CA2058882A1

CA2058882A1 - Formed paperboard containers and method of making same

Info

Publication number: CA2058882A1
Application number: CA 2058882
Authority: CA
Inventors: Douglas J. Renna
Original assignee: Douglas J. Renna; Network Graphics, Inc.
Current assignee: Network Graphics Inc
Priority date: 1991-02-28
Filing date: 1992-01-07
Publication date: 1992-08-29
Also published as: MX9200780A; EP0533860A4; EP0533860A1; WO1992015441A1; US5096650A

Abstract

ABSTRACT OF THE DISCLOSURE
A paperboard, containing a major portion of cellulose and a minor portion of an uncured biodegradable latex polymer, is molded into a shaped packaging form.

Description

2~8882 1 (SP~Cl~) D~cket; P-3168-1 ~ield o the Inv~ntioP

Tlle pre~ent invelltion relates to a Eormed paperboar product al-~, in particula~, to a procegs for preparing forned uaperl~o~rd pieces ~or t~le ~)urpose of packay~ng, protectiny.
in~ulating, and disLlayincJ otllee products.

~ck~round of the Invention V~ us ~o~med shaped packaging~ are well known.
Packaging wl~icl~ has a c~nEorming space to the product it cont in8 ~nd in ~qt~icl~ tlle lro~uct is ~nuggly ~it has be~ome well known a~
lt not only protect~ tlle L.~ro~uct but also produces a distinct ve and aesthetlc promotl~nal col-tainer. ~or example, ex~en~ive consu~er goo~s sllch ~8 l~ottled perfulnes, bottled or canned ~o ds, fruits, cflndles, alld tlle lil:e, are sold in this type oF
packagin~ orll~ed and ~ ed package is most e~EectiYe in ha~ldling such gsods d~rincJ stvra~e and transporta~ion a~ well as in ~isplaying tlle ~oo~ls at tl~e point of pucchase.

~ or a long tilne n~o~t produc~ paokages we~e for~ed o papee or c~rdboaed materials. Such ~aterials were easy to pe mit one to provide attracti~e ~isplays and to provide the necessa Y
~r~ntecl in~ocmatloll ~or use oL the produ~t.
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More Lecently, plastics have taken a pro~inent posi :ion -, as tbe ~aterial o~ choice for shaped and product conforming p~ckaging because it can easily be molde~ into a vaLiety o 2 ~ 8 2 apes, ~izes, and colors in accord wi~h ~he need~ o~ the pro~ uc~
as aforementioned. Iiowevee, ~oday's society has increasingly focused upon the neyative environmental conse~uences presentec by the u~e oE plastics, particularly in packagin~, where the material is o~tell ~lisca~de~l shortly aE~er purchase o the pro uct tllerein, ~nother draw~ack of plastic material is that it i8 ard to work ~7itl1, reqUirill~J experienced operators and special equi~men~, paeticularly vacuum ~o~ming mo~ds using excessive amoullts o~ el-ergy.

Packaging materials made ~om paper~oard o~ercome t e environmelltal con~equences o plastic packaging material beca se oE ~ts ~u~erior ~iodegraclability. Unfor~unate~, paperboard material doe~ not llave the ~o~mability oE pl~stics and must o ~en be made b~ c~tting, foldin~, and gluing into the de~ire~ shap .
This procedure l~as tl~e dra~backs o having additional steps i the m~llu~acturlng proces~ thereby incroasin~ the ti~e and co t necessary to pro~uce sucb packaging in addition to generatlng ; was~e. Paperboard packages have the disadvantages of be~ng eelatively ea~y to distort and dest~oy during tran~port, and hey are not sta~le wlle~ et or exposed to extremes o~ ligh~, heat and llumidity.

It is the object oE t~le present in~ntion to pro~tid a shaped, product c~nforn~ing paGkage which embodies the charac~eristics o~ ~oth pa~erboard and plastics withou~ the disad~tan~ages and ecological drawbacks of eith~r.

2~8882 ` It is anotller objec~ of the present invent;on to :.
p~ovide a p~oduct packa~in~ mate~al having the ~avorable biodeyradability ~aLacte~istics of papecboard.

It is anotlle~ object o~ ~he pre5e~t invention to provide A sU~fiCiel-tly rigid paperboard packa~ing material ab e to contain, protect, insula~e, or display the product theee~n It is yet another objec~ of the present invention t ~vi~ a ~a~r~ard ya~kayin~ mate~ial whi~ al~ ~ m~1~3ed i t~
col~plex ~ha~es without need for ~utting, foldin~, and g1uing nto shape .

~ t i~ ~till ano~her object of the pre~ent invention t~
provlde a process foc 1n~1ding a basically paperboard materlal into packaging material wl~ile satis~ying the a~orementioned ob~ect~.

Otller object~ and advantages o the pce~ent invent~ n ~ill be ~pparent to tl~ose skll1ed in the drt from the followi 9 di~losure.

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In accordance wi~h the pre~ent invention, a novel package is provided comprising a molded shaped body formed of paperboard impregnated with a water soluble and b~odegradable latex pol~mer. The impreglla~d paperboa~d 18 placed in an op n mold ~lheee it is Eorme(l int~ a ~peci~ic peedetermined shape u der molsture~ hQAt and pre~ure. Dur ng the ~olding, the latex ~ . .

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''' ~82 r ~ymer ls subjected to s~ch heat that it Elow~ and fu~es together ihtO a cured antl rigid state, in~orpocat~ng therewlth the fibro~s material of the paperboard.

Full details oE tlle ~resent invention are set forth in t~le ollowlng ~3escription.

srie~ ~escriP~ion ~f t~le ~r~willq~

~ iy. 1 iY a perspective vie~ o a package made in accordallce witl~ the present in~ention; an~
Fig. 2 is a perspective view of another package made in accordance ~it~l the U~esent invention.

~ etaile~ Description_of the Pre e~t In~en~ion e package of tl~e preaent inventi~n is constcucted f a paperboard sheet stock c~mprising a mixt~e of a major portil n o~ comminuted cellulose ~ibers and a minor portion of an uncurl d water s~lu~le and ~iodegradable latex polymer binder, cast and rolle~ by con~entiol-al meth~ds. Preferably, the cellulo~e and latex polymer oere u~ orinl~ mixed so that ~he polymer impregnates and ~urcoullds ~he cellulose fiber~ ~niformly prior ~o the casting into tl~a sheet orm. IE desired, additional co~ponents may llave ~een added to the nlixture su~h as colorin~
agents, pow~ers, flecks, and the like.

The polymer impregnated paperbo~rd is aut into a shee t of desire~ working siæe and heate~ to a tempeeature just below the gla~s tran~i~ion point of the polymer and thereafter cbarge 8 ~
- to an open m~ a~ g male and female halves of ~he desire sh~pe ~or ultimate ~ackag~ng or p~oduct. The ~old is pr~heate to avoi~ pl,ase c11a1l9e to tlle surface of the shee~, and thereaf er the temper~ture of tlle mold is raised to elevate the tempe~atu e oE the imp~egnated ~a~eeboard to the fusion point of t11e latex polymer. The shee~ is simultaneously compeessed on ~losing th mol~ and is ke~t in t~e heated mold fvr a time s~ficient to fully cure the latex ~olymer and thu~ ~orm a rigid ~h~ped ~orm It is preferred that the impregnated paperboard shee be intro~uced into the mold while warm ~nd ~omewhat aoistened.
In thls way ~reater Euel economy i~ obt~ined AS a ~esul~ of no }1avin~ to 11eat ~1~e sheet excessively in the mold. Tbe premoistened sheet is ~clvantageous ln pro~iding a satura~ed tle t in the mol~ wllich is able to penetcate tlrough t~le enti~e ~}-ee foe more even molding. Upon removal of the completed molded forln, tl~e forme~ ~ackacJe bo~y is allowed to air cool and final ~et and ~ixed.

Conventional male an~ ~emale compression molds may b ~sed. The mold may be nla~e in an~ shape or si~e ~onforming to the pro~uct to ~e contained in the ~inal package, although it s ~referre~ that tlley 4e provided ~ith radiused edges and matin~
lnterior ~raw angle~ ~ yeeater than 90~ so that sharp corners r I-idden cavities are avoi~ed. Clearances between the mold halv~ g ~ill be xele~ted itl de~ell~ence upon tlle product to ~e made, although it is preferre~ to maintain such clearances to a n~inin lm ln oeder to ~imultaneously comptess ~nd densiEy the wall thickness of the sl-eet. . ....

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2~ 82 ~ ~uitable im~re~nated paperboard stock i~ provided Y
James Ri~er Corporati~n ~ Fitchburg, ~lassachu~etts, ~nder the pro-luct name J~101-5~. Tl~is s~ock material is a mixture o relati~ely s~lort i~er~ with about 30 percent o~ an uncured la ex polylner. T~e mat~rial ig rocmed and supplied in a Lelatively endle~s roll o~ s~lee~ o~ a thicknes~ between about .~30 and .0 4 gauge. SUCI1 material i~ kno-~h only for use as coun~erboara in a di~ press ambossing operation and has never ~een use~ to mold compeessed shaped pro~lucts or packaging. Other startin~
~aterials having lotlger pulp ~iber, dif~erent poly~er c~n~ent, an~ ~leavier material gau~e may be used ~or specific Eorming application~.

The startln~ pa~erboard may ~e made by castin~ and~o colling an aqueous slurry of fibrous stock into thickness from about 0.010 gauge l:o a~out 0.0~10 g~uge. The nature of the fib r stock in the paperboard sheet i~ not critical, but the fibers sl~ould not ~e so pretreate~ as to reject or not bind ultimatel ~itl~ the lat~x l~olymeL. The paper ~ulp may be oE long or shor ~ibecs or a mixture tl~ereo~ ic~ may ral-ge between 1 and 5 mm.
~ypical ~E ll~rdwood~ (~hort fiber~) an~ so~twoods (lony ~ibers) that are u~d by pa~ermaker6. the impregna~ed paperboard mat~ri 1 may lla~e pure cellulose or convelltional cellulo~e mixtures wlth or without additives such a~ soluble binders, st~rahes, coloe ln9~, etc . ~efore mixture witll tbe latex polym~r . It may e ~i~gin stock or recycled mateeial.

Tl~e latex polyme~ used in the manufactl~re of such pap r ~tock may be of ~he t~pe used currently in the ~ormation of mil contalner~ or carton~ should a nontoxic, biode~radable end 2~5~182 o~uct be desired, an~ ceferences ~o the speciEicati~n oE suc productg can ~e easily incorporated herein. ~ water dispersed non~lammable latex is preferred. O~her t~pes of la~ex polymer.
may also be use~. Sucl~ polymers are exempli~iea by:
styrene/buta~iene c~olymers, vinyl ac~tate poly~inyl cllloride 4O1yacrylate esters, and polymet~acryla~e e8ters. In the pape~
stock tlle anl~ullt of l~tex ~olymer should be between 20 to 4~
peL~nt. ~n amount ~f flbout 30 percent is o~nd mos~ desirabl .
The percent is takell by ~eight ~hro~hout the disclosure.

~ leating of t~e impregnated paperbo~rd sheet may be accomplislled in sui~a~ly humidi~ied, heated autoclaves, while t he mold may be conventional ~llern~o~orming equipment. The telnperatuce durin~ molding i~ kept be~we~n about lS0 and 300 degree3 Faren~leit, dependilly upon the impregnation density and material gauge. Pre~erably, a range of between 200 and 250 de9rees ~arenheit pco~uces the mo~t op~imum results. ~ sma}l amount of water or steam may is deslrably sprayed on the paper~oard prior to cori~pressioll to promote uniform heat dispersiol~ and ultimate polynler binding and formability.
TllermoEorming is usually collducted at or above the glas~
transition telllperature o~ ~he polymer ~ choice.

Pressure on ~he impregnated paperboard sheet wi~hin t e mold may be as high as 300 to 40~ p8i to in~ure proper shaping upon set up o~ tlle latex pol~mer. af course, pressure and ~emperature can ~e varied to suit tl~e woLking mat~rlal. During ~ompre~sion, the ~hi~knes6 oE the impreg~ated paperboacd ~heet s redu~ed (i~e. density increased~ a~ a result of the smaller mol Gepdcatlon to about 2/3 tbe stactlng thicknec6. This Increaoes¦

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21D~ ~82 ` ~
~trength and ri~idl~ ut still maintains the paperboard signifi~antly le~s frl~le t~lan ordin~ry plastic sheet. The ¦
sheet is hel~ in tlle rnold ~or betwee1~ S seconds to several minutes depen~in~ upon ~1~e t~1ic1.ness, polymer, and otl1er ~actqr~.

T1le end ~rv~uct ~ape m~y be augmented with ribs, flanges, tabs, and o~1er variations during the n1oldiny staye t o conforln to the end use to wllich the p~oduc~ is to be put.
V~rious ~yes al1d colorations may be included in the impre~nate mixture prior to mol~ing, ~nd the finis1le~ pro~u~t may be imprin~ed and col~red as desired.

Althou~h tllo paper stock is ~ubjec~ed to heat and pres~ure, settin~ ~ the yolymer does not convert the polymer a non~olu~le state, an~ t1~e finished product remains ea~ily ~odegradable.

T1)e following are speci~ic examples.

~X~flP~E 1 A s1~et o appLoxi~ately 4 x 4 inche~ is cut ~ro1n a roll of JRl01-5S4, Jame-~ River paper sto~k, having a guage o~
about 0.0~. The ~to~k ~s moi~ened and placed in an oven containinq a nlois~ure keeping heat. The stock is heated slowl~
to about a 2U0 degLee temperatur~ ~i.e. the glass tran~istion , point o$ the polymer). It i5 then placed ov~r the ~emale por~: 1on of an open, preheated tllermo~orming mold (with a~proximately a .00~3 clearance froln male to female). The boa~like body (se~
Fig. l~, ha~ing a cavity in which may be nestled a peL~ume b~ttle. T~,e mold i8 closed at abou~ 300 psi and ret ~5 ~e8 preheat temperatu~e o~ ~0~ clegrees. The sheet is kept ln the mold under pressure for about S ~econds, and tlle latex in the sheet sets into a fiY.ed ~orm. The molded body is ~hen removed~
~nd allo~7ed to cool. ~t may be used in this ~orm.

EXAlPLE II

~ paper stock starting material i8 ~ormed comprising a slurry contail-ing a~out 70 pe~cent of subs~antially long fiber (an average length of about 4nlm), cellulo~e fiber~, both virgi~
and eeclaimed, and 30 ~ercent of a styrene/~utadiene copolymer.' The sl~rey is mixecl until llolnogeneous and rolled into a sheet t Y
the usual method.

A web of ~pproxi~ately 12 x 12 inche~ i~ cut ~rom the rolle~ eet and run throu~h a long moisturé retainlng heated oven. Th~ ~eb is thell preheated to 250 degrees, after which it is inserte~l into the tl~ermoforming mold ~s in Example I. ~he mold, however, is ~ormed to provide a bocly ~lat on one surface and corrugate~ ~n ~lle otller sue~ace tFig. 2). Th~ corrugated sur~ace llas closely orme~ ridges and ~alleys. The body is molded at a tempeeat~r~ of about 350 deg~ees at a pressure of 4~0 ~si foc about 20 ~econd~. Tl~e long fiber~ are adv~ntageous in :~ formlng permanent close rldges and ~alleys, ~l~ile the added pcessure provides for increased den~ity and strength. Upon coolih~ the molde~ sl~eet ~as folded into a box-like ~orn~.

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.. .EX~PLE III 20~8182 Example ~I was ~ollowed ex~ept th~t the proportion o~
latex to cellulose was increased to a ratio of 40 p/S/i o~ lat~x to about 60 ~/s/i ~ cellulose. The late~: was a polyacrylate ester And the temueratur~ ~educed to 250 due to the lncreased proportion o~ tlle E)oi.yliler. ., EX~llPLE IV

Example II wa~ followed exce~ that the paper stock ;
~ontaine~ 80 per~ent cellulose long fibers ~average 7 mm) and ~n . percent latex polymer; a r,lol~ wax used providing ~orruga~ions on the surf~ee o~ the slleet exterior of the cavity ~or the object an~ the slleet was bel~l in tlle m~ld for one minute. The prWes~
l8 c~pable o~ peoducin~ packaglng of multiple shapes ~nd form8.

Various mo~i~ications, change~, and embodi~ents have been ~isclosed, and otllers will be obvious to those skilled in t1~is art. ~ccordin~ly, it iS intended that the oregoing d~sclosure be taken as illusteative only and not limiting o~ th e scope oE the invelltion.
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Claims

WHAT IS CLAIMED IS:

l. A process for preparing a formed paperboard body comprising the steps of providing a paperboard sheet having a major portion of cellulose fibers and a minor portion of an uncured latex polymer, introducing said sheet into a mold having the shape of the desired body and subjecting said sheet to heat and pressure to form said body and set said latex into fixed forms removing said body from said mold; and cooling said body.
2. The process according to Claim 1, wherein said paperboard is formed from an aqueous slurry of between 60 and 80 percent cellulose fibers and about 20 to 40 percent latex polymer.
3. The process according to Claim 2, wherein said latex polymer is selected from the group consisting of styrene/butadiene copolymers, vinyl acetate polyvinyl chloride, polyacrylate esters, and polymethacrylate esters.
4. The proxy according to Claim 1, wherein said mold is held at a temperature of between 150 and 30 degrees Farenheit, the pressure is held between 300 and 400 percent, and the time of molding is between 5 seconds and 1 minute.
5. A paperboard package comprising a molded body formed of a web of paperboard comprising major protion of cellulose fibers and a minor portion of an uncured latex polymer, said body being molded under heat and pressure for a time sufficient to cause said latex polymer to flow and fix in form upon cooling.
6. The paperboard package according to Claim 5, wherein said paperboard is formed from an aqueous slurry of between 60 and 80 percent cellulose fibers and about 20 to 40 percent latex polymer.
7. The paperboard package according to Claim 6, wherein said latex polymer is selected from the group consisting said latex polymer is selected from the group consisting of styrene/butadiene copolymers, vinyl acetate polyvinyl chloride, polyacrylate esters, and polymethacrylate esters.
8. The paperboard package according to Claim 5, wherein said mold is held at a temperature of between 150 and 30 degrees Farenheit, the pressure is held between 300 and 400 percent, and the time of molding is between 5 seconds and 1 minute.