PET and / or rPET containers for liquid or semi-liquid products, commonly known as LDPs etc.

Abstract

The present invention relates to a container (1) obtained by blow molding or stretch blow molding from a preform (19) made of polyethylene terephthalate (PET), the container comprising a body (5), a shoulder (4) extending from the body (5) at its upper end, a neck (2) extending from the shoulder (4), the neck (2) being open and forming a rim (3) of the final container (1) formed from the preform (19), and a bottom (6) extending to the lower end of the container (1), the container (1) being suitable for use in cold chains. The present invention relates to a container (1) intended to contain liquid or semi-liquid products, commonly known as liquid dairy products (LDPs), in particular dairy products, dispensed through a container or at ambient temperature (aseptic) and having a volume of 150 ml or less; characterized in that the height of the container (1) from the rim (3) to the bottom (6) of the container is 120 mm or less, the ratio defined as the ratio of the outer diameter of the body (5) to the outer diameter below the neck (2) is between 1.3 and 2.3, and the height of the neck (2) is less than 15 mm. The present invention further relates to a preform for producing the container according to the invention and, finally, to a mold for producing such a container.

Description

[Technical Field]

[0001] The field of the invention is that of designing and manufacturing containers from preforms made of plastic material. The invention relates more particularly to the design of containers made of plastic material, more particularly polyethylene terephthalate (PET), adapted to contain liquid or semi-liquid products, such as dairy products in particular, commonly referred to as liquid dairy products (LDP), and distributed in the cold chain or at ambient temperature (aseptic). The invention also relates to preforms and molds for manufacturing such containers. [Background technology]

[0002] It is well known that containers made of plastic material are obtained by blow molding or stretch blow molding a preform in a mold with the shape of the container.

[0003] Before being blown, with or without stretching, the preform is heated until its constituent material reaches or exceeds its glass transition temperature. For example, if the container is made of polyethylene terephthalate, the glass transition temperature is about 70°C and can approach 80°C depending on the material formulation.

[0004] A plastic container typically comprises a body extending along a longitudinal axis and substantially in the shape of a cylinder of revolution about the longitudinal axis, a base closing the body at its first end, a shoulder extending from its second end to the body, and a neck covering the shoulder and having an opening. Furthermore, according to conventional designs, the base is reinforced by a hollow shape defining an arch intended to withstand different stresses, and the base may further comprise a radial reinforcement. These bases also define a standing plane for the container, meaning that the container can be stably placed on the base.

[0005] Further well known in the field of packaging are containers in the form of small bottles with a volume of 150 ml or less intended to contain liquid dairy products (LDP), in particular liquid or semi-liquid dairy products such as drinking yogurts that are distributed in the cold chain or at ambient temperature (aseptic) and that may or may not contain probiotics.

[0006] These containers are usually made either from high density polyethylene (HDPE) or polystyrene. Containers made from HDPE or polystyrene are described in particular in the documents JP 2002-363297, EP 2012999 and US 4,595,552.

[0007] The document JP 2002-363297 describes a bottle made from HDPE, which is lightweight, rigid, impact resistant, has good dimensional stability and does not affect the taste of the contents after long-term storage, while still retaining the transparency required for a food bottle. This food plastic bottle has a density of 0.950 g.cm -3 The molecular weight distribution, defined as Mw (weight average molecular weight) / Mn (number average molecular weight), is 7.5. -14.5 and formed so that at least 80% of the bottle web is converted to a thickness of 0.5 mm.

[0008] However, this type of HDPE container has the disadvantage that it is difficult to recycle in a closed cycle, i.e., it is difficult for HDPE bottles to be recycled into new HDPE bottles, and the cost of recycled HDPE bottles (called rHDPE) is particularly high due to the difficulty of recycling.

[0009] EP 2012999 also describes a method for producing plastic containers, particularly plastic bottles, in which a preform made of polystyrene is heated and inserted into the mold cavity of a blow mold of a stretch-blow molding system. The preform is expanded along the cavity of the blow mold by an excess pressure, usually air, and simultaneously stretched by a stretch rod. The blown container is then demolded. This method is characterized in that a polystyrene preform is inserted into the mold cavity, the preform is produced with an average wall thickness of approximately 1.6 to 3.4 mm, and the preform is subjected to a stretch-blow molding process carried out at a blowing temperature of 125°C to 140°C. Preforms made of special polystyrenes are also described that are particularly suitable for the method according to the invention.

[0010] Furthermore, U.S. Pat. No. 4,595,552 describes an injection molding apparatus for forming molded polystyrene articles, comprising a source for supplying polymer (polystyrene), a mold cavity, a pipe connecting the mold cavity and the source, an injection assembly for injecting molten polymer into the mold cavity, an elongated central passage associated with the pipe and terminating in an exit orifice, and a stop valve having a needle disposed obliquely relative to the elongated central passage, which may be selectively inserted into the orifice in a closed position and retractable from the orifice and the elongated central passage to provide unrestricted flow of polymer in an open position.

[0011] Such equipment allows the temperature of molten polystyrene to be reduced during injection molding without causing undesirable physical effects on the resulting parison. Specifically, because polystyrene has lower strength properties than most plastics used in bottles, the wall thickness of polystyrene bottles generally must be thicker than that of other plastics. Therefore, parisons used to produce blow-molded polystyrene bottles must also be relatively thick. However, increasing the thickness of polystyrene bottles poses significant problems in terms of production costs. Because injection-molded parisons are thicker than most parisons used to form plastic bottles, the cooling time of polystyrene parisons must be long to avoid crystallization or similar phenomena caused by rapid cooling, which can adversely affect the strength and other properties of the finished parison. Because parison cooling time is an important economic parameter, it is desirable to heat the polystyrene to the lowest possible temperature while still allowing for accurate flow of the polymer into the injection mold. However, if the temperature of the molten polystyrene in the injection mold becomes too low, certain undesirable characteristics, such as weld lines, can appear in the parison being formed and / or the subsequently formed blow-molded bottle.

[0012] Although the device allows these drawbacks to be avoided, polystyrene bottles have the drawback that they are expensive to recycle. Specifically, recycling polystyrene (PS) requires mechanical and chemical treatments, making it expensive. Therefore, producing bottles from recycled polystyrene is very expensive.

[0013] Therefore, there is a need to produce small-volume bottles, i.e., bottles with a capacity of 150 ml or less, made from recyclable and inexpensive materials such as polyethylene terephthalate (PET), with the lowest possible weight while having good blow moldability for high-speed production with complete control over material distribution. Specifically, the pursuit of material conservation and reduced polluting emissions are key factors.

[0014] The object of the present invention is to meet this need among others. [Prior art documents] [Patent documents]

[0015] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-363297 [Patent Document 2] European Patent No. 2012999 [Patent Document 3] U.S. Patent No. 4,595,552 Summary of the Invention [Problem to be solved by the invention]

[0016] One of the aims of the present invention is therefore to meet this need and to remedy the shortcomings of containers obtained from HDPE or polystyrene by proposing containers, preforms and moulds of simple and inexpensive design, which require a small amount of material and have low-pressure blow mouldability, allowing high production rates whilst maintaining good rigidity. [Means for solving the problem]

[0017] To this end, the invention proposes a container obtained by blow molding or stretch-blow molding from a preform made of polyethylene terephthalate (PET), comprising a body, a shoulder at its upper end that is a continuation of the body, a neck that is a continuation of the shoulder and is open, forming the rim of the final container made from the preform, and a base that extends to the lower end of the container, the container intended to contain aseptic, liquid or semi-liquid products, generally called liquid dairy products (LDP), in particular dairy products, that are distributed in the cold chain or at ambient temperature (aseptically) and have a volume of 150 ml or less, and it is noteworthy that the height from the rim to the bottom of the container is 120 mm or less, and the ratio of the outer diameter of the body to the outer diameter below the neck is between 1.3 and 2.3, and the height of the neck is less than 15 mm.

[0018] These characteristics provide good blow moldability, including low blow pressure and a particularly low weight, on the order of 5 grams for a 150 ml container, yet still being sufficiently rigid. Thus, in addition to the fact that PET is recyclable in a closed circuit, the container according to the invention allows for the production of containers at very low cost due to its good low-pressure blow moldability, which allows for fast production speeds and requires only a small amount of material (PET) for its production.

[0019] Preferably, cm relative to the weight of said container expressed in grams 2 The ratio of the area under the neck of the container, expressed as:

[0020] It is also preferable that the outer diameter below the neck is 31 mm or less, and the maximum outer diameter of the main body is 54 mm or less.

[0021] Advantageously, the body has, over all or part of its height, a superposition of annular stiffeners, said stiffeners improving the rigidity of said container.

[0022] Furthermore, the base comprises a peripheral seat and a concave central dome in the form of a substantially spherical cap, the concave surface of which faces the outside of the container, said central dome being rigid or semi-rigid.

[0023] Additionally, the central dome may include one or more stiffeners to increase the rigidity of the base.

[0024] In this regard, the central dome may include a plurality of radial stiffeners extending substantially from the center of the central dome to the peripheral seat.

[0025] Furthermore, the body comprises an annular groove between the central part of the body and the neck, which forms a constriction that in particular improves grip of the container.

[0026] Another object of the invention relates to a preform intended to form a container by blow moulding or stretch blow moulding according to the invention, said preform consisting of polyethylene terephthalate (PET) and comprising a neck, a body and a bottom, said body exhibiting rotational symmetry about a central axis C, with a portion which is a cylinder of revolution, formed by a wall having an outer shell and an inner shell, said bottom being closed at one of the ends of the body and said neck being continuous with and extending from the body at the opposite end, said neck being open and forming the rim of the final container formed from said preform, said preform being characterized in that it has a height from rim to bottom of not more than 50 mm, an outer diameter of the body of not more than 25 mm and a wall thickness of the body, i.e. the thickness between the inner and outer shells, of between 1.2 and 2.0 mm.

[0027] Preferably, the bottom of the preform has a substantially hemispherical shape and an outer radius of curvature between 6 and 13 mm.

[0028] Additionally, the preform includes at least one additive that imparts to the polyethylene terephthalate the property of at least partially blocking the visible spectrum of light.

[0029] A final object of the present invention relates to a mold for producing containers by blow molding or stretch-blow molding a preform made of polyethylene terephthalate (PET) according to the invention, said mold comprising at least one mold bottom movably mountable within a side wall defining a cavity having an embossment of a portion of the container, said side walls comprising two mold halves, each defining a half-embossment of the body of the container, the half-molds being angularly spaced apart from each other and rotatably mounted relative to each other between a position called the open position, in which the mold bottom is lowered relative to the half-molds to allow the insertion of the blank and the ejection of the formed container, and a position called the closed position, the half-molds being in close contact with each other and enclosing the mold bottom between them to form the cavity and define the complete embossment of the container to be formed; said mold is notable in that the half-embossments of the side walls and / or the mold bottom are shaped to produce a container according to the invention.

[0030] Further advantages and features will become more apparent from the following description of some embodiment variants, given as non-limiting examples, of the container, the preform and the mold for producing said container according to the invention, with reference to the attached drawings, in which: [Brief explanation of the drawings]

[0031] [Figure 1] 1 is a perspective view of a container according to the present invention; [Figure 2] 2 is a side view of the container according to the present invention shown in FIG. 1. [Figure 3] 1 shows a bottom view of a container according to the invention, i.e., a view of the bottom of the container. [Figure 4] 1 is a side view of a preform according to the invention for manufacturing a container according to the invention; [Figure 5] FIG. 5 is an elevational view of the preform shown in FIG. [Figure 6] 1 is a transparent partial perspective view of a mold for producing a container according to the invention from a preform according to the invention; DETAILED DESCRIPTION OF THE INVENTION

[0032] In the remainder of the description of the container according to the invention, the same reference numerals refer to the same elements. The different figures are not necessarily drawn to scale.

[0033] 1 to 3 show a container 1, in this embodiment a bottle manufactured by stretch blow molding from a preform made of a thermoplastic material such as polyethylene terephthalate (PET), which will be described in detail later.

[0034] The container 1 comprises, at its upper end, a threaded neck 2 provided with a rim 3. Adjoining the neck 2, the container 1 comprises, at its upper part, a shoulder 4 flaring away from the neck 2 and extending from a side wall or body 5 having the general shape of a cylinder of revolution centered on the main axis X of the container 1.

[0035] It goes without saying that the body 5 can have different shapes, for example a square cross section with quarter rounded edges, without departing from the scope of the invention.

[0036] The container 1 further comprises a bottom 6 extending to the lower end of the container 1. The bottom 6 comprises, with reference to Figure 3, a seat 7 in the form of a thin annular bead extending substantially axially in a continuous manner into the body 5. The seat 7 forms the lower end of the container 1 and terminates in a continuous planar and annular surface that defines an upstanding plane 8 perpendicular to the axis of the container 1, allowing the latter to rest stably on a flat surface. The upstanding plane 8 is connected outwardly to an outer side surface 9 of the seat 7 (which extends in a continuous manner into the body 5) by a fillet 10 having a small radius of curvature, i.e. a radius of curvature of about 1 millimeter.

[0037] Towards the inside of the container 1, the seat 7 comprises an annular flange 11 which is continuous with the upstanding plane 8 and extends axially towards the inside of the container 1. The upstanding plane 8 is connected to the inside of the flange 11 by a fillet 12, preferably of small radius of curvature.

[0038] The bottom 6 further comprises a concave central dome 13 in the form of a substantially spherical cap with a concave surface facing the outside of the container, said central dome extending continuously from the flange 11 (forming the junction between the standing plane 8 and the arch 13) to a central zone 14 forming a pin 15 projecting axially towards the inside of the container 1, said central dome 13 being rigid or semi-rigid. As shown in the drawings, the bottom 6 is further provided with a series of stiffeners 16 extending from the central zone 14 substantially to the standing plane 8. Preferably, the stiffeners 16 do not extend beyond the standing plane 8, i.e., do not overhang the outer side surface 9. In this particular exemplary embodiment, there are five of said stiffeners 16; however, this number is provided by way of example and may vary.

[0039] Furthermore, it goes without saying that said stiffeners can extend beyond the standing plane 8 by overhanging the outer side 9 without departing from the scope of the invention.

[0040] Furthermore, the body 5 has, over all or part of its height, a superposition of annular stiffeners 17 making it possible to increase the rigidity of said body 5 .

[0041] Furthermore, the body 5 comprises an annular groove 18 which forms a constriction between the central part of the body 5 and the neck 2 which in particular provides a better grip on the container and improves the rigidity of the body 5 of the container 1 .

[0042] According to essential features of the container 1 of the present invention, the height of the container 1 from the rim 3 to the bottom 6 of the container 1 is 120 mm or less, the ratio, defined as the ratio of the outer diameter of the body 5 to the outer diameter below the neck 2, is between 1.3 and 2.3, and the height of the neck is less than 15 mm. These features provide good blow moldability even at low blow pressures, resulting in a container with a particularly low weight (less than 5 grams for a container volume of 150 ml or less), while still being sufficiently rigid. Low blow pressures are understood to mean blow pressures between 10 and 18 bar. Thus, in addition to the fact that PET is recyclable in a closed circuit, the container of the present invention, whether made from virgin PET or recycled PET (referred to as rPET), allows for optimal weight reduction at very low blow pressures, due to the excellent compatibility of preforms, packaging, and maximum production rates, making it possible to produce the container at very low cost.

[0043] Furthermore, the weight of the container in grams is expressed as cm 2 The ratio of the area of ​​the container below the neck, expressed as: is between 18 and 45, the outer diameter below the neck is preferably 31 mm or less, and the maximum outer diameter of the body is 54 mm or less.

[0044] 4 and 5, for producing a container according to the present invention, a preform 19 intended to form a container by blow molding or stretch blow molding according to the present invention is obtained from polyethylene terephthalate (PET) and typically comprises a neck 20, a body 21 and a bottom 22, said body 21 exhibiting rotational symmetry about a central axis C, having a portion which is a cylinder of revolution, and formed by a wall having an outer shell 23 and an inner shell 24, the bottom 22 being located at one end of the body 21 and closed, and the neck 20 extending continuously with the body 21 at the end opposite the bottom 22, said neck 20 being open and forming the rim 3 of the final container 1 formed from said preform 19.

[0045] The preform has a height from the rim 3 to the bottom 22 of 50 mm or less, an outer diameter of the body 21 of 25 mm or less, and a wall thickness of the body 21, i.e., the thickness between the inner shell 24 and the outer shell 23, of between 1.2 and 2.0 mm.

[0046] Preferably, the bottom of the preform has a substantially hemispherical shape and an outer radius of curvature between 6 and 13 mm.

[0047] Additionally, the preform includes at least one additive that imparts to the polyethylene terephthalate the property of at least partially blocking the visible spectrum of light.

[0048] According to a well-known example, in the case of dairy products, the preforms 19 made of PET resin are supplemented with titanium dioxide (TiO2), which provides a white color and, in certain proportions known to those skilled in the art, provides a barrier function against light in the visible spectrum and prevents the degradation of riboflavin (vitamin B2).

[0049] Further, referring to FIG. 6, to manufacture a container by blow molding or stretch-blow molding a polyethylene terephthalate (PET) preform 19 as described above, a mold 30 is used, which includes at least a mold bottom 31 movably mountable within a side wall 32 defining a cavity 33 by embossing a portion of the container 1, said side wall 32 including mold halves 34a, 34b each defining a half-embossment 35a, 35b of the body 5 of the container 1, and the mold halves 34a, 34b are rotatable relative to one another. The mold halves 34a, 34b are rotatably mounted and operable between two positions, referred to as the open position, in which the mold halves 34a, 34b are angularly spaced apart from one another and the mold bottom 31 is lowered relative to the mold halves 34a, 34b to allow insertion of the preform 19 and ejection of the formed container 1, and a position referred to as the closed position, in which the mold halves 34a, 34b are brought into close contact with one another and enclose the mold bottom 31 therebetween, thereby forming a cavity 33 and defining a complete embossment of the formed container 1. The embossments 35a, 35b of the sidewall 32 and / or the mold bottom 31 are shaped to produce the container 1 according to the invention.

[0050] Finally, it is very clear that the examples just given are only specific illustrations that in no way limit the field of application of the invention.

Claims

1. A container (1) obtained by blow molding or stretch blow molding from a polyethylene terephthalate (PET) preform (19), comprising a body (5), a shoulder (4) at the upper end of the body (5) that is continuous with the body (5), a neck (2) that is continuous with the shoulder (4), the neck (2) being open and forming a rim (3) of the final container (1) formed from the preform (19), and a bottom (6) that extends to the lower end of the container (1), wherein the container (1) is Container (1) intended to contain liquid or semi-liquid products, generally referred to as liquid dairy products (LDP), such as dairy products, to be dispensed at cold chain or ambient temperature (aseptic) and having a volume of 150 ml or less, characterized in that the height from the rim (3) of the container (1) to the bottom (6) of the container is 120 mm or less, the ratio defined as the ratio of the outer diameter of the body (5) to the outer diameter below the neck (2) is between 1.3 and 2.3, and the height of the neck (2) is less than 15 mm.

2. cm relative to the weight of the container (1) expressed in grams ２ Container (1) according to claim 1, characterized in that the ratio of the area of ​​the container (1) under the neck (2) expressed as:

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

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

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

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

8. Container (1) according to claim 7, characterized in that the central dome (13) is provided with one or more stiffeners (16).

9. 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 center of the central dome (13) to the peripheral seat (8).

10. 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 the central part of the body (5) and the neck (2).

11. A preform (19) intended to form a container (1) by blow molding or stretch blow molding according to any one of claims 1 to 10, said preform (19) being made of polyethylene terephthalate (PET) and comprising a neck (20), a body (21) and a bottom (22), said body (21) exhibiting rotational symmetry about a central axis C, having a portion which is a cylinder of revolution, formed by a wall having an outer shell (23) and an inner shell (24), said bottom (22) being located at one of the ends of the body (21). a neck (20) extending continuously into the body (21) at an opposite end of the body (21), the neck (20) being open and forming the rim (3) of the final container (1) formed from the preform (19), the preform (19) being characterized in that the height from the rim (3) to the bottom (22) is 50 mm or less, the outer diameter of the body (21) is 25 mm or less, and the wall thickness of the body (21), i.e., the thickness between the inner shell (24) and the outer shell (23), is between 1.2 and 2.0 mm.

12. 12. Preform (19) according to claim 11, characterized in that the bottom (22) has a substantially hemispherical shape.

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

14. Preform (19) according to any one of claims 11 to 13, characterized in that it comprises at least one additive that gives polyethylene terephthalate the property of at least partially blocking the visible spectrum of light.

15. A mold (30) for producing a container (1) by blow molding or stretch-blow molding a preform (19) made of polyethylene terephthalate (PET) according to any one of claims 11 to 14, said mold (30) comprising at least one mold bottom (31) movably mountable within a side wall (32) defining a cavity (33) with an embossment of a portion of the container (1), said side wall comprising mold halves (34a, 34b) each defining a half embossment (35a, 35b) of the body (5) of the container (1), said mold halves 34a, 34b being rotatably mounted relative to one another and operable between an open position and a closed position, a position called the open position, in which the mold halves (34a, 34b) are angularly spaced apart from one another and the mold bottom (31) is lowered relative to the mold halves (34a, 34b) to allow the insertion of the blank and the ejection of the formed container (1); and a position called the closed position, in which the mold halves (34a, 34b) are in close contact with one another to form a cavity (33) and enclose the mold bottom (31) therebetween so as to define the complete embossment of the container (1) to be formed, the side walls and / or the embossments (35a, 35b) of the mold bottom (31) being shaped to produce a container (1) according to any one of claims 1 to 10.

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