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PSE FINAL > Test 3 > Flashcards

Test 3 Flashcards

Refining, Paper machine, etc

1
Q

Retention Aid

A

used as a glue for fines and filler particles to fibers so they don’t pass through the paper machine

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2
Q

Types of retention aids

A

cationic starch, polyacrylamides

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3
Q

Sizing Agents

A

makes fibers/sheet water-repellent for improved printing and better stability in humidity

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4
Q

What kinds of sizing agents are needed for different grades?

A

Linerboard- liquid resistance
Printing and writing- controlled penetration

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4
Q

What are the goals of fillers?

A

improve sheet opacity by providing light-scattering surfaces
improve sheet smoothness and printability

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4
Q

What are fillers?

A

inorganic material added to improve certain characteristics

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5
Q

What are strength agents?

A

polymers that improve the dry or wet strength of sheets. polymers bridge across bonding areas between fibers

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6
Q

Dry strength agent examples

A

starches, gums, synthetics

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7
Q

Wet strength agent examples

A

PAE, GPAM, resins

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8
Q

Alum

A

Al2(SO4)3, improves drainage, additive effectiveness

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9
Q

Chest types

A

Dump chest, mix/blend chest, machine chest

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10
Q

Dump chest purpose

A

recives the raw fiber, may be a hydrapulper

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11
Q

Blend chest

A

receives stock and furnish components, often feeds the refiners

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12
Q

Machine chest

A

receives refined stock, feeds the stuff box

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13
Q

Headbox consistency

A

.5-1%

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14
Q

What is refining?

A

physical treatment performed on pulp fibers to improve their papermaking characteristics

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15
Q

What does refining do to the individual layers?

A

Removes P and S1 layers, collapses S2 layers

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16
Q

What is the Canadian Freeness Test?

A

Most common North American Test, measures the dilution of pulp

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17
Q

How does refining improve grades?

A

Better tensile/burst strengths, formation, smoothness, and printability

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18
Q

How does refining hurt grades?

A

Worse tear strength, bulk, drainage rate, air porosity, yield, and opacity

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19
Q

Stuff box function

A

overflow box, providing constant pulsation above basis weight valve

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20
Q

Basis weight valve funtion

A

scanner, meters thick stock to set sheet basis weight

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21
Q

Fan pump function

A

huge pump which mixes thin stock and white water to produce thick stock

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22
Q

Headbox cleaners function

A

used fro grades that require low level of contaminants, centrifugal force used to remove dense contaminants

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23
Q

Headbox pressure screen function

A

induces pulsations in the stock to bust up fiber flocs and ensure good formation

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24
Q

Three sections of the wet end

A

Gravity, vacuum and press

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25
Q

Goals of wet end

A

distribute the paper stock uniformly across the machine, remove most of the water, press the dewatered sheet

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26
Q

Fourdrinier strengths and weaknesses

A

strengths: simple, good retention
weakness: limited rate, two sidedness can occur

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27
Q

Top wire former strengths and weaknesses

A

strengths: permits water removal on both sides, can be easily added to existing fourdrinier
weaknesses: lower retention of fines and filles, two wires to maintain

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28
Q

Gap former types

A

S, C or crescent former

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29
Q

Gap former strengths and weaknesses

A

strengths: good for fragile sheets, high speed, no two sideness
weaknesses: complex, two wires to maintain, formation set in the headbox, poor retention

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30
Q

6 Ds of papermaking

A

Dose: thick stock to achieve basis weight
Dilute: use white water, used for formation
Disperse: put high shear to break up flocs
Distribute: dilute uniformly
Dewater: remove free liquid
Dry: use heat to evaporate water

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31
Q

Gravity section

A

set formation of sheet, 85% of total water, sometimes involves microturbulence

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32
Q

Headbox function

A

provides pressure necessary to deliver correct amount of thin stock

33
Q

Slice funtion

A

opening at the lip of the headbox, can be adjusted to change basis weight

34
Q

Basis weight CD profile

A

dilution headbox uses a series of water injector tubes to dilute heavy spots

35
Q

Forming fabric

A

moving wire that supports the stock/sheet and allows water drainage

36
Q

Breast roll

A

support roll for fabric, usually has a shower under the headbox to keep clean, may have a shake mechanism

37
Q

What is formation?

A

a general term that describes how well fibers are distributed in finished paper sheets

38
Q

Forming board

A

supports wire where the stock first comes in contact with the wire

39
Q

table rolls

A

rotating devices which removes water and supports the wire
causes pressure pulse on the front end and vacuum spike on back end

40
Q

Hydrofoils

A

static drainage devices, similar to table rolls, less intense pulse

41
Q

Foils

A

front end of each foil, strips off the water from the previous foil

42
Q

Vacuum Section

A

15% removal, goal is to do so without harming gross sheet structure

43
Q

Vacuum foils

A

foils attached to a vacuum header to extend the vacuum zone after the foil blade

44
Q

Vacuum boxes

A

perforated or slotted boxes under the wire, water removed from passing sheet through holes

45
Q

The Dry Line

A

a line separating the glossy draining sheet from the duller dewatered sheet

46
Q

The Dandy Roll

A

wire, mesh covered roll which rides lightly on top of sheet, near the first flat box, levels wet paper surface, improving formation and smoothness

47
Q

Steam Boxes

A

usually placed over the top of flatboxes, allowing more water to be drained

48
Q

Trim Squirt

A

high pressure water nozzles, used to trim off the ragged outer edge, trimmed edges fall into couch pit and are recycled

49
Q

The Couch Roll

A

place where paper is released from the forming wire and onto the first press felt, has some suction

50
Q

Press section

A

removes water without crushing sheet

51
Q

Press felts

A

nylon based fabric used to form fluffy surface, cover the rolls that are on the press nip

52
Q

Dry End

A

uses heat to remove .5% of water, dried while the sheet is stretched

53
Q

Steam Economy

A

Lbs steam used/ lbs water evaporated

54
Q

Surface Sizing

A

On the size press, improves strength and smoothness of

55
Q

Calendering

A

a mechanical treatment carried out on the sheet after drying, flattens out the sheets ridges, reduces thickness

56
Q

Dry End Scanning

A

pass different rays through the sheet to measure properties, such as caliper and strength

57
Q

Reels

A

where the paper is stored, at the end of the machine

58
Q

Slitter-Rewinder

A

cutes reel into desired roll sizes, is designed to run fast

59
Q

Multi-Headbox Fourdinier

A

first headbox is followed by gravity and vacuum section, then a second headbox is dewatered

60
Q

Multiple Fourdrinier

A

multiple headboxes and lines formed together before press section

61
Q

Multi-layer headboxes

A

multiple streams feed into a single headbox, usually good for tissue

62
Q

Why coat paper?

A

coating fills in the remaining micro pores on the surface of the sheet

63
Q

Pigments

A

Clay, calcium carbonate, TiO2, Al2O3. All used for color purposes

64
Q

Binders

A

latex, starch, proteins. add mechanical strength to the dry coating

65
Q

Typical Coating Operations

A

dry paper
use size press
dry again
use calendrer stack
apply coating
dry using steam
calendaring again

66
Q

How to get premium softness (tissue)

A

80% bleached eucalyptus kraft, 20% bleached northern softwood kraft.
new way: combine hard and soft wood

67
Q

Twin wire gap former

A

stock is injected into a gap formed between two forming wires.
advantages: compact, fast, both sides identical

68
Q

S wrap former

A

stock injected horizontally or inclined, then goes through an s motion in-between wires

69
Q

C wrap

A

stock jet directly vertically between forming wires and moves up and around
advantages: good for two ply sheets, can go faster, less stress on the sheet

70
Q

Cresent Former

A

horizontal headbox injects between a felt and wire
advantages: no transfer wire, low cost, high efficiency, good quality

71
Q

Yankee Dryer

A

uses creping, sheet is dried while supported and restrained, scaped off at the end then creping is induced

72
Q

Through Air Drying

A

forced hot air through wet sheet, can be done on a Yankee dryer

73
Q

Drying terms

A

LDC - lightweight dry creping
TAD - through air drying
CTAD - creped through air drying
UCTAD - uncreped through air drying

74
Q

Market Pulp

A

one fiber type, no additives, not refined, formation not important, dried unrestrained, sold in bales

75
Q

Critical Attributes of Market Pulp

A

brightness, uniform fiber length, cleanliness, high viscosity

76
Q

Fluff Pulp

A

southern softwoods make the best fluff, good at transporting and holding liquid

77
Q

Super Absorbent Polymers

A

most common: polyacrylic acid, used for hygiene, spill clean up and bandages

78
Q

Gel blocking

A

a group of SAP particles, also used in many absorbent heavy products

79
Q

Hammermill

A

uses rotating hammers to beat apart fluff pulp, creates a fiberized pulp

80
Q

Fluff pulp characteristics

A

intermediate product, heavy, weak, only softwood, high cleanliness, no surface, lightly calendared, uniform caliper

81
Q

Big 7 for Fluff Pulp

A
  1. fiberization energy
  2. low dirts
  3. high brightness
  4. high viscosity
  5. uniform caliper
  6. water absorption
  7. reel moisture
82
Q

Cellulose Acetate

A

acts like a plastic, found in phones, cigarettes

PSE FINAL (2 decks)

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