Plastic container preforms and corresponding injection molds

Abstract

A preform 1 made of a plastic material adapted to produce, by stretch blow molding, bottles suitable for containing sparkling beverages such as sparkling wine, said preform comprising: a neck 2 defining a longitudinal axis X and having an internal diameter D0 of at least 17 mm and a thickness varying along said longitudinal axis X and having a minimum value of at least 4 mm; a tubular body 3 arranged below said neck 2 and having a minimum internal diameter of at least 12 mm; and a bottom 4 closing said tubular body 3 at a first end opposite a second end adjacent said neck 2, said bottom 4 having a minimum thickness of at least 3 mm. The tubular body 3 comprises a first substantially cylindrical portion 5, proximal to the neck 2, having a thickness of at least 4 mm, a length along the longitudinal axis X of at least 30 mm and a respective outer diameter having a value D1; a second portion 6, adjacent to the first portion 5, having an outer diameter gradually increasing with a frustoconical profile from value D1 to value D2, having a maximum thickness of at least 6 mm and a length along the longitudinal axis X of at least 20 mm; and at least one further substantially cylindrical portion 7, 8, 9, arranged between the second portion 6 and the bottom 4, each having a thickness of at least 6 mm.

Description

[Technical Field]

[0001] The present invention relates to a preform made of plastic material and having a bottom or base of the "champagne" type, adapted for producing containers on an industrial scale intended to be filled with carbonated drinks, and in particular to said preform adapted for producing bottles for sparkling wine.

[0002] The present invention also relates to an injection mold for producing said preform. [Background technology]

[0003] The design of the preform is determined by how the preform will be blown and the intended use of the resulting bottle, primarily: - the final shape of the bottle, - its internal volume, - the type of liquid contained, which may be highly carbonated or of average carbonated quality; - the liquid state, in which the bottle can be filled with hot or cold liquids, and - Use of bottles that can be either disposable or reusable and therefore refilled several times, provided they are recycled and sanitized. All such variables must be taken into account.

[0004] Currently, there are no commercially available bottles made from plastic for sparkling wine or other carbonated drinks, and the neck, body and base of the bottle are aesthetically similar to traditional glass bottles for sparkling wine, prosecco or champagne.

[0005] The need to develop this type of bottle made from plastic instead of glass stems from the fact that the raw materials for producing glass are at least partially in decline and the associated manufacturing process is particularly energy intensive. There are many challenges to overcome in producing such bottles from plastic, and these challenges must be addressed in the design of the corresponding preform.

[0006] For example, to obtain a plastic bottle with a "champagne" type bottom or base, it is necessary to have an optimal distribution of material, especially in the zone of the support base, and therefore different thicknesses on the bottle wall and thus on the preform. Indeed, the bottom must have a clearly specified material thickness map in terms of mechanical strength under various pressure and temperature conditions.

[0007] Furthermore, it is also difficult to produce a preform neck made of a plastic material that can withstand the forces exerted internally by the cork and externally by the metal cage after blowing the bottle, filling the bottle, and applying the cork and relative metal cage over the cork and around the neck.

[0008] One further difficulty is presented by the selection of a preform material that does not tend to dull or crystallize during cooling in the mold cavity or when subjected to stretch blow molding.

[0009] To date, all these problems have not been overcome and therefore a need is felt to produce preforms made of plastic materials that are able to overcome the aforementioned drawbacks. Summary of the Invention [Problem to be solved by the invention]

[0010] The object of the present invention is to produce a preform made of a plastic material for producing a bottle for sparkling wine or other carbonated drinks, the neck, body and bottom of which are aesthetically similar to a traditional glass bottle for sparkling wine, prosecco or champagne.

[0011] Another object of the invention is to produce a preform made of a plastic material having a neck adapted to withstand the forces exerted internally by the cork and externally by the metal cage after blowing the bottle, filling the bottle, and application of the cork and a relative metal cage over the cork and around the neck.

[0012] A further object of the invention is to produce a preform made of a plastic material with a neck and a longitudinal section below the neck, the neck being configured to obtain optimal uncorkability of a bottle blown from said preform, aesthetically similar to a traditional glass bottle for sparkling wine, prosecco or champagne.

[0013] A further object of the present invention is to produce a preform with a tubular body and a bottom designed to avoid neck formation problems, e.g. possible shrinkage, and to obtain optimally blown bottles that are thermally stable, carbonated, reusable and have a reliable "champagne" type bottom, i.e. stable on a support base.

[0014] A further object of the present invention is to produce an injection mold specifically designed to produce said preform. [Means for solving the problem]

[0015] The present invention achieves at least one of these objects, and others that will become apparent in the light of this description, by means of a preform made of a plastic material adapted for producing, by stretch blow molding, bottles suitable for containing sparkling beverages, such as sparkling wine, the preform defining a longitudinal axis X, - a neck having an internal diameter D0 of not less than 17 mm and a thickness varying along the longitudinal axis X and having a minimum value of at least 4 mm; - a tubular body disposed below the neck and having a minimum internal diameter of 12 mm or greater; - a bottom portion closing the tubular body at a first end opposite the second end adjacent the neck, the bottom portion having a minimum thickness of not less than 3 mm; and the tubular body has - a first substantially cylindrical portion located proximal to the neck and having a thickness of at least 4 mm, a length along a longitudinal axis of at least 30 mm and respective outer diameters having a value D1; - a second part adjacent to the first part and preferably distal to the neck, the second part having an outer diameter gradually increasing with a frustoconical profile from a value D1 to a value D2, a maximum thickness of at least 6 mm, and a length along the longitudinal axis X of at least 20 mm; - at least one further substantially cylindrical portion disposed between said second portion and the bottom portion, said portion having a thickness of at least 6 mm; It has.

[0016] A further aspect of the invention relates to an injection mould for producing the aforementioned preform, said mould having a plurality of mould cavities, each mould cavity being defined by cooperation of a male mould part or core insert with a female mould part having a neck insert or neck ring, a cavity insert and a gate insert; the neck insert extends along a longitudinal axis of the mold cavity to cover a first longitudinal portion of the mold cavity corresponding to a zone of the preform including both the neck and the first and second portions of the tubular body; the neck insert includes a first frustoconical projection and a second frustoconical projection at opposite ends along the longitudinal axis; a first locking element is provided for locking the male component and the neck insert together by at least contacting a side surface of the first frustoconical projection; a second locking element is provided for locking the neck insert and the cavity insert together by at least contacting a side surface of the second frustoconical protrusion; The length H1 of the first frusto-conical projection and the length H2 of the second frusto-conical projection are both measured along the longitudinal axis and satisfy the following relationship: H1+H2≧0.2×H where H is the length measured along the longitudinal axis between the flat annular surface of the mold cavity corresponding to the mouth surface of the preform and the parting line between the neck insert and the cavity insert.

[0017] Each moulding cavity is adapted to obtain the aforementioned preform.

[0018] Further features and advantages of the present invention will become more apparent upon consideration of the detailed description of illustrative, but non-exclusive, embodiments.

[0019] The dependent claims describe particular embodiments of the invention.

[0020] In describing the present invention, reference is made to the accompanying drawings, which are provided as non-limiting examples. [Brief explanation of the drawings]

[0021] [Figure 1] 1A and 1B show a side view and a cross-sectional view of a first embodiment of a preform according to the invention; [Figure 2] 3A and 3B show a side view and a cross section of a second embodiment of a preform according to the invention. [Figure 3] 1 shows a cross-sectional view of a first neck variant of a preform according to the invention; [Figure 4] 1 shows a cross-sectional view of a second neck variant of a preform according to the invention; [Figure 5] 1 shows a cross-sectional view of a portion of an injection mold for producing a preform according to the invention. [Figure 6] 1 shows an example of a bottle for sparkling wine obtained from a preform according to the present invention. [Figure 7] 7 shows a cross-sectional view of the bottom of the "champagne" type of bottle of FIG. 6. DETAILED DESCRIPTION OF THE INVENTION

[0022] Like reference numbers and letters in the figures identify like elements or components.

[0023] Referring to Figures 1-4, several examples of preforms made of plastic materials for producing bottles for sparkling wine or other carbonated beverages are shown, the neck, body, and bottom of which are aesthetically similar to traditional glass bottles for sparkling wine, prosecco, or champagne.

[0024] In all embodiments of the present invention, the preform defines a longitudinal axis X, preferably an axis of symmetry, a neck 2 having an internal diameter D0 of at least 17 mm and a thickness varying along the longitudinal axis X and having a minimum value of at least 4 mm; a tubular body 3 arranged below the neck 2 and having a minimum internal diameter of at least 12 mm; a bottom part 4 closing the tubular body 3 at a first end opposite to a second end adjacent to the neck 2, the bottom part 4 having a minimum thickness of at least 3 mm; It has.

[0025] Advantageously, a minimum thickness of the bottom 4 ensures the correct formation of a bottom with a "champagne" type shape, a minimum value for the internal diameter of the tubular body 3 allows for correct blowing of the bottle with the stretch rod, and minimum internal diameter and thickness values ​​of the neck 2 ensure correct insertion of the cork and adequate resistance to the forces exerted internally by the cork and externally by the metal cage after blowing the bottle, filling the bottle and applying the cork and metal cage over the cork and around the neck.

[0026] As used herein, a "substantially cylindrical section" refers to a section of a preform that is not perfectly cylindrical when a draft angle is provided on only the inner profile of the preform section, or on both the inner and outer profiles. As is known, a draft angle is a conicity applied to the vertical walls of an injection molded part to facilitate release of the part from the mold.

[0027] Advantageously, in order to ensure an optimal distribution of the plastic material during the stretch blow molding step of a bottle having a shape similar to that of a glass bottle for sparkling wine or prosecco or champagne, the tubular body 3 is a first substantially cylindrical portion located proximal to the neck 2 and having a thickness of at least 4 mm, a length along the longitudinal axis X of at least 30 mm and a respective outer diameter having a value D1; a second portion 6 adjacent to said first portion 5 and distal to the neck 2, the second portion 6 having an outer diameter gradually increasing with a frustoconical profile from a value D1 to a value D2, a maximum thickness of at least 6 mm, and a length along the longitudinal axis X of at least 20 mm; at least one further substantially cylindrical part arranged between the second part 6 and the bottom 4 and having a thickness of at least 6 mm; (Figures 1 and 2).

[0028] In particular, tests on openability carried out by removing corks from bottles blown from preforms according to the invention and filled with different types of sparkling wine have shown that an openability at least as effective as that obtained with glass bottles of similar shape can be obtained exclusively by providing the following characteristics of the preform: a neck 2 having an internal diameter D0 of at least 17 mm, preferably lying in the range 17 to 19 mm, and a thickness varying along the longitudinal axis X and having a minimum value of at least 4 mm, preferably lying in the range 4 to 7 mm; - said first substantially cylindrical portion 5, adjacent to the neck 2, having a thickness of at least 4 mm, preferably between 4 and 5 mm, and a length along the longitudinal axis X of at least 30 mm, preferably between 30 and 50 mm; - a second part 6 adjacent to said first part 5 and distal to the neck 2 with respect to the first part, said second part 6 having a maximum thickness of at least 6 mm and a length along the longitudinal axis X of at least 20 mm, preferably lying in the range 20 to 40 mm, the outer diameter of which gradually increases with a frustoconical profile from a value D1 to a value D2; are combined with each other.

[0029] Optimal resistance to both the torsional load and the axial opening force applied during uncoating can only be achieved by adhering to these dimensional constraints. Deformation of the plastic bottle can be achieved outside these dimensional constraints.

[0030] In the first embodiment shown in FIG. 1, the preform has two further substantially cylindrical portions 8 , 9 arranged between the second portion 6 and the bottom portion 4 .

[0031] A first further substantially cylindrical portion 8 adjacent to the second portion 6 has a first thickness of at least 6 mm and a respective outer diameter substantially equal to the value D2.

[0032] A second further substantially cylindrical portion 9, arranged between said first further substantially cylindrical portion 8 and the bottom 4, has a second thickness greater than the first thickness, preferably at least equal to 7 mm, and maintains a respective outer diameter substantially equal to the value D2.

[0033] The two further portions 8, 9 have draft angles in both the outer and inner profiles, while the first portion 5 has draft angles only in the inner profile. Such draft angles may, for example, be in the range 0°10' to 1°.

[0034] Preferably, the change in thickness between the first further substantially cylindrical portion 8 and the second further substantially cylindrical portion 9 is in the range of 0.2 to 1.0 mm.

[0035] In particular, the first thickness may be in the range of 6 to 8.3 mm, while the second thickness may be in the range of 7 to 8.5 mm.

[0036] Optionally, in this first embodiment, the second portion 6 has an inner diameter that gradually decreases with a frusto-conical profile from a value D1′ to a value D3, preferably said value D1′ being equal to the value D0 of the inner diameter of the neck 2.

[0037] However, in this first embodiment, a connecting portion 10 is always provided connecting the first further substantially cylindrical portion 8 and the second further substantially cylindrical portion 9, in which connecting portion 10 the inner diameter gradually decreases with a frustoconical profile from a value D3 to a value D4.

[0038] If a gradual reduction in diameter from a value D1' to a value D3 is not provided in the second portion 6, then in the connecting portion 10 the inner diameter gradually reduces with a frustoconical profile from a value D1' to a value D4.

[0039] According to a first variant, the length of the second further substantially cylindrical portion 9 along the longitudinal axis X is at least 15 mm and preferably lies in the range 15 to 30 mm.

[0040] According to a second variant, the length of the first further substantially cylindrical portion 8 along the longitudinal axis X is at least 20 mm and preferably lies in the range 35 to 70 mm.

[0041] According to a third variant, the length of the connecting portion 10 along the longitudinal axis X is at least 5 mm and preferably lies in the range 5 to 10 mm.

[0042] One or more of the dimension ranges of the various variants of the first embodiment may also be combined with one another in one or more further variants.

[0043] In a second embodiment shown in FIG. 2, the preform only has one further substantially cylindrical portion 7 arranged between the second portion 6 and the bottom portion 4 .

[0044] In this second embodiment, a further substantially cylindrical portion 7 is adjacent to the second portion 6 and has a thickness of at least 6 mm, preferably less than 8.5 mm, and each has an outer diameter substantially equal to the value D2.

[0045] The further portion 7 has a draft angle in both the outer and inner profile, whereas the first portion 5 has a draft angle only in the inner profile.

[0046] Such a draft angle may be, for example, within the range of 0°10' to 1°.

[0047] In the first variant of the second embodiment, between the neck 2 and the first part 5, a cylindrical extension 11 adjacent to the neck 2 and having an internal diameter equal to D0, i.e. equal to the internal diameter of the neck, and an external diameter equal to D1, i.e. equal to the external diameter of the first portion 5; an intermediate extension 12 connecting said cylindrical extension 11 to the first portion 5, the inner diameter of said intermediate extension 12 gradually decreasing with a frustoconical profile from a value D0 to a value D1′, and the outer diameter of said intermediate extension 12 being equal to D1; is provided.

[0048] Preferably, the inner diameter of the first portion 5, the inner diameter of the second portion 6 and the inner diameter of said further cylindrical portion 7 are substantially constant and equal to a value D1'.

[0049] In this first variant of the second embodiment, the thickness of the cylindrical extension 11 may be in the range of 3-4 mm, and its length along the longitudinal axis X is less than 5 mm.

[0050] Preferably, the total length of the cylindrical extension 11 and the total length of the intermediate extension 12 along the longitudinal axis X is in the range of 10 to 15 mm.

[0051] In a second variant of the second embodiment, not shown, the first substantially cylindrical portion 5 adjoins the neck 2 and is provided with neither a cylindrical extension 11 nor an intermediate extension 12. In this case, the inner diameter of the first portion 5, the inner diameter of the second portion 6 and the inner diameter of said further substantially cylindrical portion 7 are substantially constant and equal to the value D0, i.e. the inner diameter of the neck 2.

[0052] In all embodiments of the preform of the invention, one or more of the following dimensional ranges may be provided (even in all preferred variants) in order to further optimize the distribution of material during the stretch blow molding step and to improve the openability of the blown bottle after filling with sparkling wine and corking: the length of the first portion 5 along the longitudinal axis X is in the range of 30 to 50 mm, preferably in the range of 40 to 50 mm; the thickness of the first portion 5 is in the range of 4 to 5 mm; the length of the second portion 6 along the longitudinal axis X is in the range of 20 to 40 mm; - the thickness of the bottom 4 varies within the range of 3 to 6 mm, the maximum inner diameter of the tubular body 3 is in the range of 12 to 15 mm; - The maximum thickness of neck 2 is in the range of 4-7 mm, - The inner diameter D0 of the neck 2 is in the range of 17-19 mm.

[0053] Preferably, in all embodiments, taking into account the characteristics of the final shape of the blown plastic bottle, the neck, body, and base of which resemble a traditional glass bottle for sparkling wine, prosecco, or champagne, the material of the preform of the present invention can be selected to better avoid the risk of dulling and crystallization during the cooling step in the mold cavity and during the stretch blow molding operation. Experimentally, several materials have been found to be particularly suitable.

[0054] The first material option is polyethylene furanoate (PEF), which has a barrier improvement factor, or simply BIF, of 8 to 10 for oxygen, 4 for carbon dioxide, and 4 for water. This choice may not require the addition of an active or passive barrier.

[0055] A second material option is polyethylene terephthalate (PET), preferably a modified polyethylene terephthalate obtained by reacting unhydrogenated isophthalic acid with terephthalic acid and ethylene glycol. One particularly suitable material is a modified polyethylene terephthalate that provides isophthalic acid at levels up to 7 mol%, preferably in the range of 4-7 mol%, substituting for terephthalic acid.

[0056] Alternatively, another suitable polyester or copolyester such as bisphenol-free Tritan or a biopolymer with suitable barrier improvement and low crystallization rate can be used.

[0057] When using PET and filling sparkling wine into blown bottles, at least one additive, such as an oxygen scavenger, must be added to the PET to improve its barrier properties. Sparkling wine must have a maximum pressure of 3.0 bar and contain CO2 and free molecular SO2 as a preservative to prevent oxygen from entering during its 24-month shelf life.

[0058] Preferably, the polymeric material selected has an intrinsic viscosity in the range of 0.8 to 1.2 dL / g.

[0059] In all embodiments of the preform of the present invention, the neck 2 has an outer side profile along the longitudinal axis X that preferably consists of a concave central extension 14 disposed between two convex end extensions 15, 16 (FIG. 3).

[0060] In the neck variant shown in Figure 4, an outer annular groove 13 is advantageously formed in the end extension 16 of the neck 2 proximal to the tubular body 3, said outer annular groove being suitable for the insertion of a gripper for handling the preform.

[0061] Preferably, in all embodiments of the preform, the underside 17 of the neck 2 is a flat surface, in particular a completely flat surface, to improve the closure of the metal cage on the neck of the bottle.

[0062] Optionally, the weight of a preform according to the present invention is in the range of 80 to 100 grams, preferably in the range of 85 to 95 grams.

[0063] Preferably, the center of gravity of the preform according to the invention is located along its longitudinal axis X at a distance ranging from 85 to 95 mm, preferably from 88 to 92 mm, from the upper surface of the neck or from the flat annular surface of the neck mouth or opening. This central location of the center of gravity also makes it possible to optimize the formation of the blown bottle.

[0064] According to a further aspect of the invention, a particular injection mould is designed to produce preforms on an industrial scale according to any one of the above embodiments.

[0065] As is known, an injection mold has a plurality of molding cavities, each suitable for molding a preform.

[0066] As shown in FIG. 5, each molding cavity in the mold of the present invention is defined by cooperation of a male mold part 20 or core insert and a female mold part having a neck insert 21 or neck ring, a cavity insert 22, and a gate insert 23.

[0067] As can be seen in Figure 5, the shape of each mold cavity substantially corresponds to the final shape of the preform of the invention in its cooled state. The term "substantially corresponds" is justified by the possible shrinkage of the material in the mold cavity during its cooling.

[0068] Advantageously, the neck insert 21 extends along the longitudinal axis of the mould cavity so as to cover a longitudinal portion of the mould cavity corresponding to a zone of the preform including both the neck 2 and the first and second portions 5 and 6 of the tubular body 3 of the preform as described above, i.e. the neck insert 21 includes a zone of the preform from the mouth or opening of the neck to the second portion 6 included in the tubular body 3.

[0069] The neck insert 21 has at its ends a first frusto-conical protrusion 24 and a second frusto-conical protrusion 25, respectively, which are coaxial with each other and with the longitudinal axis of the moulding cavity and taper in opposite directions relative to the longitudinal axis of the cavity.

[0070] Furthermore, a first locking element 26 is provided for locking the male part 20 and the neck insert 21 together by abutting against the frusto-conical side of the first frusto-conical protrusion 24, and a second locking element 27 is provided for locking the neck insert 21 and the cavity insert 22 together by abutting against the frusto-conical side of the second frusto-conical protrusion 25.

[0071] Advantageously, to effectively contrast the high thrust on the neck insert 21 due to the injection pressure with the raised molding surface of the neck insert itself, the length H1 of the first frustoconical protrusion 24 and the length H2 of the second frustoconical protrusion 25, both measured along the longitudinal axis of the cavity, satisfy the following relationship: H1+H2≧0.2×H where H is the distance measured along the longitudinal axis between the flat annular surface of the mold cavity corresponding to the mouth surface of the preform and the parting line between the neck insert 21 and the cavity insert 22.

[0072] A further advantage can be represented by the fact that a plurality of cooling channels 28 are provided in the neck insert 21 arranged along a longitudinal portion of the molding cavity corresponding to a zone of the preform comprising the neck 2 and at least the first portion 5 of the tubular body 3.

[0073] In the example of Figure 5, the cooling channels 28 are arranged along a longitudinal portion of the molding cavity corresponding to a zone of the preform that includes the neck 2, the first portion 5 of the tubular body 3, and only a portion of the second portion 6 of the tubular body 3.

[0074] In a preferred variant, it is provided that the cooling channels 28 are present along at least 70% of the outer profile of the longitudinal portion of the mould cavity corresponding to the zone of the preform including the neck 2 and both the first portion 5 and the second portion 6 of the tubular body 3. It has been found that compliance with this condition dramatically improves the transparency of the blown bottle portion by keeping the portion of the blown bottle proximal to the neck in an amorphous state without crystallising. Indeed, in particular, at least the first portion 5 of the preform is not stretched inside the mould and remains amorphous.

[0075] Preferably, in the moulding cavity portion A corresponding only to the neck of the preform, at least one cooling channel 28, for example one or two cooling channels, is provided, arranged at a distance of not more than 5 mm, preferably 2 to 3 mm, from the outer profile of said moulding cavity portion A corresponding to the neck of the preform.

Claims

1. A preform (1) made of plastic material adapted to manufacture, by stretch blow molding, a bottle adapted to contain a sparkling beverage, such as sparkling wine, the preform defining a longitudinal axis (X): a neck (2) having an internal diameter D0 having a value greater than or equal to 17 mm and a thickness varying along said longitudinal axis (X) and having a minimum value of at least 4 mm; a tubular body (3) located below said neck (2) and having a minimum internal diameter of at least 12 mm; a bottom (4) closing said tubular body (3) at a first end opposite to a second end adjacent said neck (2), said bottom (4) having a minimum thickness of at least 3 mm; and The tubular body (3) a first substantially cylindrical portion (5) proximal to said neck (2), said first substantially cylindrical portion (5) having a thickness of at least 4 mm, a length along said longitudinal axis (X) of at least 30 mm, and a respective outer diameter having a value D1; a second portion (6) adjacent to said first portion (5) and distal to said neck (2), in which said outer diameter gradually increases in a frustoconical profile from a value D1 to a value D2, said second portion (6) having a maximum thickness of at least 6 mm and a length along said longitudinal axis (X) of at least 20 mm; at least one further substantially cylindrical part (7, 8, 9) arranged between said second part (6) and said bottom part (4) and having a thickness of at least 6 mm; The preform (1) has

2. a first further substantially cylindrical portion (8) adjacent to said second portion (6), said first further substantially cylindrical portion (8) having a first thickness of at least 6 mm and said respective outer diameter substantially equal to said value D2; a second further substantially cylindrical portion (9) arranged between said first further substantially cylindrical portion (8) and said bottom (4), said second further substantially cylindrical portion (9) having a second thickness greater than said first thickness, preferably at least equal to 7 mm, and maintaining said respective outer diameter substantially equal to the value D2; a connecting portion (10) connecting said first further substantially cylindrical portion (8) and said second further substantially cylindrical portion (9), said internal diameter gradually decreasing towards said base (4) in a frustoconical profile from a value D3 to a value D4; 10. The preform of claim 1, wherein

3. 3. A preform according to claim 2, wherein the variation in thickness between said first further substantially cylindrical portion (8) and said second further substantially cylindrical portion (9) is in the range of 0.2 to 1.0 mm.

4. 4. A preform according to claim 2 or 3, wherein the length of said second further substantially cylindrical portion (9) along said longitudinal axis (X) is at least 15 mm, preferably in the range of 15 to 30 mm, preferably wherein the length of said first further substantially cylindrical portion (8) along said longitudinal axis (X) is at least 20 mm, preferably in the range of 35 to 70 mm, and preferably wherein the length of said connecting portion (10) along said longitudinal axis (X) is at least 5 mm, preferably in the range of 5 to 10 mm.

5. 5. Preform according to claim 2, 3 or 4, wherein in the second portion (6), the internal diameter gradually decreases towards the bottom (4) in a frustoconical profile from a value D1′ to a value D3, and preferably said value D1′ is substantially equal to the value D0 of the internal diameter of the neck (2).

6. 2. The preform according to claim 1, wherein there is provided a single further substantially cylindrical portion (7) adjacent to said second portion (6) and having a thickness of at least 6 mm and said respective outer diameter substantially equal to the value D2.

7. Between the neck (2) and the first portion (5), a cylindrical extension (11) adjacent to said neck (2) and having an internal diameter equal to D0 and an external diameter equal to D1; an intermediate extension (12) connecting said cylindrical extension (11) and said first portion (5), in which said inner diameter gradually decreases with a frustoconical profile from a value D0 to a value D1' and said outer diameter is equal to D1; and is established, 7. Preform according to claim 6, wherein the inner diameters of the first portion (5), the second portion (6) and the further cylindrical portion (7) preferably remain substantially constant and are equal to the value D1'.

8. 8. The preform according to claim 7, wherein the thickness of the cylindrical extension (11) is in the range of 3 to 4 mm, the length of the cylindrical extension (11) along the longitudinal axis (X) is less than 5 mm, and preferably the total length of the cylindrical extension (11) and the intermediate extension (12) along the longitudinal axis (X) is in the range of 10 to 15 mm.

9. the length of said first portion (5) along said longitudinal axis (X) is in the range of 30 to 50 mm, preferably in the range of 40 to 50 mm; Preferably, the thickness of the first portion (5) is 5 mm or less, Preferably, said length of said second portion (6) along said longitudinal axis (X) is less than 40 mm; Preferably, the thickness of the bottom (4) varies within the range of 3 to 6 mm, Preferably, said thickness of said at least one further cylindrical portion (7, 8, 9) is less than 8.5 mm; Preferably, the maximum inner diameter of the tubular body (3) is in the range of 12 to 15 mm; Preferably, the maximum thickness of the neck (2) is in the range of 4 to 7 mm; Preform according to any one of the preceding claims, wherein the inner diameter D0 of the neck (2) is preferably in the range of 17 to 19 mm.

10. The preform is - polyethylene furanoate (PEF), polyethylene terephthalate (PET), preferably modified polyethylene terephthalate obtained by reaction of non-hydrogenated isophthalic acid with terephthalic acid and ethylene glycol, in particular modified polyethylene terephthalate obtained by replacing said terephthalic acid with isophthalic acid at a level of up to 7 mol %; another suitable polyester, preferably with a low crystallization rate, - bisphenol-free copolyesters such as Tritan, or - Biopolymers with adequate barrier improvement and low crystallization rate made of a polymer material selected from A preform according to any one of claims 1 to 9, wherein the polymeric material preferably has an intrinsic viscosity in the range of 0.8 to 1.2 dL / g.

11. 11. A preform according to any one of claims 1 to 10, wherein the profile of the outer side of the neck (2) has a central concave extension (14) between two convex end extensions (15, 16) along the longitudinal axis (X), and preferably an annular outer groove (13) is formed in the end extension (16) of the neck (2) proximal to the tubular body (3) and is suitable for inserting a gripper for handling the preform.

12. 12. Preform according to any one of the preceding claims, wherein the lower surface of the neck (2) is a flat surface.

13. 13. A preform according to any one of claims 1 to 12, wherein the centre of gravity of the preform is at a distance (G) along the longitudinal axis X from the flat annular surface (18) of the mouth or opening of the neck in the range of 85 to 95 mm, and preferably the weight of the preform is in the range of 80 to 100 grams.

14. 14. An injection mould for producing a preform according to any one of claims 1 to 13, said mould having a plurality of moulding cavities, Each mold cavity is defined by cooperation of a male part (20) or core insert and a female part having a neck insert (21) or neck ring, a cavity insert (22), and a gate insert (23); The neck insert (21) is said neck (2) having an internal diameter D0 of at least 17 mm and a thickness that varies along said longitudinal axis (X) and has a minimum value of at least 4 mm; the first portion (5) of the tubular body (3) having a substantially cylindrical shape and a length along the longitudinal axis (X) of at least 30 mm, and the second portion (6) of the tubular body (3) having a length along the longitudinal axis (X) of at least 20 mm, wherein the outer diameter gradually increases in a frustoconical profile from the value D1 to the value D2; extending along a longitudinal axis of the mold cavity to cover a first longitudinal portion of the mold cavity corresponding to a zone of the preform including both the neck insert (21) comprises a first frustoconical projection (24) and a second frustoconical projection (25) at two ends along the longitudinal axis, respectively; a first locking element (26) for locking the male part (20) and the neck insert (21) together, the first locking element (26) abutting at least the frustoconical side of the first frustoconical projection (24); a second locking element (27) for locking the neck insert (21) and the cavity insert (22) together, the second locking element (27) abutting at least the frustoconical side surface of the second frustoconical projection (25); The length H1 of the first frustoconical projection (24) and the length H2 of the second frustoconical projection (25), both measured along the longitudinal axis, satisfy the following relationship: H1+H2≧0.2×H where H is the length, measured along the longitudinal axis, between a flat annular surface of the mold cavity corresponding to the surface of the mouth of the preform and the parting plane between the neck insert (21) and the cavity insert (22).

15. 15. The injection mould according to claim 14, wherein a plurality of cooling channels (28) are provided in the neck insert (21), the plurality of cooling channels (28) being arranged along a second longitudinal portion of the mould cavity corresponding to a zone of the preform including the neck (2) and at least the first portion (5) of the tubular body (3), preferably the cooling channels (28) being present along at least 70% of the outer profile of the first longitudinal portion of the mould cavity corresponding to a zone of the preform including the neck (2) and both the first portion (5) and the second portion (6) of the tubular body (3).

16. 16. The injection mold according to claim 15, wherein at least one cooling channel (28) is provided in the mold cavity portion (A) corresponding to the neck of the preform, at a distance of 5 mm or less, preferably 2 to 3 mm, from the outer surface of the mold cavity portion (A) corresponding to the neck of the preform.

17. 17. An injection mould according to any one of claims 14 to 16, wherein each moulding cavity has a shape that substantially corresponds to the final shape of a preform according to claim 1.

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