PLASTIC CONTAINER HAVING AT LEAST A REGIONAL SHARP-EDGED CONTAINER GEOMETRY AND PROCESS FOR PRODUCING THE PLASTIC CONTAINER

Abstract

A plastic container manufactured from a preform with a mass share of at least 80% polyester and possibly an additive from the group consisting of dyes, fillers, catalysers, additives and lubricative additives. The plastic container comprises a container neck and a container shoulder which connects with the container neck and merges into a container body closed by a container base. The container shoulder, the container base and the container body are exclusively reshaped by a 2-stage stretch blow moulding method. The polyester is a copolyester and comprises groups which originate from the monomers cyclohexanedimethanol (CHDM) and/or monoethylene glycol (MEG), terephthalic acid (TPA) or its derivatives and isophthalic acid (IPA) or its derivatives. At least a part-region of the container body and/or of the container shoulder comprises a sharp edge with a radius of less than 0.5 mm. A method of manufacturing the plastic container is also described.

Claims

1-16. (canceled)

17. A plastic container manufactured from a preform with a mass share of at least 80% polyester and possibly at least one additive from the group consisting of dyes, fillers, catalysers, additives and lubricative additives, with a container neck and a container shoulder which connects with the container neck and merges into a container body which is closed by a container base, wherein the container shoulder, the container base and the container body are exclusively reshaped by way of a 2-stage stretch blow moulding method, the polyester is a copolyester and comprises groups which originate from the monomers cyclohexanedimethanol (CHDM) and/or monoethylene glycol (MEG), terephthalic acid (TPA) or its derivatives and isophthalic acid (IPA) or its derivatives, and at least a part-region of the container body and/or of the container shoulder comprises a sharp edge with a radius of less than 0.5 mm.

18. The plastic container according to claim 17, wherein the copolyester has an intrinsic viscosity, which is measured according to ASTM D4603, of less than 0.75 dl/g.

19. The plastic container according to claim 17, wherein the copolymer has a density of 1.1 g/cm.sup.3 to 1.3 g/cm.sup.3.

20. The plastic container according to claim 17, wherein the copolyester consists of diol shares and dicarboxylic acid shares, which together result in 100% of a material quantity, wherein the diol share is 40% to 60% of the material quantity.

21. The plastic container according to claim 20, wherein a sum of the material quantity shares of cyclohexanedimethanol (CHDM) and monoethylene glycol (MEG) with respect to the diol share is 100% and CHDM has a share of 0% to 100% of the material quantity of the diol share.

22. The plastic container according to claim 20, wherein the dicarboxylic acid share consists of isophthalic acid or its derivatives and of terephthalic acid or its derivatives.

23. The plastic container according to claim 22, wherein a sum of the material quantity shares of isophthalic acid or its derivatives and of terephthalic acid or its derivatives is 100% with respect to the dicarboxylic acid share and isophthalic acid or its derivatives has a share of 10% to 60% of the material quantity of the dicarboxylic acid share.

24. The plastic container according to claim 17, wherein the preform which is inserted into a blow mould is reshaped by way of the blow moulding method in such a manner that the container shoulder, the container base and the container body of the plastic container are formed from a preform body of the preform which projects into the blow mould and is closed at one side, according to an inner geometry of a cavity of the blow mould, and the preform body is stretched along its middle axis by a factor of 2 to 4.

25. The plastic container according to claim 17, wherein the sharp edge has a radius of less than 0.3 mm.

26. The plastic container according to claim 17, wherein the plastic container is designed as one piece container.

27. The plastic container according to claim 17, wherein the plastic container comprises walls which are designed to be either single-layered or multi-layered.

28. The plastic container according to claim 17, wherein the sharp edge is shaped out at least on a part-region of a transition between the container shoulder and the container body.

29. A method of manufacturing the plastic container according to claim 17, wherein a preform body, which connects with a preform neck and is closed at one side, is stretched along a middle axis of the preform at a speed of about 1 m/s to about 3 m/s during a blow moulding method.

30. The method according to claim 29, wherein the preform body, during 2-stage stretch blow moulding method, is stretched along its middle axis by way of a stretching mandrel.

31. The method according to claim 29, wherein a fluid with a pressure of greater than 10 bar and less than 40 bar is brought into the preform which is heated to a predefined temperature for shaping out the container shoulder, the container base and the container body.

32. The method according to claim 29, wherein a blow mold with a cavity, having inner geometry for forming the container shoulder, the container base and the container body, are heated to a temperature which is greater than 10° C. and less than 100° C.

33. The plastic container according to claim 17, wherein the copolyester has an intrinsic viscosity which is measured according to ASTM D4603 of between 0.60 dl/g to 0.73 dl/g.

34. The plastic container according to claim 17, wherein the copolyester has an intrinsic viscosity which is measured according to ASTM D4603 of between 0.65 dl/g to 0.71 dl/g.

35. The plastic container according to claim 17, wherein the sharp edge has a radius of less than 0.1 mm.

Description

BRIEF DESCRPIPTION OF THE DRAWING

[0027] Hereinafter, the invention is explained with reference to the sole FIGURE, in which both a perform and a plastic container are illustrated in a schematic section.

BRIEF DESCRPIPTION OF THE PREFERRED EMBODIMENTS

[0028] The plastic container in its entirety has the reference numeral 1. It is manufactured for example in a stretch blow moulding method from an injection moulded preform which in the drawing is indicated dashed and is provided with the reference numeral 11. The plastic container 1 comprises a container neck 2 and a container body 4 which is closed with a container base, and these are connected to one another via container shoulder 3. The container shoulder 3 is separated from the container neck 2 by way of a radially projecting support ring 5 and extends up to a transition 6 to the container body 4, wherein this transition is designed in a sharp-edged manner. In the context of the present invention, sharp-edged means that the container at the transition 6 has a radius of curvature r which is smaller than 0.5 mm. For example, the radius of curvature can be only 0.2 mm or 0.3 mm. The container neck 2 herein corresponds to the neck of the preform 11 which has been manufactured in an injection moulding method. With the stretch blow moulding method, the neck of the preform 11 is located outside the blow mould and is not reshaped any further. For this reason, the container neck can comprise structures 7 which are designed in a relatively sharp-edged manner. These however are not a consequence of the stretch blow moulding method but a result of the injection moulding method which also permits the manufacture of structures with radii of curvature of less than 0.5 mm. The sharp-edged structures 7 which are on the container neck 2 and which project or recede with respect to the container shoulder 3 and/or to the container body 4 can be for example thread sections, thread furrows or the like. Whereas a plastic container 1 with a support ring 5 is represented in the drawing, it is to be understood that the device according to the invention can also be envisaged for plastic containers without a support ring.

[0029] The plastic container 1 has an axial stretching ratio of 2 to 4 with respect to an axial extension of the preform 11. An injection point which is provided with the reference numeral 12 and which results from the injection moulding method is situated on the base of the preform, said preform being indicated in a dashed manner. In this region, the preform 11 is stretched only to an insignificant extent with the axial stretching procedure during the stretch blow moulding method. The injection point 12 is therefore usually evident also on the container base of the container 1 which is completed in its stretch blow moulding. In this manner, stretch blow moulded plastic containers 1 can be identified and differentiated from plastic containers which are manufactured in another manner, for example extrusion blow moulded plastic containers which usually comprise a squeeze fold in the base region.

[0030] The plastic container 1 according to the invention is manufactured from a preform which consists to at least 80% of polyester and possibly at least one additive from the group consisting of dyes, fillers, catalysers, additives and lubricant additives. The polyester is a copolyester and comprises groups which originate from the monomers cyclohexanedimethanol (CHDM) and/or monoethylene glycol (MEG), terephthalic acid (TPA) or its derivatives and isophthalic acid (IPA) or its derivatives. The copolyester has an intrinsic viscosity which is measured according to ASTM D4603 of less that 0.75 dl/g, preferably of 0.60 dl/g to 0.73 dl/g, particularly preferably of 0.65 dl/g to 0.71 dl/g. The copolyester has a density of 1.1 g/cm.sup.3 to 1.3 g/cm.sup.3. The copolyester consists of diol shares and dicarboxylic acid shares, which together result in 100% of the material quantity, wherein the diol share is 40% to 60% of the material quantity. The sum of the material quantity shares of cyclohexanedimethanol (CHDM) and monoethylene glycol (MEG) with respect to the diol share can be 100%, wherein cyclohexanedimethanol (CHDM) has a share of 0% to 100% of the material quantity of the diol share. The dicarboxylic acid share consists of isophthalic acid or its derivatives and of terephthalic acid or its derivatives. The sum of the material quantity shares of isophthalic acid or its derivatives and of terephthalic acid or its derivatives is 100% with respect to the dicarboxylic acid share, wherein isophthalic acid or its derivatives can have a share of 10% to 60% of the material quantity of the dicarboxylic acid share.

[0031] The reshaping of the preform into the plastic container 1 according to the invention is effected exclusively in a blow moulding method, preferably a stretch blow moulding method which is of two stages. Concerning the stretch blow moulding method, the heated preform which is inserted into a blow mould is stretched with an axial stretching speed of about 1 m/s to about 3 m/s with the help of a stretching mandrel during the stretch blow moulding method. The blow moulding pressure is herein about 10 bar to 40 bar. Herein, the blow mould is kept at a temperature larger than about 10° C., but smaller than 100° C.

[0032] The sharp-edged structures which are created on the plastic container 1 have a radius of curvature which is smaller than 0.5 mm, preferably smaller than 0.3 mm, preferably smaller than 0.1 mm. The sharp-edged structures can be arranged at the transition 6 from the container shoulder 3 to the container body 4. Concerning further embodiments of the plastic container 1, alternatively or supplementarily to this, the container shoulder 3 and/or the container body 4 can at least regionally be designed with sharp-edged transitions and/or structures which have radii of curvature of smaller than 0.5 mm. Herein, the plastic container 1 can be designed in a single-layered or multi-layered manner.

[0033] The invention is described with the example of a plastic container which is manufactured in a stretch blow moulding method. The aforementioned description however merely serves for the explanation of the invention and is not to be considered as limiting. In contrast, the invention is defined by the patent claims and the equivalents which are derived by the person skilled in the art and encompassed by the general inventive concept.