U.S. patent application number 12/572888 was filed with the patent office on 2010-02-18 for process for the production of plates made of transparent plastic material with non-transparent overinjected parts.
This patent application is currently assigned to INGLASS S.p.A.. Invention is credited to Maurizio BAZZO, Afro ROSSANESE.
Application Number | 20100038819 12/572888 |
Document ID | / |
Family ID | 36088964 |
Filed Date | 2010-02-18 |
United States Patent
Application |
20100038819 |
Kind Code |
A1 |
ROSSANESE; Afro ; et
al. |
February 18, 2010 |
PROCESS FOR THE PRODUCTION OF PLATES MADE OF TRANSPARENT PLASTIC
MATERIAL WITH NON-TRANSPARENT OVERINJECTED PARTS
Abstract
Described herein is a process for the production of plates made
of transparent plastic material with non-transparent overmoulded
parts by means of a first direct injection and subsequent
compression for the formation of the transparent plate, and a
second injection for overmoulding said parts on the transparent
plate, covering the indicators or witness marks of the first
injection. Each injection can be in spots controlled in sequence,
and the second injection can be followed by a respective step of
post-compression.
Inventors: |
ROSSANESE; Afro; (Noventa di
Piave (Venezia), IT) ; BAZZO; Maurizio; (Oderzo
(Treviso), IT) |
Correspondence
Address: |
HESLIN ROTHENBERG FARLEY & MESITI PC
5 COLUMBIA CIRCLE
ALBANY
NY
12203
US
|
Assignee: |
INGLASS S.p.A.
San Polo Di Piave (Treviso)
IT
|
Family ID: |
36088964 |
Appl. No.: |
12/572888 |
Filed: |
October 2, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11047498 |
Jan 31, 2005 |
|
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12572888 |
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Current U.S.
Class: |
264/250 |
Current CPC
Class: |
B29K 2995/0025 20130101;
B29C 2045/565 20130101; B29L 2031/345 20130101; B29C 45/16
20130101; B29L 2031/7782 20130101; B29K 2995/0026 20130101; B29L
2031/3055 20130101; B29C 45/561 20130101; B29C 45/0025 20130101;
B29C 2045/0032 20130101 |
Class at
Publication: |
264/250 |
International
Class: |
B29C 45/12 20060101
B29C045/12 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 11, 2004 |
IT |
TO2004A000702 |
Claims
1-9. (canceled)
10. A pane comprising: a shaped plastic part which is transparent
and has at least one sprue mark located on an optical surface of
the shaped plastic part and occuring as a result of the use of a
direct injection-moulding process during production of the shaped
plastic part; and a covering material covering the at least one
sprue mark, the covering material having a lower transparency than
the shaped plastic part.
11. A process for producing a transparent sheet-like shaped plastic
part comprising: injection-moulding the shaped plastic part by a
direct injection-moulding process, wherein at least one sprue mark
located on an optical surface of the shaped plastic part is formed;
and covering the sprue mark with a covering material of lower
transparency than the shaped plastic part.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a Continuation of U.S. Ser. No.
11/047,498, filed on Jan. 31, 2005, and titled "PROCESS FOR THE
PRODUCTION OF PLATES MADE OF TRANSPARENT PLASTIC MATERIAL WITH
NON-TRANSPARENT OVERINJECTED PARTS," which claims priority from
Italian application number TO2004A000702, filed on Oct. 11, 2004,
the entire disclosures of which are incorporated herein by
reference.
[0002] This application also relates to U.S. patent application
Ser. No. 11/047,480, filed on Jan. 31, 2005, and titled "AN
APPARATUS AND A METHOD FOR THE INJECTION-COMPRESSION MOULDING OF
ARTICLES MADE OF PLASTIC MATERIAL WITH TWO COMPONENTS," now U.S.
Pat. No. 7,462,316, issued on Dec. 9, 2008, the contents of which
are incorporated herein by reference.
[0003] This application also relates to U.S. patent application
Ser. No. 11/047,500, filed on Jan. 31, 2005, and titled "A PROCESS
FOR THE PRODUCTION OF PLATES MADE OF TRANSPARENT PLASTIC MATERIAL
WITH NON-TRANSPARENT AREAS," now U.S. Pat. No. 7,479,244, issued on
Jan. 20, 2009, the contents of which are incorporated herein by
reference.
[0004] This application also relates to U.S. patent application
Ser. No. 11/047,483, filed on Jan. 31, 2005, and titled "A METHOD
AND AN APPARATUS FOR THE PRODUCTION OF ARTICLES MADE OF MOULDED
PLASTIC MATERIAL PARTICULARLY BY MEANS OF INJECTO-COMPRESSION," now
abandoned, the contents of which are incorporated herein by
reference.
[0005] This application also relates to U.S. patent application
Ser. No. 11/047,106, filed on Jan. 31, 2005, and titled "AN
APPARATUS AND A METHOD FOR INJECTO-COMPRESSION MOULDING OF ARTICLES
MADE OF PLASTIC MATERIAL WITH TWO COMPONENTS," now U.S. Pat. No.
7,534,102 issued on May 19, 2009, the contents of which are
incorporated herein by reference.
[0006] This application also relates to U.S. patent application
Ser. No. 11/047,104, filed on Jan. 31, 2005, and titled "A PROCESS
FOR THE PRODUCTION OF PLATES MADE OF PLASTIC MATERIAL WITH PARTS
OVERMOULDED BY INJECTION COMPRESSION," now U.S. Pat. No. 7,462,315
issued on Dec. 9, 2008, the contents of which are incorporated
herein by reference.
[0007] This application also relates to U.S. patent application
Ser. No. 11/047,481, filed Jan. 31, 2005, and titled "A METHOD FOR
THE PRODUCTION OF PLATES MADE OF PLASTIC MATERIAL WITH PARTS
OVERMOULDED BY INJECTION COMPRESSION," the contents of which are
incorporated herein by reference.
[0008] This application also relates to U.S. patent application
Ser. No. 11/046,937, filed on Jan. 31, 2005, and titled "AN
APPARATUS AND A PROCESS FOR THE INJECTION COMPRESSION MOULDING OF
ARTICLES MADE OF PLASTIC MATERIAL WITH TWO COMPONENTS," now U.S.
Pat. No. 7,540,733 issued on Jun. 2, 2009, the contents of which
are incorporated herein by reference.
FIELD OF THE INVENTION
[0009] The present invention relates to the production of articles
made of transparent plastic material, particularly but not
exclusively plates such as window panels for the automotive field
or screens for plasma televisions, with more or less limited
non-transparent areas, whether discrete or continuous, peripheral
or internal.
STATE OF THE PRIOR ART
[0010] Traditionally, such plates are produced by means of
injection moulding. The transparent material, typically
polycarbonate, is much more sensitive than other plastic materials
to lines of flow, joints, etc., so much so that, as the dimensions
of the products increase, the difficulties of injection are such
that it is impossible to eliminate some typical aesthetic and
optical defects unless very sophisticated injection systems are
provided. For items of modest dimensions, the so-called
"film-injection" system is effectively used. This system enables
many of the problems typical of these transparent plastic materials
to be solved but, as the dimensions increase, does not enable
sufficiently high levels of quality to be achieved. Furthermore,
this type of injection involves cutting of the appendage of the
film projecting from the moulded plate, said appendage having a
non-negligible mass with respect to that of the product and
involving an evident waste of material.
[0011] Furthermore, for these transparent plates, in relation to
the different applications for which they are designed (and in
particular in the case of use in the automotive sector), the
reduction of residual internal stresses ("in-mould stresses") is of
fundamental importance. These stresses tend in fact to deform the
product, altering its optical properties.
SUMMARY OF THE INVENTION
[0012] The purpose of the invention is to overcome the limitations
imposed by film-injection systems and enable an efficient
production of articles made of transparent plastic material,
particularly but not exclusively plates, with parts of
non-transparent material, as a continuous or discontinuous
peripheral edge, having optimal aesthetic and optical
properties.
[0013] With a view to achieving said purpose, the subject of the
present invention is a process for the production of plates made of
transparent plastic material with overinjected non-transparent
parts, basically characterized in that it comprises the following
steps:
[0014] providing a mould, a first moulding station with at least
one first injector, a second moulding station with at least one
second injector, said injectors being located in a position
directly corresponding to an area of the plate to be produced;
[0015] moulding said transparent plastic material by means of
injection-compression to limit the stresses on the injection spots
generating said transparent plate with indicator of injection or
witness mark; and
[0016] injecting the non-transparent plastic material within said
mould in the second moulding station via said at least one second
injector so as to overmould said parts on said transparent plate,
thus covering said indicator of injection.
[0017] The process according to the invention conveniently
envisages the use of a set of first injectors in said first
moulding station and of a set of second injectors in said second
moulding station, said first and second injectors being aligned in
a position directly corresponding to said area of the plate to be
produced.
[0018] Typically, said area may be constituted by a peripheral edge
of the plate, or else by internal areas, and possibly by the entire
extension of the transparent plate.
[0019] The injection of the transparent plastic material can
advantageously be performed according to a particular sequential
modality, and there is conveniently envisaged a step of compression
not only at the end of the step of injection of the transparent
plastic material, but also at the end of the step of injection of
the non-transparent plastic material so as to reduce sensibly
possible residual stresses of the plate.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] The invention will now be described in detail with reference
to a non-limiting example of embodiment of the process, with
reference to the annexed plate of drawings, in which:
[0021] FIG. 1 is a schematic dorsal elevation of a plate made of
bi-component plastic material obtained using the process according
to the invention;
[0022] FIG. 2 is a partially sectioned side elevation of FIG.
1;
[0023] FIG. 3 is a partially sectioned side elevation, which shows
a first step of the process according to the invention;
[0024] FIG. 4 is a cross-sectional view according to the line IV-IV
of FIG. 3;
[0025] FIG. 5 is a view similar to that of FIG. 3, which shows a
second step of the process according to the invention; and
[0026] FIG. 6 is a cross-sectional view according to the line VI-VI
of FIG. 5.
DETAILED DESCRIPTION OF THE INVENTION
[0027] FIGS. 1 and 2 of the annexed plate of drawings are schematic
representations of an example of a product made of bi-component
plastic material obtained with the process according to the
invention.
[0028] The product is constituted by a plate 1 made of transparent
plastic material, typically polycarbonate, on the dorsal face of
which there is applied a perimetral frame 2 made of non-transparent
plastic material, formed with appendages and projections 3 usable
for the assembly of the plate in the condition of use.
[0029] The process for the production of such a bi-component
product envisages two successive steps, described in what follows
with reference to FIGS. 3, 4 and 5, 6, respectively.
[0030] It should be noted that the process according to the
invention can be implemented both on a press for injection moulding
equipped with a rotating plate and on a press of the stack-mould
type with rotating central surface.
[0031] In both cases, two moulding stations will be provided, the
first designated by 7 and the second by 8, in a position
corresponding to which a mould 9 is subsequently positioned.
[0032] The first forming station comprises a half-mould 7 equipped
with a set of first injectors 4 of a generally conventional type,
with direct plugging via a respective plug 11, which can be axially
displaced between a position of closing and a position of opening
for introduction within the mould 9 of the transparent plastic
material coming, also in a way in itself known, from a hot chamber
supplied by a plasticizing system.
[0033] It should be noted that the injectors 4 are equipped with
respective ring nuts, set in substantially sealed contact with the
mould 9, the conformation of which (not illustrated or described
herein for reasons of brevity) may be of an innovative type, for an
optimal control of temperature, which forms the subject of a
parallel Italian patent application filed on the same date by the
present applicant.
[0034] The injectors 4 of the first moulding station 7 are aligned
with respect to one another and located, with respect to the mould
9, in a position directly corresponding to a peripheral area of the
transparent plate 1 to be moulded. Said peripheral area is
designated by 10 in FIG. 4, and consists of a band adjacent to one
of the larger sides of the plate 1 and contained within the
internal boundary, designated by 5 in the same FIG. 4, of the
perimetral frame 2 that will be subsequently formed in the second
moulding station 8.
[0035] In the case of the example illustrated, the injectors 4 of
the first moulding station 7 are seven in number; they are
designated in FIG. 4, respectively, by u1 the central one, by u2
and u3 the ones adjacent on opposite sides to the central injector
u1, by u4 and u5 the ones adjacent on opposite sides to the
injectors u3 and u2, and by u6 and u7 the end ones, which are
adjacent, respectively, to the injectors u4 and u5. Of course, the
number of injectors may be greater or smaller according to the
dimensions of the plate, as likewise according to their
arrangement, but the modalities for their actuation will in any
case be similar to the ones described below.
[0036] Following upon the half-closing of the mould 9, the
injectors 4 are activated so as to introduce the transparent
plastic material within the mould 9. The activation can be
simultaneous or otherwise; more conveniently, it can be performed
according to a particular sequential modality starting from the
central injector u1 towards the end injectors u6, u7, as described
and illustrated in a parallel Italian patent application filed on
the same date by the present applicant.
[0037] Even though, in the case of the example illustrated, the
injectors 4 are arranged in alignment only along the peripheral
area 10 of the plate 1, i.e., as has been said along one of its
larger sides, there are no particular limitations in providing
further injectors also along the smaller sides and also along the
other larger side of the plate 1. However, experimental tests
conducted by the present applicant have demonstrated that the
arrangement illustrated in the example is normally sufficient for
optimal filling of the cavity of the mould 9 also for plates of
large dimensions.
[0038] Of course, the injectors 4 may be located also in a position
corresponding to internal areas of the plate 1.
[0039] In the case where the plate 1 is of large dimensions, of
fundamental importance is the reduction of residual internal
stresses that can be generated, at the end of injection of the
transparent plastic material, said in-mould stresses possibly
inducing deformations and altering the optical properties of the
plate itself.
[0040] For this reason, the injection performed as described
previously in the first moulding station 7 is followed by a step of
compression of the plate 1 as a result of the complete closing of
the mould 9 against the half-mould 7. This step of post-compression
can be performed with conventional modalities: in the case where
the apparatus uses a press of the stack-mould type, this step may
be performed according to what is described in the German patent
application No. DE-A-10217584, whilst in the case where said step
of post-compression is--as will be seen in what follows--also
carried out in a position corresponding to the second moulding
station 8, it will be necessary, in the case of a stack-mould
press, to envisage specific solutions such as the ones described
and illustrated in parallel Italian patent applications filed on
the same date by the present applicant.
[0041] It should be noted that the step of compression can also be
performed simultaneously with, instead of subsequently to, the
injection step.
[0042] At the end of forming of the transparent plate 1, on its
peripheral area 10 there are identifiable the indicators or witness
marks (in the form of small craters) of the injection spots
corresponding to the nozzles of the injectors u1-u7.
[0043] The mould 9 is then transferred into a position
corresponding to the second moulding station with the half-mould 8,
represented in FIGS. 5 and 6. Also in this case, there is provided
at least one set of injectors 6 aligned along the peripheral area
10 of the plate 1, and possibly a second set of injectors 6 aligned
in a position corresponding to the opposite area (i.e., that of the
other larger side of the plate 1) as illustrated in FIG. 6. The
nozzles of the injectors 6 are identified in said figure by
"us".
[0044] The injectors 6 of the one or more series may be fewer in
number than the injectors 4 of the first moulding station 7, for
example four in number, and it is not necessary for them to be
plugging ones. These nozzles 6 may be controlled in sequence or
else with simultaneous opening.
[0045] The non-transparent plastic material injected by the nozzles
6 will come to form the peripheral frame 2, overmoulding it on the
dorsal face of the transparent plate 1 between the perimetral line
5 and the peripheral edge thereof, covering the indicators or
witness marks of the injection spots corresponding to the nozzles
u1-u7 of the first moulding station 7.
[0046] Also in this case, the injection of the peripheral edge 2
may be followed by a step of post-compression for example actuated,
in the case where the moulding apparatus uses a stack-mould press,
with the modalities described in parallel Italian patent
applications filed on the same date by the present applicant.
[0047] The process according to the invention enables all the
limitations imposed by conventional moulding systems to be
overcome, and enables an efficient production of bi-component
plates, also with transparent surfaces of large dimensions, free
from internal stresses or in any case with extremely low levels of
stress and such as to prevent deformations and alterations of their
optical properties. These effects are a direct consequence of the
peculiar characteristics of the process according to the invention,
with direct injection in multiple spots possibly controlled in
sequence for the first step and with indicators of the injection of
the first step covered by the material of the second injection.
[0048] Of course, the details of construction of the apparatus
described by way of example for the implementation of the process
may vary widely with respect to what is described and illustrated
herein, without thereby departing from the scope of the present
invention, as defined in the ensuing claims. Thus, as already
clarified previously, the parts overmoulded on the plate may differ
with respect to the example illustrated herein and may be provided
in more or less limited areas, whether discrete or continuous,
peripheral or internal to the plate, or also consist of the entire
extension of the plate itself. Furthermore, it is understood that
the term "plate" is meant to include products having any shape or
dimension whatsoever, even ones of small dimensions.
* * * * *