Container made of PET and / or rPET for liquid or semi-liquid articles or similar articles, typically referred to as LDP

Abstract

The invention relates to a container (1) obtained by blow molding or stretch blow molding of a preform (19) made of polyethylene terephthalate (PET), said container comprising: a body (5); a shoulder (4) in an extension of the body (5) at an upper end of the body; a neck (2) in the extension of said shoulder (4), said neck (2) being open and forming a mouth (3) of a final container (1) formed by said preform (19); and a bottom (6) housed at the lower end of the container (1) to extend, the container (1) being intended to receive liquid or semi-state articles, such as in particular dairy products, or the like, typically indicated by the English abbreviation LDP of Liquid Dairy Products, Liquid Dairy Products, dispensed in a cold chain or at (sterile) normal temperature and having a capacity of less than or equal to 150 ml; the container (1) is characterized in that the height of the container (1) from the opening (3) to the bottom (6) of the container is less than or equal to 120 mm; furthermore, the ratio, which is defined as the ratio between the outer diameter of the main body (5) and the outer diameter below the neck part (2), is between 1.3 and 2.3, and the height of the neck part (2) is less than 15 millimeters. The invention also relates to a preform for producing a container according to the invention, and finally to a mould for producing such a container.

Description

Technical Field

[0001] The field of the invention relates to the design and manufacture of containers from plastic preforms. The invention relates more particularly to the design of a container made of plastic material, more precisely of polyethylene terephthalate (PET), suitable for receiving liquid or semi-liquid products, such as in particular milk products, or similar products, generally referred to by the English abbreviation LDP for "Liquid Dairy Products", for distribution in the cold chain or at (aseptic) ambient temperature. The invention also relates to a preform and a mould for the manufacture of such a container. Background Art

[0002] As is known, plastic containers are obtained by blow moulding or stretch blow moulding of a preform in a mould having a mould cavity for the container.

[0003] Prior to blow molding the preform, whether or not it is stretched, the preform is heated until the material it is composed of reaches or exceeds the glass transition temperature. For example, in the case of a container made of polyethylene terephthalate, its glass transition temperature is approximately 70°C and can approach 80°C, depending on the material formulation.

[0004] Plastic containers generally include a body extending along a longitudinal axis and having a generally cylindrical shape rotating around the longitudinal axis, a bottom of the body closed at a first end of the body, a shoulder extending from a second end of the body as an extension of the body, and a neck located above the shoulder and having an opening. In addition, according to conventional designs, the bottom is strengthened by giving the bottom a hollow shape to define a dome intended to resist different stresses, and the bottom may additionally include radial reinforcements. These bottoms also define the placement plane of the container. That is, the container can be placed on its bottom in a stable manner.

[0005] Furthermore, in the packaging sector, it is well known that containers are in the form of vials, with a capacity less than or equal to 150 ml and intended to contain products according to the English abbreviation LDP for "Liquid Dairy Products", such as in particular milk products, distributed in the cold chain or at (aseptic) ambient temperature, the products being liquid or semi-liquid, such as drinkable yogurt with or without probiotics.

[0006] These containers are usually made of high-density polyethylene, usually called PEHD, or referred to by the English abbreviation "HDPE" (i.e. "High Density PolyEthylen"), or polystyrene. Containers made of HDPE or polystyrene are described in particular in documents JP2002363297, EP2012999 and US4595552.

[0007] Document JP2002363297 describes a bottle made of HDPE that is lightweight while maintaining the transparency, rigidity, impact resistance, and good dimensional stability required for food bottles, and does not change the taste of the contents after long-term storage. This plastic food bottle has a high-density polyethylene layer with a density greater than 0.950 g / cm3 and a molecular weight distribution defined by Mw (weight average molecular weight) / Mn (number average molecular weight) of 7.5. -14.5 , and the plastic bottle for food is formed to have less than 80% of the neck liner converted to a thickness of 0.5 mm.

[0008] Nevertheless, this type of HDPE container still has the disadvantage of being difficult to recycle in a closed-loop recycling, i.e., bottles made of HDPE can hardly be recycled into new HDPE bottles, and the cost of bottles made of recycled HDPE, called rHDPE, is particularly high due to the difficulty in recycling.

[0009] We also know document EP2012999, which describes a method for manufacturing plastic containers, in particular plastic bottles, according to which a preform made of polystyrene is heated and introduced into the cavity of a blow mould of a stretch-blow moulding system, the preform being expanded according to the cavity of the blow mould by a gas, usually air, injected under overpressure and stretched at the same time by a stretch rod. The method is characterized in that the preform made of polystyrene is introduced into the cavity, the preform having been manufactured to have an average wall thickness of about 1.6 to 3.4 mm, and the preform is subjected to a stretch blow moulding process at a blowing temperature of 125° C. to 140° C. The document also describes preforms made of special polystyrene that are particularly suitable for the method according to the invention.

[0010] In addition, document US4595552 describes an injection molding device for forming molded polystyrene articles, which includes a polymer (polystyrene) supply source, a mold cavity, a pipeline connecting the mold cavity and the supply source, an injection assembly for injecting molten polymer into the mold cavity, and a shut-off valve associated with the pipeline, the shut-off valve having an elongated central channel terminating in an outlet port, and a needle, which is positioned in an inclined relationship with the elongated central channel and can be selectively inserted into the port in a closed position, and the port and the elongated central channel can be retracted in an open position to provide unrestricted polymer flow.

[0011] Such an apparatus allows the temperature of the molten polystyrene to be reduced during injection molding without producing undesirable physical effects in the parison being formed. In fact, since polystyrene has lower strength properties than most plastics used for bottles, the wall thickness of polystyrene bottles must generally be greater than that of other plastics. Therefore, the parisons used to produce blow-molded polystyrene bottles also need to be relatively thick. However, from the point of view of production costs, the increased thickness of polystyrene bottles poses a significant problem. Since the injection molded parisons are thicker than most parisons used in plastic bottle molding, the cooling time of the polystyrene parisons must be longer to avoid crystallization or similar phenomena caused by rapid cooling, which negatively affects the strength and other characteristics of the finished parison. Since the cooling time of the parison is a key economic parameter, it is desirable to heat the polystyrene to the lowest possible temperature that still allows the polymer to flow correctly into the injection mold. However, if the temperature of the molten polystyrene in the injection mold becomes too low, certain undesirable features, such as weld lines, appear in the parison being formed and / or in the blow molded bottle subsequently formed.

[0012] Although the device described makes it possible to avoid these drawbacks, polystyrene bottles still have the drawback of being expensive to recycle. In fact, the recycling of polystyrene (PS) requires mechanical and chemical treatments, which makes the recycling of polystyrene expensive. Therefore, bottles made of recycled polystyrene are too expensive.

[0013] Therefore, it is necessary to make low-volume bottles, ie with a capacity less than or equal to 150 ml, obtained from recyclable and cheap materials such as polyethylene terephthalate (PET) at the lowest possible weight. At the same time, they have good blowability, allow high-speed manufacturing, and allow perfect control of material distribution. In fact, the search for saving materials and reducing polluting emissions is essential.

[0014] The present invention is particularly directed to meeting this need. Summary of the invention

[0015] One of the objects of the present invention is therefore to meet this need and to remedy the drawbacks of containers made of HDPE or polystyrene by proposing a container, a preform and a mould which have a simple and inexpensive design, require a small amount of material and have low-pressure blow mouldability allowing a high productivity while maintaining good rigidity.

[0016] For this purpose and according to the invention, a container is proposed, obtained by blow moulding or stretch blow moulding of a preform made of polyethylene terephthalate (PET), said container comprising: a body, a shoulder in the extension of said body at the upper end of said body; a neck in the extension of said shoulder, said neck being open and forming the mouth of the final container formed by said preform; and a bottom, said bottom being mounted on the lower end of said container and extending, said container being used to receive liquid or semi-solid products, such as in particular dairy products, or similar products, generally referred to by the English abbreviation LDP of "Liquid Dairy Products", distributed in the cold chain or at (aseptic) ambient temperature and having a capacity less than or equal to 150 ml, and being notable in that the height of said container from said mouth of said container to said bottom is less than or equal to 120 mm; and the height of said neck being less than 15 mm, the ratio defined as the ratio between the outer diameter of said body and the outer diameter below said neck being between 1.3 and 2.3.

[0017] These characteristics provide good blowability, including at low blowing pressures, a sufficiently rigid container, while having a particularly low weight, of about 5 g for a 150 ml container. Thus, in addition to the fact that PET is recyclable in closed-loop recycling, the container according to the invention allows the container to be manufactured at very low costs, thanks to its good blowability at low pressures, which allows a high manufacturing rate, and the small amount of material (PET) used for its manufacture.

[0018] Preferably, the ratio between the area of ​​the container under the neck expressed in square centimeters and the weight of the container expressed in grams is between 18 and 45.

[0019] Furthermore, the outer diameter below the neck is preferably less than or equal to 31 mm and the maximum outer diameter of the body is less than or equal to 54 mm.

[0020] Advantageously, the body has, over all or part of its height, a superposition of annular reinforcements which improve the rigidity of the container.

[0021] Furthermore, the bottom comprises a peripheral seat and a concave central dome in the form of a substantially spherical cap having a concave shape towards the outside of the container, the central dome being rigid or semi-rigid.

[0022] Incidentally, the central dome may include one or more reinforcements in order to increase the rigidity of the base.

[0023] In this regard, the central dome includes a plurality of radial reinforcements extending substantially from the center of the central dome to the peripheral seat.

[0024] Incidentally, the body comprises, between a central portion of the body and the neck, an annular groove forming a constriction, in particular improving the grip of the container.

[0025] Another object of the invention relates to a preform for forming a container according to the invention by blow moulding or stretch blow moulding, said preform being made of polyethylene terephthalate (PET) and comprising a neck, a body and a base, said body being rotationally symmetrical about a central axis C, having a cylindrical portion of revolution, formed by a wall having an outer skin and an inner skin, said base being located at one end of said body while closing said end, said neck extending in said body extension at the opposite end of said body, said neck being open and forming the mouth of the final container formed by said preform. The significant characteristics of said preform are that its height from said mouth to said base is less than or equal to 50 mm, that the outer diameter of said body is less than or equal to 25 mm and that the thickness of the wall of said body, that is, the thickness between said inner skin and said outer skin, is between 1.2 mm and 2.0 mm.

[0026] Preferably, the base of the preform has a substantially hemispherical shape and an outer radius of curvature of between 6 and 13 millimeters.

[0027] Incidentally, the preform comprises at least one additive which imparts to the polyethylene terephthalate the property of at least partially filtering the visible spectrum of light.

[0028] A final object of the invention relates to a mould for manufacturing containers made of preforms according to the invention made of polyethylene terephthalate (PET) by blow moulding or stretch blow moulding, the mould comprising at least one mould bottom capable of being movably mounted in a side wall defining a cavity having a portion of the container, the side wall comprising two mould halves, each of which defines a half-cavity of the body of the container, and the two mould halves being mounted to rotate relative to each other between an open position and a closed position, in which the mould halves are angularly spaced from each other and the mould bottom is lowered relative to the mould halves to allow the introduction of the blank and the ejection of the formed container, and in which the mould halves abut against each other and clamp the mould bottom between them, thereby forming the cavity and defining the entire cavity of the container to be formed, characterised in that the mould half-cavities of the side wall and / or the mould bottom are shaped for producing a container according to the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Other advantages and features will become more apparent from the following description of several implementation variants of a container, a preform and a mold for producing said container according to the invention, given by way of non-limiting examples, with reference to the accompanying drawings, in which:

[0030] [ Figure 1 ] is a perspective view of a container according to the present invention;

[0031] [ Figure 2 ] is a side view of the container according to the present invention shown in [Figure 1];

[0032] [ Figure 3 ] is a bottom view of the container according to the present invention, that is to say a view showing the bottom of the container;

[0033] [ Figure 4 ] is a side view of a preform according to the invention for use in manufacturing a container according to the invention;

[0034] [ Figure 5 ]yes[ Figure 4 ] is a view of the preform shown;

[0035] [ Figure 6 ] is a transparent partial perspective view of a mold for manufacturing a container according to the invention from a preform according to the invention. DETAILED DESCRIPTION

[0036] In the remainder of the description of the container according to the invention, the same reference numerals refer to the same elements. The different views are not necessarily drawn to scale.

[0037] refer to Figures 1 to 3, shows a container 1 , in this case a bottle, which is produced by stretch blow moulding from a preform made of a thermoplastic material, such as PET (polyethylene terephthalate), which will be described in detail below.

[0038] Said container 1 comprises, at the upper end, a threaded neck 2 provided with a mouth 3. In the extension of the neck 2, the container 1 comprises, in its upper part, a shoulder 4 which widens gradually in a direction opposite to the neck 2, this shoulder 4 being extended by a side wall or body 5 having a substantially cylindrical shape of revolution about a main axis X of the container 1.

[0039] It goes without saying that the main body 5 can have different shapes, such as a square cross section with edges such as quarter-circular shapes, without departing from the scope of the present invention.

[0040] The container 1 further comprises a bottom 6 extending to the lower end of the container 1. Figure 3 ], the bottom 6 comprises a base 7 in the form of a thin annular flange, which extends axially substantially in the extension direction of the body 5. The base 7 terminates in a continuous flat annular surface, which forms the lower end of the container 1 and defines a placement plane 8 perpendicular to the axis of the container 1, through which the container can be stably placed on a flat surface. The placement plane 8 is connected outwardly to the outer side 9 of the base 7 (which extends in the extension of the body 5) by a fillet 10 with a small radius of curvature (i.e., in the order of millimeters).

[0041] Towards the interior of the container 1, the base 7 comprises an annular side wall surface 11 which extends axially towards the interior of the container 1 in the extension of the resting plane 8. The resting plane 8 is connected to the side wall surface 11 inwardly via a fillet 12 which preferably has a small radius of curvature.

[0042] The bottom 6 also comprises a concave central dome 13 in the form of a substantially spherical cap, with a concave shape facing the outside of the container and extending in the extension of the side wall face 11 (which forms the junction between the resting plane 8 and the dome 13) up to a central zone 14 forming a pin 15, which protrudes axially towards the inside of the container 1, said central dome 13 being rigid or semi-rigid. As shown in the figures, the bottom 6 is also provided with a series of reinforcements 16 extending from the central zone 14 substantially to the resting plane 8. Preferably, the reinforcements 16 do not extend beyond the resting plane 8, that is to say, they do not extend onto the external lateral surface 9. In this particular embodiment, there are five of said reinforcements 16; however, this number is provided as an example and may be different.

[0043] Furthermore, it goes without saying that the reinforcement element can extend beyond the support plane 8 by projecting onto the outer side 9 , without departing from the scope of the present invention.

[0044] Furthermore, the body 5 has, over all or part of its height, the superposition of an annular reinforcement 17 , making it possible to increase the rigidity of said body 5 .

[0045] Furthermore, the body 5 comprises an annular groove 18 between the central portion of the body 5 and the neck 2 , forming a constriction which notably provides a better grip of the container and improves the rigidity of the body 5 of the container 1 .

[0046] An essential feature of the container 1 according to the invention is that the height of said container 1 from the mouth 3 to the bottom 6 of the container 1 is less than or equal to 120 mm and that the ratio defined as the ratio between the external diameter of the body 5 and the external diameter under the neck 2 is between 1.3 and 2.3, the height of the neck being less than 15 mm. These features provide good blowability even at low blow molding pressures and ultimately a sufficiently rigid container is obtained, while being particularly light, less than or equal to 5 g, depending on the container capacity (less than or equal to 150 ml). Low blow molding pressures are blow molding pressures between 10 and 18 bar. Thus, in addition to the closed-loop recycling of PET (polyethylene terephthalate), the container manufactured according to the invention, due to the excellent adaptation between the preform and the packaging, whether virgin PET or recycled PET (called rPET) is used, achieves optimal lightness at very low blow molding pressures and maximum production speed, thus making the container very cheap to manufacture.

[0047] In addition, the ratio between the area of ​​the container under the neck expressed in square centimeters and the weight of the container expressed in grams is between 18 and 45, the outer diameter under the neck is preferably less than or equal to 31 mm, and the maximum outer diameter of the body is less than or equal to 54 mm.

[0048] In order to manufacture the container according to the invention, reference is made to Figure 4 and Figure 5 The preform 19 for forming a container according to the invention by blow moulding or stretch blow moulding is obtained from polyethylene terephthalate (PET) and comprises in a usual manner a neck 20, a body 21 and a base 22, the body 21 being rotationally symmetrical about a central axis C, having a cylindrical portion of revolution and formed by a wall having an outer skin 23 and an inner skin 24, the base 22 being located at one end of the body 21 while closing this end, and the neck 20 extending in the extension of the body 21 at the end opposite to the base 22, the neck 20 being open and forming the mouth 3 of the final container 1 formed from the preform 19.

[0049] The height of the preform from the bottle mouth 3 to the base 22 is less than or equal to 50 mm, the outer diameter of the body 21 is less than or equal to 25 mm, and the thickness of the wall of the body 21, that is, the thickness between the inner skin 24 and the outer skin 23, is between 1.2 mm and 2.0 mm.

[0050] Preferably, the base of the preform has a substantially hemispherical shape and an outer radius of curvature of between 6 mm and 13 mm.

[0051] Furthermore, the preform comprises at least one additive which imparts to the polyethylene terephthalate the property of at least partially filtering the visible spectrum of light.

[0052] According to a known example, for dairy products, the preform 19 made of PET resin is added with titanium dioxide (TiO2). Titanium dioxide provides white color and, in certain proportions known to those skilled in the art, provides a light barrier function in visible light and can prevent the degradation of riboflavin (vitamin B2).

[0053] In addition, refer to [ Figure 6 ], in order to manufacture a container by blow moulding or stretch blow moulding of a moulded part 19 made of polyethylene terephthalate (PET) as described above, a mould 30 is used. The mould comprises at least one mould base 31 which can be movably mounted in a side wall 32 which defines a cavity 33 of a mould cavity having a part of the container 1, said side wall 32 comprising two half-moulds 34a, 34b, each half-mould defining a half-cavity 35a, 35b of the body 5 of the container 1, and the two half-moulds are mounted to rotate relative to each other between an open position and a closed position, in which the half-moulds 34a, 34b are angularly spaced from each other and the mould base 31 is lowered relative to the half-moulds 34a, 34b to allow the introduction of the blank and the ejection of the formed container 1, and in which the half-moulds 34a, 34b abut against each other and clamp the mould base 31 between them, thereby forming the cavity 33 and defining the entire mould cavity of the container 1 to be formed. The mold half-cavities 35 a , 35 b of the side wall 32 and / or the mold base 31 are shaped for producing the container 1 according to the invention.

[0054] Finally, it is quite obvious that the examples just given are only specific illustrations and are in no way limiting to the field of application of the invention.

Claims

1. A container (1) obtained by blow molding or stretch blow molding of a preform (19) made of polyethylene terephthalate (PET), the container comprising: A body (5); a shoulder (4) in extension of the body (5) at the upper end of the body; a neck (2) in extension of the shoulder (4), the neck (2) being open and forming the mouth (3) of a final container (1) formed by the preform (19); and a bottom (6) mounted on the lower end of the container (1) and extending therefrom, the container (1) being used to receive liquid or semi-solid products, such as in particular dairy products, or similar products, generally referred to as "Liquid Dairy Products" in English by the abbreviation LDP, distributed in a cold chain or at (aseptic) room temperature and having a capacity of less than or equal to 150 ml, characterized in that the height of the container (1) from the mouth (3) of the container to the bottom (6) is less than or equal to 120 mm; and the height of the neck (2) is less than 15 mm, defined as the ratio between the outer diameter of the body (5) and the outer diameter below the neck (2) being between 1.3 and 2.

3.

2. The container (1) according to claim 1, characterized in that The ratio between the area of ​​the container (1) below the neck (2) expressed in square centimeters and the weight of the container (1) expressed in grams is between 18 and 45.

3. The container (1) according to claim 1 or 2, characterized in that: The outer diameter below the neck (2) is less than or equal to 31 mm.

4. The container (1) according to any one of claims 1 to 3, characterized in that The maximum outer diameter of the main body (5) is less than or equal to 54 mm.

5. The container (1) according to any one of claims 1 to 4, characterized in that The body (5) has a superposition of annular reinforcements (17) over all or part of its height.

6. The container (1) according to any one of claims 1 to 5, characterized in that The bottom (6) comprises a peripheral seat (8) and a concave central dome (13) in the form of a substantially spherical cap having a concave shape towards the outside of the container.

7. The container (1) according to claim 6, characterized in that The central dome (13) is rigid or semi-rigid.

8. The container (1) according to claim 7, characterized in that The central dome (13) includes one or more reinforcement members (16).

9. The container (1) according to claim 8, characterized in that The central dome (13) comprises a plurality of radial reinforcements (16) extending substantially from the centre of the central dome (13) to the peripheral seat (8).

10. The container (1) according to any one of claims 1 to 9, characterized in that The body (5) comprises an annular groove (18) forming a constriction between a central portion of the body (5) and the neck (2).

11. A preform (19) intended for forming a container (1) according to any one of claims 1 to 10 by blow moulding or stretch blow moulding, the preform (19) being made of polyethylene terephthalate (PET) and comprising a neck (20), a body (21) and a base (22), the body (21) being rotationally symmetrical about a central axis C, having a cylindrical portion of revolution, formed by a wall having an outer skin (23) and an inner skin (24), the base (22) being located at one end of the body (21) while closing the end, the neck (20) extending in an extension of the body (21) at the opposite end of the body (21), the neck (20) being open and forming the mouth (3) of the final container (1) formed by the preform (19), characterized in that The height of the preform (19) from the bottle mouth (3) to the base (22) is less than or equal to 50 mm, the outer diameter of the body (21) is less than or equal to 25 mm, and the thickness of the wall of the body (21), that is, the thickness between the inner skin (24) and the outer skin (23), is between 1.2 mm and 2.0 mm.

12. The preform (19) according to claim 11, characterized in that The base (22) has a substantially hemispherical shape.

13. The preform (19) according to claim 12, characterized in that The base (22) has an outer radius of curvature between 6 mm and 13 mm.

14. The preform (19) according to any one of claims 11 to 13, characterized in that The preform comprises at least one additive which imparts to the polyethylene terephthalate at least partially filtering properties of the visible light spectrum.

15. A mould (30) for producing a container (1) by blow moulding or stretch blow moulding of a preform (19) according to any one of claims 11 to 14 made of polyethylene terephthalate (PET), the mould (30) comprising at least one mould base (31) which can be movably mounted in a side wall (32), the side wall defining a cavity (33) with a mould cavity of a part of the container (1), the side wall comprising two half-moulds (34a, 34b), each of the half-moulds defining a half-mould cavity (35a) of the body (5) of the container (1) , 35b), and the two half-molds are mounted to rotate relative to each other between an open position and a closed position, in which the half-molds (34a, 34b) are angularly spaced from each other and the mold base (31) is lowered relative to the half-molds (34a, 34b) to allow the introduction of the blank and the discharge of the formed container (1), and in the closed position, the half-molds (34a, 34b) abut against each other and clamp the mold base (31) between them, thereby forming the cavity (33) and defining the entire mold cavity of the container (1) to be formed, characterized in that The side wall half-cavities (35a, 35b) and / or the mold base (31) are shaped for producing a container (1) according to any one of claims 1 to 10.

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