Patent Application
20080027209
The present invention may be understood more readily by reference to the following detailed description of the invention.
It must also be noted that, as used in the specification and the appended claims, the singular forms “a,” “an” and “the” include plural referents unless the context clearly dictates otherwise. For example, reference to processing or making a “polymer,” a “preform,” “article,” “container,” or “bottle” is intended to include the processing or making of a plurality of polymers, preforms, articles, containers or bottles.
References to a composition containing “an” ingredient or “a” polymer is intended to include other ingredients or other polymers, respectively, in addition to the one named.
By “comprising” or “containing” or “having” is meant that at least the named compound, element, particle, or method step etc. must be present in the composition or article or method, but does not exclude the presence of other compounds, catalysts, materials, particles, method steps, etc., even if the other such compounds, material, particles, method steps etc. have the same function as what is named, unless expressly excluded in the claims.
It is also to be understood that the mention of one or more method steps does not preclude the presence of additional method steps before or after the combined recited steps or intervening method steps between those steps expressly identified. Moreover, the lettering of process steps is a convenient means for identifying discrete activities or steps, and unless otherwise specified, recited process steps can be arranged in any sequence.
Expressing a range includes all integers and fractions thereof within the range. Expressing a temperature or a temperature range in a process, or of a reaction mixture, or of a melt or applied to a melt, or of a polymer or applied to a polymer means in all cases that the limitation is satisfied if either the applied temperature, the actual temperature of the melt or polymer, or both are at the specified temperature or within the specified range.
The word “composition” means that each listed ingredient is present in the composition, and does not imply that any ingredient in the composition is unbound or unreacted. The composition may be solid or liquid. The stated ingredients in the composition may be bound, unbound, reacted, unreacted, and unless otherwise specified, in any oxidation state. For example, specifying the presence of “aluminum” or “Al” or “lithium” or “Li” means the atoms of aluminum or lithium, respectively, and does not imply that they occupy any oxidation state, any morphological state, any structural state, or any chemical state, whether as added to or as present in the solution, polymer or composition of matter, unless such states are expressly stated.
As used herein, the term “aluminum” or any other metal such as an alkaline earth metal or alkali (e.g. lithium, sodium, potassium) means the atom and does not imply any oxidation state or chemical state. Likewise, any of these terms used in conjunction with “metal” means the atom and does not imply any oxidation state or its chemical state. Aluminum, used alone or in conjunction with the word “metal” or an alkaline earth metal or alkali metal may be in any chemical state as a salt or chelate or complex or elemental, and in any oxidation state, unless otherwise expressly stated as having a particular oxidation state. The word “elemental,” however, means a zero oxidation state.
The reported amount of a metal (e.g. ppm) is based on the amount of the metal atom present in the solution, polymer, or article and not the amount of the compound or salt, unless expressly stated as the amount of the compound or salt.
The It.V. values described throughout this description are set forth in dL/g units as calculated from the inherent viscosity measured at 25° C. in 60% phenol and 40% 1,1,2,2-tetrachloroethane by weight. Polymer samples are dissolved in the solvent at a concentration of 0.25 g/50 mL. The viscosity of the polymer solutions is determined using a Viscotek Modified Differential Viscometer. A description of the operating principle of the differential viscometers can be found in ASTM D 5225. The inherent viscosity is calculated from the measured solution viscosity. The following equations describe such solution viscosity measurements and subsequent calculations to Ih.V. and from Ih.V. to It.V:
ηinh=[ln(ts/to)]/C
The intrinsic viscosity is the limiting value at infinite dilution of the specific viscosity of a polymer. It is defined by the following equation:
Instrument calibration involves triplicate testing of a standard reference material and then applying appropriate mathematical equations to produce the “accepted” Ih.V. values. The three values used for calibration shall be within a range of 0.010; if not, correct problems and repeat testing of standard until three consecutive results within this range are obtained.
The uncorrected inherent viscosity (ηinh) of each sample is calculated from the Viscotek Model Y501 Relative Viscometer using the following equation:
ηinh=[ln(P2/KP1)]/C
The corrected Ih.V., based on calibration with standard reference materials, is calculated as follows:
Corrected Ih.V.=Calculated Ih.V.×Calibration Factor
The intrinsic viscosity (It.V. or ηint) may be estimated using the Billmeyer equation as follows:
ηint=0.5 [e0.5×Corrected Ih.V.−1]+(0.75×Corrected Ih.V.)
The reference for estimating intrinsic viscosity (Billmeyer relationship) is J. Polymer Sci., 4, pp. 83-86 (1949).
Alternatively, the It.V. can be measured using the above solvents and concentrations measured according to ASTM D 5225-98 using a differential viscometer to measure IV.
The weight of alkaline earth metal or alkali can be measured or calculated upon addition to the melt phase or by analytical techniques for detecting the amount in the finished polymer or article. Suitable detection methods for the presence of alkali metals or alkaline earth metals include inductively coupled plasma optical emission spectroscopy (ICP-OES). The concentration of an alkaline earth metal or an alkali metal or aluminum or phosphorus or any other element or metal is reported as the parts per million of metal atoms based on the weight of the polymer.
Now there is provided a composition obtained by combining:
The composition contains aluminum. The polyester polymers made with the compositions also contain aluminum. The presence of aluminum in the polyester polymer may be detected through any suitable analytical technique regardless of the oxidation state of the aluminum. Suitable detection methods for the presence of aluminum include inductively coupled plasma optical emission spectroscopy (ICP-OES). The concentration of aluminum is reported as the parts per million of metal atoms based on the weight of the polymer.
Reporting the concentration of aluminum or alkaline earth metal or alkali metals means the concentration of these atoms in the polymer, not the concentration of the metal compounds used to make the composition.
In the preparation of the composition, aluminum may be added as a compound (which includes a salt or a complex), or as an elemental metal provided that it is ultimately active as a catalyst in the polycondensation phase either alone or in combination with the alkali metal or alkaline earth metal atoms or compounds.
In one aspect of the invention, aluminum compounds with at least one organic substituent, or two, or three, are used in the preparation of the composition. Illustrative examples of aluminum compounds suitable as catalysts include those of the formula:
Al[OR]a[OR′]b[OR″]c[R′″]d
wherein R, R′, R″ are independently an alkyl group, aryl group, acyl group or hydrogen, R′″ is an anionic group, and a, b, c, d are independently 0 or positive integers, and a+b+c+d is not greater than 3 and preferably equals 3.
Aluminum compounds having catalytic activity include those which are capable of increasing the reaction rate of a polymerization reaction, in particular a condensation reaction such a those used to make polyester polymers (which can be measured as a reduction in residence time to reach a target It.V., or an increase in It.V. over time such as an increase of at least 0.1 dL/g over 1 hour). The particular aluminum compounds chosen are preferably those which are effective to increase the It.V. of the reaction melt by at least 0.2 dL/g within 1 hour (suitably when measured from a starting point of 0.2 to 0.4 dL/g after 1 hour at 280° C. and 0.8 mm Hg with adequate agitation or after 1 hour at any desired set of operating conditions, and using the concentration desired for actual operations).
The specific type of aluminum compounds employed are desirably those that do not readily soluble in ethylene glycol. The types of aluminum compounds that are not readily soluble or insoluble will, when mixed with ethylene glycol at a concentration of 3000 ppm, precipitate within 2 days at ambient conditions without agitation. While other aluminum compounds that are readily soluble in ethylene glycol can be employed and are within the scope of the invention, they are often expensive or not commercially available. Thus, the invention provides the flexibility of making solutions with a wide ranging choice of aluminum compounds, even those which are difficult to dissolve or are insoluble in ethylene glycol at ambient conditions. Suitable examples of aluminum compounds include the carboxylic acid salts of aluminum such as aluminum acetate, aluminum benzoate, aluminum lactate, aluminum laurate, aluminum stearate, aluminum alcoholates such as aluminum ethylate, aluminum isopropylate, aluminum tri n-butyrate, aluminum isopropoxide, aluminum tri-tert-butyrate, mono-sec-butoxyaluminum diisopropylate, and aluminum chelates in which the alkoxy group of an aluminum alcoholate is partially or wholly substituted by a chelating agents such as an alkyl acetoacetate or acetylacetone such as ethyl acetoacetate aluminum diisopropylate, aluminum tris(ethyl acetate), alkyl acetoacetate aluminum diisopropylate, aluminum monoacetylacetate bis(ethyl acetoacetate), aluminum tris(acetyl acetate), aluminum acetylacetonate.
The effects of the invention are particularly noticeable among the difficult to dissolve or insoluble aluminum compounds in ethylene glycol. Examples of these compounds include basic carboxylic acid salts of aluminum and aluminum alcoholates such as aluminum acetate, aluminum benzoate, aluminum laurate, aluminum stearate, aluminum alcoholates such as aluminum ethylate, aluminum isopropylate, aluminum tri n-butyrate, aluminum isopropoxide, aluminum tri-tert-butyrate, and mono-sec-butoxyaluminum diisopropylate. In one aspect, the aluminum compound comprises aluminum acetate, aluminum diacetate, and aluminum isoproxide, and especially aluminum isopropoxide.
An amount of aluminum atoms, in combination with M, are employed to effect polycondensation once added to the melt phase polymerization process. Suitable amounts of aluminum atoms present in the polymer generally range from at least 3 ppm, or at least 5 ppm, or at least 7 ppm, or at least 10 ppm, or at least 15 ppm, or at least 20 ppm, or at least 30 ppm, and up to about 150 ppm, or up to about 100 ppm, or up to about 75 ppm, or up to about 60 ppm, or up to 30 ppm, or up to 20 ppm, or up to 15 ppm aluminum atoms based on the weight of the polymer. The preferred range of aluminum loading in the polyester polymer is, and the amount of aluminum atoms present in the composition fed to a melt phase polymerization reactor is effective to provide in the polymer, 5 ppm to 60 ppm, with the most preferred amount on a calculated basis ranging from 7 to 20 ppm Al based on the weight of the polymer.
Of course, the solution composition may and usually will contain a much higher concentration of the metals than present in the polyester polymer. The composition is fed or metered to the melt phase at a rate corresponding to the desired amount of metal present in the polyester polymer. The composition may contain from 1000 ppm, or at least 2000 ppm, or greater than 3000 ppm, or at least 3500 ppm, or at least 4000 ppm, or at least 5000 ppm, or at least 1 wt. %. The maximum amount of aluminum used is up to its solubility limit in a given solvent mix at ambient conditions. High concentrations of aluminum are desirable so that the amount of solvent fed to the melt phase process is reduced and/or higher loadings of aluminum can be fed to the melt phase process for making the polyester polymer at a given flow rate in order to increase the polycondensation reaction rate and thereby lower the polymerization time and increase throughput.
In one embodiment, there is provided a catalyst solution containing at least 3000 ppm aluminum, or at least 3500 ppm aluminum, or at least 4000 ppm aluminum, or at least 10,000 ppm, and may contain up to 10 wt. % or up to 5 wt. % or up to 3 wt. % or up to 2 wt. % aluminum.
The alkali may be added as a metal compound or an organometallic compound. The alkali metals and alkaline earth metals include the metals in Group IA and Group IIA or the periodic table, including but not limited to Li, Na, K, Rb, Cs, Mg, Ca, Sr, and preferably Li, Na or K. If rapid rates are the primary concern, Li or Na are generally preferred. If color is the primary concern, Na is most preferred. The metals may be added to the melt phase as metal compounds (which includes a complex or a salt) having counterions, among which the preferred ones are hydroxides, carbonates, and carboxylic acids.
The amount of alkaline earth metal or alkali, in combination with Al, is effective to increase the molecular weight of the polymer melt. The amount by weight will vary widely depending upon the molecular weight of the metal. The amount of the alkaline earth metal or alkali metal in the composition may vary between at least 100 ppm, or at least 250 ppm, or at least 500 ppm, or at least 700 ppm, or at least 780 ppm, or at least 1000 ppm, or at least 2000 ppm, or at least 2460 ppm, or at least 3000 ppm, or at least 5000 ppm, or at least 1 wt. %, or at least 2 wt. %, and up to about 30 wt. %, or up to about 20 wt. %, or up to 15 wt. %, or up to 10 wt. %, or up to 5 wt. %, or up to 2 wt. %, or up to 1 wt. %, or up to 5000 ppm, based on the weight of the solution.
The amount of alkaline earth metal or alkali metal fed to the melt phase polymerization process is effective to produce a polyester polymer composition containing, and the polyester polymer composition contains, from at least 1 ppm, or at least 2 ppm, or at least 3 ppm, or at least 4 ppm, or at least 5 ppm, and up to about 60 ppm, or up to about 50 ppm, or up to about 30 ppm, or up to about 20 ppm, or up to about 15 ppm, alkaline earth metal or alkali metal on a calculated basis and based on the weight of the polyester polymer composition. The particular amount of the alkaline earth metal or alkali metal in the polyester polymer again will vary depending upon the molecular weight of the metal.
The molar ratio of the alkaline earth metal or alkali:aluminum (M:Al) is desirably at least 0.2:1, or at least 0.5:1, or at least 0.75:1, or at least 0.9:1, or at least 1:1, and up to 10:1, or up to 2.5:1, or up to 2:1, or up to 1.8:1, or up to 1.6:1, or up to 1.5:1, or up to 1.4:1, or up to 1.25:1, or up to 1.1:1. More examples of suitable ranges include 0.75:1 to 2:1, or 0.75:1 to 1.8:1, or 0.9:1 to 1.5:1, or 0.9:1 to 1.25:1. It is desirable to provide a large number of Al atoms to increase the catalytic activity of the catalyst system. Ethylene glycol has been a common carrier for a wide variety of solutions and/or dispersions since it is generally a reactant in the polymerization process for making a polyester polymer or is highly compatible with the melt. Even though many forms of aluminum are very difficult to remain soluble in ethylene glycol, it is now possible, however, using the organic hydroxyacids described in the invention, to provide a solution which has a lower tendency to precipitate even at higher levels of aluminum and/or at low temperatures and/or at molar ratios of M:Al approaching 1:1, using only small molar quantities of the solubilizing aid, hydroxyacid compounds.
Much more soluble catalysts having molar ratios of M:Al approaching 1:1 are obtainable using the organic hydroxyacids described below, whereas stable solutions employing molar ratios of M:Al approaching 1:1 in ethylene glycol as the sole solvent are not obtainable. In this embodiment, a more soluble catalyst is obtainable at molar ratios of M:Al within a range of 0.5:1 to 1.8:1, or 0.75:1 to 1.5:1, or 0.9:1 to 1.25:1, or 0.9:1 to 1.1:1. We have found that solutions of ethylene glycol tend to be more stable as the molar ratio of M:Al increases to 3:1 and beyond, but at molar ratios approaching 1:1, precipitates readily form upon cooling the solution to ambient conditions. By contrast, the addition of organic hydroxyacids, such as lactic acid, improves the solubility and stability of these catalysts with lower M:Al mole ratios even at low molar quantities of the hydroxyacid.
In another embodiment, the molar ratio of M:hydroxyacid compounds is at least 0.80:1, or at least 0.90:1, or at least 0.95:1, or at least 1:1, or at least 1.2:1, or at least 1.5:1. The upper amount may be as large as desired. Generally, the amount will not exceed 10:1, or not exceed 5:1, or not exceed 3:1. With higher molar ratios of M:hydroxyacid, the amount of hydroxyacid compounds are minimal. The amount of hydroxyacid, however, should be sufficient to improve the solubility of the catalyst system in ethylene glycol as discussed further below.
The organic hydroxyacids employed in the invention keep the alkaline earth metal or alkali metal and aluminum metal combinations more soluble particularly in the temperature range of 20-90° C. In one embodiment, any one of the compositions described herein remain in solution at ambient conditions (25° C. to 35° C. and about 1 atmosphere without agitation) over a period of at least one (1) week.
The organic hydroxyacid compounds have at least one hydroxyl group and at least one —COOH group and have at least 3 carbon atoms and less than three carboxylic acid groups when the hydroxyacid compound has 8 or less carbon atoms (counting the carboxylic acid carbons). The organic hydroxyacid compound is a type of compound which enhances the solubility of the catalyst system in ethylene glycol, especially at molar ratios of M:Al less than 3:1, or less than 2:1, or less than 1.5:1. Preferably, the hydroxyacid compounds have a hydroxyl group and a carboxylic acid group bonded in the alpha or beta position relative to each other on aliphatic compounds and are separated by no more than 3 carbons on aromatic or alicyclic compounds. In one embodiment, the hydroxy acid compound is an aliphatic compound having a hydroxyl group and a carboxylic acid group covalently bonded to the same carbon atom (alpha position with respect to each other). In another embodiment, the aliphatic hydroxyacid compound has a hydroxyl group bonded to a carbon atom adjacent to a carbon atom bonded to a carboxylic acid group (beta position with respect to each other). On alicyclic or aromatic compounds, the hydroxyl group is bonded to a carbon which is directly bonded to a carbon bonded to a carboxylic acid group (separation by 2 carbon atoms and considered beta) or indirectly through a third carbon atom (separation by 3 carbon atoms). Preferably, the organic hydroxyacid compounds are alpha- or beta-hydroxycarboxylic acids, where the hydroxyl group is bonded to the same carbon bonded to a —COOH group (alpha) or bonded to a carbon adjacent to the carbon bonded to a —COOH group (beta). The organic hydroxyacid compounds have at least 3 carbon atoms and up to 48 carbon atoms, or up to 24 carbon atoms, or up to 14 carbon atoms, or up to 10 carbon atoms, or up to 8 carbon atoms, or up to 6 carbon atoms, or up to 4 carbon atoms. However, the hydroxyacid compound has only or two carboxylic acid groups when the hydroxyacid compound has 8 or less carbon atoms. It is believed that the hydroxyl group and the carboxylic acid group bind to the same aluminum center on the catalyst. Short chain aliphatic molecules having 8 or less carbon atoms preferably have an alpha carbon or beta carbon (hydroxyl and carboxyl bonded to the same carbon atom or having one carbon between them) and one or two carboxylic acid groups. For example, citric acid, a short chain hydroxyacid compound having 6 carbon atoms and three carboxylic acid groups, does not enhance the solubility of the catalysts in ethylene glycol. Further, hydroxyacid compounds having only two carbon atoms (counting the carboxylic acid carbons) do not provide a noticeable benefit. The hydroxyacid compounds may be mono-carboxylic acids, di-carboxylic acids, or tri-carboxylic acids (when the number of carbon atoms exceeds 8), desirably mono-carboxylic acids and dicarboxylic acids. The hydroxyacids may have one or more aromatic groups, alicyclic groups, or may be aliphatic.
Specific examples of useful organic hydroxyacid compounds are lactic acid, tartaric acid, mandelic acid and salicylic acid. Other examples believed to provide enhance solubility include 1-carboxy-2-hydroxynapthalene, 1-hydroxy-2-carboxynaphthalene, 2-hydroxyisobutyric acid, 3-hydroxyisobutyric acid, 2-hydroxybutyric acid, 3-hydroxybutyric acid, malic acid, 2-hydroxycyclohexanecarboxylic acid, 2-hydroxyisovaleric acid, 2-hydroxyvaleric acid, and 3-phenyllactic acid.
Functional groups other than and in addition to the polyhydroxyl groups may be present on the solvent compound. However, it is desirable that the hydroxyl groups and carboxylic acid groups are the only reactive functionalities on the solvent compound.
The organic hydroxyacids are mixed as additives in catalyst compositions containing ethylene glycol to increase the solubility of the catalyst system in ethylene glycol to a desired level relative to the solubility of the same catalyst system in ethylene glycol without the hydroxyacid compounds. The amount of organic hydroxyacid solvent is sufficient to solubilize the aluminum and alkaline earth metal or alkali metals in ethylene glycol for the desired amount of time, but at least for one (1) week, and desirably for at least one (1) week at ambient conditions. The organic hydroxyacid solvent is a solubilizing aid in ethylene glycol containing catalyst compositions. Other diluents, solvents, or liquid carriers may be combined with the hydroxyacid solubilizing agent if desired. The amount of organic hydroxyacid solvent generally ranges from at least 0.01 wt %, or at least 0.1 wt. %, or at least 0.5 wt. %, or at least 1 wt. %, and up to about 5 wt. %, or up to about 4 wt. %, or up to about 3 wt. %, or up to 2 wt. %, based on the weight of the solution. The catalyst solution of the invention contains a minimum amount of ethylene glycol relative to the amount of aluminum employed. The catalyst solution of the invention contains a molar ratio of ethylene glycol (EG) to aluminum of at least 35:1, or at least 40:1, or at least 50:1, or at least 75:1, or at least 100:1, or at least 125:1. The amount of ethylene glycol can be increased as desired up to the point where the catalyst composition is no longer soluble and requires some amount of the hydroxyacid compounds. By using a large molar excess of ethylene glycol, minimal amounts of the hydroxyacid can be used, thereby reducing costs, and reducing potential alternations in the properties of the polymer and reducing the quantity that is removed from the polymer melt during polycondensation or form the vacuum systems.
The molar ratio of M:Al:hydroxyacid desirably range from 0.2:1:0.2 to 10:1:5. In another embodiment, the molar amounts range from 0.2:1:0.5 to 5:1:3. In another embodiment, the molar amounts range from 0.2:1:0.5 to 3:1:2.
The solution is prepared by combining ethylene glycol, the alkaline earth metal or alkali salts, and the aluminum compounds, preferably a tridentate aluminum compound, adding the organic hydroxyacid solvent, and stirring the mixture at a temperature ranging from 20° C. to 150° C., or at 80° C. to 140° C. To determine whether a given composition is a solution, a measurement of the composition can be taken to determine whether visible to the naked eye any precipitation occurs by allowing the solution to stand still over a period of at least one (1) week, and in the preferably embodiments, at ambient conditions In another embodiment, the solubility of (i) and (ii) in the solvent at the given concentrations in a particular composition is sufficiently high such than no precipitation is visible to the naked eye when the solution is allowed to stand still over a period of period of at least two (2) weeks, or at least three (3) weeks, or at least four (4) weeks at ambient conditions. There is usually a slight haze to the catalyst preparations. The amount of the haze is often related to the amount of water that is contained in the ethylene glycol or the aluminum compound.
One or any combination of benefits and features are obtainable by the solutions of the invention:
The aluminum is typically combined with (i) and (iii) in the form of a salt or compound, as is M, as noted above.
The polyester polymer produced in the melt phase may contain phosphorus atoms. Phosphorus may be added late in the melt phase polymerization process to deactivate or stabilize the catalyst system, thereby reducing the haze level of the polymer, bottle preforms, and bottles made thereby, even at high catalyst loadings. The polyester polymer may contain phosphorus atoms in an amount ranging from 3 ppm to 500 ppm, based on the weight of the polymer composition. The amount of phosphorus is desirably at a mole ratio of P:M (all metals of aluminum and alkaline earth metals and alkali metals) within a range of 0.2:1 to 3:1. Typical amounts of phosphorus atoms will be at least 3 ppm, or at least 5 ppm, or at least 10 ppm, or at least 50 ppm, or at least 100 ppm, and up to 500 ppm, or up to 200 ppm, or up to 100 ppm, or up to 50 ppm, or up to 30 ppm, or up to 15 ppm. The solution haze values of these polymers can be as low as 30 ntu or less, or 20 ntu or less, or 15 ntu or less, or 10 ntu or less. The relative reduction of haze by addition of phosphorus is as large as 40% or more, or 50% or more, or 60% or more, relative to the same polymer made without phosphorus.
Other catalyst metals may be present if desired. For example, Mn, Zn, Sb, Co, Ti, and Ge catalysts may be used in conjunction with aluminum and alkaline earth metals or alkali catalysts. Preferably, the polyester polymer is made without the addition of cobalt to the melt phase reaction since organic toners are preferred. Titanium catalysts can be used. The titanium catalysts are those compounds added in amounts which increase the It.V. of polyester melt by at least 0.3 dL/g if not deactivated. The amount of titanium catalyst, if used, generally ranges from 2 ppm to 15 ppm, or up to 10 ppm, based on the weight of the polymer. Antimony catalysts can also be used in combination with the catalyst system of the invention. The amount of antimony can range from 20 ppm to 250 ppm. Due to M generation concerns, the amount of antimony is preferred to be no greater than 125 ppm, based on the weight of the polymer, and preferably there is provided a polyester polymer which does not contain any antimony added to its manufacture in the melt phase.
In one embodiment, the polyester polymer contains aluminum, alkaline earth metal or alkali metals, and does not contain any antimony catalyst in catalytic quantities, or does not contain any cobalt catalyst in catalytic quantities, or does not contain any titanium catalyst in catalytic quantities, or does not contain any germanium catalyst in catalytic quantities, or does not contain any combination of Ti, Co, Sb, or Ge based catalysts in catalytic quantities, or does not contain any of the aforementioned catalyst metals (other than Al and alkaline earth metal or alkali metals) added to the polymer during its manufacture in the melt phase, or does not contain any catalyst metals other than aluminum and an alkaline earth metal or alkali. A catalyst metal is said to have catalytic activity if it increases the reaction rate or increases the It.V. of the melt by at least 0.1 dL/g from a starting point of 0.2 to 0.4 dL/g after 1 hour at 280° C. and 0.8 mm Hg. It is to be recognized, however, that one or more of metals such as cobalt or manganese will most likely be present at low levels in the melt because they come as impurities with the terephthalic acid composition made from a metal-catalyzed, liquid-phase oxidation process. Metal impurities present in the raw material supply to the melt phase process are not considered to be metals added to the melt phase process and they are not present in any event in catalytically effective quantities.
The “polyester polymer” is any thermoplastic polyester polymer. Polyester thermoplastic polymers of the invention are distinguishable from liquid crystal polymers and thermosetting polymers in that thermoplastic polymers have no appreciable ordered structure while in the liquid (melt) phase, they can be remelted and reshaped into a molded article, and liquid crystal polymers and thermosetting polymers are unsuitable for the intended applications such as packaging or stretching in a mold to make a container.
The polyester polymer is desirably a random polymer such that the monomer units in the polymer chain are randomly arranged rather than arranged in a block fashion. The polyester polymer contains repeating alkylene aryl units, such as alkylene terephthalate or alkylene naphthalate repeat units in the polymer chain. More specific examples of these repeating units include ethylene terephthalate, ethylene naphthalate, and trimethylene terephthalate.
In another embodiment, polyester polymers comprise:
More than one compound containing hydroxyl group(s) or derivatives thereof can become part of the polyester polymer product(s). All the compounds that enter the process containing hydroxyl group(s) or derivatives thereof that become part of said polyester product(s) comprise the hydroxyl component. The mole % of all the compounds containing hydroxyl group(s) or derivatives thereof that become part of said polyester product(s) add up to 100. The “residues” of hydroxyl functional compound(s) or derivatives thereof that become part of said polyester product refers to the portion of said compound(s) which remains in said polyester product after said compound(s) is condensed with a compound(s) containing carboxylic acid group(s) or derivative(s) thereof and further polycondensed to form polyester polymer chains of varying length.
The mole % of the hydroxyl residues and carboxylic acid residues in the product(s) can be determined by proton NMR.
In another preferred embodiment, the polyester polymer comprises:
The reaction of the carboxylic acid component with the hydroxyl component during the preparation of the polyester polymer is not restricted to the stated mole percentages since one may utilize a large excess of the hydroxyl component if desired, e.g. on the order of up to 200 mole % relative to the 100 mole % of carboxylic acid component used. The polyester polymer made by the reaction will, however, contain the stated amounts of aromatic dicarboxylic acid residues and ethylene glycol residues.
Derivates of terephthalic acid and naphthalane dicarboxylic acid include C1-C4 dialkylterephthalates and C1-C4 dialkylnaphthalates, such as dimethylterephthalate and dimethylnaphthalate.
Modifiers can be present in amount of up to 40 mole %, or up to 20 mole %, or up to 10 mole %, or up to 8 mole %, or up to 4 mole %, based on the total moles of their respective component in the polymer. Mono, tri and higher functional modifiers are preferably present in amounts of only up to about 8 mole %, or up to 4 mole %.
In addition to a diacid component of terephthalic acid, derivates of terephthalic acid, naphthalene-2,6-dicarboxylic acid, derivatives of naphthalene-2,6-dicarboxylic acid, or mixtures thereof, the carboxylic acid component(s) of the present polyester may include one or more additional modifier carboxylic acid compounds. Such additional modifier carboxylic acid compounds include mono-carboxylic acid compounds, dicarboxylic acid compounds, and compounds with a higher number of carboxylic acid groups. Examples include aromatic dicarboxylic acids preferably having 8 to 14 carbon atoms, aliphatic dicarboxylic acids preferably having 4 to 12 carbon atoms, or cycloaliphatic dicarboxylic acids preferably having 8 to 12 carbon atoms. More specific examples of modifier dicarboxylic acids useful as an acid component(s) are phthalic acid, isophthalic acid, naphthalene-2,6-dicarboxylic acid, cyclohexane-1,4-dicarboxylic acid, cyclohexanediacetic acid, diphenyl-4,4′-dicarboxylic acid, succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, and the like, with isophthalic acid, naphthalene-2,6-dicarboxylic acid, and cyclohexane-1,4-dicarboxylic acid being most preferable. It should be understood that use of the corresponding acid anhydrides, esters, and acid chlorides of these acids is included in the term “carboxylic acid”. It is also possible for tricarboxyl compound branching agents and compounds with a higher number of carboxylic acid groups to modify the polyester, along with monocarboxylic acid chain terminators.
In addition to a hydroxyl component comprising ethylene glycol, the hydroxyl component of the present polyester may include additional modifier polyhydroxyls, diols, or compounds with a higher number of hydroxyl groups. Examples of modifier hydroxyl compounds include cycloaliphatic diols preferably having 6 to 20 carbon atoms and/or aliphatic diols preferably having 3 to 20 carbon atoms. More specific examples of such diols include diethylene glycol; triethylene glycol; 1,4-cyclohexanedimethanol; propane-1,3-diol; butane-1,4-diol; pentane-1,5-diol; hexane-1,6-diol; 3-methylpentanediol-(2,4); 2-methyl pentanediol-(1,4); 2,2,4-trimethylpentane-diol-(1,3); 2,5-ethylhexanediol-(1,3); 2,2-diethyl propane-diol-(1,3); hexanediol-(1,3); 1,4-di-(hydroxyethoxy)-benzene; 2,2-bis-(4-hydroxycyclohexyl)-propane; 2,4-dihydroxy-1,1,3,3-tetramethyl-cyclobutane; 2,2-bis-(3-hydroxyethoxyphenyl)-propane; and 2,2-bis-(4-hydroxypropoxyphenyl)-propane.
As modifiers, the polyester polymer may preferably contain such comonomers as isophthalic acid, naphthalane dicarboxylic acid, 1,4-cyclohexanedimethanol, and diethylene glycol.
The polyester composition may include blends of polyalkylene terephthalates and/or polyalkylene naphthalates along with other thermoplastic polymers such as polycarbonate (PC) and polyamides. It is preferred that the polyester composition should comprise a majority of the polyester polymers, more preferably in an amount of at least 80 wt. %, or at least 95 wt. %, and most preferably 100 wt. %, based on the weight of all thermoplastic polymers (excluding fillers, inorganic compounds or particles, fibers, impact modifiers, or other polymers which may form a discontinuous phase). It is also preferred that the polyester polymers do not contain any fillers, fibers, or impact modifiers or other polymers which form a discontinuous phase.
In one embodiment, the composition contains less than 60 wt %, or less than 40 wt %, or less than 20 wt. %, or less than 10 wt. %, or less than 5 wt. %, or no post consumer recycle polyester polymer (“PCR”) present in the composition. In another embodiment, the composition contains PCR in an amount of greater than zero and up to 60 wt. %, or up to 40 wt. %, or up to 20 wt %, or up to 10 wt. %.
Specific examples of the phosphorus compounds mentioned above as suitable catalyst deactivators and/or stabilizers include phosphoric acid, pyrophosphoric acid, phosphorous acid, polyphosphoric acid, carboxyphosphonic acids, phosphonic acid derivatives, and each of their acidic salts and acidic esters and derivatives, including acidic phosphate esters such as phosphate mono- and di-esters and non-acidic phosphate esters (e.g. phosphate tri-esters) such as trimethyl phosphate, triethyl phosphate, tributyl phosphate, tributoxyethyl phosphate, tris(2-ethylhexyl) phosphate, oligomeric phosphate tri-esters, trioctyl phosphate, triphenyl phosphate, tritolyl phosphate, (tris)ethylene glycol phosphate, triethyl phosphonoacetate, dimethyl methyl phosphonate, tetraisopropyl methylenediphosphonate, mono-, di-, and tri-esters of phosphoric acid with ethylene glycol, diethylene glycol, or 2-ethylhexanol, or mixtures of each. Other examples include distearylpentaerythritol diphosphite, mono- and di-hydrogen phosphate compounds, phosphite compounds, certain inorganic phosphorus compounds that are preferably soluble in the polymer melt, poly(ethylene)hydrogen phosphate, silyl phosphates; phosphorus compounds used in combinations with hydroxy- or amino-substituted carboxylic acids, such as methyl salicylate, maleic acid, glycine, or dibutyl tartrate; each useful for inactivating metal catalyst residues. Haze in solutions of particles or in molded parts is one indication of lack of solubility. Soluble additives are more likely to deactivate/stabilize the catalyst system.
Other phosphorus compounds which may be added include the amine salts of phosphorus-containing acids. The amines may be cyclic or acyclic, may be monomeric, oligomeric, or polymeric, and should be selected so as to minimize haze and/or solubility when the latter are issues. The organic constituents of the amine may in principle be any organic group. Ammonia and related compounds like ammonium hydroxide are suitable.
To minimize It.V. loss if large quantities of phosphorus are added, or to further minimize the potential It.V. loss even if moderate or optimal quantities of phosphorus are added, it is desirable to add the phosphorus compound neat, that is without further dilution, such as in the case of 85% or more phosphoric acid. If a carrier is used, it is preferred that that the carrier is nonreactive, that is, does not break the polymer chain nor increase AA generation rates. Water, alcohols, glycols and lower molecular weight PET are known to break the polymer chain. Once the minimum amount of the phosphorus compound and the associated It.V. loss are known, the melt-phase process can be carried out such that the It.V, made before deactivation/stabilization, is higher by the amount of It.V. loss expected so that the target ItV. can be achieved.
The melt phase reaction proceeds in a batch, semi-batch, or continuous mode. Preferably, the process of the invention is continuous.
The catalyst solution may be added after at least 50%, or at least 90% completion of esterification, or between the esterification zone and polycondensation zone, or at a point when polycondensation starts, or during prepolymerization. In one embodiment, the catalyst solution is added between the esterification zone and inception of or during polycondensation or at the inception of or during prepolymerization.
In another embodiment, the catalyst solution is added at any point to upon or after completion of esterification (at least 90% conversion) up to when the It.V. of the polyester melt reaches 0.3 dL/g, or no later than when the It.V. of the melt reaches 0.2 dL/g, and more preferably to the oligomer mixture exiting the esterification zone or prior to commencing or at the start of polycondensation.
If the molar ratio of the catalyst solution is not the molar ratio of M:Al desired in the melt phase to polymerize the polyester melt, the present invention allows one the flexibility of feeding to the melt phase a stream of the stable catalyst solution of the invention while also feeding to the melt phase process a separate stream of alkaline earth metal or alkali M. In this way, one obtains the benefit of employing a stable catalyst solution having a molar ratio of M:Al ranging from 0.5:1 to 1.5:1 to minimize yellow color body formation in the polymer melt, while retaining the flexibility of increasing the molar ratio of M:Al on a manufacturing line as high as desired to increase the polycondensation rate and reduce residence time where color body formation in the polymer is not or paramount importance, thereby obtaining a variety of polymers having differing characteristics on the same melt phase polymerization line. Thus, the catalyst solution of the invention can be fed at any point in the melt phase process as described above, while simultaneously feeding a separate stream of alkaline earth metal or alkali M earlier or later or at the same feed point as the catalyst solution feed point, preferably earlier or at the same point, to adjust the desired M:Al molar ratio as needed. For example, a stream of the alkaline earth metal or alkali M can be fed to the esterification zone and before 90% conversion, or before 70% conversion, or before 50% conversion, or before 40% conversion, or before 20% conversion, while the catalyst solution can be fed at a point between 90% conversion in esterification and the polycondensation zone when the It.V. of the melt is less than 0.3 dL/g. Both feeds can occur simultaneously in a continuous process for making the polyester polymer. The feed stream of alkaline earth metal or alkali metals can be the same or different alkaline earth metals or alkali metals employed in the catalyst solution. For example, M may be Li in the catalyst solution containing Al, and M may be Na or K in the split feed stream. This allows even further flexibility in using two or more different alkaline earth metal or alkali metal M in the same melt phase polymerization line or process if desired
In one embodiment where the phosphorus compound is added to a melt phase polymerization process, the catalyst stabilizer is added to the polyester melt late during the course of polycondensation and before solidification. The deactivator is added to the polyester melt late in the course of the polycondensation reaction when one or more of the following conditions are satisfied or thereafter and before solidification of the polyester melt:
In one embodiment, the deactivator is added to the polyester melt after the polyester melt obtains an It.V. of at least 0.50 dL/g, or at least 0.55 dL/g, or at least 0.60 dL/g, or at least 0.65 dL/g, or at least 0.68 dL/g, or at least 0.70 dL/g, or at least 0.72 dL/g or at least 0.76 dL/g, or at least 0.78 dL/g, and most preferably, regardless of when the deactivator is added, the resulting polymer exiting the melt phase manufacture has an It.V. of at least 0.68 dl/g.
In another embodiment, the deactivator is added to the polyester melt during or after releasing the vacuum from the polyester melt undergoing polycondensation reactions, or after bringing the pressure in a polycondensation zone or reactor to a level of 300 mm Hg or greater, or 450 mm Hg or greater, or 600 mm Hg or greater, or to atmospheric pressure or greater, and preferably before the polyester melt is solidified.
In another embodiment, the deactivator is added at a location near or at the end of a final reactor or between the final reactor and before a cutter. For example, the deactivator is added to the last polycondensation reactor at a location proximal to the outlet of the last polycondensation reactor, or to a pipe connecting directly or indirectly the last polycondensation reactor and a gear pump or extruder providing the motive force to drive the melt through a die plate for cutting wherein said pipe is directed back to or proximal to the outlet or the bottom of the last polycondensation reactor, or to a pipe inlet to the last polycondensation reactor.
In yet another embodiment, the deactivator is added to the polyester melt following at least 85%, or at least 90%, or at least 95%, or at least 98%, or about 100% of the polycondensation time. The polycondensation time is measure as the time elapsed between the start of polycondensation zone to the exit of the polyester melt from the last polycondensation reactor.
In a further embodiment, the deactivator is added to the polyester melt when the It.V. of the polyester melt is within 0.10 dL/g, or within 0.05 dl/g, or within 0.030 dL/g, or within 0.02 of the It.V. obtained upon solidification.
In yet another embodiment, the deactivator is added to the polyester melt at a point within 20 minutes, or within 10 minutes or less, or 5 minutes or less, or 3 minutes or less of solidifying the polyester melt. The solidification of the polyester melt typically occurs when the melt is forced through a die plate into a water bath and cut into pellets, or in a melt-to-mold process when the melt is injection molded into a molded article.
In yet a more preferred embodiment, each of the embodiments identified herein occurs in a continuous manufacturing process where the throughput of the melt phase process is at least 1 ton/day, or at least 50 tons/day, or at least 100 tons/day, or at least 200 tons/day, or at least 300 tons/day, or at least 400 tons/day, or at least 500 tons/day of polyester polymer in a steady state operation.
The reaction time of the melt from an It.V. of 0.40 dL/g through and up to an It.V. in the range of at least 0.68 dL/g to 0.94 dL/g is 150 minutes or less, or 120 minutes or less, or 90 minutes or less, or 50 minutes or less. The target It.V. is preferably between 0.84 and 0.94 d/g prior to deactivation/stabilization, the vacuum applied is preferably between 0.5 and 1.0 torr, and temperature is preferably between 275° C. to 285° C.
Stabilizing or deactivating the catalyst late or near the end of a melt phase process can result in polyester particles that, in the absence of acetaldehyde (AA) scavengers, generate less AA during subsequent melt processing. With late addition of a phosphorus compound, Al/alkaline earth metal or alkali catalyst systems can produce polyester polymers with lower AA generation rates than polyester polymers made without the presence of a catalyst deactivator or polyesters made with conventional antimony catalysts that are similarly deactivated late with a phosphorus compound. With late addition of a phosphorus compound to the polyester melt catalyzed with an aluminum/alkaline earth metal or alkali system, it is now possible to obtain a polyester polymer having free M levels and an M generation rate low enough for use in water bottle applications without the need to add AA scavengers or other AA lowering additives. Moreover, this type of polymer having both low free AA levels and low AA generation rates without the presence of an AA lowering additive can be obtained to a high It.V. (at least 0.68 dL/g, or at least 0.70 dL/g, or at least 0.72 dL/g, or at least 0.74 dL/g, or at least 0.76 dL/g, or at least 0.80 dL/g, or at least 0.84 It.V.) in the melt phase without the necessity for polymerizing the polymer in the solid-state. Some catalyst combinations, some phosphorus levels in PET from late addition, and some water bottle specifications may necessitate a brief AA stripping treatment to lower free AA below 2 ppm prior to beginning the injection molding process.
The polyester polymer compositions made with the composition, when partially crystallized to a degree of crystallinity of at least 20%, have an L* of at least 70, or at least 73, or at least 76, or at least 79, and an It.V. of at least 0.70 dL/g, or at least 0.72 dL/g, or at least 0.76 dL/g obtained from the melt phase.
The particles of the invention are directly or indirectly packaged as a bulk into shipping containers, which are then shipped to customers or distributors. It is preferred to subject the crystallized particles to any process embodiment described herein without solid state polymerizing the particles at any point prior to packaging the particles into shipping containers.
Shipping containers are containers used for shipping over land, sea or air. Examples include railcars, semi-tractor trailer containers, Gaylord boxes, ship hulls, or any other container which is used to transport finished polyester particles to a customer. Customers are typically converter entities who convert the particles into preforms or other molded articles.
The shipping containers contain a bulk of polyester polymer particles. A bulk occupies a volume of at least 3 cubic meters. In preferred embodiments, the bulk in the shipping container occupies a volume of at least 5 cubic meters, or at least 10 cubic meters.
In one embodiment, there is provided finished polyester polymer particles having an average It.V. of at least 0.68 dL/g, or 0.70 dL/g, or 0.72 dL/g, or 0.74 dL/g, or 0.76 dL/g, obtained in a melt phase polymerization and a residual acetaldehyde level of 10 ppm or less or of 5 ppm or less; wherein said particles contain aluminum in an amount of at least 3 ppm, or at least 5 ppm, or at least 10 ppm, or at least 15 ppm, or at least 20 ppm based on the weight of the polymers, and further contain the residues of a organic hydroxyacid solvent either reacted into the polyester chain, reacted as an end group on the polyester chain, or reacted on a polyester polymer by transesterification. The solvent may be reacted into the polyester chain during melt phase polymerization such that the polyester polymer contains one unit or random repeat units of the organic hydroxyacid solvent residue. Preferably, the polyester particles in the shipping container also have a degree of crystallinity of at least 20%, preferably at least 30%; and the particles also contain a nonzero level of an alkaline earth metal or alkali metal, along with a nonzero level of phosphorus. The particles are desirably contained in a shipping container. Most preferably, the particles have not been solid state polymerized. By “finished” particles is meant particles that have been subjected by the particle manufacturer to all the processing conditions needed to produce a particle ready for feeding into dryer hoppers associated with a molding machine or directly to a molding machine used for converting particles into articles, without any further processing steps performed by the particle manufacturer.
Suitable articles which are formed from the polyester polymer compositions manufactured with the composition of the invention are sheets, bottle preforms, beverage bottle preforms, and blow molded bottles made therefrom.
This invention can be further illustrated by the additional examples of embodiments thereof, although it will be understood that these examples are included merely for purposes of illustration and are not intended to limit the scope of the invention.
The compositions of the invention may exhibit haziness yet constitute solutions in which no precipitation occurs. Precipitates are deemed formed when by the eye one can observe the presence of the catalyst metal particulates settled at the bottom of the vessel.
These catalyst mixtures were prepared from lithium hydroxide monohydrate, aluminum isopropoxide, ethylene glycol, and the specified hydroxyacid in the reported amounts at approximately 125° C. for 3 hours under a positive flow of nitrogen. Essentially all the catalyst mixtures were clear when initially prepared. The catalysts were then stored at 45° C. and their solubility was observed over a two week period. The results are reported in Table 1.
PET polymers were made using the above catalyst compositions to a target Ih.V ranging from 0.75 to 0.85 dL/g. The process began with the esterification of terephthalic acid under a positive pressure at approximately 265° C. The oligomer was isolated and subjected to prepolymer and polycondensation conditions. The catalyst mixture was added at the beginning of the prepolymer stage. All polymers were made from the same batch of oligomer. The prepolymer conditions were 278° C. for 75 minutes at 30 torr and the polycondensation conditions were 278° C. and 4 torr. The polycondensation was allowed to run until the desired melt viscosity was achieved.
This application claims priority to Provisional Application No. 60/834,116 filed Jul. 28, 2006.
| Number | Date | Country | |
|---|---|---|---|
| 60834116 | Jul 2006 | US |
