OXYGEN SCAVENGING COPOLYMERS MADE FROM CYCLIC ALIPHATIC MONOMERS

Abstract

A method and system for oxygen molecule scavenging is disclosed. The system employs as a novel copolymer as the reducing agent for oxygen molecules. The copolymer is the polymerization product of cyclic aliphatic monomer and unsaturated functional polymer.

Claims

1.-20. (canceled)

21. A copolymer having carbon-carbon unsaturated bonds susceptible to reaction with oxygen molecules, comprising: a polymerization product of cyclic aliphatic monomer and unsaturated functional polymer wherein the cyclic aliphatic monomer is selected from the group consisting of glycolide, propriolactone, butyrolactone, valerolactone, caprolactone, cyclic carbonates, lactams, azlactones, and combinations thereof.

22. The copolymer of claim 21, wherein the cyclic aliphatic monomer is selected from the group consisting of glycolide, cyclic carbonates, lactams, azlactones, and combinations thereof.

23. The copolymer of claim 21, wherein the unsaturated functional polymer is selected from the group consisting of hydroxyl- functional polyalkenes, hydroxyl-functional polyalkynes, glycidyl- functional polyalkenes or glycidyl-functional polyalkynes, and combinations thereof.

24. The copolymer of claim 21, wherein the cyclic aliphatic monomer is epsilon-caprolactone.

25. The copolymer of claim 21, wherein the cyclic aliphatic monomer is present in the copolymer in a weight percent ranging from about 30 to about 70 of the copolymer and wherein the unsaturated functional polymer is present in the copolymer in a weight percent ranging from about 30 to about 70 of the copolymer.

26. The copolymer of claim 21, wherein the cyclic aliphatic monomer is present in the copolymer in a weight percent ranging from about 35 to about 65 of the copolymer and wherein the unsaturated functional polymer is present in the copolymer in a weight percent ranging from about 35 to about 65 of the copolymer.

27. The copolymer of claim 21, wherein the cyclic aliphatic monomer is present in the copolymer in a weight percent ranging from about 40% to about 60% of the copolymer and wherein the unsaturated functional polymer is present in the copolymer in a weight percent ranging from about 40% to about 60% of the copolymer.

28. The copolymer of claim 27, wherein the copolymer has a weight average molecular weight (Mw) of about 15,000-20,000, a number average molecular weight (Mn) of about 8,500-10,000, and a polydispersity of from about 1.8 to about 2.2, all as measured via Gel Permeation Chromatography (GPC) using polystyrene as a test reference.

29. The copolymer of claim 28, wherein the unsaturated functional polymer is hydroxyl-terminated functionalized polybutadiene.

30. A thermoplastic compound, comprising: (a) a thermoplastic polymer matrix; and (b) a copolymer of claim 21.

31. The compound of claim 30, further comprising a catalyst for the copolymer functioning as a reducing agent for oxygen molecules.

32. The compound of claim 30, further comprising a functional additive selected from the group consisting of adhesion promoters; biocides (antibacterials, fungicides, and mildewcides), anti-fogging agents; anti-static agents; bonding, blowing and foaming agents; dispersants; fillers and extenders; fire and flame retardants and smoke suppressants; impact modifiers; initiators; lubricants; micas; pigments, colorants and dyes; plasticizers; processing aids; release agents; silanes, titanates and zirconates; slip and anti-blocking agents; stabilizers; stearates; ultraviolet light absorbers; viscosity regulators; waxes; and combinations of them.

33. The compound of claim 30, wherein the copolymer comprises from about 0.1 to about 3 percent by weight of the compound.

34. The compound of claim 30, wherein the compound is in the form of a thermoplastic article.

35. The compound of claim 34, wherein the article is a bottle pre-form.

36. The compound of claim 34, wherein the article is a blow-molded bottle.

37. The compound of claim 36, wherein the bottle contains a perishable food or beverage susceptible to oxidation.

38. A method for scavenging for oxygen within a thermoplastic article, comprising: (a) mixing a reducing agent for oxygen molecules into a thermoplastic compound and (b) forming an article from the thermoplastic compound, wherein the reducing agent is a copolymer of claim 21, and wherein the copolymer has carbon-carbon unsaturated bonds susceptible to reaction with oxygen molecules.

39. The method of claim 38, wherein step (a) also includes mixing a catalyst into the thermoplastic compound.

40. The method of claim 38, wherein the copolymer reduces an oxygen molecule by reaction with a carbon-carbon unsaturated bond, thereby scavenging the oxygen molecule from the article.

Description

EXAMPLES

Examples 1-4

Preparation of Copolymer

[0073] Examples 1-4 concern the preparation of the copolymer from the base component and the unsaturated reducing component.

[0074] Each Example was prepared by pre-mixing 2.0 g of hydroxyl-terminated functionalized polybutadiene with 2.0 g of cyclic aliphatic monomer in a 25-ml vial, followed by placing that vial in an oil batch which had been preheated at 190 C. with stirring until the mixture in the vial became a homogenous solution, followed by adding 2-drops of catalyst and continuing the heated stirring for 10 minutes.

[0075] Table 3 shows the ingredients and the formulations.

TABLE-US-00003 TABLE 3 Ingredient Name (Wt. %) Ex. 1 Ex. 2 Ex. 3 Ex. 4 Lactide (Sigma- 49.495 49.495 Aldrich) Epsilon-caprolactone 49.495 49.495 (Sigma-Aldrich) Hydroxyl-terminated 49.495 49.495 49.495 49.495 functionalized polybutadiene (Mn = 2800) Polybd R- 45HTLO from Sartomer Company of Exton, PA) Titanium tetrakis(2- 0.990 0.990 ethylhexanolate) (Tyzor TOT from Dorf Ketal) Dibutyltin dibutoxide 0.990 0.990 (FASCAT 4214 from Arkema) Total 100.00% 100.00% 100.00% 100.00%

[0076] Gel permeation chromatography (GPC) was used to analyze Examples 1-4 for conversion and molecular weight relative to polystyrene. The test was performed with the following materials: THF HPLC grade stabilized with 0.025% BHT; Waters GPC Columns: 2Styragel HR5E THF (7.8300 mm) and 1Styragel HR 1 THF (7.7300 mm); 0.45 m Teflon syringe filters for sample filtration; Autosampler vials with crimp top and rubber seal with Teflon barrier; and Polystyrene narrow Mw standards (10): 7100000, 2110000, 1460000, 706000, 355000, 96400, 37900, 10850, 2980, 1050.

[0077] The samples were prepared as follows: Weighed20 mg of sample (resin weight, record the weight) in a 30 ml vial. Added volumetrically, 20 ml of THF. Sealed vial and allowed to equilibrate overnight. Prior to analysis, heated in an 80 C. oven for 20 minutes, then cooled down. Filled a 3 ml disposable pipette with solution and attached the membrane filter. Discarded the first ml and filled an auto sampler file with solution. Crimped the seal.

[0078] The GPC Instrument had the following settings: THF solvent, 1 ml flow rate, 40 minute run time. Sample size, 50 l. Refractive Index detector, 30 C., response100 RIU full scale. Column oven was set at 30 C.

[0079] The GPC results appear in Table 4, along with melting temperature and glass transition temperatures determined by a TA Instrument DSC Q2000 instrument at a heating rate of 10 C./min under a N.sub.2 atmosphere.

TABLE-US-00004 TABLE 4 Polymerization Evidence of Copolymer Ex. 1 Ex. 2 Ex. 3 Ex. 4 GPC Analysis Conversion 93% 97% 99% 96% Mw 9,250 9,650 9,490 8,710 Mn 20,440 20,150 17,380 19,990 Mw/Mn 2.21 2.095 2.048 1.951 DSC Melt Temperature C. 46.3 47 DSC Glass Transition Temperature C. 73.7 76.1 69.7 75 C. 4.3 7.7

[0080] GPC analysis showed that there was excellent conversion for all four reactions with polymerization of the cyclic aliphatic monomer and the polybutadiene. DSC melt and glass transition temperature results indicated that copolymer was being polymerized because of the differences between these temperatures and homopolymers of the two reactants.

[0081] It was surprising that copolymers of lactide monomer were liquids having two Tg values but no Tm even though the lactide monomer itself is a solid.

[0082] Further it was also surprising that copolymers of epsilon-caprolactone monomer were waxy solids having one Tg value and a Tm of about 47 C. because the epsilon-caprolactone itself is a liquid.

[0083] Differential Scanning calorimetry (DSC) was also then used for evaluating the performance of the copolymer as an oxygen scavenger. According to ASTM D385-06, the test method consists of heating a sample to an elevated temperature, and once equilibrium is established, changing the surrounding atmosphere from nitrogen to oxygen. For Examples 1-4, 120 C. was chosen. The time from the first exposure to oxygen until the onset of oxidation is considered the Oxidation Induction Time (OIT). Specific OIT measurement procedures were as follows:

[0084] 1) Calibrated the calorimeter instrument for heat flow, gas (O.sub.2 & N.sub.2) flow rate at 50 cc/min, and thermometer;

[0085] 2) Weighed 6-8 mg of sample in small pieces (cut if needed)

[0086] 3) Purged the sample in sample cell with N.sub.2 at flow rate of 50 cc/min for 15 min

[0087] 4) Heated the samples at heating rate of 20 C./min to the setting temperature under N.sub.2 atmosphere and record the heat flow

[0088] 5) Held the temperature at the setting temperature for 10 min in N.sub.2 and continued to record the heat flow

[0089] 6) Switched from N.sub.2 to O.sub.2 at flow rate of 50 cm.sup.3/min

[0090] 7) Held the samples at the setting point constantly in O.sub.2 and continued to record the heat flow for 100 min

[0091] 8) Collected data of initial oxidation time and peak oxidation time.

[0092] Table 5 shows the OIT results for Examples 1-4.

TABLE-US-00005 TABLE 5 OIT at 120 C. Example 1 2 3 4 Start to Immediate 24.2 Immediate Immediate oxidation (OIT), min Peak 38.2 71.2 21.2 48.2 oxidation time, min

[0093] The results of OIT demonstrated Examples 1, 3, and 4 were very fast to onset of oxidation, which can prove useful at 120 C. for those items requiring immediate scavenging for oxygen. However, for those products which are not stored at 120 C., these fast Examples 1, 3, and 4 were also believed to be useful for lower temperatures perhaps requiring the presence of a reaction catalyst such as cobalt stearate to be present.

[0094] The result of OIT for Example 2 demonstrated a faster onset of oxidation than that seen for the terpolymers of US2012100263, permitting one having ordinary skill in the art to select from different oxygen scavenging polymer systems for a variety of thermoplastic matrices for a variety of rates of oxygen scavenging effect.

[0095] It is also believed that the copolymers of the present invention can function in thermoplastic matrices to perform similarly in the experiments as performed in US2012100263, such as oxygen transmission rate (OTR), oxygen ingress at headspace for a water filled bottle, oxygen ingress in water for a water filled bottle, etc.

[0096] Therefore, without undue experimentation, one skilled in the art can compound increasing amounts of copolymer to achieve multiples of amounts of oxygen scavenging capacity to determine the rate of scavenging by the copolymer functioning as the reducing agent for oxygen molecules present or permeating over a number of months of shelf life for the plastic packaging article containing the perishable and consumable food or beverage.

[0097] The invention is not limited to the above embodiments. The claims follow.