Title of Invention

"A THERMOPLASTIC COMPOSITE SHEET COMPRISING FIBER IMPREGNATED PREPREG LAYER MANUFACTURING METHOD AND ARTICLE MANUFACTURED THEREOF"

Abstract A thermoplastic composite sheet (1) comprising: a center layer (10) made of a thermoplastic composite material containing thermoplastic resin; and a continuous reinforcing fiber-impregnated prepreg layer (20) laminated on at least one surface of the upper surface and lower surface of the center layer (10), the prepreg layer (20) comprising 5-65% by weight of reinforcing fibers and 35-95% by weight of thermoplastic resin,wherein the continuous reinforcing fiber-impregnated prepreg layer (20) is prepared by drawing and pressing fibers passed through an impregnation die supplied with a thermoplastic resin melt and aligned the fibers two-dimensionally. Figure : 1
Full Text Technical Field
The present invention relates to a thermoplastic composite sheet comprising fiber impregnated prepreg layer manufacturing method and article manufactured thereof
Background Art
Japanese patent laid-open publication No. Hei 4-19935 discloses a process of forming decorative wood laminates, such as sheets, by impregnating fine wood and cellulose powder with urea resin, drying and neutralizing the impregnated material, and entraining the neutralized material into a thermoplastic resin. Also, the publication discloses a method of forming a decorative wood board with the desired shape by additionally processing the decorative laminate, sticking the processed decorative laminate to a pallet having a cut network section along the thickness direction thereof, and pressing the resulting structure. However, the panel product has problems in that it can be used in a given specification due to a hollow in the center thereof, and if a portion thereof is cut and used, it will show deterioration
in physical properties and a reduction in bending elastic
modulus as a function of density, so that it will be
unsuitable for use as a support for concentrated load.
Another problem is that its production process is
complicated.
Korean patent laid-open publication No. 96-443
discloses a form panel made of recycled resin, which is
prepared by extruding recycled gel-like resin in the form of
a plate, rolling the plate to the designed thickness while
cold forming the plate into the desired shape. However, this
product has problems in that it is heavy in weight, its
physical properties are determined depending on the kind and
composition of the recycled resin, and its production process
is complicated.
Regarding compound panels, Japanese patent laid-open
publication No. Hei 4-50900 discloses the technology of
foaming the center layer of a multi-layer structure. The
invention disclosed in this publication relates to an
industrial multi-layer panel excellent in thermal resistance,
impact resistance and rigidity, which is made of polyolefin,
such as polypropylene or polystyrene. This panel is
characterized by a multi-layer sheet of a glass fiberreinforced
resin composite, comprising a sheet layer of
thermoplastic resin containing 10-45% by weight of glass
short staple fibers, and a base sheet layer of expanded
thermoplastic resin containing 5-50% by weight of fine
inorganic powder and having a density of 0.4-l.llg/cm3.
However, this panel product has problems in that it is heavy
in weight and low in impact strength since its center layer
density and overall density are as high as 0.84-0.85g/cm3 and
1.75-1.76g/cm3, respectively.
Korean patent laid-open publication No. 2004-0003835
discloses panels capable of substituting for form panels for
use in the formation of concrete walls, temporary door frames
for wood door frames, stoppers and other plywood panels, as
well as a manufacturing method thereof. However, the
products disclosed in the publication are unsuitable for
recycling products laminated with plywood as the coated
products and shows a reduction in production efficiency upon
the application of a pressing process. Also, this invention
uses plywood, and thus, do not contribute to reduce the
consumption of natural resources.
Korean patent laid-open publication No. 10-2002-
0092590 discloses a synthetic resin panel manufactured from
wastes, such as waste plastic, waste cotton, waste leather,
waste wood, sawdust, etc., as main materials, as well as a
form panel manufactured therefrom. This invention uses a
glass fiber layer in which a continuous reinforcing fiber
layer is non-impregnated, and thus, is weak in strength and
interlayer adhesion. In addition, upon its use and cutting,
fiber dusts fly in all directions, thus causing~ damage to the
health of workers.
Korean patent laid-open publication No. 96-4300
discloses a multi-layer composite panel which has a hollow in
the center and can be used as a concrete form. This panel is
a five-layer panel manufactured by laminating a network fiber
material on a hollow center layer of a lattice structure and
sticking a foaming layer of composite resin on the laminated
fiber layer by heating. However, the composite panel
disclosed "in the publication shows low physical properties
since the adhesion between the resin layers is interfered by
the network fiber layer. Also, it is difficult to separate
the network fiber layer from the hollow center layer, in
recycling, and due to the center hollow, the panel is weak
against locally concentrated load or impact. Moreover, since
the continuous reinforcing fiber layer is a non-impregnated
glass fiber layer, it has no an effective reinforcing action
and also the adhesion between the layers is weakened. Also,
upon its use and cutting, fiber dusts fly in all directions,
thus causing damage to the health of workers.
Korean patent laid-open publication No. 10-2001-
0016955 discloses a multi-layer panel comprising a surface
layer treated with synthetic resin on both or single side
thereof, and a center layer made of a mixture of wood flour,
chaff powder and waste plastic resin. This panel is lighter
in weight than a multi-layer resin panel and satisfies the
requirements of both strength maintenance and water
tightness. However, it has no reinforcing fiber layer, and
thus, is insufficient in bending strength, physical
properties, linear thermal expansion coefficient, and impact
strength.
In addition, wood panels which are used for industrial
applications and as form panels in the constructional field
have not only limitation in their supply but also the risk of
damage to forests. For this reason, the development of a
substitute material for the wood boards now exists.
Accordingly, various plastic and synthetic resin-based panels
are currently developed. The common disadvantage of the
plastic panels is that the bending elastic modulus at
temperature of 30-60°C is low. Also, their liner thermal
expansion coefficient is generally as high as 1 x 10~/K, and
thus, if there is a great change in surrounding temperature,
the panels will encounter problems caused by their expansion
or shrinkage. Although these problems can be solved to some
extent by increasing the content of a filler and the like,
the increase in the filler content results in a reduction in
impact resistance and an increase in density leading to an
increase in weight, thus making the use of the panels
inconvenient. -These problems are caused by the intrinsic
properties of commercially available thermoplastic polymers,
and thus, unavoidable in products manufactured from such
materials. On the other hand, wood panels have a very low
thermal expansion coefficient of 1 x 105/K at a temperature
of 0-50 °C, and a high bending elastic modulus of 25,000-
50,000kg/cm2. Also, they show an insignificant reduction in
physical properties at high temperature and have a
lightweight corresponding to a density of 0.6-0.8g/on3.
However, the existing products fail to satisfy all such
requirements, and thus, cannot fully substitute for the
functions of wood panels.
In attempts to solve these problems, any of the
following 'methods as done in the prior art is used: (1) a
glass fiber-reinforced resin composite layer is used; (2) a
network sheet of glass fibers is laminated; (3) a composite
resin layer containing a significant amount of wood flour is
used; or (4) a wood board is coated with a certain material.
However, the method (1) provides a product reinforced with
short staple fibers, and thus, results in limitations in
improving bending strength and linear thermal expansion
coefficient. This limitation may also be overcome by
increasing the amount of reinforcing fibers or the aspect
ratio of fibers, but in which case manufacturing cost will be
increased. The method (2) including the use of the network"
layer of glass fibers hardly exhibits sufficient effects
since the impregnability of thermoplastic resin into glass
fibers is very poor. The method (3) including the use of a
large amount of wood flour and inorganic filler results in a
great reduction in material cost, but shows no. great effect
on the improvement of physical properties. Thus, this method
is generally used in combination with the method (1) The
method (4) cannot basically solve environmental burdens
caused by the use of wood boards, i.e., environmental
destruction caused by felling. Also, the method has the
problem of interlayer separation since the adhesion
compatibility between the wood board and the resin layer is
low.
Multi-layer panel products .including thermoplastic
polymer resin as a base resin mostly have a linear thermal
expansion coefficient of more than 8 x 10~5/K. For this
reason, there is a felt need for the development of
technology allowing shrinkage and expansion to be remarkably
low even in the case of a severe change in temperature, such
as the daily range of temperature, while making impact and
bending strength excellent.
For automobile parts, various composite resin
materials are now being developed to solve the problems of
cost and weight in the existing metal and steel materials.
Particularly, a compound material for a bumper back beam is
manufactured by the technology comprising laminating a glass
fiber mat, chopped fibers and thermoplastic polyolefin resin
(e.g., polypropylene) and melt-compressing the laminate to
prepare a glass mat thermoplastic (GMT) sheet, heating and
compression-molding the GMT sheet into the desired shape.
Although this technology provides relatively high specific
strength and impact strength, the method of making the GMT
sheet is a heat-compression method providing only incomplete
impregnation of the resin into the fibers. Thus, this
technology has problems in that not only a non-impregnated
portion of the fibers does not effectively contribute to
enhance the physical properties of the product, but also an
environmental problem, such as dropping of fibers onto
workers in drilling and bolting operations, is caused.
Also, since a simple structure, sufficient melting
time and compression time are required, in order to achieve
sufficient impregnation in the compression-molding process,
this technology has the problem of an increase in molding
time and cannot form ribs with various structures.
In addition to the GMT technology, there is suggested
a method of manufacturing completely impregnated long fiber
thermoplastic composite products by a pultrusion process.
However, the products manufactured by this method have a
problem in that they are insufficient in strength or cause
defects at welded lines, due to insufficient fiber length.
Disclosure of the Invention
Therefore, the present invention has been made to
solve the above-mentioned problems occurring in the prior
art, and it is an object of the present invention to provide
composite sheet which is excellent in not only mechanical
properties, such as bending strength, bending elastic
modulus, impact strength and linear thermal expansion
coefficient, but also secondary processability, and is
suitable for molding into various structures, such as panels
for use as building materials, and automobile parts, as well
as a manufacturing method thereof and an article manufactured
therefrom.
To achieve the above object, in one aspect, the
present .invention provides a composite sheet comprising: a
center layer of thermoplastic resin; and a continuous
reinforcing fiber-impregnated prepare layer laminated on at
least one surface of the upper and lower surfaces of the
center layer; the prepare layer comprising 5-65% by weight of
reinforcing fibers and 35-95% by weight of thermoplastic
resin.
In another aspect, the present invention provides a
method for manufacturing a composite sheet, the method
comprising the steps of: (i) melt-extruding thermoplastic
resin into a given shape to prepare a center layer; and (ii)
providing a continuous reinforcing fiber-impregnated prepreg
layer and compressing the prepares layer on at least one
surface of the center layer, the layer comprising 5-
65% by weight of reinforcing fibers and 35-95% by weight of
thermoplastic resin.
In still another aspect, the present invention
provides an article manufactured by molding the composite
sheet manufactured as the above described into a given shape
in a molding machine together with pellets comprising 10-60%
by weight of strength-reinforcing material and 40-90% by
weight of thermoplastic resin.
Alternatively, the above-described article, such as a
building material or an automobile part, may be manufactured
by molding a continuous reinforcing fiber-reinforced prepreg
alone or in combination with a GMT sheet into the desired
shape in a molding machine together with thermoplastic resin.
Also, the composite sheet may be formed into the
desired shape by press-molding it alone or in combination
with a GMT sheet after heating.
Brief Description of the Drawings
FIG. 1 is a perspective view showing a state where
layers forming a thermoplastic composite sheet according to
the present invention are separated from each other.
FIG. 2 is a perspective view showing a state where the
layers forming the thermoplastic composite sheet shown in
FIG. 1 are coupled to each other.
FIG. 3 schematically shows a side cross-sectional view
of a tape-shaped prepreg forming the prepreg layer of the
thermoplastic composite sheet shown in FIG. 1.
FIG. 4 is a perspective view showing that the
thermoplastic composite sheet being formed with holes which
are passed there through.
FIG. 5 is a side cross-sectional view schematically
showing a process for manufacturing a thermoplastic composite
sheet according to the present invention.
FIGs. 6 and 7 schematically show processes of using
the inventive thermoplastic composite sheet to form a
building material and an automobile part, respectively.
FIG! 8 is a graphic diagram for illustrating an
improvement in the physical properties of the thermoplastic
composite sheet being formed with holes as shown in FIG. 4.
FIGs. 9 and 10 schematically show processes of using a
continuous reinforcing fiber-impregnated prepreg included in
the inventive thermoplastic composite sheet to form a
building material and an automobile part, respectively.
FIGs. 11 and 12 schematically show processes of using
the inventive thermoplastic composite sheet in combination
with a GMT sheet to form a building material and an
automobile part, respectively.
FIGs. 13 and 14 schematically show processes of using
a continuous reinforcing fiber-impregnated prepreg included
in the inventive thermoplastic composite sheet in combination
with a GMT sheet to form a building material and an
automobile part, respectively.
Best Mode for Carrying Out the Invention
Hereinafter, preferred embodiments of the present
inventions will be described in detail with reference to the
accompanying drawings.
FIG. 1 is a perspective view showing a state where
layers forming a'thermoplastic composite sheet according to
the present invention are separated from each other, and FIG.
2 is a perspective view showing a state where the layers of
the thermoplastic composite sheet shown in FIG. 1 are coupled
to each other.
As can be seen in the drawings, the thermoplastic
composite sheet 1 according to a preferred embodiment of the
present invention comprises the melt-extruded center layer
10, the continuous reinforcing fiber-impregnated prepreg
layer 20 laminated on the upper and/or lower surface of the
center layer 10, and optionally, the protective layer 30
laminated on the continuous reinforcing fiber-impregnated
prepreg layer 20.
The center layer 10 may preferably be made from a
foaming layer and a fiber-reinforced thermoplastic resin. If
necessary, the center layer 10 made of fiber-reinforced
thermoplastic resin may also comprise 5-50% by weight of
reinforcing fibers with an average length of l-30mm, 15-30%
by weight of inorganic filler, or 20-40% by weight of wood
flour or chaff.
As shown in FIG. 1, the continuous reinforcing fiberimpregnated
prepreg layer 20 has a flat structure woven in
the form of the welt 20a and the warp 2 Ob or formed into a
bi-directional or uni-directional configuration where tapes
or strands are laminated on each other. Each of the tapes or
strands forming the continuous reinforcing fiber-impregnated
prepreg layer 20 comprise 5-65% by Weight of reinforcing
fibers with an average length of 5-30mm and 35-95% by weight
of thermoplastic resin: The thermoplastic resin may also
contain 0".2-5% by weight of inorganic fillers, such as
calcium carbonate, hallow beads, talc, mica, wollastonite,
zinc sulfide and activated carbon.
The reinforcing fibers contained in a uniform mixture
of thermoplastic resin and reinforcing fibers (i.e.,
continuous reinforcing fiber-impregnated prepreg layer 20},
are uniformly impregnated with thermoplastic resin while
forming continuous fiber bundles in a length direction.
Thus, these fibers can be two-dimensionally aligned in the
form of, for example, welts and warps, as desired, and can be
aligned to an unlimited extent in the transverse and
longitudinal directions of the panel.
The continuous reinforcing fiber-reinforced prepreg
layer 20 used in the present invention is formed in a tape or
strand shape by drawing and pressing fibers passed through an
impregnation die supplied with a thermoplastic resin melt.
The tape or strand so obtained has a thickness of about 0.4-
0.5mm and a width of about 5-12mm, and consists of about
5,000 fiber filaments. The impregnated prepreg forming the
continuous reinforcing fiber-impregnated prepreg layer 20 was
shown to have about 5-10 times higher tensile straight than a
general glass fiber composite material. The mechanical
properties of the formed prepreg tape or strand were measured
according to ASTM D3039, and the results are shown in Table 1
below. In this regard, the cross-head speed was 2mm/min, and
the gauge length was 150mm.
The protective layer 30 is optionally melted and
adhered to the continuous reinforcing fiber-impregnated
prepreg layer 20 by melt extrusion, in order to prevent the
continuous reinforcing fiber-impregnated prepreg layer. The
protective layer 30 is a thermoplastic resin layer, a foamed
thermoplastic resin layer or a fiber-reinforced thermoplastic
resin layer and comprises 0-54% by weight of reinforcing
fibers arid 46-100% by weight of thermoplastic resin. In this
regard, the thermoplastic resin may also contain 0.2-5% by
weight of inorganic fillers, such as such as calcium
carbonate, hallow beads, talc,, mica, wollastonite, zinc
sulfide and activated carbon.
The reinforcing fibers used in the center layer 10,
the continuous reinforcing fiber-reinforced prepreg layer 20
and the protective layer 30 may be selected from the group
consisting of glass fibers, aramid fibers, natural fibers,
polyester fibers, polyamide fibers, and a mixture thereof.
The thermoplastic resin may be selected from the group
consisting of polypropylene, polyethylene, polyamide,
polyester and polyphenylene sulfide resins, and a mixture
thereof.
The thermoplastic composite sheet according to an
embodiment of the present invention is manufactured in the
following manner.
As shown in FIG. 5, a uniform mixture of thermoplastic
resin and glass fibers, which has been subjected to an
impregnation process, is molded in the form of a tape or a
strand. Then, the tapes or strands are woven or laminated to
prepare the continuous reinforcing fiber-impregnated prepreg
20 with a thickness of 0.4-0.9mm, which has the welt 20a and
the warp 20b, and then the impregnated prepreg 20 is wound
around the rollers 2la and 21b.' The impregnated prepregs 20
wound around the rollers 2la and 21b are disposed on the
upper surface and/or lower surface of the center layer 10
extruded from a center layer extruder 31, respectively.
As described above, the center layer 10 may contain
wood flour or chaff or may be made of a foam material. If
the center layer 10 contains wood flour or chaff, 20-40% by
weight of waste wood flour or chaff with a particle size of
less than 25 meshes and a water content of less than 4% will
be mixed with 60-80% by weight of polypropylene, and then
extruded through the extruder 31 in a state where the mixture
has been heated to a temperature of 160-200°C. Also, if the
center layer 10 is made by foaming, 0.2-5% by weight of an
inorganic "or organic foaming agent, and preferably, a 1:1
mixture of NaHCOs with citric acid, or azo dicarbonamide,
will be uniformly mixed with propylene resin, and the mixture
will be heated to a temperature of 160-200°C and formed into
the desired shape through the extruder 31. Also, the center
layer 10 may be obtained by extruding a long fiber-reinforced
composite material or a composite material through the
extruder 31, in the same manner as described above. Also, the
center layer 10 may be obtained by mixing recycled
polyethylene powder resin with 1-4% by weight of a pigment
with the desired color and extruding the mixture at a
temperature of 150-190°C, in the extruder 31.
The continuous reinforcing fiber-impregnated prepreg
20 is passed through the protective layer die 32 together
with the center layer 10 in the moving direction of the
center layer 10 extruded from the extruder 31, during which
it is continuously formed on the upper surface, and/or lower
surface of the center layer 10. The center layer 10 and
continuous reinforcing fiber-iinpregnated prepreg layer 20
passed through the protective layer die 32 are planarized by
the upper and lower compression rolls 33 disposed adjacent to
the outlet of the die 32, and then, cooled while they are
passed through the cooling unit 34. Unlike the prior method
including a discontinuous process, such as pressing or
stamping, the inventive process can simply control the postcooling
deformation of the thermoplastic composite sheet and
can show a" great increase in production efficiency.
The protective layer 30 which is melted and adhered on
the continuous reinforcing fiber-reinforced prepreg layer 20
to a thickness of 0.5-3mm is extruded from the protective
layer die 32 to the continuous reinforcing fiber-reinforced
prepreg layer 20 laminated on both surfaces of the center
layer 10, and compressed to a given thickness, for example,
l-3mm, by the compression rolls 33, so that the inventive
thermoplastic composite sheet can be made in a multi-layer
structure. The protective layer 30 is melted and adhered on
the continuous reinforcing fiber-reinforced prepreg layer 20,
and compressed on the prepreg layer 20 by the compression
rolls 33 and then cooled by the cooling unit 34, thus
preparing a molded flat material with a multi-layer
structure. The cooled molded material can be withdrawn by
withdrawing rolls (not shown) and cut into a given size by
means of a cutter.
Meanwhile, the thermoplastic composite sheet according
to the present invention may also be produced in the form of
either a constructional board with a smooth surface or a
board having various patterns formed thereon, depending on
the surface patterns of the compression rolls 33 after the
protective layer 30 has been melted and adhered on the
continuous reinforcing fiber-impregnated prepreg layer 20 but
before the cooling process.
Example 1
According to the inventive method as described above,
a fiber-reinforced continuous prepreg tape having a thickness
of 0.25mm and a width of 25mm is obtained by impregnating 40%
by weight of glass fiber with thermoplastic polypropylene
resin, a 4mm-thick prepreg sheet was manufactured by weaving,
or laminating the fiber-reinforced continuous prepreg tape in
order to use in manufacturing of a thermoplastic composite
sheet. The sheet was measured for bending strength, sheet
impact strength and Izod impact resistance, and the results
are shown in Table 2 below.
Comparative Example 1
A 4mm-thick composite sheet was manufactured from a
mixture of polypropylene-based resin and 40% .by weight of
glass fibers by the prior GMT process and measured for
bending strength, sheet impact strength and Izbd impact
strength, and the results are shown in Table 2 below.
(Table Removed)
As can be seen in Table 2, all the mechanical
properties of the prepreg sheet woven or laminated with the
thermoplastic prepreg tape according to the present invention
were two times higher than those of a non-impregnated sheet.
In the case of GMT, if the time of heat-compression was made
very long, a slight improvement over the above-described
physical properties could be achieved but the process time
would be at least two times longer than Example 1.
Example 2
According to the inventive method as described above,
a prepreg layer woven or laminated with a continuous fiber
prepreg tape having a thickness of 0.25mm and a width of
25mm, obtained by impregnating 40% by weight of glass fibers
with thermoplastic polypropylene resin, was laminated in two
layers on each of both sides of linm-thick center layers made
of a long fiber-resin composite, thus manufacturing a
laminated sheet with a total thickness of 3mm. The sheet was
measured for bending strength, sheet impact strength and Izod
impact strength, and the results are shown in Table 3 below.
Comparative Example 2-1
According to the prior GMT process, a 4ram-thick
composite sheet made of polypropylene-based resin and 40% by
weight of glass fibers was melt-pressed to a thickness of 3mm
at 230°C such that the largest possible amount of
polypropylene could be penetrated between the glass fibers.
The melt-pressed sheet was measured for bending strength,
sheet impact strength and Izod impact strength, and the
results are shown in Table 3 below.
Comparative Example 2-2
A 3mm-thick injected sample consisting of only a
discontinuous long fiber-resin composite sheet obtained by
impregnating 40% by weight of glass fibers with thermoplastic
polypropylene resin was manufactured and measured for bending
strength, sheet impact strength and Izod impact strength.
The results are shown in Table 3.
As can be seen in Table 3, in case the long fiberresin
composite was used at the center layer, also Example
has excellent mechanical properties in comparison with the
prior GMT and the discontinuous long fiber-resin composite
sheet of Comparative Example 2-2.
(Table 3)
(Table Removed)
Example 3
According to the inventive method as described above,
the continuous reinforcing fiber-impregnated prepreg layer 20
with a thickness of 0.5mm was woven or laminated with a
reinforcing fiber-impregnated prepreg tape with a thickness
of 0.25mm and a width of 25mm, which has been obtained by
impregnating thermoplastic polypropylene resin into glass
fibers. The prepreg layer 20 was laminated in one layer on
each of both sides of the lOmm-thick center layer 10
consisting of a composite layer of 40% by weight of chaff and
polypropylene resin. Between the center layer 10 and the
continuous reinforcing fiber-impregnated prepreg layer 20, a
0. 5mm-thick polypropylene adhesive layer was provided and the
layers were melt-adhered to each other, thus manufacturing a
laminated sheet with a thickness of 12mm. The sheet was
measured for bending strength, sheet impact strength and Izod
impact strength, and the results are shown in Table 4 below.
Comparative Example 3-1
A 2mm-thick layer made of only thermoplastic
polypropylene resin (MI 0.5g/dmin, a block copolymer) was
formed on both sides of the lOmm-thick center layer made of a
composite of 40wt% of chaff and polypropylene resin, thus
manufacturing a 12mm-thick laminated sheet. The sheet was
measured for bending strength, sheet impact strength and Izard
impact strength, and the results are shown in Table 4 below.
Comparative Example 3-2
A 2itm-thick layer made of a composite obtained by
impregnating polypropylene into 20% by weight of glass fibers
was formed on both sides of the 8mm-thick center layer made
of a composite of 40wt% of chaff and polypropylene resin,
thus manufacturing a 12mm-thick laminated sheet. The sheet
was measured for bending strength, sheet impact strength and
Izod impact strength, and the results are shown in Table 4.
Comparative Example' 3-3
A 1 mm-thick layer made of only thermoplastic
polypropylene resin (MI 0.5 g/dmin, block copolymer) was
formed on both sides of the 9.5mm-thick center layer made of
a composite of 40wt% of chaff and polypropylene resin.
Between the center layer and both outer layers, a network
woven sheet woven with glass fibers was inserted and the
layers were compressed through compression rolls at 200°C,
thus manufacturing a 12mm-thick laminated sheet. The sheet
was measured for bending strength, sheet impact strength and
Izod impact strength, and the results are shown in Table 4,
(Table Removed)
As can be seen in Table 4, Example 3 including the
continuous reinforcing fiber-impregnated prepreg layer was
excellent in physical properties even at the same glass fiber
content as compared to Comparative Example 3-3 including the
non-impregnated fiber layer. Also, Example 3 showed
significantly excellent physical properties as compared to
Comparative Example 3-1 having no glass fiber-reinforced
layer and Comparative Example 3-2 formed by the extrusion of
cut fibers. In the case of Comparative Example 3-2, the
overall glass fiber content was 6.7wt% reaching two times
that of Comparative Example 3, but showed a reduction in
physical "properties. This' is thought to be because
discontinuous short fibers were used and the thickness
distribution of the outer layers in the extrusion was not
uniform. Extended fibrous fluid has a phenomenon where it is
un mixed into other layers in a multilayer formation
process, and this phenomenon becomes severe with an increase
in the fiber length and a reduction in the fiber viscosity.
Example 4
On each of both sides of the center layer 10
consisting of a 9mm-thick polypropylene resin layer expanded
to a density of 0.4g, a polypropylene layer with a thickness
of 1mm was formed. Then, on both sides of the center layer,
a O.Smm-thick sheet woven with a 0.25mm-thick and 25mm-wide,
continuous reinforcing fiber-impregnated prepreg tape formed
by impregnating thermoplastic polypropylene resin into 40wt%
of glass fibers as described above was melt-laminated in one
layer, thus manufacturing a laminated sheet with an overall
thickness of 12mm. The sheet was measured for bending
strength, bending elastic modulus and Izod impact strength,
and the results are shown in Table 5 below.
Comparative Example 4
On both sides of the center layer 10 consisting of a
Sram-thick "polypropylene resin layer expanded to a density of
0.4g/cc, a 2mm-thick layer consisting of only a glass fiberresin
composite layer formed by impregnating thermoplastic
polypropylene resin into 30wt% of glass fibers was meltlaminated,
thus manufacturing a laminated sheet with an
overall thickness of 12mm. The sheet was measured for
bending strength, bending elastic modulus and Izod impact
strength, and the results are shown in Table 5.
(Table 5)
(Table Removed)
As can be seen in Table 5, even though Example 4 had a
lower glass fiber content than that of Comparative Example 4,
it showed improvements in impact strength, linear thermal
expansio'n coefficient and the like, and similar bending
elastic modulus, as compared to Comparative Example 4. Also,
Example 4 was lighter in weight, as the use amount of glass
fibers was reduced, leading to a reduction in density.
The inventive thermoplastic composite sheet 1 as
described above can be used to manufacture building forms or
automobile parts, such as automobile bumper back beams.
If the inventive thermoplastic composite sheet 1 is
formed into a panel for use as a building material, the
thermo plastic composite sheet 1 is then placed in the molding
machine 41 as shown in FIG. 5. Then, pellets comprising
about 10-60% by weight of reinforcing fibers with a length of
less than 30mm and about 40-90% by weight of thermoplastic
resin containing an inorganic filler and a pigment were
introduced into the molding machine 41 and molded into the
given shape, thus making the molded article 44, such as a
lighter-weight and higher-strength panel for use as a
building material. Molding methods which can be used to form
the inventive thermoplastic composite sheet 1 into a panel
for use as a building material, such as a form include high pressure
injection, low-pressure injection, such as
compression molding after extrusion or compression molding
after injection, and press molding after heating.
Meanwhile, although the inventive thermoplastic
composite sheet 1 can be manufactured in a size of 1200mm x
1200mm, the thermoplastic composite sheet 1 with a larger
size can be made by making the panels 1 with a smaller size,
overlapping the edges of the panels 1 with each other, and
heating and melting the resin contained in the panels 1 so as
to connect the panels with each other.
If the thermoplastic composite sheet 1 according to
the present invention is used to manufacture an automobile
part, such as a bumper back beam, the thermoplastic composite
sheet cut into a given size is then preformed into the
preform 42 with a given shape as shown in FIG. 7. The
preform 42 is placed in the molding machine 41, and formed
into a given shape together with pellets comprising about 10-
60% by weight of reinforcing fibers with a length of less
than 30mm and about 40-90% by weight of thermoplastic resin
containing an inorganic filler and a pigment, as done in the
case of making the molded article 44, such as a panel for use
as a building material, for example, a form. This gives the
molded article 43 with lighter weight and higher strength,
such as an automobile part.
In order to make a form or an automobile part, the
thermoplastic composite sheet 1 according to the present
invention may be placed in the molding machine 1 in a state
where holes or slits 45 have been formed through the panel 1
as shown in FIG. 4 (only holes are shown in the drawing). As
can be seen from a graph shown in FIG. 8, the form or
automobile part obtained in this case showed an increase of
about 30% in physical properties as compared to the case of
using the panel having no holes or slits.
If the thermoplastic composite sheet 1 manufactured by
the present invention is used as a preform for industrial
structures, such as forms or automobile parts, it will be
excellent in impregnability with reinforcing fibers, unlike
the prior art. Thus, a structure can be obtained, which has
overcome the phenomenon of lack of glass fibers occurring
often in the corners of a molded article, such as a form or
an automobile part, and has been suitably reinforced with the
continuous reinforcing fiber-impregnated prepreg.
The present invention allows the thermoplastic
composite sheet to be easily formed by a continuous process
as described above and can solve the above-described problems
by extruding the long fiber-thermoplastic resin composite
material as the center material. The panel thus formed has a
compromise between the advantages and disadvantages of the
continuous reinforcing fiber-impregnated prepreg and the long
fiber-resin composite, and thus, can provide a remarkable
reduction in variation in physical properties between varying
portions of a secondary processed products by compressionmolding
According to the present invention, the building
material and automobile part as described above can be
manufactured by molding the thermoplastic composite sheet 1
into a given shape in the molding machine 41. Alternatively,
as shown in FIG. 9, the building material or the automobile
part may also be manufactured by placing the continuous
reinforcing fiber-impregnated prepreg layer 20 in the mold 41
and then performing the molding process as described above.
In anther alternative embodiment as shown in FIG. 10, the
building material or the automobile part may be manufactured
by placing in the mold 41 the continuous reinforcing fiber impregnated
prepreg layer 20 preformed into a given shape,
and then performing the molding process as described above.
In "other alternative embodiments, an article having
the same effect as the above-described article, such as a
building material or an automobile part, may be manufactured
by molding the GMT sheet 46 in combination with the inventive
thermoplastic composite sheet 1 as shown in FIGs. 11 and 12,
or by molding the GMT sheet 46 in combination with the
continuous reinforcing fiber-reinforced prepreg layer 20 as
shown in FIGs. 13 and 14.
In still another alternative embodiment, the inventive
thermoplastic composite sheet 1 as described above may be
simply heated and then pressed-molded into a given shape,
thus manufacturing articles, for example, a panel for use as
a building material, such as a form, or an automobile part,
such as a back beam.
Industrial Applicability
As described above, the present invention provides the
technology allowing the industrial thermoplastic composite
sheet with high mechanical strength and no scattering of
fibers to be produced in high productivity and a costeffective
manner. The inventive thermoplastic composite
sheet can be used as an excellent plywood substitute which is
low in cost, very high in bending strength and impact
strength, and remarkably low in linear thermal expansion
coefficient as compared to the prior product, leading to a
reduction in thermal deformation caused by the daily range of
temperature.
Also, the present invention provides the method
allowing the continuous reinforcing fiber-impregnated prepreg
to be effectively used. The suitable use of an extrusion
process in the present invention allows post-cooling
deformation to be simply controlled and production efficiency
to be highly increased, unlike the prior method including
pressing or stamping, since the continuous reinforcing fiber impregnated
layer is continuously formed and subjected to an
in-line cooling process simultaneously to the center layer.
Also, the thermoplastic composite sheet according, to
the present invention is manufactured by melt-extruding the
center layer consisting of a "layer formed by melting of
completely impregnated long fiber thermoplastic (LET)
pellets, an inorganic filler-resin composite layer, an
expanded layer, or a wood flour-resin composite layer, and
3/
then sticking a continuous prepreg' on the upper surface
and/or lower surface of the center layer. Thus, if the
inventive thermoplastic composite sheet is used as a preform
for forming industrial structures, a structure can be
obtained, which is excellent in impregnability with glass
fibers, has overcome the phenomenon of lack of glass fibers
occurring often in the corners of a molded article, and has
been suitably reinforced with the continuous reinforcing
fiber-impregnated prepreg.
Furthermore, the present invention provides a
reinforced composite resin panel by molding a layer woven or
laminated with a continuous reinforcing fiber-impregnated
prepreg, into a given shape in combination with a layer
formed by melting of completely impregnated long fiber
thermoplastic pellets, an inorganic filler-resin composite
layer, an expanded layer, or a wood flour-resin composite
layer. The inventive thermoplastic composite sheet can be
used as an excellent plywood substitute which is low in cost,
very high in bending strength (more than 30000kgf/cm2) and
impact strength, and remarkably low in linear thermal
expansion coefficient as compared to the prior product,
leading to a reduction in thermal deformation caused by the
daily range of temperature.
In addition, the inventive thermoplastic composite
sheet may also be subjected to a secondary processing process
by melt compression, in which case structures with light
weight and high mechanical properties can be formed
various shapes, and flat products required therefor can be
produced.
Although a preferred embodiment of the present
invention has been described for illustrative purposes, those
skilled in the art will appreciate that various
modifications, additions and substitutions are possible,
without departing from the scope and spirit of the invention
as disclosed in the accompanying claims.










We claim,
1. A thermoplastic composite sheet (1) comprising:
a center layer (10) made of a thermoplastic composite material containing thermoplastic resin; and
a continuous reinforcing fiber-impregnated prepreg layer (20) laminated on at least one surface of the upper surface and lower surface of the center layer (10), the prepreg layer (20) comprising 5-65% by weight of reinforcing fibers and 35-95% by weight of thermoplastic resin,
wherein the continuous reinforcing fiber-impregnated prepreg layer (20) is prepared by drawing and pressing fibers passed through an impregnation die supplied with a thermoplastic resin melt and aligned the fibers two-dimensionally .
2. The thermoplastic composite sheet (1) as claimed in Claim 1, wherein the center layer (10) comprises 5-50% by weight of reinforcing fibers with an average length of 1-30 mm.
3. The thermoplastic composite sheet (1) as claimed in Claim 1, wherein the center layer (10) comprises 15-30% by weight of inorganic filler.
4. The thermoplastic composite sheet (1) as claimed in Claim 1, wherein the center layer (10) comprises at least one of 20-40% by weight of wood flour and chaff.
5. The thermoplastic composite sheet (1) as claimed in Claim 1,wherein the composite sheet comprises a protective layer (30) melted and adhered on the continuous reinforcing fiber-impregnated prepreg layer (20), the protective layer
(30) comprising 0-54% by weight of reinforcing fiber and 46-100% by weight of thermoplastic resin.
6. The thermoplastic composite sheet (1) as claimed in Claim 1 or 5, wherein the center layer (10) is a foaming layer or a glass fiber-reinforced thermoplastic resin layer.
7. The thermoplastic composite sheet (1) as claimed in Claim 1 or 5, wherein the thermoplastic resin is selected from the group consisting of polypropylene, polyethylene, polyamide, polyester, and polyphenylene sulfide resins, and a mixture thereof.
8. The thermoplastic composite sheet (1) as claimed in Claim 2, wherein the reinforcing fibers are selected from the group consisting of glass fibers, aramid fibers, natural fibers, polyester fibers, polyamide fibers, and a mixture thereof.
9. The thermoplastic composite sheet (1) as claimed in Claim 3, wherein the inorganic filler is selected from the group consisting of calcium carbonate, hollow beads, talc, mica, wollastonite, zinc sulfide, activated carbon, and a mixture thereof.

10. The thermoplastic composite sheet (1) as claimed in Claim 1 or 5, wherein the continuous reinforcing fiber-impregnated prepreg layer (20) has a bi-directional or mono-directional structure.
11. A method for manufacturing a thermoplastic composite sheet (1) as claimed in claim 1, wherein the method comprising the steps of:
(i) melt-extruding a thermoplastic composite material comprising thermoplastic resin to prepare a center layer (10) made of the thermoplastic composite material;
(ii) providing a continuous reinforcing fiber-impregnated prepreg layer (20)comprising 5-65% by weight of reinforcing fibers and 35-95% by weight of thermoplastic resin and compressing the prepreg layer on at least one surface of the center layer (10) .
(iii) melt-extruding a mixture of 0-54% by weight of reinforcing fiber and 46-100% by weight of thermoplastic resin onto the continuous reinforcing fiber-impregnated prepreg layer (20) so as to form a protective layer (30) on the prepreg layer (20) .
12. The method as claimed in Claim 11, wherein the center layer (10) is a foaming layer or a glass fiber-reinforced thermoplastic resin layer.
13.The method as claimed in Claim 11, wherein the thermoplastic resin is selected from the group consisting of polypropylene, polyethylene, polyamide, polyester, and polyphenylene sulfide resins, and a mixture thereof.
14. The method as claimed in Claim 11, wherein the reinforcing fibers are selected from the group consisting of glass fibers, aramid fibers, natural fibers, polyester fibers, polyamide fibers, and a mixture thereof.
15. The method as claimed in Claim 11, wherein the inorganic filler is selected from the group consisting of calcium carbonate, hollow beads, talc, mica, wollastonite, zinc sulfide and activated carbon.
16. The method as claimed in Claim 11, wherein the
continuous reinforcing fiber-impregnated prepreg layer (20)
has a bi-directional or mono-directional structure.
17. An article manufactured by molding the thermoplastic
composite sheet (1) as claimed in claim 1 into the desired
shape in a molding machine together with pellets comprising
10-60% by weight of strength-reinforcing material and 40-90%
by weight of thermoplastic resin.
18. The article as claimed in Claim 17, wherein the thermoplastic composite sheet (1) is placed in the molding machine after preformed into the desired shape.
19. The article as claimed in Claim 17, wherein the strength-reinforcing material is a reinforcing fiber with a length of less than 30 mm, which is selected from the group consisting of glass fiber, aramid fiber, natural fiber, polyester fiber, polyamide fiber and a mixture thereof.
20. The article as claimed in Claim 17, wherein the strength-reinforcing material is selected the group consisting of calcium carbonate, hollow beads, talc, mica, wollastonite, zinc sulfide, activated carbon, and a mixture thereof.
21. The article as claimed in Claim 17, wherein the thermoplastic composite sheet (1) is partially drilled or slitted.
22. The article as claimed in Claim 17, which is molded
by a low-pressure injector.
23. An article manufactured by heat-melting the
thermoplastic composite sheet (1) as claimed in claim 1 and then press-molding the heated material in a mold at a lower temperature than the melting point thereof.
24. The article as claimed in Claim 17, wherein the article may be optionally a building panel or an automobile bumper back beam.

Documents:

5453-DELNP-2006-Abstract-(21-09-2010).pdf

5453-delnp-2006-abstract.pdf

5453-DELNP-2006-Claims-(21-09-2010).pdf

5453-delnp-2006-claims.pdf

5453-DELNP-2006-Correspondence-Others-(21-09-2010).pdf

5453-delnp-2006-correspondence-others.pdf

5453-DELNP-2006-Description (Complete)-(21-09-2010).pdf

5453-delnp-2006-description (complete).pdf

5453-DELNP-2006-Drawings-(21-09-2010).pdf

5453-delnp-2006-drawings.pdf

5453-DELNP-2006-Form-1-(21-09-2010).pdf

5453-delnp-2006-form-1.pdf

5453-delnp-2006-form-18.pdf

5453-DELNP-2006-Form-2-(21-09-2010).pdf

5453-delnp-2006-form-2.pdf

5453-delnp-2006-form-26.pdf

5453-DELNP-2006-Form-3-(21-09-2010).pdf

5453-delnp-2006-form-3.pdf

5453-delnp-2006-form-5.pdf

5453-DELNP-2006-GPA-(21-09-2010).pdf

5453-delnp-2006-pct-101.pdf

5453-delnp-2006-pct-210.pdf

5453-delnp-2006-pct-304.pdf

5453-delnp-2006-pct-311.pdf

5453-delnp-2006-pct-409.pdf

5453-delnp-2006-pct-416.pdf

5453-DELNP-2006-Petition 137-(21-09-2010).pdf


Patent Number 248413
Indian Patent Application Number 5453/DELNP/2006
PG Journal Number 28/2011
Publication Date 15-Jul-2011
Grant Date 13-Jul-2011
Date of Filing 20-Sep-2006
Name of Patentee SAMBARK CO., LTD.
Applicant Address SINHANG-RI 57-3, DUNPO-MYEON, ASAN-SI, CHUNGCHEONGNAM-DO 336-873, REPUBLIC OF KOREA
Inventors:
# Inventor's Name Inventor's Address
1 YOUN, SANG JUN #2-1104 MORAN APT., SSANGYONG-DONG 653, CHEONAN-SI, CHUNGCHEONGNAM-DO 330-090, REPUBLIC OF KOREA
2 JEONG, HO GAB #3-1003 MORAN APT., SSANGYONG-DONG 653, CHEONAN-SI, CHUNGCHEONGNAM-DO 330-090 REPUBLIC OF KOREA
PCT International Classification Number B32B 27/02
PCT International Application Number PCT/KR2005/001250
PCT International Filing date 2005-04-29
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 10-2004-0030641 2004-04-30 Republic of Korea