Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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A foam composite material impregnated with resin
The present invention concerns a foam composite material
which is impregnated with resin, a laminate containing that mat-
erial and a method for manufacture of such a laminate. Specifi-
cally, the invention concerns a foam composite material comprising
a web, which is impregnated with a thermosetting resin and which
contains expanded thermoplastic particles. The foam composite
material according to the invention is preferably used for modi-
fying surfaces.
Thus in a first aspect this invention provides a
laminate which comprises:
(i) at least one foam composite material including a
material in the form of a web, a cured resin and expanded thermo-
plastic particles essentially uniformly distributed in the resin
and in the web material, and
(ii) at least one further such a material of another mater-
ial, wherein the materials are bonded by the resin in the foam
composite material, whereby the expanded thermoplastic particles
constitute between 70 and 95 percent by volume of the foam compo-
site material parts of the laminate.
In a second aspect this invention provides a method forthe manufacture of a laminate, which method comprises:
(a) preparing a foam composite material containing a mat-
erial in the form of a web, a curable resin in -the B-stage and
expanded thermoplastic particles essentially uniformly distributed
in the resin and in the material,
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(b) assembling the foam composite material with at least
one further such material or another material and,
(c) bonding the materials to each other by finally curing
the resin.
The foam composite material may for instance be prepared
in the following way. A pre-condensate of a water based thermo-
setting resin is prepared conventionally and the amount of water
is adjusted in order to obtain 30 to 75 percent by weight dry
substance. I'o the solution obtained is added non-expanded thermo-
plastic particles, known as microspheres, in an amount such thatthe weight ratio microspheres:resin varies between 4:1 and 1:50
in the finished foam composite material. In the expanded condi-
tion, the microspheres preferably constitute 70-95, specifically
85-95, percent by volume of the foam composite material. A
material in the form of a web is impregnated with the mixture of
resin and microspheres in a conventional way, e.g. by immersing
the web in a bath of the mixture, by spraying the mixture on the
web or by adding the mixture in connection with the formation of
the web. The impregnated web, the degree of impregnation of which
can be adjusted e.g by rolls, is then treated thermally, suitably
with circulating hot air having a temperature of 80-150C so that
the resin sets to the B-stage and the microspheres expand. It
should he noted in this context that a thermosetting resin in the
A-stage is meltable, poorly cross-linked and soluble in acetone
and other solvents. A C-stage resin is not meltable, completely
cross-linked and insoluble. The B-stage is a stage between the
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A-stage and the C~stage.
Thermosetting resins that may be used according to the
present invention are resins based on formaldehyde with urea,
phenol, resorcinol or melamine.
The web material may consist of woven or non-woven
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organic or inorganic material and specifically glass fib- I
re, mineral fibre, cellulose fibre and polyester may be f
mentioned. It is also important that the web material has
sufficien~porosity so that it can be impregnated with the
5. mixture ~ resin and microspheres in a satisfying manner.
Further, the web material must not be taken too thick and
suitably the thickness may vary between 0.1 and 5 mm. The
reason why the web material must be thin is that otherwise
there may be a non-uniform expansion of microspheres owing
10. to the fact that, at the thermal treatment, superficially
situated microspheres expand first and these expanded mic-
rospheres form a thermally, insulating layer preventing
those microspheres which are situated more deeply or more
central from expanding and if this happens a product of
15. inferior quality, which is not homogenous, will be obtain-
ed.
It is also possible to add the resin and/or the mic-
rospheres in connection with the formation of the web, e.g. f
by the direct manufacture of the web by depositing a fibre
20. suspension also containing resin and/or microspheres. Al-
ternatively the resin and/or microspheres can be added in
connection with deposition of fibres from air into a web.
A so prepared web can be treated in the same way as an im-
pregnated ready web, i.e. being heated afterwards to ex-
25. pand the microspheres and to transform the resin into the
B stage. It is, however, also possible in these cases to
add already expanded particles to the web at deposition of
this since no impregnation step is required. This can be
done with special simplicity at deposition of the web from
30. air since then the buoyancy of the expanded particles cau-
ses no problems. When the microspheres are expanded before
or during the deposition of the web it is possible to make
the web thicker than when the expansion is made by heating
the impregnated web since no heat transfer problems will
35. arise in this connection. The manufacture of a thicker
layer without the need for laminating together several thin
sheets is of value in certain connections, especially when
the strength demands are lower. It is also possible to pro-
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duce in this way first a very porous web, which by pressing
can be given a variable density or a more complicated final
shape. The product can otherwise be used in the same way as
a foam composite material prepared by impregnation of a rea-
5. dy web.
The microspheres which are used when preparing thefoam composite material according to the present invention
have shells which may be made up of copolymers of vinyl
chloride and vinylidene chloride, copolymers of vinylidene
10. chloride and acrylonitrile, copolymers of vinyl chloride and
acrylonitrile and copolymers of styrene and acrylonitrile.
Further, copolymers of methyl metacrylate containing up to
20 percent by weight styrene, copolymers of methyl metacry-
late and up to 50 percent by weight of combined monomers of
15. ethyl metacrylate, copolymers of meth~l m~acryl~te and up
to about 70 percent by weight of ort~o~b~Co~r/ost Sro~c~m~aey be
mentioned. The particle size of the non-expanded particles
and, accordingly, the expanded particles may vary within
broad limits and is selected with respect to the properties
20. desired for the finished product. Examples of particle si-
zes for the non-expanded spheres are l)um to 1 mm, prefer-
ably 2 ~m to 0.5 mm and specifically 5)um to 50 ~m. At the
expansion the diameter of the microspheres increases by a
factor 2-5. The non-expanded microspheres contain volatile,
25. liquid blowing agents which are vaporized at the applica-
tion of heat. The blowing agents may consist of freones,
hydrocarbons, such as n-pentane, isopentane, neopentane,
butane, isobutane or other blowing agents, that are used
conventionally in microspheres of the type specified above.
30. Suitably 5-30 percent by weight of the microspheres may
consist of blowing agent. The microspheres may be added to
the resin solution in the form of dried particles or in the
form of a suspension, for instance in an alcohol such as
methanol.
35. As mentioned previously, the ratio resin to micro-
spheres in the impregnating solution may vary within broad
limits and this ratio affects the properties of the final
product. Correspondingly, starting from certain fields of
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employment and certain desired properties of the final pro-
duct it is also possible to select a suitable ratio resin
to microspheres in the mixture. This ratio can easily be
determined by preparatory experiments in the laboratory.
5. Different additives such as stabilizers, coupling
agents, fillers, flame retarding agents and/or pigments
may be added to the mixture of resin and the microspheres
if desired or required.
The foam composite materials according to the inven-
10. tion may be used in combination with substrates or support-
ing layers, preferably wood bades supporting layers, for
preparing laminates and these laminates are called hetero- I
genous laminates in the following text. It is also possib- !
le to laminate several layers of the foam composite mate-
15. rial according to the invention for the preparation of
multilaminates and these laminates will be called homogen-
ous laminates in the following text. It is certainly also
possible to produce mixed laminates containing at least
one homogenous laminate together with at least one other
20. material.
In the preparation of the heterogenous laminates the
foam composite material according to the invention is com-
bined with an optional supporting layer and the combina-
tion of the foam composite material and the supporting
25. layer is compressed at an elevated temperature. In this
process time, temperature and pressure are chosen mainly
with consideration taken to the type of resin used. Often
the time for the pressing may vary between 20 seconds and
20 minutes. The temperature may vary between 100 and 180C
30. and the pressure between 0.1 and 3 MPa. If the supporting
layer has a rough and uneven surface especially attractive
effects may be attained by the foam composite material
penetrating the cavities and filling these up, while the
"free" surface of the foam composite material, i.e. the
35. surface that is facing the press plate, becomes complete-
ly smooth, as the microspheres adjacent to the press pla-
te collapses by the pressure while expanded microspheres
adjacent the rough surface of the supporting layer penet-
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rates into the cavities filling these up. Accordingly~ alevelling out of the surface is effected. In practice this
effect of levelling out can be achieved for example in con-
nection with the peparation of plywood. In conventional ply-
5. wood preparation si~ed veeners are prepared first and theveneers are compacted to plywood. In order to get a satis-
fying surface the rough surface is then ground and a sur-
face coating is then pressed onto the plywood surface. Us-
ing the foam composite material according to the present
~0. invention it is possible to press together several veneer
sheets and a thin sheet of a foam composite material in
one single step and, after pressing, there is obtained a
hard completely smooth surface layer consisting of a foam
composite material according to the invention, in which ma-
15. terial the resin is completely cured and the microsphereshave col]apsed partly. Other properties which can be obtain-
ed in heterogenous laminates containing a foam composite ma~
terial according to the invention are improved flame retard-
ing properties. It is possible to get a laminate surface
20. suitable for painting and (wall) paper covering, to get a
higher flexural modulus and a surface that is water repell-
ant and thermal insulating. In sheet material a decrease of
the skew of the plate, may be achieved.
Lamination with wood gives a material with the sur-
25. face properties of wood but with a reduced density, which
is usable for example in packings, coachworks or interior
fittings. Lamination with metals, especially aluminium
sheets or aluminium foils, gives a material with good and
lasting surface properties and high stiffness but with re-
30. duced density, which can be used for example in packings,coachworks, building frontages, signboards or travel requi-
sites. Lamination with papers, impregnated with formalde-
hyde-based resins, gives materials with resistant and/or
decorative surfaces, high stiffness and low density suited
35. for example in interior fittings, panels and signboards.
In order to improve the adhesion between the impregnated
paper and the foam composite material and to reduce the
effects of the brittleness of the material it is in these
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cases advantageous to arrange a middle sheet of for examp-
le cardboard. Lam;nation of materials with thermoplastic
surfaces can give light decorative products suitable in
interior fittings and for panels. A coating of nylon
5. flocks on the foam composite material gives a decorative
and durable surface allowing pin attachments, which pro-
duct is usable for example in notice-boards, interior
fittings and signboards. Similar properties and uses
flows from laminates with textiles. Numerous other hetero-
10. genous laminates are of course possible. It is also possib-
le to adhere the foam composite material of the invention
against non-solid materials at the formation of these, for
example to foam polyuretane against the foam composite ma-
terial, preferably between two sheets of these, whereby not
15. only a light and in relation to the weight stiff product is
obtained but also is achieved a more uniform foaming of the
polyuretane material due to the low heat conduction and heat
capacity of the foam composite material. The covering sheets
also gives a fire resistant effect reactive to the polyure-
20. tane foam. The mentioned properties are of special valuewhen using the product as building elements. It is general-
ly possible in heterogenous laminates to introduce a middle
sheet between the different materials in order to improve
stiffness, adhesion and dent resistance. A suitably select-
25. ed middle layer can be bonded against the foam compositematerial by use of the remaining bonding capacity of the
resin in the material in accordance with a general purpose
of the invention and at the same time, on its other side,
allow glueing to materials normally not bondable by the re-
30. sin of the foam composite material. For example paper or a
fiber web can be used for this purpose and it is especial-
ly advantageous that t~le sheet is impregnated with a cur-
able resin, preferably the same as in the foam composite
material or a resin compatible with this.
35. The homogenous laminates are prepared with pressure
times varying between 1 minute and 30 minutes. The pressu-
re may suitably vary between 0.01 and 0.5 MPa and the tem-
peratures between 100 and 150C. Preferably such conditions
are chosen that the expanded microspheres do not collapse.
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A lig~t weigilt and strong material which for example may
be used in the building trade is obtained if the micro-
spheres do not collapse. Furthermore, it should be noted
that the ~ly4~ can be laminated by g]ueing without the
5. application of heat.
The foam composite material is heat mouldable in
non-cured condition, which for example allows formation
of double-bent surfaces in connection with lamination.
Such a moulding can take place both at manufacture of
10. homogenous laminates and at manufacture of heterogenous
laminates wherein the other materials are preformed or
allows deformation under the lamination procedure.
The invention will be illustrated more in detail
in the following non limiting examples.
15. Example 1
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A 50 g/m~ felt of glass fibre was impregnated with
a dispersion of VDC/ACN microspheres from KemaNord AB and
a phenol resin solution 9916 from AB Casco having dry sub-
stances of 60 %,wherein the ratio of the dry substances
20. MS:PF is 2:1 (VDC = vinylidene chloride, ACN = acrylonitri-
le, MS = microspheres, PF = phenol formadelhyde resin).
When the felt has been immersed in the impregnating
bath excessive dispersion is pressed away by rolls. Then
the felt is treated with air (120C) causing the water to
25. leave until 7 percent by weight remain and simultaneously
the microspheres expand. A homogenous larninate was prepar-
ed by superimposing four layers and pressing at 0.25 MPa,
125C for 10 minutes.
The following product was obtained:
Thickness 7.10 mm
Density 162 kg m 3
Flexural modulus248 N/mm2
Flexural strength4.68 N/mm2
E modulus pressure15.66 N/mm2
Compression strength, 10 % 2
deformation 0.78 N/mm
Smoke 2.8 % KemaNord PM 227
Smoke develop- ¦
ment according
to Arapahoe
Oxygen index 45 ASTM 2863
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T~lis product can preferably be used as a core or
surface material in sandwich structures. The homogenous
laminate can be moulded at a temperature of about 120C.
Example 2
5. The process according to example 1 was repeated but
the ratio MS:PF was 1:1 (calculated on the dry substances).
The following product was obtained:
Thickness 4.09 mm
Density 264 kg m 3
Flexural modulus 574 N/mm2
Flexural strength 12.22 N/mm2
E modulus pressure 31.11 N/mm2
Compression strength, 10 %
deformation 1.89 N/mm2
Smoke 2.4 % KemaNord PM 227
Smoke develop-
ment according
to Arapahoe
Oxygen index 45 ASTM 2863
This product can be used in sandwich struc~ures.
Example 3
10. The process according to example 1 was repeated
but the ratio MS:PF was 1:2 (calculated on the dry
substances).
The following product was obtained:
Thickness 3.1 mm
Density 306 kg/m 3
Flexural modulus 799 N/mm2
Flexural strength 20.16 N/mm2
! E modulus pressure 40.19 N/mm2
Compression strength, 10 %
deformation 3.85 N/mm2
Smoke 1.8 % KemaNord PM 227
Smoke develop-
ment according
to Arapahoe
Oxygen index 42 ASTM 2863
Flame-proof surface layer class 3 NT 004
Average smoke density 9 %
, The product can be used in sandwich structures.
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Example 4
A foam fibre layer was prepared according to examp-
le 1 but the ratio MS:PF was 1:2, calculated on the dry
substance. This sheet was pressed onto a plasterboard at
5. a pressure of 0.4 MPa and a temperature of 120C for 10
minutes, and a decorative surface suitable for embossing
was obtained. At fire testing NT 004 class 1 is obtained
on the surface and no smoke is developed.
Example 5
10. Example 4 was repeated but a 10 mm unground spruce
plywood was used as a supporting layer.
A levelling out of the surface was obtained and
the surface was waterproof and suitable for painting
and covering with wall paper.
15. The surface can further be decorative and suitable
for embossing. The products have improved stiffness and
are as far as fire is concerned classified as flame-proof
surface layer class 3, average smoke density 13 %.
