FR2673567A1 - Method and device for applying a layer of a different material on an internal or external part of a moulded component - Google Patents

Abstract

The invention relates to a method and a device for selectively bonding, by melting, a covering of different material to the inner or outer surface of a cylindrical component having a closed end, or a part of this component, such as a standard threaded stopper (cap) for a container. <??>This system uses a standard assembly forming a die (12) in an injection moulding machine (14), and the covering device (16) advances a film (28) of the said different material between the part having cores (24) and the part having cavities (22) of the die (12) in the position in which the latter is open; that part of the film (28) which is used to form the covering is cut out from the film before the latter has advanced to the start of the next moulding cycle.

Description

The present invention relates to a method and a device for depositing

a layer of a different material on an internal or external part of a molded part More particularly, this invention relates to the coating of a closure member such as a stopper

standard thread.

There are different methods to deposit

a layer of a different material on a molded part.

In the field of container closures, it has been

posed the problem of depositing a sealing material

softer or more elastic on the inner surface

of a stopper formed of a harder material, and this since the installation of cork linings

on metal bottle caps.

More recently, it has been found desirable to melt bond the softer sealant.

with the cap harder This was generally done.

Usually the hard material plug is compression molded first and then the softer sealant is introduced into the plug and shaped by molding techniques.

by compression, well known. Variants of this process

dice consist of molding the softer or more elastic sealant into an end cavity of a core, followed by molding the harder material of the plug into the mold cavity

surrounding the nucleus.

Deposits of different materials on closures for purposes other than creating a sealing surface have hardly been

not been carried out.

The present invention relates to a method and a device for depositing a different material on the inner part or the outer part of a closure member during injection molding of this member. The method and the device can be used to coat the inner part with A parison being injection molded such that when the parison is blow molded into a container, the inner part or the outer part of the container is coated. The method and apparatus of this invention also allow

to selectively coat the internal surface or the surface

this external only of the upper part of a bou-

Closure chon The main purpose of filing a

such a melted layer consists in creating an impermeable surface

gas-resistant or chemically resistant to protect the product packaged in the container For example it is known that vinylidene chloride copolymers defined by the trade designation SARAN have low permeability to gases and liquids and are therefore suitable for their resistance

chemical and to form gas barriers.

In an application to a closure member, this creates an oxygen barrier in order to reduce

alteration or destruction of a pharmaceu-

tick or food Other materials such as a copo-

polypropylene polymer can be used to form a barrier to prevent contact or

oppose penetration by different gases and liquids

Also the molten coating can be advantageous.

to create for the cork a different effect of colo-

ration or configuration.

In its broadest aspects, the process provides a means for depositing a different material

on the surface of a tubular part closed at one end

mated and being injection molded The die of the molding machine has opposing and aligned mold parts and the process includes the following steps

A) Opening of the molding machine.

B) Passage of a film of different material

between the parts of the mold.

C) Close the molding machine and

imprisonment of the film between the parts of the mold.

D) Injecting a plastic material into the mold and molding the part with a layer of the different material fused together with a surface

of the room.

A finished coated part is ejected in the opening step A), and in the step B), the film

is advanced from a take-up roll to a take-up roll.

The mold has a cavity side and a side-

core so that when the plastic

is injected into the mold in step D) through

diary from the cavity side, different material be bonded

by fusion with the interior surface of the part.

When the plastic material is injected into the mold through the core side, the different material is fused together with the outer surface of the part. Preferably, the part of the film which will cover the part is cut while closing the part. molding machine in step C) Preferably, a peripheral cutting edge provided on the cavity side pushes the

film towards the core side, which also advantageously comprises

sement an edge or peripheral cutting blade which crushes the film and extrudes it so as to apply it against

the peripheral cutting edge provided on the cavity side.

It may not be necessary to coat the skirt of the cap so that the coating can be limited to the top of the cap In this case, the cavity side of the mold is divided into a cavity base and a cavity insert of such so that the cavity insert is axially separated from the cavity base during opening step A), and the film is passed between the cavity base and the cavity insert in step B) When the base the cavity insert and the cavity insert are closed during the closing of the machine in step C), part of the film is cut so as to cover only the closed end

of the cap.

The device according to the invention combines a coating device with a die assembly, usable in an injection molding machine The die assembly comprises a cavity mold, comprising at least one cavity, and a mold

core, comprising at least one core opposite the cavity.

Means comprising coincident pins and supports are provided for moving the core mold.

relative to the cavity mold from an or-

verture in which a molded part is ejected into a closed position in which the part is molded The coating device comprises an advancement means for passing a film of

different material between the molds when they are

wind in their open position A notching means is provided for cutting a part of the film which is

adjacent to the peripheries of the nucleus and cavity.

As a result, when the part is molded, it is simultaneously coated with the different material which fuses together with a surface of the part. The advancement means comprises a take-up roll and a take-up roll, with a drive system on the roll. Preferably the film is cut by blades protruding from the cavity mold and the core mold and which score the film by extrusion. A shearing action can also be used to effect the cutting operation When only the upper part of the film is cut. a closure member is to be coated, the cavity mold comprises a cavity base and a cavity insert, which are separated along a radial plane when the cavity mold and the core mold are brought into their open position The film formed of the dissimilar material is disposed between the cavity base and the cavity insert, the cutting action occurring between the cavity base members.

and cavity insert.

Other characteristics and advantages of the invention will be demonstrated in the following section.

the description, given by way of non-limiting example,

with reference to the accompanying drawings in which:

Figure 1 is a perspective view showing the assembly

die forming wheel which is installed in a conventional injection molding machine equipped with a coating device which comprises means for advancing a film of different material between the open parts of the mold; Figure 2 is a plan view, partly in section, showing a single mold cavity and a single core of the device of Figure 1, with means for injecting the plastic material through the cavity side of the die of the mold; the film of different material is advanced to this open position; Figure 3 is a view similar to Figure 2 and showing the die assembly in its closed position with the film of dissimilar material trapped between the cavity and core sides after being scored and cut in the closing operation; Figure 4 is a view similar to Figure 3, after the plastic material has been injected into the mold from the cavity side so as to melt bond with the inner surface of the plug being formed; Figure 5 is a partial sectional view taken in

the area surrounded by a circle in Figure 4 and my-

Treating a preferred form of the invention to cut the film of different material by opposing blades which act to score and extrude the film into the gap between adjacent cutting surfaces; Figure 6 is a view similar to Figure 4 and showing the plug being formed with the plastic material injected through the core side of the mold such that the film of different material melt covers the surface outer cap; Figure 7 is a view similar to Figure 2 and showing a molten cavity mold of the forming assembly

matrix, its base part and its insert part being spaced

cured in the open position of the die to allow the film of different material to pass between the two parts of the cavity mold so that the film is cut to coat only the upper part of the plug; Figure 8 is a view similar to Figure 7 with the cavity mold closed after cutting the film during die closing; Figure 9 is a view similar to Figure 8 and

showing the plug which has been extruded from the side-

mold cavity so as to coat the inner surface of the upper part of the stopper; Figure 10 is a view similar to Figure 9 and showing the plug being formed by injection

of the plastic material through the side-

core of the mold to coat the outer surface of the top of the stopper; Figure 11 is a view similar to Figure 2, the

mold parts of the die being opened and confi-

Figure 12 is a view similar to Figure 11 and showing the die in its closed position with the film cut and stretched to conform to the shape of the core;

Figure 13 is an enlarged view of the part 13 in -

reed by a circle in Figure 12 and showing the parai-

bran which has been injection molded from plastic through the cavity side of the mold, the film being fused to the inner surface of the parison; and

Figure 14 is a partial view of a sulfur mold

flage into which the core of Figures 11 to 13 has been inserted, the container having been blow molded and the figure showing the liner extending over

the inner surface of the container.

We will now make a detailed description

lée preferred embodiments of the invention.

Referring to Figure 1, the device 10 according to the invention comprises the combination of an assembly forming a die 12, suitable for use.

in a suitable injection molding machine 14

system, and a coating device 16.

The die assembly 12 comprises a mold having a cavity side 18 and a core side 20. The die assembly comprises means

classics such as pins and supports, not shown

felt, to ensure alignment and displacement of the cavity side and the core side with respect to each other from an open position ejecting part, shown in Figures 1 and 2, into a position closed molding shown in Figures 3 and 4, these means acting in cooperation with the elements of the injection molding machine 14 for opening and closing the machine, injecting material

plastic melted in the mold, etc. The number of cavities

tees 22 provided in the cavity side 18 and the cooperating cores 24 which are located in the core side 20 varies from machine to machine and depending on the product to be molded. Typically, when a closed end tubular part is to be used. molded, several horizontal, and vertically spaced, rows of cooperating cavities and cores are provided.When container caps are to be molded, it is common to have

matrices from 32 to 64 cavities and cores.

The coating device 16 comprises a supply spool 26 of different material in the form of a continuous strip or film 28 The term "different" is used to define a material which is different from the plastic material forming the part to be molded, which is in the form of a stopper or closure member 30 of a container, as shown in Figures 4 and 6 The different material is fused with the surface of the part being molded so as to impart a particular property by the piece As previously mentioned, a copolymer designated by SARAN acts as a barrier to a gas, normally oxygen, to prevent spoilage of the product in the container on which the stopper is placed Other materials such as foils can be used as barriers or heat transmitters Papers and laminated suits can be used for marking, decoration, coloring and a nalogue. The film 28 is unwound from the supply reel 26 and it passes successively over upper and lower guide rollers 32 and 34 before being wound up on the receiving reel 36 driven by a motor 34 The supply reel 26, the guide rollers

32 and 34 and the take-up reel 36 are rotatably mounted.

It should be noted that although the brackets 40 are shown to be mounted on the cavity side of the die or die, it should be noted that while the consoles 40 are shown to be mounted on the cavity side of the die or die. the molding machine, they can be mounted on the core side or have independent mounting means

and appropriate.

Referring to Figure 2, the die assembly 12 is shown in an open position in which a previously molded part would be ejected. Film 28 passes between the cavity side 18 and the core side 20 of the mold and can be ejected. be driven by the motor 38 in the direction of the take-up reel 36 in order to present an unused part of the film

for coating in the next molding cycle.

A peripheral cutting edge 42 is provided on the cavity side 18 for cutting or notching the film 28 when the die 12 is closed upon closing the molding machine. Referring to Figure 3, the die has been closed by bringing the cavity side 18 of the mold into contact with the core side 20 of the mold, with the film 20 interposed between the aforementioned sides, this film having

been stretched over core 24.

Figure 4 shows the plastic

of which the part is formed, this material having been injected

through conduit 44 in the direction of the arrow and distributor 46 to mold the stopper In the process, the film 28 was pushed to conform to the shape of the core 24 and was fused together with the inner surface of the closed end tubular stopper 30 Peripheral cutting edge 42 has cut or notched the film by extrusion such that when the molding machine is opened to the position shown in Figures 1 and 2, the workpiece 30 is ejected by being disengaged from the continuous web. In a preferred embodiment of the invention shown in Figure 5, the peripheral cutting edge 42 extends not only from the cavity side 18 but also from the core side 20 so that when the die-casting machine injection and the die are brought into the closed position, the edges

cutting 42 extrude the film 28 into the recesses

adjacent elements 48 to perform the cutting action.

A series of scoring surfaces or ribs 42 'exert a similar extruding action on the film 28 by upsetting it into subsequent recesses 48', the main function of the series of ribs 42 'being to absorb the molding pressure. between the mold

cavity 18 and the core mold 20.

Figure 6 shows the die assembly in the molding position similar to the

Figure 4, except that the pouring pipe and the

striker 46 'have injected the plastic material through the core side 20 such that the film 28 has been pushed to conform to the shape of the cavity to cover, or fusion bond with the outer surface of the cavity.

plug 30 being formed.

In many applications, a coating of the top of the part, particularly in the case of a plug, is sufficient to fulfill the intended function, for example to act as a barrier preventing the passage of a gas or preventing corrosion by a liquid, or else to create a particular type of index on the plug In Figures 7 to 11 is shown a matrix 12 comprising it

a split cavity mold 18 which is provided with a part-

separate base 50 and a separate insert part 52.

With this arrangement, as shown in Figure 7,

when the injection molding machine and die

these are located in their open position, the insert part 52 of the cavity is axially separated from the base part 50 of this cavity so that the strip of different material 28 is drawn between the aforementioned separate parts When the molding machine and die are closed, cavity mold parts

approach each other so that a peripheral edge

cutting rique provided on the base part 50 of the cavity cooperates with the insert part of the cavity to cut the film This cutting system can be in the form shown in Figures 2 to 4 or else

in the form of opposing peripheral cutting edges.

as shown in Figure 5 In Figure 7 is shown a cutting edge 54 directed inward and of the shear type, this edge being provided on the base part 50 of the cavity and cooperating with a cylindrical part 56 provided on insert portion 52 of the cavity to exert a shear-type cutting action As shown in Figure 8, when the molding machine is fully closed, the shearing action of the complementary cutting surfaces 54 and 56 produces a separation of the part which has been fused with the plug 30 being

molded with respect to the continuous part of the material film

different axle 28 Figure 9 shows, analogously to Figure 4, the plastic material being injected into the cavity part of the mold 18

via the pouring duct 44 and the distribution

striker 46 so that the film 28 is fused with the inner surface of the top of the stopper 30 Alternatively, the film 28 may be fused with the outside of the top

plug 30 as shown in Figure 10, by injection

tion of the molten plastic through

of the pouring duct 46 'in the core 24.

The method and the device according to the invention allow the deposition of a different material on a cylindrical part with closed end, in the form of a coating of a parison being injection molded, of such a kind. so that the parison can be blown in a next step to produce a container having an outer or inner coating Figures 11 to 14 show the sequence of molding and blowing the parison as a coated container Figure 11 shows the molding machine in its open position, the elements of the die and of the coating device being the same as in the previous embodiments, except

that, since the parison has a cylindrical part

that having a height greater than that of the closed end cylindrical pieces previously described, an additional film guide plate 58 has been incorporated into the coating device between the core side and the die cavity side. different material is engaged in the device

cover 16 of the core side 20 of the guide plate

dage 58 to help direct the film to en-

expand the core 24 'of the parison when the die 12 is closed in the injection molding machine from the open position of Figure 11 to the closed molding position of Figure 12.

cutting elements or similar devices of the

tions previously can be used to separate

part of the film of his band in this process.

When the plastic material is injected

through the distributor 46 in the side-

mold cavity, the parison 30 'is provided with a coating

ment 28 internally fused as shown

in Figure 13 As is common in machinery

In conventional injection and blow molding, the core 24 'is removed from the cavity side 18 of the injection mold during the next opening cycle to the position of Figure 11 and is brought into alignment with a mold. blow molding 60 to blow form a container 62 in the next molding cycle as shown in Figure 14 The container

62 is thus provided with an interior surface 28 covered

fusion kills as indicated.

The coating of an injection molded closure cap shown in Figures 2-10 and an injection molded parison shown in Figures 11-14 show the variety of closed-ended cylindrical parts which can be coated by the process and the process. combination of die and coating device according to this

invention.

Claims (14)

1 Process for depositing a different material on the surface of a part being molded, said part comprising a closed end, a confi- forming a tubular assembly and being molded in an injection molding machine having aligned and opposed mold parts, characterized in that that it includes the steps of. A) opening said molding machine; B) passing a film of said different material between said mold parts; C) closing the molding machine and trapping said film between said mold parts; and D) injecting a plastic material into said mold and forming sea said part with a coating of said different material ferent fused to a workpiece surface. 2 Method according to claim 1, characterized in that, in step A), a part is ejected and in step B), said film is fed from a reel. debtor to a take-up reel. 3 Method according to claim 2, characterized in that the mold parts comprise a cavity side and a core side and, in step D), the plastic material is injected into the mold through the side- cavity and said different material is fused together with the interior surface of said part. 4 The method of claim 3, characterized in that said part formed in step D) is a parison and said parison is ejected on a rod of core and said core rod and parison are intro- pumped into a blow mold where a container is formed formed by blowing, its internal surface being coated with said different material. Method according to claim 2, characterized in that said mold parts comprise a side- cavity and a core side and in step D) the plastic material is injected into the mold through the core side and said different material is bonded by fusion with the outer surface of said part. 6 The method of claim 5, characterized in that said part formed in step D) is a parison and said parison is ejected on a rod of core and said core rod and parison are intro- picks in a blow mold where a container is formed by blow molding, its outer surface being coated of said different material. 7 A method according to claim 1, characterized in that a part of said coating film of said part is cut in step C. 8 A method according to claim 7, characterized in that said mold parts comprise a cavity side and a core side and the part of said film is cut in step by a cutting peripheral edge provided on said cavity side supporting said film against said side-core. 9 The method of claim 8, characterized in that the part of said film is cut by opposing and aligned cutting edges located on said side- cavity and said side-core. Method according to claim 7, characterized in that said mold parts comprise a side- cavity and a core side and said cavity side is divided into a cavity base and a cavity insert, said cavity insert being axially separated from said cavity base during step A), said film passing between said base of cavity and said cavity insert in step B), said cavity base and said cavity insert being closed in step C) by cutting a portion of said film to coat only the closed end of said part in step D). 11 The method of claim 10, characterized in that the part of said film is cut by a peripheral cutting edge located on said cavity base. pressing said film against said cavity insert. A method according to claim 11, characterized in that the part of the film is cut by cutting edges aligned and located in opposite positions on said cavity side and said core side. 13 The method of claim 1, characterized in that said cavity mold and said core mold are configured so as to form a closure member for a container, said closure member comprising a cap provided with an upper part, a skirt ring finger extending downward from the peri- artery of said upper part and comprising means for connection with a container, and in that the part formed in step D) is a closure member provided with a coating of different material fused together sion with a surface of said plug. 14 A combination of a set forming ma- trice usable in an injection molding machine and a coating device for depositing a coating Of a different material on a generally tubular, closed end part which is being molded in said die assembly, a combination characterized in that: said die assembly comprises a cavity mold having at least one cavity; a core mold comprising at least one core located opposite said cavity; and means for moving said core mold relative to said cavity mold from an open position in which a molded part is ejected into a closed position in which said part is soft lée; said coating device comprising advancing means for passing a film of different material between said molds when in said open position; and scoring means for cutting a portion of said film in an area adjacent to the peripheries of said core and said cavity; said closed end tubular part being molded in said molds with a coating of different material. rent bonded by fusion with a surface of said part. Combination according to Claim 14, characterized in that said means for advancing film include a take-up reel, a take-up reel trice and a means for driving said take-up reel when said molds are in an open position. 16 Combination according to claim 14, characterized in that said notching means include an annular blade protruding outwardly erment of said cavity mold to come into contact with said core mold when said molds are present. in their closed position. 17 Combination according to claim 16, characterized in that it comprises an annular blade projecting externally from said core mold to push said film into contact with said annular blade. projecting outwardly from said cavity mold when that said molds are in their closed position. 18 Combination according to claim 14, characterized ized in that said cavity mold comprises a cavity base and a cavity insert which separate along a radial plane when said cavity mold and said core mold are in their open position and said advancement means position the film of ma- different material between said cavity base and said cavity insert. 19 Combination according to claim 14, characterized in that said cavity mold and said core mold are configured to mold an organ- for closing a container, said closure member comprising a stopper provided with an upper part, an annular skirt directed downwards from the periphery of said upper part, comprising means for connection with a container, said generally tubular and closed end piece which has been so molded being a plug provided with a coating of different material which is fused together with an over- face of said plug.