Note: Descriptions are shown in the official language in which they were submitted.
7 ~ 9
The ~nverltion relates to ~ fibre mat f~r producing
a three-dimension~lly, moulded moulding by the dry proces~.
It IS known to produce three-dimensionally moulded
mouldings ~xom lignocellulose fibrous materials by loosely
sprinkling onto an endless con~eyor belt the fibres ~etted
with small binder quantities, levelling the height of the
fibre layer a~plied by a pairing roller and subsequently
prestrengthening the ~ibre lay~er between pairs of rollers.
This leads to a sheet-like endless extrudate which can be
cut into individual sheets from which flat blanks arQ pro-
duced following Intermediate transport. Following vapour
coating of the blanks, they are placed in a compression mould
and are moulded into the final moulded articles, accompanied
by the curing of the binder (DAS 1,224,949). The individual
sheets cut in this way initially have a low deformability
and limited breaking strength. Following the vapour cGating
necessary for increasing the deformabllit~ for producing the
three-dimensionally moulded moulding articles, the sheets no
longer have a significant internal cohesion and must therefore
be very carefully treated and transported. Due to their
limited fibre cohesion in the steam-treated state, they
can only be further shaped to a limited extent without there
being thinning of the material areas tensile stressed during
moulding, with the loss of fib~e cohesion and the tearing
~ of the mat.
..~'
:xi
116~77g
To obviate this pxoble~, it is known (DOS 1,453,
4161 to apply to the fihre mat a reinforcing fa~ric ~hich can
be deformed ~ stretching and which is pressed into the
fibre la~ex ~y the rollers used for prestrengthening the mat.
Here aga~n, the bond between the reinforcing fabric and
the fi~re mat ~s largely lost ~hrough the vapour treatment
necessary prior to the final shaping. Thus, during the
moulding process necessarily considera~le relative movements
occur between the individual fibres, which can bring about
the tearing o~ the fibre mat.
GerrQan patent 2,364,025, also discloses a fibre
mat comprising two lignocellulose fibrous layers between
which is placed in f~rmly adhering manner a supporting layer~
The pre-moulded fibre mat has a plurality of regularly dis-
tributed zones of limited cross-section. This improves the
adhesion of the supporting layer during vapour treatment,
~o that the tensile stresses occurring during moulding can
be better distri~uted in the mat. In addition, such a mat
extrudate can be wound onto a reel following prestrengthening,
which facilitates handling and transportation.
In order to permit the manufacture of particularly
thin-walled, three-dimensional moulded mouldings, such as
are for example ~e~ulxed for the internal lining of motor
vehicle intexiors, a process ~s used (German Patent 2,338,
650~ ln which the fibre mat is gradually moulded in a mould
e~uipped ~ith a plurality ~f foxce plugs which can be
1 16~7~9
operat~d in tim~ se~uence. T~is gradual Inoulding i~ necessary
to prevent tearIng of the f~b~e mat. In this process, the
fibre mat ~s gradu~ fed to the deformation points without
there being an~ tearing af the fibreS. This known process used
in the three-d~mensional shap~n~ of thin-walled mouldings re-
quires especially careful application due to the sensitivity
of the fibre mats and also re~uires a large amount of time due
to the gradual, successive ~oulding.
~ further disadvantage of the known process is that
the fibre mats mustbe made from top-quality wood fibre mat-
erials if they are to have satisfactory deformation character-
istics, particularly in connection with the necessary small
wall thickness of the mouldings. It is impossible to pass
below a lower fibre length limit if the tearing of the fibre
mat is to be avoided during deformation. It is therefore
impossible to use shorter fibres, such as are for example ob-
tained in the preparation of waste materials, for example
waste paper, although said waste materials have completely
satisfactory material characteristics, particularly in the
case of the admixture of longer length fibres.
The problem of the invention is to obviate the
disadvantages inherent in the known fibre mats and their
processin~ processes in such a way that a fibre mat is obtained
which, in the manner of a deep drawing process, can be im-
mediately moulded to a thin-walled moulding without the hitherto
necessar~
3Q
7 7 9
gradual moulding procedure. Furthermore, through the addition of
short-fibre waste material a higher strength, smaller wall thick-
ness moulded article can be obtained.
According to the present invention there is provided a
fibre mat for producing three-dimensionally moulded mouldings,
by means of the dry process, comprising a prestrengthened layer
containing cellulose or lignocellulose fibres and deformable sup-
porting layers with which the fibrous layer is joined, character-
ized in that the fibrous layer is arranged as the central layer
between two supporting layers and that the supporting layers
comprise creped low-extension or extension-proof foil materials
joined to the central layer surfaces, whilst maintaining the pull-
ing out properties of the creping.
The term "creping" is understood to mean all shapi~g
processes to the supporting layer which increase the surface area
thereof without stretching or extending the actual material when
it is pulled out in at least one direction. Such shapes can be
in the form of parallel folds such as pleats and this is advanta-
geous if a substantially groove-likel three-dimensional shaping
is desired. In the case of cup-shaped shaping crossing folds
are recommended. The term "creping" also covers, for example,
circular folds or impressions and in the case of fabrics those
yarns which are crimped or overtwisted.
The advantage of the rnats according to the invention is
initially that the fibre layer no longer comes into contact with
the mould members. Thus, the sliding characteristics of the mats
according to the invention during moulding are improved in the
same way as the separation characteristics ater moulding. This
improves the surface properties of the finished parts. In addi-
tion, during the mould closing process,
~a 4 _
1 ~6~779
the flb~au~ la~er can be thexmall~ insulated from the mouldSurface$~ so th~t there is n~ premature curing of the fibrous
layer Sur~aces. This improveS the strength characteristics
of the fibxous layer.
The two-side~ covering o~ the fibrous layer with
supporting layers increases the effective interface between
the fibxous layer and the supporting layer. This in itself
considerabl~ improves the reaction of the favourable
defoxmation behav~our of the $uppoxting layers on the fibrous
layer. An additional important advantage is provided in this
connection by the creping of the supporting layers according
to the invention. The prior art, elastically defonEble sup-
porting layers, can be extended up to failure, i.e. they
cover the surface requirement necessary for three-dimensional
deformation and become thin during déformation. Within
the scope of their elasticity, they are initially randomly
extensible, the extension being distributed in an uncontrolled
manner over tne entire surface area. Since it is necessary
to avoid in the fibrous material local extensions which are
greater than the covering or overlapping length of the fibres,
the cooperation between the prior art elastic supporting layers
and the fibxous layer means that locally the extensibility
of the fibrous layer can be exhausted. This considerably
reduces the possibility of shaping fibre mats with supporting
layers according to the prior art. ~s opposed to this, creped
suppoXting la~ers have the suxface reserye neceSsary fox
; shaping ~ithin the actual cxep~ng and need not cover it by
a thickne~s. 1QSS. ~f the $urface xe$e~Ye of the creping i$
locall~ u~ed up~ te~sile st~es~es ~re ~uh~e~uentl~v txansfexxed.
~nto the adjacent area$ and their surfacç reserye is also
utilized, The shape and ~nten$~ty of the creping can be selected
in the way that the local extensibility necessary for shaping
- 5 ~
1 16~77g
is ensux~d a,nd the l~c~l extensibility of the sU~po~ting la,~ex
can be ~d~pted to the cavering length of the fibres.
This prevents a local failure of the fibrous layer.
The laxge ~uxface area of the ~upporting layers in the creped
state also a~dS the force transfex to the interface between the
fibrous layer and the supporting layer. Thus, a mat is formed
which is able during deformation to transfer significant tensile
stresses, even in the outer area, without the local failure
of the fi~rous la~er.
The reduction of the stretching proportion in the
overall mat deformation means a more uniform thickness distri-
bution in the finished article. This gives the particularly
advantageous , possi~ility of producing members, whose wall
thickness is much less than that of ~he hitherto produced
members. In the prior art, a finished article thickness of
approximately 2mm is considered to be the lower limit of what
~' is technically possible. By means of the mats according to the
invention, it is possible to produce finished products with a
satisfactory quality and wall thickness of only approximately
lmm.
As the increase in the surface area of creped
supporting layers only requires forces during moulding, it is
possible to use higher strength supporting layers for the mats
according to the invention. The moulded article then has a
sandwich structure comprising a medium-strength core and high-
strength coVexing layers. Th,e xesultin~ improVement to the
stxength a,nd xigid~ty of the fini~shed pxoducts makes it pOS-
sible to pxQduce the latter with thinner w~lls and thexefoxe
moxe ady~ta~geously~ fxo~ the mater;~al and cost standpoint than
3Q in t~e pri~or art, wh~lst pxo~d~ng the ~same use cha~acter,istics.
; The.'twQ-sided covexing of the fibre mat with closed
suppoXt~ng laxers also reduces the risk of damage to the mats
- 6 -
'7 7 9
dur~ng t~nsport~tion ~nd handlin~.
ThiS is p~rticularl~ important if thin-walled finished
articles axe sought, so that the fibxe mats have only a limited
thickness and consequentl~ l~mited inherent stability. The
two-sided suppoxting layer ~n particular considerably reduces
the ~racture risk of thin fibre mats during transporta-
~ion.
The advantageous possibility of reaucing by about a
half the wall thickness of the ~inished articles through the
use of the mats according to the invention will now be de-
scribed aga;n ~n general terms.
Quite apart from the weight and material saving of
50% the necessary overall moulding time is reduced to approx-
imately half. The moulding time when moulding wood fibre mat-
erials is mainly due to the inadequate thermal conductivity
of this material group. A thickness reduction means a cor-
respondingly faster thorough heating (in practice this means
fixed moulding times/millimetre of material). This makes it
possible to increase the utilization rate of the investment-in-
tensive large compression presses and can be increased in thesame porportion as the number of necessary cost-intensive moulds
can be reduced. Thus, considerable rationalization can be ob-
tained with the mats according to the invention.
The punctiform or linear, fixed joining of the sup-
porting layers to one another at preferably regular intervals
in accoxdance with the invention additiona,lly improves the over-
all cha~a~cte~istics of the mat. This brings about a reciprocal
limita,tion of the ftbXous la,ye~ a~e,a,s, which can only be in-
te,rnal~y di~s,pl~ced but ar,e xec~pxoc,a,lly ~xed on a laxger ~ea
3Q ~as~s. Th~s o~yiates the ~sk o~ l~rge~ areas displacemen~s
of the ,f~,bxou~ mats duri;ng the mould~n~ process~ so that during
the de~ormation of the mat a more uniform material distribution
-- 7 --
X
1 ~6~779
is a~chieyed~ This'ef~ect is ~oughly cqm~axable ~ith the be-
hqv~oux of mode~ punct~oxm o~ l~near quilted eiderdown$ whexe
a uniform distribution o~ t~e fllling is still ensured if
the eidexdow~ ~s shook ox rolled up.
~ ccording to an ad~anta~geous further development of
the invention, the supporting la~er creping is a cross-creping.
This leads to an improved deformability of these layers.
It may also be advantageous if the supporting layers
are perforated (e.g. by needling~. The perforation makes the
supporting layers gas-permeable,,so that the mats according to
the invention can easily be thermally treated, e.g. with steam.
The gas permeability resulting from the perforation also aids
the extraction of moisture from the mat during moulding.
As the deformation characteristics of the supporting
layers need no longer be provided by the actual material and
instead result from the creping, all crepable materials can
be used for the supporting ~ayers for the mats according to
the invention.
Crepéd fabrics made from natural or synthetic fibres
can be used in the same way as creped plastic foils. Supporting
layers of creped metal foils are also possible, particularly
if the finished article must have a maximum resistance to mois-
ture action. Supporting layers made from creped paper can be
used with particular advantage, because this material can be
inexpensively obtained and is easily processed. Fibre mats
a,ccoxding ta the invention can also have creped Supporting
la~ers made from~'different matexiql,s on the top and bott~m of
the mat. Th~s makes it possible, e,g~ to provide the visible
~de a,f, t~e ~n~s,hed axt~cl,e ~th a, s~U~porting layer selected
,, 3Q on thq ~7als,i~s: o,~ decorative ~s~t~ndpo~ntsl ~hilst the su~poXting
l~ex used on t~e s,~de which ~s not v~$ible ~$ selected onl~ on
the ba~s~s of cost standpoints.
- 8 _
.
7 7 9
~ f ,im~xe~n~ta~ble suppo,rting l~ers are used it can
be pa~ticul,a~ly ad~antageous ~ox them to contain a thermosettin~,
duroplast~c ,r:es~n. ~lso the~ ca,n, for example, be preimpre~
nated ~ith ~henolic or melamine ~esins. Thus, during hot
mould~ng, A hi~H-finish, high-~tren~th surface layer is
obtained giving the flnished article sandwich chaxacteristics.
This is parLicularly advantageous when moulding thin-walled
articles.
Unlike in the prior art used as a basis for the inven-
tion and where the supporting layers used firmly adhere bytheir entire surface area to the fi~rous layer, it is not always
necessary with the ~ats according to the invention for there to
be a whole-area, firm adherence with the supporting layers.
As a result of the punctiform or linear interconnec-
tion of the supporting layers, areas are formed in which the
fibrous layer is adequately fixed between the supporting layers.
For special shaping problems, such a mat construction can be
advantageous. However, it is generally preferable to fix the
entire surface area of the supporting layers to the fibrous
layers by means of an adhesive. This improves the force
initiation conditions for the necessary re-shaping forces.
The adhesive used for this purpose can be adhesives
acting in a thermoplastic manner. However, it is also possible
to use contact or solvent adhesives. It is particularly economic
and advantageous from the manufacturing standpoint if the sup-
porting layers are precoated with the adhesive used.
The joining together of, the supporting layers in
punctifo~m or linear manner a,ccord~ng to the inVention can
take pla,ce by known textile aids~ e,g. by sewing or stitching.
It is,more a,dv,a,ntageous from the production standpoint if the
puncti~o~m or linear ~nterconnection of the supporting layers
is brought about by adhesion. In this case, the corresponding
_ g _
7 ~
adhesive joints o~ the suppa~ting l~exs ~e produced b~ the
adhesive used ~or br;nging about the whole~area adhesion o~ the
supporting l~er to the fibrous layer. This is the best solu~
ti~n from the production and cost standpoints.
Like the fibre m~ts according to the prior art, the
fibre mats accordin~ to the invention are preferably provided
with thexmosetting ~lnders and are mainly hot~moulded to moulded
articles. In this case, it is particularly advantageous if the
punctiform ox linear connections between the individual sup-
porting layers are made in such a way that the connection pointsor lines are dissolved in the mould heat.
During the closing of the compression mould the con-
necting points still exercise the hitherto described functions.
However, after intense contact with the mould surfaces during
the building up of the moulding pressure, the connecting points
dissolve and permit a material exchange in these local areas, I
so that the connection points or lines can no longer be seen
on the finished article. If the supporting layers are
joined together by textile processes, the solubility in heat
- 20 can be brou~ht about through using thermoplastic stitching
threads. In the case of adhesive joints, the joining strength
can be eliminated in the heat by using adhesives whose binding
force decreases in the presence of heat.
~ n important advantage of mats according to the inven-
tion is that their deformation characteristics is no longer
preponderantly determined by the qualit~ of the fibrous materials
used. Thus, e.~. in the p~ioX axt mats it is not possible or
is only possible to a limited extent to concomitantly use
p~oduçtion ~,a~Ste, because during the preparation of the latter
the fib~e ~eng~ is ~educed and qn add~tion of t~eated production
~aste con~sidexabl~ ~mpa,ixs the deform~tion char~cteristics of
the mat. In the case of the mats according to the invention,
- lQ -
;1,,
7 7 9
the de~o~mation ~roperties o.the $u~portin~ la~ers pxedo~inate.
Thus, lt ~s poss.~ble to u~e producti~n waste, including pro-
cessed sup~o~txng laye~s in the production of mats, thexeby
ensur~ng an ~nexpensive ~aste-free production, which saves
raw materials.
The central layers of these mats are pre-strengthened,
but in the initial state have a much lower density than in the
moulded state. The deformabilit~ of the central layers is im-
proved by thermal action, e.g. steam treatment prior to mould-
ing. If they are to be adequately deformable, they must havea moisture content a~ove 10%. This is a disadvantage from the
moulding standpoint,. because moisture extraction during the
hot final moulding process requires additional moulding time.
During moulding, the moisture content can lead to
! steam bubble for~ation, particularly if steam-impermeable sup-
porting layers are used. The perforation of the supporting
layers proposed for the purpose of eliminating this disadvantage
also fail~ to completely eliminate the risk of steam bubble
. formation, because the perforated proportion of the overall
surface area of the supporting layers is naturally small. Steam
bubble formation either leads to an increased quantity of waste
material or requires a correspondingly complicated moulding
procedure serving for the elim~nation thereof (intermediate
relief of the press during the moulding o~ the final article~
if these factors reduce the economy of the overall process.
Thus, according to an advantageous further development
of the ~nVention, the densit~ of the pre-strengthened central
la~e~ pr~aX to moulding ap~roximatel~ corresponds to its density
in the ~ s.~h.ed axt~cle/ th.e mo~stu~e level thereof heing
below lQ~
Th.:e low moistuXe content ~nitially has the advantage
that the moulding ti.me can ~e further reduced and that steam
.
1 :~6~7 ~9
bubbles do not occur in the moulded ~article, As the densit~
of the p~eStrengthened central layer corresponds appxoximatel~
to that 4f the finished art~cle, said layer has only a limited
tendenc~ to uncontrolled moisture absorption during inter-
mediate storage, so that ~ts preconditioning can be maintained
over a relatively long period. Further advantages result from
the fact that mats w~th central layers compressed to this
extent axe less voluminous a,nd consequently required less
storage space. In addition, their handling and transportation
stability is considerably improved compared with known mats.
The central layers of mats according to the invention
must also have adequate deforma~ilit~ in correspondingly,
highly compressed state, which generally requires additional
measures. Thus, for example, according to an advantageous em-
bodiment the central layer of such mats comprises at least one
sheet of creped paper or cardboard impregnated with thermo-
; plastic or duroplastic binders., The entire surface area of
creped papers, cardboard, woven or non-woven fabrics is uniformly
finely folded. Such structures consequently have an overall
surface area which is a multiple of that corresponding to the
external dimensions of the corresponding webs. They are there-
fore able to co~er the increase in the surface area required
for producing the three-dimensional shape from the "stored
sur~ace area" qf the pleating (crepin~. In the case of a
suitable shape of the crepxng folds (cross-creping in which the
cox~esponding web is finel~ folded ~in two directions at right
angles to one another), the corresponding material has a high
defo~a,b~l~t~ ~n all the d~,~ect,ions in questian. The increase
in the s,u~ace ,a,rea 2S m,a,de po~ble b~ $m~othing the folds,
without the ~a~e~ e~ng suhject to higher ten~ile stresses
resultinq fxom the deformati~n. ThuS, the creping of the
centra,l la~e~ permitsthe necessar~ deformation thereof and
- 12 -
,
JI
7 7 g
creped pape~s which have alxeady xeached their ~in~l density
can be prefabxicated and ~mpregnated without di~ficulty. They
can contain pulverulant fillers ~n addition to cellulose fibres.
Textile central la~ers can also be used for producing
mats according to the invention. Thus, for example, it is
possible for the central layer to comprise at least one sheet
of creped fabric or non-woven fabric impregnated with duro-
plastic or thermoplastic binders. Here again, the necessary
deformaBtlity of,the central la~er is obtained by impregnating
the per se inadequately deforma~le woven or non-woven fabric. ~,
Particularly favourable conditions are provided if
adequate deformability is ensured on the basis of the material
used for'the central layer of the mats. This is for example the
case if the central layer is a thermoplastic material filled
and/or reinforced preferably with cellulose or lignocellulose
materials. Such a mat can be hot-moulded without taking special
precautions. Particular advantages are obtained in connection
with moulded articles which are to be exposed to thermal stress-
ing in subsequent use if the creped supporting layers are made
from metal. This improves both the dimensional stability of
the articles in heat and also reduces the heat absorption due
to the favourable reflection conditions of the supporting layer. I
Creped papers, cardboards, fabrics, woven or non-
woven fabrics impregnated with binders, as proposed for the
centxal layer m~terial of the mats according to the inVention
can onl~ be creped in a limited thickness. According to a
further development ~f the inventiVe principle, it is therefore
advant~geous ~ use cent~al laxe~s~ compxising ,an intexla~inar
bond ~ ~ne X more mater~a,ls o~ t~e descxibed type, The in-
3Q diy~du~ e~t~ o~ the centx~l la~e~ c~n then be joined bysewing, $t~tch~ng or needling~
This can in particular be advantageous if the indi-
- 13 -
Xl
7 7 9
vidual sheets aXe ~or~ed fro~ p~pex, c~xdboard, ~oyen or non-
wo~en fabrics~ If textile ~oininy processes are used, it is
advantageous ~or the joininy threads to be made from thermo-
plastic ~aterials, which are ~eadily deformable during hot-
moulding. A further advantageous possibility of constructing
the core layer as an interlaminar bond is brought about by
producing the latter by an adhesive which softens in the
presence of heat.
This procedure has the advantage that the central
layers can be bullt up in random thickness from individual
layers with good deformation c~aracteristics, whose recipro-
cal joint becomes flexible during hot moulding, so that the de-
formation characteristics of the individual layers can be fully
utilized.
Due to the fact that in the interlaminar bond, the
materials can be combined virtually at random, further adap-
tation scope is obtai~ned for the chaxacteristics of the moulded
article.
Central layers according to the invention can be
wholly or partly produced from recycled materials. The creped
papers or cardboards of the central layers can for example be
recycled papers or cardboards, whose qualities are inadequate -
for other uses. This also applied to non-woven fabr~cs or
woven fabxlcs made from synthet~c an~or natuxal fibres. In
both casesl the primary products for producing the mats accord-
in~ to the invention can be obtained fxom the appropriate in-
dustxy.
~ t is also possible to prQduce the central layers
fxom fil~ed ~d~ox xe~nf~rced t~exmoplastic ~aterials using
low-~x~d~ thermQplastic mate~ial ~a,~t~, such as is e.g. obtained
in the foxm of coated papex w~ste ~nd cable industry waste and
which cannot be used for other purposes. Colour differences
- 14 -
1 1~4'~79
and impuritXes do not pla~ an ~mpo~tant part in connect,i,on
with the use ,a,ccording to the invention. Inadequate mechanical
stxength ch~racteristics, such as can occur when using mixed
waste, can be compensated by a suitable selection of the
$upporting layers.
The mats according to the invention are produced on
the basis of the prior art. The central layer is applied to
the lower supporting layer which serves as the conveyor belt.
The upper supporting layer is then supplied from a reel and
the assembly formed by the supp~rting layers and the central
layer is passed between the pairS of rollers used for prestreng-
thening and said layers are joined together. The perforations
can be obtained by pairs of rollers provided with corresponding
needles, wh~ch in each case pass through a supporting layer and
partly penetrate the central layer.
- 15 -
X!
