DE20023423U1 - Barrier coating application method for a container blow molding process involves application of a coating before and/or during molding of the container - Google Patents

Abstract

Containers are blow molded preferably by stretch blowing a preform inside a tool cavity. A coating medium is introduced into the blowing mold(3) before and/or during the molding stage. An independent claim is made for the process equipment including a blowing mold(3) with inlets(10,19) for a coating medium.

Description

The invention relates to a device for the production of containers by blow molding in a blow mold starting from a blank.

Is known from the DE 199 31 992 a device and a method in which a coating material is applied on the outside to the previously blown container or to the preform. A disadvantage of this is; that an independent device is required for the coating. It should also be taken into account here that, for example, a coating can only be applied to the finished-blown container at temperatures at which the material of the container does not deform.

Furthermore, document WO 99/17334 a device integrated in a stretch blow molding machine or a filling machine for coating bottles using a plasma process known inside the bottle. This method has the disadvantage that the medium to be stored in the container comes into direct contact with the coating material and thus particularly high requirements regarding of composition and consistency of the coating material.

It is also from the document GB 2 138 736 discloses a device and a method in which preforms are coated with a coating material and subsequently a blow molding process takes place. A disadvantage of this method is that the coating film while of blow molding can possibly tear open and thus only one patchy Coating of the finished blown body results. Furthermore is it also possible that a coating with different layer thicknesses on different Bodies of the body results and thus the desired Effect of the coating does not extend evenly over the entire plastic body. Here too must for the coating of the preforms provided an independent facility his.

From the document US 4,394,333 a method is known in which the gas which inflates a body in a blow molding process contains a reactive gas component which reacts with the inner wall of the preform. A disadvantage of this method is that the resulting coating must be compatible with the medium that is to be stored in the container. Another disadvantage is that the reactive gas has to be brought to a high process pressure which is customary for blow molding processes, which means that the use of a reactive gas results in special requirements for the compression and supply of the process gas.

Object of the present invention it is therefore a while avoiding the disadvantages of the known solutions simple device for the production of coated containers create.

This task is accomplished with a device solved the features of claim 1.

The manufacturing device according to the invention of containers through blow molding is done that the blow mold has at least one inlet for a coating agent and / or an outlet for that Includes coating agents. This allows the coating agent are introduced into the blow mold and too much coating agent is added Leave the blow mold again.

A device is advantageous here, at least one entry for the coating agent is provided on an element which relative to the blow mold and in particular along the blow mold axis is mobile. With such a movable element, it is possible to controlled introduction of the coating agent into the various Ensure areas of the blow mold.

An advantageous embodiment of the device is that the movable element on a Lift cylinder is arranged. This makes it possible to automate a movement of the movable element, which has at least one inlet for the coating agent includes to achieve.

It is also advantageous a control valve for the supply of the coating agent is provided. This makes it possible to Time of application of the coating agent and the exact amount of the coating agent which is introduced into the mold control and control automatically.

It is also advantageous that the blow mold has at least one inlet for a cleaning agent and the feed for the cleaning agent comprises at least one control valve. This is it possible a cleaning agent is checked into the blow mold in terms of time and quantity contribute.

Another advantageous embodiment of the Device is that the inlet for the coating agent and / or the cleaning agent comprises at least one nozzle. By using it a nozzle it is advantageously possible essentially gaseous and essentially liquid Apply coating agent finely divided into the blow mold.

The following are two exemplary embodiments described the invention with reference to the drawings.

Show it:

1 the vertical section through a first embodiment of a device for producing coated containers with a stationary spray nozzle

2 the vertical section through a second embodiment of a device for producing coated containers with a vertically movable spray nozzle.

The device 1a to 1 is made from coated beverage bottles PET, starting from a blank heated to processing temperature 2 made of PET. It has a multi-part blow mold 3 with two removable side parts 3a . 3b and a lifting and lowering base 3c on. The side parts 3a . 3b are on swiveling and lockable mold carriers 4a . 4b attached a stretch blow molding machine, not shown; the bottom piece 3c is on a lifting rod 5 attached to the stretch blow molder.

Because of the side panels 3a . 3b and the bottom piece 3c limited, essentially rotationally symmetrical cavity 6 the contour of the finished blown bottle is defined. Over the blow mold 3 or a blank used in it 2 is a liftable and lowerable, at the mouth of the blank 2 gas-tight compressible blowing nozzle 7 with a controllable blown air supply 8th arranged. The blow nozzle 7 surrounds a stretching mandrel that can also be raised and lowered 9 , the blank in the usual way in the manufacture of PET bottles before the actual blowing process 2 up to the stop on the bottom piece 3c stretches.

The bottom piece 3c has an inlet in the center 10 for a coating agent in the form of one in the cavity 6 directed spray nozzle. This is partly in the lifting rod 5 running line 11 and control valves 12 . 13 with a container 14 for a liquid coating agent and a container 15 connected for a liquid detergent. Also are in the bottom piece 3c Holes evenly distributed over the circumference 16 trained the cavity 6 connect with the environment. Through these holes 16 escapes from the cavity during stretch blow molding 6 displaced air. In the present case, excess coating agent can also over the holes 16 the blow mold 3 leave.

The device 1b to 2 differs from the device according to the figure 1a essentially in that the spray nozzle 10 at the top of a vertical pipe 17 is arranged in the bottom piece 3c is slidably mounted and by means of a lifting cylinder 18 or the like. All or part of the cavity 6 the blow mold 3 can be retracted and retracted along its central axis.

In both embodiments, the inflow of detergent and coating agent is through the inlet 10 through the control valves 12 and 13 regulated, which are preferably operated by the central control of the stretch blow molding machine.

The function of the devices 1a and 1b is the following

First is in the opened blow mold 3 a blank heated to processing temperature 2 introduced and then the bottom piece 3c raised to its working position and the blow mold 3 closed and locked. The blank 2 now sits firmly between the side panels 3a and 3b , his body in the cavity 6 and his head juts out into the open. This position is in 1 respectively. 2 shown. Now about the inlets 10 a coating agent, which can be liquid, gaseous or dusty or any mixture, into the cavity 6 the blow mold 3 brought in. Even here, if too much coating agent has been sprayed in, the excess coating agent can flow through the drains 16 from the blow mold 3 escape. The blank 2 can already come into contact with the coating agent. During the subsequent stretch blow molding process, which is caused by the pressing of the blow nozzle 7 to the mouth of the blank 2 and retracting the horizontal bar 9 in the blank 2 begins, the blank expands 2 in the cavity 6 into it. Here, too, further coating agent can be let into the space that is still left until the finished blown bottle finally contacts the inner surface of the blow mold 3 creates and absorbs deposited coating agent there. The expanding bottle thus enters its final shape directly with that in the blow mold during stretch blow molding 3 coating agent in contact. This results in a uniform and well-defined coating on the finished blown container.

In a variant of the embodiment according to the invention 1 the coating agent is additionally or exclusively over several in the peripheral region of the blow mold 3 arranged inlets indicated by dashed lines 19 in the cavity 6 introduced. In the embodiment according to 2 is the entrance 10 on the other hand on a movable element 17 , so that the inlet 10 through the interior 6 the blow mold 3 can move through. This creates a particularly even filling of the interior 6 the blow mold 3 guaranteed. The lifting cylinder 18 serves the movable element 17 in terms of the blow mold 3 to move up and down.

The control valves 12 and 13 are intended to flow the coating agent into the blow mold 3 to control the timing and to dose the coating agent. The control valve 10 also allows a detergent to be controlled in terms of time and quantity in the blow mold 3 contribute.

A cleaning can be combined after each Coating blowing or at larger intervals be made, even with the blow mold open.

The coating of the manufactured Body can for various reasons be of interest. On the one hand, this makes gas permeability possible of the container to lower or increase the barrier effect. This affects both gases those from the outer area into the inside of the container can penetrate as well as gases coming from inside the container can exit which is particularly important for beverage bottles is.

Furthermore, it is possible by means of the coating that surface finish the bottle or the color scheme of the bottle influence.

Also an additional coating on the finished blown Bottle outside the blow mold is possible the coating applied according to the invention then forms an intermediate layer.

A possible coating agent with a good barrier effect is, for example, polyphenyl alcohol in aqueous Solution.

So that the mouths of the inlets 10 . 19 The outer surface of the bottle is not visually impaired, it can be covered by inserts made of porous material or spring-loaded check valves. The holes can also 16 serve as an inlet for the coating agent.

Claims (10)

Device for producing containers by blow molding, comprising a blow mold, characterized in that the blow mold ( 3 ) at least one inlet ( 10 . 19 ) for a coating composition. The device of claim 1, wherein the blow mold ( 3 ) at least one outlet opening ( 16 ) for the coating composition. Device according to one of claims 1 or 2, wherein at least one inlet ( 10 ) for the coating agent on an element ( 17 ) is provided, which is relative to the blow mold ( 3 ) is mobile. Device according to one of claims 1 to 3, wherein at least one inlet ( 10 ) for the coating agent on an element ( 17 ) is provided, which is movable along the blow mold axis. Device according to one of claims 3 to 4, wherein the movable element ( 17 ) with a lifting device ( 18 ) connected is. Device according to one of the claims 1 to 5 , with a control valve ( 12 ) is provided for the supply of the coating agent. Device according to one of claims 1 to 6, wherein the blow mold ( 3 ) at least one inlet ( 10 ) for cleaning agents. Device according to one of claims 1 to 7, wherein a control valve ( 13 ) is provided for the supply of the cleaning agent. Device according to one of claims 1 to 8, wherein the inlet ( 10 ) for the coating agent and / or for the cleaning agent comprises at least one nozzle. Device according to one of claims 1 to 9, wherein an inlet for the cleaning agent in the middle of the bottom piece ( 3c ) the blow mold ( 3 ) arranged <.