ES2303777A1 - Packaging articles, such as opaque bottles, and production method thereof - Google Patents

Abstract

The invention relates to opaque packaging articles, such as bottles, which can be used to store certain products, such as milk, such that they are shielded from visible and UV radiation. More specifically, the invention relates to: an opaque bottle which is obtained by means of injection blow moulding using a polyester-based composition, and a method of producing said packaging articles, particularly bottles. The polyester composition comprises a mineral filler containing a white pigment such as titanium oxide or zinc sulphur.

Description

Packaging items such as opaque bottles and manufacturing process of these items.

The present invention relates to articles, particularly opaque containers such as bottles, which allow storage protected from visible and UV radiation of certain Products such as milk.

It refers more particularly to a bottle opaque obtained by injection blow of a composition based on polyester and a manufacturing process for packaging items, particularly from a bottle.

Bottles of thermoplastic materials, and more  particularly of polyester such as poly (terephthalate ethylene), are increasingly used for the storage of various and varied liquids, particularly products liquid foods such as water, beer, sugary drinks soda or not usually called soda. They are also used for the storage of milk and other food materials solid or liquid

However, milk may come under different forms, depending on the treatment procedure applied, which allows conservation for more or less long periods. Thus, raw, sterilized milks should be used very quickly after packaging in bottles, unlike milk UHT (ultra high temperature) that can be stored for several months After bottling.

This very long conservation period imposes restrictions for the storage container such as a bottle or box

Indeed, the taste of milk evolves under the effects of UV and / or visible radiation. A milk that It has an altered taste through this phenomenon is described as that "has a light taste".

This evolution is due in particular to the degradation of vitamin B2 (riboflavin) in milk under the effect of a light exposure. In fact, the degradation of this vitamin in milk varies according to the intensity of the light source, the duration of exposure and also the range of wavelengths of the source
bright.

Radiation of wavelengths between 350 and 520 nm seem to be responsible for the degradation of this vitamin and therefore the alteration of taste of milk

Consequently, the containers of Storage or containers of these containers must present a very low light transmission even zero for wavelength radiation less than 550 nm and more Generally for UV radiation and visible radiation. This specification is more important the longer the period of milk storage

This restriction is very important for long-lasting milks such as UHT milks (temperature  ultra high), as well as for certain vitamin milk sensitive to radiation or for derived dairy products such as Yogurt, creams or the like.

Solutions have already been proposed for realization of containers compatible with the storage of Long-lasting milk and are widely used.

One of the most used is the box or brick of cardboard comprising several layers that allow to obtain a Null light transmission for wavelength range UV and visible.

However, the closure systems of these boxes, particularly after a first use are not practical and do not guarantee effective closure.

To remedy the inconvenience of these boxes, such as stiffness, dead space, shape, size, manageability, bottles have been proposed, particularly bottles of high density polyethylene (PEHD).

However, to obtain a level of Low light transmission, these bottles are formed by multilayer walls that can comprise three to six layers made in different materials.

Generally, the outer layers contain a white pigment consisting of titanium oxide to give a aesthetic appearance compatible with the stored product.

As an intermediate layer, a layer of low light transmission. Generally, this layer comprises a Carbon black as a light absorbing charge. Finally you can also present an oxygen barrier layer as well as adhesive layers to obtain good stability of the structure.

These bottles require procedures complex manufacturing. On the other hand, his recovery and recyclability is difficult to implement considering the presence of several different subjects.

Particularly, the invention aims at remedy these problems by proposing a new procedure for the manufacture of containers or articles, particularly of packaging, presenting a transmission of the very low light, particularly in the wavelength range between 350 and 550 nm and more generally for UV radiation and the visible radiation

Such items can be manufactured by simple procedures, already used for the manufacture of classic containers and also have the advantage of being able to Recycle easily for the same use as they are obtained from from a single material and its recycling does not degrade the intrinsic properties of the material.

To this end, the invention proposes a article manufacturing process particularly for the packaging of products such as food products shaping to a composition comprising a thermoplastic material of polyester or polyacetone and at least one opacifying load constituted by a white mineral load chosen from the group that comprises the oxides of titanium, zinc sulphide at a average concentration between 2% and 40% with respect to the total weight of the composition, preferably between 4 and twenty%.

By items for packaging, they are understood flexible layers obtained by extrusion, boxes or containers obtained by injection molding, and more particularly hollow bodies such as bottles obtained by blowing by injection.

According to the invention, the articles are formed single layer obtained from a composition such as the defined above.

According to a preferred feature of the invention, the articles obtained according to the process of the invention have a light transmission rate of less than 0.25% for wavelengths between 350 and 550 nm, particularly between 400 and 550 nm and preferably less than 0.1% in this range of lengths of
wave.

By light transmission rate, it is understood the ratio between the light intensity of the radiation coming out of the wall and the light intensity of the incident radiation applied on the wall. The measurement of these intensities is effect on radiation in a direction perpendicular to the wall surface. Thus, the transmission measured in the present invention is called "normal transmission" or "rate of normal transmission. "

This transmission rate is a function of the nature of the cargo, its concentration as well as the Article wall thickness.

Thus, the articles obtained through the procedure of the invention have a transmission rate normal less than 0.25% for wall thicknesses between  0.2 and 0.6 mm. Advantageously, the normal transmission rate is less than 0.20%, preferably less than 0.1%.

According to the invention, the mineral load is a white pigment such as rutile-shaped titanium oxides and / or anatase. These titanium oxides are in the form of particles of variable dimensions, advantageously between 0.2 \ mum and 1 \ mum.

These particles can be titanium oxide pure or can comprise a titanium oxide core and a protective coating This protective coating, which can be constituted by one or several layers of oxides of different metals and / or organic compounds, allows to decrease, even suppress, the interaction between titanium oxide and the polymer which forms the matrix of the composition.

Indeed, the appropriate loads for the invention must present properties and characteristics that allow to suppress or avoid any action that could harm to the polyester manufacturing process or its properties.

According to the invention, another mineral charge that forms a white pigment, namely zinc sulphide, allows to obtain compositions suitable for the manufacture of articles particularly packaging that have an opacification to the adequate light for a load concentration compatible with the procedures to shape the composition and its manufacture.

According to another feature of the invention, the Methods of shaping the composition according to the invention are procedures used classically to shape polyesters and the realization of articles of varied shapes and dimensions.

Items obtained according to the procedure of the invention can be films, molded parts, profiles or hollow bodies obtained by using procedures classics such as injection molding, extrusion, pultrusion or blown by injection.

Injection blow procedures put into practice for the manufacture of polyester bottles particularly used for the storage of water or of sodas, are suitable for the realization of bottles from a composition according to the invention comprising a load mineral.

The settings of the injection conditions and of blown are usual for an expert in the field and comparable to those necessary to adapt the blowing procedure by Injection to a classic polyester.

The articles obtained, particularly those bottles, are formed by a single layer of material and present an aesthetic appearance particularly suitable for storage of milk or dairy products.

The very low transmission properties of the light from the bottle walls allow the use of such bottle for the storage of milk or milk products for a very long period of several months, without noting a alteration of the taste of it. Consequently, this bottle is suitable for bottling long-lasting milk or of light sensitive milks like UHT milks, milks Vitamins or other products sensitive to the effect of light.

On the other hand, the use as matter plastic of a polyester or a polylactone allows to obtain packaging items, particularly bottles that present Good mechanical properties and can be easily recycled.

In general, the articles obtained according to the process of the invention, that is to say with a composition of polyester or polylactone comprising a chosen mineral filler Among the oxides of titanium or zinc sulfide, they are particularly suitable for storing sensitive products of the light.

On the other hand, these articles present a greater resistance to aging since the mineral load, at reflect a large part of the light radiation and absorb the UV radiation, protects polyester particularly in the center of the wall and on the unexposed surface against the effect of Luminous radiation This effect is particularly important in the case of thick articles such as profiles, for example.

According to the invention, polyester is understood as a polyester resin chosen from poly (terephthalate of ethylene), poly (ethylene naphthalate), copolymers of poly (ethylene terephthalate) or poly (naphthalate ethylene), which may contain at least one compound or units recurring crystallization delay.

It will be used below in this text the term poly (ethylene terephthalate) or PET. But nevertheless, the characteristics, procedures or uses described for This polymer also applies to poly (naphthalate ethylene).

In a preferred embodiment of the invention, the polyester resin is obtained from the ethylene glycol and terephthalic acid or its esters. These resins They are often referred to as PET.

By polyester or PET resin, it is called both a homopolymer obtained only from monomers of terephthalic acid or its esters such as dimethylterephthalate and ethylene glycol as copolymers comprising at least 92.5% in number of recurring units of ethylene terephthalate. Such polymers are preferred in the invention.
tion.

The polyester can also comprise minus a crystallization retarder allowing, particularly in the course of cooling the article molded or injected such as a preform, slow down or retard the crystallization of polyester to obtain a crystallization in crystals of very small size avoiding spherolytic crystallization and be able to manufacture an article with acceptable mechanical properties Such properties may result. Interesting in certain applications.

These crystallization retarding agents they are bifunctional compounds such as diacids and / or diols added to the monomer mixture before or during the course of polymerization of polyester.

As a crystallization retarding agent, may be cited by way of example of diacids, isophthalic acid, naphthalenedicarboxylic acid, cyclohexanedicarboxylic acid, acid cyclohexanediacetic, succinic acid, glutamic acid, acid adipic, azelaic acid, sebacic acid, and by way of example of diols, there may be mentioned aliphatic diols comprising from 3 to 20 carbon atoms, cycloaliphatic diols of 6 to 20 atoms carbon, aromatic diols comprising 6 to 14 atoms carbon and mixtures such as diethylene glycol, triethylene glycol, 1,4-cyclohexanedimethanol isomers, 1,3-propanediol, 1,4-butanediol, 1,5 pentanediol, (2,4) -3-methylpentanediol, (1-4) -2-methylpentanediol, (1,3) -2,2,4-trimethylpentanediol, (1,3) -2-ethylhexanediol (1,3) -2,2-diethylpropanediol, 1,3-hexanediol, 1,4-di (hydroxyethoxy) benzene, 2,2-bis (4-hydroxycyclohexyl) propane, 2,4-dihydroxy-1,1,3,3-tetramethylcyclobutane, 2,2-bis (3-hydroxyethoxyphenyl) propane, 2,2-bis (4-hydroxypropoxyphenyl) propane and their mixtures.

Often diethylene glycol is present in the polyesters inherently since it is formed during synthesis by condensation of two ethylene glycol molecules. According to desired concentration in recurring units comprising a diethylene glycol (DEG) residue in the final polyester, or add diethylene glycol to the monomer mixtures, or else control the synthesis conditions of polyester to limit the formation of diethylene glycol.

Advantageously, the molar concentration of diethylene glycol in the polyester with respect to the number of moles of diacid monomers is less than 3.5%, preferably less than 2% molar

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The polyester resins used for the invention have a viscosity index IV and can be in a very wide range, advantageously between 0.5 dl / g and 1.2 dl / g, preferably between 0.6 dl / g
1 dl / g.

The viscosity index IV is measured in a 0.5 g polymer solution / 100 ml of a solvent  consisting of orthodichlorobenzene and phenol (50/50 by weight) at 25 ° C, according to ISO 1628/5 of 06/15/1986. Polymer solution is obtained taking into account the weight of the load to obtain a 0.5 g polymer concentration, deducted charge.

The viscosity index is determined generally by analyzing polymer granules obtained at the end of the polymer manufacturing.

In the case of the use of compositions thermoplastics of the invention for the realization of bodies voids or bottles, this viscosity index IV can be measured at from the polymer that constitutes the walls of the bottle.

To perform this measurement, a piece of the bottle that is then cut into small pieces to allow solubilization.

Generally, the viscosity index of polyester is unaffected in the course of the procedure  manufacture of hollow bodies. However, the index of viscosity measured from the bottle wall can be less than or greater than measured from the fed granules In the injection stage. The value measured from the granules are generally very close to the one determined from the bottle

These considerations are equally applicable. for the viscosity index measured from the polyester that forms the walls of the preform obtained after the stage of injection.

The thermoplastic composition of the invention It may contain other components such as dyes, bleaches, light and heat protection agents, antioxidants, acetaldehyde extinguisher, for example. This list is provided for informational purposes only and is not limiting.

According to the invention, the composition is manufactured according to the conventional manufacturing procedures of polyesters In a preferred embodiment, the mineral load or white pigment is added at the beginning of the polymerization in the medium containing the monomers as will be described more ahead.

The process of the invention can be set. in practice also using as a matter, a composition obtained by recycling items, for example, bottle, obtained with a similar composition. As an example, the Used and collected bottles are ground into compositional particles Of polyester. These particles can be treated, for example, wash and granulate, before being used as a single raw material or mixed with a composition obtained according to the procedure next, in a bottle manufacturing process by injection molding or injection blow molding, for example.

The manufacturing process of thermoplastic compositions of the invention comprises a first esterification or transesterification stage in the presence or absence of catalyst Then the hydrolyzate or the obtained esterified is polycondensed under reduced pressure in presence of catalysts such as antimony compounds, of titanium or germanium, for example. At this stage, alcohol or water is removed to allow the reaction to progress polycondensation

According to the invention, this polycondensation is stops when the degree of polycondensation or the rate of viscosity have reached the desired value.

The polyester obtained is cast through a nozzle allowing to obtain wires that are then transformed into  granules by cutting.

These granules can undergo a treatment thermal or to increase the viscosity of the polymer (called PCS Post Condensation in phase Solide (subsequent condensation in solid phase)), or to decrease the acetaldehyde content (drying and evaporation at a temperature below that of a PCS).

According to another embodiment of the invention, to limit the evolution of the degree of polycondensation during the heat treatment described above to reduce the Acetaldehyde content, the polyester may comprise a monofunctional monomer, preferably a mono acid. The content molar in monofunctional monomer is between 0.5% in mol and 3% with respect to total diacid monomers.

Monoacids suitable for the invention are, for example, benzoic acid, naphthalene acid, aliphatic acids that have a boiling point compatible with the polyester synthesis process, that is, advantageously, at least higher than ethylene glycol or its esters or monoalcohols such as cyclohexanol or aliphatic alcohols that also have advantageously a boiling point higher than that of ethylene glycol

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Different additives can be added to polyesters of the invention either to the polymerization step or well in molten polyester before injection, such as bleaches, dyes or other light stabilizing additives, heat or antioxidants, for example.

According to a preferred embodiment, the load white mineral or pigment is suspended, advantageously in a polyester monomer to manufacture. As preferred monomer to perform this suspension, the diols used in the manufacture of polyester as ethylene glycol. Moreover, the dispersion of the mineral load in the composition is better when more homogeneous is the dispersion in the monomer before the addition and that the charge is dispersed in the form of very small particles without large agglomerates.

These dispersions can be done by any known means such as classic mechanical stirrers, ultrasound, strong energy mixing devices, such as Ultra-Turrax type homogenizers.

The white pigment suspension is added, advantageously, in the reaction medium at the stage of esterification or transesterification.

The concentration of white pigment in ethylene glycol is such that the amount of ethylene glycol used to This stage can represent between 20 and 100% ethylene glycol Total required for polymer synthesis.

Additives can be used to facilitate this put on hold

However, the pigment can be added directly in the reaction medium, at different stages of the polymerization, esterification, polycondensation, in the form of powder, without thereby departing from the scope of the invention.

It can also be incorporated into the polymer, in powder form or mother mix, or concentrated solutions, after the synthesis of the polymer, directly before the granulation of the same, or by mixing with the polyester granules before fusion for feeding in the procedures of shaping such as injection molding or extrusion. This pigment it can also be added directly to the molten polymer before of feeding in the procedures to shape previous.

The use of the mother mix with high mineral load concentration, for example greater than 30% in weight, is one of the preferred embodiments of the invention. The mother mixture advantageously comprises a matrix Polyester also made of polyester. It is obtained in the form of granules and can be manufactured according to the procedure of polymerization described above or by adding the mineral loading powders in molten polyester.

Advantageously, the mother mix granules are mix with the polyester granules before introduction into the devices to shape, particularly the means of melting of the composition, or dosed in the granule flow of Polyester at the entrance of shaping devices. Also the mother mix granules can be added directly into the molten polyester.

One of the particular uses e important of these compositions and that is an object of the Present invention is the manufacture of hollow bodies such as bottles using the injection blow molding technique or items obtained by injection molding.

In these uses, the thermoplastic composition according to the invention is produced in the form of granules of more or less varied dimensions or is formed in situ in the feeding and melting devices of means for shaping, from a polyester resin that does not it comprises the mineral filler with addition either in the solid state, or by feeding into the already molten resin of the mineral filler in the form of a powder or a mother mixture, as described above.

Composition granules, resin polyester and / or mother mix are advantageously dried to obtain a moisture content of less than 50 ppm, preferably at 20 ppm. This drying stage is not mandatory if the content in Polyester moisture is low enough. In certain cases, it may be advantageous to dry only the polyester and introduce the mother mix without drying.

The granules are then introduced into injection blow molding processes for the manufacture of hollow containers such as bottles. These procedures described in numerous publications and used industrially, on a large scale, comprise a first injection stage for the manufacture of preforms. In a second stage, the preforms cooled or not overheated to blow to the desired bottle shape, possibly with a
bi-stretched

Preforms are obtained, for example, by resin fusion in a single screw injection press or double, which also allows to obtain a polyester plastic and feed it under pressure at a distributor with hubs and heated shutters, for example at a temperature comprised between 260ºC and 285ºC.

The composition is injected into at least one mold of the preform, then cooled to obtain a solid preform.  The mold is provided with cooling means adapted to control its cooling rate and avoid spherolytic crystallization that can harm the stage of blown. Quick cooling is also needed to obtain short injection cycle times and therefore high rates of production.

After solidification, the preform is ejects and either cools to room temperature to store and blow at a later stage or it is kept at a intermediate temperature and is entered directly, without other cooling, in a blowing installation as described later.

In this manufacturing process of the preforms, the polyester melts at a temperature of the order of 280 ° C, for example between 270 and 285 ° C, then injected into the molds. Advantageously, the temperature will be used lowest injection possible to limit the formation of acetaldehyde, particularly to decrease the speed of acetaldehyde formation.

On the other hand, it is advantageous that the molds are cool to a temperature between 0ºC and 10ºC. This cooling is obtained using any cooling fluid suitable, such as glycol water.

Advantageously, the injection cycle and cooling is of the order of 10 seconds to 1 minute.

The polyester that forms the preform wall obtained according to this procedure has a viscosity index between 0.45 dl / g and 1.2 dl / g, advantageously between 0.60 dl / g and 1 dl / g.

The preforms thus obtained are used generally in blowing procedures for the manufacture of bottles These blowing procedures appear and are also described in numerous publications.

They generally consist of introducing the preform in a blowing installation that involves heating means with or without overstretching.

The preform is heated at least above the Tg (glass transition temperature) of the polymer and then presopla by injection of a gas under pressure with a first pressure during a first period.

A second injection of a gas with a second pressure allows to obtain the final shape of the bottle before its injection after cooling.

Advantageously, the temperature of heating of the preform is between 80 ° C and 105 ° C. This heating is done by any adapted means, for example by infrared directed towards the surface outside of the preform. This heating is regulated advantageously to avoid obtaining a difference of temperature between the inside and outside of the preform too important.

Advantageously, the preform of the preform takes place with a first pressure between 4 • 10 5 Pa and 10 • 10 Pa (4 bars and 10 bars) for a period between 0.15 and 0.6 seconds.

The second blow is done to a second pressure between 3 · 10 6 Pa and 4 · 10 6 Pa (30 and 40 bar) for a second period between 0.3 and 2 seconds.

In a known way, you can enter also a stretching rod in the preform during the pre-blowing and / or blowing operations to partially stretch the preform.

The bottles thus obtained are made with walls formed by a single layer of material.

They have a white aesthetic appearance compatible with the storage of food products such as milk. Other colors can be obtained by associating the pigments of the invention with colored pigments that can be added in the polymerization medium or mixed with the PET granules before melting for injection molding.
tion.

As illustrated above, they can be obtained according to conventional body manufacturing procedures gaps by injection blow.

Moreover, these bottles present mechanical properties that allow its use in heat filling procedures, and the procedures comprise a stage of sterilization or pasteurization. These properties mechanics are equally suitable for storing bottles by stacking, whatever the ambient temperature of storage.

The bottles thus obtained have a normal light transmission very low. So, after a UHT milk storage for 3 months, has not been altered the taste of milk according to a group of tasters.

The invention also allows performing bottles of different capacities and of diverse forms as it is already the case for translucent polyester bottles used to storage of food products, such as the Water.

Other advantages, details of the invention, will appear in view of the examples provided by way of illustration, without limitation.

Example 1

The syntheses are carried out in an installation discontinuous consisting of two successive reactors, of steel 200 l stainless each:

The first reactor, equipped with a system of screw / well agitation and a column that allows separation of glycol and water formed, allows to perform the stage of esterification, under pressure. The second, equipped with a system screw / well agitation, allows to perform the stage of polycondensation, progressive vacuum.

In this example, the mineral load used is a rutile titanium oxide sold under the reference 2220 by the Kronos society. The average concentration in the composition obtained is 4%.

Poly (ethylene terephthalate) synthesized contains 2.3% molar isophthalic motifs, that is that the acidic monomers used are a mixture of acid terephthalic (PTA) and isophthalic acid (AIP) containing 2.3% in moles of AIP.

The ratio of the number of moles of ethylene glycol (EG) with respect to the total number of diacids is 1.20.

The catalyst used for the polycondensation is antimony oxide and its average concentration, expressed in Sb, it is 250 ppm with respect to the polymer weight theoretically obtained from the mass of monomers involved

Raw materials used

- Terephthalic acid (PTA):

103,796 kg (624.99 moles)

- Isophthalic acid (AIP):

2,444 kg (14.71 moles)

- Ethylene Glycol (EG):

47,616 kg (768 moles)

- TiO_2 rutile (2220 from KRONOS):

5,340 kg

- Sb_ {O} {3}:

36.8 kg

Preparation of the mineral load

In a stainless steel container, it introduce 35 kg of glycol (a part of the indicated 47,616 above), at room temperature, and then progressively, with powerful agitation, for example ultrasonic, the 5,340 kg of titanium oxide.

Stirring is maintained for 15 minutes, after completion of the introduction of TiO_ {2}.

The glycol oxide suspension is transferred from titanium to the esterification reactor containing the glycol supplement (12,616 kg). The acid mixture is added terephthalic and isophthalic acid with stirring. After the purge of nitrogen reactor, then placed at absolute pressure of 6.6 nitrogen bars, the temperature of the reaction mass from 25 to 260 ° C in 60 minutes, from 260 to 270 ° C in 10 minutes, and finally from 270 ° C to 285 ° C, in 40 minutes.

The esterification reaction begins when the  reaction mass temperature reaches approximately 240 ° C.

The reflux rate of distilled water is regulated so that the temperature at the head of the column is maintained at 167 - 168 ° C throughout this esterification stage.

When the water distillation ends, it takes the pressure inside the reactor at atmospheric pressure.

The antimony oxide is then introduced into the reaction mass

This is transferred to the second reactor of polycondensation, previously subjected to inert nitrogen and heated to 280 ° C.

With stirring, the reactor pressure is carried progressively at 1 mbar. In parallel, the temperature of the reaction mass at 285 ° C.

The pressure is then maintained approximately between 1 and 0.5 mbar.

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Condensation is followed by measurement from the moment of agitation.

The speed of this is progressively reduced stirring, as the viscosity of the reaction mass increases

The total duration of polycondensation at Pressure less than 1 mbar is 190 minutes.

At the end of the polycondensation, the moment of stirring reaches 81.6 mN.

The polymer obtained is cast through a nozzle to make a wire that is cut in the form of granules

Example 2

Example 1 is reproduced but folding the dough of TiO 2 rutile 2220 to obtain an equal average concentration to 8% in the composition.

The total duration of polycondensation at Pressure less than 1 mbar is 180 minutes.

At the end of the polycondensation, the moment of stirring reaches 83.8 mN.

The polymer obtained is granulated according to conditions indicated in example 1.

Example 3

Example 1 is reproduced but replacing the TiO 2 rutile by TiO 2 anatase type marketed by the company SACHTLEBEN under the trade name of HOMBITAN LO CR S M, with the same average rate of 4%.

The synthesis conditions are identical to those of the preceding examples.

The total duration of polycondensation at Pressure less than 1 mbar is 175 minutes.

At the end of the polycondensation, the moment of stirring reaches 92.5 mN.

The polymer obtained is granulated according to conditions indicated in example 1.

Example 4

Example 3 is reproduced but folding the dough from TiO_ {2} Hombitan LO CR S M from SACHTLEBEN to get a 8% concentration of TiO2 by weight in the composition.

The synthesis conditions are identical to those of the preceding examples.

The total duration of polycondensation at Pressure less than 1 mbar is 140 minutes.

At the end of the polycondensation, the moment of stirring reaches 97 mN.

The polymer obtained is granulated as in the Example 1.

The characteristics of the polymers obtained meet in table I:

TABLE I

one

Before transformation, crystallize polymer granules by vacuum storage for 16 h at 130 ° C.

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In order to verify the level of opacification of the different synthesized polymers, they have made films by pressing the granules, with heat, being the thickness of the films obtained and characterized therein order of magnitude than that of the wall of the bottles usually injected / blown.

The results obtained in residual transmission UV / visible meet in table II:

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TABLE II

2

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Residual transmissions have been measured UV / visible films obtained with Perkin spectrophotometer Elmer Lambda 9.

These essays clearly show the level very low, even null, of normal movie streaming obtained with the compositions of the invention.

These results are representative of the obtained with the walls of a bottle made with a composition according to the previous examples.

On the other hand, 0.5 bottles have been made liters of capacity with the compositions of examples 2 and 4.  these bottles have been filled with milk according to the UHT method and they have kept for 3 months with a lighting of 300 Lux, representative of store lighting. It has been organized a tasting of stored milk according to the classic procedure of Taste evaluation Milk has an unaltered taste, it is say, "no light taste."

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Example 5

The synthesis of the composition according to the invention it is carried out in a 7.5 1 discontinuous reactor, made of steel stainless.

This reactor is equipped with:

-

A agitation system with double helical band equipped with a momentum meter that allows to follow the polycondensation stage, by assessing the viscosity of the mass of reaction,

-

a column that allows to separate the water from the glycol, during the stage of esterification

This reactor operates under pressure, during esterification stage and at reduced pressure, during the stage of polycondensation

The mineral load used is titanium oxide anatase Hombitan LC-S, marketed by the SACHTLEBEN company. The average concentration of titanium oxide in The composition obtained is 8%.

The rate of isophthalic motifs and the molar ratio ethylene glycol / total number of diacid moles are the same as for Examples 1 to 4, same as the antimony oxide rate used

Raw materials used

- Terephthalic acid (PTA):

2595 g (15,632 moles)

- Isophthalic acid (AIP):

61.1 g (0.368 moles)

- Ethylene Glycol (EG):

1190 g (19.2 moles)

- TiO 2 anatase (Hombitan LC-S):

268 g

- Sb_ {O} {3}:

0.938 g

A suspension of the mineral load is prepared by introduction, in a beaker of 2 L, 900 g of glycol, at room temperature, and with stirring in a Ultra Turrax type homogenizer of 268 g of TiO2. The mixture is kept under stirring for 3 minutes.

The glycolic suspension of TiO2 in the esterification reactor as well as the complement of ethylene glycol.

After purging the reactor with nitrogen, brings the pressure to 6.6 bar absolute nitrogen.

The temperature is brought from 25 to 260 ° C in 50 minutes, it is maintained at 260 ° C for 30 minutes, and finally it takes progressively at 280 ° C, in 50 minutes.

The esterification reaction begins when the  reaction mass temperature reaches approximately 250 ° C

The reflux rate of distilled water is regulated to maintain a column head temperature of 161 - 162 ° C.

When the water distillation ends that It comes from the esterification, the pressure inside the Atmospheric pressure reactor.

The antimony oxide is then introduced hot, previously dissolved at 160 ° C in 30 ml of glycol, in the reaction mass

The reactor pressure is progressively carried at 0.7 mbar, in 80 minutes.

In parallel, the temperature is brought to 285 ° C, in 50 minutes, and it stays at that temperature.

The polycondensation is followed by measuring the stirring moment, stops when the moment reaches 2.3 mN.

The duration of polycondensation is 60 minutes

Then the polymer obtained is granulated by wire-shaped casting in a bowl with water and cut The wire in a granulator.

Example 6

Example 5 is reproduced but replacing the titanium oxide anatase Hombitan LC-S by oxide 1075 anatase titanium marketed by KRONOS, with the same average rate of 8% in the final composition.

The synthesis conditions are identical to those from example 5.

The duration of polycondensation is 53 minutes The polymer is granulated under the same conditions as in the  example 5.

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Example 7

Example 5 is reproduced but replacing the titanium oxide anatase Hombitan LC-S by oxide 1014 anatase titanium marketed by the KRONOS company, with the same average rate of 8%.

The synthesis conditions are identical to those of examples 5 and 6. The duration of polycondensation is 72 minutes The polymer is granulated under the same conditions as in the example 5.

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Example 8

Example 5 is reproduced but replacing the titanium oxide anatase Hombitan LC-S by oxide anatase titanium A-HRF marketed by society HUNTSMAN, with the same average rate of 8%.

The synthesis conditions are identical to those from examples 5 to 7. The duration of polycondensation is 80 minutes The polymer is granulated under the same conditions as in the example 5.

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Example 9

Example 5 is reproduced but replacing the titanium oxide anatase Hombitan LC-S by oxide anatase titanium A-PP2 marketed by HUNTSMAN, with the same average rate of 8%.

The synthesis conditions are identical to those from examples 5 to 8. The duration of polycondensation is 55 minutes The polymer is granulated under the same conditions as in the example 5.

The characteristics of the polymers obtained They meet in table III:

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TABLE III

3

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The results obtained in normal transmission UV / visible residual according to the method described for examples 1 to 4, meet in table IV:

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TABLE IV

4

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Example 10

This example describes the realization of preforms and bottles, using a composition according to the invention obtained by mixing a mother base mixture PET containing 60% Hombitan anatase titanium oxide LO-CR-SM (from SACHTLEBEN) with a PET polymer containing 2.1% molar isophthalic motifs and whose viscosity index is 83 ml / g. The average mixing ratio It is 13.3% of the mother mixture and 86.7% of polyester. They mix the granules of mother mix and polyester resin previously in a homogeneous way.

The preforms are manufactured by use of a HUSKY LX 160T injection press, which comprises a double print mold with a 42 mm screw diameter.

The preforms obtained have a neck of 28 mm The cycle time is 14.4 s.

The injection conditions are the following:

-

Profile of temperature of the fusion zones in the frame containing the screw: 270ºC-275ºC-275ºC-275ºC-275ºC-275ºC-275ºC-275ºC-275ºC-275ºC

-

Screw speed: 44% of the maximum speed authorized by the machine.

-

Profile Injection chamber temperature: 270ºC-270ºC-270ºC

-

Weather Injection: 2.45 s

-

Injection pressure: 34 bar

-

Cooling water temperature: input: 4.2ºC

{} \ hskip6,5cm output: \ hskip0.15cm 4.8ºC

The preforms obtained with a composition that It contains 8% by weight of TiO2 and has a weight of 27.7 g.

The preforms are blown with a press SIDEC SBO 1 injection equipped with a 500 ml bottle mold and two ovens equipped with successive infrared lamps for heat the preform according to a certain heating profile. In the following tests, the first oven and the second oven lamp settings are indicated in table V then.

The blowing conditions put into practice are indicated in table V:

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TABLE V

5

The thickness of the body of the bottles obtained It is about 350 µm.

Normal UV / visible residual transmissions of the bottles obtained are the following:

- Wall thickness:

345 \ mum

- Cut threshold:

440 nm

- Normal residual transmission

quad

λ = 400 nm: <0.01%

quad

λ = 500 nm: 0.015%

quad

λ = 600 nm: 0.03%

quad

λ = 700 nm: 0.045%

Claims (11)

1. Method of manufacturing articles, particularly for the packaging or storage of materials, characterized in that it consists in shaping a composition comprising a polyester matrix and at least one mineral filler that forms a white pigment selected from the group comprising the oxides of titanium, zinc sulphide, the mineral charge being present in an average concentration between 2% and 40% with respect to the total weight of the composition. 2. Method according to claim 1, characterized in that the titanium oxide is selected from the rutile-shaped titanium oxides and / or anatase-shaped titanium oxides. 3. Method according to claim 2, characterized in that the titanium oxide is in the form of particles coated by one or more protective layers. Method according to one of the preceding claims, characterized in that the polyester is a poly (ethylene terephthalate) or poly (ethylene naphthalate) comprising at least 92.5% in number of recurring motifs of ethylene terephthalate or naphthalate of ethylene. 5. Method according to one of the preceding claims, characterized in that the composition is obtained by mixing a polyester resin with a masterbatch comprising at least 30% by weight of mineral filler that forms the white pigment. 6. Method according to claim 5, characterized in that the masterbatch comprises a polyester resin as a matrix. Method according to one of the preceding claims, characterized in that the packaging articles are in the form of a film, molded parts, profiles or hollow bodies obtained by injection molding, extrusion, pultrusion or injection blow molding. 8. Method according to claim 7, characterized in that the hollow bodies are bottles obtained by injection blow. 9. Packaging items obtained through the method according to one of the preceding claims and that have a normal transmission of light in the range of wavelengths between 350 and 550 nm, less than 0.25%, preferably less than 0.1% for a wall thickness between 0.2 mm and 0.6 mm. 10. Article according to claim 9, characterized in that the article is a bottle obtained by injection blow, the wall of the bottle body having a normal light transmission of less than 0.25%. 11. Use of the articles according to claim 9 or 10, for the storage of milk or milk products.