PROCEDE DE FABRICATION D'UN PRODUIT FAIT D'UN MATERIAU RECYCLABLE

METHOD AT THE MANUFACTURING OF A RECYCLABLE PRODUCT MATERIAL

Abrégé français

Cette invention concerne un procédé de fabrication d'un produit fait d'un matériau recyclable et possédant une résistance prédéterminée dans un intervalle de taux de déformation prédéterminé. Ce produit se compose d'au moins un matériau matriciel et d'au moins un matériau fibreux. Les matériaux matriciel et fibreux sont choisis de manière à ce que les valeurs de leurs modules d'élasticité (E¿ij?), de cisaillement (G¿ij?) et de leurs coefficients de Poisson (?¿ij?) permettent d'obtenir une répartition discontinue des quantités desdits matériaux matriciel et fibreux pour des éléments de volumes différents faits dudit matériau. D'après cette invention, il est également souhaitable qu'une courbe graphique représentant une répartition continue de la taille des fibres du matériau composant le produit, présente une symétrie pour des éléments de volumes différents faits dudit matériau.

Abrégé anglais

The invention relates to a method for the manufacture of a recyclable product
material in order to achieve a predetermined strength within a predetermined
strain rate interval. The product material comprises at least one matrix
material and at least one fibre material. The matrix and fibre materials are
chosen so that the values of their moduli of elasticity (Eij), moduli in shear
(Gij) and the Poisson's ratios (ij) assume a discontinuous distribution of the
said matrix and fibre material quantities within different volume elements of
the product material. It is further intended that a display curve defining a
continuous distribution of a fibre size of the product material should exhibit
symmetry in different volume elements of the product material.

Revendications

4
Claims
1. Method for the manufacture of a recyclable product material, comprising at least
one matrix material and at least one fibre material in order to achieve a
predetermined strength within a predetermined strain rate interval in the product
material, characterised in that in different volume elements of the product material
the matrix and fibre materials are selected in such a way that the values of their
moduli of elasticity (Eij), the moduli in shear (Gij) and the Poisson's ratios (Oij)
assume a discontinuous distribution and that a display curve defining a continuous
distribution of fibre size of the product material exhibits symmetry.
2. Method according to claim 1, characterised in that through the choice of a fibre
material or mixture of at least two fibre materials it is ensured that the display
curve of the fibre material/the mixed fibre materials is approximately symmetrical
about a predetermined mean value.
3. Method according to claim 1, characterised in that the form factor of the fibre
material/the mixed fibre materials, that is the ratio of fibre length to fibre
diameter, exhibits dispersion.
4. Method according to claim 3, characterised in that the respective form factors of
the said fibre materials are such that the particle size of the contaminations is
exceeded, that is to say that the fact that one or more of the matrix/fibre materials
is contaminated does not have a detrimental effect on the strength of the product
material.

Description

CA 02231811 1998-03-11
W O 97/10935 PCT/SE96/01124
Method at the manufacturing of a recyclable product materia
The present invention relates to a method for the manufacture of a recyclable product
material, comprising at least one matrix material and at least one fibre material in
order to achieve a predetermined strength within a predetermined strain rate interval
5 in the product material.
Only recently has the handling of retumable plastic for recycling the latter assumed
the priority which is desirable with regard, among other things, to environmental
aspects, economic use of energy etc. People have begun, with some success, for
10 example~ to collect packaging film from agriculture and industry in order to
manufacture granulate from the re~umed film
WO 93/25609 and WO 94/09959. for example, are already known in this field.
These publications describe methods and appliances for recycling retumable plastic
1 ~ and fibres.
One problem with this is the degree of contamination and the large number of
different types of plastic with different melt indices exhibited by the retumable
plastic. as a result of which the manufactured product material does not achieve the
20 predeterrnined strength. The problem is related to the fact that the granulate nozzle
and filtering equipment become clogged, which gives a very inhomogeneous final
product.
In the above-mentioned publications there was no indication of any solution to this
2 5 strength problem.
The object of the present invention is to achieve a predetermined strength for apredetermined strain rate interval in a recyclable product material of the said type, in
order to thereby eliminate or a~ least reduce the effect of the said disadvantages
30 associated with earlier manufaclure of recyclable produc( material. To do this it is
necessary to produce the ~reatest internal microstresses possible in the product

CA 02231811 1998-03-11
WO 97/1093~ PCT/SE96/01124
material. This is achieved according to the invention in that in different volume
elements of the product material the matrix and flbre materials are selected so thal
the values for their moduli of elas~icity, shear moduli and Poisson's ratios assurne a
discontim~ous distribution, and that a continuous distribution of a display curve
5 defining the fibre size of the product material exhibits syrnmetry.
According to another special characteristic of the invention the form factor of the
fibre material/the mixed fibre materials, that is the ratio of fibre length to fibre
diameter, exhibits a dispersion by means of which a majority of fibres can be made to
10 bridge islands of inhomogeneities which would otherwise give rise to defective
adhesion bet~veen the fibres.
As will be appreciated from a further special characteristic of the invention, the said
distributions are preferably so great that the fact that one or more of the matrixlfibre
15 materials is contaminated does not have a detrimental effect on the strength of the
product material.
According to further characteristics of the invention the respective forrn factors of the
said fibre material are such that the particle size of the contaminations is exceeded,
20 that is to say the fact one or more of the matrix/fibre materials is contaminated does
not have a detrimental effect on the strength of the product material.
Further advantages of the invention will be evident from the following description of
this, referring to the drawing in which fig. I is an example of a display curve in the
25 method accordinP to the invention. Fig.2 shows various volume elements in a
product material.
The manufacture of a recyclable product material by the method according to the
invention is done using equipment of conventional type familiar to the person skilled
30 in the art supplemented by measuring devices for checking the moduli of elasticity
and moduli in shear of the matrix and flbre materials, together with the Poisson's
ratios calculated from these values. Should the discontinuous distribution of the

CA 02231811 1998-03-11
W O 97110935 PCT/SE96101124
above-mentioned quantitles characteristic of the invention not be obtained, a manual
or automatic correction is pertorrned, whereupon that material in which the quantities
did not attain the discontinuous distribution is fed back into the process, that is to say
the material passes through the process one more time.
With regard to the display curve defining the fibre size of the product material,
reference is made to the example in fig. l . In this display curve it is assumed that the
agglomeratelgranulate has a maximum diarneter of 4mm. The majority of the fibreshave here been chosen with lengths of about 2mm with a dispersion according to the
1 0 curve.
Fig.2 is intended to show a specimen l of a recyclable product material manufactured
by the method according to the invention. Agglomerate/granulate have been
combined as N volume elements lal, la2 ... with different preferred alignments of
15 the fibres, which are included in the various volurne elements. This consequently
means, according to the invention, that for each such volume element the values of
the modulus of elasticity (Ejj), the modulus in shear (Gjj) and the Poisson's ratio (o jj)
will differ from the values of similar quantities for adjacent volume elements. This
confers great intemal couple stresses.

Dessin représentatif