Note: Descriptions are shown in the official language in which they were submitted.
1 15882~
DESCRIPTI0~
~he present i~vention relates to the utilisation
of fibrous waste and in particular to the production ;~
of hoards and similar products from fibrous waste
material.
In recent ~ears much of the timber previousl~
used for construction and general domestic purposes,
such as furniture making, has been replaced b~ manu-
ractured materials such as hardboard and chipboard.
These ma~ufactured materials, although originally
10 produced to use up waste wood left over from saw- ;
mill operations, are now used on such an extensi~e
scale that substantial quantities of ~aluable timber
are rendered directly into wood chips and fibres for
their productio~.
A ~ew waste fibre ~oard has now beer discovered,
utilisi~ a true waste material which i8 particularly
suitable for compaction i~to boards and similar
produots.
In accordance with the present invention boards
or similar products co~prise compacted hop fibre
waste. Ge erally it is envisa~ed that the products
of the present inve~icn co~prise hop liore waste æs
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---` ` 115882S
their major, if not only, fibre component. ~he
invention also includes processes in which material
comprising hop fibre waste is compacted to give boards
~nd s;m;lar products.
~he use of hops in the manufacture of beer is
well known and hop waste is a~ailable as a by-
product from breweries and hop processors. Hop
waste is typically fibrous in nature and may initially
contain a high proportion of wæter, often up to
about ~/c by weight or more of water. Usually,
therefore, it is desirable to remove excess moisture
from the hop waste before compaction, for instance
by centrifuging and subseauent dr~ing e.g. at
elevated temperature. ~referably the water content
1~ of the hop waste is decrePsed to less than about 5~iO
or especially less than about 1~o e.g. about ~i,
by weight before compaction. It ~ill be appreciated,
however, that the hop waste should not be overdried
as this may give rise to undesirably brittle products
on compaction, and thus preferably the hop waste con-
tains a~ least about 15~ by weight of water.
The hop waste may be mixed with suitable resins
or ~her binders prior to com~action, and such resins
~nd binders include those used in the pro~uction of ~`
hardboarà, chipboa~d æna s-mllar products and are
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~~ 1 15~3825
usually added ~n similar proportions. I~ accor-
dance with the present invention, however, it
has been discovered that the natural resin present
i~ the hop fibre material may be used to provide
a binding agent for compacted products. Solve~t
extraction techniques have revealed that the hop
fibre wzste contains from about 3 to 4%~ on dry
weight, of resin, Pnd thus adv~ntageously the hop
fibre waste may provide ~ll the binding agent re-
quired for compaction.
~ hus in a preferred embodiment the products ofthe present invention comprise compacted hop fibre
waste in which the binding agent is provided by
natur~ resin originally present in the waste.
Generally, otherwise, other additives such as
preservatives, fire-proofing agents, water repellAnts
and seala~ts, may be added to the hop waste as
desired. In addition the hop waste ma~ be subjected
to other preparation besides removal of water, such
as sterilisation.
~ he hop waste may be cold-pressed to give
the products of the inventio~, for instance when a
suitable cold-set~ing resin or binding agent has
been added. ~iore usuz~ , ho~iever, the hop waste is
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~ 1~8825
-- 5 --
compacted by a hot pressing technique. Pres~ures
used, both for hot and cold pressing, ma~ vary
widely, for instance from a few hu~dred e.g. about
100, up to a few thousand e.g. about 3,000 psi, de-
pendent upon the density reauired for the products.Generally, for hot-pressing tech~iques, pressures
of greater than about 300 psi, preferably greater
than about 500 psi, especially about 850 psi have
been found to be satisfactory for production of
hardboard like products. Higher pressures, for
instance from about 1000 up to 2000 psi or more
e.g. about 2400 psi, however, generally give rise
to stronger and more compact products. ~he equip-
ment Pnd tech~ioues employea for compaction of hop
waste are generall~ similar to those employed for
the production of other compacted waste fibre products.
Generally the hop fibre waste is hot pressed
at temperatures of greater than about 100C for
periods of up to about 20 mi~utes, though excessively
elevated temperature e.g. over about 180C may
lead to undesirable charing. Preferably hot pres-
sing is carried out at temperatures from about 150C
up to about 170C for from about 3 up to about 7
minutes.
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- I 15882
-- 6 --
In accordance with the invention, it has
also been discovered that addition of suitable
catslysts to the hop waste, before hot pressing,
enh~nce the binding properties Or the natural
resin present therein. ~he natural hop resin
typically contains carbonyl compounds, and it is
believed that catalysts for the curing and sett m g
of such compounds are particularl~ suitable for
use in the present invention. In practice it has
been found that hexamine (hexameth~lene tetr~m;ne)
is highly satisfactory as a catalytic additive for
the hot pressing of hop fibre waste, and may con-
venientl~ be introduced to the waste as a solution,
for instz~ce in water or alcohol, using preferabl~
about 2g Or solid catalyst per 100g of waste (dr~
weight). ~he use of a catalyst may be detectable
in the compacted products, and generally leads to
increased strength properties as compared with un-
oatalysed products, for ins~ance strength increase
of 7~fi or more. Advantageously the catal~sed hot
pressed products of tne present in~ention may ex-
hibit strength properties com~arable with hardboard.
~ he procucts of vne presen- invention m~y be
produced in an~ appro?riate form, such as boards,
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- :`` I 1 58825
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sheets, blocks, or beams including those forms in
which hardboards, chipboards and other similar
waste fibre boards are produced. Particularly
advantageously, however, hop fibre waste exhibits
plastic-like properties on hot pres~ing and thus in
a preferred embodiment products may be produced in
a moulded form. Such moulded products may conven-
iently be tailor-made for the furniture industr~.
For instance, boards may be produced with pre-
moulded ru~ners~for drawers, or in a pre-moulded
form to facilltate jointing of boards, or with
moulded relieved design on their surfaces. An
example of such a moulded product in the form of a
board having elongate parallel ridges moulded into
one or both of its surfaces, for instance with
elongate ridges moulded into both surfaces, the
ridges mutually perpendicular.
Generall~ also the hop fibre board of the inven-
~` ~ tion ma~ have surface treatments applied for decor-
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ative or other purposes. ~or example materials
` such as waste laather, or drled leaves may be applied
to the surface of the hop board during hot pressin6
; or otherwise ~d may provide a highly desirable
~ ~ decorati~e finish.
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" I 1588~5
The invention is further illustrated in the
following non-limiting examples which relate to the
production of hop fibre boards by hot pressing
tech~i~ueæ.
EXAMPLE 1 Uncatal~sed ho~ fibre board.
Raw spent hops are obtained from a brewery
(Guinness Park Royal) and initially contain about
86% moisture. 5~/O~:of the water is then removed by
centrifuging at 2000 rpm in An 8" diameter
Broadbent basket centrifuge, and the hop waste is
further dried on trays in an oven at 80& to about
~% water content.
~bout 200g samples of the dried hop waste with- `-
out any additional resin are then compressed to 4 mm
: 15 thickness boards in a 250 mm square heav~ steel box
tool under 6 dlfferent hot pressin~ regimes. mhe
: quantity of waste used in each case, is chosen 80 .:
as to yield a 4 mm thickness board under the various
.,}~ .. hot. pressing ¢onditions employed. 4 mm x 12.7 mm
20 ~.~sa~p1es of each board are tken tested for cross-
:. ~ .brea~ing strength on 2n Instron machine housed in an
:~ ~ air-conditioned room at 5~c RH and 23C. The
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Instro~ machine is set with the dista~ce between
the outer supports of the ~-point loa~ing system
38.1 mm apart, with cross-head spaced 25.4 mm/
minute ~nd full scale ra~ge set to 0-100 lbf. ~he
results obtainied are giYen i~ ~able 1 below and
are comparative with results of about 67 lbf. and
about 51 lbf. obtained simila~ly for plywood a~d
hardboard respectively.
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15~82S
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~hBLE 1
Cross-breakinl~ stren~th in lbf. o~ 4 mm hoP-board
made under 6 diffe~in~ hot ~res~in~ re~im~s.
_ . . . ,
150C 850 psi 160C 20 minutes
_ _ ~ P~SURE
8 ~;ns. 15 mins. 30 mins. 400 psi 700 p8i 850 psi
. . ...
14.5 lbf. 17 24 18 20.5 28
13.5 23.5 13 24.5 22.5
13.5 18.5 21.5 23 20 28
16.5 15.5 18 21.5 17 26.5
13.5 21.5 21 21 15.5 30.5
13 21 23 24.5 23.5 14.5
12.5 12.5 19.5 20 19.5 19
23 12 24.5 23.5 20 20.5
14.5 11.5 17 17 25.5 19.5
13 17 25.5 25.5 1~.5 27.5
18 18.5 22.5 20.5 21 20.5
21 18 19 25 20.5 23.5
19 13 24.5 17.5 18.5 28
17 26.5 16 17.5 17
.
A~erage
16.93 16.18 22.14 20.43 20.14 23.25
Standard De~.
_ 3.14 2.80 3.60 2.74 4.72
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12.7 x 4 x 40 mm samples of a hop-board pre-
pared above (850 psi, 160C, 20 minutes) are tested
for impact strength using a modified ver~ion of the
Izod machine, working edgewise on to the samples
which are left un-notched. ~he results obtained
are given In Table 2 as Joules per 12.7 mm, ~nd
which includes results obta;ned similarly for a
hardboard.
~ BL~ 2
Im~act stren~th in ,ioules ~er 12.7 mm for 12.7 x 4 x 40
mm ho~-board (850 ~si, 160C 20 mins) and h~rdboard
sam~les.
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-- l 158825
- 12 - -
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~ardboard Hopboard
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0.76~ 0.307
1.213 0.307
0.914 0.460
1.801 . 0.460
1.362 -307
1.213 0.763
1.064 0.307
1.213 0.914
0.763 0.460
1.064 0.460
1.36 0.612
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A~erage
1.06 0.45
Standard De~iation
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Similarly to ~xample 1, a 4 mm board is prepared
`~ from dried hop fibre waste except that rior to co~-
paction the hop fibre is treated with catalyst solu- -
tion (8g of hexamine to each 100g of dried waste,
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- 13 -
added as a solutio~ of 10g of hexamine per 100 ml
of alcohol). Hot pressing is carried out at 150C
at a pressure of 750 psi for 10 m;nutes and also a~
uncatalysed board is similarly prepared.
4 x 12.7 mm samples of each board are then
tested for cross breaking strength on an Instron
machine as in Example ~ except that the dista~ce be-
tween the supports is increased to 50.8 mm and the
loading rate decreased to 2.54 mm/minute. ~he re-
sults obtained are given in Table 3 and clearly show
that the cross brea~ing strength o~ the catal~sed
board is more tha~ doubled with respect to the un-
catalysed board and is approximately the same as
wou1d be expected for a herdboerd.
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1 1 58825
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!r~LE 3
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Cross-brea~in~ stren~th in lbf of catal:~sed ho~board
aæ co~pared with uDcatal:~sed ho~board.
Uncatalysed Catalyæed : :
,
11~5 29~9
11~5 27~6
10~5 21~7
9~9 25~4
9~5 23~4
11~5 21~9
13~5 ~ 22~5
11.0 17~0
Mean
11~1 23~7
S.D. .
1~23 ~ 3~97 ;
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