Note: Descriptions are shown in the official language in which they were submitted.
i~ 745iSS
MET~OD FOR PROTECTING IUMEE:R
The pre~ent invention relate~ to a method for
protecting ~tacks o~ lumber, during transportation and
~torage outdoors.
During tran~portation and torage o~ lumbe:r~
esp~ially dre~sed lumber~ it i8 desir~b l~ to protect th~
lumber from the vagarles o~ the weather, in order to pre-
vent soillng and~or watPr ætaining of the lumber.
It i~ known to co~er lumber ~ith a wr~pping
~aterial. Example~ of such wrapping materials are a wo~en
glas~ fibre web laminated on both`side~ to kra~t paper, a
~erim o~ ~oven polyole~in tape~ laminated to kra~t p~per,
clear pol~ethylene ~ilm, polyethylene ~ilm ~illed with
carbon black pigment, and a ~crim o~ Noven polyole~in tapes
15 : coated with a layer Or pol~ethylene ~illed with TiO2. Ih
general the kra~t paper laminates tend to ~e dama~ed dur~ng
long distance transportation, which may lead to los~ of
protection. Lumber wrapped ln the a~orementioned polyet~y-
lene ~ilm m~terials tend to become water stained~ mildewedQ and/or warped.
an ob~ect o~ the pre3ent ~nvention to pro-
~ide a method o~ protectin~ lumber which tend~ to o~ercome
the d~lci~ncles Or methods o~ the prior artc
Accordingl~ tho present inventio~ provide~ a
method ~or protectlng lumbe~ comprl~ing co~ering a ~tack o~
lumber on at least its upper, 3ide and end ~ur~ces with a
wrapping mate~ial selected ~rom the group con~l~ting o~
a) a fabric made ~rom wo~en oriented tape~ o~ pol~ethylene,
~aid ~abric be~ng coated with a layer o~ polyethylene at
least about 15 ~m in thickne~s containin~ a particulate
~'
~ 7~S S 5
metallic ~iller ~elected ~rom the group cons~ sting of
aluminum, brass and bronze, in an amount ~u~ficient to
provide a light transmitt~nce through the wrapping ma-
terial in the 450 to 700 nm wavelength range o~ less than
about 30~, and b) a ~abric made ~rom woven oriented tapes
of polypropylene, ~aid ~abric being coated with a layer
of polypropylene at lea~t about 15 ~m in thickness con-
taining a particulate met~llic ~iller selected from the
group consisting o~ aluminum, brass and bronze, in an
amount su~icient to provide a light transmittance
through the wrapping mæterial in the 450 to 700 nm wa~e-
length range o~ less than about 30~.
In a pre~erred embodiment o~ the me~hod Q~ the
pre~ent invention the wrapping m~terial has a coating
containing aluminum particulate ~iller, especially aluminum
in ~lake ~orm.
In Ano~her embodiment the ~abric o~ ~oven tapeæ
has a crowdedness of between about 20~ and 70~ in the we~t
direction and between about 30% and 100~ in the warp
d~rection. Crowdedness i~ de~ined as the ratio, expre3sed
as a percentage, of the area o~ the fabric occupied by
either the ~e~t or the warp tapes to the total area of
the fabric.
In yet another embodiment the particulate metallic
~iller i8 pre8ent in an amount su~ficien~ to provide a
light transmittance in the 450 to 700 nm wavelength range
o~ les~ than about 2~%.
The pres2nt invention also pro~ide~ a lumber
co~r hav~ng a t~p panel, two ~ide panels and two end
panel8, ~aid panels being made o~ a wrapping material
selected ~rom the group con~i~tlng o~ a) a fabric made
rrom ~ro~ren orlented tapes o~ polyethylene, said ~abrlc
being co~ted with a layer Or polyethylene at least about
15 ,um in thlckness containing a partlculate metallic
35 ~iller selected from the group consisting o~ aluminum,
bras~ and bronze, in an ~mount su~ricient to provide a
light transmittance through the wrapping material in
~7~S55
--3--
the 450 to 700 nm wavelength range o~ less than about
30%, and b) a fabric made from woven oriented tapes
of polypropylene~ said ~abric being co~ted ~ith a layer
of polypropylene at least about 15 um in thiGkne~s con-
taining a p~rticulate metallic ~iller ,selected ~rom thegroup consi~ting of aluminwm, brass and bron~e J in an
amount sufficient to provide a light transmittance through
the wrapping material in the 450 to 700 nm w~velsn~th range
o~ less than about 30~, said panels being o~ a size such
that the cover substantially con~orm~ to a rectangul~r
pri~oidal ~tack o~ lumber.
I~ a preferred embodiment of the lumber cover o~
the present invention the sd~oining edges o~ the panel~
are he~t sea}ed.
In a ~urther embodiment the ad~oining edges of
the panel~ are ~ewn.
In another embodiment the end and top panels are
made ~rom a ~ingle piece o~ the wrapping material.
In yet another embodiment the coating o~ the
lumber co~er is between about 15 ~m and 50 ~m and contains
aluminum as the particulate metallic ~iller.
In a further embodiment the wrapping material o~
the lumber co~er is polyethylene.
The present in~ention ~urther provides a ~tack of
lumber co~ered on at least its upper, side and end surfaces
with a wrapping material seleeted ~rom the ~roup consi~ting
Or a) a ~abxic made ~rom woven oriented tapes of polye~hy-
lene, ~ald Pabric being c~ated with a layer o~ pol~ethylene
at least about 15 ~m in thickness containlng a particula~e
mekall~c ~iller ~elected ~rom the group consi~ting of
aluminumJ br~ and bronæe in an.amount su~icient to pro-
vide a light transmittance through the wrapplng materi81
ln the 450 to 700 nm wavelength range o~ le~ than about
30~, and b) a ~abric made ~rom wo~en oriented tapes o~ poly-
propylene said rabric being coated with a layer o~ polyprop-
lene at least about 15 ~m ln thickness containing a partic-
~3L7~
ulate ~etallic ~iller selected rrom the group consisting ofaluminum, bra~ and bronze in an amount su~ieient to pro-
vide a light transmlttance through the wrapping material
~n the 450 to 700 nm wavelength range o~ less than about
30~.
In a pre~erred embodiment of the stack Or lumber
Or the present invention the coating of` the wrapping m~-
terial contains an aluminum particulat0 ~iller, especially
aluminum in flake form~
In another embodiment the fabric o~ ~oven tap~s
ha~ a crowdednes~ o~ between about 20% and 70% in th~ Ne~t
direction and between ~bout 30% and 100~ ~n the ~rp direc-
tion.
I~ yet another embodiment the oriented t~pes o~
the ~abr~c are made ~rom a polyethylene, havlng a density
between 0.940 and O.g70 g/em3, which is a homopolymer of
eth~lene, a copolymer of et~ylene and a C3-C8 l-ole~in or
blend~ thereo~ espec~lly a homopolymer o~ ethylene and
the coating i8 made ~rom a polyethylene, ha~ing a density
between 0.910 ~nd 0~945 g/cm3, which i3 a homopolymer o~
ethylene, a copolymer o~ ethylene and a C3-C8 l-ole~in or
blend~ thereof~ especially a copolymer o~ ethylene and
butene-1.
In a ~urther embodiment the coating Or the wrap-
ping material has a thicknes~ between about 15 ~m and 50 ~m~
preferably in the ~ange o~ 20 ~m to 30 ~m.
It Will be understood by tho~e ski~led in the art
that t~p~s made ~rom h~m~polymers o~ propylene ~ay be ori-
ented and are ~ui~abl~ ~or maklng the ~abric portion o~ the
wrapp:in~ material. Xt will ~180 be understood that copoly-
mer~ o~ propylene e.g~ wi~h eth~lene are ~uitable rOr
co~ting the polypropylene fabric.
me pre~ent invention relates to a method ~or
protecting lumber~
It is known that polyethylene containing be tween
1 and 5~ of flnely di~ided TiO2 i~ op~que to li~ht having
-5-
a wavelength of le~s than about 400 nm, However structures
o~ wo~en oriented poly~thylene tapas eoated with polyethy
lene containing ~inely divided TiO2 tend to allow lumber
wrapped therein to "s~reat"~ It is believed that s~reatlng
5 is caused by heating of the lumber to s.n exterlt suf~icient
to cause e~aporation o~ the moiQture within the lumber.
Retention o~ the moisture 80 evaporated within the con~ines
Or the wrapping material may lead to mould formation on the
~ur~ce o~ tAe lumber and/or staining.
Replacement of TiO2 in the polyethylene coating
with carbon black ~mprove~ the opacity o~ the ~tructure to
light, by broadening the wa~elength spectrum o~ llght ~hich
is blocked by the pig~ent, to a wa~elength of le~ th~n
about 700 nmO While the use o~ carbon black ~t a concentra-
tion o~ about 2% pre~ents.sub~tantially all light~ having a
waYelength o~ lesæ than about 700 nm, ~rom pas~ing through
the ~aterial, its use doe~ not appear to materially lessen
the problem o~ sweating. Staining o~ the lumber does not
appear to be as evident when a coating of polye~hylene con
taining carbon black i8 used, however, but the lumber has a
tendency to wsrp. Su~h warping is believed to be caused
by rapld dr~ing of the boards on the out~ide of the lumber
stack.
Although not wishing to be bound by any theory~
it appears that the present invention tend~ to overcome the
problem~ presented by the pr~or methods used ~or wrapping
lumber, by minimiæing the amount Or moi~ure removed ~rom
the lumber and le~sening the chance~ o~ light-i~duced stain-
ine 0~ the lumb~r~ It appe~r~ that, in accordance with the
pre~ent invention, total op~city to light is not required
and that light trans~it-tances in the wavelen~th range o~ 450
to 700 nm o~ le~s than 30% is su~icient. Light transmit-
tances o~ less than 20~ are pre~erred, however.
Technique~ ~or manu~acturlng eoated woven polyole~in
materials are kn~l. For example, the wo~en ~abric required
,
7 ~ S ~ 5
~or the pre~ent invention ma~ be wo~en on a loom having a
we~t supply bobbin outside the ~hed o~ warp tape3~ ~rom
oriented tapes slit longitudlnally from sheet~ o~ polyethy-
lene or polypropylene ~ilm. me woven ~abrlc may then be
transported below and past a ~ransversely positioned slot die.
A~ the ~abric passes below the slot d:le, a blend of the coat-
ing polyole~in i.e. polyethylene or pol~propylene, and the
particulate metallic filler i5 ex~rud~d through the slot die
onto the rabric, ~hus ~orming a thin coating on the woYen
~abric. me wrapping materials used in the present in-
~ention are con~en~ently wo~en and coated in width~ Or be-
tween about 245 cm and 275 cm, although there is no reason
why other width~ could not be used~ In the eYent that
ma~erial o~ greater uidth is requlred to ~rap stack~ o~
lumber, two or more ~heets may be cut ~rom a roll o~ the
wrapping material and then m~y be hea~ sealed together
a~ong their longitudinal edges. Heat se~ling m~y be ac-
complished by placing one sheet, with its coatlng facing
upwards3 longitudinally ad~acent to a second sheet, with
its coating ~acing downwards. me longitudinal edges o~ the
two ~heets are o~erlapped so that the coating~ are in ~sce-
to-race relatlonship and the coat~ngs t~en are ~oined by
hot air ~ealing in a known manner, Further sheets may be
heat-sealed to these two in a gimilar manner, in orcler to
obtain wrapping material of e~en greater width. In an
embadim~nt Or the in~ention the sheet~ ~ay be eut to a
len~th e~ual to twice the he~ght plu~ the length o~ the
lumber ~tack to be co~ered.
~or convenlence three sheet~ may be cut longitu-
dinally; two o~ them ~nto widths corre3pondlng to the
height and one o~ them into a width corra~ponding to ~he
width o~ the lumber ~tack to be co~ered~ m e ~heet~ may
then be hea~ ~ealed as hereinbefore described, or ~ewn. m e
longitudinal ~oints so ~ormed may be used to guide the
placement of the wrapp~ng material o~er the lumber.
~7~ ~ S S
A lumber cover may be pre~ormed by folding and
sewing the wrapping material into a ~iv~-panelled cover
i.e. t~o end two ~ide~ and a top. Alternati~ely~ the
lumber cover may be ~ormed by foldlng and stapline or
otherwi~e securing ~he wrapping material a~ter covering
the lumber stack.
The wrapping materials u3ed in ~e present in-
vention are su~icien~ly durable i~ the wo~en fabric
portion is loosely woven i.e. i~ a ~cri.m~ It i~ pre~erred
tha~ the construction o~ the scrim is æu~ficient to ~part
a grab ~trength to the wrapping material in either the ~axp
or we~t direc~ons o~ at least about 110 ~ and more partic-
ul~rly between about 175 and 310 ~, grab ~trength being
measured by the procedure of ASTM-D1682 640
Wrapping material~ ha~ing the desired le~el o~
grab ~rength may be made ~rom a scrim having oriented warp
and we~t tapes o~ polyethylene having a density between
0.940 and 0.970 g~cm3 and a coating o~ polyethylene ha~ng
a den~ity between 0.910 and 0O945 g/cm3. m e scrim may be
constructed ~or example ~rom warp tape~ ha~ing A width
between about 2.0 mm and 3.0 mm and a linear density be-
twee~ about 650 and 1100 dtex and we~t tapes having a width
between about 2.5 mm and 4.4 mm and a linear density between
about 1050 and 1250 dtex, wherein the weave has betw~en
about 3.3 and 3.9 ends/cm and 0.9 and 1.5 picks/cm. me
coatlng is pre~erably between 15 and 50 ~m in thicknes~ and
the concentration o~ aluminum~ bronæeJ or brass in the coat-
ine is p~e~erably in the range o~ OJ75 tO 4.5 wt.~o
The particle shape o~ the metallic pigment iæ not
3~ critical~ but ~lak~ form~ are p~er~rred. ~he plgment
par~icles used in the pre~ent inven~ion need to be o~ a
particle ~l~e that is su~iciently small that the extru~ion
process i~ no-t hlndered~ In general~ particles which pas~
~ through a 325 mesh TYLER* sie~e are ~uitable.
* denotes trade mark
.. .
~ 5 5
me presen-t invention is illu~trated by referen~e
to the followlng e~amples:
Example 1
The e~icacies of an embodiment of the present
ln~ention and methods of the prior art were compaxed ~ith
respect to the ability to suppress mol.~ture evolution ~rom
lumber.
Samples oP wr~pping materials, about 33 cm square
were taken and weighed. Each ~ample was wrapped around a
we~ghed 10 cm x 5 cm x 4 cm block o~ green ash. me b~ccks
of green a~h were cut ~xom a l~rger block to minimize the
varlæb~llty of moi8tur8 content ~rom block to block~ The
~r~pping material~ fully envelop~d the ash block~ ~nd were
stapled thereto. ~he wrapped blocks ~ere placed about
30.5 cm a~ay ~rom a 250 watt bulb of a sunlamp. Each ~r~p
ped block ~as e~posed to ~i~ cycles of 30 minute periods of
heating, with the su~aD~p on, followed by 30 minute periods
o~ cooling, with the ~unla~p off. ~he ~mbient room tem-
perature was about 10C. A~ter 12 hour~ the ash block~
were weighed after removing ~rom the wr~appirlg material ~nd
drying their ~urf`aces with weighed blotting paper. ~he
moist blotting paper wa~ then weighed.
A wrappe~, d2~ign~ted "Clear", used ror comp~rl-
son purpose~9 compri~ed ~ scrim o~ oriented tapes, made
~rom a clear polyethylene having a den~ity of o.960 g/Cm3J
in which th~ warp tape~ had a width o~ 2.5 mm and a linear
den~ity o~ 1067 dtex.and the we~t tape~ had a width o~
3~38 mm and a l~near donslty o~ 1083 dtex and which had
3.55 ends/em and ~.58 pick~/cm, coated with a 25 ~m layer
Or clear pol~thylen0 havln~ a den8it~ of 0.923 g/cm3.
A ~econd wrapper, desi~nated ~White~, also used
~or comparison purpose~ con~l~ted o~ a scrim, ~imilar to
khat o~ the ~Cle~r" wrapper, laminated to a polyethylene
~ilm cont~lnlng about 5~ TiO~ and having a thickne~ o~
25 ~m.
1:~'74SS5
The wrapper de~ignated "AL't, u~ed in the pre-
sent invention comprised a scrim o~ oriented tape~ made
from ~ clear ethylene homopolymer having a density of o.960
g/cm3, in which the warp tape~ had a width o~ 2.5 mm and
5 a linear density oi~ 667 dtex and the weft tapes had a
width oP 4.25 mm ~nd a linear density of 1222 dtex and which
had 3.55 ends/cm and 0.9~ picks/cm, coated with a 20 ~m
layer o~ a mixture o~ 9 parts of clear polyethylene having
a density o~ 0.923 g/cm3, and one part o~ a polyetAylene
10 and aluminum concentrate. me weft crowdednes~ o~ the ~AL"
wrapper is 40% and the warp crowdedness iY 89~
The polyethylene and aluminum concentrate com-
prised flake alumlnum available from the Canbro Divi~ion
o~ International Bro~ze Powders Ltd. o~ Yalleyfield, Quebec
under the trade ~ark LUXOR 950 in a concentration of 25 wt.%
in a pol~rethylene h~ving ~ den~ity of 0.917 g~cm3.
. The result~ of the experiment~ with the "Clear~, :
"White" and "AL" wrapping materials, which ~re ~hown in
Table I, indicate the ~fecti~eness o~ the wrapping materlal
20 o~ the present in~rention in reducing the total amount o~
moisture evolved ~rom ~he lumber, and o~ -the amount o~
moisture conderlsed inside the wrapping ~teri~l.
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~7~S55
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-11
Example 2
Samples of wrapping materials, about 33 cm square
~ere taken and each sample wrapped around & block o~
10 cm x 10 cm ~ 5 cm gr~n m~ple. m e blocks o~ green map~e
were cut from a large~ block to mlnimize the variability of
moisture content from block to block. Maple was chosen
becaus~ o~ its ligh~ uniform colour and high molsture con-
tent. The wrapping material~ ~ully enveloped the map~e
block~ and were stapled thereto. The wrapped blocks were
placed about ~5 cm away ~rom a 250 watt bulb o~ a sunlamp.
Each wrapped block was e~posed to about ten cycles o~ 15
mlnute period~ of heating, with the sunlamp on, ~o}lowed by
60 minute periods o~ coolin~ with the sunlamp of~. After
completion Or the ~en cycles each wrapped block was e~posed
to six hours of natural sunlight in a w~ndow facing ~outh.
me ~mbient temperature o~ the room wa~ about 10Co Sub-
æequent to exposure to the sunlamp and sunlight the blocks
of maple were unwrapped and the amount o~ water e~ol~ed
and the extent of stainin~ were noted.
Wrapping materials "Clear", "White" and "AL" o~
Example 1 were tested. In addition two ~urther wrapping ma-
terials were included for comp~rison purposes. One wrapper~
designated "Black" compr~sed a wo~ren fabric o~ oriented tapes
made ~rom a polyethylene having a density of o.960 g/cm3 and
con~aining 2 wt.~ carbon black pigment~ in which the ~arp
tapes had a width o~ 2.5 mm and a linear den~ity of 889 dtex
and the weft tapes a width o~ 4.37 mm and a line~r density
o~ 1211 dtex, ~nd which had 3.54 ends/cm and 2.66 picks/cm,
eoated on one side wlth a 25 ~m layer o~ polyethylene havlng
a den~ity Or 0~923 g/cm3 and containing 2 wt.~ o~ carbon blac~
pigment, and coa~ed on the other slde with a 25 ~m layer of
polyethylene ha~ing ~ denslty o~ O.923 g~cm3 ~nd containing
4 wt.~ o~ a blue pigment available ~rom Ampacet Corporation
under the trade mark ~MPACET 16431.
The other wrapper, designated ~Paper~Clear~' com-
prl~ed one layer o~ 35 lb. kra~t paper~ and a layer of the
"Clear" wrapper.
The observations o~ the tests shown in Table II, are
a ~urther indication of the e~icacy of the method o~ the
present ~nvention.
1~74SS5
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~7~55
l-13 -
~ he light transmittance~ o~ ~amples o~ "Clear",
"White", "Paper/Clear"~ "Black" and IIALII wrapplng material~
were measured using a W -visible spectrophotometer.
The re~ults are shown in Table III.
Table III
~rapperTransmittance_in 400-700 nm range
Clear 82-86
White 20-50~
Paper/Clear 0%
Bl~ck 0
AL 26-29~
Five ætac~ Or planed and ~iln dried m~xed pine,
spruce and ~ir lumber, each about o.6 m x ~.2 m x 2.4 m
were packaged in a wrapping matPria}, de~ignated 'tAL-l",
8imilar to the 11Ah11 wrapper of Example 1 except that the
scrim con~truc~ion had 3.54 ends/cm and 1.26 pickæ/cm
i.e. having a warp crowdednes~ o~ 88% and a we~t crowdedne~s
o~ 54~ and the coating wa~ 25 ~m ~hick containing 2.0 wt.~ of
~la~e aluminum. Ten similar stack~ o~ lumber we~e packaged in
the '1Clear" wrapping material of Example l. All of the
stacks of lumber were wrapped directly a~ter kiln drying.
~he wrapped stacks o~ lumber were le~t in the open for
~our da~s during the month of September and on the ~i~th
day all o~ the wrapped stack~ o~ lumber were tr~nsported
on an open ~lat bed truc~ a distance o~ 950 km ~rom the
Province o~ Quebec~C~n~da, to New York Stat~, U.S,A. Upon
reachin~ the de~tination the moisture conden~tion on the
lumber wa~ checked b~ hand and ~isually. There was evidence
Or ~o~ture condensation pres~nt on ~tacks wrapped in the
"Clear" wrapping materlal~ but little or none present on
~tacks wrapped in ths "AL-l" wrapping ~aterial.
