Note: Descriptions are shown in the official language in which they were submitted.
CA 02391726 2002-O1-30
WO 01/10637 _ 1 _ PCT/EP00/07065
METHOD OF PRODUCING VEHICLE INTERIOR MATERIAL HAVING SANDWICH
STRUCTURE
The present invention relates to a method of producing a vehicle interior base
material being light and
excellent in dimensional stability, such as a ceiling material or a door trim
material for a vehicle, and
to a laminate having a sandwich structure that can be used as an interior base
material for a vehicle.
As a technique for producing a vehicle interior base material having a
sandwich structure, there is
proposed a method of producing a molded product in which isocyanate is
immersed in a flexible
polyurethane foam or a rigid polyurethane foam; water and a urethanization
catalyst are added
thereto; and both surfaces are reinforced with glass mats (Japanese Patent
Kokoku Publication No.
63-7577 (7577/1988) titled "Method of producing a light and rigid or semi-
rigid composite panel").
Further, there is also proposed a method of sandwiching a polyurethane foam,
which has open cells
and is moldable at an ordinary temperature, between two glass mats provided
with an adhesive and
thermoforming it (Japanese Patent Kokai Publication No. 04-211416
(211416/1992) titled "Method
of producing a rigid polyurethane foam having open cells and being moldable at
an ordinary
temperature, and use of the same for producing a molded article"). In all of
these methods, glass
fibers are used as a reinforcing material. These glass fibers, though being
extremely excellent in
reinforcing effects, are considerably expensive and irritant to operator's
skin, and are non-flammable
when discarded, so that the disposal thereof is a great problem.
There is already an example in which a woven fabric made by weaving fibers
made of intertwined
hemp with a considerably rough mesh of 2 to 3 mm is used as a reinforcing
material (Opel: Vectra
etc.). However, if a woven fabric is used as a reinforcing material, wrinkles
are generated at a draw-
formed portion because it is not fi~eely expandable or contractible. Further,
since an adhesive is not
easily immersed into the inside of intertwined fibers, the curing is
insufficient and the surface is likely
to have unevenness.
CA 02391726 2002-O1-30
WO 01/10637 PCT/EP00/07065
-2-
As a result of intensive studies made to obtain a molded product that can be
recycled easily and are
light and inexpensive without using glass fibers as a reinforcing material, we
have discovered that
vegetable fibers such as wood fibers, bamboo fibers, cut hemp, and cut kenaf
can be fizlly used in
place of glass fibers.
In addition, we have discovered that it is advantageous in ternis of costs and
effects if vegetable fibers
cut to a suitable length and an adhesive are mixed and spread uniformly on a
polyurethane foam.
The present invention provides a method of producing a vehicle interior
material having a sandwich
structure, comprising the steps of
(I) stacking
(a) a thermoformable polyurethane foam having open cells and a density of 20
to 100
kg/m3,
(b) vegetable fibers of 100 g/m2 to 300 gJmz positioned on both main surfaces
of the
polyurethane foam (a),
(c) a thermosetting adhesive foaming bonds between the polyurethane foam (a)
and
the vegetable fibers (b) and bonds between the vegetable fibers (b) each
other, and
optionally
(d) a skin for surface decoration and/or a filin preventing the exudation of
the
adhesive,
(II) charging the laminate into a mold having a temperature of 80 to 150
°C, and closing the
mold to cure the adhesive, and
(III) demoldulg a molded product after the curing of the adhesive,
CA 02391726 2002-O1-30
WO 01/10637 PCT/EP00/07065
-3-
characterized in that the size of the vegetable fibers is adjusted to be a
diameter of at most 1.0 mm
and a length of 10 mm to 100 mm.
The present invention also provides a laminate comprising:
(A) a layer composed of a thermofomlable polyurethane foam having open cells
and a density of 20
to 100 kg/m3; and
(B) layers composed of vegetable fibers of 100 g/m2 to 300 g/m3 and a
thermosetting adhesive,
the (A) layer being sandwiched between the two (B) layers,
wherein the vegetable fibers have a diameter of at most 1.0 mm and a length of
10 mm to 100 mm.
The laminate is preferably such that the polyurethane foam is a rigid
polyurethane foam; the
thermosetting adhesive is an adhesive comprising an aromatic polyisocyanate,
water, a catalyst, and
optionally a polyol; and the vegetable fibers are those obtained by cutting or
grinding of hemp, kenaf,
sisal fibers, bamboo fibers, wood fibers.
The thermoformable polyurethane foam having open cells may have a density of
20 to 100 kglm3,
for example, 25 to 40 kg/m3, particularly 25 to 35 kg/m3.
The polyurethane form is preferably a rigid polyurethane foam.
The rigid polyurethane foam is one obtained by reacting a polyisocyanate
component and a polyol
2 5 component.
The polyol component may comprise a polyol, a catalyst, a foaming agent, and
optionally a flame-
retarder, a viscosity reducer, and a surfactant.
The polyurethane foam may be sheet-like, and may have a thickness of 3 to 8
mm.
CA 02391726 2002-O1-30
WO 01/10637 PCT/EP00/07065
-4-
The vegetable fibers are distributed uniformly on both sides of a polyurethane
foam layer at 100 to
300 g/m2, for example, at 100 to 200 g/m2 as a reinforcing material.
It is necessary that the size of the vegetable fibers is adjusted to a
diameter of at most 1.0 mm (for
example, 0.2 to 0.8 mm) and a length of 10 to 100 mm (for example, 15 to 50
mm). If fibers having
a diameter exceeding 1.0 mm are used as a reinforcing material, unevenness
will appear on the
surface of the molded product, thereby considerably deteriorating the
appearance. The diameter as
used herein refers to the smaller of the longitudinal and lateral dimensions
of the fiber cross section.
These fibers can be cut to a length of 10 to 100 mm by means of a simple
equipment. If the length is
smaller than 10 mm, the required reinforcing effects are not obtained, whereas
if the fibers are too
long, they will be entangled with each other, so that they cannot be dispersed
uniformly on the foam.
It is necessary that the size is adjusted to be between 10 and 100 mm in order
that the fibers can be
spread comparatively easily and uniformly on a molded product such as a
vehicle ceiling material
having a large area, and in order to obtain sufficient reinforcing effects.
The vegetable fibers may be those obtained by cutting or grinding of
vegetables mainly containing
cellulose. The vegetable fibers may be, for example, hemp, kenaf, sisal
fibers, bamboo fibers, wood
fibers. The wood fibers are obtained from wood. The wood may be, for example,
cedar, pine,
zelkova, sun tree, hiba arborvitae, cherry, poplar, or fir.
The thermosetting adhesive forms bonds between the polyurethane foam and the
vegetable fibers
and bonds between the vegetable fibers each other. In the case where the
vegetable fibers are bonded
to each other, the adhesive is immersed among the vegetable fibers to form a
layer made of the
vegetable fibers and the adhesive.
The thermosetting adhesive may be an adhesive comprising an aromatic
polyisocyanate, water, a
catalyst, and optionally a polyol.
The aromatic polyisocyanate may be, for example, tolylene diisocyanate,
diphenylmethane
diisocyanate, or polymethylene polyphenyl polyisocyanate (polymeric MDI), and
is preferably
polymeric MDI.
CA 02391726 2002-O1-30
WO 01/10637 PCT/EP00/07065
-5-
The water may be 10 to 50 parts by weight, for example,15 to 30 parts by
weight, based on 100 parts
by weight of the aromatic polyisocyanate.
The catalyst may be, for example, an amine such as monoamine, diamine, or
triamine (for example,
bis(dimethylaminoethyl) ether, N,NCI'~1'~T"-pentamethyldiethylenetriamine,
triethylenediamine, or
dimethylethanolamine).
The catalyst may be from 0.1 to 1.0 part by weight, for example, from 0.2 to
0.5 part by weight,
based on 100 parts by weight of the aromatic polyisocyanate.
The polyol to be used may be, for example, a polyhydric alcohol (for example,
ethylene glycol,
glycerin, trimethylolpropane, pentaerythritol, sorbitol, sugar), a polyether
polyol, or a polyester
polyol.
Examples of the polyether polyol include a polyether polyol obtained by adding
an alkylene oxide
(for example, propylene oxide or ethylene oxide) to a polyhydric alcohol, and
a polyether polyol
obtained by adding an alkylene oxide (for example, propylene oxide or ethylene
oxide) to an
aliphatic amine (for example, monoethylamine, ethylenediamine, N,N-
dimethylethylamine, or
diethylenetriamine).
The polyether polyol may have a hydroxyl value of 100 to 1000 mgKOH/g, for
example, 300 to 600
mgKOH/g.
The amount of polyol may be at most 10 parts by weight, for example, from 2 to
5 parts by weight,
based on 100 parts by weight of the polyisocyanate.
The amount of the thermosetting adhesive may be from 50 to 300 parts by
weight, for example, 70 to
150 parts by weight, based on 100 parts of the vegetable fibers.
CA 02391726 2002-O1-30
WO 01/10637 PCT/EP00/07065
-6-
Optionally, a skin for surface decoration and/or a filin preventing the
exudation of the adhesive may
be provided on the layer made of the vegetable fibers and the thermosetting
adhesive. The skin for
surface decoration may be woven or non-woven fabric of polyolefin, polyester
or polyamide, a vinyl
leather, or the like. The thickness of the skin for surface decoration may be,
for example, from 0.1 to
3 mm.
The film preventing the exudation of the adhesive may be an olefin film or a
polyamide film. The
thickness of the film preventing the exudation of the adhesive may be, for
example, finm 10 to 40 .m.
The laminate can be produced, for example, by applying (for example, applying
with a spray) a
thermosetting adhesive on both surfaces of a polyurethane foam, spreading
vegetable fibers on both
surfaces, optionally disposing a skin for surface decoration and/or a filin
preventing the exudation of
the adhesive to give a laminate, charging the laminate into a mold heated to a
temperature of 80 to
150 °C, for example,120 to 140 °C. for pressurizing, curing the
adhesive, and demolding the molded
product from the mold.
Alternatively, after the thermosetting adhesive or one component (for example,
aromatic
polyisocyanate) of the thermosetting adhesive is mixed with the vegetable
fibers in advance, the
mixtlue may be applied on both surface of the polyurethane foam.
In the laminate, the thickness of the layer made of the polyurethane foam may
be from 4 to 8 mm,
and the thickness of the layer made of the vegetable fibers and the
thermosetting adhesive may be
fi-om0.2to2mm.
The laminate of the present invention can be used as an interior base material
for an automobile, for
example, a ceiling material or a door trim material for an automobile.
Hereafter, Examples will be shown, and the present invention will be
specifically explained.
CA 02391726 2002-O1-30
WO 01/10637 PCT/EP00/07065
_7_
Examples
In the following examples, the evaluation of a molded product was performed as
follows.
(1) Flexural modulus
The flexural modulus was measured according to JIS K6301. A sample having a
length of
150 mm and a width of 50 mm was cut out from a molded product, and the
flexural
modulus was measured with an interfizlcrum distance of 100 mm and a test speed
of SO
mm/min.
(2) Moldability
The moldability was judged by the rigidity at the demolding, the damage degree
of the skin
for surface decoration, and the like.
Example 1
Polymeric MDI (SBU Isocyanate 0418, manufactured by Sumitomo Bayer Urethane
Co., Ltd.) was
applied in an amount of 70 g/m2 by a spray on both surfaces of a
thermoformable rigid polyurethane
foam sheet (size: 30 cm x 30 cm x 5.5 mm) having open cells and a weight per
unit area of 200 g~mz.
Neat, water containing 1 wt% of a urethanization catalyst (SBU Catalyst H544,
manufactured by
Sumitomo Bayer Urethane Co., Ltd.) was applied in an amount of 20 g/m2 by a
spray.
Then, wood fibers (type: groundwood pulp) having a diameter of 0.7 mm and a
length of 10 to 50
mm were spread at a basis weight of about 150 g/m2 on both surfaces, and a
nonwoven fabric
(polyester: thickness 0.1 mm) of about 40 glm'- was disposed on both surfaces
to give a laminate, and
the laminate was pressurized for 60 seconds in a mold at 130 °C. to
fabricate a molded product
having a thickness of 5 mm.
CA 02391726 2002-O1-30
WO 01/10637 PCT/EP00/07065
_g_
This molded product, though having a density (apparent density) of 0.15 g/cm3
and a weight per unit
area of 750 g/m2 to be extremely light, exhibited a flexural modulus of 3,000
kg/cm2 and had a full
capability as a ceiling material.
Example 2
Water containing 1 wt% of a urethanization catalyst (SBU Catalyst H544,
manufactured by
Sumitomo Bayer Urethane Co., Ltd.) was applied in an amount of 20 gJm2 by a
spray on both
surfaces of a thermoformable rigid polyurethane foam sheet (size: 30 cm x 30
cm x S.5 mm) having
open cells and a weight per unit area of 200 g/m2.
To 100 parts by weight of bamboo fibers having a diameter of 0.7 mm and a
length of 10 to 50 mm
were added 50 parts by weight of polymeric MDI (SBU Isocyanate 0418,
manufactured by
Sumitomo Bayer Urethane Co., Ltd.), and the mixture was well stirred.
The mixture of polymeric MDI and bamboo fibers was spread uniformly at a basis
weight of about
200 g/mz on both surfaces of the polyurethane foam sheet having the
urethanization catalyst-
containing water applied thereon.
Onto the outside thereof, about 200 g/m2 of a skin (polyester: thickness 1 mm)
for surface decoration
was disposed to give a laminate, and the laminate was pressurized for 60
seconds in a mold at
130 °C. to fabricate a molded product having a thickness of S mm.
This molded product, though having a base material density (apparent density)
of 0.14 g/cm3 and a
weight per unit base material area of 700 g/m2 to be extremely light,
exhibited a flexural modulus of
3,000 kg/cmZ, and the skin for surface decoration had not been damaged at all.
CA 02391726 2002-O1-30
WO 01/10637 PCT/EP00/07065
-9-
Comparative Example 1
Water containing 1 wt% of a urethanization catalyst (SBU Catalyst H544,
manufactured by
Sumitomo Bayer Urethane Co., Ltd.) was applied in an amount of 20 g/mz by a
spray on both
surfaces of a thermoformable rigid polyurethane foam sheet (size: 30 cm x 30
cm x 5.5 mm) having
open cells and a weight per unit area of 200 ~m2.
To 100 parts by weight of wood fibers (groundwood pulp) having a diameter of
about 2 mm and a
length of 2 to 15 mm were added 50 parts by weight of polymeric MDI (SBU
Isocyanate 0418,
manufactured by Sumitomo Bayer Urethane Co., Ltd.), and the mixture was well
stirred.
The mixhwe of polymeric MDI and wood fibers was spread uniformly at a basis
weight of about 200
g/m2 on both surfaces of the sheet having the urethanization catalyst-
containing water applied
thereon.
Onto the outside thereof, about 200 g/m2 of a skin (polyester: thickness 1 mm)
for surface decoration
was disposed to give a laminate, and the laminate was pressurized for 60
seconds in a mold at
130 °C. to fabricate a molded product having a thickness of 5 mm.
This molded product had a base material density (apparent density) of 0.14
g~cm3 and a weight per
unit base material area of 700 g/m2. The rigidity at the demolding time was
low, and it was di~cult
to demold the molded product Moreover, the flexural modules was only as much
as 1,000 kg/cmz,
so that a molded product usable as a ceiling material could not be obtained.
The molded product obtained according to the present invention, in spite of
being extremely light,
exhibits a high rigidity.
