MXPA00001804A - Copolyamide active-passive oxygen barrier resins - Google Patents

Abstract

Compositions for scavenging oxygen are disclosed. These compositions comprise copolyamides comprising over 50 weight percent polyamide segments and an active oxygen scavenging amount of polyolefin oligomer segments. The polyamide segments comprise segments derived from typical bottling and packaging polyamides such as polyhexamethyleneadipamide and polyphthalamides. The copolymers are preferably formed by transesterification during reactive extrusion and typically comprise about 0.5 to about 12 wt.%of polyolefin oligomer segments. The copolyamides provide enhanced active and passive oxygen barrier properties over similar polyester constructions and similar polyamide constructions, when used in a laminar construction. In a series of preferred embodiments, multi-layered bottles fabricated with the oxygen scavenging copolyamides of this invention are about 99.8 wt.%polyamide and suitable for recycle with other polyamide bottles.

Description

BARRIER RESINS TO THE ACTIVE-INACTIVE OXYGEN OF COPOLIAMIDE FIELD OF THE INVENTION The invention generally relates to compositions, articles, and methods for packaging oxygen sensitive substances, especially edible products. The invention relates to oxygen barrier materials having improved inactive oxygen barrier properties and also having active oxygen scavenging properties. The active oxygen scavengers of this invention are condensation copolymer substances, which can be used for bottles and packaging and have the ability to consume, deplete or reduce the amount of oxygen in or from a given medium in the solid state at ambient temperatures . The formulations are described which can be manufactured in plastic bottles and other articles and packaging films.

BACKGROUND OF THE INVENTION Plastic materials have continued to offer significant improvements to the packaging industry due to their flexibility in the design of their material and their capacity to be manufactured in different sizes and shapes commonly used in the packaging industry. The development of plastic materials Ref. 32596 on packaging items, such as films, trays, bottles, cups, bowls, coatings and liners, is already common in the packaging industry. Although plastic materials offer many benefits to the packaging industry with an unlimited degree of design flexibility, the utility of plastic materials has remained inhibited in situations where the barrier properties to atmospheric gases (mainly oxygen) are necessary to ensure a shelf life of the right product. When compared to traditional packaging materials, such as glass and steel; plastics offer inferior barrier properties, which limit their acceptability for use in packaging articles that are sensitive to atmospheric gases, particularly when exposure to atmospheric gases will cause prolonged periods of time. The packaging industry continues to look for packaging materials which offer the design flexibility of plastics and at the same time the barrier properties of glass and steel.

The packaging industry has developed a technology to improve the barrier properties of plastic containers by developing containers that offer similar improved barrier properties, but not comparable to those of glass, steel, and aluminum. By a very wide margin, polyethylene terephthalate (PET) and similar packaging polyesters have gained wide acceptance, especially for bottling applications, in view of the clarity and rigidity associated with PET bottles. The PET has made significant inroads in bottling and packaging applications at the expense of the use of glass containers, but mainly in applications where the needs for barrier properties are measured. A significant example is the use of PET for bottles of soft drinks. However, the barrier properties of PET have limited its use in the packaging of oxygen sensitive products.

It is generally accepted in the packaging industry that polyamides have superior inactive oxygen barrier properties when compared to similar polyester packaging constructions. A useful inactive oxygen barrier polymer is one that exhibits the ability to retard oxygen permeability through it when compared to the oxygen permeability through other resins. In addition, it has been reported that a polyamide known as MXD-6 has some capacity to block active oxygen. MXD-6 is poly (m-xylenedipamide), which is a polyamide made of equal molar amounts of the two monomers (1) meta-xylene diamine and (2) adipic acid. An active oxygen barrier resin is a substance capable of intercepting and eliminating oxygen (subjecting a chemical reaction with oxygen), as it tries to pass through the packaging. This method also gives the opportunity to remove unwanted oxygen from inside the package cavity, where oxygen may have been inadvertently introduced during packaging or filling. This method of providing oxygen barrier properties, where a substance consumes or reacts with oxygen is known as an "active oxygen barrier" and is a different concept from inactive oxygen barriers, which try to seal a product of oxygen via the inactive approach.

When the MXD-6 (approximately 4% by weight) is mixed with PET (approximately 96% by weight), the resulting mixture is approximately 70% as permeable to oxygen as a similar construction of unmodified PET. Probably, this 30% improvement over the unmodified PET can be attributed to the improvement in the inactive barrier properties of the aforementioned mixture. When an oxidation catalyst is added to the mixture (for example, approximately 50-200 PPM cobalt with respect to the weight of the mixture), the mixture assumes improved active oxygen exclusion properties. The permeability of 02 of the mixture is decreased under these conditions until the active 02 exclusion capacity of the mixture is exhausted. The barrier properties achieved by the mixture are suitable only for less demanding packaging requirements and therefore only with a very difficult use of the mixture. However, the MXD-6 is a relatively expensive polyamide and the use of large quantities of it in a package serves to weaken the economic viability of such packaging. The most common, lower cost polyamides, such as the well known poly (hexamethyleneadipamide), have the improved inactive barrier properties of the polyamides, but are devoid of the active barrier properties. What is necessary is a resin based on polyamide of oxygen barrier of active-inactive polyamide, which can be produced at a reasonable cost and which has sufficient barrier and oxygen exclusion properties to offer the possibility of objective conservation durations in the range of 6 months to 2 years for oxygen sensitive products. This invention relates to such need.

BRIEF DESCRIPTION OF THE INVENTION AND REVIEW OF THE TECHNIQUE PREVIOUS In a copending and assigned application commonly filed September 23, 1996 and having Serial Number 08 / 717,370, it is disclosed that certain hydrocarbons, such as polyolefins, (especially polydienes) when present in small amounts as oligomer blocks of polyolefin in a block copolyester polymer add an active oxygen exclusion capability to the packaging polyesters, which do not exhibit an active oxygen exclusion capability whatever it may be in the absence of the polyolefin oligomer blocks. The oxygen exclusion copolyesters of the aforementioned application were predominantly comprised of packaging polyester segments with only an oxygen exclusion amount of polyolefin oligomer segments present to provide the oxygen exclusion capacity required for the packaging application intended . The copolyesters of the application having Serial Number 08 / 717,370 were typically in the range of about 0.5-12% by weight of polyolefin oligomer segments with the remainder comprising polyester segments. A particularly preferred embodiment was a copolyester of about 4% by weight of polyolefin oligomer segments with the remainder being polyester segments. Such block copolyesters comprising low levels in percent by weight of polyolefin oligomer segments have properties (such as melting point, viscosity, and clarity) very similar to the unmodified polyester from which the polyester segments were derived. In particular, the layers in packages and laminar bottles having one or more layers of unmodified polyester and one or more layers of copolyester in oxygen exclusion blocks as described above were self-adhering and the packaging articles appeared to be a monolithic construction (rather than in layers).

For this invention, applicants have extended the concept of implanting high capacity oxygen exclusion polyolefin oligomer segments in polyamides forming block copolyamides comprising predominantly polyamide segments and an oxygen exclusion amount of polyolefin oligomer segments . As was the case for the copolyesters described in the application having Serial Number 08/717, 370, the copolyamides of this invention have properties very similar to the polyamide from which the polyamide segments were derived. A typical use for such polyamides comprises a layered construction, such as a packaging film or bottle wall having outer and inner layers of polyamide and a core layer of copolyamide (wherein the polyamide segments of the copolyamide are derived from of those of the polyamides of the inner and / or outer layer and the oxygen exclusion segments comprise a polyolefin oligomer). This arrangement serves to provide properties for the copolyamide layer, which are very similar to the properties of the unmodified polyamide layers, which is an important concept of this invention for sheet constructions. An important concept of this invention, however, is the incorporation of highly efficient oxygen exclusion polyolefin oligomer segments in the copolyamide, while leaving the copolyamide with properties very similar to the unmodified polyamide. The high active oxygen exclusion capacity of the described copolyamides is derived from the active oxygen exclusion capability of the polyolefin oligomer segments. As previously noted, polyamides, per se, are generally considered to have superior inactive oxygen barrier properties compared to polyesters. Thus, another important concept of this invention is the combination of superior inactive barrier properties with an active oxygen exclusion capacity when compared to the use of unmodified polyester alone or unmodified polyamide alone.

An active oxygen barrier resin is a substance capable of intercepting and eliminating oxygen (subjecting a chemical reaction with oxygen), as it attempts to pass through the packaging. The exclusion of active oxygen gives the opportunity to remove unwanted oxygen (often called oxygen from the main space) from the interior of the container cavity, where oxygen may have been inadvertently introduced during packaging or filling. This method of providing oxygen barrier properties where a substance consumes or reacts with oxygen is known as an "active oxygen barrier" and is a different concept from inactive oxygen barriers, which attempt to physically seal a product from oxygen via the inactive approach. Only active oxygen scavengers can remove unwanted oxygen (inadvertently introduced during packaging) from the package cavity. The exclusion of active oxygen implies, therefore, the consumption of a material incorporated in the wall of a container. The material is progressively consumed so that the active oxygen exclusion capacity is finally exhausted or at least decreased. However, this final decrease of the active oxygen exclusion part can be adjusted so that the decrease occurs only well after the required oxygen-free shelf life of the packaged product, which is typically one year or less.

US Patent 5,021,515 (CMB Patent) describes an OxBar oxygen exclusion system of CMB. The CMB patent relates to the use of a polyamide (mixed with polyester) as a part of active oxygen scavenger. The CMB patent discloses the use of a polyamide blended with a bottling polyester, such as PET and also regulates the presence of a catalyst, such as a transition metal. Such mixt are further developed to comprise at least one layer in a single layer or multi-layer bottle or container wall. According to the CMB Patent, the polyamide in the mixtis the part responsible for the active oxygen exclusion capacity of the mixt In a preferred embodiment of the CMB Patent, 96% by weight of PET is mixed with 4% by weight of a polyamide often referred to as MXD-6. MXD-6 is a polyamide made of equal molar amounts of the two monomers (1) diamine of metaxylene and (2) adipic acid. The PET / MXD-6 mixttypically develops in the presence of approximately 200 PPM of cobalt, which serves to catalyze the active oxygen exclusion function.

EP-A-0 507 207 discloses an oxygen scavenging composition comprising an ethylenically unsaturated hydrocarbon polymer and a transition metal catalyst.

The present invention relates to the use of copolyamides capable of removing oxygen in the solid state comprising predominantly polyamide segments and an oxygen exclusion amount of polyolefin oligomer segments. The copolyamides of this invention typically develop in the presence of a catalyst, such as a transition metal, and comprise at least one layer of a single layer or multiple layer wall of a container or bottle. Significant differences between this invention and the CMB patent include (1) the current invention relates to a copolyamide comprising predominantly polyamide segments, while the CMB patent discloses a polyester / polyamide blend, which is predominantly polyester (Patent CMB does not disclose the use of polyolefin whatever), (2) the polyolefin oligomer segments in the copolyamides of this invention are the parts, which react with and remove oxygen, while in the CMB Patent, the polyamide reacts with and eliminates oxygen, (3) the oxygen exclusion capacity of the copolyamides of this invention are substantially greater than those of the PET / MXD-6 mixt and (4) the copolyamides of this invention are typically used in containers and bottles based on polyamide, while the PET / MXD-6 mixtis directed to containers and bottles based on polyester (PET).

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a cross-sectional view of the preferred oxygen exclusion film and bottle wall construction.

Figure 2 is a graph which shows the oxygen exclusion propensity of a set of resins of this invention against various control resins.

DETAILED DESCRIPTION OF THE PREFERRED MODALITIES As previously noted, polyamides, in general, have superior inactive oxygen barrier properties compared to similar polyester packaging constructions. This is true for less expensive and well known polyamides, such as poly (hexamethyleneadipamide), as well as for the more exotic and rather expensive polyamides, such as MXD-6. The polyamides used for the manufacture of plastic bottles and other packaging articles can be the same polyamides from which the polyamide segments are derived in the oxygen exclusion copolyamides described in this invention. It is well known in the polyamide art to prepare the polyamides by polymerizing together (typically on an equal molar basis and in the presence of appropriate catalyst) two separate chemical monomers as described in Formula I and Formula II to form the repeating polyamide unit described in Formula III.

R1 in the dicarboxylic acid monomer of Formula I is any substituted or unsubstituted organic divalent radical and may be aromatic, aliphatic, alicyclic, or mixtures thereof. R 2 in the diamine monomer of Formula II is any substituted or unsubstituted organic divalent radical and may be aromatic, aliphatic, alicyclic, or mixtures thereof. In certain examples, R1 and R2 (both, individually and / or independently) may contain olefinic unsaturation. Such unsaturated thickeners, if present, imagine being inside the alsanse of the present invention. In addition, those skilled in the art will recognize that other forms of the species represented in Formulas I and II can be used and will still carry essentially the same polyamide as described by Formula III. For example, the mono- or di-acid halide derivatives or the mono- or diester derivatives of the diacid of Formula I would produce (after polymerization) essentially the same polyamide shown in Formula III. Similarly, substitution by certain or all four hydrogens shown in the diamine species of Formula II would produce (after polymerization) essentially the same polyamide shown in Formula III.

O O II II I. H-O-C-R1-C-O-H H2N-R2-NH2 O O II li lll. (-N-C-R1-C-N-R2) I I HH In further detail, preferred polyamide resins suitable for use in the present invention include linear polyamides, such as those wherein the dicarboxylic acid component of Formula I is selected from a list which includes aliphatic diacids, such as adipic acid, phthalic acid, isophthalic acid, terephthalic acid, the different naphthalenedicarboxylic acids, and mixtures of the above list. Preferred diamines of Formula II include polyalkylene diamines, such as hexamethylene diamine, aromatic diamines, such as xylene diamines, and mixtures of the foregoing.

Polyamides prepared from the above components are well known in the art, and can be prepared via the polymerization reaction of the dicarboxylic acid (or appropriate derivatives) of Formula I and the diamine (or appropriate derivatives) of Formula II. In many cases, suitable polyamides for use in this invention are available to be obtained from a variety of suppliers, such as the Amodel® series of polyamides available from Amoco Chemisal Company and the Zytel® series of polyamides available from Du Pont. In the selected embodiments, the present invention also contemplates the use of polyamides as a part or all of the polyamide feed.

Other suitable polyamides for use in the present invention include the branched polyamides. These branched species could be prepared using difunctional carboxylic acid type monomers primarily together with certain carboxylic acid monomers having a functionality greater than two and then polymerizing these acids with polyamines. Alternatively, the branched species could be prepared using mainly diamine monomers together with certain polyamines having more than two amine groups and then polymerizing these polyamines with multiple functional acid monomers. Examples of acids having functionality greater than two include trimellitic acid, and pyromellitic acid (or its anhydrides).

When the monomers of Formula I and monomers of Formula II react to give the repeating structure of Formula III, this type of polymerization is known as polycondensation or condensation polymerization. In the book "GLOSSARY OF CHEMICAL TERMS" by CA Hampel and GG Hawley, Von Nostrand, 1976, a definition for condensation polymerization is presented on Page 67. According to this reference, a condensation polymer is a linear macromolecule or three-dimensional hesha by the reassertion of two molecules usually with the formation of water or alcohol as a byproduct. The reaction is repetitive or multistep, since the macromolecule is formed. These repetitive steps are known as polycondensation. Among the examples given as condensation polymers are polyesters and polyamides. In Carothers of 1929 (W. H. Carothers, J. Am. Chem. Soc. 51, 2548 (1929)) a generally useful difference between two broad polymers is proposed. One of the classes of Carothers was the condensation polymers, in which the molecular formula of the unit or structural (repeating) units in the polymer lacks certain atoms present in the monomer or monomers from which it was formed, or so that it can be degraded by chemical means. The other class of Carothers was the addition polymers in which the molecular formula of the structural unit or units (repeating) in the polymer is identical with that of the monomer from which the polymer is derived. The polymers and copolymers of importance in this invention are those which Carothers would have considered to be polymers of condensation in view of their polymerization characteristics and the formulas of the repeating units in the polymers against those of the conformation monomers. In one aspect of this invention, the new sondensasion sopolymers, which predominantly segment polyamide segments and oxygen exclusion hydrocarbon segments in the effective amount to provide the required oxygen exclusion capacity, are dessibrated. As will be explained in more detail later, these hydrocarbon segments of the condensation copolymer are presently oligomers of an addition polymer.

Of course it was necessary for the applicants to focus on the evaluation and selection of appropriate hydrocarbon segments, which could be incorporated into a copolyamide and give the necessary oxygen exclusion capacity, while not adversely affecting the characteristics and outstanding properties of the polyamides. of packaging and segments derived therefrom for the copolymer. Applicants recognized and established that hydrocarbons, such as polyolefins (especially polydienes) gave good oxygen exclusion sapacity when they were added as blocks in a copolyester. As will be verified in the examples section of this specification, further analysis and experimentation confirms that the polyolefin segments in sopolyamides would divest the active oxygen exclusion savagery to the polyamides in a manner similar to that which was observed for the copolyesters that they have polyolefin oligomer blocks. Usually, the oxygen exclusion capabilities of the polyamides were better when low molecular weight polyolefin oligomers were used, typically having molecular weights in the range of 100-10,000. Especially preferred are polyolefin oligomers having molecular weights in the range of 1000-3000. Preferred polyolefin oligomers for use as hydrocarbon segments in the exlusive oxygen copolyamides are polypropylene, poly (4-methyl) 1-pentene and polybutadiene. While not a hydrosarbide material as such, the glycol oligomer of polypropylene oxide was also identified as a potentially useful oxygen exclusion substance. Of these, the polybutadiene oligomer is especially preferred, since it has a high oxygen exclusion propensity and also because it is commercially available in the form necessary to manufacture the oxygen exclusion copolyamides of this invention by the preferred method of this invention.

As previously stated, the necessary polyolefin oligomer segments are present in the copolyamides of this invention only to the extent necessary to give the desired oxygen exclusion capacity. One reason for maintaining the polyolefin oligomer segments at only the required level is to satisfy the objective of keeping the copolyamide as similar as possible to the polyamide homopolymer. In the practice, it has been ensontrado that the presensia of polyolefin oligomer segments in the range of 0.5% by weight to 12% by weight based on the weight of the copolyamide is a range of use in% by typical weight. The presence of polyolefin oligomer segments in the range of about 2% by weight to about 8% by weight based on the weight of the copolyamide is preferred. Especially preferred is the presence of polyolefin oligomer segments in the range of about 2% by weight to about 6% by weight based on the weight of the copolyamide.

The copolyamides of this invention have the ability to absorb oxygen in the vitreous solid state at ambient temperatures of 0 ° C to 60 ° C. This functional range for the copolyamides is below the vitreous transition temperature (Tg) of these sompositions. This condition is in sharp contrast to the oxygen scavengers of the prior art, which absorb oxygen at room temperature (or even colder), but still superior to the Tg. It is well understood that the gas permeability is greatly increased above the Tg when the material is no longer a solid and therefore serves to nullify the exclusion utility of such scavengers. Another important advantage of the copolymers of this invention, particularly in comparison to the oxidizable metal / elestrolite formulations, is that they eliminate oxygen in the absence of water or moisture (as well as moisture or water presensia). This allows the use of the oxygen scavenging sopolymers of this invention to package brain materials, such as electronic bulbs, dry snack foods, medical articles. This sapacity to remove oxygen in a dry environment further distinguishes the oxygen scavenging copolymers of this invention over the prior art scavengers, which require the presence of water or at least a wet environment.

Generally, the preparation of the exslution oxygen sulfonates previously discussed will take one step, the sual comprises adding functionality to at least one or more (preferably more) of the terminal sites available in the exclusion polyolefin oligomer, which is incorporated as segments in the copolyamides. The added terminal functionality must be a part capable of entering the polycondensation reactions and forming polysondensation enlases when incorporated into a polymer. It will be understood that there may be more than two terminal sites available for functionalization when there is degradation or branching in the polyolefin oligomer. In the examples where di or multiple functionality is contemplated, generally they will be multiple of the same functionality, i.e., all hydroxy, all carboxy, or all amino added at plural terminal sites of the polyolefin oligomer molecule. Those of ordinary skill in the art will recognize that this invention can be practiced even if terminal, different, but chemically compatible, terminal functional groups are present at plural terminal sites of the polyolefin oligomer molecules. As previously observed, the only requirement is that the groups of terminal functionality must be able to enter the polycondensation reactions. A non-detailed list of terminal functional groups includes hydroxy, carboxylic acid, carboxylic acid anhydrides, alcohol, alkoxy, phenoxy, amine, and epoxy. The preferred terminal functional groups are hydroxy, carboxylic acid, and amino. It will be obvious that this step in the preparation can be avoided by using polyolefin oligomers, which are already terminally functionalized in an appropriate manner and are commercially available as such. In this regard, the terminal hydroxy functional groups are especially preferred by applicants, since the hydroxy-terminated polyolefin oligomers suitable for incorporation into the oxygen exclusion copolyamides of this invention are commercially available and offer attractive properties. Further understanding of the process can be gained by considering the chemical species described by Formulas IV, V, and VI.

O O II II IV. H-O-C- (OOP) -C-O-H V. H-O- (OOP) -O-H SAW. H2N- (POO) -NH2 In Formulas IV, V, and VI, (POO) represents a part of the divalent polyolefin oligomer. Although the Formulas IV, V, and VI show difunsionality, the (POO) can only be individually controlled or can be functionalized to a degree greater than two when the degradation or branching of the (POO) offers more than two terminal functionalization sites. In Formula IV, the (POO) is finished in dicarboxi. In Formula V, the (POO) is finished in dihydroxy, and in the Formula VI, the (POO) is finished in diamino. While Formulas IV, V and VI show the forms of hydrogen for these thickeners, it will be understood by those of ordinary thickeness in the form that from one to all the hydrogens in one of Formulas IV, V and VI could be replaced by an organisium radisal, such as alkyl, cycloalkyl, phenyl and still serve the same purpose in the preparation of the oxygen exclusion copolyamides of this invention. Using the substituted forms of the species of Formulas IV, V and VI would simply produce different subproducts in the formation of the sopolymers. As noted above, this invention could be practiced with only one functional group per (POO) or with more than two functional groups per (POO). In Formulas IV, V and VI, difunctionality is shown, but it represents one of the many possible levels of functionality. The method of forming these functionally-terminated species is unimportant to the description of this invention. Commercially available forms of Formula V (suals are especially preferred) include products of Elf Attochem a -? - polybutadiene diols R20LM and R45HT.

The similarity in the chemical structure of the species represented in Formulas I and IV is easily perceived. Since polycondensation occurs by the reaction of the terminal groups, polycondensates comprising polyamide segments predominantly with certain polyolefin oligomer segments can be formed. For an easier understanding of the composition, it may be useful to think in terms of substituting the desired amount of the Formula IV species for an equivalent amount (based on moles) of the species of the Formula I by producing polycondensates having both segments of polyamide and polyolefin oligomer. As previously observed, the sopolymers are real polycondensates with the unusual characteristic that a part of the segments consists of addition polymer (currently oligomer). In this same way, the similarity of the species of Formula II and Formula VI is easily seen. The copolycondensates can be formed by substituting the desired amount of the species of Formula VI by a molar equivalent amount of the species of Formula II. The nature of the polycondensation reaction forming the polycondensates for these two types of segment substitutions would be similar to that found for the formation of the unmodified or actual polyamide. It would be expected that the by-products formed are similar as well. The species of Formula V are terminated in dihydroxy. A desired amount of these species can be replaced by an equivalent amount of the species of Formula II to produce a slightly different type of copolymer. When prepared in this manner, a condensation copolymer is formed, wherein the bonds near the polyolefin oligomer segments are polyester linkages. As will be shown later, this represents only a very small percentage, for example, of non-polyamide and copolycondensate bonds produced having certain polyester bonds are suitable for purposes thereof just as are the copolycondensates of this invention prepared with 100% enlases of polyamide between the segments. The significant issue is that the polyolefin oligomer is an oxygen exlusion sampled has been implanted in the copolycondensate as segments, in this way it provides an oxygen exclusion capacity to the formed product, while practically maintaining all the outstanding sarasteristisas of the original packaging / bottling polyamide. These techniques for the introduction of a desired polyolefin oligomer into the polycondensate subara used at low levels dessritos by the applicants provides very accurate and effective means for the dispersion of the oxygen exclusion part in all copolycondensates. The achievement of a uniform dispersion of the oxygen exclusion part in the copolycondensate while maintaining the properties of the precursor polyamide is a key facet of this invention, which further distinguishes the oxygen exclusion copolycondensates of this invention on the previous technique. The attempt to produce oxygen exclusion materials by making a physical mixture of non-functionalized polyolefin and polyamide oligomer generally produces a non-rigid emulsion, which is not useful for packaging. However, when the functionally terminated polyolefin oligomers are mixed or combined with the polyamide at temperatures in excess of 200 ° C. melting the polyamide, the copolycondensates of this invention will be formed, at least to some degree, by transesterification. Therefore, combinations and blends of polyolefin oligomers functionally terminated with polyamide, even if designated as such, may be within the scope of this invention, since the processes of blending and blending at polyamide melting temperatures produce the Sopolicondensed compositions of this invention.

The preferred polyolefin oligomer starting material is the dihydroxy terminated (POO) species having a molecular weight in the range of about 100-10,000. The preferred preferred polyolefin oligomer starting material is the dihydroxy terminated polybutadiene species (PBD) having a molecular weight in the range of about 1,000-3,000. The formed copolymers using PBD within the preferred molecular weight range will generally have a single Tg (as measured by Differential Scanning Calorimetry) of about 100-130 ° C and offer the ability to absorb oxygen at temperatures below the Tg. While single-Tg copolymers are preferred, it will be understood by those of ordinary skill in the art that multiple Tg copolymers are also applicable, since the lower vitreous transition temperature is a temperature higher than the packaging use temperature. . The benefit of having a Tg higher than the packaging use temperature is to give design flexibility to the container associated with the rigidity of the container. It is well understood that the stiffness of the container can also be controlled by the wall thickness taking into account the flexible films that are produced by descaling calibration are the sopolymers.

One objective of this invention is to produce polyamides having predominantly polyamide segments and an oxygen exclusion amount of polyolefin oligomer segments, which are capable of absorbing oxygen at ambient temperatures below their temperatures. of glass transition. This means that the copolymers remove oxygen as a solid. It is this feature which distinguishes the copolymers of this invention from many oxygen scavengers of the prior art, which are used as eliminators superior to their glass transition temperatures, that is, not as solids. Those skilled in the art will recognize the many advantages of scavengers, which are solids, including the ability to have a film or container, which can be made completely from the copolymer and still maintain its shape at ambient temperatures. For this invention, ambient temperatures means typical storage temperatures in the range of about 0 ° C to about 30 ° C. To tolerate outgoing fill applications, the ambient temperature range would be from about 0 ° C to about 60 ° C. The polymers of this invention come out as solids, even in the range of room temperature extended from about 0 ° C to about 60 ° C.

The copolymers of this invention can be produced using any form of polycondensation processes, including the continuous and / or intermittent reaction methods commonly used in the manufacture of polyamides. The only deviation in the process is that instead of using, for example 50 mol% of a species of Formula I and 50 mol% of a species of Formula II, a part of at least one of the species of Formulas IV is included, V, or VI and a corresponding molar amount of the species of Formulas I or II abstains from the polymerization process. Alternatively, the copolycondensates can be prepared by taking a polyamide and further polymerizing them with the functionally terminated polyolefin oligomer by heating the components to obtain the melt homogenization in the extruder. The heating of the extruder can be carried out under vacuum or without vacuum conditions. Those of ordinary skill in the art will recognize this form of processing as a reactive extrusion. In such reactive extrusion processes, the polycondensation is present and the product is, in part or in whole, a copolymer comprising segments of the polyamide of inisium and segments of the polyolefin oligomer rather than a simple fusion fusion of the components of home individual.

Reactive extrusion, as discussed above, is the preferred manufacturing method of the copolycondensates of this invention.

In direct polycondensation processes, the substitution of the desired amount of the functionally terminated polyolefin oligomer by about an equivalent sanctity of one of the non-modified sondensation polymer monomers results in a high molecular weight copolymer. In this case, the desired amount of functionally terminated polyolefin oligomer can replace equivalent molar amounts of one of the polyamide monomers. In the case of direct polycondensation, the amount of functionally terminated polyolefin oligomer that absorbs oxygen can be widely varied, since the resulting copolymer exhibits the desired final state properties, such as the exclusion and clarity required for the end use. destined. Generally, when they are prepared before incorporation into packaging articles, it is necessary to keep the copolycondensates in an inert medium during storage. In many examples, the oxygen exclusion capability of the copolycondensates occurs as soon as they are formed and a period of induction of oxygen exposure has elapsed. The potential to eliminate oxygen can be significantly reduced if left exposed to oxygen (or air) for prolonged periods. In addition, prolonged exposure to a high temperature in the presence of oxygen may further reduce the oxygen absorption layers of the copolymers when made in a packaging article and introduce the possibility of decomposition and thermal degradation if it is too excessive. The premature loss of oxygen exclusion capacity before the conversion of the copolymers into a packaging article can be controlled by storage in an inert medium or by addition of appropriate stabilization agents.

While the copolymers of this invention can be made by any appropriate process, the preferred method of manufacturing the copolycondensates of this invention is by reactive extrusion as described in summary above and in greater detail below and also again in the example section. of this specifisation. As part of the extrusion process of resurfacing either alone or in combination with the manufacturing step, the polyamide in the extruder is maintained under an inert atmosphere, preferably that is provided by a nitrogen layer. The functionally terminated polyolefin oligomer is transported separately to the extruder and is introduced into the mixing zone of the extruder. The introduction rate of polyamide in the extruder is adjusted to allow a sufficient residence time to melt the polyamide and cause it to react with the functionally terminated polyolefin oligomer to produce a transesterification copolymer. The preferred residence time is from about 3 to 5 minutes in the preferred temperature range of about 260-300 ° C. The functionally terminated polyolefin oligomer was introduced through a separate orifice in the extruder and the rate of introduction of the polyolefin oligomer is adjusted to provide the amount of polyolefin oligomer segments necessary to achieve the desired oxygen exclusion capacity in the copolicondensados. A typical range for polyolefin oligomer segments is from about 0.5% by weight to about 12% by weight of the total weight of the product copolycondensate. A catalyst (transesterification / transamidation) which helps to carry the transformation, such as a transition metal carboxylate, can also be optionally employed in the extruder in a range of about 10-300 PPM of the mixture in the extruder. The cobalt carboxylates are the preferred transesterification satants and the sobalto octoate is especially preferred., because it causes the reaction to proceed quickly and is somersially available at a reasonable cost and at levels of concentration ready to be used. As noted above, the transesterification reaction is allowed to proceed in the extruder for about 3-5 minutes at a temperature of about 260 ° C-300 ° C. Under these conditions, the functionally terminated polyolefin oligomer forms a copolymer with the polyamide via transesterification. For purposes of understanding, the transesterifi- cation can be considered as a reaction by means of which the func- tion-terminated polyolefin oligomer thickeners are replaced by a part of the above monomeric polyamide species originally present in the starting polyamide. Regardless of the mechanism, the copolymer is formed by functionally terminated polyolefin oligomer species individually and multiply.

When they are prepared via a reactive extrusion process, in which the pellets are formed and then stored, it is more desirable to control the amount of moisture pick up of the copolymer to minimize the need for drying prior to manufacturing in packaging artifacts. The humidity capture control can be carried out through a two-step process. First the extruded copolymer material can be cooled using a non-asusious immersion rapid cooling process before scraping into pellets as described in US Pat. No. 5,536,793. This process takes into account the preparation of low humidity pellets. The pellets are then sealed directly in moisture proof containers (eg canisters) for storage.

The pellets can be used from the storage directly in subsequent melting step steps commonly employed in the packaging industry, such as extrusion air injection molding, film casting, sheet extrusion, injection molding, melt coating . If drying is required, it is desirable to dry the pellets in a vacuum oven or in a desiccant oven, which is covered with nitrogen.

To minimize the loss of oxygen exclusion utility of the copolymer, the copolymer can be produced during the melt manufacturing step used to make the packaging article. This is dependent on the flexibility of the manufacturing process and is typically preferred for extrusion-type processes, such as extrusion in shapes or sheets. As will be explained later, the copolymers are relatively safe from the obvious attack of oxygen once they are incorporated into a bottle or film.

The additives which may also be present in the copolycondensates of this invention include thermal stabilizers, antioxidants, colorants, crystallization nucleating agents, air bubble forming agents (when foam is needed), fillers, biodegradation accelerators, etching agents, ramification, extension agents of sadena. As will be appreciated by those of ordinary skill in the art, the inclusion of such additives produces copolymers which are within the spirit of this invention. The copolymers of this invention are also suitable for use in opaque applications, such as opaque crystalline condensate trays, which would contain low levels of crystallization nucleating agents, such as polyslefins. Also, the copolymers of this invention could be used to make sealing arrangements in which the sopolymers would foam to a lower density which also serves to reduce the cost of the container. For certain applications, combinations of the copolycondensates of this invention would be useful. Typically the combination of the copolymers of this invention would be other polysondensates, especially polyamides. However, isolated immissible sombinasiones could be appropriate for applications.

While applicants prefer to manufacture the copolymers of this invention using polycondensation methods, those skilled in the art will recognize that the copolymers could be formed, under certain circumstances, by an adduction polymerization process or by a combination of polycondensation and addition polymerization. . It is previously noted that R1 in Formula I and / or R2 in Formula II may contain at least one olefinic unsaturation site. The availability of olefinic unsaturation sites in the polyamide backbone creates a compromise by means of which the polyolefin oligomer segments could be insorporated into the polyamide by an addition polymerization process. Alternatively, the availability of olefinic unsaturation sites in the polyamide backbone creates a sonde through which the unsaturated parts capable of entering the polysubstitution could be attached to the main polymer backbone by an addition type reaction. Maleic anhydride and acrylic acid are both olefinically unsaturated and are good examples of such parts, which can be attached to the main structure of polyamide in unsaturated sites by addition and srear polycondensing sites in the other end of the molésulas. These recently added polysondensation sites could then be subjected to a condensation reaction with species as described in Formulas IV, V, and VI, thus adding segments of polyolefin oligomer to the polyamide. Even when R1 and R2 of Formulas I and II are both saturated, another possible route for adding polyolefin oligomer segments is still available. The saturated polyamide chain could be reacted with an agent, such as maleic anhydride, capable of reacting are the polyamide, for example, at the polysondensation sites available at the ends of the polyamide macromolecules. Such treatment of polymers is well known in the case of tansy and is referred to as "maleassion". Once bound by the sonassion to the polyamide (either along the main structure or at the ends of the polyamide molecules), the bound maleic anhydride creates olefinically unsaturated sites, which are subjected to the incorporation of olefin oligomers by an addition type reaction. Copolyamides having polyolefin oligomer segments, which are made by any of these mixed methods are well understood by the applicants and are considered to be within the scope of this invention.

The packaging polyamides of this disclosure are well known in the art. They are generally prepared by polycondensation of one or more diacid species with one or more diamine species under polycondensation conditions and in the presence of an appropriate polysondensation saker. Such polycondensations to form the polyamides are also well-known and well known in the art and do not form part, per se, of the current invention. While most polyamides are subject to the benefit that is realized from this invention, certain polyamides are more sommonly used in the packaging industry and therefore are the preferred polyamides of this invention. These preferred polyamides include those having part of diacid, such as adipic acid, phthalic acid, isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, substituted derivatives of the foregoing and mixtures of the foregoing. The diamine portions of the preferred polyamides include polymethylene diamines, including hexamethylene diamine, xylene diamines, mononuclear aromatic diamines, such as benzene diamines, polynuclear aromatic diamines, such as naphthalene diamines, substituted derivatives of the previous and mixtures of the above. Those skilled in the art will recognize that various derivatives of the diacids and diamines mentioned above can be used, which will still result in the formation of the same polyamides under polycondensation conditions. Generally, the polyamide segments of the copolyamides of this invention will be comprised of segments of the polyamides, which result from the densification of the diamines and diamines listed above.

When prepared by transesterification / transamidation in a reactive extruder as described above, the copolycondensates of this invention are first typically formed into pellets and then processed into containers, bottles or films. The preferred type of container wall, bottle wall or film construction comprises a three layer pattern as shown in Figure 1. The exterior of the wall of the container or bottle 24 is formed by a thicker layer 26 of polyamide unmodified packaging and may be comprised of recycled polyamide, as it does not contact the package cavity or the packaged material. The interior of the wall of the container or bottle 22, which defines the cavity of the container is formed by a thinner layer 28 of unmodified packaging polyamide. The central layer 30 is comprised of the copolyamides of this invention. While the embodiment of Figure 1 may require special extrusion equipment, it is still preferred for the following reasons: (1) it creates a structure with a relatively thick layer of exposed polyamide, which serves as a good inactive barrier to the oxygen of the air, (2) the inner layer in contact with the packaged material is also polyamide, which has a long history of use and aseptation for the packaging of consumables, (3) solosando the copolyamides of this invention between two polyamide sheets Modified are good inastive barrier properties isolates the oxygen exclusion sopolymers from direct contact with air or oxygen and retains its oxygen exclusion capacity that is applied only to oxygen, which passes through the layers of unmodified polyamide, and (4) the copolyamide and the unmodified polyamides are of such similarity that they are bonded together when they are co-extruded without the need for or use of a layer bonding adhesive.

The preferred three layer embodiment described above is more easily accomplished by co-extruding a copolymer layer with the two layers of unmodified polyamide. The copolymer is thus chemically similar to the unmodified polyamide which the three layers uniformly adhered to each other and forms a monolithic structure upon cooling. None of the adhesives such as binding sap are required. Nevertheless, in the manufasture articles of this invention where the recoating is not important, the additional non-polyamide layers can be incorporated to improve adhesion, improve barrier properties, reduce costs. It may be possible to achieve the preferred three layer embodiment by techniques other than coextrusion, such as by coating with solutions or thermal fusion of separate layers. Any method other than coextrusion may have disadvantages of (1) reduction of exclusion potential due to unwanted and / or accidental exposure of oxygen exclusion copolymers to air or oxygen; and (2) additional processing steps. For the manufacture of bottles, the union of the three layers by the adhesives would have an effect against the objective of recyclability unless the adhesive was polyamide based or compatible polyamide. For the production of films and wrappings, recyclability is not as important as it is still a consideration for bottles. In fact, for films, it may even be desirable to use layers of the copolymers of this description in conjunction with layers of other materials, such as polyethylene vinyl alcohol layers and polyolefin sheets. While the immediate co-extrusion of these sopolymers may be the most preferred use for them, other usage options are also available. For example, the sopolymers could be combined as a concentrate with other polyamides for the manufacture of film or bottle, or used as a coater or inner layer in a multilayer construction direction, for example, in the packaging of electronic components.

In a prinsipal embodiment, then this invention desserts a laminar somposision that comprises at least one layer of a packaging material and at least one layer of an active oxygen exclusion copolyamide of this invention, wherein the copolyamide comprises predominantly polyamide segments and an amount of astigating oxygen exclusion of polyolefin oligomer segments. Predominantly, as used above, it means that the sopolyamide is at least 50% by weight of polyamide segments. Typically, the polyolefin oligomer segments comprise about 0.5 to about 12% by weight of the sopolyamide, preferably about 2.0 to about 8.0% by weight and more preferably about 2.0 to about 6.0% by weight of the copolyamide. The layer of packaging material is typically a thermoplastic packaging material. A list of preferred thermoplastic materials can be found in US 21 CFR § 177.1010-177.2910, revised as of April 1, 1997. However, the copolyamides of this invention can be used as asthmatic oxygen scavengers to provide oxygen from spasm. prinsipal in the form of an internal re-lift in canisters or jars / glass bottles. In these applications, the layer of packaging material would comprise metal or glass. A preferred layer of packaging material comprises polyamide and polyamides are especially preferred from which the polyamide segments in the sopolyamide are derived. Another preferred sampler of packaging material is polyester, especially bottling polyesters, such as those listed in US 21 CFR § 177.1590, revised as of April 1, 1997. The use of the copolyamides of this invention in a laminar construction also comprising a polyester layer is especially attractive when inactive gas barrier properties beyond those available, for example, from PET, are necessary. In particular, beer bottles must be capable of not only keeping oxygen out and removing oxygen from the main space, but must also serve to prevent carbon dioxide from escaping from bottled beer. An exclusion layer based on polyamide would provide a superior inactive barrier to reduce the escape of carbon dioxide from the beer onto an exclusion layer based on polyester.

When desired for certain applications, the methods are available to make the oxygen exclusion properties of these insoluble sopolymers more effective. For example, an oxidation catalyst could optionally be added to the copolymer during the product manufacturing step. This is a separate addition of catalyst to aid in oxygen uptake and is also a residual oxidation catalyst, if any, left over from the copolymer formation. The presence of such a catalyst when added and used in the range of 10 to 2,000 PPM are the weight of the sopolymer serves to fasilitate the propulsion of oxygen uptake, often dramatically. The preferred catalysts are the multivalent transition metals, such as iron and manganese. Cobalt is especially preferred.

The copolymers of this invention can be used in conjunction with other oxygen systems. For example, a modality for improved oxygen exlusion for fabricated products of this invention comprises the optional inclusion of photoactivators (such as small benzophenone sanctities) in the products manufactured together with the copolymers of this disclosure. Manufactured products, such as bottles, containing the optional photo-ettractive materials, as well as the copolymers of this description, would be exposed to sufficient UV light to activate the photo-matting materials to the oxygen saptasion before use (ie desir, filling the bottle) or manufactured produg twill.

In still a different improved embodiment, the additional oxygen exclusion materials are developed within the package cavity together with the use of the copolymers of this description, which would comprise the packaging material. Typically, these additional oxygen scavengers would take the form of a sachet, especially for non-consumable oxygen-sensitive materials, such as electronic components. For consumable oxygen sensitive substances, additional oxygen exclusion materials could take the form of a mat as is often used in butcher shops under a cut of meat or poultry. The additional oxygen scavenger may also be developed in the form of a bottle cap layer. In many embodiments of this technique, the additional oxygen scavenger employed is one which is a completely different system than the copolyamides of this invention.

In yet another improved embodiment, the copolymers of this breakdown are developed as an internal re-lift for a container or can of glass or metal can, either alone or together with coating polymers for the glass / metal container. At each site, both inactive and active oxygen barriers are present, since the glass / metal vessel itself is a barrier to inactive oxygen. In each case, the copolymers of this disclosure are prepared to comprise a thermoset resin, or a resin mixture, which could be spray coated onto the interior walls of the container. A sprayable resin could be made more easily by mixing a small amount of a copolymer of this invention with a thermosetting resin normally used to coat canisters. It may be necessary to prepare the copolymer with a higher percentage of polyolefin oligomer segments than 12% by weight in order to require only minimal sanctity of the mixed agent with the sprayable resin. The benefit of a coater for the glass / metal filter comprising an active oxygen scavenger is that it gives the opportunity to dissipate oxygen from the main space. The use of a can can liner to remove oxygen from the main space of an edible can of food can is much more appetizing than the use of a sachet or other article, which must be separated from the product and discarded by the consumer. .

As has been indicated in several examples already, the recycling of bottles made using the copolymers of this description is an important inventive aspect of this description. In addition, the manufactured bottles should be suitable for recycling with other polyamide bottles without the need for any special processing, such as delamination or depolymerization. A quick review of the materials present in the bottles manufactured of this invention shows how the recycling requirements have been adequate. Figure 1 shows a cross-section of the construction of the preferred bottle wall. In Figure 1, layers 26 and 28 are preferably comprised of unmodified packaging polyamide. The outer surface 24 is defined by the thicker layer of polyamide (the sual may already be recycled polyamide) and the inner surface 22 (ie, the cavity of the container or bottle) is defined by the thinnest layer 28 of virgin polyamide typically . The core layer 30 is comprised of the oxygen exclusion copolymers of this invention. For a typical bottle of approximately a half-liter capacity, the oxygen exclusion copolymer layer of the bottle represents approximately 5% by weight of the entire bottle. The remaining 95% of the bottle is unmodified polyamide. Under the most dissimilar twill conglomerates of the copolymer with about 12% polyolefin oligomer, the sopolymer sheet is still 88% by weight of polyamide / polyamide segments and is typically 96% by weight of polyamide with the percentages used. most preferred of polyolefin oligomer segments. This means that the final manufactured bottle is at least 99.4% by weight of polyamide and typically 99.8% by weight of polyamide. It is this percentage by high weight of polyamide in the manufactured bottle, the sual makes it suitable for recycling with other polyamide bottles.

The primary application for the oxygen exclusion copolymers of this disclosure will be for manufacturing in packaging walls and packaging articles previously cited in several examples in this description. An important use for these manufactured articles includes the packaging of perishable foods and perishable items. A non-limiting list of perishable foods particularly subject to packaging described in this description would include daily products, such as milk, yogurt, ice cream and cheeses, prepared foods, such as stews and soups, meat products, such as hot dogs, assorted meats, chicken cesarean and beef sarne, single service items, such as presosidos foods and additional dishes that accompany the main of a pre-cooked meal, ethnic offerings, such as pasta and long noodle sauce, condiments, such as barbecue sauce , satsup, mustard and mayonnaise, drinks, such somo fruit juice, brains food, such as sour fruits, brains and sereal breakfast vegetables, baked goods, such somo bread, cookies, cakes, sweet muffins and muffins, bossed foods, Such somo caramel, potato chips and cheese-filled snacks, pasta, such as casahuate butter, peanut butter and gelatin combinations , jams and gelatins, and condiments either dry or fresh. Generally, the described copolymers and the packaging made thereof can be used to increase the barrier properties in packaging materials intended for any type of product, whether it is food, beverages or other, which degrade in the presence of oxygen . In essence, the packages made comprising the active copolyamides of this invention serve to prolong the shelf life of oxygen sensitive products. The sopolyamides of this invention are also subject to the use for the packaging of a wide variety of non-food articles, since they have the ability to eliminate oxygen in either the presence or absence of water or moisture.

EXAMPLES OF SERIES NO, 1 PREPARATION AND PROPERTIES OF COPOLYAMIDE The copolymers mentioned in Tables 1 and 2, unless otherwise indicated, were prepared in the manner described herein. Preparations were made in a co-rotating two-screw extruder ZS-30 Werner and Pfleiderer are fully entangled screws having a length-to-diameter ratio of 45: 1 screw. The ZSK-30 extruder was also equipped with a pellet feeder feeder. The amorphous polyamides used were either AMODEL® 2010 or ZYTEL® 330 resin pellets, which were first dried overnight at 125 ° C in a desiccant oven. The AMODEL® 2010 resin is a polyphthalamide comprising about 40 mol% of diacid terephthalic derivative portions and about 60 mol% of isophthalic diacid derivative portions and 100 mol% of hexamethylene diamine (HMDA) as the diamine portion. The ZYTEL® 330 resin is a polyphthalamide comprising about 30 mol% of diacid terephthalic derivative portions and about 70 mol% of isophathalic diacid derivative parts and 100 mol% of (HMDA) as the diamine portion.

The dried polyamide pellets were introduced to the feed portion of the extruder via the weight pellet feeder under a nitrogen gas blanket. The hydroxy-terminated polybutadiene oligomer (PBD) was kept in a vessel for viscous fluid under a nitrogen gas pressure from which it was separately transported via a positive displacement pump to the molten polyamide through an injection orifice in the extruder The oligomer used was a PBD diol of approximately 1230 molecular weight (R20LM available from Elf Attochem). The feed ratio of polyamide was fixed at 6.7 kg / hr (14.8 lb / hr), while the PBD was fed at a ratio of about 28 g / hr (0.062 lb / hr) to obtain a copolyamide having about 96% by weight of polyamide segments and about 4% by weight of PBD segments. The residence time of the extrusion was in the range of approximately 3-4 minutes and the temperature profile for the reactive extrusion was maintained in the range of 280-300 ° C. The volatile compounds generated from the reaction were removed via a vacuum pump. The extruded copolymer material was thermally cooled in a Sandvik metal belt and formed into pellets. The finished pellets were packed in aluminum foil bags resistant to moisture and gas. To keep the copolymer free from oxygen contamination, the complete linear extrusion process covered are nitrogen gas, including in the pre-discharge of the storage bags. It is noted that the copolyamides for this series were prepared in the absence of a transesterification catalyst. Optionally, a transition metal transesterification catalyst may also be employed in the extruder mixture in the range of about 50-300 ppm with respect to the weight of the extruder mixture.

The reactive extrusion resins prepared as indicated above were evaluated by oxygen absorption, thermal properties, inherent viscosities, molecular weight distributions, mechanical properties, and dynamic mechanical properties. A part of the resulting data are summarized in Table 1. A portion of the pellets were treated with osmium tetroxide, which colored only the polyolefin oligomer (POO) segments in the copolymers. We also obtained the Erostronic Misrográfisas de Transmisión de secsiones fino soloreadas osmium tetroxide from product pellets, the suals showed segments of OOP diameter grouped in a range of size less than approximately 15 MN. The results are consistent are the formations of the copolyester polyamide entities reacted in the extruder, because (1) the IV s (inherent vissosities) for the extruded resins were greater than the starting materials, (2) due to the T ( g) 's of the slightly depressed copolymer (vitreous transition temperatures), and also (3) due to the dimensioning of the OOP diameter segment.

In Table 1, Resin 117-2B was prepared using a 50-50% by weight mixture of 117-1A and 117-2. The transition temperature T (g) was determined by differential scanning calorimetry. The inherent viscosity IV was determined by the method of the ASTM code D2857 in phenol-TCE solvent and at 25 ° C and is given in units of dl / g. Molecular weights Mn and Mw were determined by gel infiltration chromatography (ASTM D3593 and ASTM D4001) using A-8OMS Shodex columns and hexafluoroisopropanol with sodium triacitate buffer as solvent. The Izod impact strength was determined by the ASTM D-256 code method and is given in units of kg-m / cm (ft-lb / in) slit.

Table 1 EXCLUSION OF OXYGEN FROM COPOLYAMIDE - SERIES 1 The resins of the Series 1 preparations were evaluated by oxygen uptake by placing 25 g of pellets in 500 ml ball jars equipped with sample septa. The samples were stored at 60 ° C in an oven, and the oxygen content of the jars was checked on a Mocon HS750 oxygen analyzer by the extraction of 2 cubic centimeters (cs) of aliquots at regular intervals. The data obtained are shown in Table 2 and are graphically represented in Figure 2. The resin ID numbers in Figure 2 and also in Table 3 are preceded by the sequencing of character "19440", which was a number of internal control for the project and should be ignored in the interpretation of the results. It is easily distinguished from these data that the copolyamides of this invention have a substantial oxygen exclusion capacity. In this way an important objective of this invention has been achieved, since the active oxygen exclusion capacity has been added to a polyamide-based material, which inherently already has superior inactive oxygen barrier properties in comparison to the constructions of similar polyester.

The numerical values in Rows 2-7 and Columns 2-6 in Table 2 indicate the percent oxygen remaining in the air sample trapped in the 500 ml Ball jars along with the 25 g resin sample. Resin ID # 120-1 is an oxygen exclusion resin described in US Patent Application No. 08 / 717,370 and is included for comparison purposes together with the control samples of unmodified Amodel® resin Table 2 and ZYTEL®. It should be emphasized that the series of tests in Table 2 were made in the absence of cobalt or other transition metal (s) as a promoter / catalyst for the reassessment and oxygen scavenging by the sopolymer. In the test, the sopolyamides of this invention typically develop in the presensia of about 10-2,000 PPM (they are respecte to the weight of the sopolymer) of the transition metal catalyst. The transition metal catalyst is typically added to the copolymer during the manufacture of the packaging article. Cobalt is the preferred catalyst, cobalt added in the cobalt carboxylate form is especially preferred, and cobalt ostoate is very especially preferred.

EXAMPLES OF SERIES NO. 2 PREPARATION AND PROPERTIES OF COPOLYAMIDE A second series of sopolymer preparations were made using MXD-6 as the polyamide in the extruder and therefore as the source of polyamide segments in the copolyamide. The MXD-6 is poly (m-xyleneadipamide) and has been previously described in this application. The preparation for Series 2 was the same as for Series 1 through extrusion, except that the MXD-6 was used instead of the resin Amodel® or Zytel®. The MXD-6 Series 2 copolymer was extruded through a 15.2 cm slot die manufactured by Extrusion Dies, Inc. (EDI) (6 inch EDI slot die) on top of a two roll cooling chimney and then recovered as a movie in a constant tension url. After the recovery, the samples were sealed in heat-sealed folio bags. The bags were purged with nitrogen gas and sealed. The polymer feed ratios, screw speed, extruder temperatures, vacuum degree, and residence times were adjusted to maintain stable extrusion of the copolyamide film of MXD-6. Table 3 shows the values of the extruder process data used for both the Series 1 and Series 2 resins. The pure MXD-6 film was designated ID # 157-1 and the copolymer MXD-6 was 4. % by weight of PBD designated is ID # 158-1. In Table 3, all pressures listed in Columns 10-13 are indexed by the pressure gauge used.

EXCLUSION OF OXYGEN FROM COPOLYAMIDE - SERIES 2 The resins of the Series 2 preparations were evaluated by oxygen uptake by placing only 10 g of film (instead of 25 g of pellets as in Series 1) in 500 ml Ball jars equipped with sample septa. The samples were stored at 60 ° C in a furnace, and the oxygen content of the jars was verified in a Mocon HS750 oxygen analyzer by the extration of 2 superscript sentimeters (ss) of aliquots at periodic intervals. The data obtained are also represented graphically in Figure 2, together with the data of the resins of the Series 1. From Figure 2 it can be seen that 10 g of copolyamide in film form is almost as effective as 25 g of copolyamide in the form of pellets for the oxygen saptasión. There are several competitive fasteners, which make the direst somparasions difficult. The film samples allow greater access of the oxygen present to the scavenger compared to the pellet samples. Also, polyamides are better inactive oxygen barriers than polyamides that make it more difficult for oxygen to reach the exclusion part in a sopolyamide than in a sopolyester. In practice, copolyamide films are also typically developed in the presence of about 10-2,000 PPM (with respect to the weight of the copolymer) of the transition metal catalyst. The transition metal catalyst is typically added to the copolymer during the manufacture of the packaging article. As mentioned above, cobalt is the preferred catalyst, cobalt added in the cobalt carboxylate form is especially preferred, and cobalt octoate is most particularly preferred.

TABLE 3. EXTRUSOR PROCESS DATA oo As can be seen from the data of the examples, the copolyamides of this invention have a layer of active oxygen exlusion, which serves to increase their inactive and superior oxygen barrier properties compared to polyester. The copolymers described herein are more advantageously developed as a layer in a multilayer packaging construction, particularly when an additional active oxygen barrier saucer is present to protect the expelled oxygen astpolymers from this invention of the apparent oxygen attack ( of oxygen in the air) and also when an additional adjacent layer is chemically similar to the copolyamides. Those skilled in the art, however, will appreciate that variations in this basic form of development are possible and should be considered to be within the scope of this invention.

It is noted that they are relasión to this fesha, the best method sonosido by the solisitante to bring to the prástica the cited invention, is the one that slaro of the present dessripsión of the invention.

Having described the invention as above, the property contained in the following is acknowledged as being property.

Claims (14)

1. An oxygen barrier sheet composition, characterized in that it comprises a sack of packaging material and an active oxygen exclusion copolyamide sheet comprising predominantly polyamide segments and an active oxygen exclusion amount of polyolefin oligomer segments; and wherein the copolyamide exits as a solid below its glass transition temperature and the copolyamide is capable of removing oxygen in its solid state at temperatures in the range of 0 ° C to 60 ° C.

2. The sheet composition according to claim 1, characterized in that the packaging material is a thermoplastic resin.

3. The sheet composition according to claim 1, characterized in that the packaging material is a polyester resin.

4. The sheet composition according to claim 1, characterized in that the packaging material is a polyamide.

5. The sheet composition according to claim 4, characterized in that the polyamide segments in the copolyamide are derived from the polyamide packaging material.

6. The sheet composition according to claim 1, characterized in that the polyolefin oligomer segments comprise from 0.5 to 12% by weight of the copolymer.

7. The sheet composition according to claim 1, characterized in that the polyolefin oligomer is selected from the group consisting of polypropylene, poly (4-methyl) -1-pentene, polybutadiene and mixtures thereof.

8. The laminar composition of sonification to claim 1, sarasterized in that the polyolefin oligomer has a molecular weight in the range of 1000-3000.

9. A packaging article, characterized in that it comprises a container wall comprising the sheet composition of claim 1 placed inside the container wall.

10. A method of prolonging the useful shelf-life of an oxygen-sensitive substance, characterized in that it comprises packing the oxygen-sensitive substance in an appropriate packaging article comprising a container wall comprising the laminar composition of claim 1 collided within the container wall.

11. A suspension of oxygen exsussion, sarasterized because (A) comprises a copolyamide comprising predominantly polyamide segments and an active oxygen exclusion amount of polyolefin oligomer segments and (B) a transition metal catalyst present in the range of 10-2,000 PPM are based on the weight of the sopolyamide; and wherein the copolyamide is capable of removing oxygen in the solid state at ambient temperatures.

12. The oxygen exclusion composition according to claim 11, characterized in that the transition metal catalyst is cobalt.

13. The composition of oxygen exlusion of the soundness to the claim 12, characterized in that the cobalt source is cobalt octoate.

14. The oxygen exclusion composition according to claim 11, characterized in that it also comprises photoactive materials suals, after sufficient astivation by radiation, serve to increase the exclusion of oxygen from the copolyamides. BARRIER RESINS TO THE ACTIVE-INACTIVE OXYGEN OF COPOLIAMIDE SUMMARY OF THE INVENTION The invention refers to compositions to eliminate oxygen. These moieties comprise copolyamides comprising more than 50 percent by weight of polyamide segments and an active oxygen exclusion amount of polyolefin oligomer segments. The polyamide segments comprise segments derived from the typical bottling and packaging polyamides, such as hexamethyleneadipamide and polyphthalamides. The sopolymers are preferably formed by transesterifissation during reactive extrusion and typically comprise about 0.5 to about 12% by weight of polyolefin oligomer segments. The copolyamides provide improved astive and inactive oxygen barrier properties over similar polyester constructs and similar polyamide constructions, when used in a laminar construction. In a series of preferred embodiments, the multi-layer bottles manufactured are the oxygen exclusion sopolyamides of this invention are approximately 99.8% polyamide and suitable for recycling with other polyamide bottles.