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TT 404 > Test 4 > Flashcards

Test 4 Flashcards

1
Q

how did spun-bonded originate?

A

it was a modification of melt spinning

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2
Q

what is the cost effective way to make a fabric

A

spun-bonded

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3
Q

why is spun-bonding cost effective (3)

A

not a lot of processes, quick, less equipment

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4
Q

when did spun-bonding start

A

1950s

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5
Q

when did patents come out for spunbonding

A

1970s

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6
Q

what is the spun-bond line? (7)

A 
liquefaction 
filtering 
extrusion 
cooling 
drawing 
laying on screen
bonding
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7
Q

why do we filter in spunbonding

A

bc we dont want the spinnerets to get block

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8
Q

what is a gel

A

very small unmelted polymers that can get stuck in spinneret holes

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9
Q

why is cooling an important step in spunbonding

A

they need to be cold before hitting the belt

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10
Q

what polymers are important for spunbonding (2)

A

high molecular weight, medium melt viscosity

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11
Q

why is polypropylene used in spunbond? (2)

A

u can get high yield fabric with low density and can be reused

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12
Q

why is polyester good for spunbonding? (3)

A

good tensile strength, higher modulus, more heat stable

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13
Q

can bicompents and multicomponent be spun-bond?

A

yes

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14
Q

what are the steps of preparation of polymers before spun-bond?

A

crystallization
drying
additive
oxidation

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15
Q

what is the crystallization step of preparation in spun-bonding?

A

need to put in oven and heat up until it crystallizes

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16
Q

what is the drying step of preparation in spun-bonding?

A

if any moisture is left in polymer, when spinning it wont get into thin fine streams and will glob

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17
Q

why do we oxidize preparation in spun-bonding?

A

can get an OH group that something else can be attached to

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18
Q

where are polymer chips stored in spun-bonding and why?

A

in a grail silo so we can blend the polymer chips

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19
Q

why do we have to take fabrics right to bonding when spun-bonding?

A

because the fabrics are so light so we need to bond so they hold together

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20
Q

what is the spin pack

A

the spinneret, filter, metering pump, they are put together as one unit and heated to the right temperature

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21
Q

what happens if the polymers get too cold in spunbonding

A

will have to sandblast the polymer off the spinneret

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22
Q

what is quenching? in spunbonding

A

cooling before the belt, as soon as it comes out of the block it will be hit with chilled air

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23
Q

what does the aspirator or spreader do? in spunbonding

A

separate the filaments before getting to the screen, can spread in MD or CD

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24
Q

why is multilayering a problem in spunbonding

A

because the filaments are so lightweight and it would blow off

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25
Q

why would we do multilayering in spunbonding

A

to hide variations due to randomness

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26
Q

what does the vacuum suction do in spun-bonding?

A

helps hold filaments on the belt since they are so light and need to be bonded straight away

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27
Q

what is the difference between open and closed spun-bonding?

A

everything from spinneret tp belt closed in house, and they have different properties

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28
Q

which system open or closed is less uniform

A

open

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29
Q

what does spun-bonding make?

A

continuous filaments

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30
Q

what is meltblowing

A

fabric directly from polymer with high velocity air

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31
Q

are melt blowing or spun bonding self bonding

A

melt blowing

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32
Q

what is the process of melt-blowing?(9)

A 
polymer
extrude
filter
pump
extra stirring
spinning head 
lay on collecting surface
calendar 
wind on package
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33
Q

what happens in the extrusion process in melt-blowing?

A

we have to blow hot air in dye block so we can keep polymer hot as long as possible

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34
Q

what is the goal of melt blowing

A

to make a fine fiber

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35
Q

what kinds of polymers are made with spunbond

A

special polymers with a low viscosity

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36
Q

what is different about the melt blowing screw?

A

much longer and smaller in diameter

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37
Q

what are the 3 polymers of the dye assembly>

A

polymer feed distribution, die nosepiece, air manifolds

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38
Q

what is the polymer feed distribution?

A

controls how the polymer flows across the block because we dont want dwell times to be too high and control the flow rate

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39
Q

2 types of polymer feed distribution

A

coat hanger and T type

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40
Q

what is the dye nosepiece?

A

wide, hollow, tapered that holds holes that polymer flow to form fibers

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41
Q

what are the capillary type dye nosepiece?

A

drill slots in both sides and match them up

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42
Q

what are the drilled holes dye nosepiece?

A

drilled holes straight through, requires a lot of precision

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43
Q

what are the air manifolds?

A

gaps on both sides of the dye piece and allows us to blow hot air and hit the polymer as soon as it comes out

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44
Q

why is air a major cost in meltblowing

A

being pressurized and heating

45
Q

if we reduce the capillary size what happens to fiber size

A

reduces fiber size

46
Q

what is a drum used for in melt blowijg

A

get electrostatic charge, helps save space

47
Q

why do we calendar bond in melt blowing

A

to help collapse pore size and improve filtration efficiency

48
Q

what are shots in melt bloiwng

A

small particles of polymer that did not melt

49
Q

what is the output rate in melt blowing

A

how much polymer is being pushed through the block

50
Q

small fibers = _ throughout ratw

A

low

51
Q

what needs to be changed before u start the melt blowing process?

A

air gap
air angle
die setback
die hole size

52
Q

are melt blowing highly oriented?

A

no because they are weak

53
Q

what is the difference in air between spun and melt

A

spun need small volume of ambient air

melt needs large volume of very high temp

54
Q

where is spun bond drawing force applied

A

at the attenautor

55
Q

where is melt blowing drawing force applied

A

at the die tip right when the polymer comes out of the dye

56
Q

why do we finish nonwovens?

A

to change appearance, enhance performance, and alter functionality

57
Q

why do we use dry processing a lot in finishing?

A

to reduce cost, enviromental

58
Q

what is shrinking used for?

A

to relieve stresses, remove disortions and promote dimensional stability

59
Q

what are the pros to shrinkage? (3)

A

higher basis weight, higher density or bulk, increases strength

60
Q

what is dry shrinkage primarily used with? (2)

A

high percent of synthetic fibers

low melt fibers

61
Q

what is compacting?

A

sliding fibers closer together

62
Q

what are the pros for compacting? (2)

A

remove paper feel, increase volume of fabric,

63
Q

what fibers are best used for compacting? (4)

A

wet fabric, hydrophilic fiber, heat stability, MD webs are best

64
Q

what is creping?

A

very similar to compacting just at a lower temperature and dry

65
Q

what does creping improve?

A

basis weight up to 50% and elongation

66
Q

what is glazing, calendaring and pressing?

A

calendaring process that uses smooth roll to get stiff highly polished fabric

67
Q

what are the pros to glazing, calendaring and pressing?

A

can reduce pore size, stiffen lightweight web, can change visual effect of fabric

68
Q

what is perforating?

A

hot needles to poke holes in webs, heated needles will cause area around needle to fuse around the hole

69
Q

what is slitting? and what does it improve

A

roller with small blades and improves softness

70
Q

what is splitting?

A

used to take dense needle-punched fabric and split it to make a synthetic leather like fabric

71
Q

what is suede finishing?

A

after splitting we calendar or emboss to give a velour look

72
Q

what is shearing and raising?

A

making loops on the surface and shearing and plucking them to raise them higher, gives feel of carpet

73
Q

what is singeing?

A

burn off protruding fibers from needle-punched fabric to get smooth surface, makes it easier to clean

74
Q

what is sewing and quilting?

A

joining 2 webs together

75
Q

what can we weld?

A

two thermoplastic materials today

76
Q

what is washing?

A

normal washing just with full width washers and dryers

77
Q

what is dyeing?

A

combining chemical bonding and dyeing

78
Q

what are the challenges of dyeing? (2)

A

need to make sure binders are compact-able with dyes, and difficult to dye when web contains blends of different fibers

79
Q

what can stiffening accomplish?

A

can add 300% of web weight, but u need to apply several layers

80
Q

what is flocking?

A

lay down pattern and adhesive and have short fibers to stand up where the pattern is

81
Q

what is a composite

A

combination of two or more materials with an interface

82
Q

what do have an interface in composites?

A

to maintain the distance properties of each material , we want them to bond while still maintaining the properties

83
Q

how are composites economical?

A

eliminates steps and can replace products

84
Q

when making a composite what fiber properties do we need to consider (6)

A 
fiber type
fiber length
fiber diameter
porosity 
airflow
cross-sectional shape
85
Q

what is a fuzzy interface?

A

when two fibers mix together, not easy to pull apart

86
Q

what is a clear interface?

A

can peel apart, veeners

87
Q

what is a veener?

A

low melt in between and will cause it to stick and can peel apart

88
Q

what was the process of the original medical blue?

A

spun laced, carded web and tissue paper web that we hydroentangle then coat it with polyurethane to give the barrier properties

89
Q

what was wrong with the original medical blue

A

not breathable, had absoportion and barrier properties

90
Q

what is an extrusion coating?

A

marrying a nonwoven w a film on

91
Q

how do we add active ingredients to a web

A

either bonded within the fiber itself or put in the web and hoping it stays

92
Q

how do we make a 3D needle-punched composite?

A

lay down needle-punched web and put down a layer of carbon and selectively needle-punch to connect the 2 webs, making pockets

93
Q

how do we activate carbon?

A

lay down low density web, intermingle particles in air web system and then lay down another layer

94
Q

how do we much sure activated carbon last longe?

A

make sure particle sizes are larger than your fiber size

95
Q

what do we use in automotive composites?

A

hemp of kenalp because it is very stiff

96
Q

what is a depth filter?

A

have different layers responsible for picking up different size particles, each layer can have different chemistry.

97
Q

what is caking?

A

when it gets clogged because the small particle layers are on top

98
Q

what is stitch bonded

A

low melt yarn that melts and is abrasive part, stitch bond also serves to hold it together

99
Q

spunbonded open system characteristics (5)

A 
high filament speed
finer fibers
flexible
most polymers
shorter height
100
Q

spunbonded closed system characteristics (5)

A 
better bonding 
good uniformity 
well defined process
mostly PP 
not affected by room air
101
Q

typical process of melt blowing (5)

A 
extruder
metering pump
die assembly 
web formation
winding
102
Q

processing material variables in melt blowing (5)

A 
polymer type
molecular weight
molecular weight distribution
melt viscosity
polymer additives
103
Q

processing machine variables in melt blowing (6)

A 
polymer/die temperature
air temp
die to collector distance 
collector speed
polymer throughput 
air throughput
104
Q

what does a high DCD cause (5)

A 
bulkier and softer web
better fiber cooling 
less tendency to disturb fiber lay down 
less web uniformity 
used for heavy basis weight fabric
105
Q

what does a low DCD cause (4)

A

more compact/stiffer web
balance if process air and suction capability
more uniformed web
used for light basis weight fabric

106
Q

how to reduce shots (5)

A 
reudce output ratw
reduce air temp/ increase air flow
replace die tip if necessary
reduce melt temp
check for resign quality
107
Q

product characterisitcs of a melt blown (7)

A 
random fiber orientation 
low to moderate web strength
high cover factor
fiber diameter ranges from .5 to 30 microns 
basis weight ranges from 8 to 350 g/m2
fibers have a smooth surface texture
microfibers provide high surface area
108
Q

lamination methods of composites

A 
thermal bonding
ultrasonic bonidng 
adhesive bonding 
extrusion coating 
needlepunching 
hydroentanglingn

TT 404 (6 decks)

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