DE102010015019A1 - Premold for producing e.g. polyethylene terephthalate bottle, utilized for filling beverage, has hollow body comprising outer and inner surfaces, where region with absorption or reflection for thermal radiation is arranged on surfaces - Google Patents

Abstract

The premold has an elongated, one-sided closed hollow body (20) made of thermoplastic resin and exhibiting outer and inner surfaces (40, 42). The hollow body comprises a molded opening region (25) with an opening (23) at an end. A region (30) with increased absorption or reflection for thermal radiation is arranged on the outer and inner surfaces. The region is coated with an absorbing or a reflective material, where the coating consists of carrier solution with colored pigments. An independent claim is also included for a method for manufacturing a premold from thermoplastic resin.

Description

The present invention relates to a preform and a method for producing a preform according to the features of the preambles of claims 1 and 5.

State of the art

In the production of containers, for example PET bottles for beverage filling, various manufacturing processes are currently used. In the two-stage stretch blow molding process, so-called preforms are heated to a defined process temperature and shaped by stretch blow molding. During the forming process occurs a self-consolidation of the plastic material used. The process temperature is crucial here. The effect of self-consolidation is primarily used to optimize the wall thickness distribution of the container.

Normally, the temperature profile in the circumferential direction of the usually rotational preform is uniform and varies depending on the process only in the longitudinal axis of the preform. In the production of asymmetrical, for example, oval, containers, however, in addition to the temperature profile in the longitudinal direction adapted to the container design temperature profile in the circumferential direction is applied to the preform ("Preferential Heating"). The exposure of the preform with a desired temperature profile is currently realized by the targeted use of thermal radiation, such as infrared radiation (IR).

With the standard IR heating modules, it is not easy to give the preform a radial temperature profiling. Also, the sharpness of the axial profiling is limited by today's means. In the area of a heating section, a typical requirement for preferential heating is therefore to specify a precisely defined uneven temperature distribution in a circumferential direction of the preforms.

DE 10 2007 016 028 A1 describes a heating section in which, in at least part of the heating power is coordinated to the rotational movement of the preforms cyclically changed. This is achieved in that at least one heating element arranged in the region of the heating section is connected to a controller which prescribes a time-varying heating power coordinated with a rotational movement of the preforms.

For the preferential heating is thus an optional equipment of the heating sections, for example, with a control o. Ä. Necessary. Conventional heating modules with IR emitters can generally not be used for this or must be retrofitted accordingly.

One problem in particular is that different preforms require different temperature profiles, so that the machine would always have to be changed over. Especially with small preforms, it is difficult to achieve the desired temperature profiles by adjusting the radiator.

The object of the invention is a targeted cost-effective heating of certain regions of a preform, for example for the production of asymmetrical or oval container in which preferably conventional heating modules can be used without conversion measures.

The above object is achieved by a preform and a method for producing a preform comprising the features of claims 1 and 5. Further advantageous embodiments are described by the subclaims.

description

The basic idea here is to treat the preform in the production, before heating or between two heating processes on its surface so or to change so that it shows a different absorption behavior or reflection behavior in different areas.

The invention relates to a preform made of plastic. The preforms are used to make containers by heating and stretch blow molding the preform. The preform is an elongated, one-sided closed hollow body made of a thermoplastic material having an outer and an inner surface. It has a shaped mouth area at the open end. Below the turn, an annular support edge may be provided.

According to the invention, the preform has on the outer and / or the inner surface at least one region with changed / differing heat radiation absorbing or reflecting properties in comparison to the remaining surface.

In particular, it is an area with an increased absorption or reflection for thermal radiation. This is achieved, for example, by coating the preform in the defined area with an absorbent or a reflective material.

If it is a heat radiation absorbing coating, then the preform will be more heated in these areas. In the subsequent stretch blow molding process, the more heated areas can be stretched more. This is particularly helpful in the production of asymmetrical or oval containers.

On the other hand, if it is a thermal radiation reflective coating, the preform will remain cooler in these areas and will expand less in the stretch blown process.

For example, the preform is printed in defined areas with an IR absorber or with an IR reflector, vapor-deposited or otherwise coated.

According to a preferred embodiment, the coating consists of a carrier solution with colored pigments. For example, by means of a carrier solution, it would be possible to apply color pigments which are barely visible in the visible range but have IR-absorbing properties. This would be suitable, for example, the dye Lumogen IR1050. The coating can be done for example with a printer (inkjet printer), a brush, a pressure roller, with adhesive, by spraying, vapor deposition, screen printing, electrostatic, etc.

According to a further embodiment of the invention, the region with the changed absorption or reflection properties has a specifically mechanically modified surface, in particular a modified structuring, for example in the form of a defined roughness.

It is for example possible to change the surface of the preform with fine laser spots, needlesticks o. Ä. Targeted that thereby in the IR oven, in particular due to a smaller wall thickness, a larger porosity o. Ä., Another absorption behavior of the treated Places results. However, care should be taken that the treatment only affects the inner or outer layer. In particular, no continuous pores, holes o. Ä. Should arise because then the pointed-shaped container would also have holes. Such preforms would be v. a. unsuitable for the production of beverage bottles.

According to another embodiment, an area with a roughened surface is already produced in the production of the preform in the injection mold. The injection mold can for this purpose have a partial area in which the surface is not polished but is structured. This structuring is reflected on the manufactured preform. The mechanically altered surface has different absorption and reflection properties than the surrounding smooth, unstructured areas.

The invention further relates to a process for producing a preform made of thermoplastic material for use in the production of containers by stretch blow molding, wherein in particular oval and / or asymmetric containers are produced.

First, a preform is produced by the conventionally known methods, for example by injection molding. Meanwhile or subsequently, the inner and / or outer surface of the preform is selectively changed, so that the preform in at least one area has different heat radiation absorbing or reflecting properties.

In particular, as already described, the preform is provided in the at least one region with a coating of an infrared-absorbing or an infrared-reflecting material.

Furthermore, a regulation can be provided which controls the coating of a preheated preform, in particular the layer thickness and the area in which the coating is applied, on the basis of its temperature profile.

According to one embodiment of the invention, the preform is first heated in a heating furnace by radiators. Subsequently, the temperature and / or the wall thickness of the preform is determined by sensors. Based on the measured values, the amount and the layer thickness of the coating agent to be applied are calculated with absorbing or reflecting properties and the preform in the corresponding areas is provided with the calculated amount of coating agent.

It is important that the change of at least one area of the preform must not interfere with the subsequent container (in particular blow-molded bottles) for the customer. This means that the dye used must preferably not be visible in the light.

In the case of targeted material weakening by means of lasers, needles, etc., care must also be taken to ensure that the containers produced from such preforms are nevertheless tight.

figure description

In the following, embodiments of the invention and their advantages with reference to the accompanying figures will be explained in more detail. The size ratios of the individual elements to each other in the figures do not always correspond to the real size ratios, as some shapes are simplified and other shapes are shown enlarged in relation to other elements for ease of illustration.

1 to 3 show various embodiments of a preform.

For identical or equivalent elements of the invention, identical reference numerals are used. Furthermore, for the sake of clarity, only reference symbols are shown in the individual figures, which are required for the description of the respective figure. The illustrated embodiments are merely examples of how the device or method of the invention may be configured and are not an exhaustive limitation.

1 shows a first embodiment of a preform 10a , The preform 10 . 10a is an elongated, one-sided closed hollow body 20 with an outer surface 40 and an inner surface 42 , So he has a closed end 22 and on the opposite side an open end 23 with a shaped mouth area 25 on.

Below the mouth area in an annular support edge 26 intended. According to further embodiments, not shown, any type of preform comes 10 made of thermoplastic in question. In particular, it is not necessary that the preform 10 a support edge 26 has, as well as preforms 10 can be used from which after the stretch-blowing container, in particular bottles without this so-called "neck ring" are produced.

The preform 10a points below the support ring 26 an area 30 with changed surface properties, ie the surface of the preform 10a is in the area 30 compared to the rest of the preform 10a changed in its physical properties. In particular, the area shows 30 due to the changed surface increased absorption or reflection of thermal radiation compared to the remaining surface areas of the preform 10a , This is done, for example, by coating the surface of the preform 10a with an absorbing or reflecting means in the defined area 30 reached.

Is it the area 30 for example, an area 30A with increased absorption properties, then this will result in heating of the preform 10a For example, by irradiation with IR emitters that the preform 10a in these areas 30A more heated. In a subsequent blow molding process, the preform can 10a in that area 30A in contrast to the remaining surface of the preform 10a be deformed more or better.

2 shows a second embodiment of a preform 10b , In this case, the surface of the preform is 10b in two areas 30 changed parallel to the longitudinal axis of the container, for example, to produce an asymmetric container.

In the embodiment shown, it is the area 30 around an area 30R with increased reflection properties. Will the preform 10b irradiated, then he will be in these areas 30R less heated and is in a subsequent blow molding process in the areas 30R less malleable.

3 shows a third embodiment of a preform 10c , Here is an elongated area 30 changed, extending from the support edge 26 extends to the closed end of the preform.

According to another embodiment, not shown, has a preform 10 two exactly opposite elongated areas 30 on. The stretch blow molding process results from a modified preform 10 an oval container.

The invention has been described with reference to a preferred embodiment. However, it will be apparent to those skilled in the art that modifications or changes may be made to the invention without departing from the scope of the following claims. In particular, the invention is not limited to the shown symmetrical preforms with a support rim or "neck ring". The invention can be used in any kind of preform, including preforms without "neck ring", asymmetric preforms o. Ä.

LIST OF REFERENCE NUMBERS

10

preform

10a

preform

10b

preform

10c

preform

20

hollow body

22

closed end

23

open end

25

mouth area

26

supporting edge

30

Area with changed surface properties

30A

Area with increased absorption for heat radiation

30R

Area with increased reflection for heat radiation

40

outer surface

42

inner surface

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102007016028 A1 [0005]

Claims (10)

Preform ( 10 ) made of plastic for the production of containers by heating and stretch blow molding of the preform ( 10 ), wherein the preform ( 10 ) an elongated, one-sided closed hollow body ( 20 ) of a thermoplastic material having an outer surface ( 40 ) and an inner surface ( 42 ), which is at the open ( 23 ) End a shaped mouth area ( 25 ), characterized in that the preform ( 10 ) on the outer and / or the inner surface ( 40 . 42 ) at least one area ( 30 ) having increased absorption or reflection for thermal radiation. Preform ( 10 ) according to claim 1, wherein the area ( 30 ) is a coating with an absorbent or a reflective material. Preform ( 10 ) according to claim 2, wherein the coating consists of a carrier solution with color pigments. Preform ( 10 ) according to claim 1, wherein the area ( 30 ) has a specifically mechanically modified surface, a smaller wall thickness, a structuring or a greater porosity. Process for producing a preform ( 10 ) of thermoplastic material for use in the manufacture of containers by stretch blow molding, wherein the preform ( 10 ) an elongated, one-sided closed hollow body ( 20 ) is made of a thermoplastic material, which at the open end ( 23 ) a shaped mouth region ( 25 ), characterized by the following steps: • producing a preform ( 10 ) and • deliberately changing the surface of the preform ( 10 ), so that the preform ( 10 ) in at least one area ( 30 ) has different heat radiation absorbing or reflective properties. Method according to claim 5, wherein the preform ( 10 ) in the at least one area ( 30 ) is provided with a coating of an absorbent or a reflective material. Method according to claim 5 or 6, wherein the application of the coating in the region ( 30 ) with a printer, a brush, a pressure roller, by spraying, vapor deposition, screen printing or electrostatic. Method according to one of claims 6 to 7, wherein a control is provided, the coating of a preheated preform ( 10 ) due to its temperature profile controls. Method according to claim 8, wherein • the preform ( 10 ) is first heated in a heating oven by radiators; The temperature and / or the wall thickness of the preform ( 10 ) is sensory determined; On the basis of the measured values, the quantity and the layer thickness of the coating agent to be applied are calculated with absorbing or reflecting properties, and the preform is 10 ) in the fields of ( 30 ) is provided with the calculated amount of coating agent. Method according to claim 5, wherein at least one area ( 30 ) of the preform ( 10 ) is mechanically modified so that this area ( 30 ) has a changed absorption or reflection behavior.

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