (40-49 gram per meter sq.) STATIONARY ( gm per meter sq.) >88 TRACING PAPER ( gm per meter sq.)

3. ABOUT GLOSS OF THE WEB GLOSS IS A PROPERTY OF PAPER WHICH REFERS TO QUANTITATIVE OF GLOSSISENESSDUSTER OR ABILITY OF SURFACE TO SHOW AN IMAGE GLOSS IS A QUALITATIVE PROPERTY WHICH CAN NOT BE EXPRESSED IN FUNDAMENTAL TERMS. GLOSS MAY BE DESCRIBE AS THE CHARACTERSTICS OF PAPER M/C WHICH CAUSE THE PAPER TO REFLECT LIGHT TO GIVEN ANGEL TO REFLECTION IN EXCESS OF DIFFUSE REFLECTION IT THAT ANGLE

MEASURING OF GLOSS GLOSS IS SPECULAR REFLECTION OF LIGHT WHICH IS REFLECTED AT AN EQUAL AND OPPOSITE ANGLE. NORMALLY MEASURED AT 75 degree OR 20 degree GENERALLY GLOSS OF UNPRINTED SHEET/BOARD IS MEASURED AT 75 degree PRINTED SHEET/BOARD AT 20 degree.

GLOSS MEASURING DEVICE
GLOSS METER

IMPORTANCE OF GLOSS IT IS IMPORTANT IN IN CALENDER PAPER MAGZINE PAPER
PACKAGING BOARD GREETING CARDS TRUMP CARDS AND MANY MORE

GLOSS OF DIFFERENT GRADE OF WEB
GRADE OF PAPER GLOSS (%) MAGAZINE PAPER COATED PAPER SUPER CALENDER HOUSE HOLD

OVERVIEW OF PRESRENTATION
WHAT IS PAPER? WHAT ARE PAPER PROPERTIES? WHAT ARE OPTICAL PROPERTIES? ABOUT BRIGHTNESS FACTORS AFFECTING BRIGHTNESS IMPORTANCE OF BRIGHTNESS BRIGHTNESS OF DIFFERENT GRADES OF WEB ABOUT OPACITY HOW OPACITY IS MESURED THING’S TO REMEMBER OPACITY OF DIFF PAPERS ABOUT GLOSS GLOSS MEASUREMENT IMPORTANCE OF GLOSS GLOSS OF DIFF GRADES

CHEMICAL PROPERTIES OF PAPER
UNIT 4

CHEMCAL PROPERTIES The chemical properties of paper are derived primarily from the type of wood used, method and extent of pulping and bleaching and type and amount of non-fibrous constituents edit. The chemical properties of paper are important because they influence the physical electrical and optical properties of paper. CHEMICAL PROPERTIES ARE :- Moisture content Ash content Acidity and pH

MOISTURE CONTENT UNITS INSTRUMENT
The cellulose water relationship is the most important relationship in paper chemistry. The amount water in the individual fibre affects the strength, flexibility, and sheet forming characteristics of fibre. Paper may hold the moisture between the fibres. UNITS %age of moisture content = wt. of Moisture content X 100 AD wt. of sample INSTRUMENT OVEN WEIGHING MACHINE

OVEN WEIGHING MACHINE

TONG CRUCIBLE

Measurement:- The test for moisture content is generally made by drying the paper in an air circulating oven at 1050C for about or untill constant weight is obtained the moisture content is assume to be represented by the loss in weight after drying and is reported as a percentage of original weight. Although the loss in weight when dried at 1050C repeated procedure. The amount removed varies with the amount of moisture in the oven. On a cold day when the relative humidity is very low, as 0.5 % more water will be removed the on a hot day in summer. The vacuum oven is used, an additional 0.5 % or more of water will be removed.

The same effect can be obtained by using air that has past over phosphorous pentachloride and some other good drying agent before entering the oven. The use of vacuum oven or a drying agent will give more reproducible but the moisture content reported will be higher then that obtained in the standard test by using room air. The reproducibility of the standard test can be improved by using air from a constant – Humidity room for the air supply to the oven. When will remain in the paper, but the amount remaining will be relatively constant and the moisture content reported will be about equal to the average value obtained when the air is not controlled.

DETERMINATION OF MOISTURE CONTENT :-
1. Wt. of empty crucible A)= gm 2. Wt. of crucible + A.D Sample B)= gm 3. A.D weight Of Sample C)= B - A = gm 4. Wt. of crucible +O.D sample D)= gm 5. O.D weight of sample E)= D - A = gm 6. Moisture Content F)= C – E = = gm % Moisture Content G)= F/C × 100 = %

%AGE OF MOISTURE CONTENT
S NO. PAPER GRADE WT.OF EMPTY CRUCIBLE (in gm.) WT. OF SAMPLE WT. OF CRUCIBLE +AD SAMPLE WT. OF CRUCIBLE +OD SAMPLE WT. OF OD SAMPLE MOISTURE CONTENT %AGE OF MOIST.CONTENT (in %) 1 WRITING AND PRINTING PAPER 62.182 2.384 64.566 64.376 2.194 0.19 7.969 % 2 PHOTO COPY PAPER 61.273 2.102 63.375 63.260 1.987 0.138 6.494 % 3 DRAWING PAPER 58.890 2.043 60.933 60.827 1.937 0.106 5.188 % 4 NEWS PAPER 61.064 2.151 63.215 63.091 2.027 0.124 5.764 %

Effect of moisture on sheet properties:-
As previously pointed out, moisture affects the rigidity, flexibility, and elasticity of paper, particularly when the moisture content is below above 3%. Changes in moisture content also bring about a substantial change calliper, which is a particularly important factor in case of folding box because of a relationship between stiffness and calliper. The change in calliper reversible unless the board is subjected to a higher relative humidity the that to which it has been previously subjective to higher relative humidity then that to which it has been previously subjected, in which can built-in stress are released.

1. Muffle furnace 2. ASH CONTENT UNITS : INSTRUMENT
Ash is the inorganic substance may be derived from ash in the fibres , ash from pigments used in fillings , ash from sizing agents , ash from minerals matter present in the fresh water, ash from pigments used in coating. UNITS : %AGE OF ASH CONTENT = wt. of Ash content x 100 AD wt. of sample INSTRUMENT 1. Muffle furnace

WEIGHING MACHINE MUFFLE FURNACE

TONG SILICA CRUCIBLE

Measurement:- The amount of ash in the paper is determined by ignition a known weight of paper in a platinum, alunndum, or silica crucible, using a, meeker burner or an electric muffle at about 9250C. Ignition is carried out until the ash is free from specks of carbon, which generally required about 30 to 60 minutes. The results are reported as % of ash to the nearest 0.1% on the basis of the oven dry paper, obtained by correcting for the moisture in the paper.

DETERMINATION OF ASH CONTENT
1. Wt. of empty crucible A) = gm 2. Wt. of crucible + A.D Sample B) = 3. A.D weight Of Sample C) = B - A = = gm 4. Wt. of crucible + Ash content D) = gm 5. wt. of Ash content E) = D - A = – = 6. % Ash Content G) = E/C × 100 = %

%AGE OF ASH CONTENT 1 2 3 4 S NO. WRITING AND PRINTING PAPER
PAPER GRADE WT.OF EMPTY CRUCIBLE (in gm.) WT. OF SAMPLE WT. OF CRUCIBLE +AD SAMPLE (BEFORE BURNING) WT. OF CRUCIBLE + SAMPLE (AFTER BURNING) WT. OF ASH CONTENT %AGE OF ASH CONTENT (in %) 1 WRITING AND PRINTING PAPER 36.77 2.120 38.894 37.071 0.297 14 % 2 PHOTO COPY PAPER 29.57 2.287 31.859 29.985 0.413 18.05 % 3 DRAWING PAPER 37.28 2.126 39.402 37.601 0.325 15.28 % 4 NEWS PAPER 35.61S 2.054 37.668 35.809 0.195 9.49 %

3. Acidity and pH:- The acidity may be determined as the amount of water soluble acidity( or alkalinity), or as the hydrogen ion concentration (pH) of the paper extract. pH is defined as the negative logarithm of hydrogen ion concentration. The pH can be determine by either hot and cold extraction in other cold extraction 1 gm. Of paper is macerated with a stirrring rod in 20 ml. of distilled water 20 to 300C. Then 50 ml more water is added and the sample is left followed in the hot extraction, except that the sample is digested at 95 to 1000C under reflux for 1 hr. instead or merely standing at room temperature. The hot extraction probably gives the more nearly correct pH of the paper.

UNITS :- pH = -log[ H+ ] INSTRUMENT :-
pH & temperature Monitor pH paper

Measurement:- Water soluble acidity is determined by grinding the paper and digesting in boiling distilled water for 1hr under reflux at 98 to 1000C. The digested fiber are then filtered on a Buchner funnel (without filter paper), and then resulting extract is titrated with either 0.01N NaOH or 0.01N HCL, as the case warrant, using phenolphthalein as the indicator. The results are reported as percent of SO3 or percent of Na2O n the basis of the moisture free paper. pH can be determined by hot extraction method in this,, 1gm. Of paper (either cut or ground) is macerated with a stirring rod in 20ml of distilled water at 95to 1000C under reflux for 1hour, instead of merely standing a room temperature. The hot extraction method is more widely used.

Importance of pH:- The pH is very important for bond, ledger and index paper which intended for permanent records. The pH is important in converting papers (e.g., paper for saturating impregnating or coating), since the pH is likely to affect the material used in these converting operations. Bursting strength is reduced approximetly10% in going from a pH 4 to 6 when alum is used for setting rosin size. In ground wood low pH improves the colour and prevents picking on the presses.

4. COLOUR REVERSION A modified fluorescence microscope has been used to sequentially irradiate paper with UV and blue light for known periods of time and to monitor the changes in fluorescence intensity during irradiation. It was confirmed that cellulose shows colour reversion but these effect is far more marked for paper made from high yield pulps. A similar effect is also seen for such papers which have been weathered, bleached with hydrogen peroxide and photo bleached with thiourea – dioxide. The colour reversion process appears to involve both photo-degradation and photo-chromic reactions.

COLOUR PRODUCTION DURING BLEACHING
The first type of yellowing to be discussed is an immediate production of colour during the actual bleaching during process its self. This is a ruther narrow category which really only applies to the use of chlorine type bleaches with ligneous wood pulp paper. The cause is the formation of stable chlorinated fibres which are yellow in colour. The first is acidic hypochlorite. In this case, yellowing is a particular problem when very short bleaching times must be used. The second chlorine dioxide. Most commonly, colour production, which can range from a definite pink to yellow brown, is seen with the gaseous method although it may also be observed with immersion method as well.

Electrical properties of paper and its type
UNIT 5 Electrical properties of paper and its type

Introduction Paper is among the cheapest and best electrical insulating materials known. Although the amount of paper consumed in the electrical field is not large compared with that in other fields, paper is very important insulating material in the radio, telephonic and similar fields.

High dielectric constant (specific inductive capacity )
The important electrical properties foe a good electrical insulating paper are:- High dielectric constant (specific inductive capacity ) High dielectric strength (electrical resistance) Low power factor (dielectric loss) Freedom from conducting particles.

Electrical papers:- Grade Important properties
Coil paper -- high dielectric strength ,tear ,thickness Slot papers -- high dielectric strength , tensile ,tear Saturating paper -- uniformity,thickness,porosity Condenser papers -- thickness, dielectric strength, uniformity Pressboards -- thickness, stability

Condenser paper Condenser tissue is a light weight paper that is used in electrical capacitors and receivers and in telephonic equipment. Condenser tissue is made as thin as possible with good electrical insulating properties. From the standpoint of high dielectric strength and life of paper condenser , it is desirable to use sevral sheets of thin paper , rather than a single sheet of equivalent thickness

Coil paper Coil paper is a thin paper, ranging from 12.7 to 76.2 micro meter thick which is used for wire wrapping transformer , radio wires and magnet wires. The grammage generally ranges from 8-49 g.s.m The paper must not contain corrosive materials that will aatack fine copper wire.

Cable paper Cable paper is a strong paper used in the winding of high and low voltage cables and in transformers, coils and magnets The paper is relatively heavy it generally has a grammage between 81 and 203 g.s.m The paper must be free of pinholes, and it must not contain conducting particles such as Iron.

pressboard Pressboard made on a wet machine in thickness ranging from 127 to 3175 micro meter and is used as insulating material in electrical equipment The stock used is genrally rag or mixture of rag and kraft.

COATING OF PIGMENT PAPER IN PULP AND PAPER INDUSTRY
UNIT 6 COATING OF PIGMENT PAPER IN PULP AND PAPER INDUSTRY

Pigment What are pigments ?
pigment is a material that changes the colour of reflected or transmitted light as the result of wavelength selective adsorption . pigments are generally coloured ,organic or inorganic solid powder , and usually are insoluble Raw material used for pigment coating Pigment Adhesive(used for binding the pigment ) The base paper or raw stock(to which the pigment is bonded)

Blue colour pigment

Pigment coating Pigment coating is an important part of the paper industry. It is a wide field which include the application of many different type of coating to the base paper Pigment coating is a process in which an aqueous mixture of pigment and adhessive is applide to the surface of paper this type coating is used primarly for publication paper used in magazines, although there are many other uses for pigmnet coated paper.

How to use pigment & adhesive
The coating mixture is usually prepared by dispersing the pigment and adhesive seperatly in water & then mixing them together . The the pigment used in common are clay, calcium carbonate ,titanium dioxide etc. The principle adhesive used are starch casein or soya bean protein & synthetic resins usually in emulsion form.

Coating process After the coating mixture has been prepared it must be applied to the paper in the coating process which consist of applying the fluid coating mixture to the base paper smothening, drying & calendring the coating The different type of coating process are:- Off M/C coating On M/c coating Early semi coating process Wet End coating Size press coating Regular M/c coating

Type of coating machine
There are atleast nine method of coating:- Dip Knife Cast roll Brush Air brush Spray Print Extrude strip

Effect of coating on paper properties
Advantages Coated paper has a glossy or matte finish Coated paper are very smooth They have high gloss Coated paper is more resistant to dirt and water Disadvantages Less absorbent to ink then a uncoated paper Less opacity then uncoated paper

Introductory side about specialty paper

Types of specialty paper
Cigarette papers Mottled papers Grease proof papers. Glassine papers. Parchment papers. Security papers. Electrical insulation paper. Fire Retardent paper. Photographic papers. Watermark papers

Cigarette paper Cigarette paper generally contains about 70% cellulosic fiber & 30% precipitated Calcium carbonate. The paper, which is normally made in the substance range of 21 to 26gm per meter sq. should confirm to the following physical properties. Basis Weight ± 2 g/m2 Thickness,(max.) microns Moisture,(max.) % Ash (min.) % Brightness,(min) %

6. Opacity,(min) % Breaking length (min)2 M.D meter C.D meter 8. Stretch, (min) M.D % C.D % 9. Porosity (L / H 40 cm2 / dm H2o)

Besides above properties, the cigarette paper should also confirm to the following requirements. a) It must burn at a specific uniform rate. The impregnation of the fame retardant is an important characteristic. b) It must be free from Wrinkles and should have good opacity. c) It must have a pre-determined porosity. Thu the fiber bend, the quantity & the quality of the filler & the degree of mech.treatment given to the stock.

d). It must meet ash content levels , specified by the customer
d). It must meet ash content levels , specified by the customer. Although alternative to Sunn or Hemp as a raw material for cigarette paper have been tried but the pat practice and even the present experience has indicated that true Hemp ha several advantage over other material. More-over, smoker generally prefer the special flavour of Hemp pulp, which is hygienically acceptable also.

Parchment paper A paper that has been treated by sulphuric acid to gelatinize its surface, subsequently neutralized to render it highly grease resistant & which water resistant, by appearance resembling parchment and often used for packing and protection of products especially foodstuffs containing both moisture and fat.

End –use : Advertisement Brochures, Greeting Cards, Letter heads, Box liners, stationery, etc.
Requirement : Highly grease resistant & water resistant. High wet-strength. Should be odourless, tasteless.

Mottled papers Mottling is a variegated effect produced on the surface of paper by the introduction of a small amount of heavily dyed fibers into stock of another color. Mottled papers are used for social correspondence, for fancy and other effects. Main classes of dyes used in the production of colored papers, specially in beater dyeing, are the acid, direct & basic dyes. The first two classes, acid & direct dyes, are anoinic in nature and are generally sodium salts of color acids.

Basic dyes are salts of color bases and in most cases are either the hydrochlorides or oxalates. They are cationic in nature & are readily soluble in water, especially under acid or neutral conditions. while these basic dyes have strong tinctorial value & brilliancy, they are not always retained by bleached fibers.

Grease proof paper Grease proof paper:- Paper free from mechanical pulp and which without further treatment or added chemicals is given certain grease resisting properties by mechanical means. A protective wrapping paper made from chemical wood pulps, which are highly hydrated in order that the resulting paper will be resistant to oil & grease. This paper is used extensively for wrapping greasy food products. Any paper which has been coated or treated turned as grease proof.

Photographic paper Paper used as the base material for the various photosensitive system employing silver halide crystals as the light sensitive receptors. The paper is manufactured from either cotton or highly purified wood cellulose. It must be free from a foreign substances and chemical impurities which would effect the photosensitive emulsion. They must have sufficient et strength to withstand processing in both acid and alkaline solutions. Most photographic papers are first coated with barium sulphate up to 60gm. Per sq. meter to obtain a high-reflectance surface on which the photosensitive emulsion is coated.

Security paper Paper required for legal documents, currency notes, cheques and other security documents which can be readily identified or authenticated by the user to enable him to ascertain its genuineness. To detect forgeries, the genuine paper should have a feature or characteristics easily detectable, for example, by the bank cashier, but which can not be reproduced without great difficulty. Security paper or authenticable papers contain an Azoic coupling component, which upon treatment with a solution of an Azoic Diazo component produce an insoluble Azo Dye as an identification color, suitable for authenticating the papers.

Glassine paper A super calendered, smooth , dense, transparent or semi-transparent paper manufactured primarily from chemical wood pulps, which have been beaten to secure a high degree of hydration for the stock. This paper is grease resistant to the passage of air and many essential oil vapours used as food flavouring and when waxed , laquered or laminated, is practically impervious to the transmission of moisture vapour.

Glassine paper is used as a protected wrapper for all kind of food stuffs, tobacco products. Chemicals and metal parts as well as many purposes here its transparent features is useful. It is also used as a lining boxes, cartons and as window in window envelopes. It is also called as glazed grease proof paper.

Electrical insulation paper
Electric insulation paper are paper types that are used as electrical insulation in many applications due to pure cellulose having outstanding electrical properties. Cellulose is a good insulator and is also polar, having a dielectric constant significantly greater than one. Electrical paper products are classified by their thickness, with tissue considered paper less than 1.5mils (0.038mm) thickness, and board considered more than 20mils(0.508mm) thickness.

Required for dielectrics in capacitors, for cable insulation applications and for various electrical insulation purposes. Required properties :- 1). High Di-electric strength i.e. low Di-electric loss. 2). High degree of thermal conductivity.

Water-mark paper What is water-mark ?
water mark is a des or pattern given to the paper during production by getting thick or thin layers of fibers hen it is still et. Hence, the name water-mark. It can been seen holding the paper against the light. water-mark changes the thickness of the paper because of varying layers of fibers, depending on the design. History of water-mark:- water-mark have been around almost as long as paper itself. However, it as Italian paper-makers in the 13th century, who really perfected the process. European paper-makers ere the first to use water-marks.

Why water mark is given in the paper ?
water-mark is given in the paper to make counterfeiting more difficult. It is normally provided to avoid duplicacy and forgery of we secured document as in the case of stamp papers used by the court , MICR cheques paper required by the Reserve Bank of India for printing of cheques, Demand drafts and similar other security items. water-mark is also used in currency and in the paper required for permanent record.

PROPERTIES OF CURRENCY & PHOTOGRAPHY PAPER IN PULP AND PAPER INDUSTRY
UNIT 7 PROPERTIES OF CURRENCY & PHOTOGRAPHY PAPER IN PULP AND PAPER INDUSTRY

PAPER Paper:- Paper is a random network of cellulosic fiber. Paper is a thin material produced by pressing together moist fibers, typically cellulose pulp derived from wood, rags or grasses, and drying them into flexible sheets. Material manufactured in thin sheets from the pulp of wood or other fibrous substances, used for writing, drawing, or printing on, or as wrapping material.

THE CHARACTERISTICS OF PAPER
The characteristics of paper can be classified as physical, optical, chemical, or electrical. The physical characteristics include the common strength tests of tensile, burst, tear, and fold as well as such tests as stiffness, hardness, softness, density, weight and thickness etc.

TYPES OF PAPER Various types of paper is: 4. Currency paper 13.
Serial no Paper sample Paper sample 1. Writing and printing paper. 10. Butter wrapping paper 2. News paper 11. Grease proof paper 3. Wrapping paper 12. Bond paper 4. Currency paper 13. Photography paper 5. Blotting paper 14. Chart paper 6. Tissue paper 15. Sand paper 7. Book paper 16. Packing paper 8. Album paper 17. Tea bag paper 9. Carbon paper 18. Filter paper

Currency paper Starch paper blended with the textile fibers (cotton). While making currencies, these papers are instilled with gelatin to give strength to the currencies. Fig: currency paper

Properties of Currency paper
The five primary properties of currency paper(money) are: 1.Folding endurance (double folds). 2.Durability. 3.Transportability. 4.Noncounterfeitability. Other properties are:

Folding endurance (double folds)
Folding endurance of a stripe of paper gives an assess of the resistance presented by the application of outer force in the shape of various and repetitive folds, prior to breaking. Currency paper has the maximum folding endurance.

Durability This properties means that an item retains the same shape form, and substance over an extended period of time; that it dose not easily decompose, deteriorate, degrade, or otherwise change form. However, durability also extends beyond the physical realm to include social and institutional durability.

Transportability This properties of currency paper(money) can be easily moved from one location to another when such movement is needed to complete exchanges. When people head off to the market a purchase or two, then they need to “bring along their money.” That is, the money is not transportable is not transported, so it is not used.

Noncounterfeitability
This properties means that currency paper(money) cannot be easily duplicated. A given item cannot function as a medium of exchange if everyone is able to “print up,” “whip up,” or “make up” a batch of money any time that they want.

Photographic paper Photographic paper is a paper coted with a light-sensitive prints. When photographic prints. when photographic paper is exposed to light it captures a latent images that is then developed to form a visible image, with most printing out papers the image density from exposure can be sufficient to not require further development, aside from fixing and clearing, though latent expose is also usually present. The light-sensitive layer of the paper is called the emulsion.

fig: Photographicpaper

Properties of photographic paper
The stability and useful life of photographic materials depends on their physical and chemical properties, as well a son the conditions under which they are stored and used. The important elements affecting the useful life of photographic materials are as follows: Humidity and temperature of the storage environment; Hazards of fire, water, and light exposure; Fungal growth;

Properties of photographic paper
contact with certain chemicals in solid, liquid or gaseous form; physical damage; proper processing; enclosures and containers in contact with the photographic material.

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