Pet and / or rpet container for liquid or semi-liquid products commonly known as ldp or the like

Abstract

The present invention relates to a container (1) obtained by blow moulding or stretch blow moulding from a preform (19) made of polyethylene terephthalate (PET), which container comprises a body (5), a shoulder (4) extending from said body (5) at an upper end thereof, a neck (2) extending from the shoulder (4), said neck (2) being open and forming a rim (3) of the final container (1) formed from said preform (19), and a bottom (6) which extends at a lower end of the container (1), said container (1) being intended to receive a liquid or semi-liquid product commonly known as liquid dairy products (LDP), such as milk products in particular, or the like, distributed through a cold chain or at ambient temperature (aseptic), and having a capacity of less than or equal to 150 ml; said container (1) is characterised in that the height of the container (1) from the rim (3) to the bottom (6) of the container is less than or equal to 120 mm and in that the ratio defined as that between the outside diameter of the body (5) and the outside diameter beneath the neck (2) is between 1.3 and 2.3, the height of the neck (2) being less than 15 mm. The invention further relates to a preform for the manufacture of a container according to the invention and finally relates to a mould for the production of such containers.

Description

Description Title of the invention: PET and / or rPET container for liquid or semi-liquid products commonly called LDP or similar Technical field

[0001] The field of the invention is that of the design and manufacture of containers from plastic preforms. The invention relates more particularly to a design of plastic containers, more precisely polyethylene terephthalate (PET) suitable for receiving a liquid or semi-liquid product commonly called LDP according to the English acronym "Liquid Dairy Products", such as dairy products in particular, or similar, distributed in a cold chain or at room temperature (aseptic). The invention also relates to a preform and a mold for the manufacture of such containers. State of the art

[0002] It is well known that a plastic container is obtained by blowing or stretch-blowing a preform within a mold with the imprint of the container.

[0003] Prior to blowing, with or without stretching, the preform is heated until its constituent material reaches or exceeds its glass transition temperature. For example, in the case where the container is made of polyethylene terephthalate, the glass transition temperature is around 70°C and can approach 80°C, depending on the formulation of the material.

[0004] Plastic containers usually comprise a body extending along a longitudinal axis, and of substantially cylindrical shape of revolution around the longitudinal axis, a base, which closes the body at a first end thereof, a shoulder, which extends in the extension of the body from a second end thereof and a neck surmounting the shoulder and having an opening. In addition, according to a conventional design, the bases are stiffened by giving them a hollow shape defining an arch intended to resist different stresses, said base being able to incidentally comprise radial stiffeners. These bases also define a plane for placing the containers. That is to say that a container can be placed on its base, in a stable manner.

[0005] Furthermore, in the field of packaging, containers in the form of small bottles with a capacity of less than or equal to 150 ml are well known and are intended to contain LDP products according to the English acronym "Liquid Dairy Products", such as dairy products in particular, distributed in a cold chain or at room temperature (aseptic), liquid or semi-liquid such as drinking yogurt containing probiotics or not.

[0006] These containers are usually obtained either from high density polyethylene commonly called HDPE or HDPE according to the English acronym “High Density PolyEthylene” or from polystyrene. Containers obtained from HDPE or polystyrene are described in documents JP2002363297, EP2012999 and US4595552 in particular.

[0007] Document JP2002363297 describes a bottle made of HDPE, which is lightweight, yet maintains the transparency required for food bottles, is rigid, impact-resistant, and exhibits good dimensional stability and does not alter the taste of the contents after long-term storage. This plastic bottle for food has a layer of high-density polyethylene having a density greater than 0.950 g.cm 3 and a molecular weight distribution of 7.5 145 defined by Mw (weight average molecular weight) / Mn (number average molecular weight) and is formed to have less than 80% bottle haze converted to a thickness of 0.5 mm.

[0008] This type of HDPE container nevertheless has the disadvantage of being difficult to recycle in a closed cycle, i.e. an HDPE bottle can hardly be recycled into a new HDPE bottle, the cost of a recycled HDPE bottle known as rHDPE being particularly high due to the difficulties of recycling.

[0009] Also known is document EP2012999 which describes a method for manufacturing a plastic container, in particular a plastic bottle, according to which a preform made of polystyrene is heated and introduced into a mold cavity of a blow mold of a stretch-inflate forming system. The preform is inflated by an injected gas under overpressure, usually air, according to the cavity of the blow mold and is simultaneously stretched by a stretching rod. The container thus blown is then demolded. The method is characterized in that the polystyrene preform is introduced into the mold cavity, said preform having been manufactured with an average wall thickness of approximately 1.6 mm to 3.4 mm, and in that the preform is subjected to a stretch-blow process carried out at a blowing temperature of 125°C to 140°C.A preform specifically suitable for the method according to the present invention and made of special polystyrene is also described.

[0010] Furthermore, document US4595552 describes an injection molding device for forming molded polystyrene articles comprising a polymer (polystyrene) supply source, a mold cavity, a conduit 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 conduit and having an elongated central passage terminating in an outlet orifice and a needle positioned in oblique relationship with the elongated central passage and selectively insertable into the orifice in a closed and retractable position of the orifice and the central passage elongated to provide unrestricted polymer flow in an open position.

[0011] Such a device allows the temperature of the molten polystyrene to be lowered during injection molding without producing undesirable physical effects in the parison being formed. Indeed, since polystyrene has lower strength characteristics than most plastics used in bottles, the wall thickness of a polystyrene bottle must generally be greater than that of other plastics. Thus, the parison used to produce the blow-molded polystyrene bottle must also be relatively thick. However, the increased thickness of the polystyrene bottle poses a significant problem from the point of view of production costs.Since the injection-molded parison is thicker than most parisons used in forming plastic bottles, the cooling time of the polystyrene parison must be longer to avoid crystallization or similar phenomena caused by rapid cooling that negatively affect the strength and other characteristics of the finished parison. Since the cooling time of the parison is a critical economic parameter, it is desirable to heat the polystyrene to the lowest possible temperature that still allows proper flow of the polymer in 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, appear in the parison being formed and / or in the subsequently formed blow-molded bottle.

[0012] Although the device avoids these drawbacks, polystyrene bottles still have the disadvantage of being expensive to recycle. Indeed, recycling polystyrene (PS) requires mechanical and chemical processing, which makes recycling polystyrene expensive. Therefore, manufacturing bottles from recycled polystyrene is too expensive.

[0013] There is therefore a need for the manufacture of low-capacity bottles, i.e. a capacity less than or equal to 150 ml, obtained from a recyclable and inexpensive material such as polyethylene terephthalate (PET) with the lowest possible weight while having good blowability for high-speed manufacturing with perfect control of material distribution. Indeed, the quest for material savings and reduction of polluting emissions is preponderant.

[0014] The invention aims in particular to meet this need. Disclosure of the invention

[0015] One of the aims of the invention is therefore to meet this need and to remedy the drawbacks of containers obtained from HDPE or polystyrene by proposing a container, a preform and a mold of simple and inexpensive design, requiring a small quantity of material and having low pressure blowability which allows high production rates while maintaining good rigidity.

[0016] For this purpose, and in accordance with the invention, a container is provided which is obtained by blow molding or stretch blow molding from a polyethylene terephthalate (PET) preform, which comprises a body, a shoulder in the extension of said body at an upper end thereof, a neck in the extension of the shoulder, said neck being open and forming a rim of the final container formed from said preform, and a bottom which extends to a lower end of the container, said container being intended to receive a liquid or semi-liquid product commonly called LDP according to the English acronym "Liquid Dairy Products" called aseptic, such as dairy products in particular, or similar, distributed in a cold chain or at room temperature (aseptic) and having a capacity of less than or equal to 150 ml,remarkable in that the height of the container from the rim to the bottom of the container is less than or equal to 120 mm and in that the ratio of the external diameter of the body to the external diameter under the neck is between 1.3 and 2.3, the height of the neck being less than 15 mm.,

[0017] Such characteristics provide good blowability even at low blowing pressure, a sufficiently rigid container while having a particularly low weight, of the order of 5 grams for a 150 ml container. Thus, in addition to the fact that PET is recyclable in a closed circuit, the container according to the invention allows the manufacture of containers at a very low cost due to its good blowability at low pressure, which allows high manufacturing rates, and the small quantity of material (PET) for its manufacture.

[0018] Preferably, the ratio between the area of ​​the container under the neck, expressed in cm 2and the weight of said container, expressed in grams, is between 18 and 45.

[0019] Furthermore, the external diameter under the neck is preferably less than or equal to 31 mm and the maximum external 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 stiffeners, said stiffeners improving the rigidity of said container.

[0021] In addition, the base comprises a peripheral seat and a concave central dome, in the form of a substantially spherical cap with a concavity facing the outside of the container, said central dome being rigid or semi-rigid.

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

[0023] In this regard, said central dome may comprise a plurality of radial stiffeners extending substantially from the center of said central dome to the peripheral seat.

[0024] Additionally, the body has an annular groove between the central part of the body and the neck, forming a constriction which improves the grip of the container in particular.

[0025] Another subject of the invention relates to a preform intended for forming containers by blow molding or stretch blow molding according to the invention, said preform being made of polyethylene terephthalate (PET) and comprising a neck, a body and a bottom, said body being symmetrical in revolution around a central axis C, having a cylindrical portion of revolution and being formed by a wall which has an external skin and an internal skin, the bottom being located at one of the ends of the body, closing the latter, and the neck extending in the extension of the body at the opposite end of the body, said neck being open and forming a rim of the final container formed from said preform;said preform is remarkable in that it has a height from the rim to the bottom less than or equal to 50 mm, an external diameter of the body less than or equal to 25 mm and a thickness of the wall of the body, that is to say the thickness between the internal skin and the external skin, between 1.2 and 2.0 mm.;

[0026] Preferably, the bottom of the preform has a substantially hemispherical shape and an external radius of curvature of between 6 and 13 mm.

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

[0028] A final subject of the invention relates to a mold for manufacturing a container by blow molding or stretch blow molding of a polyethylene terephthalate (PET) preform according to the invention, said mold comprising at least one mold base capable of being mounted movably in a side wall which defines a cavity in the impression of a part of the container, said side wall comprising two half-molds each defining a half-impression of the body of the container and mounted in rotation relative to each other, between a so-called open position, in which the half-molds are angularly spaced from each other and the mold base is lowered relative to the half-molds to allow the introduction of the blank and the evacuation of the formed container, and a so-called closed position, in which the half-molds are applied against each other and trap the mold base between them to thus form the cavity and define the total impression of the container to be formed;said mold is remarkable in that the half-cavities of the side walls and / or the mold base are shaped to produce a container according to the invention.; Brief description of the drawings

[0029] Other advantages and characteristics will emerge more clearly from the following description of several variant embodiments, given as non-limiting examples, of the container, the preform and the mold for the production of said container in accordance with the invention, with reference to the appended drawings in which:

[0030] [Fig.1] is a perspective view of the container according to the invention;

[0031] [Fig.2] is a side view of the container according to the invention shown in [Fig.l];

[0032] [Fig.3] is a bottom view of the container according to the invention, that is to say a view representing the bottom of the container;

[0033] [Fig.4] is a side view of a preform according to the invention for the manufacture of a container according to the invention;

[0034] [Fig.5] is an elevational view of the preform shown in [Fig.4];

[0035] [Fig.6] is a partial perspective view in transparency of a mold for the manufacture of a container according to the invention from a preform according to the invention. Method of carrying out the invention

[0036] In the following description of the container according to the invention, the same numerical references designate the same elements. The different views are not necessarily drawn to scale.

[0037] With reference to figures 1 to 3, a container 1 is shown, in this case a bottle, produced by stretch blow molding from a preform made of thermoplastic material such as PET (polyethylene terephthalate) which will be detailed a little later.

[0038] Said container 1 comprises, at an upper end, a threaded neck 2, provided with a rim 3. In the extension of the neck 2, the container 1 comprises in its upper part a shoulder 4 widening in the direction opposite to the neck 2, this shoulder 4 being extended by a side wall or body 5, of generally cylindrical shape of revolution around a main axis X of the container 1.

[0039] It goes without saying that the body 5 may have a different shape such as a square cross-section with quarter-round edges, for example, without departing from the scope of the invention.

[0040] The container 1 further comprises a bottom 6 which extends at a lower end of the container 1. Said bottom 6, with reference to [Fig. 3], comprises a seat 7 in the form of a thin annular bead which extends substantially axially in the extension of the body 5. The seat 7 ends with a continuous flat and annular face which forms the lower end of the container 1 and defines a laying plane 8 perpendicular to the axis of the container 1, by which the latter can rest stably on a flat surface. The laying plane 8 connects outwards to an external lateral face 9 of the seat 7 (which extends in the extension of the body 5) by a fillet 10 with a small radius of curvature, that is to say of the order of a millimeter.

[0041] Towards the interior of the container 1, the seat 7 comprises an annular cheek 11, which extends axially towards the interior of the container 1 in the extension of the laying plane 8. The laying plane 8 connects inwards to the cheek 11 by a fillet 12 which preferably has a small radius of curvature.

[0042] The bottom 6 further comprises a concave central dome 13, in the form of a substantially spherical cap with a concavity facing the outside of the container and which extends in the extension of the cheek 11 (which forms a junction between the laying plane 8 and the vault 13) to a central zone 14 forming a pin 15 which extends axially projecting towards the inside of the container 1, said central dome 13 being rigid or semi-rigid. As illustrated in the drawings, the bottom 6 is also provided with a series of stiffeners 16 which extend from the central zone 14 substantially to the laying plane 8. Preferably, the stiffeners 16 do not extend beyond the laying plane 8, that is to say they do not overflow onto the external lateral face 9. In this particular embodiment, there are 5 stiffeners 16; however, this number is provided as an example and could be different.

[0043] Furthermore, it goes without saying that said stiffeners can extend beyond the laying plane 8 by projecting onto the external lateral face 9 without departing from the scope of the invention.

[0044] In addition, 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.

[0045] Incidentally, the body 5 comprises between the central part of the body 5 and the neck 2 an annular groove 18 forming a constriction providing in particular a better grip on the container and improving the rigidity of the body 5 of the container 1.

[0046] According to an essential characteristic of the container 1 according to the invention, the height of said container 1 from the rim 3 to the bottom 6 of the container 1 is less than or equal to 120 mm and the ratio defined as being 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 characteristics provide good blowability including at low blowing pressure and, ultimately, a sufficiently rigid container while having a particularly low weight, less than or equal to 5 grams depending on the capacity of the container which is less than or equal to 150 ml. Low blowing pressure is understood to mean a blowing pressure of between 10 and 18 bars.Thus, in addition to the fact that PET is recyclable in a closed circuit, the container according to the invention allows the manufacture of containers at a very low cost due to the very good match between the preform and the packaging, which allows optimal weight reduction whether it is virgin PET or recycled PET (known as rPET) at extremely low blowing pressures and a maximum production rate.

[0047] Furthermore, the ratio between the area of ​​the container under the neck, expressed in cm 2 and the weight of said container, expressed in grams, is between 18 and 45, the external diameter under the neck is preferably less than or equal to 31 mm and the maximum external diameter of the body is less than or equal to 54 mm.

[0048] In order to manufacture containers according to the invention, with reference to figures 4 and 5, the preform 19 intended for forming containers by blow molding or stretch blow molding according to the invention, is obtained from polyethylene terephthalate (PET) and usually comprises a neck 20, a body 21 and a bottom 22, said body 21 being symmetrical in revolution around a central axis C, having a cylindrical portion of revolution and being formed by a wall which has an external skin 23 and an internal skin 24, the bottom 22 being located at one of the ends of the body 21 by closing the latter, and the neck 20 extending in the extension of the body 21 at the opposite end of the bottom 22, said neck 20 being open and forming a rim 3 of the final container 1 formed from said preform 19.

[0049] Said preform has a height from the rim 3 to the bottom 22 less than or equal to 50 mm, an external diameter of the body 21 less than or equal to 25 mm and a thickness of the wall of the body 21, that is to say the thickness between the internal skin 24 and the external skin 23, between 1.2 and 2.0 mm.

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

[0051] Incidentally, said preform comprises at least one additive giving the polyethylene terephthalate the property of at least partially filtering the visible spectrum of light.

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

[0053] Furthermore, with reference to [Fig. 6], for the manufacture of a container by blow molding or stretch blow molding of a preform 19 made of polyethylene terephthalate (PET) as described previously, a mold 30 is used comprising at least one mold base 31 capable of being mounted movably in a side wall 32 which defines a cavity 33 in the impression of a part of the container 1, said side wall 32 comprising two half-molds 34a, 34b each defining a half-impression 35a, 35b of the body 5 of the container 1 and mounted in rotation relative to each other, between a so-called open 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 preform 19 and the evacuation of the container 1 formed, and a so-called closed position, in which the half-molds 34a,34b are applied against each other and trap between them the mold base 31 to thus form the cavity 33 and define the total imprint of the container 1 to be formed. The half-imprints 35a, 35b of the side walls 32 and / or the mold base 31 are shaped to produce a container 1 according to the invention.,

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

Claims

Claims

1. Container (1) obtained by blow molding or stretch-blow molding from a preform (19) made of polyethylene terephthalate (PET), which comprises a body (5), a shoulder (4) in the extension of said body (5) at an upper end thereof, a neck (2) in the extension of the shoulder (4), said neck (2) being open and forming a rim (3) of the final container (1) formed from said preform (19), and a bottom (6) which extends to a lower end of the container (1), said container (1) being intended to receive a liquid or semi-liquid product commonly called LDP according to the English acronym "Liquid Dairy Products", such as dairy products in particular, or similar, distributed in a cold chain or at room temperature (aseptic) and having a capacity less than or equal to 150 ml,characterized in that the height of the container (1) from the rim (3) to the bottom (6) of the container is less than or equal to 120 mm and in that the ratio defined as being 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 (2) being less than 15 mm.,

2. Container (1) according to claim 1 characterized in that the ratio between the area of ​​the container (1) under the neck (2), expressed in cm 2 and the weight of said container (1), expressed in grams, is between 18 and 45.

3. Container (1) according to any one of claims 1 or 2 characterized in that the external diameter under 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 external 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 concave central dome (13), in the form of a substantially spherical cap with a concavity facing the outside of the container (1).

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

8. Container (1) according to claim 7 characterized in that said central dome (13) comprises one or more stiffeners (16).

9. Container (1) according to claim 8 characterized in that said central dome (13) comprises a plurality of radial stiffeners (16) extending substantially from the center of said 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 between the central part of the body (5) and the neck (2) an annular groove (18) forming a constriction.

11. Preform (19) intended for forming containers (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) being symmetrical in revolution around a central axis C, having a cylindrical portion of revolution and being formed by a wall which has an external skin (23) and an internal skin (24), the bottom (22) being located at one of the ends of the body (21) closing the latter, and the neck (20) extending in the extension of the body (21) at the opposite end of the body (21), said neck (20) being open and forming a rim (3) of the final container (1) formed from said preform (19), characterized in that said preform (19) has a height of drinking (3) at the bottom (22) less than or equal to 50 mm,an external diameter of the body (21) less than or equal to 25 mm and a thickness of the wall of the body (21), i.e. the thickness between the internal skin (24) and the external skin (23), between 1.2 and 2.0 mm.,

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

13. Preform (19) according to claim 12 characterized in that the bottom (22) has an external radius of curvature of 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 giving the polyethylene terephthalate the property of at least partially filtering the visible spectrum of light.

15. Mold (30) for manufacturing a container (1) by blow molding or stretch blow molding of 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 base (31) capable of being movably mounted in a side wall (32) which defines a cavity (33) to the imprint of a part of the container (1), said side wall comprising two half-molds (34a, 34b) each defining a half-imprint (35a, 35b) of the body (5) of the container (1) and mounted in rotation relative to each other, between a so-called open 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 evacuation of the container (1) formed, and a so-called closed position, in which the half-molds (34a, 34b) are applied against each other and trap between them the mold base (31) to thus form the cavity (33) and define the total imprint of the container (1) to be formed, characterized in that the half-imprints (35a, 35b) of the side walls and / or the mold bottom (31) are shaped to produce a container (1) according to any one of claims 1 to 10.

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