EP2094459A1

EP2094459A1 - Preform for the production of biaxially extended plastic bottles, and plastic bottle produced from a preform

Info

Publication number: EP2094459A1
Application number: EP07818750A
Authority: EP
Inventors: Robert M. Siegel
Original assignee: Alpla Werke Alwin Lehner GmbH and Co KG
Current assignee: Alpla Werke Alwin Lehner GmbH and Co KG
Priority date: 2006-10-24
Filing date: 2007-10-05
Publication date: 2009-09-02
Also published as: WO2008049506A1; US20100028577A1; CH699063B1; MX2009004312A

Abstract

A preform (1) for the production of biaxially extended plastic bottles has a rigid, substantially elongated body (2), which at one longitudinal end thereof comprises a base (3) and the opposite longitudinal end of which is configured as a neck section (4) provided with a pouring opening (5). The preform (1) has outer and inner walls (A, I), which extend at least across a partial region of the axial length thereof and are formed by separate plastic layers. At least one intermediate layer (Z) is embedded in at least a partial region of the body (2) in a space delimited by the outer and inner walls (A, I) of the body (2), the intermediate layer extending across part of the axial length and the circumference of the body (2) and having a color that deviates from the outer or inner layers (A, I).

Description

Pref orm for the production of biaxially stretched plastic bottles and plastic bottles made from preforms

The invention relates to a preform for the production of biaxially stretched plastic bottles according to the preamble of claim 1. The invention also relates to a plastic bottle made from the preform.

The usual in the past containers made of white or stained, glass or ceramic are increasingly being replaced by plastic containers. In particular, for the packaging of fluid substances, such as beverages, household products, care products, cosmetics, etc., mainly plastic containers are used. The low weight and the lower costs certainly play a significant role in this substitution. The use of recyclable plastic materials and the generally more favorable overall energy balance during their production also contribute to promoting consumer acceptance of plastic containers, in particular plastic bottles.

The most commonly used plastic bottles are made of polyethylene terephthalate or PET or its slightly modified copolyesters and are usually produced in a so-called injection stretch blow molding process. These methods are a combination of injection molding and blow molding. In this case, a preform is first produced in an injection molding process in an injection mold. Recently, flow molding processes for producing preforms have also been proposed. The preform has a substantially elongated cylindrical body at one end thereof

Longitudinal end of a floor is formed. A support ring separates the body from a neck portion with a pouring spout. This neck portion usually already has the later shape of the bottle neck. On the outside of this neck portion threaded portions or the like are usually already formed for the determination of a closure part. After being manufactured, the preform is removed from the injection mold in a plastic injection molding process, conditioned if necessary, and introduced into a blow mold of a blow molding machine in which it is finally inflated with overpressure to the desired shape and additionally drawn with a stretching mandrel. The so biaxial stretched plastic bottle is then removed from the mold. An injection blow molding process is also already known in which the blowing process takes place directly after the injection of the preform. The preform remains on the injection mandrel, and part of the injection mold forms a section of the blow mold.

From the prior art, plastic containers already produced by extrusion blow molding are known which have differently colored areas and / or are provided with longitudinally extending decorative strips. The color graduated areas or strips generally have no technical function and serve only to change the external appearance of the plastic container. In these known plastic containers, the color-contrasting areas or strips have a relatively long transition area, in which the base color merges into the color-contrasting area or changes from this back to the base color. Sometimes this effect may be intended; however, it is usually visually less appealing and does not achieve the desired effect. This produced in Extrusionsblasverf plastic bottles with the running over a relatively long distance transitions are therefore rarely used.

Stretch-blown biaxially stretched plastic bottles, on the other hand, are always produced in one color only. For this purpose, a great deal of effort is made to provide the preforms with a uniform complete Einf coloring. Color effects are achieved at best by a subsequent coating of the plastic bottle or by the sticking of films and the like. On the other hand, there is also the desire for targeted coloring, which may have both aesthetic and functional properties in biaxially stretched plastic bottles, in particular in the PET bottles making up the bulk of the plastic bottles, in the stretch blow molding process. For example, the customer can be signaled by a targeted coloring, in which area the bottle is best taken. Targeted coloring of the plastic bottle can also be of use for subsequent processing steps, for example to highlight the labeling area or to facilitate pattern recognition for a robot-controlled transport and / or processing system. Object of the present invention is therefore to provide a preform for the production of biaxially stretched plastic bottles, which allows the production of plastic bottles with targeted color effects. The preform is intended to be producible in a conventional manner and to be further processed by stretch blow molding in the usual way. Additional technical effort and additional costs for preform production should be largely avoided. Furthermore, the object of the present invention is to provide a biaxially stretched plastic bottle which has color effects to the desired extent.

The solution to these problems consists in a preform for the production of biaxially stretched plastic bottles, which has the features mentioned in the characterizing portion of claim 1. Further developments and / or advantageous embodiments of the invention are the subject of the dependent claims. Biaxially stretched plastic bottles produced from the preform according to the invention are the subject of the claims directed thereon.

The inventive preform for the production of biaxially stretched plastic bottles has a rigid, substantially elongated body which has a bottom at one longitudinal end and the opposite longitudinal end is formed as a provided with a pouring neck portion. The preform has an outer and an inner wall, which extend over at least a portion of its axial length and layers of separate plastic are formed. At least in a partial region of the body, at least one intermediate layer which extends over a part of the axial length and the circumference of the body and a color deviating from the outer or inner layers is embedded in a space bounded by the outer and inner walls of the body having.

While preforms are used for the known from the prior art conventional multilayer plastic bottles having one or more intermediate layers which extend as uniformly as possible over the entire body of the preform, the invention provides a preform having at least one intermediate layer which extends only over a portion of the body of the preform. The intermediate layer has a different shape from the inner and outer layers. en coloring on. As a result, special optical effects, color transitions, mixed colors, 3-D effects, and effects which are dependent on the viewing angle of the observer can be achieved in the ready-blown plastic bottle.

An expedient variant of the invention provides that at least the outer layer of the body is transparent. By the color of the base material of the inner layer and the transparent outer layer and by the deviating coloring of the intermediate layer (s) additive or subtractive farm mixtures and transitions can be achieved.

Another embodiment of the invention provides that all layers of the body are transparent. As a result, color interactions of the layers with a colored filling material are possible. By different density gradients in the medium itself, this can contribute additional optical effects.

Basically, the intermediate layer need not extend over the entire circumference of the body of the preform. To simplify the production of the preform by injection molding, the at least one intermediate layer is advantageously annular and extends over the entire circumference of the body.

In a further variant of the preform according to the invention, the intermediate layer has a variable thickness over its axial and / or radial extent. While in the known preforms and the biaxially stretched plastic bottles produced therefrom a uniform wall thickness of the intermediate layer in the foreground, for example to act as a barrier layer, the invention makes the thickness variations own control to quite specific optical effects, such as 3-D effects to achieve.

For identification purposes, which can be used in particular in fully automatic processing systems with pattern recognition, it can be provided in a further variant of the invention that the intermediate layer penetrates the outer layer in the region of the bottom and / or in the region of the neck of the body. To lift off certain portions of the stretch-blown plastic bottle, the preform according to the invention may have two or more intermediate layers along the axial extension of its body, which extend annularly over the circumference of the body. By doing so, for example, the area in which the label is to be attached can be determined. It can also be signaled in this way to the consumer, where the bottle should be conveniently taken.

Since the at least one intermediate layer consists of a material which hardly or never bonds to the outer and / or the inner layer, the colored layer can easily be separated again from the remaining layers during recycling of the plastic bottle and further processed separately. This also allows the use of colored materials which have a lower food-grade level, without thereby jeopardizing the recycling of the plastic bottles.

For the cost-effective production of the inventive preform proves a multi-layer plastic injection method as appropriate. These processes are well known for the production of multilayer preforms, tested and suitable for cost-effective mass production. In contrast to the known methods, the injection process for the production of the preforms according to the invention is controlled in such a way that one or more intermediate layers are produced only in partial regions of the body of the preform. This can be achieved without major structural modifications by means of an appropriate control of the injection times and quantities of the materials for the intermediate layers) as well as the injection speeds.

Biaxially stretched plastic bottles, which are produced in a stretch blown from one of the described variants of the inventive preforms, are characterized by special optical effects. They can have color transitions, mixed colors, 3-D effects, or viewing-angle-dependent effects. The color effects can be used in conjunction with the contents of the plastic bottles, for example, for a simpler and easier determination of the level of the bottle. Further advantages and features will become apparent from the following description of exemplary embodiments of the invention with reference to the schematic figures. It shows in not to scale representation:

Fig. 1 - Fig. 6 different variants of the inventive preform.

The embodiment variants of preforms illustrated by way of example in FIGS. 1 to 6 are in each case provided with the reference numeral 1 in their entirety. They have an elongate body 2, one end of which is closed by a bottom 3, which is usually cambered. At the opposite end, the body 2 has a neck portion 4, which has a pouring opening 5. The neck portion 4 is separated from the rest of the body 2 of the preform 1 by a flange-like protruding support ring 6. On its outside, the neck portion 4 is usually provided with threaded portions 7 or the like. The body 2 of the preform 1 has an outer wall A and an inner wall I. According to the invention, the preform 1 between the two

Layers A, I at least one intermediate layer Z, which is provided only in a partial region of its extension. The intermediate layer Z may extend only over a portion of the circumference of the body 2 of the preform 1, or it may be annular. The intermediate layer Z does not have to be arranged exactly in the middle between the inner wall I and the outer wall A, but can also run more on the outer wall A or the inner wall I. The preforms 1 are produced in a multi-layer plastic injection molding process. Suitable materials for the outer and inner layers A and I are PET, polypropylene, polystyrene, HDPE, LDPE and the like. The injection point of a preform 1 on the bottom 3 of the body 2 is provided with the reference numeral 8.

1 shows a preform 1 whose intermediate layer Z has a different wall thickness in the axial direction due to specially set injection speeds. In this way, for example, a color gradient from top to bottom is possible. The bearings of the intermediate layer Z, when it begins or stops, is adjustable by the injection start and stop of the colored component, which is injected during the production of the preform with second injection unit between the two outer layers A, I. Fig. 2 shows a preform having two intermediate layers Z, which are arranged axially one above the other. This is done by a targeted start and stop the injection of the colored material with the second injection unit. In an analogous manner, more than two intermediate layers can be created.

FIG. 3 shows a preform 1 whose intermediate layer Z is arranged close to the injection point 8.

4 shows a preform 1 whose intermediate layer Z is laid on the outside by a very early addition of the colored material in the neck section 4 of the preform 1. In particular, the intermediate layer Z penetrates the outer wall A at the free end of the neck portion 4 and forms color wrinkles F.

In the preform 1 shown in FIG. 5, for example, the intermediate layer Z reaches into the injection point 8. This is achieved by the fact that in the injection nozzle already colored material is present, which attaches to the injection of the preform 1 to the inner layer or to the outer layer. On the outer wall A of the preform, the attached material is indicated by the reference symbol D. As a result, special color gradients can be achieved on the finished stretch blown plastic bottle.

FIG. 6 shows a preform 1 in which it is avoided by the longest possible injection point 8 that residues of the dyed material pass uncontrollably into the nozzle region of the injection cavity. As a result, deposits of colored material on the outer wall A of the preform 1, as are intentionally provided in the exemplary embodiment according to FIG. 5, are avoided. The long injection point 8 is finally cut off in a separate working cut.

The variants of preforms illustrated with reference to FIGS. 1 to 6 are given only by way of example. It is understood that the different variants of embodiment variants (with the exception of the combination of the variants according to FIG. 5 and FIG. 6) can be combined with one another as desired in order to produce further preforms from them. The preforms formed according to the invention can be further processed in a customary manner in a stretch blow molding process in order to produce biaxially stretched plastic bottles therefrom.

Claims

claims

1. preform for producing biaxially stretched plastic Haschen having a rigid, substantially elongated body (2) having at its one longitudinal end a bottom (3) and its opposite longitudinal end as a with a

Outlet opening (5) provided neck portion (4) is formed and having an outer and an inner wall (A, I), which extend at least over a portion of its axial length and layers of separate plastic, characterized in that at least in a portion of the body is embedded in a space defined by the outer and inner walls (A, I) of the body (2) at least one intermediate layer (Z) extending over a portion of the axial length and circumference of the body (2 ) and one of the outer and inner layers (A, I) deviating color has.

2. Preform according to claim 1, characterized in that at least the outer layer (A) of the body (2) is transparent.

3. preform according to claim 1 or 2, characterized in that all layers (a, I, Z) of the body (2) are transparent.

4. Preform according to one of the preceding claims, characterized in that the intermediate layer (Z) is annular and extends over the entire circumference of the body (2).

5. Preform according to one of the preceding claims, characterized in that the intermediate layer (Z) has a variable thickness over its axial and / or radial extent.

6. Preform according to one of the preceding claims, characterized in that the intermediate layer (Z) in the region of the bottom (3) and / or in the region of the neck portion (3) of the body (2) penetrates the outer wall (A).

7. Preform according to one of the preceding claims, characterized in that along the axial extent of the body (2) two or more intermediate layers (Z) are provided which extend annularly over the circumference of the body (2).

8. preform according to one of the preceding claims, characterized in that the at least one intermediate layer (Z) consists of a material which with the outer and / or the inner layer (A, I) bad to not connect.

9. preform according to any one of the preceding claims, characterized in that it is made injection molding method in a multi-layer plastic.

10. Biaxially stretched plastic bottle produced in a stretch blow molding process from a preform (1) according to one of the preceding claims.