專外-以前課程第5次

CH

A

P

T

ER

7Manufactured

Cellulosic

Fibers2Words

list全部New

words

3，6，7，12，13，21，22，26，34-36，46，48，50,57，58，62。Today,three

cellulosic

fibers,with

quitedifferent

properties,are

defined

by

the

TFPIA.Theyareacetate(醋酯纖維),triacetate（三醋酯纖維）,and

rayon34acetate—a

manufactured

fiber

in

which

theforming

substance

is

cellulose

acetate.Wherenot

less

than

92%of

the

hydroxylgroups

（羥基）areacetylated（乙?；模?the

termtriacetate

may

be

used

as

a

genericdescription

of

the

fiber.5Rayon-a

manufactured

fiber

composed

ofregenerated

cellulose,as

well

asmanufactured

fibers

composed

of

regeneratedcellulose

in

which

substitutents（替代物）have

replaced

not

more

than

15%of

thehydrogens氫of

the

hydroxyl

groups羥基6Commercial

Development酸鹽溶于RAYONViscose

Rayon:它是由纖維素纖維氫氧化納而制得的。Cuprammonium

Rayon銅氨纖維:它是溶于含氨的氧化銅溶液中的纖維素經(jīng)沉淀生產(chǎn)出的絮縈長絲，即為銅氯絮縈纖維Solvent-Spun

RayonACETATETriacetate7Historically,two

methods

of

rayon

the

viscoseand

cuprommonium

have

beencommercialized.(商品化)8Cuprammonium

RayonThe

cuprammonium

process

was

introduced

in

Germany

in

1891,and

commercial

fiber

wasproduced

starting

in

1901,The

process

wasmodified

in

1926

by

J,P,Bemberg

AG

ofGermany.The

fiber

was

produced

in

theUnited

Stales

by

American

BembergCorporation,which

was

bought

by

BeaunitCorporation.Production

in

the

United

Statesceased

（停止）

in

1975;the

reasons

cited

,引證for

discontinuingproduction

were

the

problems

of

treatingprocess

water

to

meet

effluent

water

qualitystandards.Effluent

：（a）發(fā)出的，流出的（n）污水，廢水9Solvent-Spun

RayonA

third

method

of

rayon

production

is

currentlyapproaching

commercial

success.

TheCourtaulds

Genesis Project

developed

asolvent-spun

cellulose,

which

was

introducedas

Tencel

1989.

Courtaulds

North

America

willproduce

the

fiber

in

the

United

States

at

theirMobile,

Alabama阿拉巴馬州(

的一個州),plant.

Lenzig

AG

of

Austria

has

alsocommercialized

a

solvent-spun

rayon.10Lyocell纖維是英國考陶爾茲公司和奧地利蘭精公司分別于20世紀(jì)90年

發(fā)的新型纖維素纖維。國外Lyocell纖維的應(yīng)用已非常普遍，技術(shù)較成

熟，而國內(nèi)尚屬開發(fā)應(yīng)用階段。為了盡快利用好世界領(lǐng)先的新纖維材料，積累經(jīng)驗，提高產(chǎn)品的檔次和質(zhì)量，生產(chǎn)一些高附加值產(chǎn)品，參與國際紡織品市場的激烈競

爭，不斷滿足市場和客戶的需求，筆者認(rèn)為：用好Lyocell纖維、紗。在掌握其特性的同時還應(yīng)重視以下幾方面的問題，并加以解決。1

概述Lyocell是纖維的學(xué)名，商品名叫Tencel,我國俗稱天絲。它是采用全新溶劑在制造過中可回收，產(chǎn)品使用后的廢品可生化降解，所以稱之為“21世

紀(jì)的綠色纖維”。Lyocell纖維的橫截面呈圓形，聚合度、結(jié)晶度高，初始模量、濕模量高；具有高強、低伸、干濕強度相仿、剛性強、表面光滑而干燥、收

縮率低及呈原纖化特征；吸濕性、舒適性、光澤性、染色性及生物降解性、尺寸穩(wěn)定性都相當(dāng)優(yōu)良。Lyocell纖維可以純紡，也可與棉、麻、毛、絲或 纖

維混紡，制成品種繁多的各種特色的機織物和針織物，提高和改善織物的性能，適應(yīng)各種時尚潮流。11Fiber

ProductionPULP

FORMATIONWood

pulp

andcotton

linters(棉仔絨，棉短絨)are

the

two

majorsources

of

purified

cellulose

純凈纖維素for

manufacturing

acetateand

rayon.

Wood

pulp

is

produced

from

timber（木材。木料）After

the

Bark

(樹皮)is

removed,the

wood

ischipped

into

verysmall

pieces.

The

wood

chips

are

treated

with

calciumbisulphite（亞硫酸鈣）

and

thseveral

hours.

The

woodamed

under

pressure

forposes,

and

a

purified

formorCellulose

is

produced.

This

blenched

with

h

lorite（次氯酸鹽）

and

pressed

into

a

sheer

of

pulp,

which

esthestarting

productfor

fiber

manufacturing.

Sheet

ssomewhat

softer

and

lessdense

than

products

similar

informcalled

paperboard卡紙

and

blotting

paper吸墨水紙.12Viscose

RayonFigure

7.2

is

the

basic

flow

diagram（流程圖）

forviscose

rayon

production,The

principal

raw-material

for

viscose

rayon

is

a

refined精制、提純

grade

of

wood

pulp.Sheets

of

cellulose

pulp,about

0.6

meter(2

ft)

square,

are

steeped浸漬ina

17.5

percent

solution

of

sodium

hydroxideuntil

the

cellulose

is

converted

to

alkalicellulose.Flow

chart13壓榨老化黃化15The

alkalized

sheets

are

then

shredd扯碎

to

crumbs（碎屑）

and

aged

for

varying

periodsof

time

up

tothree

days.

The

aging

（老化，熟化）process

involves

achemical

reaction between

alkali

and

oxygen

in

theair,

which

reduces

the

length

of

the

cellulose

polymerchain

from

high

degree

of

polymerization

to

a

lowerdp,

suitable

for

the

desired

type

of

rayon

to

be

made.The

reaction

time

in

the

aging

process

depends

onthe

starting

dpof

the

pulp,

the

chemical

reactivityof

the specific

pulp

used,

the

presence

of

a

catalyst,and

temperature.After

aging老化,

the

alkali

cellulose

crumbs（碎屑）are

reacted

with

carbon

disulfide(二硫化碳).

Up

tothis

point the

soda

cellulose堿纖維素

hasbeenwhite,

but

the

carbon

disulfide

changes

it

to

abright

orange

product

called

sodium

cellulosexanthate酸纖維素鈉.1617Tile瓦片

xanthate黃酸鹽

crumb碎片

isdissolvedin

dilutesodium

hydroxide

(

5

to

8

percent

NaOH)

andforms

aviscous(粘液hence

the

nameviscose),honey-colored

liquid

(Figure

7.3).

This

solution

isaged熟成

untilit

reaches

the

correct

degreeofcoagulation

（凝結(jié)）

for

spinnability

atspecifiedconditions.

Therelationship

betweendegreeofcoagulation

and

spin

bath

conditions

influencesthe

kind

of

productobtained

andis

akey

elementin

the

“art”

ofmanufacturing

rayon

fibers.

Keyfactors

in

viscose

production

includeconcentration（濃度）,

degreeofpolymerization

ofthe

cellulose,

the

presence

ofadditives,temperature,

andthe

amount

ofreverse

reaction可逆反 of

xanthate黃化反應(yīng)

that

hasoccurred

prior

tospinning.The

viscose

is

filtered

and

deaerated(脫氧，脫泡).delivered

to

the

spinning

pumps(計量泵),andforced,

by

individual

pumps

for

eachspinnerette噴絲頭,into

an

acid

bath.The

bathand

spinning

conditions

for

viscose

rayon

arecontrolled

carefully

to

maintain

fiber

quality.18The

spin

bath

for

viscose

rayon

contains

sulfuricacid(H2SO4硫酸),sodium

sulfate(Na2SO4硫酸鈉)water,and

certain

additives

such

as

glucose(葡萄糖)andzinc

sulfate（硫酸鋅）.Thecomposition（混合，構(gòu)成）

and

temperature

of

the

spin

bath

influence

the

rates

of

coagulation

of

cellulose

xanthate

andits

subsequent

regeneration

to

cellulose.Thesefactors

alsoinfluence

thecross

sectionandwhether

or

notalatent（潛在的）

crimp

can

beimparted（給予）

to

the

final

fiber.Sodium

sulfate

isthe

primary

coagulation

medium.Theacidneutralizes

excess

caustic(苛性堿)in

the

viscoseand

coagulates

the

cellulose

xanthatefilaments.Zinc

sulfate

moderates

the

rate

of

regenerationby

slowing

theprocess.19The

cellulose

xanthate

filaments

are

withdrawncontinuously

from

the

acid

bath

and

are

furthertreated

with

warm

dilute

acid

to

forceregeneration

of

the

cellulose

xanthate

back

topure

cellulose,with

the

release

of

carbondisulfide(二硫化碳),The

filaments

are

stretched,ordrawn,during

the

regeneration

step.The

degreeof

drawing

controls

fiber

tenacity

and

modulus。High

draw

ratios

are

used

to

produce

high-tenacity

and

high-wet-modulusviscose20These

two

steps,

coagulation

andregeneration,

make

up

the

wet

spinningprocess

for

rayon.

After

regeneration

thefilaments

are

thoroughly

washed

to

removeany

impurities

that

might

be

stuck

to

them.They

are

either

combined

directly

into

filamentyarns

or

cut

into

short

lengths

for

spinningstaple

yarns.21Other

attempts

to

producehigh-tenacity

rayon

haveused

solvent-based

systems,which

not

producecellulose

xanthale

and

therefore

do

not

make

trueviscose

rayons.Attempts

have

been

made

to

spinhigh-tenacity

cellulose

from

N-methylmorpholine

N-oxide(NMMO)

and

a

series

of

calcium,zinc,magnesium,and

ammonium

salts.High-speedspinning

improved

fiber

tenacity,but

the

fiber

hadmicrofibrils

(原纖)aligned

parallel

to

the

fiber

axis,whichcaused

pilling

problems.Tencel.a

high-strengthrayon

produced

by

a

solvent

spinning

process,will

be

discussed

later

inthis

chapter.2223High-Wet-Modulus

Rayon

Thehigh-wet-modulusfibers

have

a

higher

degree

of

polymerizationthansome

other

viscose

products.Many

use

higher

ratiosof

caustic

to

cellulose

and

of

carbon

disulfide

tocellulose

in

fiberproduction.Additional

regenerationrate（再生速率）

modifiers

may

be

added

to

thespinbath,the

bath

temperature

may

be

reduced,andchanges

inthe

chemical

composition

of

the

bathmaybe

made.Lowersalt,higher

zinc,and

lower

acidconcentrations

are

used.Immersion

time

may

belengthened

and

a

higher

draw

ratio

used.24Wash

and

wear:免燙，洗可穿ACETATEThe

pretreated

cellulose

is

transferred

tokneading(混合，攪拌)

machines

calledacetylators（乙酰化器）,

where

aceticanhydride醋酸酐

is

added.2526STRESS-STRAIN

RELATIONSA

comparison

of

the

tenacity

and

elongation

ofseveral

cellulosic

Fibers

may

be

made

bystudying

the

stress-strain

curves

of

some

ofthe

major

fibers(Figure

7.8).Becauseacetate

fibers

have

fewer

associative

forces結(jié)合力between

the

molecular

chains

than

rayonfibers,acetate

fibers

generally

have

lowertenacities.2728The

manufactured

cellulose

fibers

tend

to

losestrength

when

wet.

The

high-wet-modulusfibers

do

not

lose

as

much

strength

as

regularrayons.

as

shown

in

Table

7.229A

wide

rangeof

stress-strain

characteristics

isavailable

in

manufactured

cellulosic

fibers.

Bylooking

at

the

stress-strain

curves

of

the

fibers,

therelative

toughness

and

resilience(彈性恢復(fù)力)

of

aseriesof

fibers

can

be

determined.

In

general,cellulosicfibers

have

poor

resiliency

and

must

be

treated

withspecial

finishes

to

improve

their

recovery

fromwrinkling,crushing壓碎,

碾碎,

壓服,

壓垮, ,

(使)變形,

andcreasing折痕.

Triacetate

fibers

havethe

best

resiliencyof

the

cellulosic

fibers.30MOISTURE

REGAINIn

general,

relatively

amorphous

fibers

absorb

moremoisture

than

more

crystalline

fibers.

The

presence

ofhydroxyl

groups羥（基）氫氧基increases

moistureabsorbency.Rayon

absorbs

more

moisture

than

acetate,and

diacetate[有化]雙乙酸鹽[酯]absorbsmoremoisture

thantriacetate.At

standard

conditions

of

70°F

and

65

percentrelative

humidity,the

moisture

regain

of

regular

viscoserayon

is

13

percent;

of

Tencel,11.5

percent;

of

acetate.6.5percent;

and

of

triacetate,

about

5.2

percent.Thedifferences

in

the

fibers'

moisture

absorbency

affects

thedyeing

and

finishing

characteristics

of

the

fibers

as

wellas

theircomfort

properties

and

care

requirements.31SunlightMost

rayon

fibers

are

similar

to

cotton

in

theirto

sunlight,

but

prolonged

exposureto

ultraviolet

radiation

tenders

rayon.

Acetatealso

is

tendered

by

prolonged

exposure

tosunlight.

Acetate

drapery裝飾織物，懸掛織物

linings

內(nèi)層襯套eventually

develop

splits

，裂口、裂痕

intheareas

exposed

to

sunlight,

Delustered

fibersare

more

sensitive

to

actinic

degradation（光化降解）

than

are

bright

fibers.3233BiologicalThe

sizing(漿紗)or

starch（上漿）

o