Preform or container made of a thermoplastic material and method for increasing the crystallinity of the thermoplastic material

Abstract

The invention relates to a preform (10) or container made of a thermoplastic material, comprising at least one wall section (12) made of the thermoplastic material, extending between an outer surface (14) and an inner surface (16), characterized in that the wall section (12) between the outer surface (14) and the inner surface (16) has at least one geometric shape (20) made of the thermoplastic material with a higher crystallinity than the thermoplastic material of the wall section (12) outside the geometric shape (20). The invention thus provides a preform and a container made of thermoplastic material with further improved material properties, which is flexibly applicable.

Description

[0001] The invention relates to a preform or container made of a thermoplastic material and a method for increasing a crystallinity of the thermoplastic material.

[0002] Containers, such as bottles, can be manufactured from preforms made of thermoplastic materials using stretch blow molding processes. Preforms made of thermoplastic material can first be produced using an injection molding process. The preforms are then thermally conditioned and subsequently biaxially stretched in a stretch blow molding process. Certain areas of the preforms or containers sometimes require special material properties, which can, for example, relate to increased or reduced strength, crystallinity, crack resistance, or a reduction of internal material stresses. However, conventional stretch blow molding processes often do not allow the material properties of certain areas of the preforms or containers to be specifically influenced or modified.

[0003] EP 3763628 A1 discloses reducing or preventing internal material stresses outside the neck area of ​​a container by crystallizing the thermoplastic material. Crystallization occurs through the settings during thermal conditioning of the corresponding area of ​​the container.

[0004] The object of the invention is to provide a preform and a container made of thermoplastic material with further improved material properties and a method for increasing the crystallinity of a thermoplastic material which can be used flexibly.

[0005] The problem is solved by the features of the independent claims. Advantageous further developments are the subject of the dependent claims and the following description.

[0006] In a preform or container made of a thermoplastic material, comprising at least one wall section made of the thermoplastic material which extends between an outer surface and an inner surface, it is provided according to the invention that the wall section between the outer surface and the inner surface has at least one geometric shape made of the thermoplastic material with a higher crystallinity than in the thermoplastic material of the wall section outside the geometric shape.

[0007] The invention provides a preform or container made of thermoplastic material, in which the thermoplastic material of a wall section forms a geometric shape that has a higher crystallinity than the thermoplastic material outside the geometric shape in the wall section. In addition to the fluctuations in crystallinity in the material of the preform or container generated by the thermal conditioning of the preform, geometric shapes with increased crystallinity can thus be arranged in the wall sections that are independent of the crystallinity profile in the thermoplastic material generated by the thermal conditioning. These geometric shapes cannot be generated by the thermal conditioning of the preform, but can be produced, for example, by the targeted heating of the thermoplastic material using a laser.This allows precisely positioned geometric shapes to be flexibly created within the thermoplastic material of the wall section, with which the material properties in sub-areas of the thermoplastic material can be adjusted.

[0008] Increasing the crystallinity of the thermoplastic material means increasing the order of the molecules within the thermoplastic material. The molecules can rearrange themselves during laser heating, thus increasing the crystallinity compared to the surrounding thermoplastic material of the wall section.

[0009] By increasing crystallinity, the geometric shape can exhibit different material properties than the thermoplastic material outside the geometric shape. For example, by providing the geometric shape, the strength, crack resistance, or the magnitude of the internal material stresses can be adjusted throughout the entire wall section. This allows, for example, the same or improved properties, especially strength, to be achieved for containers or preforms with less material.

[0010] This allows the properties of the base to be influenced, for example, in push-up bases. Furthermore, a reinforced base ring can be provided for corresponding containers. Using the reinforced base ring can save material on the container. For petaloid bases, for example, the base feet can be reinforced.

[0011] The geometric shape can be embedded in the wall section as a visibly defined geometric shape. The geometric shape can, for example, be visibly distinguished from the adjacent material due to its increased crystallinity. For example, the crystallinity can create a cloudiness in the thermoplastic material of the geometric shape, while the thermoplastic material surrounding the geometric shape, which has a lower crystallinity, can be transparent. The geometric shape can thus be visually distinguished from the surrounding thermoplastic material. The sharp boundary can be understood as a transition from the transparent material to the cloudy material.

[0012] Furthermore, the geometric shape can, for example, be arranged at a distance from the inner surface and the outer surface of the wall section, so that thermoplastic material with a lower crystallinity than the crystallinity of the geometric shape can be arranged between the inner surface or the outer surface and the geometric shape. However, this does not rule out the possibility that the geometric shape can extend, for example, to the inner surface and / or to the outer surface. For example, it is conceivable that the geometric shape begins at the outer surface and extends to the inner surface. Furthermore, it is conceivable that the geometric shape extends from the inner surface to in front of the outer surface without reaching the outer surface. Finally, it is also conceivable that the geometric shape extends from the outer surface to in front of the inner surface without reaching the inner surface.

[0013] It is also conceivable that the crystallinity may vary within the geometric shape with increased crystallinity. If multiple geometric shapes are present, the increased crystallinity may differ between at least some of the shapes. Alternatively or additionally, the crystallinity profile may differ between at least some of the geometric shapes.

[0014] For example, stress peaks at sharp edges on the container or preform, which could lead to breakage of the preform or container material during a stretch blow molding process, can be reduced using the geometric shapes. This allows for smooth transitions in the material stress distribution.

[0015] The thermoplastic material can be, for example, polyethylene terephthalate (PET). However, it can also be made of another material.

[0016] According to one example, it is conceivable that the geometric shape can be formed as a reinforcing and / or stiffening structure in the wall section.

[0017] This allows a reinforcement or stiffening structure made of the same material as the wall section itself to be arranged within the thermoplastic material of the wall section. The reinforcement or stiffening structure made of the thermoplastic material with increased crystallinity can thus be embedded in the wall section. This avoids the need to create reinforcement or stiffening structures, for example, by varying the thickness of the wall section or adding additional components.

[0018] According to a further example, it is conceivable that the geometric shape may have a lattice, honeycomb or net shape.

[0019] For example, a lattice, honeycomb, or net-like geometric shape can be embedded in the wall section. As explained above, the geometric shape can be spaced apart from the inner and outer surfaces. The lattice, honeycomb, or net shape can provide reinforcement for the wall section of the preform or container without the use of additional material. The lattice shape can, for example, influence top load and internal pressure stability.

[0020] Furthermore, the geometric shape can, for example, be arranged at least partially in a preferably stretch-blown thread, at least partially in an injection point of a preform and / or at least partially in a bottom center, in particular a bottle base region, of a container.

[0021] This allows geometric shapes with increased crystallinity of thermoplastic material to be created in the thread, at the injection point, and / or the bottom center. These geometric shapes can reinforce the thread or reduce internal material stresses at the injection point or bottom center.

[0022] For example, in the area of ​​a bottle bottom, stiffeners can be incorporated within the material to prevent stress cracks in the area of ​​the bottom of the container.

[0023] Furthermore, threads or container mouths produced using a blow-trimming process can be equipped with the geometric shapes, particularly after the thread or container mouth has been produced. This can, for example, increase the thermal stability of the thread or container mouth. This can be particularly advantageous in hot-fill applications when mechanical forces are exerted on the mouth by a closure after filling.

[0024] The geometric shape can, for example, be distorted by a stretching factor, wherein the stretching factor represents a rectification of the geometric shape during a stretching, in particular biaxial stretching, of the geometric shape during a forming of the preform into a container.

[0025] For example, a preform can have a geometric shape distorted by the stretch factor arranged in a wall section, which is then straightened after the preform is stretched into a container. For example, the geometric shape explained above at the injection point of a preform can be transformed into a geometric shape at the bottom center of the container through stretching. In this way, small geometric shapes can be provided on a preform with little time expenditure, which can then be enlarged through stretching. This can reduce the time required and, at the same time, the costs of producing the geometric shapes for the containers.

[0026] The invention further relates to a method for increasing the crystallinity of a thermoplastic material in at least one region of a wall section of a preform or container, comprising at least the following steps: providing a preform or container made of thermoplastic material; providing position data of a region on the preform or container; wherein the following step is carried out according to the invention: heating the thermoplastic material of the wall section of the preform or container with a laser based on the information for generating the geometric shape in the wall section between an outer surface and an inner surface of a wall section of the preform or container, wherein the laser increases the crystallinity of the thermoplastic material for generating the geometric shape through the targeted heating, so that the thermoplastic material of the geometric shape has increased crystallinity.

[0027] By selectively heating the thermoplastic material in the wall section, the material properties of sub-areas of the wall section can be modified without additional structures that alter the contour or shape of the preform or container. Using a laser for heating, geometric shapes can be created with dimensions that are within the range of the dimensions of the laser's focal point. This allows for finely structured geometric shapes made of thermoplastic material with high crystallinity to be created in the wall section, which cannot be produced by heating during thermal conditioning.

[0028] Further advantages and effects, as well as further developments of the process, arise from the advantages and effects, as well as further developments of the preform or container described above. To avoid repetition, reference is made to the previous description in this regard.

[0029] According to one example, it is conceivable that the heating can be carried out before forming the preform into a container and / or after thermal conditioning of the preform for forming into a container.

[0030] The geometric shape can then be incorporated into the wall section before stretching. The wall section has a greater thickness before stretching, making it easier to incorporate the geometric shape into the wall section than in the finished container.

[0031] According to a further example, it is conceivable that the geometric shape can be produced on the preform with a stretching factor, wherein the stretching factor represents a rectification of the geometric shape during a stretching, in particular biaxial stretching, of the region during a forming of the preform into a container.

[0032] Furthermore, for example, the geometric shape can be formed as a reinforcing and / or stiffening structure in the wall section and / or as a lattice, honeycomb or net shape.

[0033] The geometric shape can, for example, be arranged on a wall section of the preform, which is formed by forming into a thread or base center, in particular a bottle base area, of the container, or at least partially comprise an injection point of the preform. Alternatively, the geometric shape can, for example, be created at least partially in a thread or base of the container.

[0034] In a further example, it is conceivable that the laser can produce a first geometric shape with a first crystallinity using a first laser intensity and a second geometric shape with a second crystallinity different from the first crystallinity using a second laser intensity, wherein the first laser intensity can preferably differ from the second laser intensity.

[0035] This allows for smooth transitions to be created between areas of different crystallinity, thus avoiding jumps in the strength of the material.

[0036] The invention is described below using an exemplary embodiment with reference to the accompanying drawings. They show: Fig. 1 a schematic representation of a preform; Fig. 2 a schematic cross-sectional view of the preform; Fig. 3a, b a schematic representation of another example of a preform and a container; Fig. 4a, b a schematic representation of a container with a lost neck area; and Fig. 5 a flow chart of the procedure.

[0037] The preform or container is designated in its entirety by the reference numeral 10, as in Fig. 1 shown.

[0038] The preform 10 or container has a wall portion 12 extending between an outer surface 14 and an inner surface 16 radially to a longitudinal axis 22 of the preform 10. The inner surface 16 may adjoin and delimit an interior space 18 of the preform 10. A thickness of the wall portion 12 may therefore correspond to a thickness of the wall of the preform 10.

[0039] Between the outer surface 14 and the inner surface 16, the preform 10 has a geometric shape 20. The geometric shape 20, like the wall section 12, can be made of a thermoplastic material. However, the thermoplastic material from which the geometric shape 20 can be made has a higher crystallinity than the thermoplastic material of the wall section 12. The material can be clouded by the increased crystallinity and can visually stand out from the surrounding material. The geometric shape 20 can therefore be visually demarcated from the surrounding material, among other things. Furthermore, the thermoplastic material with the increased crystallinity can have increased rigidity, which can be greater than the rigidity of the surrounding thermoplastic material.

[0040] As in Fig. 2, the geometric shape 20 can be arranged at a distance from both the inner surface 16 and the outer surface 14. This means that the geometric shape 20 can be arranged inside the wall section 12. The geometric shape can thus be manufactured without removing material from the outer surface 14 or the inner surface 16.

[0041] The preform 10 or container has a greater wall thickness than the finished container. After stretching, the wall thickness is reduced by the stretching process. The geometric shape 20 remains between the inner surface 16 and the outer surface 14 during and after the stretching process.

[0042] The wall section 12 can be arranged at various positions on the preform 10 or container. This is, for example, Fig. 3a and Fig. 3b.

[0043] Fig. 3a again shows a preform 10 having a lattice-like geometric shape 20 on a wall section 12. Furthermore, the preform 10 may have geometric shapes 20 at an injection point 28, at which the material of the preform 10 was injected into a mold in an injection molding process, which are designed as reinforcement structures to reduce internal material stresses after stretching. This is shown in Fig. 3b. The injection point 28 is arranged at a bottom center 30 of the container shown in FIG. 3b. The reinforcement structures can extend along the bottom center 30.

[0044] Furthermore, the comparison between the Fig. 3a and Fig. 3b shows that the lattice-like geometric shape 20 on the preform 10 is also biaxially stretched during stretching to form the container. The geometric shape 20 on the preform 10 is therefore more densely packed than on the container.

[0045] The geometric shape 20 can extend in the wall section 12 at a distance from the inner surface 16 and the outer surface 14. Furthermore, it is conceivable for the geometric shape 20 to extend from the outer surface 14 to in front of the inner surface 16 without reaching the inner surface 16. It is also conceivable for the geometric shape 20 to extend from the inner surface 16 to in front of the outer surface 14 without reaching the outer surface 14. Furthermore, the geometric shape 20 can also form both a part of the outer surface 14 and / or a part of the inner surface 16.

[0046] During the production of the geometric shape 20, for example, using a laser, only a relatively small volume or a relatively small area of ​​the preform 10 needs to be treated, in particular heated with a laser, in order to increase the crystallinity of the thermoplastic material of the geometric shape 20. By biaxially stretching the preform 10 into a container, the volume or area is automatically expanded to the size required for the container.

[0047] Furthermore, the container can be Fig. 3b, the thread 26 may have a geometric shape 20. The geometric shape 20 may stabilize or reinforce the thread 26.

[0048] Particularly in applications where a neck region 24 of the preform 10 is lost after the container is manufactured, the thread 26 can be reinforced, which in this example was created by stretching the preform. These applications are particularly advantageous for hot filling of the finished container.

[0049] Furthermore, the geometric shape 20 can already be created in the wall region 12, which is formed into the thread 26 by the stretching process. Alternatively, the geometric shape 20 can be created after the preform 10 has been stretched into a container, at the thread 26 produced by the stretching process.

[0050] The method 100 for producing a preform 10 or container is described in the flow chart according to Fig. 5 is explained in more detail.

[0051] In a step 102, a preform 10 or container made of thermoplastic material is first provided. The preform 10 can be produced, for example, by an injection molding process, and the container can be produced from a preform 10 by a stretch blow molding process or a mold-filling process.

[0052] In a further step 104, information about a geometric shape 20 is provided. The information may include, for example, position data of the geometric shape 20 on the preform 10 or container and data about the contour of the geometric shape 20. Steps 102 and 104 may be performed simultaneously or in any order.

[0053] In a further step 106, following steps 102 and 104, the geometric shape 20 is created on the preform 10 or container using a laser. For this purpose, at least one region of the thermoplastic material of the preform 10 or container can be heated with the laser. The region can be arranged in the wall section 12 of the preform 10 or container between an outer surface 14 and an inner surface 16. The geometric shape 20 is created by the laser based on the information. For this purpose, the laser can, for example, heat regions such that they correspond to the information and the geometric shape 20 is created in the wall section 12.

[0054] Furthermore, the laser can optionally distort the contour information using a stretching factor and introduce the distorted contour into the wall section of a preform 10 as a geometric shape 20. The stretching factor corresponds to a distortion of the wall section 12, which occurs through the stretching, in particular biaxial stretching, of the preform 10 into a container. The geometric shape 20 can be straightened by stretching.

[0055] Heating with the laser further crystallizes the already crystallized thermoplastic material in the heated areas of wall section 12. This means that the crystallinity of the thermoplastic material is increased in the heated areas. If the thermoplastic material is PET, for example, the degree of crystallization can be increased from 20% to 40% to a degree of crystallization between more than 40% and 80%.

[0056] Increasing the degree of crystallization or crystallinity can cause the thermoplastic material to become cloudy. The geometric shape 20 can therefore visually stand out from the surrounding thermoplastic material.

[0057] Furthermore, increasing the degree of crystallization can stiffen the thermoplastic material of the geometric shape 20. Thus, the geometric shape 20 can act as a reinforcing structure without requiring additional material or a change in the thickness of the wall section 12.

[0058] The laser can create the geometric shapes 20 in various areas of the preform 10 or container. For example, a thread 26 or a base center 30 of the container can each be provided with at least one geometric shape 20. Furthermore, an area of ​​a preform 10 can be provided with geometric shapes 20 that, after forming, forms a thread or a base center of the container. For example, the laser can create geometric shapes 20 at an injection point 28 of a preform 10. After stretching, the geometric shapes are then arranged at the base center 30 of the container.

[0059] The steps explained above can be performed after thermal conditioning of the preform 10 for forming into a container. The preform 10 can therefore already have a temperature profile with which the forming of the preform 10 into a container can be carried out. This can save energy when using the laser, since a slight heating of the material may already have taken place. This can facilitate the creation of the geometric shape 20.

[0060] The laser can further generate a first geometric shape 20 with a first crystallinity using a first laser intensity. The laser can generate a second geometric shape 20, for example, with a second crystallinity that differs from the first crystallinity. A second laser intensity can be used, which can differ from the first laser intensity. This allows smooth transitions between regions of different crystallinity to be created, thus avoiding jumps in the strength of the material.

[0061] The example described above does not limit the invention in any way. Rather, the invention can be modified in many ways. All of the features of the invention described above can be essential to the invention alone or in combination with one another. List of reference symbols 10 preform 12 wall section 14 Exterior surface 16 Interior surface 18 Interior 20 geometric shapes 22 Longitudinal axis 24 lost neck area 26 threads 28 Injection point 30 Soil Center QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This 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

[0000] EP 3763628 A1

[0003]

Claims

[1] Preform (10) or container made of a thermoplastic material, comprising at least one wall section (12) made of the thermoplastic material extending between an outer surface (14) and an inner surface (16), characterized by that the wall section (12) between the outer surface (14) and the inner surface (16) has at least one geometric shape (20) made of the thermoplastic material with a higher crystallinity than in the thermoplastic material of the wall section (12) outside the geometric shape (20). [2] Preform (10) or container according to claim 1, characterized by that the geometric shape (20) is formed as a reinforcing and / or stiffening structure in the wall section (12). [3] Preform (10) or container according to one of claims 1 or 2, characterized by that the geometric shape (20) has a lattice, honeycomb or net shape. [4] Preform (10) or container according to one of the preceding claims, characterized by that the geometric shape (20) is arranged at least partially in a preferably stretch-blown thread (26), at least partially in an injection point (28) of a preform (10) and / or at least partially in a bottom center (30) of a container. [5] Preform (10) or container according to one of the preceding claims, characterized by in that the geometric shape (20) is distorted by a stretching factor, wherein the stretching factor represents a rectification of the geometric shape (20) during a stretching, in particular biaxial stretching, of the geometric shape (20) during a forming of the preform (10) into a container. [6] Method (100) for increasing a crystallinity of the thermoplastic material in at least one wall section (12) of a preform (10) or container, comprising at least the following steps: - providing (102) a preform (10) or container made of thermoplastic material; - providing (104) information about a geometric shape (20) to be produced in a wall section (12) of the preform (10) or container; characterized by - Heating (106) the thermoplastic material of the wall section (12) of the preform (10) or container with a laser based on the information to create the geometric shape (20) in the wall section (12) between an outer surface (14) and an inner surface (16) of a wall section (12) of the preform (10) or container, wherein the laser increases a crystallinity of the thermoplastic material to create the geometric shape (20) through the targeted heating, so that the thermoplastic material of the geometric shape (20) has an increased crystallinity. [7] Method (100) according to claim 6, characterized bythat the heating (106) is carried out before forming the preform (10) into a container and / or after thermal conditioning of the preform (10) for forming into a container. [8] Method (100) according to one of claims 6 or 7, characterized by that the geometric shape (20) is produced on the preform (10) with a stretching factor, wherein the stretching factor represents a rectification of the geometric shape (20) during a stretching, in particular biaxial stretching, of the geometric shape (20) during a forming of the preform (10) into a container. [9] Method (100) according to one of claims 6 to 8, characterized by that the geometric shape (20) is formed as a reinforcing and / or stiffening structure in the wall section (12) and / or with a lattice or mesh shape. [10] Method (100) according to one of claims 6 to 9, characterized bythat the geometric shape (20) is arranged on a wall section (12) of the preform, which is formed by the forming to a thread (26) or base center (30), in particular a bottle base region, of the container or at least partially has an injection point (28) of the preform, or that the geometric shape (20) is at least partially produced in a thread (26) or base of the container. [11] Method (100) according to one of claims 6 to 10, characterized by in that the laser produces a first geometric shape (20) having a first crystallinity using a first laser intensity and a second geometric shape (20) having a second crystallinity different from the first crystallinity using a second laser intensity, wherein the first laser intensity preferably differs from the second laser intensity.

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