CA1158825A - Utilisation of fibrous waste - Google Patents

Abstract

ABSTRACT

UTILISATION OF FIBROUS WASTE

A board or similar product is made from fibrous spent hops, the resin content of which sets the product. The product is preferably formed by catalysed hot-pressing.

Description

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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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 .

~~ 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 _y.
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~ 1~8825 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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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 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-~ .
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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- lo -~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 . ~ l ~ardboard Hopboard . . .. . .
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 . _ _ _ -A~erage 1.06 0.45 Standard De~iation . . __ . . - ~XAMP~ 2 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, ~"~v ."

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'` ~158825 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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!r~LE 3 .

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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Claims (7)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A board or solid product made from fibrous material compacted with a settable binder characterised in that the fibrous material consists essentially of raw hop waste which is fibrous in character and contains natural resin which provides at least part of the binder.

2. A product as claimed in claim 1 wherein the natural resin from the hop waste provides substantially all the binder.

3. A fiber board comprising compressed hop fiber bonded together with a binder comprising resin naturally occurring in the said hop fiber.

4. A process for making a fiber board which comprises pressing a fibrous material containing hop fiber which contains from about 1% to about 10% by weight of moisture and from about 3% to about 4% of a natural occurring resin under a pressure whereby the fibrous material becomes compacted into a board.

5. A process of manufacturing a product as claimed in claim 4 in which said pressing comprises a hot-pressing step wherein, prior to said step, a curing or setting catalyst is added to the hop waste.

6. A process as claimed in claim 5 wherein the catalyst is suitable for curing and setting carbonyl compounds.

7. A method as claimed in claim 6 wherein the catalyst is hexamine.