wogul~u~ 2 i 8 2 9 8 3 r~s9al~
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,
BAG AND MFTHOD FOR PACi-<AGlNG GRANIll A~ COMPOUNDS
u uu~d Uf me Invent~ûn
The present invention ~eneraily relates to 8 b~ and
method for ~ ranular compounds, ~ lead-based,
dust-prone ~ranular compounds.
Lead-based compounds such as dibssic lead phthalate,
tribasic lead sulfate, dibasic lead phosphite, dibasic and normal lead
stearates, as well as others, are col"iJ~ d some of the most
effective and least ~A~,e....;~r~ pol~v;.,,~l~.l,lu.ida (PVC) heat ' " :,.
Lead-based compounds such as these are widely used as additives in
r 10 many ~ 5 using PVC, such as in the extrusion of wire
coverin~s, despite their chronic toxicity. It is also well known that
chronic toxicity problems involvini~ lead-based compounds may be
avoided by ~ ~a~ a inhalation and in~estion of airborne dusts
wo srillOos42 2 1 8 2 9 8 3 1 ~-".~
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~" , ,9 these lead compounds. ~lor,~tl,~iu..~
precautions against inhalation and ingestion are often not taken by
the personnel handling lead-based powders during the batch
~,u-.~ss;,l~ of PVC.
One possible solution to the problem includes isolating
the lead-based powders, or other dust-prone forms of lead-based
compounds, within a contained system which would not expose the
personnel to airborne, lead-c~" ~9 dust created durin~ batch
p~U~GSS;~9. Another possible solut~on ~s to utilize lead-based PVC
heat ' :. which have been ~u~,G;~ d into a "non-dusting"
form, i.e., a form which does not create the airborne c~"l .., ,el"l:,
created by powdars. Such non-dusting forms include, for example,
prills and pastes. The i, ' ) of cc"" ' ~ contained systems is
very ~A,u~n~h/ and is therefore not a practical solution for most
i.~" ~s. The use of lead-based compounds in non-dusting form
aiso adds expense and, in addition, reduces the ease of ill..~l~JOlali"g
the lead stabilizer into the PVC and leaves the problem of container
disposal which is of critical 611J;lUlllllelll~ Jullal)c~.
A low melting temperature ethylene vinyl acetate
copoly."~r lEVA~ film has been disclosed in U.S. Patant No.
5,120,787 ~the '787 patent) as being useful for makin~ bags and
compounding tub liners. The '787 patent discloses that rubber
dL~Jel:~iull:> contained in the bags or tub iiners may then be added to
hi~ih intensive mixers whereupon the contents thereof are mixed into
2~ 82983
WO 96118S42 P~, 11 ., ~., ~1 1~.. ,~.
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the other contents ~n the mixer. The EVA film ~ melts and
disperses into the mixture.
The '787 pstent, however, does not disclose any
solution to the specific problems r--- ' ' ' with lesd-based
powders. In this re~ard, while the formation of b~s from low
meltin~ temperature EVA film is ~enerally disclosed by the patent,
the ~ of lead-based compounds in bs~s formed from this
EVA film presents ~;ulliri~.a~lL ~ ' For example, lead stabilizer
powders are hi~hly ener~y absorptive and, for this reason, they will
often prevent the effective heat or ultrasonic sealin3 of the ba~
opening merely by be bein~ present at the open ed~es durin~ the
heat sealin~ operation. An ineffective seal at the bag openin~ may
take the form of either an actual leak or a ~ ed portion of the
seal which is likely to break open and cause a leak. The hi~h density
of the lead-based stabilizer powders t~.a~ iJaL~ the problem by
creatin~ leaks throur~h physical pressure applied at portions of the
seal v,~ ' ~ed du~ to the presence of the lead stabilizer powder
durin~ the sealing operation.
Certain ba~s have also been ~enerally disclosed with
fillin~ spouts havin~ a reduced diameter. Such barJs are ~ rl~s~d.
for example, in U.S. Patent Nos. 2,918,958; 3,016,284; 3,051,605;
and 3,208,661. These ba~s are not, however, directed to the
specific problems III~IILi~ d above with respect to the pdC
and co, Illle:llL of lead-based stabilizer compounds.
WO 96rl8542 2 1 8 2 ~ 8 3 PClNS95rl5958 0
It would therefore be desirable to provide 8 ba~ and a
method of ~ o~ ,d or other dust-prone forms of lead-
based heat stabilizer compounds which would ensure full, ~ffective
sealin~ of the ba~ and its contents and allow the ba~ to be
~ r melted and dispersed when used, for example, in the
batch p,u.,es~ of PVC.
Summ~nr of th~ Invention
The present ~nvention is directed to a ba~ and a method
of, ' _ ,~ ~ranular compounds, such as dust-prone, lead-based
h~at stabilizer compounds. More _, _ '' `Iy, especially when
F ~ lead-based compounds, the ba~ is formed frorn a
Lll .,. ,' film which is ~.uf~..dl,ly a low molecular wei~ht EVA
film. The ba~ is initially sealed around suL .Ic.. 'Iy its ~ntire
periphery prior to fillin~ the ba~ with the lead-based h~at stabilizer
compound. The ba~ includes a main body portion and a reduced
diameter spout port~on or "snorkel rrlouth" extendin~ outwardly
r,u..,. ~,~r~,aLly, the spout portion axtends laterally from the
main body portion of the bag adjacent to one end thereof. The
spout portion is sealed about its periphery but includes an open end
throush which the ba~ may be filled with lead stabilizer compound
by an inserted fillin~ tube.
The end of the spout portion ~ rt:laLly includes a cuff
which is folded back onto the spout portion. This cuff ensures that
lead stabilizer compound does not contact the outer, unsealed ed~es
21 82:983
wo 96118542 r~
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of the spout port~on durinaO the filling operation. That is since the
outer unsealed ednOes of the spout portion sre folded over onto the
outs~de of the spout port~on. contact w~th the lead stab~l~zcr
compound be~nO ~ o~d ~nto the baO is ~ . tvd. Thls
combined with the isolatinnO effect of the spout port~on ~tself helps
to . ~ prevent cu.lL~IIl;.l_~iu.. of the outer unsealed edOes by
lead stab~l~zer compound. As ~ ion~ above due to the enernOy
absorpt~v~ ~ .up_.li~s of lead based compounds such C~lllalll l~livn
would often result in d~srupt~nOn the heat or ultrason~c seal~nOn thereof
after the f~ nnO operst~on and therefore create a w~ I d or leak~nû
area in the seal. In add~t~on the isolated location and relatively small
iVI~ of the spout portion further prevent ~iU~Iiric~ l amounts
of phys~cal pressure from be~nO exerted on the f~na~ outer seal
thereof.
The method of ~ k_o ~rO lead-based stab~l~zer
compounds ac~ to the present ~nvent~on ~ncludes prov~d~nnO a
ba~ havinû a ma~n body port~on and a spout port~on extend~n~
I~l_. :rlulll by seal~nnO around the ent~re per~phery of the ma~n body
port~on but leav~n~ an outer end of the spout port~on open. The
outer ûpen end of the spout port~on ~s folded back ~nto a cuff. A
filling tube is inserted into the spout portion and the banO is filled with
a dust-prone lead-based stabil~zer compound which may be a
powder. When the banO is full the fillin~ tube is ~: ~v . . .l from the
spout portion and the cuff is unfolded. The outer open end of the
~ 82~8~
W096/18542 1~.I11~.NI~,./ O
spout portion is then sealed by 8 heat sealin~ procedure. In this
renOard, as used throuOahout the al - ~ir;~.l;nn and claims, the term
heat seal" broadly l..~G~ ,; other forms of sealin~ by the use
of radiant enernOy, such as uitrasonic enernoy~ In the preferred
b ~ " ,l, a defined hld line is formed by the cuff to indicate the
u"c~, , ' area of the spout portion which should receive the
heat or ultrasonic seal.
It is further c~ Jldt~d that tha "snorkel mouth- banO
construction which includes the cuff and fold line for the purpose
indicated above may be useful in 8=,, " ' i~ other than the
_ ~d of dust-prone lead-based compounds. Therefore, for any
nOranular compound which would tend, for example, to interfere with
the heat sealinnO of a baOn as ",o.,lioncJ above, the use of a ba~
havinnO a cuffed spout portion inlcudinnO a defined fold line for
indicatinnO where the final heat seal should be made would be
part~cularly 6~va,~lalOeous.
The banOs and j~a k~O ~nO methods of this invention,
alonnO with the various advantanOes and other aspQCts thereof, will be
further ulld~ ùod with reference to the followinnO detailed
des~ Liuil thereof taken in conjunction with the acc~""~6"yinnO
drawin~s.
Brlef D~3c,i~ of the Drawlng~
FinO. 1 iS a front ~ aLiullcll view of a banO formed
accordinnO to the present invention and shown in an empty conditiûn;
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O WO 96/18542 PCI/US95/15958
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Fi~q. 2 is a front . :. - 7~1 view of a ba~ as in Fi~j. 1
but showin~ a fillin~ tube inserted to fill the ba3 with lead-based
stabilizer powder; and,
Fi~. 3 is a front Llv /.~tiO~Ial view of a bag as in Figs. 1
and 2 but showin~ the bâ~ f~lled with a quantity of lead-based
stab~lizer compound and c~", ~ sealed.
De- Dv~ n of the PreferrQd E~rh~clirnent
Referrin~ to Fi~s. 1 and 2, a lvad stabilizer ba~ 10 made
a ,cv" 7~ to the a preferred L.,IL- lalll of the invention is
illustrated. S~ - Iy, ba~ 10 includes two sheets 12, 14 (Fi~j. 2)
of polymer film. The film is a heat sealable, low molecular wel~jht
ethylene vinyl acetate ~vopolv,nv~ (EVAl havin~ a low meltin~j po~nt,
~vfv.ai;l~ below about 170 F. The preferred EVA copolyn~
useful in the ba~ and method of the present invention are disclosed
in U.S. i atent No. 5,120,787 (the 787 patent), the disclosure of
wh~ch is hereby fully and expressly i~lvul~ulatvd herein by reference.
Generally, the EVA cop~ly.,,v, used in forminov ba~ 10 includes a
vinyl acetate content of at least about 25% and may include other
resins, fillers and additives, such as those disclosed in the 787
patent, while lll ~ ~d the low meltin~ temperature and heat
seâling plup~ s thereof.
Ba~ 10 is initially formed by sealin~ peripheral ed~es
16, 18, 20, 22 and 24 to~ether, as by heat or ultrasonic seals. As
further shown in Fi~. 1, for exsmple, ba~ 10 includes a reduced
WO96118542 2~ 3 PCTIUS95/15958
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diameter spout port~on 26 eAl~ laterally from a main body
portion 27. Spout portion 26 ~S defined between ed~es 24 and 16
of ba~ 10. In the ba~'s empty state shown in Fi~. 1, spout port~on
26 includes two unsealed, outer edges 28 which definQ the only
6 openin~ to bai~ 10. Spout portion 26 further includes a discrete foid
line 30 at a distance spaced inwardly from outer ed~es 28. Fold lin~
30 iS ~lufu..Jijly a crease in spout portion 26. The distance between
fold line and outer ed~es 28 may be, for exampie, SIPPIUA;~ IY 2
inches when spout portion 26 has a len~th of about 63~ inches and
a width of about 51/~.", and main body portion 27 has a len~ith of
about 28 inches and a width of about 13 inches.
As shown in Fi~. 2, the outer end of spout portion 26
msy be folded back into a cuff 31 defined between outer ~d~es 28
and foid line 30. Durini3 a fillin~ operation, a flll tube 32 is inserted
throu~h spout portion 26 and into main body portion 27 of ba~ 10.
Fill tube 32 includes a conver~in~i open end 34 to aid in the insertion
thereof and to allow lead stabilizer compound 36 to b~ ,l)a,ued
~nto bag 10. As --t:llli~ned above, any of the typical lead-based PVC
hest stabili2er compounds, in iJL..J~lt t~d or other dust-prone forms,
may be introduced into the bai; dep~ on the needs of the
~rr. ~ or the desires of the end user. Thes~ msy include, for
example, pO.Jd~ i forms of dibasic lead phthalate, tribasic lead
sulfate, dibasic lead phosphite, ~nd dibasic or normal lead stearates.
When ba~ 10 is filled with the desired amount of lead-based
21 82983
~I W0 96/18s42 r~ 5,~
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stabiiizer powder 36, such as thr~ exsct amount required to bo add~d
to a PVC batch mixer, fillinq tube 32 is . h i~ , cuff 31 (FiEj. 2~ ~s
unfolded and a final heat seal 38 i5 placed between outer ed~es 28
and fold line 30 as shown ~n Fi~. 3.
Referrin~ now to Firjs. 1-3, the preferred method of
_ rj lead-based stabilizer powders in a ba~ 10 of the present
invention includes providinrJ ba~ 10 with a main body portion 27 and
a spout portion 26 ".t~ Ll ~,r,..~.. with bsrJ ~0 includin~
'~ sealed edEies around suL;.Ia., 'I~ the entire periphery
thereof, i.e., at edges 16, 18, 20, 22 and 24, while leavin~ an outer
end 28 of spout portion 26 open. The outer, open end 28 of spout
portion 26 is folded back into a cuff 31 (Fi~. 2~ at fold line 30,
f~.dLI~ well prior to the ins~rtion of fillinrj tube 32 for the
purposes of speedinrj the ~ process. FillinEj tube 32 is
inserted into spout portion 26 and ba~ 10 is filled with a dust-prone
lead-based stabilizer compound 36, such as a powder. When ba~ 10
is filled with the desired amount of lead stabilizer powder 36, fillin~
tube 32 is .;tl~ .., from spout portion 26 and cuff 31 is unfolded
as shown in Fig. 3. Usin~ outer edEjes 28 and fold line 30 of spout
portions as boundary lines markin~ the area of spout portion 26
~llc~nllalll lal~i by lead stabilizer powder 36, a final heat seal 38 is
applied lI.~ to cc.,., ': '~ seal the periphery of ba~ 10.
Ba~ 10 may then be added to a PVC mixer whereupon it will melt
and c~.., ': 'y disperse in the PVC.
WO 96/18542 ~ 3 PCT/US951159~8 ~
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By way of the fore~o~n~, it will be ~p~ that a
ba~ and method for, E ,~ dust-prons l~ad stabilizer compound
has been provided with the combined ~ of onablin~ fast,
efficient addition of put~... Iy hazardous lead compounds to PVC
5 m~xers while .. , .. i ;,.~q exposure of personnel to airborne particles
c~.. ..~ Iead compounds~
It is cvll~ that the unique ~" ,~-tiu-, of a
Il, ." ~ ba3 hav~n~ a cuffed spout portion as descr~bed above
would be ~v.,.I~ us for ~p~ .. other than the lead stab~l~zer
~,1, n detailed above but in wh~ch sim~lar problems may ex~st.
For these reasons, the invention in th~s broader aspect, should not be
lim~ted to the d~ta~ls ~ven here~n w~th respect to lead-based
compounds.
Wh~le preferred u.llL ".,.,l~ of the present invent~on
have been descr~bed above, vsrious Illu~l~ri-,aLi~lls w~ll become
resd~ly sppsrent to those of ordinary skill without departin~ from the
sp~r~t and scope of the invention and Applicant therefore intends to
be bound oniy by the clsims appended hereto.
