Note: Descriptions are shown in the official language in which they were submitted.
3 ~791~
This invention relates to a method of an apparatus for
~a~ing containers, container blanks or other similar objects.
In the fruit and veegtable industry it is normal to
use wooden or corrugated carboard crates for packaging and
transport. Although these are non-returnable they are never-
theless expensive to produce and it is an object of the pre-
sent invention to replace crates such as these with containers
made from cheaper materials such as surplus ma-terials.
The present invention in accordance with one aspect
provides a method of making articles from raw fibrous mate-
rials comprising the steps of providing fibrous material in
raw, unchopped or only coarsely chopped conditions , admixing
the raw fibrous material and a thermal setting bonding
agent, substantially simultaneously compressing the raw
fibrous material/thermal setting bonding agent admixture
while heating the same to cure and set the thermal se-tting
bonding agent while essentially retaining the raw characte-
ristics of the fibrous material, and the heating being conducted
at a temperature range suEficient to maintain the raw
characteristics of the fibrous material while essentially
avoiding schorching thereof.
According to this aspect of the present invention
a method for making articles, e.g. containers, container
blanks or o-ther similar objects may comprise mixing straw
or other raw fibrous material (hereinafter referred -to as
straw for convenience) with a thermal setting or heat
curable bonding agent, compressing the resultant mixture
and applying heat to commence curing of the bonding agent
to produce a container, container blank or other similar object.
Preferably the straw is either unchopped or it is
only coarsely chopped. This arrangement allows variable
lengths of straw to be used which are arranged in random
directions to provide good cross bonding so that material
has good flexibility and also rigidity.
The weight proportions of bonding agent to straw
., - - - . . . .
1 179 ~ 0 8
are preferably approximately 89~ straw to 11% bonding agent,
although these proportions may ~ary by up to 2% in either di-
rection.
The bonding agent may comprise 90.225 parts by weight
formaldehyde, 40 parts by weight isocyanate, and 8 parts by
weight hardener per 1000 parts by weight straw; it may
include 12.5 parts by weight of water per 1000 parts by weight
straw.
The straw and the bonding agent are conveniently
mixed in a mixer, the bonding agent being supplied in
liquid form to the mixer, in such a way as to apply an
event coating of the straw as for example by way of a spray.
The pressure applied to the resultant mixture
is in the order of 80 tons per square metre, and the heat
is preferably applied at a temperature of 150 centigrade
and at this temperature the heat is applied for - \
. . ~ \
~ ~9 ~ ~
20 seconds for each millimetre of board thickness. The temperature
of 150 centrigrade has been found to be the optimum but lower
temperatures do~l to 135 centrigrade can be used, curing taking
correspondingly longer, and also higller temperatures up to 175
centrigrade can also be used but in this case care has to be taken to
avoid scorching.
Conveniently a lining material is applied to the container
or container blank or other similar pro(l;lct, and this may be applied
eithcr cluring molding oC subsctlucntly. Ihe lining material may be
pal)cr or pl.lstics shcct.
In the case of a container blank it may be provided with marking
or creases where it is to be folded, and in this case provision may
al90 be made for stacking lugs, thickencd end walls, hand grips,
ventillation holes and other suitable provisions for use with
contaillcrs .
- According to another aspect of the present invention a
container or the container blank or other ~iimilar product is made by
the method as set forth.
According to a further aspect of the present in~/ention is a
container of container blank or other similar product made from
straw or othcr raw ribrous m.ltcri~l.
According to a further aspect of the present invention apparatus
for r~aking artic1es,e.g.corltairlers,con-ta1ner blanks or other simil~r objec-ts fro~
straw comprises means for mixing straw with a heat curable bonding
agent, means Lor compressing the mixture in a mould and applying
hcat to conmlcncc curing Or tllc bolldinu aucllt, and subsequently rcmov-
ing the formed container, container blank or othcr similar product
~rom the mould.
lhe invelltioll may bc IcrforD-ed in various ways and o~ specific
h
' '` .
1 1~9~
embodiment will now be described by way of example with reference to
the accompanying drawings in which:
~ ig. ] is all illustra~ioll of a siclc o[ a container (w;th the
lining removed) showing how a straw is arranged in a random manner
and
Fig. 2 is a graph of board thickness againstingredients.
In the invention, straw, normally in bale form~ is supplied to
a straw chopper whcre it is coarsely chopped with the aid of a chaff cutter
for conven-ient handling. It is not in fact essential to effect this
chopping but it tencls to assist in handling. Ilowever, it is prefer-
able to have a considerable quantity of variable lengths of straw,
for example as long as 250 millimetres down to 10 millimeters or even
less so that in the finished product the individual lengths are
arranged in random directions to provide good cross bonding which
gives strength and rcsistance to bending whilst at the same time enabling
a degree of flexibility. ~n example of the finished product is shown
in figure 1. This shows the side view of a panel for a container in
which straw as such is used and it can le secn from this that the straw
is of very consiclcr;lblc variation i.n lcngtll an(l is arran~ed in totally
random directions to give the cross-bonding effect referred to. It
will be appreciated that in the finished product a lining of paper
would normally be placed over the straw which would thus be invisible.
The straw then passes from the straw chopper to a mixer where
it is mixed with a bonding agent. This is effected by having means
in a mixer for applying an even coating of resin mix on the straw as
by a spray in liquîd form and an automatic metering device which is
preset according to the quantity required. The bonding agent is a
fomaldehyde, isocyanate and a hardener possibly with water added to
reduce ~iscosity. It has been found that the proportions of 89% straw
t 1~10~
to 11% bonding agent, with plu9 or minus 1-2%, the proportions being
by weigllt form a suitable mixture. The straw and bonding agent mix-
ture is led from the mixer into a press. The press may be in the
form of a mould being the final shape of the container to be manufact~
ured or alternatively may be in the form of a mould onl~ for making a
flat sheet for subsequently forming container bLanks, or in a shape
suitable for other similar articles. Ileat is then supplied to the
press to start the curing process and in this heating period approxi-
mately 90% of the curing takes place, the remaining 10% ocurring during
the subsequent co~ling.
In the case of the blank, creases or marking lines or other
indentations are pr~vided during the moulding where the blank is to
e folded. In this form the blank can be stored until required for use.
into
A blank may be made up / a carton at any time. This is effected by
taking the blank, bending the sides at the nppropriate creases and
sccuring tl-c s;dcs togctllcr as by stapling or gluing. Altcrnativcly
a carton can be produced by securing together sheets of preformed
material which may be for example in the sllape as shown in figure 1
and these sheets can be secured similarly by stapling or gluing.
Also during tl~e moulding process features such as staclting lugs,
tl~ckened end walls, hand grips, ventillation holes and the like can be
formed.
With the present invention it is thus possible to utilise either
on site or in a factory supplied locally a surplus product such as
str;lw [or making into a contailler or containcr blallks and for example
on a farm which produces ceral and fruit crops surplusrom the cereal
crop can easily be converted into blanks, but the methods set forth
above, the blanks stored until such time as the containers are needed
and the blanlts then made into containers for packing the crops. ~s
I 1~910~ '
thc raw matcri;ll is in abull(lallt suplly tl~c cxpenscs arc thus kcpt
down to a minimum particularly by using local farm labour when it is
not rcquircd for other purposes.
It has bccn found for cxample that a convenienentpressure
for use in tbc press is 240 tonncs for a thrce square metre sheet i.e.
a pressurc of 80 tonnes per metre for a board of25.4 oml tllick.
Rcfcrencc is now madc to figuTc 2 which is a graph and where it
will bc scen that thc X co-ordillate rcprcscnts board thickness in milli-
mctrcs all(l tl)c Y co-ordill;3tc gr;lmrllcs o[ s~r;lw (x 100) pcr rcsin mix
and the resin mix itself and which has been found to provide the best
rcsults is ma-lc from fomal-lcllydc in thc quantity of 90.225 grammes,
i~O~`y311;1~ ,n ul~ s~ ll;lr~ !r 8 ~-r.~ , w.~ r l2.r~ ~r~ s (tl~c
water being optional but being used to reduce viscosity). As can be
~SCCIl LrOIll the grapll it i5 possible to obtain soft lightweigllt board,
~ood standard bo~rd~ or hard dcnsc boar(l according to tllc qll~ntity
of straw per resin mix. In ~act in the example the quantities are
based on a board l~aving an area of 5,000 sq centimetres. Thus for
ex~ml)lc it will bc sccn from th(~ graph that if a liglltwe;gllt board is
required at 14 millimetres thickness, then only 2,800 grammes of straw
l r~ ill lllix ;ll~ l;r~l lol ;1 Illlil ~l 5,()()~ r(- ~l-lltiol(~trcs.
Ilowcver, ;f a har(l dense board i.s requirc(l thcn 3,880 grammes of the
straw rcsin olix ;Irc rc(luirc(l ~or ~hc sam(! thickllcs~s of 14 nml board.
