Note: Descriptions are shown in the official language in which they were submitted.
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PROCESS FOR THE PRQDUCTION OF SHAPED PARTS. A SHAPED PART ANn
A PL,A~1T FOR CARRYrNG OUT THE PROCESS
It was the primary object of the invention to provide a new
pzocess for the production of shaped parts. Within the
framework of this invention, the term "shaped parts~~ in
particular also includes panels.
Within the framework o~ the invention, it is mainly chips
and/or fibre bundles of re-growing fibrous raw materials, such
as wood (in particular annuals? and straw, that are used as the
basic material for the sniped parts. This basic material is
hEreinafter also referred to as chopped matter.
The situation prior to the invention may be described as
follows.
Chip boards and the Like are today produced largely using
liquid resiris_ zn this regard, the bonding of the chips (or
fibre bundles) used is prov~.ded by duroplastie liquid resins
based on urea, melamine and phenol formaldehyde resins or
mixtures thereof.
In addition to a limited quality development, there is,
additionally, the problem of a subsequent formaldehyde
separation. In view of the fact that the systems are
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simultaneously also aqueous systems, the moisture content of
the chips also. increases, such that it is necessary, for
example prior to a panel-pressing operation, to carry out pre-
dry~.ng which involves a high outlay in respect of energy.
Xt is for this reason, that, in certain instances, use is made
of PMDI binders to permit the bonding of difficult raw
materials without introducing any additional water.
When using straw (straw chips), the use of PMbr was, however,
irxdispensable from a practical point of view, because the wax
layer ozx the straw ruled out any other bonding means. Yet,
PMDI is not only expensive, but health risks also arise during
processing, with the result that special safaguardinr~ measures
must be taken.
From a practical point of view, in the group including liquid
resins, it is only melamine, alkali phenol resins and PMDI that
are available ~or ensuring weatherproof panels or shaped parts .
Since a rapid thorough hardening during pressing is essential.
for short pressing times, these systems are difficult to
control. The water introduced via the binding agents must
additionally be evaporated (reduction of the steam pressure),
a factor which critically affects the pressing process.
If non-flammable or not readily flammable parcels axe to be
produced, binding agents previously used in practice also reach
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the limits of >uheir efficacy, since they render the
incorporation of a fireproof~.ng agent rather difficult.
Accordingly, it was a further object of the present inventioxi
to simplify the incorporation of a fireproofing impregnation
into a chip-based or fibre-based shaped part. W this regard,
reference is made to German Patent Application 196 21 606.0,
which relates to non-flammable panels; the concepts, process
steps and technical features of a non-flammable panel, as set
out in this patent application, are at the disposal. of the
person skilled in the art when turning to the present
invention. By referring thereto, they constitute part of the
present application.
Applying the process accoxd~.ng to the invention, it is further
intended to obtain highly waterproof and exposure-fast
materials (at least V 100, in accordance with DIN 687637.
According to the invention, the objects set out above axe met
by a process for the production of shaped parts, in particular
chip and ~i.bre boards, according to which process -
- a solid duroplastic material. is added to a defibratable
basic material having a moisture content of at least 9,
preferably at least 15~ by mass,
- for the purpose of applying the binding agent, the
duroplastic material and the basic material are subjected
to a treatment in which the basic material is
simultazaeously defibxated and mixed with the duroplastic
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material, and
- the thus obtained binder-coated fibrous shaping material
is shaped to produce a shaped part.
Prior to shaping to produce a shaped part, it is possible, in
this regard, for the fibrous shaping material. also to be
subjected to a post-treatment as described hereinafter and/or
as is known to the person skilled in the art of producing
shaped parts.
In the process according to ttie invention, the basic material
used is, surprisingly, directly converted into a binder-coated
fibrous shaping material which zs designed to be pzocessed to
produce a shaped paxt without any further hinder application.
Apparently, two factors are responsible for the effects
according to the invention:
(a) the high moisture conter~t o~ tine basic material, i.e. fox'
example, of the straw chips, wood shavings ox the like,
as used, and
(b) the defibra>rior~ of the basic material in the presence of
the solid duroplastic matexial.
The results of simply mixing the basic material with the solid
duroplastic material (without defibration) are just as
unsatisfactory as is a two-step process management which
involves initially defibra>ring the basic material in the
absence of the duroplastic material, with the subsequent mixing
of the fibrous material with the duroplastic material. The
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results are unsatisfactory because, in both instances, there
is an unacceptable virtually quantitative separation of the
basic, i.e. fibrous, material from the solid bindir.~g agent,
during the processing of the basic or fibrous material/binding
agent mixture, i.e. during and after mixing of the components.
Accordingly, it is possible to conclude that ~.t is necessary
to provide the solid duroplastic material with adequate
quantities of freshly produced surface area, and this is
' provided in a convincing manner by the simultaneous operations
according to the invention. A problem of separation thus no
longer arises in the process accordiz~.g to the inven>rion.
The binding agents which are used according to the invention
and which are solid at roam temperature and are, for example,
powdery or gzanular duroplastic materials, are selected from
the following groups:
- phenol novolacs (optionally including a hardener);
particularly preferred
- epoxy novolacs (optionally including a hardener);
particularly preferred
- melamine resins
- urea resins
- polyester resins
- other duroplastic solid resins
'these resins, which, at room temperature, are solid and
virtually fxee of water, are mixed in a suitable presentation
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form (e.g. in powder form? with the basic material used, far
example straw chips or wood fibres, optionally together with
a suitable hardening agent.
It is possible for the solid binding agents used according to
>~he invention to be used, without any difficulty, together with
the known hardening accelerators, water repellents and parting
compounds, and similar processing adjuvants. It is also
possible to add graphite in order to expedite the transfer of
' heat during pressing and to simplify the rendering of the basic
material/binding agent mixture more uniform during grinding.
The resins as listed above and as used according to the
invention da not contribute any water, provided that they are
not used in the form of a dispersion, and are characterized by
an irreversible full hardening which, under the usual opex'atiz~g
conditions, is no longer susceptible to separation, and,
accordingly, they resist the most severe of extreme conditions .
Under the Conditions aGCOrding to the invention, their high
~luidity and the very good anchoring capacity, for example, on
the organic raw materials, permit the bonding even of difficult
comppnents, e.g. straw_
Additionally of importance, even when using impregnated chips
or fibre bundles as the basic maternal and, in particular,
chips which have beezz provided with a firepre~ofing
impregnation, is that there should be no interruption as far
as the bonding is concerned. This is ensurEd, in particular,
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by novolac resins which are adapted to these requirements.
Tine problem of a formaldehyde emission does not arise with the
process according to the invention.
zn the process according to the invention, the mixture of basic
material and durop7.astic material is advantageously subjected
to a drying treatment during or after the defibration
treatment, during which drying treatment the moisture content
is reduced. Since solid and at least substantially water-free
duroplastic materials are used as binding agents, a drying
treatment of this kind is carried out re J. atively inexpensively.
In the event that th~.s should still be necessary, the basic
material used is pre-crushed to the extent required, pric7r tc~
admixture of the duroplastic material.
Prior to or during the admixture of the duroplastic material,
the basic material (e-g. chips or fibres) is adjusted to a
moisture content of moxe than 15~ by mass, preferably mere than
30% by mass and, in many instances, more than 45°s by mass , The
adjusting of the moisture content is, in this regard, routinely
achieved in that the basic material is mixed with water, prior
to or during the admixture o~ the duroplastic material, or it
is treated with water vapour.
On occasion, it is advantageous when the duroplastic materials
used according to the invention are introduced into the basic
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matez~ia~ in the form of a predominantly aqueous dispersion.
It is possible for the water to contain a fireproofing
substance, for example a protective salt, for impregnating the
shaping material.
rn order to achieve particularly good results, the mixture of
duroplastic material and basic material is subjected to a
thermal treatment, preferably simultaneously with the
def ibrata.on and binder-coat~.ng treatment , during which thermal
treatment the melting temperature of the duroplastic material
is momentarily reached or exceeded. As a result hereof, a
particularly stable fixing o>e the duraplastic material on the
shaping material is achieved; it is, however, necessary to
ensure that the duroplastic material does not hardEn
pretnatuxely. It is advantageously possible for the thermal
treatment and the above-mentioned drying treatment to be
carried out simultaneously iz~ a single process step, for
example by hot air drying.
A further object of the invention is a shaped part comprising
(a) a fibrous material (such as straw fibres) and (b) a binding
agent on the basis of a duroplastic material which is solid at
room temperature,
A final object of the invention is a plant for carrying out the
process according to the invention and/or fox producing the
shaped pant according to the invention, in which plant means
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are provided for the simultaneous defibration and binder-
coating of a defibratable basic material.
Individual aspects of the invention are first explained in more
detail hereinafter with reference to examples of processes.
Example 1:
Comparison of different processes:
a) Addition of phenol novolac powder to chopped wheat straw,
depending on the fibre length and on the moisture content
(binder-coating operation without simultaneous
defibration)
wheat straw was cut in a cutter. Using the usual screexxing
means, the cut wheat straw (chopped matter including straw
chips) was divided into 5 fibre fractioz~s (main fractions)
which are defined zn Table 1 below under particulars relating
to Cl~elr fibre-length distribution.
The bulk density of each of the 5 main fractions is determined
according to DIN 1306; see the corresponding column of Table
1 below.
Each of the 5 main fractions were then divided into 3
subfractions and, in each case one of the 15 sub-fractions was
adjusted to a moisture content of 15, 30 and 50~ by mass of
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water by storage in a climatic chamber.
Each of the total of 15 subtractions was mixed in a plough-
share mixer for 8 minutes with 15~ by mass of a phenol novolae
powder (grain-size distribution: 4~), in the course of which
operation no noteworthy shortening or de~ibration of the
straw/chopped matter used took place.
Subsequently, each mixture from the respective subfraction and
the phenol novolac powder used was screened via a screen having
a mesh width of 100 ~cm, and the non-attached phenol no~rol.ac
powder was recovered. The difference between the phenol
novolac powder used and the recovered phenol novolac powder
corresponds to the quantity of added powder. On the basis
hereof, the quantity of added phenol novolac powdex added was
calculated as a percentage; see the corresponding column in
Table 1.
Table 1 shows that chopped straw matter having a shorter fibre
length takes up distinctly more powdery resin than chopped
matter having a greater fibre length. The main fraction, in
which B5~ of the fibres had a length of less than z0 mm, showEd
the best take-up behaviour at every moisture content. For
technical uses, this main fraction would still be practicable.
Chopped-matter fractions which were not examined here and which
consisted of even shorter straw particles (e.g. 95~ < 20 mm)
do not, once processed to produce a shaped part, however,
contririute appreciably to the strength of sand shaped part.
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Table 1 also shows that, within each main fraction, the take-up
propexty in respect of phenol no.rolac powdex increases with the
moisture content. The above-mentioned main fraction (85~ ~ zo
mm fibre length) at a moisture content of 50% showed the
greatest take-up capacity of all (sub-)fractions examined,
Nevertheless, in this instance, it was only 46~ of the phenol
novolac powder used that was taken up by the chopped matter,
while 54% of the duroplastic material was recovered after
screening through the 100 ~.m screen.
All the subfractions examined were, moreover, very non-
uniformly bznder-coated, i . a . the phenol riovolac powder wa& not
uniformly distributed on the chopped matter fibres used. It
appeared fzom this non-uniformity that the binder-coated
chopped matter of each individual subtraction was not
particularly suitable for further processing to produce a
shaped part,
b) Addition of phez~ol novolac powdex to chopped wheat straw
with simultaneous defibration and binder-Coating; take-
up depend~.ng on the moisture content of the basic
material
As described under a) above, wheat straw was cut in a cutter
and divided up into fractions.
A single fraction having a fibre-length distribution of 85%
< 50 mm and 26~ a 20 mm was exama.ned_ This corresponds to the
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third main fraction according to Table 1.
The fibre fraction was divided up into ~ Subfractions and one
each of these subtractions was adjusted to a moisture content
of B, 15, 30 and 50°s by mass of water, as described under a)
above, in respect of which see Table 2.
Each df the 4 subfractions was treated in a defibration mill
with 7.5°s by mass of a phenol novolac powder fc~r 8 minutes.
After passing through tl~E mill, each binder-coated subtraction
was again dried to a moisture content of ~ 6% by mass, anal the
fibre-length distribution and the bulk density were determined.
The (first) subfraction having a moisture content of $~ by mass
was, on the one hand, defibrated in a defibration mill, but,
on the other hand, a cons a.derable shortening of the fibres also
took place, such that, after passing trirough the mill, 95% of
the straw fibres had a length of less Ghan 20 mm (after an
original figure of 26~) . The bulk density of the binder-coated
fibrous matter of the first subfraction was 0_1 g per litre
(see Table 2), in comparison to 0_35 g per l~.tre in respect of
the non-binder-coated chopped matter (see Table 7.).
By recovering and weighing the phenol novolac powder (as
described under a) above), it was established that B6~ of the
powder used had been taken up on the fibrous matter.
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In an analogous manner, the subfractions having a moisture
content Qf 15, 30 and 50g by mass were also examined. It was
established that the shortening of fibres decreased
substantially commensurately with increasingly high moisture
contents, whereas the splitting of the straw particles used in
a longitudinal direction, i.e. the~.r defibration, came to the
fore. Parallel. therewith, the bulk density of the binder
coated fibre material (after passing through the mill)
decreased commensurately in the subtractions having a high
' moisture content.
The take-up property of the subtractions having a moisture
content of 25, 30 and 50~ by mass was, in each case, very good,
but the best values were achieved with the subfracrions having
a moisture content Qf 30~ by mass and 50~ by mass, in respect
of which 9B~ and 99~, respectively, of the resin used was ta7cen
up.
Summary and Evaluation:
zn comparison to the process management under a), each
individual subfractian under b) was not only mixed with the
duroplastic material, but it was simultaneously also
defibrated. This results in a surprisingly steep increase zn
the take-up capacity in respect of the duroplastic material
used, which is probably attributable to the fact tk~at fresh
surface area is made available by the defibration procedure.
thereby reducing the amount of wax-coated surface area as part
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of the total surface area available.
When comparing, for example, the binder-coated fibrous matter
according to Table 1, fourth maize fraction (40~ c 20 mm) , a
subfraction having a moisture content of 30~, with the product
according to Table 2, third subfraction (post;--milling fibre
length of 42g < 20 mm, moisture content 30~), it will be seen
that, when the process management is according to the invention
as under b), a virtually compJ.ete (~8~) take-up of the
duroplastic material used has taken place, whereas with the
process management which does not conform to the invention and
as set out under a), only 25~ of the duroplastic material is
taken up.
wzth the process management according to the invezxtxon, the
respective product was a uniformly binder-coated fibrous
shaping material, whereas a non-uniformly binder-coated product
was, in each case, obtained with a process management which
does not conform to the invention.
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Tables with respect to Examnla 1:
addition of 7.5% by mass
o~ pheno3. n.ovQ~ac powder on wheat straw
Tab~.e 1
Fibre length Bulk density gll Moisture contentResin take-up
mm (DiN 1308) .6 ga
85'~ < 100 0-5 15
1 5 .' < 20 3 0 8
850, < SO 0.4.6 . i 5 7
20 ,'o G 20 3 0 1 5
35.'e < BO o.35 15 i0 f
26,5 < 20 - 30 19
50 32
8 5 ,b c ap 0.25 --__ _ __ - 1 5 1 5
C
40 ,' < 20 3 0 z 5 I
50 38
8 S .'a < 20 0 . 13 1 5 z0
30 31 i
so ~s I
Tab ~ ° 2
Fibre lengthMoisture Past-millingPost-millingResin take-uo
content fibre lengthbulk density
mrn ,' mm 9l~
85'o c a0 8 9S~ < 20 0.1 86
2fi~~6 <
20 i5 _ ~ 70.'0 < 20 0.08 ~ 92
~
1 -
~a az~ r zo o.os gs
50 3Q~6 < 20 0.02 99
,
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Example 2:
Exemplified process : metering-zz~ of resin without impregnating
with protective salt
a) Follow-up comrninution and/or homogenizing treatment:
Pre,comminuted wood ck~ips (chopped matter/basic material)
having a moisture content of about e0s by mass are delta ezed
to a defibration mill via a metering screw at a rate of 10 t/h
absolutely dry. Along this path, 10% or 1 t/h of novolac
powder resin are added via a gravimetric meter, the batch then
being premixed.
The mill which ~.s next in line defibrates the chopped matter
and promotes the mixing of the components_ A binder-coated
fibrous shaping material is produced.
This binder-coated Fibrous shaping material ("chip/fibre resin
mixtuze") is directed, in the usual manner, to a drum-type
drier which is set at an outlet temperature of about 90° C.
The moisture content at the outlet is then still about 2s, and
the resin is caused to melt. The further cooling which then
Cakes place results in a particularly firm connection between
the fibres and the resin grains.
A next-Following scattering station produces a matting for a
panel thickness of 20 mm, with a density o~ 680 lzg/m3. This
matting is fed into a heating press, where pressing ta}ces place
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at temperatures of 220° C, at a heatinr~ rate of 10 see/mrn, with
hardening of the durop7.astie material. The panels produced are
subjected to further processing in the manner known per se.
b) Simultaneous process management:
'fhe process is carried out as under a) , but the novolac powder
resin is, in this instance, meterEd directly into the intake
zone of a correspondingly designed defibration mill.
Exemplified process: Metering-in of Resin with Protective-salt
Impregnat~.vn
a) Follow-up comminution and/or homogenizing treatment:
Bales of straw were loosened up and chopped to a length of
about 60 mm. The chopped matter (basic material), having a
moisture content of about 12~, is transported through an
impregnating screw at a rate of 6 t/h absolutely dry. rn the
intake zone of said SGrew, an aqueous fireproo~ix3.g agent is
added in an amount of 30% of protective salt as a 40°s solution,
and is mixed with the straw chips. A further metering means
ensures the conveying, via a discharge screw, of the
impregnated chopped matter to a defibration mill. Along this
route, 25~ or 900 3cg/h of novvlac powder (resin) are added and
distributed uniformly. The mixture has a moisture content o~
about 50~,
'The mill is equipped with grinding jaws and carries out the
defibration of Ghe straw ck~.ips, the uniform mixing and tha
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binder-coating operations.
The binder-coated fibzous shaping material is then passed
through an electric drier having an outlet temperature of about
75° C. Drying is carried out down to a mozsture content of
about 6%. At the same time, the novolac resin powder, which
is adjusted to these conditions, is fixed particularly firmly
on to the straw fzbres.
In a next-following scattering station, a matting is produced
for a panel thickness of 8 mm with a density of 750 }eg/m3. A
heating press Compresses the matting into panels and hardens
the resin at temperatures of 190° C, at a heating rate of 15
sec/mm. The further processing of the panels is carried in the
usual manner according to the state o~ the art.
b) Simultaneous Process Management:
Rice straw is cut to a length of about 40 mm. The chopped
matter thus obtained has a moisture content of about 8% and,
at a rate of 4 t/h, is metered into a vacuum impregnating
machine, in which it is impregnated with an aqueous 40%
f fireproof ing agent at about 25 mbar ~or at least 5 minutes .
In so doing, the take-up o~ protective salt is about 25-35~_
A metering silo, which is provided with a discharge means,
ensures that the impregnated chopped matter, which now has a
moisture content of about 40%, is delivered to a next-in.-line
defibration mill.
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In its intake region, said mill additionally comprises a
metering means for powdery resins. During the breaking-up
operation, said metering means is used for continuously
distributing a total amount o~ ~2~ of novolac resin, i.e_ 480
3cg/h, on to the straw material (chopped matter, or the fibres
resulting therefrom), Accordingly, a thorough mixing,
deEibration and binder-coating o~ the straw material take place
simultaneously in the mill.
The mill is advantageously operated using air. 'fhe air serves
to transport the raw materials (rice-straw chips/fibres, resin)
through the mill to a combined settling/filter system. In this
regard, it is preferable for hot transportation air to be used,
such that moisture is removed and, at an outlet temperature of ,
for Example, about 80° C, the resin is simultaneously fixed
particularly firmly on the fibres.
The binder-coated and dried fibrous shaping material then has
a moisture content, which is adapted for the pressing
operation, for example o~ about 8~ _ While the matting is being
produced in the scattering station, there. is no separation of
the resins and the fibres, with the result that a uniform
cross-section is obtained. Using this material, a panel is
produced to have a thickness of 30 mm and a density of 350
kg/nij. To this end, a heating press is used with a steam plate
temperature of 270° C, and a heating rate of about 20 sec/mm
is maintained.
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The panels produced are fuxther processed zn the usual mazzner .
It is possible fox panels for all spheres of application to be
produced in the manner described above. A particularly
suitable sphere is in the building sector, which has high
demands with regard to quality. panels bonded using novolac
meet all the requirements for the use thereof in humid
enviror~ments .
m the ~~ fireproof version" , they are approved as far as
building regulations are concerned, and they find further
possible application wherever high degrees of fire-resistance
are required.
A plant according to the invention is designed such that it
meets the desired process management; an adjustment of this
kind is within the expertise of the person skilled in the art,
who will, in this regard, be guided by the above exemplified
processes which may also be expanded upon,
An important aspect when designing a plant according to the
invention is that, in the simultaneous defibration and binder-
coating step according to the invention, no resin is to be lost
and, for this reason, a possibly existing suction and air-
transportation plant is advantageously designed to be a closed
circuit or a drier/circulating air unit.
Preferred embodiments of the plant according tv the invention,
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for carry~.ng out the process according to the invention, are
described in more detail hereinafter by way of example with
reference to the Figures, in which:
Figure 1 is a basic flow chart explaining preferred
embodiments of the plant according to the invention.
Figuze 2 shows a plant for the production of chip boards
(flow chart)
Figure 3 shows a plant for Che production of single-layer
panels (flow chart), comprising an apparatus for
mozstaning dry chips/fibres prior to the addition of
resin
Figure ~ shows a plant for the integrating binder-coating,
defibration and drying of shaping material (flow
Chart ) .
All, the parts of the plant, with the exception of a de~lbrating
apparatus, which is provided according to the invention, are
shown in a non-differentiated manner in the form of squares in
the );aasic flow chart according to Figure 1_ Alternative
designs of the plant acCOrding to the invention and
alternatives to the process aCCOrdW g to tkle invexltiQn are
indicated by capital letters.
In the diagrammatic illustration according to Figure 1, chopped
material (basic material) is conveyed from the left-hand side
into an apparatus 1 for moistening and/or impregnating the
chopped matter. In said apparatus, water (or an aqueous
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fireproofing solution) from a water source (or from a tank
containing fireproo~ing agent) 2 is added to said chopped
matter. In the moistening apparatus 1, the moisture content
of the chopped material is adjusted with water to more than 3o~
by mass. (Note: The chopped matter is treated with a
fireproofing solution whenever W is intended to produce
fireproofed panels. Impregnation is particularly intensive
when a vacuum impregzzating process is used, which also involves
a reduced out7.ay in respect o~ impregnatinr~ substance, in
comparison to processes carried out at normal pressure.)
Depending on the actual requirements in each individual case,
it is particularly advantageous, when adjusting appropriate
humidity cpnditions, for the moistening apparatus to be
designed such that it is possible to carry out one of the
following process steps:
- Moistening the chopped matter (as the basic material)
with water by spraying. This may be carried out in an
air cuxrent or in a spiral conveyor or in a continuous
mixer.
- Moistening o~ the chopped matter, using steam (low-
pressuxe steam), this being carried out in a manner
similar to that using water. Steam has the advantage
that it is xapidly and thoroughly dispersed in the
chapped matter, further assisting the take-up as a resu~.t
of the entra~.ned heat .
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According to an important alternative A, the chopped matter,
after moistening, is conveyed to an adding station 3 where a
solid duroplastic material from a container 4 is introduced.
The mixture comprising the moist chopped matter and the solid
duroplastic material is Conveyed from the station 3 tQ a
dafibration apparatus 5, in which the simultaneous defibration
and binder-coating treatment according to the invention is
carried out.
l~ccording to an alternative B, the solid duroplastic material
is added to the chopped matter, not in a separate adding
station 3, but already in the moistening apparatus 1. 'rhe
mixed material, comprising the chopped matter and the solid
duroplastic material, is then conveyed from the moistening
apparatus 1 to the defibration apparatus 5.
According to a further alternative C, the moistened chopped
matter and the solid duroplastic material are conveyed, either
simultaneously or in succession, to the defibration apparatus
5, where they axe then mixed. zrz this case, it is also not
necessary to provide a separate adding station 3_ Common to
all C.he designs according to alte~cnatives A, B and C is that
a permanent bonding between the shaping material, i.e. the
chopped matter which has been comminuted, for example, to
produce fibres, and the solid duroplastic material is produced
o~J.y at the stage of the de~ibration apparatus 5.
According to an alternative D, the binder-coated shaping
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material. is conveyed from tk~e defibration apparatus S into a
drying apparatus in which the moisture content of the now
binder-coated fibre material is zeduced. The binder-coated
fibre material is directed from the drying apparatus 6 to an
apparatus ~ for producing a shaping-material matting. The
matting produced in the mat-forming apparatus is finally
further processed to produce a shaped part in an apparatus S
for producing shaped parts, for example a panel-pressing
apparatus_
According to an alternative embodiment E, the drying treatment
is carzied out, not in a separate drying apparatus 6, but
already in the def~.brating apparatus 5. This then involves a
combined defibrating, binder-coating and drying apparatus.
zt is obvious that only the essential plant components and
process steps are shown in the basic flow chart according to
Figure 1. Plant components which have not been illustrated
include, for example, conveyor means, dust-extracting means,
transporters, cyc7.ones and the like.
The embodiments of a plant according to the invention as
described with reference to Figure 1 do, of course, correspond
to the corresponding variatiozls of the process according to the
invention. In a typical variation of the process according to
the invention, the introduction and addition of the powder-
res~.n binding agent, ensuring that it does not separate from
the shaping material, is carried out in the following steps
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i
which correspond to alternative A.
Step 1
The vegetable fibre raw materials (as the basic or starting
material for the shaping material) are chopped and moistened
(in SYhe moistening apparatus 1), and optionally impregnated.
Step 2
Solid powder resin (from container 4) is mixed (in the adding
station 3) in the desired mass ratio with the chopped matter
which is still moist or has, optionally, been impregnated.
(When using natural~.y dried (a~.r-dried) raw materials which are
zlot intended to be impregnated at a later stage, a ta3ce-up
promoting state is not provided fox the, for example, powdery
duroplastic material.)
Step 3
fhe pre-mixed batch thus obtained is transported from the
adding station 3 into the def~.bration apparatus 5, which may,
for example, be a special defibratic~n mill, which is used to
carry out a continuous process, and in which the chopped matter
is defibrated in the manner according to the invention, while
being coated with the duroplastic material.
Step 4_
~rhe no binder-coated fibrous moulding maternal which is
obtained according to Step 3 and is still moist (impregnated),
is dried (in the drying apparatus 6 according to alternative
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D or, according to altErnative E, still within the defibration
apparatus 5) , with the moisture requ~.red fox pressing being
adjusted and, if required, a fuxther fixing of the duroplastic
material on the shaping material being carried out.
With the process being managed in the above manner, it is
possible for subsequent working steps, such as mat formation
and pressing, to be carried out without the drawbacks described
in respect of customary processes.
It is advantageously possible for steps 2 and 3 to be carried
out simultaneously. 'this corresponds to alternative C of the
basic flow chart accordincg to Figure 1. In like manner, it is
possible fox steps 3 and 4 to be carried out simultaneously.
This corresponds to alternative E_
In a particularly economic variation, steps 2, 3 and 4 are
carried out simultaneously. This corresponds to a combination
of alternatives C and E.
when, for example, steps 2 and 3 are carried out simultaneously
according to alternative C, the take-up of the powder resin on
the shaping material is particularly promoted.
When steps 3 and 4 are carried out simultaneously according to
alternative E, a particularly good fixing of the resin on the
shaping material is achieved. In this regard, it is also
possible for step 4 to be carried out at the same time as a
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thermal treatment.
It is pvseible to achieve particularly good results when, in
order to carry out step 3 (optionally simultaneously with steps
2 and/or 4), use is made of a defibratzon apparatus which
internally screens or grades the fibrous shaping material.
coated with the duroplastic material, and which returns it to
the comminution process (grinding process) in the event that
it exceeds a specific particle size or particle length. When
the defibration apparatus 5 is designed to be an internally
screening comminution apparatus, the coated moulding material
is provided in a particularly uniform manner.
~n the plant according to the invention and as illustrated in
Figure 2, bales of straw are fed into the straw,bale shredder
51, wherE they are shredded (comminuted) and then conveyed into
a metering silo 53 by means of a carrying-chain conveyor 52.
The shredded straw is then quantitativezy transported onward
on a discharging metering screw 54, and a fireproof~.ng
impregnating solution, from a fireproofing-agent big bag 22
which is associated with a dissolving stat~.on comprising
mEtering means, is added to the straw shaping material izz the
intake zone of the impregnating screw 21, After impregnatior~,
the impregnated shaping material is transported into the
meterir~g silo 5~ (capacity: 50 m') which is provided with a
discharge screw 23_
A powdery duroplastic material (powder resin) according to the
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invention is fed from a powder-resin big bag 24 comprising a
metering station, and is added to the impregz~ated and,
accordingly, moist straw shaping material on the discharge
screw 23_ The shaping material to which the powder resa.n has
been added is then weighed Qn a roller conveyor type weighex
56, whence it is conveyed into the defibratior~ mill 25.
Defibration and binder-coating according to the invention take
place in said defibration mill.
Following on this process step, the shaping material is dried
in the current drier 26. Drying is carried out up to a
moisture content of, for example, 6~, At the same time, the
resin powder, which has been adjusted to these conditions, is
fixed on the shaping material fibres or chips.
Once discharged from the current driEr 26, the shaping maternal
is conveyed to a scattering bin 27 (w~.th discharging means)
which produces a matting from the straw shaping matezial,
depositing said matting on a shaping belt 57 comprising a gauge
S8 for measuring the mass per unit area. The matting is
transported on the belt 57 to a mat separating and suction
apparatus 59, finally reaching a press-feed~.ng belt 5o for
transporting the sirraw matting into a heating press 28 (e. g.
a single-opening press). In said heating press, the matting
is then compressed to form a panel and the duroplastic material.
is hardenEd. Finally Cafter passing through the heating
press) , the finished panels are transferred to a discharge belt
61 and, thence, on to an elevating platform 62.
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In the plant illustrated in Figure 3, shaping material bales
(e.g. bales of straw or hemp) are transported by means of a
bale conveyor into a bale breaker 63, in which they axe broken
up. From the bale breaker, the shapiz~.g material fibres or
chips are placed on a belt conveyor 64 which is allocated an
overhead magnet 65. 'rhe shaping material is conveyed from the
belt conveyor into an impact hammer mill 66, in which a pre-
commiz~utlon of the fibres or chips of the rhapz.ng material
takes place.
In a next-in-line moistening apparatus 31, a desired moisture
content of the shaping material is adjusted; in this regard,
it is possible for moistening to be provided, for example, by
means of spraying water or by means of water vapour.
An, alr~transportation apparatus transports the moistened
comminuted shaping material to a si7.o housing 6~ which is
allocated a discharging apparatus 68 comprising a metering
screw. The shaping material arrives in a detibrating machine
35b, e.g. an ultrafibrator or refiner, via a meterixxg chute.
zn said defibrating machine, (pre-) defibration takes place.
An aiz-transportation apparatus then transports the shaping
material into a suspension drier 36 which comprises a control
means and a gas surface burner, and in which, if required,
drying of the shaping material takes place to a desired
mO~.sture Content.
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The shaping material is transported from the suspension drier
36, which provides additional screenir~g, to a revers~.ng screw
69 which, in the event of a ~zre, is opezated in a direction
opposite to the usual conveying direction, in order to isolate
any burning matter transported from the further parts of the
plant. ~rhe shaping material then passes through a screening
machine 70,
Via a further air-transportation apparatus, the shaping
material then arrives in a silo housing 71 which is allocated
a d~.sGharging apparatus 72 comprising a metering screw and,
next in line, a conveyor-type weigher ~3, whence the shaping
material arrives in a second defibrating machzne 35a, in which
it is uniformly mixed with a duroplastic matez~ial according to
the invention, said duroplastic material being injected fzom
a binder-preparing and metezing apparatus 34.
According to an important alternative design of the plant, the
following plant components are omitted_ conveyor-type weigher
73, second defibrating machine 35a and binder-preparing and
me>rering apparatus 34. The duroplastio material is then
admixed in the form of a dispersion in the moistening
apparatus, while the de~ibration and binder-coating according
to the invention take place in the defibration machine 35b.
'The shaping material which is coated with the duroplastic
material in the manner as set out by the invention, is conveyed
by means of a troughed belt conveyor Qr an air-transportation
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apparatus (as an alternative to the belt conveyor) to a
scattering bin 37 which is provided witk~ a shaping head ~or
farming a matting.
The bindex-containing shaping material is discharged from the
shaping head in the form of a matting and is moved onward
between scattering walls on a shaping belt 74 with a chain
conveyor and a press-allocation chain conveyor; in this
regard, the shap~.ng belt is allocated a mass per unit area
gauge for controlling the scattering bin. A transverse-cutting
saw (z10 mm) 75, comprising a catchir~.g means, cuts the matting
to the size desired, and a metal detector arxanged behind said
saw detects any metal contamination which may be present in the
matting. If metal is detected, a faulty-scattering device 75
which co-operates with a suction apparatus, removes the Flawed
matting.
The mats are subsequently directed to a press~.ng appax-atus 38,
in front of which, however, a surface-spraying device 77 is
arranged For spraying watex ox parting compounds on to the
mats. Paxlels according to the invention are produced in the
pressing apparatus . Th.e usual apparatus for ~ur>rher treatments
are connected after the pressing apparatus , in respect of which
see also Figuxe 2.
In the plant for the integrated binder-coatzng, detibration and
drying of shapzng material as illustrated in Figure 4, a spiral
conveyor ~B for pre-comminuted shaping material (for example
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pre-comminuted straw) is illustrated, said conveyor
transporting said shaping material to a dust screen 79, whexe
dust is largely removed Ezom the shaping material.
'The pre-commznuted shaping material is then quantitatively
transported onward on an impregnating screw 41, and a
fireproofing impregnating solution, Pram a metering station 42
cahich is allocated a dissolving station with metering means,
is added to the shaping material. in the intake zone of the
impregnating straw 43.. Impregnation takes place Qn the
impregnating screw at a reduced pressure of, for example, 25
mbar. After impregnation, the impregnated shaping material is
t~canspozted into the metering silo 80-
On a next~fo~.l.owing roller conveyor-type weigher 81, the
shaping material is weighed and then transported into an ultra-
rotor defibration mill 45 comprising an integrated screening
device, a metering screw 82 and a hot air apparatus 83 (for
drying and for thermal treatment). At the same time as the
shaping maternal is charged into the defibration mill 45,
powder resin from a meterir~g station 44 is introduced via a
metering screw 82 into the de~~.bration mill. Means 84 are
provided to ensure that the quantity of shaping material
charged into the mill per unit of time and the quantity of
powder resin introduced are in ~. substantially predetermined
ratio to each other. rt is, ~or e~cample, possible for the
weighing signal of the roller conveyor-type weigher 81 to be
used as a reference signal for determining the quantity of
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powder resin which is to be introduced from the powder-resin
metering station 44 via the metering screw 82 and into the
defibration mill 45_
In the defibration mill 45, the shaping material is
simultaneously defibrated, coated with powder resin and dried.
Drying is carried out by means of through-~lowing hot air which
is produced, for example, zz~. a radiator 29 and injected into
the mill from below.
The mill 45 comprises means fox screening or grading the
shaping material (in its binder-coated or non-coated state)
contained therein. Coarse particles are screened out in the
head of the machine and are recycled for grinding in a
downstream intake region. In this way, it is also possible for
knots in stalks and the like to be loosened, axed for this
reason iG is also possible to dispense with a separate
downstream screening device.
The ~~nally binder-coated and dried shaping material fibres are
transported into a separator 85 for dry fibres, whence they
ultimately arrive in a metering silo (scattering bin) 47, where
matting is produced from the binder-coated shaping mar.erial,
~or example by means of an associated scattering apparatus.
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