NBS5 Preservation of Documents by Lamination

7/21/2019 NBS5 Preservation of Documents by Lamination

1/28

N S

M

ONO

GR

PH

P

r e

s e r

v a

t io n

o

f o

c u

m e

n t s

b

y

L a

m i

n a

t i o n

U

S D

E P A

R T M

E N

T

O F

O M M E R E

N A T

IO N

A L B U

R E A

U O F

S T A N

D A R

D S


2/28

THE NATIONAL

BUREAU

OF

STANDARDS

un

ctions and Activities

The f

unctions

of the

National

B

ureau

of

Standards are

set

forth

in the Act of

Congress,

March

3, 1901, a

s

amended by Congress

in Public Law 619, 195 0. These include the

development

a

nd

maintenance of the national standards of measurement

and the provisionof m e

ans

and m

ethods

for

making measuremen

ts consistent with these standar

ds; the determination

of

physical

co nstants

and

properties

of materia

ls; the development

of

methods and instru

ments

for

testing

materials,

devices,

ana

structures; advisor

y

services to government

agencies on scientific and technical problems;

in

vention

and

development

of

devices

to

serve special needs

of

the

G ov ernment; and

the development

of standard practices, codes,

and specifications. The work includes basic and a

pplied

research,

development, engineering, instr

umentation, testing, evaluation, ca libration services,

and

various

co n

sultation

and inform

ation services. Research projects ar

e also

performe

d for

oth

er govern

ment

agencies when the work relates

to and

supp

lem ents the basic program

of

the

Bu

reau or when

the

B

ureau's unique com

petence

is required.

The

scope

of activit

ie s

is sugge

sted

by

the listing of

divisions

and sections on the inside

of

the back cover.

Publications

The results of

the Bureau's work take

the

form of

either actual equipment and devices

or

pub*

listed

papers. These papers

appear

either

in the Bureau's own

ser

ies

of

publications or in

the journals

of professional and scientific societie

s. The Bureau itself

p

ublishes three periodicals

available

from

the Government Printing

Office: The Journal

of

Research, published in four

separate sections, presents

complete

scientific and

technical

papers;

the

Technical

New s

Bulletin

presents summary

and

pre

lim

inary

reports on

work in pr ogress; and

Basic Radio

Propagation

Prediction

s

provides

data

for

determining

the best frequencies

to

use for

radio

communications

throughout the world.

T

hereare

also

five

series of nonpenodical publications:

Monographs,

App

lied Mathematics Se

ries,

Handbo

oks,

Miscellaneous

Publications,

and Te

chnical Notes.

Information on

the Bureau's

publicatio

ns can

be

found

in

NBS

Circular

460, Pub

lications

of

the Nat ional Bureau of Standards ( 1.25

)

an d

its Supp

lement

( 1.50),

available

from

the

Superin

tende

nt of Documents, Government

Printing Office, Washington 25, DC


3/28

UNITED STATES DEP

ARTMENT OF COMMER

CE Frederick

H Mueller ecretary

NAT

IONAL BUREAU OF

STANDARDS A V .

Astin i re tor

Pre

servation

of

D

ocuments

by

Lami

nation

W

illiam

K.

Wilso

n a

nd B .

W.

Forshee

National Bureau

of Stand

ards Monograph

5

Issued October

30 1959

For

sale by the Superintendent

of Documents U.S. Go v

ernment Pr i

nting

Office W

ashington

25

D .C.

Pric

e 20 cents


4/28


5/28

Con

tents

Page

1 Introduction --______--__---

-_______-_____-__ .___-----_--___- ___-____

2 Properties

of

an ideal

laminatin

g

film.-_____-___-___

-_______..--______.._ 1

3

Properties

of cellulose acetate lami

nating

film_

____.-^__-____---._-_____._-. 2

3 1

Stability

o

f cellulose acetate films__-_______________________

_________ 2

3 2 Plasticizer

loss

of

cellulose acetate films.-

___

_______________________- 4

a

Gen

eral -__________________..______________-____-__

__ _____ 4

b.

Materials

and

methods

of

test__-______.______-_-..________--__

5

c Results and discussion..._____

__-_______.. .______-__-.._-_-__-_ 5

3 3

Physic

al

prope

rties of cellulose acetate films.____-_^___

-____-.-_-______ 7

a. GeneraL__--_-______

_--___-_--___--____--.._-.._-___-_-____ -_ 7

b

Materials

and methods of test. __________ .._-

___-_______-_-._-_- 8

c

Results

and discussion____-_____

--.- -_.._--____.._..______-- 9

4 Degradation of

film

a

nd

paper during

lamination^___-______._-____-__

_____.

11

5 Tissue

reinforcement___-___

________.._-_______-_^____-_~ .___-__________ 12

6

Deacidification_-____

_____-_______._________________^_-______-_ ____

__ 14

7 Special

laminating methods_____-___________________-__

_________________ 15

8 Preliminary

study

of

films other thancellulose acetate__-_.__.__.__-____

16

9 Specifications for archival

laminating film formulated

from

cellulose acetate__

17

9 1 eneral_

__________________________________

____ 17

9 2 Test

method

s_____ _

_______________________ 17

9 3

Improvements

in

specifications_^______^________-__-_________-___

18

9 4

Problems

in

procurement______-____.-______ ._-_-__

_-__-_-_- 19

10 References..___-____-_._.______._._._

._._._-.__-____-..-.-________

19


6/28


7/28

Preservation of ocuments

by Laminatio

n

William

K

W ilson

and

B W

Forshee

The chemical stability

and

physical

p

roperties

of

cellulose

ace

tatefilm

used

to

preserve

and restore old or

damaged documents by lamination were investigated. Pretreatment

of

documents with alkaline media before lamination is desirable if the

paper

contains

an

appreciable amount of acid. The lamination process

does

not

degrade cellulose

acetate

film

to

a measurable extent. Acid-free papers are not

degraded

during

lamination, but papers

containing acid are degraded in proportion to th

e amount

of

acid present. Tissue added to

the

lam

inate

increases

the tensile st

rength

and

internal tear resistance, but decreases edge tear

resistance as compared tothat of film

alone extending beyond the pa

per.

The

loss of

plasticizer with time from

a

cellulose acetate laminating film

does

not impair

the properties o

f the

laminate.

Composition and performance specifications for a

cellulose

acet

ate

laminating film suitable

for

archiv

al use are

presented.

The propertie

s of p

oly

ethylene

and

polyethylene

terephthalate

films of int

erest in

c

onnection with their possible

u

se for the

pr

otection of documents

are discussed.

1

Introduction

The lamination of documents with cellulose

acetate film

as

a means of preserva

tion and

resto

ration

has

been

pract

iced

for more

than 20

year

s

[I].

The National Bureau of

Standards

was asked

by the National Archives Army

Map

Service, Library of Congress, an

d

Virgini

a

State

Library

to

investiga

te

several aspects of

the

preservation

of

documents b

y

lam

ination. The

principal objective of

this

program,

which was

supported by these ag e

ncies,

was

to

develop

informatio

n

necessary to establish

specifications

for cellulose

acetate film of

commercially

p

rac

ticable

qualit

y

that would have the maximum

stability for lamination.

2 Pro

perties of an Ideal Lamin

ating

Film

An ideal lam

inating

film

could be described as

havingthe following properties:

1) t should

be very flexible, and

abl

e to

withstand

all of the flexing orfolding that

is

re

quired of a pa

per

during use.

2) tshould be considerably

stronger than

the

E

aper

it

protects. Most papers that migh

t

be

und in

repositories exhibit an

elongation of

about percent

up

on rupture. Therefore, in

order

to

protect the body

of the

docu

ment, the

film should show

satisfactory strength at

an

elongation of less

than percent. As a

practical

consideration,

the

film should

be strong

enough

to make reinforcement with tissue unnecessary

a

nd,

if possib

le, to

eliminate

the use of cloth on

maps

a

s

a

part of such laminates.

3)

t should have consi

derable

elongation

beyond the yield point on

a stress-strain

curve,

as a high edge

tear is usually

a

ssociated with

high elongation.

By

lea

ving a narrow margin

o

f film around t

he

edges of the

laminate, a strain

at theedge would result in elongation

of the film,

F

igures

in brackets indicate

the literature references at

the

e

nd o f this

monograph.

but notin damage to

the

paper

.

4) t should be resistan

t

to abrasion.

5)

t

should be

resistant to degradation.

The

film should

be inherently stable

and

resistant to

any environmental conditions

that

it

could

reasonably

be

expected to encounter.

6) t sho

uld

be

possible

to

attach the

film

to

the

paper

with a minimum

of effort, preferably at

room

temperature, either in a small shop

without

special

equipment or in a large

shop using ma

chinesfor

greater

product

ion.

7 ) t should be p

ossible to

remove

the

film

from

the paper, if this

should

become necessary,

with a minimum of effort and

without

damage

to the paper.

8)

The film

should be

transparent to

light

throughout

the visible spectrum and prefe

rably

into the infrared and ult

raviolet.

At present there

is

no known

film

that com

pletely meets all these

requirements, although a

prop

erly formulated

cell

ulose acetate fi lm

repre

sents a

good

compromise. Resistance to a

brasion

and transmission of light w

ere

n

ot

included in

the

work

reported

in this

paper.


8/28

3 Propertie

s of Cel

lulose

Ac

etate

La

minating

Film

3

1

S

tabilityof Cellulose

Acetate ilms

The

work

on

the degradation

of

cellulos

e acetate

filmcon

ducted

in the

course of this investi

gation

has been published

elsewhere

[2

], and

only

a

sum

mary of the

mostimportan

t

find

ings will

be

given

here. Sever

al commercial films

and

laboratory

films

were

degraded

at

elevated temperatures

in

oxygenor nitro

gen,

and the

reaction was

followed

by

determining the intr

insic visco

sity

of speci

mens

at intervals. Int

rinsic fluidity was calcu

late

d from intri

nsic viscosity, and the

slope of

the

plot

of intrinsic flui

dity against time w

as

taken

a

s one criterion

of

degra

dation.

The

num

erical

value

of in

trinsicfluidity incre

ases with degrada

tion.

Two cellulose a

cetate filmswere selected

for

intensive

studjra plasticized fi lm and

an

experi

mental

unplasticized film. The

c

hange in intrinsic

fluidity of the

p

lasticized

film

with time wa

s

studied

at

temperature

s ranging

from 60 to

177

C, and the u

nplasticized film

was

studied at

temperatures

ranging from 110

to 17 6 C.

Deg

radatio

n was principally oxi

dative

in

nature, and

moisture did

not appreciably af

fect

the

degrada

tion under the e

xperimental c

onditions

that

were

us

ed.

Typical

plots for the degradation

of a ce

llulose

acetate film in

moist

and dry

oxygen

are

gi

ven in

figu

re

1.

A sl

ow

initial

reaction

is

follow

ed

by a

0 5

9

3.0

FIG U R

E 12 .

A

n

u

nplasti

cized ce

llulose

ace

tate

fi

lm

m il

thick ha

ssu f

ficien t

flex

ibilityfo r

archiv

al pu

rposes

.

How

ever,

as a pla

sticize

r is r

equire

d ini

tially to

achi

eve lam

inatio

n, the

prop

erties of

fi

lms

t

hat

h

ave lost a

n a

pprecia

ble

am

ount of pla

sticize

r

s

hould b

e ex

amined

. U

nfort

unately

, h

eating a

film

at a

temp

eratur

e

h

igh no

ug h

to ev

aporat

e

the pla

sticize

r w

ithin

a

rea

sonabl

e leng

thof

time

als

o

may ca us

e

p

hysica

l c

hanges

in t

he fi l

m . In

orde

r to

avo

id thi

s as

mu

ch

as possib

le t

hreefi l

m s

wer e

heated

at

50

C

in

activated

charcoal.

The

latter

ab

sorbs

the pla

sticize

r a

nd

greatly

a

cceler

a

tes

the plast

icizer

loss.

Data

o

n weigh

t

loss

and

dim

ensio

nal cha

nge are

giv n

in

table

1 and

the

d

ata ondimen

sional

c

hangeare

plotte

d

in fi g

ur e 15 .

The

plot of

shrin

kage

agai

nst

w

eight

loss

in

figure 1

5 gi v

es a

f

airlys

traigh

t line

for

the three

film s.

It

appear

s that

sh

rinkag

e is

a functi

on of

w

eight

lo

ss

r

egardle

ss

of t

he ty

pe of plastic

izer.

10

O.I

5

0.01

SECANT 0

TO

25

LOSS

E23

kcol

F

I G U R E 1

3.

Th

e weigh

t los

s

v

alues

for

film s n

umbers

4 a

nd

7

in tab

le r

eprese

nt

a

bout

halfof

t

he

p

lasticiz

er

o

riginal

ly in

the fi lm s.

As

th

e

rat

e of

p

lasticiz

er

lo

ss bec

om es

very

low atth

is poi

nt,

the

s

hrinka

ge

valu

es

for

unla

minate

d films would

not

exceed

tho

se

in

table

for ma

ny years.

As th

e pa

per

and

tiss

ue, if p

resent

, o

f lami

nated doc

ument

s

would

ten

d to ho

ld

the

cellu

lo se

acetat

e

film in

plac

e and

pre

vent full shrin

kage,

and

as th

e pro

ce

ss woul

d occu

r

ov

er a

peri

od of

m

any yea

rs,

enough

creep

of

the

film

shouldoccur

to

relieve

any

strain

d

ue to

pote

ntial

shr

inkage

. There

fore,

sh

rinkag

e sho

uld no

t bea pro

blem.

Da

ta

o

n

the shr

inkage

of

lamina

ted sp

ecimen

s

o

f bon

d p

aper aft

er

ag

ing

in ac

tivate

d

c

harcoa

lat

50

C are

giv n

in ta

ble 2.

It is

obv

ious

that

tissue

redu

ces

the shri

nkage

to a

rem

arkab

le

d

e

gree.

T

here

is

co

nsider

able

dif f

erence in

s

hrink

ag e betwe

en

the

long

and

the

short d

irection

s of

th

e specim

ens. Th

isi

s p

robabl

y

due

to dif f

erence

s


13/28

N|

o 0

.2

> -

e n

L

O.I

or

0.05

0.02

SE C

ANT, 0

TO 25 LO SS

EI6

kCOl

SL O

PE AT 50 LOSS

42

kCOl

TA

BLE 1.

lOV

'K

FIGURE

1 4.

,2.0

FIGURE

15.

Weight

lo ss

:

A fter 5 days.

A fter 1 6 d

ays.

After

46 days.

Shri

nkage:

A

fter 5

da

ys..

After 1 6 days

After

46

days

_ .____- _

d o

.

.-......_..

do.

..

............do...

......

.do....

..........do-

C o m m

ercial

fi lm N

o .

4

6 . 5

8.9

10.7

1 .6

3

1.95

2.69

Commerc ial

film N o . 7

10.0

10.8

12.3

2.29

2.27

2. 76

Experi

mental

film*

1.5

1.9

3.6

.48

.51

.96

Made

with cellulose a

cetate f lake

A ,

de scribed in

table

4,

andcontainin

g

2

0-percent triphenyl phosphate,

based o n we

ight

of fi

lm .

TABLE

2.

Lamina

te tested

P

aper edge to edge:

C ross dire

ction

__

_ _ _ _ _ _

_

___

.___

Machine direction

__

_________

.

Film edge to

edge: b

Machi

ne direction...

________

______

Paper e

dge

to

edge:

Cross direction

,__________

Machine

dir

ection.....--___ ..........

Film and

tissue edge

to

edge:

b

Percent

shrinkage

after aging

in

ac

tivated

charcoal

at 60 C for:

0.6

.2

.6

.4

.2

.0

.2

.2

50

0,8

.2

.

8

.4

.4

.0

.4

.4

Data

were

obtaine

d by James

G e

ar,

National

Ar c h

ives

an

d

Records

Service. Specim

en s were approximately 1 4 X

23 cm .

The film,

o r

film and

ti

ssue,

o f the laminated

specimens extended

abou

t

0.3 cm beyon

d

the

edge o f the pape

r.

in the machine

and

cross

directions

of

the paper.

Stress-strain dat

a and folding en

durance data

have been

obtained

on

the

films

heated

in char

coal and are

given intab

le 3.

N

one

of the

p

rop

erti

es of

inter

est

in an

archival film ha

s changed

enough to

be consid

ered significant.

The experi

mental film plasticize

d

wit

h

triphenyl

p

hosphate

show

eda

significant decrea

se

in

elo

ngation

at

b

reak and energy

to

ruptur

e. Th

e

former

is no

t

particular

ly important,

but itis tied u

p with

the

latter,

wh

ich, it

is

fel

t, is impor

tant

in

determinin

g

edge tear. However,

this

formulation is

not

re

presentative of archival

films.

3.3.

P

hysical P

roperties o f Ce

llulose Acetate

Films

Th

e

physical

properti

es of a cellul

ose

ac

etate

l

aminating

fi

lm are fa

irly closely defined

by th

e

plastic

izer req

uirement. An unp

lasticized fi

lm

h

as a

very

high

softening tem

perature,

and

it

is


14/28

TA B L E 3

.

Film

de signation

Film

No. 7 :

Heate

d

in eharc

oal___-____-_

_-

Fi

lm

No.

4:

C

ontrol. _.--

-._.-. .-----_ _ _ _ -

Hea

ted

in charcoa

l ._._..__._

..

Experim

ental film

:

Control-

- . _ __

_

Heate

d in

charcoal

_ _ _

_ _

T en

sile

at

break

2.1

2.3

2.0

2.0

2.3

2.3

Elonga

tio n

at break

26

23

21

23

15

5.5

Yield

strength

2.0

2.2

1.9

2.0

2.3

2.4

Elong

ation

at yiel

d

point

3.6

3.7

3.9

3.7

3.3

3.2

Energy

to rupture

5.01

4.86

3.

85

4.26

3.30

1.11

Foldi

ng

enduran

ce

MI

T 1-kg

tension

1,444

1,863

1,04

7

1,105

1 136

89

9

Made with cellulose

ac

eta te flake A

describe

d in tab

le

an d

c

ontaining

20

-p ercent

triphenyl

phosphate

based

onweigh

t of film.

necessa

ry

to

f

ormulate

the cellulo

se

ac

etate

with

an

active

solven

t plastieiz

er inorde

r to reduce

the

s

oftening

tempera

ture

enoug

h

to

allow

lam

ina

tion

w

ithout

damage to

the

film or the d

ocument

.

A typical

l

oad-elong

ation curve

for plasti

cized.

cellulose

ac

etate

i

s shown

in

figure

1

6. The

load

is t

he pull

in kilo

grams on a strip

of film

in an

automa

tic

rec

ording tensile

te

sting

ma

chine

a

nd

the

elo

ngation

is the

am

ount

of st

retch

as the

pulling force

is applied.

Th

e first

part of

the

curv

e

up

to t

he

y

ield point

mostl

y repre

sents

elas

tic

behavior

and

if the

loa

d

were

re

moved

the film

wo

uld esse

ntially go

bac

k

to

its

original

length

.

If

the

load is

remov

ed beyond the

yield

point

an

d before th

e breaking

stren

gth

is r

eached

the

s

pecimen will

hav

e a

pe

rmanent

set

and w

ill

not

g

o

bac

k to its

original

length.

The

elongat

ion

of

pl

asticized

cellul

ose a

cetate

f

ilm is

approx

imately 3

percent

at the y

ield poi

nt.

The extent

to w^ h

ich pape

r

m

ay

be

elonga

ted

witho

ut r

upture

varies

wi

th the paper

and

with

the

direc

tion of

s

tretch

b

ut is us

ually between

and

4

percent. Therefore the elongation

of

the

pape

r and

the

elongati

on

of

the

f

ilm

that w

ould

b

e

useful in protec

ting

thebody of

the d

ocument

are

fair

ly well match

ed.

The ar

ea under

th

e

l

oad-elon

gation

curve is a

fu

nction of

the

energy

requ

ired to rup

ture the

20

spe

cimen and

is

a

measure

of

th

e to

ughness

of the

film.

Before

fu

ll

adva

ntage

c

ould be

t

aken of i

ts

toug

hness

the

f

ilm

would h

aveacq

uired

a

perm

a

nent

setand the

p

aper

would

havebee

n

tor

n.

M

any

properti

es of films

such as edge

tear

tough

ness

t

ensile st

rength an

del

ongation

depe

nd

on the

cond

ition

of

the

e

dge of

the fil

m.

A

smal

l

defect

or notch can result

in

considerable impair

ment

of film

pro

perties. Pl

astic

films in gen

eral

have

a high

edg

e tear in

co

mparison

with

inter

nal

tear

which is

usually

ver

y

low

.

Phy

sical test da

ta were

obtaine

d on

seve

ral

e

xperimen

tal

film

s an

d comm

ercial

films. Wit

h

one

ex

ception

the ex

perimen

tal films

were

plas

ticized w

ith

20-per

cent

d

imethyl

phthala

te an

d

wer

e

cast from a

soluti

on of 16

-g

c

ellulose

acetate

and

4-g p

lastieize

r in

18

0-ml

acet

one and 20-m

l

m

ethyl

alcoh

ol. Flake

was

dissolved

in

18

0-ml

m

ethylene

chloride

and 20

-ml methyl

alcohol.

All

films were

conditioned

at

23

C

and 50-percent

r

elative

humi

dity f

or at least

two days

before

testing.

Edge tear \vas

dete

rmined

acco

rding to AST

M

method

D

1004 on spec

imens cut

with

a special

die a

nd

is the forc

e i

n kilog

rams required

to

start a tear

in the s

pecimen.

Fo

lding end

urance

data we

re

ob

tained

with

an

MIT

tes

ter at 1-kg

tens

ion acco

rding

to T PPI

S

tandard T 42

3.

T

ensile

load-

elongatio

n

da

ta were

obtaine

d

\vit

h a

co

nstant-ra

te-of-stra

ining

mac

hine

wit

h a

n

initia

l

jaw

separatio

n

of

4 in

. The rate

o

f m

otion

of the

crosshea

d wa

s 2 in./m

in.

A

modi

fication

of

ASTM

D 903,

Peel

or

Strippin

g Strength

of

Ad

hesives

[16], was

used

for

the evalu

ation of l

aminatio

n

efficiency

. A

sh

eet

of

comm

ercial cel

lulose acetate

lamin

ating

fi

lm was

lam

inated

betw

een two

sheets of a

stron

g

hard

b

leached

suJfate pap

er

3

with

the p

aper

F

IGURE 16.

Dat

a

were

obtained

by Russell

J. C

apott.

3

Made

in the

paper mill at

the Nation

al Bureau of

Standards mill run

No . 1882


15/28

extending about 10 cm

beyond the film at one end

of

the

sa

ndwich.

Strips

15-mm wide were

cut

from this sandwi

ch, andone end of

each strip

of

paper was placed in

the

clamps

of an

automatic

recording

tensile

testing

mach

ine.

The

load

value

a

t the

b

eginning of failure

was alw

ays

the

h

ighest, failure

occurring

b

etween the film and

one

strip of pape

r which then tore and

feathe

red

out to rupture.

P

hysical test data on

severalexperimentalfilms

and

commercial

films are g

iven intable 4. The

degree of

substitution of the ce

llulose a

cetate

samples

varies

from

2.31 to 2.68

and the viscosity

varies over a wide range, but

most of the physica

l

propert

ies fa ll within

fairly

n

arrow limits.

The

commerci

al

c

elluloseace

tate films have a higher

elongati

on

at break th

an the expe

rimental

f

ilms

an

d

a

much

higher

energy t

o rupture.

Som

e

of

the expe

rimental films

ga

ve consider

ably lower

folding endurance values

than

did the

commercia

l

films.

The unplasticized experi

ment

al

film

exhibited an unusually high

folding

endurance, indicating

that

cellu

lose a

cetate films

1-mil

thick donot depend

on plasticizers

for

flexibility.

Unplasticized cellulose

acetate films

3-mils

thick may

exhibit a folding end

urance of

several

hundred double-folds

[15],

In

order

to

ob

tain

an es

timate of the intrinsic

fluidity at

which a cellulose

acetate film

is

no

lo

nger useful, spe

cimens of commercial

film num

ber

4

were

aged in oxyg

en for

8,

16,24, and 40

hr, and in nitrogen for

24 and

40

hr. Intrinsic

fluidity values

and load-elon

gation data

ar

e

given

in

table 5 and t

ypical load-el

ongation

curves are gi

ven in figure 17.

There

ar

e no signif-

T A B L E 4.

M

aterial

tested

De gree of

substitu

tion

Vis

cosity

T

ensile

strength

at

break

Elonga

tion at

b

reak

Yield

strength

Elonga

tio

n at

y

ield

Energy

to

rupture

Folding

endurance,

MIT, 1-kg

te n

sion

Edge tear

(ASTM

D

1004)

Thickne

ss

Experimental film b made with cellul

ose

ac

etate

A__

______ ______ ______________

B_______

_ ________________ _____

c

D._ _

_ _ _ _ _ _ _ _ _ _ _ _ .

______________

D b_________________

__________

E

F

G. _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ __ _ _ _ _ _ _ _

H _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

I_ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

J___.

_ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

2.44

2.68

2.31

2.41

2.41

2.49

2.41

2.40

2.41

c51

d 16 5

04 1

o69

69

23

30

044

-62

2. 0

2.5

2.4

2.5

3.0

2.3

2.0

2.5

2.4

2.4

6.2

5.4

6.4

8.3

4

.3

7.4

6.5

6.2

7

.3

5.9

6.8

2 .0

2.5

2.4

2.6

3.0

2.5

2.2

2.1

2.6

2.5

2.5

3.1

3.1

3.2

3.2

3.2

3

.2

3.1

3.0

3.3

3.2

3.2

1

.0 3

1.18

.34

.90

1.10

.56

.20

1.15

.70

1. 30

1.49

511

91 9

50 6

80 6

1,393

73 2

92 2

1 ,14

8

75 0

84 6

1 ,29 7

20 5

10 5

90

135

11 5

85

16 0

11 5

17 0

90

1.5

1.5

1.5

1.5

1 .1

1.5

1.5

1.2-1.5

1.5

1

.2

1.

2

Co

mmercial films

Cellulose acetate:

Xo.4. _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

X

o.

7_

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

No.

8

. __

______ ___

_ _ _ _ _ _ _ _ _ _ _

Polyethylene terephthalate

Polyethylene _ . _ _

_ _ _ _ _ _ _ _ _

1.9

1.8

2.0

2.5

0.9

19.6

20.9

15.8

50.2

16 5

1 9

1.6

2.0

1.9

0.5

3.4

3.4

3.4

3.4

11.4

3.44

3.33

2.94

11.4

13.1

1,007

1,419

1,638

>200, 000

(*)

75

65

70

30 0

17

0

0.9

.9

.9

.5

1.5

Data

were obtained with 1 0 specimens

cut in the lon g direction of

the

film.

b All

expeiimental films

contained 2 0 percent by

weight

of dimethyl

phthal-

ate, except

D*

w

hich

wa

s unplasticized.

o ASTM

methodD 871, solvent A ,manufactu

rer's data.

ASTM

D

871, solvent C,

manufacturer's data.

e ASTM method D871, solvent B ,

manufacturer's data.

f

Test

discontinu

ed

after 200,0

00 folds.

e

Spec

imens elongate

d

too

mu

chto

obtain

fold

data.

T A B L E 5

.

Trea

tment of film

Untreated.--. _ _

_..____

Nitrogen

a

t 124 C:

2 4 h r - _ _ _ _ - ~ _

--..-_

_ _

40 h r . _ _ _ _ - - - _ _ - _ _ _ -

_____________

Oxygen at 124

C:

8 hr__

_ _ _ _ _ _ -__---_

_ _ _ _ _ _ _ _ _

16 hr________-_ - -_______

_ _ _ _ _ _ _ _ _

24 hr, ____ .__ .____ - . - ____ -_ .______

T

ensile

at

br e

ak *

1. 8

1.4

1.7

1.5

1.5

0.9

Elongation

at

break

11.2

6.5

13.9

11.9

4.0

1.0

Yield-

strength

*

1 .8

1,4

1.6

1.5

1.5

Elongation

at yield*

3.5

3.0

3.0

3.2

2.9

Energy

to

rupture*

1.86

0.98

2.10

1.68

0.51

.0 6

Intrinsic

>

fluidity

0.59

.6 3

.5 8

.6 6

.7 5

1.12

'Average for

20 specimens.

b

A

verage

for 3

or

4

specim ens.


16/28


17/28

the acetate

flake,

a

nd is the

softening point

depression

constant

for

the

p]ast

icizer.

Usi

ng

this equation,

the softening temperatures

of

four

of the mo

re

prom

ising

films

were calculated,

and the

data

are

given

in

table

6. Thes

e data

suggest that a softening temperature

near114 C

would

be desirable, as

the

first three films

laminate

satisfact

orily while

the last one does

not.

The

degradation of

film

and

paper

duri

ng

th

e

lamination

process was studied

on

th

ree laminating

press

es

in

the Washington

area.

Specimens

of

film of

prop

er weight

for the viscosity test were

placed

in

folds

of

aluminum

fo il

and

run through

the presses. Two

comm

ercial

films s

howed no

mea

surable

change

in v

iscosity

even after

20

p

asses in a press

.

Samples of

rag

paper were run through

the

pres

ses in

the

same manner as the

films, except

t

hat the

a

luminum foil

was omitted. The paper

had a

of 4.9, cold extraction.

Some of

this

paper was tr

eated

with

alumto give a

of 3.9,

cold extra

ction.

Viscosity m

c

uprammonium

h

ydroxide solution was determined

before and

after the

specimens hadbeen run through the

presses, and the

degr

ee of polymerization

calculate

d from the viscosity d

ata.

The

data

are

given in table

7.

TA B LE 6

.

TA B

LE 7.

Film

designation

Softening

temperature

113.5

117

114

1

27.5

Softe

ning

temp

eratures were

calculated using

the

equation:

see

p. 10)

.

t> Composition of film

No. 2:

7 3 percent cellulose aceta

te

fla

ke

E ,

5

percent

tri ph

enyl phosphate,

2

percent

dimethyl phthalate

,

0.5 percent

magnesium acetate

te trahydrat

e,

1.0

percent resorcinol monobenzoat

e,

0.5 pe rcent di-tert-butyl

p-cresol.

Composition same as No. 2 except that the film

contains 1 5 percen t

d

i

methyl pht

halate an d

7 8 percent cellulose

acetate.

Films Nos

.

and

3 were

supplied by W . D. Paist of

Celanese Corporation of America.

The

untreated spe

cimens do

not show an appre

c

iable change after on

e

pa

ss in anyof the

presses.

There are

definite cha

nges

after 20

passes, both in

and

in

co

lor.

The

color

changes

show go

od

correlation

with the

changes in

The

specimen

s

trea

ted

with alum

togive a

of 3.9 show drasti

c deterioration e

ven after one

pass. The tests were made

a few weeks

after

the papers

w

ere

treated, and it is

obvious that

some d

egradation occurred at r

oom

tempera

ture.

Enough

acid

was

released

during

the short time

in

the

press to degrade the cellu

lose to

its

leveling-off

degree

of

polyme

rization. A graph illus

trating

the

latter is

shown

in figur

e

19.

Type

of

press

Flatb

ed

Cylindrical-

Cylindrical-,

Num

ber

of

passes

in

press

/ 0

5

10

20

1

4

5

10

20

1

5

10

20

Paper 1119B *pH4.9

Degree

of poly

meriza

tio

n

b

720

65 0

598

53 8

Color

White. .

Slight

yellowin

g.

Slight

yellowing.

Distinct

yellowing.

Slight

ye

llowing.

Yellowing...

Distinct

yellowing.

Paper

1119B with alum

added,

pH

3.9

Degree

of poly

m

eriza

tion

>

. 5 0 9

28 7

235

235

306

235

273

168

Color

White

.

Slight

yellowing.

Yellow and

brittle; many

breaks.

Brown;

very

brittle.

Very dark; very

brittle.

Almost

b

lack.

Black.

Almost black.

Black.

Pape

r 1119B

was made

in theNBS paper mill from a mixture

of new

and

old

rags;

it

contains 1.5-p

ercent

rosin

and 1.5-percent alum.

b

Thedegree

of

polymerization is t

he number

o

fanhydroglucose units per

cellulose

molec

ule.

2

T

IME

FIGURE 19.


18/28

Cellu

lose i

skn

own

to c

onsis

t of

cry

stalli

ne and

amo

rpho

us

a

reas

.

Alth

ough

th

e a

morp

hous

are

as

a

re a

ccess

ible

to wa

ter

a

nd

ac

id

a

nd a

re ea

sily

hydro

lyze

d, th

e

cry

stalli

ne are

as are

not

p

ene

t

rated

by

w

ater. T

he h

ydro

lyzin

g,

or de

poly

-

meri

zing effec

t

of acid

is ver

y rapid

in

the

amo

r

ph

ous

areas

bu

t, as

the

acid

pres

uma

bly ca

n act

o

nly on t

he

surfa

ce of t

he

cr

ystal

s, the

actio

n

on

th

em is

ver

y

s

low.

The

valu

e

tha

t

pr

evails

w

hen th

e fast

re

actio

n

i

n the

amor

phou

s are

as i

s

o

ver and

o

nly t

he slow

r

eacti

onw

ithth

e crys

tals is

oc

curri

ng is

term

ed the

leveli

ng-of

f

T

he

lev

eling

-off

o

f co

tton i

s abo

ut

200

to

2

50.

W

ood

pu

lps

m

ay

b

e

h

ighe

r o

r

lowe

r

dep

endi

ng on

th

e sou

rce a

nd re

gene

rated

cellul

oses

us

ually

ru

n

fro

m 15

to

60 .

The

dat

a ob

taine

d show

that

paper

s con

taini

ng

acid

canbe

seri

ously

d

egrad

ed dur

ing la

mina

tion.

La

mina

tion

does no

t d

egra

de film

o

r p

apers

that

con

tain litt

le

or no ac

id.

T

issue

lias

b

een u

sed

fo

r y

ears to s

treng

then

lami

nated

d

ocum

ents

.

orde

r to

d

eterm

ine as

q

uant

itativ

ely

a

s possi

ble t

he a

ctual

con

tribu

tion

o

f

tiss

ue to t

he

pro

pertie

s

of

a

lam

inate

, sev

eral

sp

ecim

ens w

ere

la

mina

ted a

ccord

ing to

a p

rede

ter

mine

d

p

atter

n.

Pap

er,

f

ilm,

an

d tis

sue ar

e all

anis

otrop

ic in n

ature

; that

is, the

p

hysic

al

pro

p

erti

es depe

nd on

the

direc

tion

of

me

asure

ment

.

Ho

weve

r as

the

fi

lm is on

ly mi

ldly

aniso

tropi

c,

the

fi lm

direction

was

kept constant.

T

he pa

pers u

sed

(ta

ble 8) w

ere

selec

tedb

ecaus

e:

(1 ) th

e aci

d conte

nt w

as to

o

small

tocause

de

gra

dati

on

duri

ng lam

inat

ion,

and

2

) t

he pa

pers

w

ere

very

w

eak esp

ecial

}

pa

per

1

216, a

nd any a

dvan

tag

e

of

tis

sue

re

infor

ceme

nt shoul

d b

e mor

e a

p

pa

rent.

C

omm

ercia

l

fi

lm N

o.

7 was

u

sed

in th

ese

exp

erime

nts.

T

ABLE

8.

a

Co

mpositi

on and

properti

es

Fiber..

_...._

..,.

_ _ _ _

Filler^.

_____ _

_ _

Ros

in........

..

_ .

A Ipha

cellul

ose

.._._.

_ _

Th

icknes

s....

_--

.

Fo

lding

end

urance M

IT,

0.5 kg ;:

M

achine

directio

n- _____

___

__dot

Cross

di

rection

.

__.-

-

..do

_

do.

do .

ihle folds..

.do

P

aper

1214

Old

r

ag

None

1 . 1

0.5

90

.3

6.2

3.8

52 4

26 7

Pape

r

12

10

Old r

ag

28. 2

None

None

92.7

9

.5

3

.3

28

2

5

The

se

pap

ers

were

made

in NBS p

aper mill

.

>

P

recipit

ated calc

ium

carbon

ate.

T

he lam

inatio

ns w

ere p

erfor

med

by p

erson

nel

at

two

d

iffer

ent ag

enci

es o

ne of

wh

ich u

ses a

stea

m-he

ated

fl

at-be

d hydr

aulic

pre

ss an

d the

oth

er a

cyli

ndric

al p

ress

wit

h

e

lectr

ically

hea

ted

pr

eheat

er

plate

ns. L

ami

natio

ns

o

n

th

e hydr

aulic

press

were

done

at

a

pressure

of

300

lb/in.

2

with

ste

am

appli

ed

to

t

he p

ressfor

135

se

c.;

the

stea

m

pr

essur

e

r

ose

to

a

bout

7

4 Ib

(1 52

C) i

n

a

bout

1

m

in.

The

p

ressu

re use

d o

n th

e cyl

indric

al typ

e

p

ress w

as

not

me

asure

d. Th

e lam

inatio

n

sand

w

ich

wa

s

kep

t

in th

epreh

eater

20 to 3

0 sec

. bef

ore

it

wa

s pa

ssed

thr

ough

the

unhe

ated

pres

sure

ro

llers

.

From

previ

ous

m

easur

emen

ts, it

is

est

i

ma

ted t

hat

the tem

per

ature

of t

he pr

ehea

ter

was

a

ppro

xima

tely

182

C.

12

A mo

dific

ation

of

the Fin

ch

e

dge-t

ear devic

e

(

TAP

PI

stand

ard T

470)

wa

s d

evelo

ped for

the

eva

luati

on of

edge

tea

r. T

he F

inch

d

evice

is

use

d in

th

e lower

jaw of

a te

nsile

mach

ine,

and

c

once

ntrat

es the s

tress

on

each si

de

of

a

test

stri

p

of p

aper

. T

hem

odific

ation

co

ncen

trates

t

hestre

ss

a

t

only

one

ed

ge

of

the spec

imen

.

Th

e Fin

ch

atta

chm

ent

and

the m

odif

icatio

n a

re

s

hown

in

fig

ure

20. Th

e low

er

end

of

t

he spe

cime

n

is

clamped behind

a

Jj J-in .

thick metal

angle

that

is

a

bout 2

2} fro

m

the

hor

izont

al. Th

e tea

ring edge

was

dre

ssed

t

o a

hig

hly po

lishe

d h

alf-ro

und.

T

he

dim

ens

ions

ar

e p

urely

a

rbitra

ry

as an

y

edge

-tear

tes

t is

a

m

odifie

d

tens

ile

te

st

wi

th

a

hig

h

str

ess

conc

entra

tion a

t th

e edg

e

of the te

st

spe

cime

n.

B

ecaus

e of e

longa

tion

of

the

speci

men a

n ed

ge-

tear

v

alue

will

depe

nd on t

he ang

le o

f the

tear

ing

d

evice

as

the

an

gle

deter

mine

s the

stres

s

conce

n

tra

tion

a

t th

e

e

dge

A

zer

o angl

e

woul

d

c

orre

spo

nd

to th

e usua

l te

nsile

test

.

D

ata

o

n

the

effec

t

o

f

w

idth o

fe

xtens

ion o

f film

or

of film

plu

s

tissu

e on

ed

ge

tea

r, us

ing

the

mod

ified

F

inch

a

ttach

men

t, a

re g

iven i

n

table

9

.

Th

e widt

h of

ext

ensio

n

of

film

o

n th

e pap

er a

nd

film

laminate

is

not

critica

l a

bove

1 m

m. If

the

film

does

not

exten

d bey

ond th

e edge

o

f thep

aper

,

th

e edge

t

ear

is consi

derab

ly l

ower

. Th

e

wid

th

of

exten

sion o

ffilm

p

lus tis

sue o

n the

lami

nate

of

pa

per,film

a

ndtissu

e

is

no

t

critic

al.

It

is obvio

us

tha

t tissue

d

ecre

ases

the

edg

e

tear

of

a

lam

inate

.

The v

alues

in

th

e

l

ast

co

lumn

are

con

siste

nt wi

th

th

e

valu

e

for

the edg

e t

ear

of film

and

tissu

e.

I

t

mus

tbe

emp

hasiz

edthai

the

lam

inat

esc

ontai

ning

tiss

ueh

ave

a

hi

gher ed

ge t

ear th

an

the

pap

er alon

e.

L

abor

atory

d

ata

are

n

ot

avai

lable

on

the ab

ra

s

ion

resi

stanc

e

of

doc

umen

ts

l

amin

ated

wit

h an

d

with

out

tis

sue.

Res

istan

ce to

e

dge

tear

does

no

t

ne

cessa

rily

cor

relat

e

w

ith

resi

stanc

e to

abras

ion at

the

edge

of

the laminate.

Data

o

n

tensil

e stren

gth, e

dge

tea

r, inte

rnal

t

ear, and

el

onga

tion

at brea

ko

f pap

er, film

tis

sue

a

nd vario

us

c

ombi

natio

ns

o

f film

wit

h pa

per

and

tis

sue are

given

in ta

ble 10

. T

he data

show

fe

w

sig

nifica

nt i

ntera

ction

s. T

here

is

no

sig

nifica

nt

in

tera

ction

betw

een

the

v

alues

for

film

a

nd

pape

r

an

d

the la

mina

tes of

fil

m a

nd

paper

. How

ever

c

onsid

erab

le intera

ction

occu

rs

when

t

issue

is

adde

d

to th

e lam

inate

.


19/28

UPPER CL MP

SPECIMEN

t 5mm WIDE

TA B LE

10.

UPPER CLA M

P

SPECIMEN 5m

m WIDE

CL MP

OPEN

SP CE

FIGURE

20

(a )

(6)

TA B

LE

9.

a

Width

of

trim

0

1

2 _ _____

3.

.____.

4

_______.

6 _______

8 _.___

.

2 sheets

film

N

o. 7

laminated

2 .1 0

Pape

r

only

0

.14

Tissue

and

film lami

nated

0

.4 1

Pa

per an

d

f

ilm lami

nated

1.04

9 79

O

QA

3

.18

3.13

3.08

2 .

31

Paper,

film,

and

tissue lam

inated

0.50

.41

,41

.41

Oft

.

41

.4 1

D

irection

T

- >

T

- >

t

-

->

t

- >

t

->

t

-

-

-

ft

J J

H

I

t

3

->

i

ft

I

Tens

ile

strength

Edge

tear,

modif

ied

Finc

h

Internal

tear

Elongation

at

break

%

Film only

2 .0

1. 5

1040

)

3.0

3.0

14

.0

28.5

Two sheets

of

film

laminated

e

F

3. 7

< o

1.5

F

21 00

C

( e )

F

9.9

C

17.2

F

25.8

C

1.9

Tissu

e only

2.1

0

( f )

( f

)

12 .0

( )

2.3

(0

Film

and

tissu

e laminated *

10.0

3

.4

6 .8

9.2

2.0

6.6

415

425

445

315

410

31 5

2 9.0

56

.0

40.2

34.0

57.0

44.0

3.

7

17.4

3.3

3.3

1.2

3.3

P

aper 1214

only

5.4

3.4

295

26 5

41.7

45.2

2.5

3.7

Film and

paper 1214, lami

nated

*

7

.4

5. 6

8.4

6.4

2050

280 0

1000

860

52 .1

5

2 .4

e

)

()

3.4

7. 1

2.9

6 .1

Film

,

tissue

and p

aper

1214

, laminated

15 .0

8.7

6.6

11.7

13.2

10.1

16.1

9.5

6.9

12.9

13.7

10.5

500

420

415

36 5

395

540

410

36 5

365

410

365

36 5

88.0

7

7.6

6 8.8

81.8

93

75

11 2 .0

82.0

73.0

90.0

100

86

3.7

3.7

7.0

3.4

3.7

3.6

3.8

2.6

4.7

3.

5

3.8

3.7

Paper

1216 on ly

2.7

1.9

135

180

26 .8

29.6

2.2

3.5

F

ilm and paper 1216,

laminated *

5.4

4. 9

8.4

6.4

3550

3150

100 0

86 0

37.9

38.3

e

)

( e )

5

.4

10.3

3.

2

5.5

Film, tissue and

paper 1216, la

minated

13.2

6.8

6.0

9.3

12.1

8.9

12 .7

6.4

5.5

10.2

12 .4

1

0. 5

475

410

540

455

45 5

540

410

315

315

365

36 5

36 5

84 .

6

64.0

68.0

80.6

88

78

86.0

68.0

66.0

8LO

89

79

3.7

3.7

7.0

3.5

3.7

3.7

3.8

2.6

4.8

3.3

3.7

3.3

A rrows

indicate m

achine direction and

cross

direction

of the film,

tissu

e

or

paper; arrow is s

hown

for

each sh

eet. Vertical arro

w in

dicates machine

direction

,

horizontal arrow i

ndicates

cr o

ss dir

ection.

> These data

were not

obtained.

Lam

inated on aflatbed press.

* Laminated

on

a c

ylindrical

type press.

Insufficient sam

ple.

Tissu

e

to o

weak

to test.

* The film or

the

fi

lm and tissu

e extended

2~mm bey

ond

edge of

pap

er.

Laminated on a

flatbed

press.

13


20/28

The

values for

edge tear using the modifica

tion

of t

he Finch device

are not

additive

* The

film

ha

s

a high e

dge tear, but wh

en

lam

inatedto

tissue, the edge tear

of the laminate drop

s to a

fraction of

that of the

film.

The data

for internal tear

show an interesting

interac

tion

in

that the sums of the

values fo r tear

of

the

individual she

ets

add up

to

consid

erably

less than

the values for lam

inated

sheets

of

film,

pa

per and ti ssue. A s

indicated

b

y the data tab

u

lated

in

table

11,

the amount

of

interaction

de

pends on

whether one uses the tear

value

of

a

single

she

et

of fi

lm, multiplied bytw o

,

or whe

ther

one uses the value of two lam

inated sheets of film

.

The la

minates prepared on the cylin

drical type

press sh

ow

a

higher numer

ical value

for internal

tear than

those

prepared on the fla

tbed press,

wh

ereas laminates pr

epared on

the

flatbe

d

p

ress

show a

higher edge tear

.

Data on elongation

a

t break follow,

in general

an exp

ected pattern. The

elo

ngation values of

the lamin

ates usually lie betwee

n that of the film

andof the

paper,

ti

ssue, or paper

and tissue.

The values for

the laminates usual

ly

lie very close

to those

of

the paper

or

tissue.

When

thepaper

or tissue ruptures

,this apparently

serves a

s

a

starting point

for a

tear

in the

film.

For the

sam

e

r

eason, the edge tear of

a laminate is much

less

than that ofthe film

and only slightly

higher

than

that

of the

paper.

TA

B L E

11.

Laminate

components

Fi

lm,

2 sheets laminated...

__

..

...

Paper 12 l4 . ____-_ . __ . ___,,.__.__

TissueX2.-_

_ _ _ _ _ _ _

......

...

........

FilmX2

1 sheet=3.0g).._.._

.......

Paper

1214... .

__ ._ ._ ._

_ _ . _ _ _ _ . _ _

TissueX2......_--

_._

E xperimental values

for

paper

1 2 1 4 ,

Film,

2 shee

ts laminated-,....,-,,.

Paper 1216.... .._.

__...._.

..____._

Tis

sueX2.._. ._.........._.......

Sum

......

...-_--.___-_.-

FilmX2 1 sheet-3,0

g)....

.........

Paper 1216.. .

_...

_..

......_.....

TissueX2.-__----_-___. _.__.__

Sum....

..... ... .......

.

.. .

Experiment al

va lues

for

paper

1 2 1 6 ,

film, tissue.

...

_...--

_

-,,-_

Machine direction

ofpaper

and

tissue

F*

41 .7

24.0

75.6

88.0

9.9

26.8

24.0

60.7

8

4, 6

6.0

41.7

24.0

71.7

.

..

6.0

26.8

24.0

56.8

0

17.2

41.7

24 .0

82.9

112.0

17.2

26 ,8

24.0

68.0

86.0

Cr o

ss

d

irection of

paper

and

tissue

F

9

45.2

0

55.1

68.8

9.0

2

9. 6

0

39.5

68.0

......

6.0

45 .

2

0

51.2

.-._..

6.0

29.6

0

35.6

O

A .

4

5.2

0

62.4

73.0

17.2

29.6

0

46. S

6

6.0

Laminated on a

flatbed

press.

La

minated

on a

cy l

indrical

type

pre

ss.

The term deacidificatio

n

as

used in this paper

refers

to the

Barrow

meth

od

of

neutralizing the

acid in paper

by me

ans

of

consecutive wa

shes

with

saturated

solutions

of

calcium

hydroxide

and calcium bicarbon

ate [20].

T w o

p

ractically neutral

papers, containingno

sizing,

filler, or alum, w ere selected f

or

thi

s work

a

cotton

ra

g paper

and

a so

da sulfite wood-pulp

paper. Specimens of these

papers w er

e

treated

with 0.02

sulfuricacid, ot

her specimens w e

re

treated with 1-percen

t alum

solution, and still

others

were

wash

ed with distilled

water. The

data

fro

m the physical

tests

of

the

wat

er-washed

specimens

were used as controls to

compare with

d

ata from the physica

l testing of the

acid- and

al

um-treated papers. Som

e specimens

were

de-

acidified,

a

nd so m e of the s

pecimens w er

e

aged at

124

C

in

oxygen for

24

hr

with

and without

prio

r deacidificaticn. In

addition,

some

of

the

specimens were laminated

and subjected to

ac

celerated

agin

g

i

n orde

r

to evalua

te the effect of

ac

id in

th

e paper and of

deacidification

on

the

film

.

The data

on the pr

operties of

the

paperstested

in

the

investigationof deacidific

ation a

re sum

marized in ta

ble 12. It is obvious that

deacidifi

ca

tion prevent

s

the

degradation

that otherwise

occurs during

acceleratedaging.

14

Data on the degrad

ation of film laminated to

the

acid-treated

and deacid

ified papers are

p

lotted in

figu

re

21.

One line is

drawn through the data f

rom

the

specimens

of

film

laminated

to

alum-treated

paper andthespecimens lami

nated to acid-treated

paper. Also, a sing

le

li

ne appears to

repres

ent

MIN TED TO WATER W

ASHED

PAPER

AMINATED

TO

ALUMTREATED

PAPER

AMINATED TO

ALUM

TREATED

DEACIDIFIEO PAPER

AMINATED TO

ACID TREA

TED

PAPER

AMINATED TO AC I D

RE TED DEACIQtFtCD PAPER

0 5

TIM

DAYS

FIG U B E 21.


21/28

TABLE 12.

Sample

Treatment

Not

aged

pH, cold

extract

Tensile

DP

Brig

ht

ness

A ged in ox

ygen at 1 2 4 C

for 2 4 hr

pH, cold

ex t

ract

Tensile

DP

Bright

ness

*

100 cotton

paper 73 2

l__-_-____.

____

2.... __._..._____.

._

3.

.

._._.. _

4. .

.. ..

1

.......

...

2......-_...-...

...._

3.

..

4...

.......

Not

deacidifled

Wa

ter-washed.....__ _ _ _ _ _ _ _ _ _ _

percent

alum.,

__

_ _

__

___

0.02 JVTHjSO

^..,..

_.

........

6.

2

5

.9

4.5

3.7

8.7

7.7

8.3

6.4

478

477

513

402

_.

71.4

71.7

72.9

6.6

6.4

4.0

3.7

8.0

7.8

(b )

>

455

460

310

31 7

%

66.6

64.6

56.0

19.8

Deacidified

None

___

_ ___

._ _ _ _ _

Water-wa

shed__

__

______

0.02 H

_SO4._..._-______,_,

_.___

9.7

9.

3

ao

9

.2

8.4

7.8

7.7

7

.5

61 1

4

87

51 2

487

71.9

73.5

72.3

74.6

8.0

7.8

8.0

7.7

4

78

473

483

465

67.3

66

.8

70.6

67.9

Sod

a-sulfite

paper

1133

Not

deacidifled

5 _ .._,_._

6......

7..

._...-_..__

.

8.......__....

5... .-.-.,___

.

6_.____.

7

..

_-_.-.-_._....

8

...._.___.___

...

No ne

___

_

_________

_

Water-washed.

__.

...._......

0.02

H. SO4

0 .02 Ha

SO*.....

--

-

--_...-

5

.1

5.7

4.4

3.7

9.0

7.7

7.5

7.5

6.

0

7.4

7.5

7.5

7.4

635

62 4

58 2

41 7

D

eacidified

63

62 5

61 2

KQQ

55.2

57.8

54.4

58.6

57.5

59.3

5

7.5

60.5

5.5

5.4

4.3

3.6

7.3

7.2

2.6

(

b

)

7

.2

7.3

7.1

6.9

51 6

558

35 3

35 6

59 2

62 7

540

51.5

52.8

48.2

23.4

54.9

65.2

55.6

66.3

Reflectan

ce

values obtained

using

the

Hunter

mu

ltipurpose refl

ectometer with

blue

filter.

t V

ery w

eak

and brittle.

the

data

fro

m

the

filmslaminated

to

deacidi

fied

papers

. It

is o

bvious that

acid

in

the pape

r

accelera

tes

the

degrad

ation of the

film

. Also

deacidification

appears to make

the

film

somewhat

more

stable.

D

ata on

th

e ef

fect of

w

ashing

and of

deacidific

a

tion

on

the

physical properties

of

paper

from

old

b

ooks are

given in table 13.

Specimens wer

e

de-

aci

dified in the usual

way,

an

d other

specimens

w

ere

treated

with

w

ater

instead of the

deacidifica

tion

solutions. Th

e

d

eacidification

pro

cess

did

not

cause

any

signif

icant change

in tensile strength

or

f

olding endurance.

TABLE

13

.

Pa

ges

from b

ook

dated

184 :

Deacidifled__

_._

__._____._

Pa ges

from book dated1869 :

Untreated

....

Washed

with

water...

....

Deac

idifled..

_ _ _

Te nsile strength

,

kg/15-mm

strip

2.9

2.6

2.9

3.9

3.7

3. 8

Cro w

1.9

1.7

2. 0

2.6

2.5

2. 4

Folding endurance,

MIT,

0.5-kg

tension,

dauble

folds

20

31

31

2

4

3

Croat

13

16

18

2

4

3

Although lamin

ation of archiva

l

do

cuments

with

cellulose

acetate

film

is

usually

accomplished

by

means of

heat

and

pressure, Kathp

alia hasd

e

scr

ibed a solv

ent lamina

tion technique

that does not

require

spec

ial

equip

ment [2 1].

A sandwic

h,

c

on

s

isting of tissue, film, doc

ument,

film, and

tissue is

asse

mbled on a flat

surfa

ce. Using ano

nlinting

cloth, a

cetone is appl

ied

to

the sand

wich i

n

th

e

centeran

d

w

iped toward t

he edges. The

sandwich

is

t

hen turne

d ov

er and

the

process repea

ted.

Be

st re

sults

a

reob

tained if the laminate

is

placed

in

a letter p

ress

or

hydraulicpr

ess for a few hours.

Gear

[22]

hascompared

some

physical

properties

of

laminates p

repared byt

he Kathpal

ia

method

with thoseof

laminates p

repared u

sing a

stea

m-

hea

tedflatb

ed p

ress.

These

data

are

reproduced

i

n

table 14.

It is

obvious t

hat

the

solvent tec

h

nique

compares

favorably

with the machine

method

using

h

eat and pr

essure. The

solvent

lam

ination techniqu

e s

hould be a

ttractive

to a

n

operator

who cannotjustify the

cost

of a

l

aminating

press.

15


22/28

TA B LE 14.

b

Direction

Pa

pe r

t

d

->

t

-

Film

f

t

tt

t

tt

t

-

Tensile

strength

So

l

vent

6.3

12 .7

Ma

chine

6.8

12.1

2.7

1.9

2.0

1.5

2.1

Elonga

tion( )

So

l

vent

3.2

5.1

Ma

chine

3.7

3.7

2.2

3.5

14.0

28 .5

2

.3

Too weak

to

te

st

Edge tear 0)

Sol

vent

4

10

45 0

Ma

ch

ine

4

10

45 0

1 4

180

1,050

Specim

ens

not

ob

tained

T

oo weak

to

test

I

nternal

tear

Sol

vent

1 5

82

Ma

chine

64

88

26.8

29

.6

3.

0

3.0

12.0

Kat

hpalia me

thod

of

solvent lamination.

b

Steam-heated fla

tbed press;

same

con

ditions as

described jn s

ection 5.

Modified Finch

metho

d

d

Mach

ine direction.

Cross direction.

Acetone

is

som

ewhatto

xic, a

nd the

m

aximum

allowable c

oncentration

in the atm

osphere

is

ge

nerally

considered

to

be

about 500 volumes

of

acetone

vapor

per

million

volumes of

air

[23

].

Acetone

is

flammabl

e

and mixtures

of acetone

vap

or with air between

2.5

and 12.8

perce

nt,

are explo

sive [24]. Th

erefore

adequat

e

s

afety

precautio

ns

s

hould be

mainta

ined.

Another appro

ach which m

ay be u

seful

f

or

special purposes

is

lamination

of

a

non

woven

fabric, using an

adhesive,

to

on e side

of

the

document

.

Tribolet [25] has sugg

ested

this

tec

hnique for

mounti

ng

docum

ents

for display

purposes

and to add

strength where

only

limit

ed

reinforceme

nt is requi

red. This shoul

d

addsuffi

ci

ent

streng

th

to allow

care

ful ha

ndling,

and the

docu

ment wou

ld

stil

l be availa

ble

to

be

seen

and

to

uched

in

its or

iginal state

. The stabili

ty

of

the adhesives

and

of

the

n

o

nwoven fabrics

is

a factor that would

have to

be cons

idered

in

the preservatio

n

of

documents

by th

is

tech

nique.

P

olyethylene

and polyethy

lene tere

phthalate

fil

ms

are

probably

the

only

films

other than

the

ce l

lulose

es

ter type whi

ch can

presently be

conside

red as po ssible

lamina

ting

film

s.

Po

lyethylene

appears promi

sing, especi

ally some

of

the ne wer typ

es ofpolyeth

ylene

and a chem

ically

sim

ilar polymer,

polypropy

lene.

This

g

roup

of po

lymers merits fu

rther

study. The

load-

elo

ngation data in tabl

e 4 a

nd

figur

e 2

2

sh

ow some

ob

vious adva

ntages and disad

vantages.

The yield

strengt

h

is

very low,a

nd the

strength at 2 - to3-

percent elongation,

which

is

the value

that

is

im-

100

ELONGATION,

150

FIGU

RE 22.

po

rtant in protec

tion of the

pap

er, is still low

er.

This

is probably

s

ufficient for

ordin

ary

servi

ce, but

a

much

milder

impact

wo

uld

be

suffi

cient to dam

age

the lamina

te

tha

n

on

e pr

epared

with

cellulose

a

cetate. The edge

tear of polye

thylene film

is

compar

able to th

at of cellulose

acetate

film.

Polyethylen

e terephtha

late has the

best

ph

ysical

properties fo

r archival purposes

of

any film studied

.

Ho

wever,

th

e

selec

tion of an adhesive

with go

od

aging

qualities

for

use

with

it would

require

fur

ther

work.

The load-elongation

data

in

table

4

and

fig ure

22

show th

at a 0.5-mil

polyethyle

ne tereph

tbalate

film

is very

similar i

n behavio

r to 1.0 -mil cellul

ose

acetat

e

fi

lm

up

to the yi

eld point. These

two films

havesimilar c

apacities

to protect

the body

of

a

docume

nt. Po

lyethylene

terephthalate

ha

s a

mu

ch highe

r

energ

y to

rupture and a highe

r meas

ure

d ed g

e tear.

T

herefore,

the edge

tear in serv

ice should

be ve

ry satisfactory. It

could be us

ed

in

thinner film

s

to

equal

the

perform

ance

of cel

lulose

a

cetate

p

lus tissue,or in

thickerfilms

to sub

stitutefo

r

cloth

reinforcemen

t.

A problem

with film

s such asp

olyethylene

and

poly

ethylene

terepbthalate

is the diffic

ulty of re

moval from

a

document, should this

be come nec

essary.

Neith

er

f

ilm

is soluble a

t

room

tem

pera

ture in

a

ny

known solv

ent. Althoug

h remov

al is

possible, the

proba

bility

of d

amage to

the docu

ment

is much

greater than

wi

thcellulose

acetate.

One

approach that would

make

for easier rem

oval

is the use

of anonwoven

fabr

ic

with an

adhesi

ve,

as

discussed

in

sectio

n 7.

A

nonw

oven

fabric

madefrom

polyethylene

terephth

alate fiber

w

ould

a

dd

considerable

st

rength toa doc

ument with

little

in

crease

in

thickness,

assuming

that tb

e proper


23/28

adhesive

were

avai

lable. The open texture

of the

non

woven fabric would allow access

of

a

solvent to

th

e

adhesive,

if removal

of the fabric became

necessary.

Th

ree

N

BS

directori

es

laminated

with pol

y

ethyle

ne terephthalate, polyethylene,

and

cellul

ose

acetat

e

films

showedno significant

differences in

thei

r

con

ditions after abo

ut 6 months

of use.

The basic elements necessary for

a

performance

specificati

on and

for

a composition specification

are

given in tables 15 a

nd 16. It

should

be

noted

that

the

accelerat

ed aging test

will

require several

weeksfor completion.

Therefore the

establish

me

nt

o

f a list

of

acceptable

materials under com

mercial

designations, with

tests of representative

lots at intervals

rather than

the

testing of

each

procurement lot,

may

be requ

ired.

TABLE

15.

Tensile strength

at

break,

kilogram

s per

15-mm

width,

mini

mum...

Te nsile strength

at yield

poi

nt, kilograms per 15-mm

width,

mini

mum ______

_

F

olding

endurance,

MIT machine at 1- kg

te

nsion, double

Thickness __ _ __ _ _ _

_

_ _ _ _

_______mi l__

Heat

softening

temperature:

Moelter-Schweizer- _ _ __ .. ,

__C,_

A

ccelerated

ag

ing

for 40

days

hi mo

ist oxygen at 124 C

Rate

of change

of

intrinsic fluidity with time in days,,

maximum

_ _ _ _

, _ _ __... _ _ _ _ _ _ _

Time

to reach an intrinsic fluidity

of

1.0,

minimum..days.

V

iscosity

of cellul

ose

ac

etate, centipoises,

minimum:

Cast

film

______________________________.____

..

Extruded film...... .

. _ _______

_ .

1.8

1.

8

16.0

3.5 0.5

1,000

0 .88 10

114.5

2 5

123.5 2 5

0.0

2

40

100

60

shall

be

deter

mined

by ASTM

method D 882-56T [26], Metho

d

A , with a

rate of motionof

the

cro

sshead of 2

in./min. Special careshall be taken

to ensure the

first-class condition of

the specimen cutter; a

special double-

edge

film

cutter is recommended.

The

yield

poin

t

shall

belocated as

indicated in

section

3.3 of this publica

tion. A

general

discus

sion of stress-

strain

ph

enomena is given in refe

r

en ces

[27]

and

[28].

shall be

determined by method

T 423 m-50

of the T

echnical

Associatio

n o

f

the

Pulp

and P

aper Industry, usingthe

MIT

m

achine

a

t 1-kg

tension.

NBS5 Preservation of Documents by Lamination

Documents

Transcript of NBS5 Preservation of Documents by Lamination