U.S. patent application number 14/895815 was filed with the patent office on 2016-04-21 for spray-coating method.
This patent application is currently assigned to HP PELZER HOLDING GMBH. The applicant listed for this patent is HP PELZER HOLDING GMBH, KRAUSSMAFFEI BERSTORFF GMBH. Invention is credited to Thomas Karcz, Sergej Kohlert, Joachim Meyke, Norbert Nicolai, Toni Nippe, Holger Schaarschmidt, Volkmar Schulze, Christian Urban.
Application Number | 20160108511 14/895815 |
Document ID | / |
Family ID | 50736053 |
Filed Date | 2016-04-21 |
United States Patent
Application |
20160108511 |
Kind Code |
A1 |
Nicolai; Norbert ; et
al. |
April 21, 2016 |
SPRAY-COATING METHOD
Abstract
A method for spray-coating substrate surfaces, in which (a) a
thermoplastically processable material is molten and thus liquefied
in an extruder in a first step; (b) the molten material is
pressurized by means of a carrier gas or vapor; (c) a mixture
formed from said molten material and said carrier gas or vapor is
pressed through one or more nozzles, optionally supplying a
spraying gas having a temperature at least as high as the melt
temperature to the spraying jet in the region of the discharge
opening of the nozzle; and (d) the obtained spray jet with the
molten material is directed onto the substrate surface, wherein the
material impinges in drops in a flowable state onto the substrate
surface, forms a continuous coating on the substrate surface, and
subsequently solidifies.
Inventors: |
Nicolai; Norbert;
(Schermbeck-Gahlen, DE) ; Schulze; Volkmar;
(Schierling, DE) ; Karcz; Thomas; (Dortmund,
DE) ; Kohlert; Sergej; (Witten, DE) ; Meyke;
Joachim; (Hannover, DE) ; Schaarschmidt; Holger;
(Achim, DE) ; Nippe; Toni; (Hannover, DE) ;
Urban; Christian; (Hannover, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
HP PELZER HOLDING GMBH
KRAUSSMAFFEI BERSTORFF GMBH |
Witten
Hannover |
|
DE
DE |
|
|
Assignee: |
HP PELZER HOLDING GMBH
Witten
DE
|
Family ID: |
50736053 |
Appl. No.: |
14/895815 |
Filed: |
May 6, 2014 |
PCT Filed: |
May 6, 2014 |
PCT NO: |
PCT/EP2014/059180 |
371 Date: |
December 3, 2015 |
Current U.S.
Class: |
427/447 |
Current CPC
Class: |
B05D 1/02 20130101; C23C
4/12 20130101 |
International
Class: |
C23C 4/12 20060101
C23C004/12 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 5, 2013 |
DE |
10 2013 208 235.5 |
Claims
1. A method for spray-coating substrate surfaces, in which (a) a
thermoplastically processable material is molten and thus liquefied
in an extruder in a first step; (b) the molten material is
pressurized by means of a carrier gas; (c) a mixture formed from
said molten material and said carrier gas is pressed through one or
more nozzles, supplying a spraying gas having a temperature at
least as high as the melt temperature to the spraying jet in the
region of the discharge opening of the nozzle; and (d) the obtained
spray jet with the molten thermoplastically processable material is
directed onto the substrate surface, wherein the material impinges
in drops in a flowable state onto the substrate surface, forms a
continuous coating on the substrate surface, and subsequently
solidifies.
2. The process according to claim 1, characterized in that said
thermoplastically processable material is selected from
homopolymers, co- and terpolymers or thermoplastically processable
elastomers, especially acrylonitrile-butadiene-styrene (ABS),
polyamide (PA), polylactate (PLA), polymethyl methacrylate (PMMA),
polycarbonate (PC), polyethylene terephthalate (PET), polyethylene
(PE), polypropylene (PP), polystyrene (PS), polyether ether ketone
(PEEK) and polyvinyl chloride (PVC) including copolymers and
compounds thereof, which may optionally contain further components,
especially fillers.
3. The process according to claim 1 characterized in that an amount
of fillers of from 0 to 80% by weight is employed, based on the
thermoplastically processable material.
4. The process according to claim 3, characterized in that said
filler is inorganic in nature.
5. The process according to claim 3 characterized in that said
filler is in the form of an inorganic short fiber.
6. The process according to claim 3 characterized in that said
filler has polymeric fibers having a melting temperature higher
than the processing temperature of the compound.
7. The process according to claim 3 characterized in that said
filler comprises natural fibers.
8. The process according to claim 2 characterized in that the
mixture, the thermoplastically processable material and/or the
filler itself as well as the weight ratio of thermoplastically
processable material to filler is varied in the course of the
spraying process.
9. The process according to claim 1 characterized in that nitrogen,
carbon dioxide or air is employed as the carrier gas and/or spray
gas.
10. The process according to claim 1 characterized in that a
spraying jet with a weight ratio of thermoplastically processable
material to carrier gas within a range of from 100:0.1 weight parts
to 100:30 weight parts is employed.
11. The process according to claim 1 characterized in that a
spraying jet with a pressure of from 10 to 500 bar is employed.
12. The process according to claim 1 characterized in that from 1
to 50 nozzles with different output cross-sectional areas are
employed.
13. The process according to claim 1 characterized in that said
mixture is pressed through orifice and/or slotted nozzles.
14. The process according to claim 1 characterized in that orifice
nozzles with the same or different diameters within a range of from
0.1 mm to 10 mm, or discharge openings with comparable
cross-sectional areas are employed.
15. The process according to claim 1 characterized in that slotted
nozzles with the same or different cross-sectional areas of 0.1 to
3 mm.times.3 to 30 mm are employed.
16. The process according to claim 1 characterized in that a
continuous coating that is porous or coherent in itself is
prepared.
17. The process according to claim 1 characterized in that a
substrate selected from textiles or a mold cavity with or without a
surface structure is employed.
Description
FIELD OF THE INVENTION
[0001] The invention concerns a method for spray-coating substrate
surfaces which enables different thermoplastically processable
materials to be applied to very different types of surfaces by
means of spray technology.
BACKGROUND
[0002] Very different types of methods are known for the
preparation of thin-walled sheet-like components or, for example,
insulations on textiles. Depending on the application, these
methods differ in shape quality, material, thickness distribution
over the substrate (component), and the technology itself
[0003] Known methods include these of deep-drawing, vacuum deep
drawing and pressing for the processing of sheets into formed parts
or individual layers.
[0004] In the production of sheet-like components by means of such
methods, the local mass distribution is determined by the
deformation of the sheet and cannot be set in a defined way. For
this reasons, for example, thus produced insulations are heavier
than necessary from a functional acoustic point of view. This
prevents the sought lightweight construction especially in
vehicles.
[0005] For material sealing, sheets are applied to very different
types of substrates by adhesive or hot-melt bonding.
[0006] For partial sound insulation, from an acoustic point of view
so-called heavy layer sheets are placed on carpet or bulkhead
zones, where they are attached by adhesive or hot-melt bonding.
[0007] Other methods are known for producing thin sheet-like
components for motor vehicles, such as heavy layer components for
acoustic insulation components, including bulkheads, produced by
injection molding of thermoplastic and thermosetting materials.
[0008] Injection molding (thermoplastic injection molding or
reaction injection molding (RIM)) allows components with different
defined masses per unit area to be produced. Because of the high
investment in the plants and molds, high quantities must be
produced by these methods.
[0009] For the RIM method, there is the additional problem that the
material to be employed, for example, polyurethane, is expensive
and cannot be recycled. Especially for insulation components in
vehicles, the mass distribution for all superstructures is
determined by the mold geometry. This also prevents the purposeful
acoustic optimization of individual vehicle types (engine versions)
within a series, which would be desirable in acoustic terms.
[0010] Further, methods for producing such sheet-like components by
the sintering of powder are known. The powder is applied to a warm
molding tool, where it forms a plastic layer by sintering, followed
by cooling and withdrawing the component. This technology is
intensive in time, tools and energy. Thus, this method remains
limited to the production of high-quality components, such as
slush-molded skins.
[0011] Methods for the coating as well as production of sheet-like
components by spraying are known. The spraying of thermoplastic
materials is effected either from a melt by means of one or more
nozzles, or via a "cold" plastic powder by means of heating above a
flame during the flight phase and a carrier gas, or directly by hot
surroundings during the flight phase. However, these methods have
very low throughputs and are only conditionally suitable for the
coating of substrates, i.e., only for temperature-resistant ones.
In the coating of textiles, the high temperatures would destroy the
textile material before application is completed.
[0012] The spray method also finds application in powder
regeneration. DE 10 2005 050 890 A1 describes a method and device
for producing a nanocomposite in which the separation of extractant
and dispersant, if any, from a polymer melt is effected by a high
pressure spraying method. In this method, the polymer droplets
solidify abruptly as a consequence of the rapid cooling taking
place in the relaxation of the high pressure level to environmental
pressure. This generates the nanocomposites.
[0013] As a heavy layer for spraying, cross-linking PUR-based
systems are employed. Details are found in DE 101 61 600 A1 and DE
10 2005 058 292 A1. These materials are very expensive and cannot
be recycled.
[0014] Further, methods and devices are known in which a plastic
bead is laid onto a, mostly pretreated, substrate surface. EP 0 524
092 B2 describes a method and device for producing an article with
a profiled cord. The profiled cord is produced by an extrusion die
connected with the extruder through a heated flexible pressure
tube, and laid down.
[0015] DE 30 47 727 C2 describes a method for producing thin
protective films by spraying liquefied thermoplastic material onto
a substrate. The method described herein is supposed to enable the
use of conventional hot spraying devices, in which injection
material is molten and thus liquefied, which can then be applied
immediately to the surface to be protected. It is further described
that the tendency of these materials to form beads upon impinging
on the surface has until now prevented the formation of a
sufficiently homogeneous film, but according to this description,
this problem is supposed to be overcome in the simplest way by a
simultaneous or subsequent sintering process. Accordingly, for the
sintering of the thermoplastic material, it has been found
advantageous if the sintering is effected by heating the sprayed-on
thermoplastic material in order to arrive at a uniform, smooth and
pore-free application. The heat required for sintering can be
supplied to the thermoplastic material externally by radiant heat,
warm air supply or the like. It may be reasonable to spray the
thermoplastic material onto a previously heated surface, so that
the sintering process occurs simultaneously with the spraying, and
thus a time-optimized course of the process is obtained. However,
the sintering process effected after the material's impinging on
the surface is very complicated and again puts the substrate
material under a thermal load.
[0016] DT 16 46 051 B2 describes a method for applying polymeric
coatings to solid surfaces by spraying on a molten thermoplastic
polymer. Thereafter, melting of the polymer and supplying the melt
in a pressurized gas stream by relief embossing are performed, and
the sprayed gas/polymer jet is subjected to heat jet treatment on
its way to the surface to be coated. It is described that the
thermoplastic polymer of any grain size is converted to the molten
state in extruders or piston cylinder means, and sprayed onto the
surface to be coated, which is previously heated, by means of
pressurized gas using a compressed air injection nozzle in the form
of a gas/polymer jet heated by a heat jet stream.
[0017] DE 32 25 844 A1 describes a method and device for the
application of layers of thermoplastic materials or hot-melt
adhesives. A method for the application of layers of thermoplastic
materials or hot-melt adhesives is described in which the plastic
or hot-melt adhesive employed is molten, then atomized and sprayed.
Preferably, the temperature of the molten plastic or hot-melt
adhesive is kept constant up to the moment of spraying. The device
for performing the method includes a heatable melting means for a
plastic or hot-melt adhesive, a heatable spraying means having a
nozzle, a heatable device for supplying the molten material into
the spraying device, a temperature measuring and temperature
closed-loop control system, as well as closed-loop control systems
for the supply and discharge of a molten material and the heated
spraying gas, if any. By this method, two- or three-dimensional
objects of any kind and shape can be provided with an arbitrarily
thick, uniform or patterned, layer from the outside and/or
inside.
[0018] DE 42 31 074 A1 describes the use of plastic powders as a
filler in sprayable coating compositions, paints and sealing
compositions. It describes the use of powders of a density range of
from 0.1 to 2.0 g/cm.sup.3 having an average grain size of at most
0.2 mm, obtained by mechanical comminution of solid plastic
material that may contain mineral fillers, as fillers, optionally
in addition to further fillers, in sprayable paints, coating and
sealing compositions based on one- or two-component polyurethane
binders.
[0019] DE 101 61 600 A1 describes a method for spraying on plastic
layers. It describes a method and device for applying a
filler-containing plastic layer to a shaped surface, wherein a
mixture containing a mixture of binders, a solids conveyor and a
filler is sprayed onto the shaped surface by first producing a free
jet for spray application from a mixture containing a mixture of
binders and the solids conveyor, followed by metering the filler
into the free jet to the incompletely polymerized mixture of
binders. The method is suitable, in particular, for the spray
application of heavy layers as employed in conventional mass-spring
systems.
[0020] DE 10 2005 058 292 A1 describes a method and device for
producing coated formed parts. Provided are a method and a device
for producing formed parts containing a layer of polyurethane in
shot operation, in which the reactive components are mixed by means
of a cylindrical mixing chamber, and the reaction mixture produced
subsequently flows through a flow channel and is sprayed onto the
surfaces of a substrate, where it cures, followed by cleaning the
flow channel by a gas stream.
[0021] Therefore, it is the object of the present invention to
provide a process by which very different types of
thermoplastically processable materials can be applied to different
kinds of substrate surfaces in the form of a film in a desirable
and defined way.
SUMMARY OF THE INVENTION
[0022] According to the invention, the above object is achieved by
a method for spray-coating substrate surfaces, in which [0023] b(a)
a thermoplastically processable material is molten and thus
liquefied in an extruder in a first step; [0024] (b) the molten
material is pressurized by means of a carrier gas or vapor; [0025]
(c) a mixture formed from said molten material and said carrier gas
or vapor is pressed through one or more nozzles, optionally
supplying a spraying gas having a temperature at least as high as
the melt temperature to the spraying jet in the region of the
discharge opening of the nozzle; and [0026] (d) the obtained spray
jet with the molten material is directed onto the substrate
surface, wherein the material impinges in drops in a flowable state
onto the substrate surface, forms a continuous coating on the
substrate surface, and subsequently solidifies.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0027] According to the invention, a method for spray-coating
substrate surfaces, comprises the following steps : [0028] (a)
melting and thus liquefying a thermoplastically processable
material in an extruder in a first step; [0029] (b) pressurizing by
means of a carrier gas or vapor the molten material; [0030] (c)
spraying a mixture formed from said molten material and said
carrier gas or vapor by pressurizing said mixture through one or
more nozzles, optionally supplying a spraying gas having a
temperature at least as high as the melt temperature to the
spraying jet in the region of the discharge opening of the nozzle;
and [0031] (d) directing the obtained spray of mixture onto the
substrate surface, wherein the material impinges in drops in a
flowable state onto the substrate surface, thereby forming a
continuous coating on the substrate surface, which subsequently
solidifies.
[0032] The core of the invention is essentially the fact that a
thermoplastically processable material is molten alone or as a
compound in a mixture with other thermoplastically processable
materials with or without fillers in an extruder, pressurized with
an inorganic carrier gas or vapor under a defined pressure, pressed
as a mixture through one or more orifice nozzles, released to
atmospheric pressure, and cooled down only on the substrate
surface.
[0033] In a specific embodiment, a compound is directly mixed in a
twin-screw extruder. In another embodiment, this twin-screw
extruder is followed by, for example, a single-screw extruder or a
melt pump.
[0034] Virtually all thermoplastically processable materials can be
employed as materials for spraying, irrespective of whether they
are homopolymers or compounds, unfilled or filled with non-melting
materials. Particularly preferred within the meaning of the present
invention are thermoplastically processable materials such as
homopolymers, co- and terpolymers as well as thermoplastically
processable elastomers, especially selected from
acrylonitrile-butadiene-styrene (ABS), polyamide (PA), polylactate
(PLA), polymethyl methacrylate (PMMA), polycarbonate (PC),
polyethylene terephthalate (PET), polyethylene (PE), polypropylene
(PP), polystyrene (PS), polyether ether ketone (PEEK) and polyvinyl
chloride (PVC) including copolymers and compounds thereof, which
may optionally contain further components, especially fillers. In a
specific embodiment, high-performance materials, such as PEEK, may
also be sprayed with a high proportion of gas and an associated
viscosity reduction. The amount of the fillers can be varied
widely, wherein the amount of the fillers preferably should not
exceed 80% by weight, based on the material, because otherwise the
cohesion of the coating cannot be ensured.
[0035] The fillers themselves may be inorganic in nature, or
polymers that do not melt at the processing temperature, such as
rubber, wherein the fillers do not have a preferred direction.
Further, inorganic short fibers, polymeric fibers having a melting
temperature higher than the processing temperature of the material
or the compound as well as natural fibers may be employed as
fillers.
[0036] A material structure that differs from layer to layer can be
produced by changing the mixture, the thermoplastically processable
material and/or the filler itself and the ratio of
thermoplastically processable material to filler in the course of
the spraying process.
[0037] Inert, especially inorganic, gases or mixture of gases as
well as vapors suggest themselves as the carrier gas. Particularly
preferred according to the invention is the use of, for example,
nitrogen, carbon dioxide, air or water, which is gaseous at this
temperature.
[0038] The carrier gas or vapor is preferably employed at a weight
ratio of thermoplastically processable material to carrier gas or
vapor within a range of from 100:0.1 weight parts to 100:30 weight
parts, especially from 100:0.3 to 100:15 weight parts. Preferably,
a spraying jet with a pressure of from 10 to 500 bar, especially
from 20 to 400 bar, is sprayed.
[0039] With increasing pressure, the droplet size is reduced; the
application of material becomes more homogeneous thereby. However,
with increasing pressure, the material cools down more quickly upon
expanding and relaxing. Depending on the material, this has the
result that no bonding with the substrate surface is achieved any
more. In this case, a pressurized heated gas (spray gas),
preferably air, must be supplied, which provides for additional
atomizing in a favorable case.
[0040] The nozzles are provided, for example, on a flexible
pressure tube and can be moved over the substrate surface by means
of robots to enable a complete application of material. The
nozzle(s) itself (themselves) is (are) designed, for example, as
(an) orifice nozzle(s) with 1 to 50 orifices, preferably 5 to 20
orifices, with a diameter of from 0.1 mm to 10 mm, preferably from
0.5 mm to 2 mm, or orifices having an equivalent cross-sectional
area of defined orifice geometry of the mentioned orifice
diameters. Hot air (spray gas) can be introduced for additional
heating.
[0041] Slotted nozzles having dimensions of 0.1-3.0.times.3-30 mm,
preferably 0.5-2.0.times.5-10 mm, may also be employed; in this
case too, several slotted nozzles may be provided in the spray
head.
[0042] In addition to the above mentioned substances and elements
that are gaseous at room temperature (normal pressure) or at the
processing temperature, the term "carrier gas" within the meaning
of the present invention also includes those substances that form
gaseous substances by a chemical or thermal reaction, or are
converted to the gaseous state. Hot air is particularly preferred
in this respect.
[0043] The chemical composition of the spray gas, which is
preferably guided around the discharge opening of the thermoplast
in the form of an annular nozzle, can be the same as or different
from the carrier gas. Hot air is particularly preferred as a spray
gas, which causes further expansion of the carrier gas in the
thermoplast and heating of the particle surface.
[0044] In the following, the invention is illustrated by means of
two Examples.
EXAMPLES
Example 1
[0045] Commercially available KraussMaffei Berstorff extruders ZE40
Ax29D and KE90x3OD in series were employed, each equipped with
specifically designed screws. The die was a single casing head with
24 orifice nozzles of 1.1 mm orifice diameter each, arranged in two
rows.
[0046] A compound of 75% by weight inorganic filler (barite) and
25% by weight of a commercially available plastic mixture of
PE/EVA, white oil, flow additive and temperature stabilizer in the
form of granules was employed as the thermoplastically processable
material.
[0047] The output capacity was 90 kg/h, and the gas quantity
(carrier gas) was 1.1 kg/h CO.sub.2. A commercially available
pressed mixed fiber nonwoven served as the substrate surface.
[0048] With these settings, a good spray performance was achieved,
and a flexible plastic layer was produced on the textile
surface.
Example 2
[0049] In principle, essentially the same setting as in Example 1
was used in a second application in this Example. The nozzle has
been changed. Here, a circular jet nozzle of the BETE company was
used, in which heated air as a spray gas in an outer ring around
the discharge nozzle heated the mixture of carrier gas and
compound. The amount of carrier gas was reduced to 400 g/h. In the
material employed, the filler was reduced to 25% by weight, and the
amount of compound was increased accordingly.
[0050] The output capacity was 60 kg/h. The amount of air employed
(spray gas) was 30 standard cubic meters per hour, heated at
300.degree. C. The spraying result was improved over that of
Example 1.
* * * * *