Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Title: Method and Apparatus for Surface Treatment of Extmded PVC
Inventors: Eugene Iacobelli
BACKGROUND OF THE INVENlION
S Field of the invention
This invention relates to surface treatment for extruded PVC and in
particular a method and apparatus for painting extruded PVC to produce a composite
surface structure.
Description of the Prior Art
Extruded polyvinyl chloride (PVC) has a myriad of uses. For instance
extruded PVC is used for vertical blinds, horizontal blinds, venetian blinds, picture
frames, shutters and construction materials such as eave troughs, moldings, baseboards,
cornices, siding, door casings and window casings. For most of these applications the
colour and aesthetics of the extruded PVC is important to the end user.
In the past, to change the appearance of a specific PVC product, colour
was added to the PVC prio~r to it being extmded and formed into the ~mished product.
Howeve~, for many applications only certain colours are used sis~ce dark coloured PVC
tends to deform in the hot sun.
A more recent development, particularly for PVC used as blinds, has been
to apply a patterned cellophane-like fflm to the PVC to produce different visual eff~cts on
the PVC. In thi~ proGess the PVC is typically a light colour and the film is applied to
only one side of the item. Therefore the uncoated side of the PVC produc~ can be
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positioned toward the sunl;ght and the item will tend not to deform in the sunlight.
Applying a film to the PVC however typically adds at least 50% to the pr;ce of the item
and therefore is relatively costly. Also, air bubbles may be trapped between the film and
the PVC and be visible.
Another recent development in PVC blinds is to manually spray paint the
blinds with a variety of colours after the blinds have been manufactured. Typically, as
discussed above, only one side of the blind is painted so that the light coloured side of
the blind can face toward the sun and therefore the blind will tend not to deform. Spray
painting the blinds provides a textured surface and colour combinations only limited by
the imagination. In order to make the paint adhere to the PVC a primer must first be
applied. Further, often when paint is applied by hand there will be a certain amount of
overspray, that is, paint that gets on the back of the blind. This, of course, is
undesirable and is difficult to eliminate without further apparatus and expense. Further
because the paint is applied after the blind is finished, the paint tends to chip. The
painted vertical blinds are visually appealing, however they are costly due to the manual
labour required to perform the painting step.
Until the present invention there has not been a method of producing
painted extruded PVC where the painting step forms part of the fabrication procedure, the
paint and the PYC form a composite stMcture and the paint forms an integral part vf the
extruded PVC. Further until the present invention there has not been an automated
method of producing extruded PVC that have the visual appeal of painted PVC.
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SUMMARY OF THE INVENTION
The present discloses a method and apparatus for producing painted
extruded PVC wherein the paint and the PVC form a composite surface structure. The
method comprises the steps of extruding the PVC; then spraying the extrucled PVC with
S paint; then drying the painted extruded PVC; and finally cutting the dried painted
extruded PVC into predetermined lengths. The apparatus comprises a PVC extruding
device; a paint source; a paint sprayer connected to the paint source for spraying paint
onto the extruded PVC; a drier for drying the painted extruded PVC; and a cutting device
~or cutting dried painted extruded P51C.
Further features of the invention will be described or will become apparent
in the course of the following detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described by way of example only, with
15 reference to the accompanying drawings, in which:
Fig. 1 is a schematic view of the process of treating extruded PVC with
paint as part of the fabrication procedure forming the present invention;
Fig 2 is a diagrammatic view of the apparaéus of the present invention;
Fig. 3 is an elevational view of the paint station taken along line 3-3 in
20 Fig. 2;
Fig. 4 is an enlarged view of the paint gun;
Fig. S is an enlarged view of the paint gun similar to Fig. 4 with the paint
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sprayer adjusted to apply a greater amount of paint than in Fig. 4; and
Fig. 6 is a top view of a portion of a painted PVC blind painted inaccordance with the process of the present invention.
S DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to the drawings and in particular to Fig. 1, the polyvinyl chloride
(PVC) extruding system of the present invention is generally indicated by reference
numeral lû. The main components of the system include a PVC extruding device 12, a
painting station 14, a drying zone 16, and a cutting device 18.
Extruding device 12 is a conventional device that is used to extrude PVC
in predetermined shapes.
Once the PVC is extruded paint is applied to it. In the preferred
embosliment the paint is applied by a pressurized paint gun described in detail later.
Pre~erably, the paint gun is one in which the amount of paint can be varied and the
amoImt of pressure at which the paint is sprayed onto the extruded PVC can be varied.
Accordingly, the parameters of the paint gun can be varied to produced a number of
different visual and textural e~fects. Alternatively, a paint gun may be used in which the
amount of paint sprayed on the extruded PVC and the pressure is fixed to produce a
predetermined visual and textural effect.
Painting station 14 is between extrusion device 12 and drying zone 16 so
that the paint bonds with the PVC before the PVC sets and the paint dries. Thus the
paint and the PVC ~orm a composite sur~ace structure and the paint becomes an integral
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part of the PVC product.
Setting and drying zone 16 is similar to that which is found in conventional
PVC extrusion systems. In this zone the PVC is set and the paint is dried. The only
variation from a conventional PVC system may be to increase the length or temperature
5 of the drying zone to ensure that the painted PVC is sufficiently dry and set.
Similarly, cutting device 18 is similar to that which is found in
conventional PVC extrusion systems.
The apparatus will now be described in detail with reference to Figs. 2
through 5.
An extrusion device 20 extrudes PVC 19 in a predetermined shape. The
extruded PVC is transported from station to station on a conveyor like system 21 which
keeps the extruded PVC constantly moving through the system.
Painting station 14, shown in F;g. 2 includes a paint source 22, a paint gun
24 directed towards the extruded PVC 19, a paint shield 26 and a pressurized air line 28.
Paint source 22 may be a bucket of paint or any other source of paint that
is available. Paint source 22 is attachecl to pressurized air line 28 to force the paint into
paint glm 24. An adjustable valve 30 is attached between pressurized air line 28 and
paint source 22 so ~hat the amount of air pressure applied to the paint may be varied,
thereby varying the amount of paint which is forced into paint gun 24. If the pressure on
20 paint source 22 is increased the amount of paint forced into paint gun 24 is increased and
the amount of paint spayed onto extruded PVC 19 is increased. Typically this will also
increase the texture on the surface of the extruded PVC.
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Preferably, for a multicolored look, the paint that is used is paint which
maintains discrete colours and will not mix into a homogeneous colour. Alternatively, a
single colour of paint may be used which produces a textured look, generally this will
give a two coloured effect since the colour of the extruded PVC will be seen through the
5 applied colour.
Spray gun 24, shown in Figs 2 through 5, is attached to pressurized air
line 28 through adjustable valves 32 and 34 so that the air pressure into the gun may be
varied. Valve 32 controls the air pressure into the glm and is set at a predetermined
level. Typically this level is determined by the paint gun manufacturer and is set so that
10 the gun functions properly. Valve 34 controls the air pressure at which the paint is
sprayed onto the extruded PVC 19 as shown in Figs. 4 and 5. By varying the pressure at
which the paint is sprayed onto the extruded PVC the thickness of the paint lines is
varied thus changing the ove~all look and texture of the painted PVC.
The paint shield 26 is positioned relative to the paint gun 24 as shown in
15 Figs. 2 and 3. The paint shield 26 protects the work environment from paint that misses
the extruded PVC 19.
Two air driers 36 blow cool air onto the extruded and painted PVC 19 to
set the PVC and dry the paint.
A cutter 38 cuts the cooled painted extruded PVC into predetermined
20 lengths.
Fig. 6 shows a poItion of a cooled painted extruded PVC 19. As can be
seen there are a multiplicity of lines and dots of paint. As discussed, the paint may be
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multicolored or a single colour as desired by the end user.
It will be appreciated by those skilled in the art that the painted PVC blindsof the present invention are superior to the manually painted blinds because the apparatus
may be set at specific levels so that the amount of paint and the thickness of the paint is
S consistent. Further, since the paint is applied before the PVC is fully set the paint and
the PVC form a composite surface structure and the paint forms an integral bond with the
PVC. Therefore the paint will he less prone to chip or peel off. Further, no primer is
required. Therefore the method and apparatus of the present invention provides a cost
effective method and apparatus for producing visually appealing painted PVC.
It will be appreciated that the above description related to one ernbodiment
by way of example only. Many variations on the invention will be obvious to those
skilled in the art and such obvious variations are within the scope of the invention as
described herein whether or not expressly described.
For example a paint gun having a cavity for paint could be used.
15 Alternatively, a paint gun having a fixed nozzle pressure could be used.
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