United States Patent 1 1 9 1 .

1 1 1 1 3,9 67,9 9 8
Kane [ 4 5 ] J u l y 6, 1 9 76
[ 5 4 ] POLYETHYLENE 2,9 61 ,365 l l /1 9 6O Sl o o g . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 61 /232 x
TEREPHTHALATE/PAPERBOARD 1 2; same at al - -~ , , a ersso n . . . . . . . . . . . . . . . . . . . . . .
LAMINATE ANDMETHODOFMAKINGIT 3,61 9 ,21 5 1 1 /1 9 71 Bard . . . . . . . . . . . . . . . . . . . 229 /87 FX
CONTAINERBLANK FORMEDFRQM 3,71 6,369 2/1 9 73 Peu l man . . . . . . . . . . . . . . . . . . 4 26/4 1 2 x
SUCH LAMINATE ANDCONTAINER 3. 73735 4 6/!9 73 Hatto ri . . . . . . . . . . . . . . . . . . . . . 1 5 6/24 4 X
FORMEDFROMSUCH BLANK, AND 3,75 0,873 8/1 9 73 Ro man . . . . . . . . . . . 229 /35 MFx
$75 6,4 9 5 9 /l 9 73 BBmISS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229 /1 4 BL
CONTAINER 1 301 21 5 1 01 9 PATENTS ORAPPLICATIONS
[ 75 ] l nv ento r: W il l iamPau l Kane, Bo n Air, V a. 781 ,4 24 3/1 9 68 Canada
[ 73] Assig nee: E. l . Du Po nt de Nemo u rs and M1 9 304 7/1 9 68 United King do m
Co mpany , W il ming to n, Del . _ _
_ Primary ExaminerW 1 l l 1 amA. Po wel l
[ 22] F l ed: May 9 1 9 74 Assistant ExaminerDav id A. Simmo ns
[ 21 ] Appl . No . : 4 68,5 36
Rel ated U. S. Appl ic atio n Data [ 5 7] ABSTRACT
[ 62] Div isio n o f Ser. No . 28l 9 4 3. Au g . I8, 1 9 72, Pat. No . Ac o ntainer is pro v ided f o rmed f ro ma bl ank made o f
3324 01 3- a l aminate wh ic h inc l u des no nbro wning paperbo ard
and at l east an inner l ay er o f su bstantial l y amo rph o u s
[ 5 2] U. S. Cl . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 5 6/226;_ 1 5 6/24 4 ; po l y eth y l ene tereph th al ate bo nded to th e paperbo ard
q 1 5 6/ 322 4 28/4 81 4 28/5 1 4 by its o wn su bstanc e. Ameth o d o f making th is l ami
[ Sl ] Il l . Cl . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . nate is pro v ided inc l u ding th e steps o f h eating an u n_
[ 5 8] h el d o f Searc h " " " " " " " " ] 5 _ 6/24 4 332 4 9 9 82: c o ated su rf ac e o r bo th su rf ac es o f th e paperbo ard to a
5 6/322 226 227 61 /232 25 0 25 1 : temperatu re o f at l east abo u t 285 F. and extru ding th e
229 /31 7 3' 5 R 1 4 BL 31 R 87 4 8 T po l y eth y l ene tereph th al ate l ay er o nto th is su rf ac e o r
4 26/4 1 24 1 5 ; 1 1 7/] 5 5 UA 61 K 9 3/36 th ese su rf ac es. Ameth o d o f c o o king is pro v ided in
MM 36 PC 36 M c l u ding th e steps o f f o rming a c o ntainer f ro mth e
, bl ank, pl ac ing f o o d in th e c o ntainer and c o o king th e
[ 5 6] Ref erenc es C' ted f o o d at a temperatu re o f u p to abo u t 4 00 F.
UNITEDSTATES PATENTS ' .
2,4 65 ,31 9 3/1 9 4 9 W h in?el d et al . . . . . . . . . . . . . . . 1 61 /4 02 x 8 Cl a' ms 6 Drawmg F g u ' es
US. Patent J u l y 6, 1 9 76 Sh eet 1 o f 2 3,9 67,9 9 8
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U. S. Patent J u l y 6, 1 9 76 Sh eet 2 o f 2 3,9 67,9 9 8
3,9 67,9 9 8
1
POLYETHYLENE " - '
TEREPHTHALATE/PAPERBOARDLAMINATE
ANDMETHODOFMAKINGIT, CONTAINER
BLANK FORMEDFROMSUCH LAMINATE AND
CONTAINERFORMEDFROMSUCH BLANK, AND
COOKINGMETHODUSINGSUCH CONTAINER
Th is is a div isio n o f appl ic atio n Ser. No . 281 ,9 4 3,
?l ed Au g . 1 8, 1 9 72(no w U. S. Pat. No . 3,9 24 ,01 3.
BACKGROUNDo r THE mv ermo u
1 . Fiel d o f th e Inv entio n ' > -
Th is inv entio n is a c o o king meth o d u sing a no v el
c o ntainer' f o rmed f ro ma bl ank o f a no v el material (i. e. ,
a l aminate o f at l east a l ay er o f po l y eth y l ene tereph th al
ate and no nbro wning paperbo ard) . Th is inv entio nis
al so a meth o d o f making th is no v el l aminate inc l u ding
th e step o f h eating , at c ritic al temperatu res, an u n
c o ated su rf ac e o r su rf ac es o f th e paperbo ardv to im
pro v e adh esio n between it and th e po l y eth y l ene tere
ph th al ate material extru ded th ereo n.
2. Desc riptio n o f th e Prio r Art >
Th e f o l l o wing prio r art is o f interest to th e l aminate
and its meth o d o f manu f ac tu re o f th is inv entio n:
U. S. Pat. No . 3,4 02,086 to Smith et al . sh o ws apro
c ess f o r h o t-mel t extru sio n c o ating o f paperbo ard o r
paper with a rando mc o po l y mer o f eth y l ene-c o ntaining
a,B-eth y l enic al l y u nsatu rated mo no c arbo xy l ic ac id
wh erein th e paper is preh eated by h o t ro l l s to a temper
atu re with in th e rang e o f 80 to 25 0 C. prio r to being
mel t c o ated. . . > I ,
U. S. Pat. No . 3,4 9 8,865 to Paq u in et al . sh o ws a
c o ntinu o u s pro c ess f o r c o ating paper with a ?l mo f
extru dabl e pl astic , su c h as po l y eth y l ene, wh erein th e
air in th e reg io n o f c o nv erg enc e o f paper and pl astic
?l mis io niz ed. Th e spec i?c atio n disc l o ses th at th e
paper wh ic h c o ntac ts th e mo l ten po l y eth y l ene is h eated
by u se o f steam-h eated ro l l s to a temperatu reo f 65 to
1 1 5 C. l nf rared o r o th er h eating el ements may al so be
u sed f o r h eating th epaper. - ' > . ,
Canadian Patent No . 5 29 ,361 to Fiel ds sh o ws v apro
c ess f o r extru sio n c o ating a sy nth etic l inear po l y mer
h av ing a sh arp mel ting po int o nto a sh eet. Po l y esters
are disc l o sed as u seabl e material s f o r th e c o ating and
paper is inc l u ded as a material th atc an be u sed f o r th e
sh eet. . . . v -, > 1
Canadian Patent No . 781 ,4 24 to Marsh al l disc l o ses a
meth o d o f c o ating a po ro u s web with a c o ntinu o u s?l m
o f a th ermo pl astic po l y mer wh erein th e po ro u s web is
preh eated bef o re th e appl ic atio n o f th e mo l ten ?l mo f
th e po l y meric material . Po ro u s papermay be u sed as
th e po ro u s web material and po l y esters may be u sed f o r
c o ating th e po ro u s webs. , > ' -
British Patent No . 1 ,1 1 9 ,804 to Ro h m&,Haas Co m
pany disc l o ses a l aminate c o mprising a su bstrate su c h
as a sh eet o f paper and a l ay er o f po l y h exameth y l ene
tereph th al ate wh ic h h as been mel t-extru ded th ereo n.
. Aprio r art patent o f interest to . th e c o ntainer and
c o o king meth o d o f th is v inv entio n is U. S. Pat. No .
3,276,9 00 to Fu nc k, wh ic h sh o ws th e u se o f a paper
bo ard c o mpo nentina c o ntainer u sed in c o o king f o o ds
at rel ativ el y h ig h temperatu res. .
Ano th er patent o f interest in th e f o o d c o ntainer art is
U. s. Pat. No . 3,31 6,1 02 to Do l l -eta] . - wh ic h sh o ws a
f o o d tray bl ank, c o ntainer and pac kag e, and v wh ic h
bl ank inc l u des meansf o r l o c king parts o f th e c o ntainer
to g eth er to h o l d it in erec ted po sitio n . with o u t u se o f
adh esiv es o r mec h anic al f asteners.
5
1 0
20
25
30
35
4 0,
4 5
5 0
5 5
. 2
- U. S. Pat. No . 3,5 5 0,835 to Persso n is al so exempl ary
o f th e c o ntainer and c o o king arts. Su c h patent teac h es
a pac kag e espec ial l y f o r f o o d pro du c ts, wh ic h pac kag e
is a tray erec ted f ro m a paperbo ard bl ank wh ic h h as at
l east o ne side a ?u id-tig h t pl astic c o ating , i. e. , po l y pro
py l ene, wh ic h is adapted to be seal ed and with stands
h eating to abo u t 305 F. W h il e th is pac kag e is su itabl e
f o r rel ativ el y l o w c o o king temperatu re u se, it c anno t
with stand h eating at th e h ig h temperatu res abo v e
325 F. and to abo u t 4 00 F. , wh ic h temperatu res are
th o se mo st c o mmo nl y u sed in th e prec o o ked, c o nv e
nienc e f o o d areas o f c o o king .
SUMMARY OF_ THE INV ENTION
Ac c o rding to th e present inv entio n, a c o ntainer is
pro v ided f o r u se, pref erabl y , in th e pac kag ing o f f o o d
and f o r u se in th e su bseq u ent c o o king o r reh eating o f
th e f o o d in preparatio n f o r h u man c o nsu mptio n. Th e
c o ntainer is f o rmed f ro ma bl ank made' o f al material
c o mprising no nbro wning paperbo ard with po l y eth y
l ene tereph th al ate material extru ded o nto o ne o r bo th
o f its su rf ac es. Th e meth o d o f making su c h material in
wh ic h an u nc o ated su rf ac e o r su rf ac es o f th e paper
bo ard is h eated, pref erabl y by ?ame, enabl es a bo nd to
be set u p between th e paperbo ard and po l y eth y l ene
tereph th al ate th at is e?' ec tiv e in u se appl ic atio n o f th is
so rt. l n f o rming th e c o ntainer f ro mth e bl ank o f th is
inv entio n, th e po l y eth y l ene tereph th al ate su rf ac e, o r
parts o f it, may be bro u g h t into abu tting c o ntac t with
o th er parts o f th e po l y eth y l ene tereph th al ate su rf ac e o r
with parts o f th e paperbo ard su rf ac e and sec u red o r
h eat-seal ed to g eth er, o r th e c o ntainer may bef o rmed
by appro priatel y f o l ding th e bl ank o r by h eating th e
bl ank and die pressing it into c o ntainer f o nn. Fo o d is
th en pl ac ed in th e c o ntainer, wh ic h f o o d may th en be
reh eated o r h eated to temperatu res u p to abo u t 4 00 F.
with o u t h av ing bro wning pro bl ems with th e paper
bo ard and with o u t h av ing del aminatio n pro bl ems with '
th e l aminate.
Th is c o ntainer do es no t del eterio u sl y ef f ec t th e c o o k
ing o f th e. f o o d c o ntained th erein and may be f o rmed at
l o w h eat-seal ing temperatu res and c o o ked o r u sed at
h ig h c o o king temperatu res and stil l remain attrac tiv e in
appearanc e. ' v '
1 Co o king c o ntainers are wel l kno wn to th e art. Many
ty pes o f material s are u sed to f abric ate th ese c o ntain
ers. Su c h material s c an g eneral l y be c h arac teriz ed into
o ne o f th reeprimary ty pes o r c o mbinatio ns o f th em.
Th ese ty pes are paperbo ard-al u minu mand c ertain
th ermo pl astic material s. Th ere are adv antag es and
disadv antag es resu l ting f ro mth e u se o f eac h o f th ese
ty pes o f material s in f abric ating f o o d c o ntainers. Fo r
exampl e, th e no npaperbo ard c o ntainers are g eneral l y
no nbio deg radabl e and th e al u minu mc o ntainers are
dif ?c u l t to h ermetic al l y seal and c anno t be u sed in
mic ro wav e o v ens; paperbo ard c o ntainers, o n th e o th er
h and, do no t h av e th ese disadv antag es.
Despite th e widespread u se o f paperbo ard in th e
- pac kag ing indu stry , h o wev er, c ertain l imitatio ns in its
60
65
u til ity h av e l o ng been rec o g niz ed. Fo r exampl e, u n
c o ated paperbo ard pac kag es are weakened by mo istu re
and are no t imperv io u s to g rease and o il s and c h ar and
bro wn at h ig h c o o king temperatu res. Fu rth er, th is pa
perbo ard bro wning is stil l an impo rtant, u nso l v ed,
pro bl emf ac to r ev en wh en th e paperbo ard is c o ated
with c ertain pl astic material s; i. e. , po l y pro py l ene
c o ated paperbo ard bro wns wh en h eated to tempera
tu res o f abo u t 305 9 1 : . Co nseq u entl y , wh en pac kag ing
3,9 67,9 9 8
c ertain ty pes o f f o o ds . f o r1 c o o king , paperbo ard may
l ac k a key pro perty rel ating to th eappearanc e o f th e
pac kag e. Oth er ph y sic al c h arac teristic s o f paperbo ard
h av e' l imited th e f o rms o f th e pac kag e and th e ty pes o f
su rf ac e treatment wh ic h c o u l d be u sed o n paperbo ard
pac kag ing material s. - , , i . . - . 1
Co nv enienc e f o o ds, f o r. exampl e, may be prec o o ked
and pac kag ed in c ertain c o ntainers and th en, reh eated.
Fo r th is reaso n th ey mu st be c apabl e o f with standing
th is su bseq u ent' f o o d-h eating o peratio n with o u tc au sing
adv erse ef f ec ts with th e f o o d o r th e pac kag e. Th e c o n
tainers u sed f o r th is sh o u l d be c apabl eo f being su b
j ec ted to temperatu res o f u p to 4 00 F. Prio r to th is
inv entio n, kno wn paperbo ard' c o ntainers c o u l d no t be
so empl o y ed primaril y bec au se su c h c o ntainers easil y
c h ar wh en su bj ec ted to temperatu res o f : th is o rder and
th e bro wning rdestro y st-th e. aesth etic s o f th e c o ntainer.
Th e. instant inv entio n. pro v ides . . no v el c o ntainers
f o rmed f ro ma bl ank made in part o f paperbo ard wh ic h
exh ibits u niq u e pac kag ing v ersatil ity and wh ic h o v er
c o mes-disadv antag es, su c h as bro wning at h ig h temper
atu res, o f c u rrentl y u sed c o ntainer material s. In ,its
bro adest terms, th is inv entio n is a dispo sabl e c o ntainer
wh ic h c o mprises' a l ay er o f no nbro wning paperbo ard
and at l easta l ay er o f . su bstantial l y amo rph o u s po l y eth
y l ene tereph th al ate bo nded to th e paperbo ard l ay er by
its o wn su bstanc e. Th is inc l u des, f o r exampl e- c o ntain;
' ers f o rmed f ro mbl anks by f o l ding , die-pressed c o ntain
ers and th e l ike. _ > ' . I Y
. Spec i?c al l y , th e instant inv entio n in o ne embo diment
pro v ides a c o ntainer f o r baking and c o o king wh ic h
c o mprises: ' _ r I ~ . ~ '
@ a' su bstantial l y ?at bo tto mpart; i
at l eastf o u r u pstanding sides h ing edl y c o nnec ted to
' th e' f l at bo tto m; ' v - 1 v '
" c o rners j o ining adj ac ent u pstanding sides h ing edl y
c o nnec ted to th e ?at bo tto mparts; ~ '
' th e c o ntainer being f o rmed o f a 2-pl y l aminate c o m
prising a l ay er o f no nbro wning paperbo ard and at
l east a l ay er o f su bstantial l y . amo rph o u s po l y eth y
l ene tereph th al ate bo nded to th e paperbo ard l ay er
by its o wn su bstanc e; and - , ' - v "
th e c o rners being f o rmed by h eat-seal ing - su rf ac e
po rtio ns o f th e su bstantial l y amo rph o u s po l y eth y
l ene tereph th al ate l ay er- o f adj ac ent sides to g eth er
' and th e po l y eth y l ene tereph th al ate. in th e c o mers
being partial l y c ry stal l ine, th ereaf ter. } ' j j .
l n ano th er embo diment, th is inv entio n' is a c o ntainer
f o r baking and c o o king wh ic h c o mprises: a su bstantial l y ?at bo tto mpart and bo dy parts c o m
nec ted th ereto ; ' - ' j , v i ' = th e c o ntainer being f o rmed o f a l aminate c o mprising
a l ay er o f no nbro wning paperbo ard and at l east a
' a l ay er o f su bstantial l y amo rph o u s po l y eth y l ene- tere
- ph th al ate bo nded to th e paperbo ard l ay er by its: I
' o wn su bstanc e; and
th e c o ntainer h av ing abu tting su rf ac e po rtio ns o f th e"
bo dy parts sec u red to g eth er. 1 ' * ' ~ .
In th is c o ntainer at l east o ne and, if desired, bo th ,-o f
eac h o f th e abu tting su rf ac e po rtio ns o f th e bo dy parts
is o f th e po l y eth y l ene tereph th al ate l ay er and; su c h
abu tting su rf ac e- po rtio ns may be h eat-seal ed to g eth er
o r sec u red to g eth er by -o th er meansj su c h ' a' s' stapl es o r
adh esiv es, o r by interl o c king parts, f o r exampl e. '
Al l o f th ese c o ntainers may be f o rmed f ro ma- c o n
bro wning paperbo ard h av ing a l east an extru ded l ay er
o f po l y eth y l ene;tereph th al ate bo nded th ereto .
1 . 1 Ameth o d O?f o rr' ning -a c o ntainerf ro rri-th is bl ank
inc l u des th e steps, o f : f o l ding th e bl ank wh ereby su rf ac e
po rtio ns. o f bo dy . partsl are bro u g h t -into abu tting
c o ntac tawith eac h o th ery -al l o f su c h su rf ac e po rtio ns
being o f po l y eth y l ene tereph th al ate; and h eat-seal ing
su c h abu tting su rf ac e . po rtio ns to g eth er to f o rma c o n
tainer. v Su c h abu tting -su rf ac e po rtio ns are h eat-seal ed
to g eth erh at a temperatu re o f at l east abo u t 3_ 20 F.
Ano th er meth o d o f f o rming " a c o ntainer' f ro mth e
bl ank inc l u des th e steps o f : f o l ding th e bl ank wh ereby
su rf ac e po rtio ns o f th e bo dy parts are bro u g h t into
abu tting -c o ntac twith eac h o th er; and sec u ring su c h
abu tting su rf ac e po rtio ns' rto g eth er to f o rm a c o ntainer.
Su c h abu tting : su rf ac e po rtio nsq may be h eat-seal ed
~ to g eth er at a temperatu re o f at l east abo u t 320 F. o r
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5 0
60
65
tainer bl ank o f th is inv e nt io nh av ing parts inc l u ding -a I
bo tto mpart with bo dy parts c o nnec ted, th ereto ,_ j 1 su c h
bl ank being f o rmed o f a l aminate inc l u ding a no n
sec u red to g eth er' by o th er means. At l east o ne o f eac h
. o f su c h abu tting ' su rf ac e po rtio nsiis o f th e po l y eth y l ene
tereph th al atel ay er and th e o th er o f eac h o f su c h abu t
ting su rf ac e po rtio ns may be o f th e no nbro wning paper
bo ard. ' -
Stil l ano th er meth o d o f f o rming a c o ntainer f ro mth e
bl ank inc l u des th e steps o f : h eating th e bl ank to a tem
peratu re o f at l east1 320 F. ; and pressing -th e bl ank to
f o rma c o ntainer. . - . > - ' -' '
And, f u rth er, a meth o d-: o f th is inv entio n is pro v ided
o f making a l aminate su itabl e f o r u se in making th ese
bl anks andf c o ntainers' i' c o mprising th e steps o f wh ic h
inc l u dev passing ' ano nbro wning paperbo ard web h av ing
a pH o f between 7. 0 and 7. 5 adj ac ent a h eating . so u rc e;
h eating an u nc o ated ?rst su rf ac e v o f th e paperbo ard to
a temperatu re o f at l east abo u t285 F. by means o f th e
h eating -so u rc e; extru ding a l ay er o f po l y eth y l ene tere
ph th al ate. o nto th e u nc o ated ?rst su rf ac e o f th e h eated
paperbo ard,su c h po l y eth y l ene tereph th al ate h av ing an
intrinsic v isc o sity with in th e rang e o f 0. 5 1 to 0. 85 ; and
c o o l ing th e extru ded-l ay er o f po l y eth y l ene tereph th al ;
ate to so l idif y it> andto ef f ec t a bo nd between th e pa
perbo ard and th e po l y eth y l ene tereph th al ate to f o rma
2-pl y ' l aminate : - ' Y ~ * Av meth o d o f th isf inv entio n f u rth er is pro v ided o f
making a 3- pl y Il aminate su itabl e f o r th ese-same u ses
wh erein" th e' o th er su rf ac e o f th e paperbo ard' o f th e
2-pl y l aminate al so is u nc o ated and wh erein th e paper
bo ard is h eaed to a temperatu re o f f ro mabo u t 285 F.
to abo u t 34 0 F. inc l u ding th e additio nal ' steps o f : ex
tru ding a l ay er o f po l y eth y l ene tereph th al ate o nto su c h
u nc o ated sec o ndi-isu rf ac e o f th e ' h eated paperbo ard,
su c h l po l y eth y l ene tereph th al ate Ih av ing an" intrinsic
v isc o sity with in' l th e' rang e o f 0. 5 1 to 0. 85 ; and c o o l ing
th is extru ded l ay er o f po l y eth y l ene tereph th al ate to
so l idif y it and to ef f ec t a bo nd' betweeri it and th e pa
perbo arditb f o rm- th e 3-pl y l l aminate. ' V = ' '
And; l astl y , a meth o d is pro v ided f o r c o o king in th ese
no v el -c o ntainersf o rmedf ro mbl anks made o f th ese
no v el 2-pl y and 3- pl y l aminates, wh ic h c o o king meth o d
inc l u des th e steps o f rf o i' ming a c o ntainer f ro ma bl ank
f o rmed f ro m" a 2-pl y l aminate c o nsisting o f a no n
bro wning paperbo ard l ay er h av ing a l ay er o f po l y eth y - .
l ene tereph th al ate extru ded th ereo n" and bo nded
th ereto by its o wn su bstanc e by th e meth o ds prev io u sl y
desc ribedrpl ac ing ' f o o d inl th eic o ntain' er; and, c o o king
th e f o o d at a-temperatu re io f ' u p -to abo u t 4 00 F.
, v i . ,iu i~ : i= . DESc ' RirTio N o rrnno l iAwmo 7
FIG. 1 ' is aidiag rarnm' atic v iew o f apparatu s su itabl e '
f o r making a 2-pl y and ' 3= pl y l aminate o f th is inv entio n;
3,9 67,9 9 8
5
FIG. 2 is a f rag mentary pl an v iew o f a c o rner bl ank
made f ro ma l aminate o f th is inv entio n (with parts
o mitted f o r c l arity ) ; and '
FIG. 3 is a perspec tiv e v iew sh o wing a c o ntaine
f o rmed f ro mth e bl ank o f FIG. 2. t v
FIGS. 4 and 5 are perspec tiv e v iews' o f ano th er c o n
tainer o f th is inv entio n. sh o wing a l o c king tab bo dy part
bef o re and af ter it is tu c ked into po sitio n to embrac e
and retain f o l ded side extensio n bo dy parts in pl ac e.
FIG. 6 is a perspec tiv e v iew sh o wing stil l ano th er
c o ntainer o f th is inv entio n (i. e. , a c o o king pl ate) wh ic h
may be f o rmed by die pressing a su itabl e bl ank made
f ro ma l aminate al so o f th is inv ento n. '
DESCRIPTION OFTHE PREFERRED
EMBODIMENTS
Ref erring to th e drawing s, and in partic u l ar FIG. 3,
th ere is sh o wn a ty pic al no v el c o ntainer C o f th is inv en
tro n.
Su c h c o ntainer C is f o rmed' f ro ma bl ank B, o f th e
ty pe sh o wn in FIG. 2, wh ic h bl ank is su itabl y c u t and
sc o red to de?ne parts inc l u ding a bo tto mpart 1 0 with
bo dy parts o r sides 1 1 h ing edl y c o nnec ted th ereto
al o ng f o l d o r sc o re l ines 1 2. Oth er f o l d l ines, su c h as
th o se desig nated 1 3, extend f ro mth e f o l d l ines 1 2 and
de?ne means f o r enabl ing th e bl ank to be f o l ded at th e
c o mers 1 4 th ereo f in f o rming th e c o ntainer C, in a
manner to be desc ribed.
In f o rming th e c o ntainer C f ro mth e bl ank Bth e sides
1 ] are f o l ded u pwardl y with respec t to th e bo tto mpart
1 0 and c o mer po rtio ns 1 4 o f th e inner su rf ac e o f adj a
c ent sides' 1 1 are bro u g h t into abu tting c o ntac t with
eac h o th er and sec u red (i. e. , h eat-seal ed) ' to g eth er to
f o rmth e c o rners 1 4 o f th e c o ntainer C f ro mth e c o mer
po rtio ns ' 1 4 . Th e material o f th e inner su rf ac e o f th e
bl ank Bis su c h th at it is h eat-seal abl e to itsel f o r to
paperbo ard l ay er 1 5 as wil l be f u rth er expl ained. '
Th e bl ank Bis made f ro ma no v el l aminate o f th is
inv entio n c o nsisting o f a l ay er o f no nbro wning paper
bo ard 1 5 , su c h as so -c al l ed 1 4 po int bo ar , h av ing a
l ay er o f po l y eth y l ene tereph th al ate l 6 extru ded o nto
an u nc o ated ?rst su rf ac e o r su c h paperbo ard 1 5 in a
no v el manner and bo nded to su c h paperbo ard by its
o wn su bstanc e to f o rma 2-pl y l aminate 1 7, as best
sh o wn in FIGS. 1 and 3. If desired, ano th er' l ay er o f
po l y eth y l ene tereph th al ate 1 6' may be extru ded o nto
th e o th er u nc o ated sec o nd su rf ac e in ac c o rdanc e with
th is inv entio n to f o rma 3-pl y l aminate 1 7 . '
Oth er ty pic al c o ntainers C and C f o rmed f ro mth e
2-pl y and 3-pl y l aminates 1 7 and 1 7 o f th e inv entio n
are sh o wn in FIGS. 4 -6.
Th e c o ntainer C is f o rmed f ro ma su itabl y c u t and
sc o red bl ank, as sh o wn, f o r exampl e, in US Pat. No .
2,373,730, wh ic h bl ank inc l u des a bo tto mpart 1 0 and
bo dy parts 1 1 c o nnec ted th ereto by f o l ding th e bl ank
wh ereby su rf ac e po rtio ns o f th e bo dy parts 1 1 are
bro u g h t into c o ntac t with eac h o th er and sec u red to
g eth er (i. e. , h eat-seal ed o r interl o c ked, etc . ) to f o rm
th e c o ntainer. In o th er wo rds, in f o rming th e c o ntainer
C; th e l o c king tab' bo dy parts' l 8 is tu c ked into th e
po sitio n sh o wn in FIG. 5 to embrac e and retain th e
f o l ded side extensio n bo dy parts 1 9 in pl ac e, wh ic h
tu c king sec u res th e su rf ac e po rtio ns o f th e bo dy parts
to g eth er.
It is no ted th at in th is po sitio n su rf ac e po rtio ns o f th e
bo dy parts are bro u g h t into abu tting c o ntac t with eac h
o th er with parts o f th e po l y eth y l ene tereph th al ate l ay er
1 6 su rf ac e in c o ntac t with parts o f th e paperbo ard l ay er
20
25
35
4 5
5 5
60
65
1 5 su rf ac e. W h il e th e tu c king o f th e tab 1 8 into po si
tio n' abo v e wil l sec u re th e su rf ac e parts to g eth er, if
desired, th e parts may al so o r o nl y be h eat-seal ed to
g eth er to do th e same. Th is inv entio n, th en, inc l u des
th e h eat-seal ing o f su rf ac e po rtio ns o f th e po l y eth y l ene
tereph th al ate l ay er to o th er po rtio ns o f th at l ay er as
wel l as to th e paperbo ard l ay er and f u rth er inc l u des th e
interl o c king o f th ese parts to g eth er, in f o rming a c o n
tainer o f th is inv entio n.
Th e c o ntainer C" , as sh o wn in FIG. 6, is stil l ano th er
exampl e o f a c o ntainer f o rmed u sing a l aminate 1 7 o r
1 7 o f th is inv entio n, wh ic h c o ntainer (i. e. , a c o o king
pl ate) may be f o rmed f ro ma su itabl y sh aped bl ank by
h eating th e bl ank to at l east 320 F. , and by pressing th e
h eated bl ank to f o rma bo tto m1 0 with bo dy po rtio n
1 1 c o nnec ted th ereto .
Th e spec i?c ty pe o f paperbo ard 1 5 u sed in f o rming a
l aminate o f th is inv entio n is c ritic al . Amo ng its mo st
impo rtant c h arac teristic s is th at th e su rf ac e o f su c h
paperbo ard to wh ic h th e po l y eth y l ene tereph th al ate
l ay er is to be f u sed pref erabl y is u nc o ated and, if c o ated
at al l , sh o u l d no t be c l ay c o ated. It h as been f o u nd th at
u nl ess th is is so th e adh esio n pro perties are l ess th an
th o se desired. "
Oth er pro perties o f th e paperbo ard wh ic h are re
q u ired wh en it is c o mbined with a po l y eth y l ene tere
ph th al ate l ay er f o r u se in c o o king at h ig h temperatu res
inc l u de th e pro perty o f no nbro wning . It h as been f o u nd
to be c ritic al th at th e pH mu st be c o ntro l l ed between
7. 0 and 7. 5 to pro v ide a paperbo ard th at do es no t
bro wn at c o o king temperatu res o f u p to abo u t 4 00 F.
As to no nbro wning , it h as been f o u nd th at th e su rf ac e
o f th e paperbo ard o ppo site th at to wh ic h th e po l y eth y
l ene tereph th al ate l ay er is adh ered may be c o ated with
a c l ay c o ating , if desired, and th at it is stil l po ssibl e to
o btain exc el l ent adh esio n to th e no nc o ated side o f th is
paperbo ard. '
' Th e po l y eth y l ene tereph th al ate material o f th is in- _
v entio n is f o rmed f ro ma po l y mer f o rmed by th e c o n
densatio n reac tio n o f eth y l g l y c o l and tereph th al ic
ac id. Partic u l ars o f th is material are sh o wn and de
sc ribed in US. Pat. No . 2,4 65 ,31 9 to W h in?el d and
Dic kso n. Mo re spec i?c al l y , po l y eth y l ene tereph th al ate
u sef u l in preparing th e l aminate o f th is inv entio n in
c l u des (a) po l y mers wh erein at l east abo u t 9 7% o f th e
po l y mer c o ntains th e repeating eth y l ene tereph th al ate
u nits o f th e f o rmu l a:
0 0
with th e remainder being mino r amo u nts o f ester-f o rm
ing c o mpo nents, and (b) c o po l y mers o f eth y l ene tere
ph th al ate wh erein u p to abo u t 1 0 mo l e perc ent o f th e
c o po l y mer is prepared f ro mth e mo no mer u nits o f di
eth y l ene g l y c o l ; pro pane-1 ,3-dio l ; bu tane-1 ,4 -dio l ;
po l y tetrameth y l ene g l y c o l ; po l y eth y l ene g l y c o l ; po l y
pro py l ene g l y c o l ; 1 ,4 -h y dro xy meth y l c y c l o h exane and
th e l ike, su bstitu ted f o r th e g l y c o l mo iety in th e prepa
ratio n o f th e c o po l y mer and/o r iso ph th al ic ; bibenz o ic ;
naph th al ene 1 ,4 - o r 2,6_ -dic arbo xy l ic ; adipic ; sebac ic ;
d' ec ane-l ,l O-dic arbo xy l ic ac id, and th e l ike, su bstitu ted
f o r th e ac id mo iety in th e preparatio n o f th e c o po l y
mer.
3,9 67,9 9 8
7
Pref erabl y , th e intrinsic v isc o sity o f th e po l y meric
material o f th is inv entio n is between 0. 5 1 and 0. 85 .
Material s o f th is v isc o sity in ?ake f o rmmay be o b
tained as start-u p material s in th e f o rmo f c u t strands o r -
bead trimo r pel l etiz ed material o r ev en pel l etiz ed
?ake. Al l o f th ese ?akes are su bseq u entl y dried f o r a
perio d o f 2 h o u rs at 80 C. with 29 -inc h water u nder
v ac u u m. It h as been f o u nd th at bu l k densities o f 28-4 0
l bs. /f t. 3 h andl e wel l in sing l e sc rew extru sio n eq u ip
ment. .
Th e expressio n intrinsic v isc o sity is u sed h erein as
a measu re o f th e deg ree o f po l y meriz atio n o f th e po l y
ester and is de?ned as:
wh erein u r is th e v isc o sity o f a dil u te so l u tio n o f th e
po l y ester in a mixtu re o f 1 part tri?u o ro ac etic ac id and
3 parts meth y l ene c h l o ride, by v o l u me, div ided by th e
v isc o sity o f th e tri?u o ro ac etic ac id/meth y l ene c h l o ride
mixtu re per se measu red in th e same u nits at 25 C. and
v C is th e c o nc entratio n in g rams o f th e po l y ester per 1 00
c c . o f so l u tio n. Intrinsic v isc o sity is independent o f
c o nc entratio nby v irtu e o f th e extrapo l atio n to C = 0.
Po l y eth y l ene tereph th al ate h as an u nu su al nu mber o f
pro perties wh ic h enabl e it to serv e a div erse rang e o f
appl ic atio ns. Th ese bal anc ed pro perties enabl e it to be
partic u l arl y u sabl e as' a pac kag ing material f o r f o o d. As
an exampl e, po l y eth y l ene tereph th al ate do es no t g et
brittl e with ag e, it h as a l o ng sh el f l if e; it pro v ides a
permanent, no n-y el l o wing , dimensio nal l y stabl e base
and h as-exc el l ent resistanc e to g rease, o xy g en and
mo istu re. Fu rth er, it is resistant to initial tear and
sc ratc h ing and c an with stand h eav y impac t and pro
l o ng ed ?exing . Th ese and o th er pro perties are o f g reat
v al u e in pac kag ing appl ic atio ns.
Pref erabl y , th e th ic kness o f th e paperbo ard is abo u t
1 4 mil sand th e th ic kness o f th e po l y eth y l ene tere
ph th al ate l ay er is 1 mil o r th ereabo u ts. 4
In th e prac tic e o f th is inv entio n, it h as been f o u nd
nec essary to h eat an u nc o ated ?rst su rf ac e o f th e pa
perbo ard to a temperatu re o f at l east 285 F. bef o re th e
mo l ten po l y eth y l ene tereph th al ate material is extru ded
o nto th e paperbo ard. If th e sec o nd su rf ac e o f th e pa
perbo ard is c o ated, a maximu mtemperatu re o f 34 0 F.
h as been f o u nd po ssibl e. At temperatu res in exc ess o f
th is wh en c o ating o r extru ding po l y eth y l ene tereph th al
ate o nto th is u nc o ated sec o nd su rf ac e o f th e paper
bo ard, it h as been f o u nd th at bl o c king o c c u rs, primaril y
bl o c king o f th e c o ating o n th e ?rst su rf ac e to th e ex
tru ded material o r c o ating o n th e sec o nd su rf ac e o c
c u rs. Fu rth er, th e c o ating tends to adh ere to th e c h il l
ro l l at abo v e th is maximu m.
Abl ank f o rmed f ro mth e l aminates, eith er 2-pl y o r
3-pl y , o f th is inv entio n, h eat-seal s easil y at abo u t
320 F. Th is pro perty enabl es th e bl ank to be f o l ded, by
f o l ding th e bo dy parts al o ng th e f o l d l ines u pwardl y
with respec t to th e bo tto mpart and th e bring ing o f
su rf ac e po rtio ns o f th e bo dy parts to g eth er, su c h po r
tio ns al l being o f po l y eth y l ene tereph th al ate o r o ne
being o f paperbo ard and th e h eat-seal in g o f th ese po r
tio ns to g eth er to f o rmth e c o ntainer. Exc el l ent h eat
seal s o f po l y eth y l ene tereph th al ate to itsel f , f o r exam
pl e, may be o btained with densities o f 1 . 3300 to
1 . 3360, as measu red at 27 C. in CCh /h eptane so l id
mixtu re.
~ 1 5
20
25
30
4 0
4 5
5 0
5 5
60
65
8
Ty pic al h eat-seal ing temperatu res th at h av e been
f o u nd wo rkabl e in f o rming a c o ntainer o f th is inv entio n
h av e inc l u ded 320 F. at 3 sec o nds dwel l and 60 psi and
35 5 F. . at 3 sec o nds dwel l and 60 psi, eac h o f wh ic h
pro du c e a seal streng th (?ber tearing ) o f g reater th an
3,000 g rams/inc h wh en a l aminate o f 1 4 mil -th ic k pa
perbo ard c o ated with po l y eth y l ene tereph th al ate is
h eat-seal ed with abu tting su rf ac e po rtio ns o f th e po l y
eth y l ene tereph th al ate l ay er in c o ntac t with eac h o th er.
W h en th is l ay er is h eat-seal ed to an u nc o ated side o f
th e paperbo ard at 35 5 F. at 6 sec o nds dwel l and 60 psi
a seal streng th o f abo u t 600 g rams/inc h is o btained.
Th e c o ntainers o f th is inv entio n are partic u l arl y wel l
su ited f o r baking o r c o o king f o o ds at temperatu res u p
to abo u t 4 00 F.
Aty pic al meth o d o f c o o king inc l u des th e steps o f :
f o rming a c o ntainer f ro ma bl ank f o rmed f ro ma
l aminate inc l u ding th e no nbro wning paperbo ard
h av ing at l east a l ay er o f po l y eth y l ene tereph th al
ate extru ded th ereo n and bo nded th ereto by its
o wn su bstanc e by f o l ding th e bl ank to bring su rf ac e
po rtio ns o f th e po l y eth y l ene tereph th al ate l ay er
th ereo f into abu tting c o ntac t with o th er su rf ac e
po rtio ns o f su c h l ay er and by h eat-seal ing th ese
abu tting su rf ac e po rtio ns to g eth er; '
pl ac ing f o o d in th e c o ntainer; and
c o o king th e f o o d at a temperatu re o f u p to abo u t
4 00 F.
Ano th er meth o d o f c o o king inc l u des th e steps o f :
f o rming a c o ntainer f ro ma bl ank f o rmed o f a l ami
nate inc l u ding th e no nbro wning paperbo ard h av ing
at l east a l ay er o f po l y eth y l ene tereph th al ate ex
tru ded th ereo n and bo nded th ereto by its o wn su b
stanc e by f o l ding th e bl ank to bring su rf ac e po r~
tio ns o f th e po l y eth y l ene tereph th al ate l ay er
th ereo f into abu tting c o ntac t with su rf ac e po rtio ns
o f th e paperbo ard l ay er and by h eat-seal ing th ese
. abu tting su rf ac e po rtio ns to g eth er;
pl ac ing f o o d in th e c o ntainer; and
c o o king th e f o o d at a temperatu re o f u p to abo u t
4 00 F.
Stil l ano th er meth o d o f c o o king inc l u des th e steps o f :
f o rming a c o ntainer f ro ma bl ank f o rmed f ro ma
l aminate inc l u ding th e no nbro wning paperbo ard
h av ing at l east a l ay er o f po l y eth y l ene tereph th al
ate extru ded th ereo n and bo nded th ereto by its
o wn su bstanc e; pl ac ing f o o d in th e c o ntainer; and
c o o king th e f o o d at a temperatu re o f u p to abo u t
4 00 F. v Th is c o ntainer may be f o rmed by h eating
th e bl ank to at l east 320 F. and by pressing th e
h eated bl ank o r by f o l ding th e bl ank.
Lastl y , ano th er meth o d o f c o o king inc l u des th e steps
o f :
f o rming a c o ntainer f ro ma bl ank f o rmed f ro ma
l aminate c o nsisting o f th e no nbro wning paper
bo ard h av ing at l east a l ay er o f po l y eth y l ene tere
ph th al ate extru ded th ereo n and bo nded th ereto by
its o wn su bstanc e by f o l ding th e bl ank to bring
su rf ac e po rtio ns o f bo dy parts th ereo f into abu tting
c o ntac t with eac h o th er and by sec u ring th ese abu t
ting su rf ac e po rtio ns to g eth er; pl ac ing f o o d in th e
c o ntainer; and c o o king th e f o o d at a temperatu re
o f u p to abo u t 4 00 F.
In al l o f th ese c o o king meth o ds, th e no v el l aminates
o f th is inv entio n enabl e th e c o o king to be do ne u nder
wo rkabl e c o nditio ns and at u nu su al l y h ig h tempera
tu res, with o u t paperbo ard bro wning pro bl ems, f o r ex
ampl e.
3,9 67,9 9 8
9 . , .
ANDAPPARATUS FOR-MAKING
THE LAMINATE , ' . v .
Apref erred meth o d o f making th e l aminate' o f th is
inv entio n inc l u des th e step o f extru ding mo l ten po l y
eth y l ene tereph th al ate material o nto an. u nc o ated su r
f ac e o f paperbo ard material af ter su c h paperbo ard
material h as been ?ameh eated to atemperatu re o f at
l east 285 F. 1
Ref erring to FIG. I, th ere is sh o wn a sc h ematic rep
resentatio n o f an apparatu s f o r making th e material o f
th is inv entio n. Su c h material , wh eth er 2-pl y l aminate
1 7 o r a 3-pl y l aminate 1 7' is f o rmed u nder. no v el and
c ritic al c o nditio ns. - ' ' ~
In making su c h material , th e paperbo ard 1 5 , in th e
f o rmo f a web, f o r exampl e, is' su ppl ie' d f ro ma su ppl y
ro l l 21 and is mo v ed by appro priate means,. no t sh o wn,
past a h eating means o r so u rc e, su c h as ?ame o r_ h o t
g as, 22 and into a nip f o rmed by c o ntac ting ro tating
su rf ac es o f a nip ro l l 23 and a q u enc h o r' c h il l ro l l 24
wh ere th e paperbo ard is c o mbined with . a l ay er o f th e
f resh l y extru ded mo l ten po l y eth y l ene tereph th al ate
material 1 6 to f o rmth e 2-pl y l aminate l 7.
Th e mo l ten material 1 6 is extru ded o nto th e u n
c o ated su rf ac e o f th e paperbo ard l 5 -f ro man extru sio n
die 25 . Th is mo l ten material 1 6 desc ends th ro u g h an air
g ap u ntil it c o ntac ts th e ?rst su rf ac e o f th e paperbo ard
1 6 in th e nip area. Th e paperbo ard and po l y eth y l ene
tereph th al ate, l ay ers are ?rml y pressed to g eth er be
tween th e el asto meric c o v ered ro l l 23 and th e c h il l ro l l
24 so th at th e mo l ten po l y eth y l ene tereph th al ate l ay er
1 6 is j o ined to o r f u sed to th e paperbo ard 1 5 by its o wn
su bstanc e. ' Y - . . - .
It is impo rtant th at th e pressu re and. h eat appl ied are
su f f ic ient to c o mbine o r f u se th e paperbo ard and po l y
eth y l ene tereph th al ate l ay er to g eth er and it is c ritic al
th at th e ?rst u nc o ated su rf ac e o f th e paperbo ard be
h eated to a temperatu re o f at l east 285 F. prio r to ,th e
extru sio n o f th e po l y eth y l ene tereph th al ate l ay er o nto
su c h su rf ac e. . > w. ~
Th e l aminate 1 7 is th en passed by a sec o nd h eating
means 22' , aro u nd an idl er ro l l 26 and a nip ro l l 27 and
into a nip f o rmed by c o ac ting su rf ac es o f th e nip ro l l 27
and a q u enc h ro l l 28. Asec o nd mo l ten po l y eth y l ene
tereph th al ate l ay er 1 6 is c ast into th e nip f ro man
extru sio n die 29 and o nto th e u nc o ated sec o nd su rf ac e
o f th e h eated paperbo ard 1 5 wh ic h is c o ated with th e
mo l ten material s 1 6. Th e extru ded mo l ten po l y eth y
l ene tereph th al ate l ay er 1 6 l ike th e l ay er 1 6 prev io u sl y
appl ied sets u p stro ng l y and is f u sed to th e paperbo ard
member by its o wn su bstanc e to f o rmth e 3-pl y l ami
nate 1 7' .
Af ter f o nnatio n o f th e 3-pl y l aminate 1 7' , it is mo v ed
o nto a windu p 30 f o r f u rth er pro c essing o r u se.
Th e sec o nd su rf ac e o f th e paperbo ard 1 5 is h eated by
th e h eating means to a c ritic al temperatu re o f f ro mat
l east 285 F. to abo u t 34 0 F. Lo wer temperatu res th an
th is neg ate desired bo nding and h ig h er temperatu res
th an th is tend to c au se adh erenc e o f th e c o ating to c h il l
ro l l , f o r exampl e. ~
Spec i?c al l y , th e pref erred meth o d o f making th e
2-pl y l aminate 1 7 o f th is inv entio n inc l u des th e steps o f :
passing th e no nbro wning paperbo ard web 1 5 h av ing
an u nc o ated su rf ac e and a pH o f between 7. 0 and
7. 5 adj ac ent to a ?ame ty pe h eating means 22;
h eating th e u nc o ated ?rst su rf ac e o f th e paperbo ard
to a temperatu re o f f ro mat l east abo u t 285 F. to
abo u t 34 0 F. by u se o f th e ?ame;
METHODS OF
20
25
30
35
4 0
4 5
5 0
5 5
60
65
> 1 0
extru ding th e l ay er o f po l y eth y l ene tereph th al ate 1 6
,' [ o nto j th e u nc o ated su rf ac e o f th e h eated paper
bo ard 1 5 , su c h po l y eth y l ene tereph th al ate h av ing
~ , an ih trinsic ' v isc o sity with in th e rang e o f 0. 5 1 to
0. 85 ; and. i . >
c o o l ing th e extru ded l ay er o f po l y eth y l ene tere
( ph th al ate to so l idif y it and to ef f ec t a bo nd between
T th e paperbo ard l 5 and th e po l y eth y l ene tere
ph th al ate 1 6 to f o rmth e 2-pl y l aminate 1 7.
And, in making th e 3-pl y l aminate o f th is inv entio n
wh erein th e sec o nd su rf ac e o f th e paperbo ard al so is
u nc o ated and wh erein th e paperbo ard is h eated to a
temperatu re o f f ro mabo u t 285 F. to abo u t 34 0 F. ,
su c h meth o d inc l u des th e additio nal steps o f :
extru ding th e l ay er o f po l y eth y l ene tereph th al ate 1 6'
o nto su c h o th er u nc o ated su rf ac e o f th e h eated
paperbo ard 1 5 , su c h po l y eth y l ene tereph th al ate
v h av ing , an intrinsic v isc o sity . with in th e, rang e o f
0,5 ] to 0. 85 ; and _ , a ' _
v c o o l ing th is extru ded l ay er o f po l y eth y l ene tere
' . ph th al ate to so l idif y it and to ef f ec t a bo nd between
it and th e paperbo ard to f o rmth e 3-pl y l aminate
l 7. '
Th e pref erred meth o d o f h eating th e paperbo ard
su rf ac es is to c o ntinu o u sl y expo se th e su rf ac es o f th e
mo v ing paperbo ard to a ?ame su ppl ied by a g aseo u s
mixtu re o f pro pane and o xy g en o r pro pane and air. Th e
?ame wh ic h emerg es f ro ma su itabl e bu rner dev ic e is
c o mpo sed o f a primary env el o pe c o mprising th e l u mi
no u s, pal e bl u e, c o nic al inner po rtio n wh ic h is adj ac ent
to th e bu rner o ri?c e and th e sec o ndary env el o pe c o m
prising th e remainder? o f th e ?ame. W h en a rec tang u l ar
sh aped bu rner o ri?c e is empl o y ed th e primary env e
l o pe is wedg e-sh aped in c ro ss-sec tio n. Th e su rf ac e is
passed th ro u g h th e primary env el o pe o f th e ?ame at a
distanc e f ro mth e bu rner o ri?c e su f f ic ient f o r maintain
ing a sel f -su staining ?ame. Th e g aseo u s c o nstitu ents f o r
c o mbu stio n are pro pane and o xy g en o rair. Th e pro
po rtio ns o f th ese c o nstitu ents th at are su ppl ied to th e '
bu rner are no t c ritic al f o r_ _ th e su c c essf u l ?ame h eating
o f th e paperbo ard su rf ac e.
Th e o ne and two -side po l y eth y l ene tereph th al ate
c o ated paperbo ard l aminates o f th is inv entio n may be
u sed to c o nstru c t a v ariety o f f o o d c o ntainers su c h as
tray s, tray l ids, ro asting pans, and l iq u id-tig h t c o ntain
ers. Th e po l y eth y l ene tereph th al ate c o ating h eat~ seal s
wel l in additio n to h av ing exc el l ent barrier resistant
pro perties to g rease, water, and o xy g en. Th e h eat-seal
pro perty permits o ne to f o rml eak-pro o f l iq u id pac k
ag es and c o o king tray s and th e po l y eth y l ene tere
ph th al ate c o ating prev ents th e paperbo ard f ro mexc es
siv e bro wning ev en at o v en temperatu res o f u p to abo u t
4 00 F.
Fo r th e pu rpo se o f th is inv entio n, c o ntainer means
any pl ate, tray , f o l ding c arto n o r th e l ike th at is adapted
to h o l d an artic l e. It is f u rth er to be u ndersto o d th at al l
o f th ese c o ntainers may be pro v ided with a to p o r l id
wh ic h may be h eat-seal ed to an appro priate part o r
parts o f th e c o ntainer wh erein th e l o wer su rf ac e o f th e
to p is o f a po l y eth y l ene tereph th al ate material and is
bo nded to an inner o r u pper su rf ac e o r ?ang e o f th e
c o ntainers o f th is inv entio n, in wh ic h th e bl anks f ro m
wh ic h th ey are f o rmed are o f a po l y eth y l ene tereph
th al ate/paperbo ard l aminate o f th is inv entio n. Ty pic al
c o ntainers wh ic h may be so f o rmed are sh o wn in US.
Pat. No . 3, 5 5 0,835 to Persso n, US. Pat. No . 3,25 7,786
to Harriso n et al . , and US. Pat. No . 3,1 78,01 7 to Bo w
man, f o r exampl e.
3;9 67,9 9 8
' l l
l . Ameth o d o f f o rming a c o ntainer inc l u ding th e
steps o f : t ,
f o rming a bl ankf o rmed f ro ma-l aminate, inc l u ding
paperbo ard h av ing a l ay er o f su bstantial l y Yamo r- 5 tu l o f at l eastabo u t 320 1 3
ph o u s po l y eth y l ene tereph th al ate extru ded o nto an
u nc o ated su rf ac e th ereo f and wh erein su c h su rf ac e
' is h eated to a temperatu re o f at l east abo u t ~ 285 F.
prio r to ' su c h extru sio n; - '
f o l ding th e bl ank to bring su rf ac e po rtio ns o f th e
amo rph o u s po l y eth y l ene tereph th al ate l ay er
th ereo f into abu tting c o ntac t with o th er- su rf ac e
po rtio ns o f su c h l ay er and t " '
h eat-seal ing th ese abu tting su rf ac e po rtio ns to g eth er.
2. Ameth o d o f f o rming a c o ntainer inc l u ding th e
steps o f : I 7 _ " ' 7' ~ ' ' I' _
f o rming a bl ank f o rmed f ro ma l aminate inc l u ding
paperbo ard h av ing a l ay er o f su bstantial iy iarno r
ph o u s po l y eth y l ene tereph th al ate extru ded o nto an
u nc o ated su rf ac e th ereo f and wh erein su c h su rf ac e
, is h eated to a temperatu re o f at l east abo u t 285 F.
prio r to su c h extru sio n; '
f o l ding . th e bl ank to bring su rf ac e po rtio ns o f ' th e
amo rph o u s po l y eth y l ene ' tereph th al ate , l ay er
th ereo f into abu tting c o ntac t with po rtio ns o f th e
o th er su rf ac e o f th e paperbo ard and
h eat-seal ing th ese su rf ac e po rtio ns to g eth er.
3. _ Ameth o d o f f o rming a c o ntainer inc l u ding th e
steps o f : a _ - I
f o rming a bl ank inc l u ding a bo tto mpart with bo dy
' parts c o nnec ted th ereto , su c h bl ank being f o rmed
o f a l aminate inc l u ding paperbo ard h av ing at l east
an extru ded l ay er o f su bstantial l y amo rph o u s po l y
I eth y l ene tereph th al ate bo nded to a su rf ac e th ereo f 35
. and wh erein su c h su rf ac e is h eated. to a tempera-A
tu re o f at l east 285 F. prio r to su c h extru sio n; -
f o l ding th e bl ank wh ereby su rf ac e po rtio nso f bo dy
parts are bro u g h t into abu tting c o ntac t with eac h
o th er, al l o f su c h su rf ac e po rtio ns being o f po l y eth
y l ene tereph th al ate; and ' ~ I
1 0
20"
25
30
4 0
4 5
' 5 0
65
1 2
h eat-seal ing su c h abu tting su rf ac e po rtio ns to g eth er
to ' f o r ma c o ntainer_ . ' _ _ " _ I 1
4 . Th e meth o d o f c l aim3' wh erein su c h abu tting
su rf ac e po rtio ns are h eat-seal ed to g eth er at a tempera
( 5 ; Ameth o d, f f o rming a c o ntainer -, inc l u ding th e
stepso f r \ I I ; 1 . >
f o rming a bl ank inc l u ding -a bo tto mpart with bo dy
parts c o nnec ted th ereto , su c h bl ank being f o rmed
-o f a l aminate inc l u ding paperbo ard h av ing at l east
an extru ded l ay er o f su bstantial l y amo rph o u s-po l y
eth y l ene " tereph th al ate bo nded to a su rf ac e th ereo f
and wh erein su c h su rf ac e is h eated to a tempera
tu re o f at l east 285 F. ,by ?ame prio r to su c h extru
-_ sro n; ' . v . Y. ,Y . .
f o l ding th e bl ank wh ereby ; su rf ac ev po rtio ns o f th e
bo dy parts are bro u g h t into abu tting c o ntac t with
" eac h o th er; and*
' ~ sec u ring su c h abu tting su rf ac e po rtio ns to g eth er to
f o nn a c o ntainer . ' a Y: > . '
6. : Th e meth o d o f v c l aim5 wh erein su c h abu tting
su rf ac e po rtio ns are h eat-seal ed to g eth er at a tempera
tu re o f at l east abo u t 320 F. ' " w l
7. Th e meth o d o f c l aim6 wh erein at l east o ne o f eac h
o f su c h abu tting su rf ac e po rtio ns is o f th e po l y eth y l ene
tereph th al aterl ay er and th e o th er. o f eac h o f su c h abu t
ting su rf ac e po rtio ns is' o f th e' no n-bro wning paper
bo ard. a r v I -, ' > .
8. Ameth o d' o f f o rming a c o ntainer inc l u ding th e
stepso f : w i I. ; v . V 2
f o rming a bl ank inc l u ding a bo tto mpart with bo dy
1 parts c o nnec ted th ereto , su c h bl ank being f o rmed
o f a l aminate inc l u ding paperbo ard h av ing at l east
an extru ded l ay er o f su bstantial l y ? amo rph o u s po l y
eth y l ene tereph th al at' e bo nded to v a su rf ac e th ereo f
and wh erein su c h su rf ac e is h eated to a tempera
~ f tu re o f at l east 285 F. prio r to su c h extru sio n;
h eating th e bl ank to ' a temperatu re o f atil east 320 F. ,
> and l a - ' " > '
pressing th e bl ank to
~ * ~ .
f o rma c o ntainer.
* * * , = | =