U.S. patent application number 10/688126 was filed with the patent office on 2004-06-10 for molded articles having a surface bearing a lenticular image.
Invention is credited to Goggins, Timothy P..
Application Number | 20040108606 10/688126 |
Document ID | / |
Family ID | 26905843 |
Filed Date | 2004-06-10 |
United States Patent
Application |
20040108606 |
Kind Code |
A1 |
Goggins, Timothy P. |
June 10, 2004 |
Molded articles having a surface bearing a lenticular image
Abstract
Disclosed herein is a molded article bearing a lenticular image
on its surface that is prepared by a method comprising the steps
of: A. providing a mold in which to form the molded article; B.
inserting a lenticular image into the mold; C. introducing a molten
plastic into the mold to form the molded article with the
lenticular image attached to a surface of the molded article; and
D. removing the molded article with the attached lenticular image
from the mold.
Inventors: |
Goggins, Timothy P.;
(Nashotah, WI) |
Correspondence
Address: |
WHYTE HIRSCHBOECK DUDEK S C
555 EAST WELLS STREET
SUITE 1900
MILWAUKEE
WI
53202
US
|
Family ID: |
26905843 |
Appl. No.: |
10/688126 |
Filed: |
October 17, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10688126 |
Oct 17, 2003 |
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09718695 |
Nov 22, 2000 |
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6635196 |
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60211112 |
Jun 12, 2000 |
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Current U.S.
Class: |
264/1.1 |
Current CPC
Class: |
B29C 45/14811 20130101;
B29K 2995/002 20130101; B29C 45/14688 20130101; B29C 49/00
20130101; B29K 2715/006 20130101; B29L 2031/3431 20130101 |
Class at
Publication: |
264/001.1 |
International
Class: |
B29D 011/00 |
Claims
What is claimed is:
1. A method for making a molded article, the method comprising the
steps of: A. providing a mold in which to form the molded article;
B. inserting a lenticular image into the mold; C. introducing a
molten plastic into the mold to form the molded article with the
lenticular lens attached to a surface of the molded article; and D.
removing the molded article with the attached lenticular image from
the mold.
2 The method of claim 1 further comprising the step of delivering a
plurality of lenticular images to an area near the mold and
inserting at least one of the plurality of lenticular images into
the mold using a robotic arm.
3 The method of claim 1 in which the mold has an open cavity
defined by a surface and the lenticular image, the lenticular image
comprising a lens and an interlaced image, is oriented within the
mold cavity such that the lens is positioned along at least part of
the cavity surface.
4. The method of claim 1 in which the molten plastic is introduced
at a temperature and pressure so as to result in little, if any, of
at least one of distortion to the lenticular lens and degradation
to the underlying image.
5. The method of claim 1 wherein the molten plastic is introduced
in a shot size quantity that packs the mold so as to result in
little, if any, of at least one of distortion to the lenticular
lens and degradation to the underlying image.
6. The method of claim 1 in which the lenticular image further
includes at least one of a substrate, an adhesive, and a
coating.
7. The method of claim 6 in which the substrate comprises one of:
paper, synthetic paper, plastic, metal, glass, or wood.
8. A molded article having a surface comprising a lenticular image
made by the method of claim 1.
9. The molded article of claim 8 in which the molded article is
further defined to be one of a flash molded, a positive pressure
molded, a transfer resin molded, a blow molded, or an injection
molded article.
10. A molded article comprising a molten plastic that has cooled
and hardened, the article bearing a lenticular image that is joined
with the plastic in an integral fashion.
11. A method for making a molded article, the method comprising the
steps of: A providing a mold in which to form the molded article,
at least one part of one surface of the mold shaped to impart a
lenticular lens configuration to a portion of the at least one
surface of the molded article; B. inserting an interlaced image
into the mold, the image positioned over the part of the mold
shaped to impart a lenticular lens configuration to the molded
article; C. introducing at least one type of molten plastic into
the mold to form the molded article and a lenticular lens
configuration comprising lenticules on at least part of the at
least one surface of the molded article, the image positioned in a
manner so as to correspond to the lenticules of the lens forming a
lenticular image; and D. removing the molded article with the
attached lenticular image from the mold.
12. An in-mold method for making an injection molded article, the
method comprising the steps of: A. providing a mold in which to
form the molded article, the mold having a cavity with a surface;
B. inserting a lenticular image into the mold so that the
lenticular image is placed along the cavity surface; C. introducing
a molten plastic into the mold to form the molded article with the
lenticular image attached to a surface of the molded article; and
D. removing the molded article with the attached lenticular image
from the mold.
13. The method of claim 11 wherein the lenticular image is held in
place along the cavity surface.
14. The method of claim 11 further comprising the step of cooling
the molded article, the article comprising the attached lenticular
image, so as to create a finished molded article.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates generally to molded articles.
In one aspect, the invention comprises molded articles bearing a
surface image while in another aspect, the invention relates to
molded articles bearing a lenticular image. In yet another aspect,
the invention pertains to a method of making molded articles
bearing an image, and more particularly, a lenticular image.
[0002] Molded articles and their methods of manufacture are well
known in the art. Typically, these articles are molded from any one
of a number of common plastics, e.g., ABS, acrylic, polystyrene,
polyethylene, polypropylene, PET, nylon, polycarbonate, and the
like, and these articles are molded into any one of a host of
different sizes and shapes, e.g., telephone, compact disc and
cosmetic cases, cups, bottles, promotional items, automobile and
appliance parts, etc. These products are molded or shaped by any
one of a number of different processes, e.g., injection molding,
resin transfer molding, blow molding, pressure molding, and the
like. Such parts can be complex, that is, comprising more than one
injection molded part. For example, a cosmetic case can include an
opaque portion and a separately or even simultaneously molded clear
portion.
[0003] The aesthetic quality of a molded plastic part is, of
course, dependent in large part upon its ultimate use. For those
products that are used in applications in which their use is not
visible to an end user, e.g., fasteners, plugs, etc., the
aesthetics of the product are of little, if any, importance. For
those products that are used in applications in which their use is
visible to an end user, or in which their appearance is important
to their sale, e.g., promotional items, automobile and appliance
facie, cups, bottles, bottle caps/enclosures, snowboards or wake
boards, skis (e.g., water, snow), cameras, computer cases (e.g.,
laptop cases), cell phone (or other electronic) cases, cosmetic
cases, collectibles, signs, magnets, coasters, display posters,
menu boards, postcards, business cards, and packaging on boxes, the
aesthetics of the product are important.
[0004] One way to improve the look of a product is to incorporate
into it bright color schemes and fancy or even glitzy decor so as
to attract and keep a viewer's attention. The application of a
lenticular image is one form of such a dcor. As here used, a
"lenticular image" means a segmented image comprising two or more
component images, the segments interlaced in any conventional
manner, and mapped (i.e., aligned) to a lenticular lens. In
general, lenticular imaging is known, commercially available and
described in U.S. Pat. Nos. 5,113,213; 5,266,995; 5,488,451;
5,617,178; 5,847,808; 5,896,230 and 5,967,032 (all of which are
incorporated herein by reference), and U.S. application Ser. No.
09/536,246.
[0005] The incorporation of a decorative surface feature into a
molded product is known, e.g., U.S. Pat. Nos. 5,514,427; 5,985,198;
5,972,279; 5,968,444; 5,951,939; 4,906,315; 4,668,558; 4,582,885;
4,576,850 and Re. 36,457 (all of which are incorporated herein by
reference).
[0006] In general, molded parts are used in a variety of
applications and lenticular images provide an attractive and
eye-catching way to improve the overall aesthetic appeal of an
object to the viewer. Current technology provides for injection
molding of colored plastics and plastics which can incorporate such
decorative features as, for instance, a "sparkle."
[0007] A method for manufacturing a molded article having a
decorative surface layer comprising a lenticular image is of
interest to the injection molding industry as well as consumers of
molded products in general in that it can provide a product that is
simply more beautiful or attractive. On another level, the product
can be used to communicate a message (inanimate though it may be)
via the decorative lenticular image. A method that can promote the
integrity of the lenticular image and the lenticular image's
adhesion to the molded article while also protecting the optical
properties achieved by the lenticular lens surface is
desirable.
SUMMARY
[0008] According to this invention, a molded article bearing a
lenticular image is prepared by an in-mold method comprising the
steps of:
[0009] A. providing a mold in which to form a molded article;
[0010] B. inserting a lenticular image into the mold;
[0011] C. introducing a molten plastic into the mold to form the
molded article with the lenticular image attached to a surface of
the molded article; and
[0012] D. removing the molded article with the attached lenticular
image from the mold.
[0013] In one embodiment of this invention, the molded article is
formed by an in-mold method of injection molding in which the
lenticular image is placed on the surface of one or both halves of
the mold and held in place with a vacuum assist, the molten plastic
injected into the mold to create the molded article with the
lenticular image attached to the surface of the article, and the
mold subsequently opened and the finished article removed.
[0014] In another embodiment of this invention, the lenticular
image bears a coating over the segmented, interlaced and mapped
image that protects the integrity of the image from distortion
and/or degradation that would otherwise result from the heat and
pressure of the molten plastic during the molding process. In other
embodiments of this invention, the temperature and pressure of the
molten plastic is selected and/or controlled, and/or the gate
placement is selected, such that the integrity of the lenticular
image remains undistorted without the need for a protective
coating.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 is a flow chart illustrating one method of making a
molded article with a surface bearing a lenticular image.
[0016] FIGS. 2a-d are cross-sectional views of typical lenticular
images.
[0017] FIG. 3a shows a robotic arm picking or grasping a typical
lenticular image from a stack prior to placing the lenticular image
into a typical mold, the mold shown in an open position.
[0018] FIG. 3b shows a robotic arm placing a exemplary lenticular
image into position within a mold, the mold in an open position,
prior to the introduction of molten plastic into the mold.
[0019] FIG. 3c shows a lenticular image placed within a mold, the
mold having a moveable portion and a stationary portion, the
moveable portion of the mold moved so that the mold is in a closed
position, and molten plastic having been introduced into the
mold.
[0020] FIG. 3d shows a robotic arm removing a molded article from a
mold that is in an open position, the molded article comprising a
lenticular image that has been joined with a molten plastic
material that has hardened.
[0021] FIG. 4 shows a typical lenticular image joined to an
optional layer, the optional layer comprising a protective coating
or substrate material.
[0022] FIG. 5 shows a typical lenticular image having a coating
layer and joined to an optional layer comprising, for instance, a
substrate material.
[0023] FIG. 6 shows an enlarged version of the lenticular image
having an optional layer comprising a protective coating or
substrate material disposed within a mold, the view taken along
line 6-6 of FIG. 3c. A molten plastic material is shown being
introduced using arrows via a typical hook gate arrangement.
[0024] FIG. 7 shows a lenticular image having an optional layer
comprising a protective coating or substrate material disposed
within a mold. A molten plastic material is shown being introduced
using arrows via a typical sub gate arrangement.
[0025] FIG. 8 shows a lenticular image having an optional layer
comprising a protective coating or substrate material disposed
within a mold. A molten plastic material is shown being introduced
using arrows via a typical edge gate arrangement.
[0026] FIG. 9 shows an enlarged cross-sectional view of a molded
article.
[0027] FIG. 10 shows one embodiment of a molded article bearing a
lenticular image.
[0028] FIG. 11 shows a cross-sectional view of a mold for making
the molded article bearing a lenticular image of FIG. 10. A molten
plastic material is shown being introduced into the mold using
arrows and via a typical gate arrangement. Inside the mold is a
lenticular image
[0029] FIG. 12 shows a cross-sectional view of the mold taken along
line 12-12 of FIG. 11.
[0030] FIG. 13 shows a cross-sectional view of the mold taken along
line 13-13 of FIG. 11.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0031] The preparation of lenticular images is well known in the
art. The lenticular image is, by definition, a composite of two or
more component images that are preferably of photographic quality.
The component images are selected based upon the desired features
of the lenticular or final image. The component images are then
arranged, segmented, interlaced and mapped to correspond with the
lenticular lens in any convenient manner, e.g., such as those
taught in U.S. Pat. Nos. 5,488,451; 5,617,178; 5,847,808 and
5,896,230 all of which are incorporated herein by reference.
"Correspondence" between an interlaced image and a lenticular lens
is achieved when the interlaced image can be viewed properly
through the lenticular lens and the viewer perceives the desired
visual effect (e.g., motion and/or depth). The image can be printed
directly to the flat back surface of a lenticular lens, e.g., such
as that taught in U.S. Pat. No. 5,457,515 (which is incorporated
herein by reference), or to a substrate (e.g. paper, synthetic
paper, plastic, glass, metal or wood) that can be subsequently
joined to the lens.
[0032] Lenticular lenses typically take the form of a sheet or web.
The sheet includes an array of identical curved surfaces that are
formed (e.g., embossed, cast, or extruded) on the front surface of
a plastic sheet, and the back surface of the lens is typically
flat. Each individual lens or lenticule is a section of a long
cylinder that typically extends over the full length of the
underlying image. The image can be printed directly to the flat
back surface of the lens, or alternatively, the lens can be
laminated to the image. The lenticular lens is generally selected
to accommodate both the image and the distance from which the image
will ordinarily be viewed.
[0033] Other factors to consider when selecting a lenticular lens
include: the lens sheet thickness, its flexibility and, of course,
the cost of the lens material. For a large application, such as a
snowboard surface, a thick, coarser lenticular lens is usually
preferred. For smaller applications, for example, a cup, key chain,
necklace charm, or cosmetic or compact disc case, a thin, finer
lenticular lens may be preferred. Coarse lenticular lenses have
fewer lenticules per linear inch than fine lenticular lenses. The
front (i.e., the surface having the identically curved surfaces)
can include a protective layer. Alternatively, a "slip sheet" can
be used. In either case, the layer or slip sheet can be removed
once the lens is shipped from a manufacturer (i.e., an extruder) to
an end user.
[0034] Shown in FIGS. 2a-d (and similarly, in FIGS. 4 and 5) are
cross-sectional views of a few of the various embodiments of a
typical lenticular image 10a for use in the present invention. As
shown in FIG. 2a, below and adjacent to flat backside 12a of
lenticular lens 12, and typically printed upon it, is an image 14
(preferably comprising the interlaced image described above). An
optional coating (also called "floodcoating", or "spotcoating") 16,
such as a vinyl plastic or opaque white ink can also be applied to
enhance, or provide contrast for, the image. This coating can also
be used to provide a special effect, for example, a
glow-in-the-dark effect. Such an optional coating is described in
U.S. Pat. No. 5,896,230, incorporated by reference above.
[0035] A coating, such as coating 16, can also serve to protect the
lenticular image, (i.e., the lenticular lens itself, the underlying
interlaced image, or both). By way of example, the coating can
effectively reduce distortion of the image and/or other degradation
(e.g., melting of the lenticular lens) that may result from
exposure to excessive pressure and/or heat that may be present
during a molding process. One such coating, a "silk screen"
coating, is disclosed below with reference to a specific embodiment
of the invention.
[0036] FIG. 2b shows another embodiment of the present invention in
which coating 16 (e.g., a clear coating) is applied below and
adjacent to flat backside 12a of lenticular lens 12 and image 14 is
printed on the coating. Additionally, an optional layer 18 is
shown, the layer comprising a substrate or other coating. As
described above, this layer can be included to protect the image,
for instance, from heat, pressure, and/or turbulence of molten
plastic flow.
[0037] FIGS. 2c-d illustrate two ways in which an adhesive can be
applied to the lenticular image 10a. In FIG. 2c, adhesive 20 is
applied below and adjacent flat backside 12a of the lenticular lens
12. In this example, image 14 is first printed to substrate 22 and
affixed to the lens using the adhesive. As a practical matter, the
substrate can be made of wood, metal, glass, or plastic, and the
adhesive can be any adhesive compatible with the substrate, coating
and/or ink of the segmented and interlaced image. Finally, in FIG.
2d, image 14 is printed to flat back surface 12a of lens 12. The
image is affixed using adhesive 20 to layer 18 (again, a substrate
or coating).
[0038] FIG. 4 illustrates another cross-sectional view, similar to
that of FIGS. 2a-d, of a typical lenticular image 10a comprising a
lenticular lens 12, an image layer 14 and having an optional layer
18 comprising a protective layer or substrate. FIG. 5 shows a
typical lenticular image 10a having lens layer 12, an image layer
14, with a protective coating layer 16, and an optional layer 18
comprising a coating or substrate material.
[0039] The following description of the method of this invention is
in the context of an injection molding process. However, the method
of this invention is also applicable to other molding processes,
such as: flash molding, positive pressure molding, transfer resin
molding, and blow molding and others.
[0040] Injection molding provides an economical and rapid way to
produce high quality precision parts (for example, containers such
as a cup or computer case, or for a laptop computer) from a wide
variety of plastic materials. Representative of these materials
are: polyvinyl chloride, polycarbonate, polystyrene, polyethylene,
polypropylene, ABS rubbers, polyethylene terephthalate glycol,
acrylic, nylon and RIM urethanes. Polyolefins, homopolymers and
co-polymers (ionomers, etc.) are also inexpensive thermoplastic
resins that have excellent molding properties and are mentioned
here as potentially suitable for use. Additionally, certain
thermoplastic elastomers, such as the TPO's (thermoplastic olefin)
elastomers, may be employed as desired. Generally, this invention
can be viewed as applicable to a variety of molten, solidifyable
materials, which, besides plastic, might include materials such as
glass. For purposes of the present invention, and as a practical
matter, conventional molding equipment may be used and, although
not shown, is known to those of skill in the molding art.
[0041] In general, plastic granules or pellets are heated until
melted, (the melting temperature a function of the plastic, among
other things, but typically between about 200 to 500 F). Once
melted, the plastic is forced under high pressure (e.g. 10,000
pounds per square inch or more) into a rigid mold press. The mold
press is often made of a metal such as aluminum or steel. Once the
mold is filled, the molten plastic cools and resolidifies,
producing a part with the desired shape and appropriate
dimensions.
[0042] Referring to FIGS. 3a-d and FIGS. 6-8, typically a mold 31
comprises a stationary portion 32 and a movable portion 34, the
moveable portion capable of being moved from an open position
(shown in FIGS. 3a-b) to a closed position (FIGS. 3c-d) having a
cavity with a surface 35. At least one of the halves can be
equipped with one or more runners or channels for delivering a
molten plastic to the cavity via at least one injection gate (FIGS.
6-8, numbers 38a-c, described below). A vacuum assist (or some
other means, for instance, static electricity, gravity or tension
of the material itself) can be used to hold a part in place, (one
such part being a lenticular image of the kind described herein).
The injection gates are preferably sized to accommodate the part
that is to be manufactured. Such aspects of the present invention
(i.e., the size and placement of various items, for instance, the
runners and gates) can be determined by those of skill in the art
of injection molding.
[0043] Referring to FIGS. 6-8, a variety of gate types can be
employed to provide molten plastic to the mold in a fashion that
reduces deterioration or degradation to the lenticular image (such
as, for example, melting of the lenticular lens material, or
distortion to the interlaced image itself). These include, but are
not limited to, hook gates, edge gates and sub gates. "Hook" gates
(for example, a "banana" or "j" hook gate) refer to those gates
that provide for molten plastic to flow into the mold cavity
generally directly behind (or beneath) the lenticular image (e.g.,
a side opposite the lenticular lens). A typical hook gate 38a
arrangement is shown in FIG. 6.
[0044] A typical edge gate 38c arrangement is shown in FIG. 8.
"Edge" gates, as used herein, generally refer to those gates that
can permit the flow of molten plastic along (or at a seam or gap
between) the stationary half and the moveable core.
[0045] FIG. 7 shows a typical sub gate 38b arrangement. In this
application, "sub" gates refer to those gates that provide molten
plastic to be angled away from the image surface (or surface and
protective layer) such that the plastic can be injected off of, for
instance, the moveable core prior to joining molten plastic with
the surface of the lenticular image opposite the lenticular lens.
Thus, sub gates can substantially reduce direct contact (or
impingement) of molten plastic with the side of the lenticular
image bearing the interlaced image.
[0046] As such, sub gates are typically preferred to hook gates and
edge gates since they provide the needed time for the temperature
of molten plastic to decrease prior to contacting the lenticular
image (or other backing surface). This, in turn, reduces the
potential for deleterious effects on the lenticular image (again,
either the lenticular lens itself, the printed interlaced image, or
both) due to excessive temperature. In addition, sub gates provide
a way to inject molten plastic in a manner that can exert a more
controlled and less turbulent flow of molten material along the
back surface of the lenticular image.
[0047] In alternative embodiments of this invention, the mold is
equipped with two or more injection gates, and the placement of the
gates (also called ports) can vary to convenience. In certain
circumstances, the ports are placed distal or oblique to the
lenticular image so as to minimize any distortion or other
deleterious effects (e.g., burning) of the image or the lenticular
lens itself (e.g., melting) that may result from the heat and/or
pressure of the molten plastic.
[0048] Referring to FIGS. 3a-d, in operation, the two halves of the
mold begin in an open position, i.e., extended apart from one
another. In a preferred embodiment of this invention, a plurality
of appropriately sized lenticular images (preferably the images are
die cut or similarly portioned from larger sheets) are delivered to
an area near the mold in a stack 10 (or alternatively, on a tape),
as shown in FIG. 3a. The images can then be removed individually
from the stack (or tape) and placed within the mold through a
pick-and-place motion of a robotic arm 40.
[0049] Referring to FIGS. 3a-c, lenticular image 10a is positioned
within stationary portion 32 (or alternatively, on moveable core
portion 34) and held in place through the action of vacuum assist
(or optionally, static electricity--separately or in addition to
the vacuum assist--can be used to promote positioning of the
lenticular image within the mold). The lenticular image is
preferably oriented within the mold such that the lenticular lens
is positioned between the interlaced image (which is typically
attached to the lens itself as described previously) and the
surface of mold half 32 (or the surface of moveable core 34), which
is preferably polished. Moveable core portion 34 (also preferably
having a polished surface) is then closed (shown in FIG. 3c) upon
stationary portion 32, leaving a cavity or gap between the surface
of the stationary portion and the core portion into which molten
plastic is injected.
[0050] Referring to FIGS. 6-8, the molten solidifyable material,
i.e., the plastic, is injected (via a variety of gate arrangements,
e.g., book, edge, or sub) in a manner as illustrated by the
respective arrows of each Figure. The temperature and pressure are
sufficient to ensure proper formation of the molded part without
distortion of the lenticular image. Of course, the working
temperature and pressure of the molten plastic is a function of a
number of variables, e.g., the composition of the plastic, the
composition and structure of the lenticular image, etc., but as a
practical matter, the temperature and pressure experienced by the
surface of the lenticular image exposed to the plastic (e.g., ink,
protective coating, substrate, etc.) is sufficiently below that at
which the surface deteriorates or otherwise degrades.
[0051] As the molten plastic material flows between stationary mold
32 and moveable core 34, it pushes the lenticular part against the
stationary mold cavity surface. Thus, a pressure is created by the
molten plastic flowing into the mold that exerts a force on the
lenticular lens. The lens surface is pushed up against the
stationary half, holding it in place. Further, the pressure
promotes better adhesion between the molten plastic and the
lenticular part. This action (not shown), coupled with the vacuum
assist (or, for example, static electricity), prevents any
substantial molten plastic material from flowing between the cavity
surface and the decorative surface containing the lenticular lens
material.
[0052] The mold halves are then cooled. Of course, mold
temperatures must be selected such that the molten plastic does not
unacceptably degrade the lenticular image, and in particular, the
optical properties promoted by the curved surface of the lens.
Additionally, the temperature must accommodate the plastic so as to
permit it to set sufficiently such that lenticular image is
permanently affixed to the surface of the injection molded
article.
[0053] Referring to FIG. 3d, once adhesion is achieved and the
plastic set and cooled, mold portions 32 and 34 can be separated.
The vacuum assist can be disengaged, and the molded article bearing
the lenticular image can then be removed using robotic arm 40.
[0054] FIG. 9 shows an enlarged cross-sectional view of a molded
article 50 bearing a lenticular image 10a. The multiple layers
shown in FIGS. 6-9 generally correspond to those layers described
above with reference to FIGS. 2a-d and FIGS. 4-5.
[0055] FIG. 10 illustrates an injection molded product (i.e., a
cup) 60 made in accordance with an embodiment of the present
invention, the product having attached to it (or otherwise bearing)
lenticular image 70 which itself comprises a plurality of
individual elements or images (i.e. fish) 70a, 70b, and 70c, etc.
One such cup has at its top end an open, circular, upper diameter
of about 3.50 inches, and at its bottom end a smaller, circular
diameter of about 2.25 inches, with a frustoconical sidewall
depending between the open top and bottom. The cup has a height of
about 6 inches. Lenticular image 70 can typically be produced as a
lenticular part 10a of the kind described above (e.g., FIGS.
3a-3c). In this case, the part is typically produced and sized as a
flat piece that is shaped to accommodate a curved surface of the
cup (e.g., as a sleeve). The part can be sized and shaped to cover
substantially the entire outer surface of the finished cup, or a
portion thereof (e.g., a "belly band"). The lenticular part can be
positioned along the inner surface of such a cup as well.
[0056] Referring next to FIG. 11, a cross-sectional view of a mold
80 is shown, the mold comprising mold portions 80a and 80b (one of
which can be moveable and the other stationary as described above).
The mold shown can be used to make the molded product 60 bearing a
lenticular image (of FIG. 10). Molten plastic material is shown
being introduced into the mold using arrows and via a typical gate
arrangement 90 (also shown in FIG. 12). Inside the mold is
lenticular image 70. Again, image 70 is typically produced as a
part 10a and as shown in FIGS. 3a-3c. Thus, it is noted that image
70 can have various layers as in FIGS. 3a-3c, but, for clarity and
simplicity, these layers are not shown in FIG. 11 (or, for that
matter, in FIGS. 12 and 13).
[0057] FIGS. 12 and 13 show cross-sectional views of the mold 80
(in FIG. 12, only mold portion 80b is shown) taken along lines
12-12 and 13-13 of FIG. 11, respectively. Lenticular image 70 is
also shown (again, without layering). The width of the mold cavity
between mold sections 80a and 80b can be clearly viewed in addition
to lenticular part 70. Gate 90, through which molten plastic can be
injected into the cavity, can also be seen (FIG. 12).
[0058] Referring again to FIG. 11, to make the cup bearing a
lenticular image 70, plastic can be injected in an indirect
fashion, meaning that the plastic is not injected to immediately
come in contact with or come up against the lenticular image part.
Rather, the molten plastic is first channeled into the mold at a
distance from the lenticular image, the distance in this case
roughly equal to the radius of the base of the cup. Thus, a surface
that does not require decoration (e.g., a lenticular image), such
as the bottom of a cup (as is the case here), can be utilized to
effectively minimize deleterious effects to the lenticular image.
Here, the lenticular image is placed in the mold cavity so as to
extend substantially only over what will become the frustoconical
sidewall of the finished cup. Using a design such as this, heat and
pressure associated the molten plastic can be controlled to a
greater extent, and thus, the molten plastic is prevented from
harming the lenticular image.
[0059] As a practical matter, the placement, including any angling,
of any gate(s) tend(s) to be of greater importance than the
selection of any particular type of gate (e.g., sub, hook, edge).
Gates can be positioned or angled to channel the molten plastic
into the mold at a distance from the lenticular image. This, in
turn, can serve to protect the image since, as mentioned
previously, the heat and pressure of the molten plastic entering
the mold can have deleterious effects, both on the image, as well
as the lens itself. Also, specific design aspects of the present
invention relating to molding technology (i.e., the size, placement
and angling of various items, for instance, the runners and gates)
can be determined by those of skill in the art of injection molding
depending, of course, on the particular project at hand.
[0060] Additionally, to ensure proper flow of the molten material
(as well as proper temperature, pressure and any associated
turbulence of the flow of plastic material), a suitable "mold
thickness" must be considered and designed. "Mold thickness" means
the annular area in between stationary and moveable mold portions
80a and 80b and more specifically here refers to the width of that
section of the mold cavity which ultimately forms the frustoconical
sidewall of the cup. To determine an appropriate mold thickness
requires accounting not only for the thickness of the end product
(i.e., the wall of the cup) but of the lenticular image. In short,
the lenticular image (for a typical cup of the kind described here)
has a thickness that is not insignificant when compared to the
overall mold thickness. In other words, lenticular image has a
thickness that cannot be discounted when considering heat, pressure
and turbulence of the molten plastic entering the mold cavity.
[0061] The pressure and turbulence of water exiting a hose nozzle
increases when the cross-sectional area of the hose is decreased.
Similarly, the pressure and turbulence of the molten plastic
increase as a result of the additional area taken up by the
lenticular image part in the mold. Accordingly, mold and product
design, as well as gate placement, angling and/or size, must
accommodate such factors.
[0062] An example of a molded product that can be made in
accordance with the present invention is shown in FIGS. 10-13. A
cup is shown having a wall thickness of about 82.5 mils. A typical
lenticular image (again, comprising a lens, image layer and perhaps
a substrate and/or coating layer(s) as described above with respect
to FIGS. 2a-d) has a thickness of about 14.5 mils. Thus, in a mold
designed for the production of a plastic cup having wall thickness
of about 82.5 mils, molten plastic is actually introduced (through
a channel such as the one shown in FIGS. 11 and 12) into a mold
having reduced thickness of about 68 mils. This reduced thickness
corresponds to the annular thickness of the mold cavity less the
thickness of the lenticular part.
[0063] In contrast, a typical cellular phone cover having a
thickness of about 37.5 mils and a lenticular image of about 14.5
mils would result a reduced mold thickness of about 23 mils and
thereby resulting in an increased level of turbulence within the
mold cavity. Such turbulence has been found in practice to have
deleterious effects on the lenticular image, including for example,
distortion of the interlaced image. In fact, this distortion can
take the form of melting and reflowing the ink of the printed
lenticular image. Thus, it may be necessary to redesign the mold so
as to accommodate the part thickness (which includes the thickness
of the lenticular image) so as to avoid the destructive effects of
turbulence.
[0064] The mold cavity is typically filled, or "packed" with the
molten plastic so as to produce a complete part or article. Without
such packing, a portion of the product (e.g., in this case, the
sidewall of the cup) may not form properly and/or completely. For
any given mold (again, a mold cavity can take varying shapes and
contours, as well as utilize a variety of channeling and gate
arrangements) and any given type of plastic (e.g., polystyrene)
that can be used, a specific quantity "x" of plastic is injected.
This quantity is known in the art of injection molding as a "shot"
of molten plastic.
[0065] The process of "packing" the mold cavity is monitored and
controlled here with respect to lenticular to a greater extent when
compared with other, nonlenticular molding applications. There is a
range, or "window" of quantities of molten plastic that can work to
produce a proper, final, complete part, and this range is narrower
for lenticular applications when compared to nonlenticualr
applications. When a mold is packed too little, that is, with a
quantity molten material that is less than "x", it is said to be
"short-shot" and/or underfilled. "Short-shooting" typically results
in an unfilled mold cavity, and typically, an incomplete part. When
a mold is packed too much, it is said to be "over-packed" or filled
with a quantity of plastic that is greater than "x". "Over-packing"
can result in flattening or distortion of the lenticules of the
lenticular lens. Such distortion of the lens can ultimately result
in degradation of the underlying image when the image is viewed
through the lens. In essence, a balance be must be achieved between
"short-shooting" and "over-packing" the mold to produce a complete
final injection molded article with a lenticular image attached
properly thereto.
[0066] Finally, lenticular image 70 (FIGS. 10-13), as described
earlier, can preferably include a coating (such as flood coat and
other coatings referenced briefly above) to protect the image from
the heat and pressure of the molten plastic. In addition, it has
been found that, when properly selected, the coating can also
accomplish an improved adhesion between the molten plastic and the
lenticular image part. One coating that is suitable for use in this
invention and which achieves at least these stated benefits is
"PLASTIJET XG", a solvent evaporative "silk" screen ink, available
from Sericol, Inc., of North Kansas City, Mo. It is also noted here
that the image underlying the lenticular lens (the image that can
impart an effect such as multidimensionality and/or motion) can
itself be printed using the "silk" screen ink, and in doing so,
eliminate the need for the separate step of flood-coating the
lenticular image.
[0067] In an alternative embodiment of the present invention, the
lenticular lens of the lenticular image is made in situ. In this
embodiment, at least one surface or at least one part of one
surface of one of the mold halves is shaped to impart a lenticular
lens configuration to a portion of the surface of the molded
article. In this embodiment, the image (e.g., an interlaced image
suitable for creating the illusion of motion and/or depth),
typically printed upon a suitable substrate, is positioned over the
part of the mold shaped to impart a lenticular lens configuration
to the molded article. Significantly, the image is mapped to the
lenticules of the lens. The method as described above is then
performed.
[0068] It is to be understood that the detailed description (and
accompanying drawings) relating to a cup having a frustoconical cup
is provided by way of example only, and is not to be construed in a
limited sense with respect to this invention. Indeed, molded
articles that can be made by the method of this invention include
such diverse items as: containers (for example, cups, bottles,
etc.), key chains, necklaces, charms, automobile dashboards,
cosmetic or compact disc cases, among others, including those
listed above.
[0069] The present invention has been described in terms of
preferred embodiments. Equivalents, alternatives, and
modifications, aside from those expressly stated herein, are
possible and are within the scope of the appending claims.
* * * * *