Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/0008—Organic ingredients according to more than one of the "one dot" groups of C08K5/01 - C08K5/59

Definitions

• the present invention relates to polyketone polymer compositions.
• Polyketone polymers exhibit many desirable physical properties which make them suitable for engineering thermoplastic applications.
• high molecular weight linear alternating polyketone polymers possess such properties as high strength, rigidity, toughness, chemical resistance, and wear properties. While these properties are adequate for many applications it would be of advantage to further improve certain properties such as environmental stress crack resistance, chemical resistance, creep resistance, increased use temperature and increased tensile strength.
• One method known in the art for providing these improvements has involved the cross-linking of linear polymer chains of a thermoplastic polymer. .An example of this is polyethylene which can be made to exhibit increased durability, use temperature and strength through post-reactor cross-linking.
• the present invention relates to a composition
• a composition comprising a major amount of polyketone polymer and a minor amount of a iodide salt with the proviso that the composition is not a composition containing 5.0 parts per million by weight of sodium iodide, metal content on polymer. It has been found that such composition can be cross-linked to give a composition having and exhibiting improved mechanical and chemical resistant properties. Further, the present invention relates to blends containing such composi'tion.
• the polyketone polymers which are useful in the practice of the invention are of a linear alternating structure and contain substantially one molecule of carbon monoxide for each molecule of ethylenically unsaturated hydrocarbon.
• the preferred polyketone polymers are copolymers of carbon monoxide and ethylene or terpolymers of carbon monoxide, ethylene and a second ethylenically unsaturated hydrocarbon of at least 3 carbon atoms, particularly an oc-olefin such as propylene.
• the preferred polyketone terpolymers When the preferred polyketone terpolymers are employed as the major polymeric component of the blends of the invention, there will be within the terpolymer at least 2 units incorporating a moiety of ethylene for each unit incorporating a moiety of the second hydrocarbon. Preferably, there will be from 10 units to 100 units incorporating a moiety of the second hydrocarbon.
• the polymer chain of the preferred polyketone polymers is therefore represented by the repeating formula
• terpolymers are employed, the —CO- (-CH2-H2-)- units and the —CO-(G-)- units are found randomly throughout the polymer chain, and preferred ratios of y:x are from 0.01 to 0.1.
• the precise nature of the end groups does not appear to influence the properties of the polymer to any considerable extent so that the polymers are fairly represented by the formula for the polymer chains as depicted above.
• polyketone polymers of number average molecular weight from 1000 to 200,000, particularly those of number average molecular weight from 20,000 to 90,000 as determined by gel permeation chromatography.
• the physical properties of the polymer will depend in part upon the molecular weight, whether the polymer is a copolymer or a terpolymer, and in the case of terpolymers the nature of the proportion of the second hydrocarbon present.
• Typical melting points for the polymers are from 175°C to 300°C, more typically from 210°C to 270°C.
• the polymers have a limiting viscosity number (LVN) , measured in m-cresol at 60°C in a standard capillary viscosity measuring device, from 0.5 dl/g to 10 dl/g, more preferably from 0.8 dl/g to 4 dl/g.
• LPN limiting viscosity number
• a preferred method for the production of the polyketone polymers has been described in EP-A-181014, EP-A-248483, EP-A-600554, EP-A-314309 and EP-A-391579.
• the useful iodide salts are those which are capable of cross- linking polyketone polymers under appropriate conditions. Examples of these salts include those listed in Table 1.
• Linear polyketone polymers containing a sufficient (minor) amount of iodide salt can be cross-linked by subjecting the composition to the presence of oxygen at elevated temperature. While not wanting to be held to any particular theory, it is believed that some oxidation of the polyketone polymer occurs which in the presence of a iodide salt catalyzes the cross-linking reaction.
• the extent of cross-linking is controllable by the amount of exposure to heat and oxygen.
• the time required to obtain a desired level of cross-linking is inversely related to the temperature used or the oxygen content available.
• An effective oxygen source is air.
• the amount of heat required is that which is sufficient to lead to the cross-linking of the polymer.
• the required amount of heat can be obtained at a preferred operating temperature of about 70°C. While the inventive process can cross-link a polyketone polymer melt in the presence of sufficient oxygen, it is generally preferred to cross-link at temperatures below the crystalline melting point of the polymer.
• Methods known in the art for cross-linking polyethylene include (1) the use of high energy radiation, (2) thermochemical reactions, and (3) moisture induced reactions. Methods (1) and (2) rely on the initiation of free-radical intermediates either through radiation or radical initiators such as organic peroxides. In polyethylene these radical intermediates result in chemical cross-links between polymer chains; however, these methods are not applicable to all polyolefins. Polypropylene and polybutylene are examples where radical initiation does not result in cross-linking, but rather chain scission. These methods also possess certain disadvantages which are known to the skilled artisan.
• cross-linking polyethylene which utilizes moisture first requires free-radical grafting of vinyl silane units onto the polyolefin which are then capable of reacting with water to produce chemical cross-links. Since cross-linking occurs after melt processing, this method like radiation curing, allows conventional fabrication methods to be used and maintains a high degree of crystallinity after cross-linking.
• Moisture cross-linking of polyketone polymer may be possible if silane grafting could be carried out by some means other than a free-radical process. It is envisioned that a silane grafting method for polyketones is feasible if the vinyl groups commonly used in polyethylene were replaced with groups capable of reacting with ketones such as amines. Examples would include (trialkylsilyl)- alkylamines and (trialkylsilyl)aryl-amines.
• the current invention takes a linear polymer which is completely soluble in HFIPA (hexafluoroisopropanol) and cross-links it such that it becomes only swollen by the solvent.
• Suitable solvents are usually polar solvents with low molar volume, especially those having a strong hydrogen bonding characteristic. Examples of such solvents include hexafluoro-isopropanol, m-cresol, and phenol. Hexafluoroisopropanol is preferred because of its ability to dissolve the polyketone polymer at room temperature. Furthermore, it has surprisingly been found that compositions containing certain iodide salts, show improved oxidative stability.
• a disadvantage of linear alternating polymers of carbon monoxide and at least one ethylenically unsaturated hydrocarbon is that they can exhibit a deterioration of physical properties upon thermal oxidative degradation. This degradation is due to a chemical attack of atmospheric oxygen on the polymer chains and is characteristic of most, if not all organic polymers. Oxidation is typically autocatalytic and occurs as a function of heat and oxygen, hence the term thermal oxidative degradation. It is desirable to inhibit the deterioration of polymer properties by stabilizing the polymer toward the adverse effects of heat and oxygen.
• thermal oxidative stabilizers which are employed commercially to stabilize thermoplastic polymers against such degradation. However, many of the thermal stabilizers which are known to be effective with polyolefins, polyamides, polyacetals, polyacrylates, etc. are only marginally or not at all effective when employed with polyketone polymers.
• the composition comprises an onium iodide salt of nitrogen, phosphorus, arsenic, or combination thereof in which the cation coordination sphere is shielded by aromatic substituents or an alkali metal iodide, with the proviso that the composition is not a composition containing 5.0 ppmw of sodium iodide, metal content on polymer.
• the melt stability of polymers can be adversely affected by the presence of alkali (ne earth) metal salts.
• experiment 1 has been described a composition containing 5.0 parts per million by weight of sodium iodide, metal content on polymer.
• the composition of the present invention can be prepared by contacting the polyketone polymer with the iodide salt. More specifically, the methods can comprise a) melt compounding after contacting the iodide salt with polyketone polymer by powder mixing or solvent deposition, b) diffusion of the iodide salt into polymer articles by treating the polymer with a solution containing the iodide salt, preferably using a solvent which has some miscibility with both polymer and the iodide salt, or c) in- situ generation of the iodide salt utilizing a polymer blend comprising of precursors which upon application of a sufficient amount of heat generates the iodide salt.
• the iodide salt is introduced by diffusion.
• Thermal oxidative degradation of organic polymers relates to the deterioration of polymer properties due to the chemical reaction(s) between the polymer and atmospheric oxygen. While oxidation processes are complicated and mechanistic pathways of oxidation between different polymers may vary, oxidation is generally promoted by heat, often initiated by trace impurities such as metal ions or organic prodegradants, and characterized overall as autocatalytic in which carbon radicals and peroxyl radicals constitute key intermediates in the catalytic cycles. Consumption of oxygen by the polymer propagates the catalytic cycle and generates oxygenated species which either comprise part of the polymer or are evolved as gaseous products. These oxygenated species may further be prodegradative to the polymer. For example, hydroperoxides are not inherently stable and are capable of decomposing into new radicals, either thermally or catalyzed by trace impurities, which can then initiate additional oxidative cycles.
• alkali metal iodide salts such as lithium, potassium and sodium iodide are also within the scope of the invention.
• the iodide salts will generally be present in an amount within the range of from 0.0001 to 10, more specifically 0.001 to 10 percent based on the weight of the polyketone polymer, preferably in the range of from 0.1 to 1.0 percent based on the weight of polyketone polymer.
• the iodide salt is present, but also a hindered phenol, more specifically a composition, wherein the hindered phenol is benzene propanoic acid, 3,5-bis (1,1-dimethylethyl)-4-hydroxy octadecyl ester and/or benzenepropanoic acid 3,5-bis (1, 1-dimethylethyl)-4-hydroxy-l,2- ethanedyl bis (oxy-2,1-ethanediyl)ester.
• the now stabilized polyketone polymers show improved retention of desired mechanical properties, such as resistance to embrittlement when tested under conditions of elevated temperature and air exposure.
• the test as disclosed in U.S. Patent No. 4,994,511 subjects polymer samples to aerobic oven aging at various temperatures and monitors the time until brittle failure (cracking) occurs when sharply bent at an angle of 180°.
• Examples 1-5 demonstrate the utility of iodide additives to heat aging when diffusionally incorporated into polyketone polymer.
• Test specimens were prepared by immersing polymer A in the form of 5.1 x 10 -4 m (20 mil) sheet into a water composition for 20-25 min at a temperature of 90-95C.
• the water used was HPLC grade, OmniSolv supplied by EM Science.
• Water compositions used in examples 2-5 included: water alone, 0.30 wt% Znl 2 , 2.0% KI, and saturated Ph PI which is only sparingly soluble in water at 90-95 C C. After exposure, the polymer specimens were cooled, wiped clean of any surface residue, and dried in a vacuum oven at 50 C C with a nitrogen purge over night.
• Examples 2 and 3 show that simply exposing the polymer sheet to water alone or to a solution of Znl 2 does not result in improved heat stability. Exposure to KI and Ph 4 PI results in an improvement in heat stability with Ph PI being far superior in its ability to stabilize this polyketone polymer - greater than 2 times the control, Example 1. Examples 6-10.
• Test specimens used in Examples 6-10 were diffusionally prepared and then tested as described in Examples 2-5 using polymer A and water compositions which contained 2.0% of the corresponding test additive. The results are summarized in Table 4. i. ⁇
• Examples 7, 8, & 10 show that of the Ph P halide salts only the iodide is stabilizing to polyketone polymers.
• Example 9 demonstrates that alkyl ammonium iodides such as tetraethyl- ammonium iodide (Et 4 NI) are not effective in stabilizing polyketone polymers. This demonstrates that not all onium iodide salts are effective as stabilizers for polyketone polymer. Examples 11-13.
• Examples 11-13 were prepared as described in Example 1-5 with the exception that extruded sheet of polymer B was used instead of polymer A. Test specimens for examples 12 & 13 were prepared similar to Examples 7-10. Oven aging results are shown in Table 5.
• Examples 14-16 demonstrate that powder mixing of Ph PI and polyketone polymer followed by melt processing results in a polymer composition with improved thermal oxidative stability.
• Examples 15 and 16 were prepared by combining 100 grams polymer C powder with Ph PI powder and then homogenizing by tumbling overnight. Each mixture was then extruded on a 15 mm Baker- Perkins twin screw extruder operating at a melt temperature of about 250 °C. The extruded compositions were then used to make plaques of 30 mil thicknesses by compression moulding. As shown in Table 6, compositions with Ph 4 PI showed significantly improved time to embrittlement at 125 °C over the control.
• Examples 17-26 compositions were prepared by melt processing as described in Examples 14-16 with the exception that polymer D was used instead of polymer C. Oven aging test results shown in Table 7, illustrate that onium iodide salts with alkyl substituents (ex. 18-22) exhibit no stabilizing influence on polyketone polymers. Examples 25 and 26 demonstrate the stabilizing influence of iodide salts other than Ph 4 PI which also contain onium cations shielded by aromatic substituents, i.e. bis (triphenylphosphoranylidene)ammonium and a triazolium salt, respectively. In these examples, the increased stability was somewhat small, but similar in magnitude to the benefit from Ph 4 PI in this polymer, Example 24.
• Examples 27-39 compositions were prepared by melt processing as described in Examples 14-16 using the polymers and additives identified in Table 8.
• Example 30 demonstrates the improved resistance to embrittlement using only PPh 4 I.
• Example 31 shows a significant improvement when a commercial hindered phenolic antioxidant such as Irganox 1076 is combined with Ph PI in polyketone polymers. This combination results in improved oven aging performance compared to using either individually.
• Examples 33-39 demonstrate that in-situ formation of phosphonium iodides from a phosphine and an organic iodide components improves the stability of polyketone polymer just as effectively as using Ph PI.
• Examples 34-37 show that the use of either triphenyl phosphine or 1,4-diiodobenzene alone do not contribute to the stability of polyketone polymers. However, the combination of these additives in Example 33 yields a polymer with significantly improved heat aging performance. Examples 38 and 39, further show the beneficial effect when an organic iodide and triphenyl- phosphine are combined in the additive package.
• Polyketone polymer A with a melting point of about 220 °C and limiting viscosity number of 1.87 dl/g was compounded with 0.3 wt% tetraphenylphosphonium iodide (PPh 4 I) and 0.5% Irganox 1076 on a 15 mm Baker Perkins extruder operated at a melt temperature of approximately 250 ⁇ C.
• a control was prepared by extruding polymer A as described above without the use of any additives. After this, the pellets were dried in a vacuum oven at 50 C C under nitrogen and then compression moulded into 5.1 x 10 -4 m (20 mil) thick plaques.
• Test specimens were cut from the plaques in 1 cm wide strips and exposed to oxygen and heat using a Blue M forced air oven set at 125 °C. The samples were withdrawn from the oven after 11 days exposure and submitted for GPC analysis using hexafluoroisopropanol (HFIPA) as solvent. GPC analysis utilized ZORBAX 1000 and 60 PSM columns in series and a Waters 410 differential refractometer as detector.
• HFIPA hexafluoroisopropanol
• Table 1 shows that as expected of linear polyketone polymers, both unexposed samples were completely soluble in HFIPA. After exposure to heat and oxygen, polyketone polymers without iodide additives are soluble and exhibited a molecular weight loss. The polymer sample containing iodide became a swollen gel (50% sol) indicative of a cross-linked polymer. This sample, however, did not experience embrittlement in the same oven until 43 days compared to the specimen without PPh I which embrittled in only 15 days.
• Polyketone polymer B with a melting point of about 220C, an LVN of 1.95 dl/g, and containing 0.5% Irganox 1330 and 0.5% Nucrel 535, was melt extruded into 5.1 x 10 -4 m (20 mil) sheet. One centimetre wide strips of this sheet were exposed to heat and oxygen as described in Example 1. In addition to these strips, a separate set of strips was submitted to a saturated aqueous PPh 4 I solution at 85 °C for 20 min. The strips were removed, wiped clean, and then dried in a vacuum oven at 50 °C under nitrogen purge. These strips containing PPh 4 I by diffusion were then exposed to heat and oxygen as described above.
• Table 2 shows that after heat exposure the polyketone polymer with iodide was again an insoluble swollen gel (20% sol) in HFIPA, while the sample without iodide treatment was completely soluble and displayed a loss in molecular weight.
• This example shows that iodide can be added after part fabrication but before heat and oxygen is applied to yield a cross-linked polyketone.

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• 1994
  • 1994-11-17 CA CA 2176937 patent/CA2176937A1/en not_active Abandoned
  • 1994-11-17 CN CN94194209A patent/CN1041425C/zh not_active Expired - Fee Related
  • 1994-11-17 WO PCT/EP1994/003851 patent/WO1995014056A1/en not_active Application Discontinuation
  • 1994-11-17 AU AU10663/95A patent/AU683515B2/en not_active Ceased
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