WO2011116971A1

WO2011116971A1 - Blow molded container comprising branched carbonate polymer composition

Info

Publication number: WO2011116971A1
Application number: PCT/EP2011/001485
Authority: WO
Inventors: Kai-Leung L. Cheng
Original assignee: Styron Europe Gmbh
Priority date: 2010-03-24
Filing date: 2011-03-24
Publication date: 2011-09-29
Also published as: TW201144357A

Abstract

The present invention relates to an improved branched carbonate polymer composition and methods to make said composition. The branched carbonate polymer composition comprises a blend of a branched carbonate polymer component, a first linear carbonate polymer component, and a second linear carbonate polymer component, wherein the ratio of melt flow rates of the first linear carbonate polymer component to the second linear carbonate polymer component is equal to or greater than 1 to 3. The invention further relates to the containers comprising the improved branched carbonate polymer composition, and methods to manufacture said containers, preferably blow molding. Containers made from the improved branched carbonate polymer composition demonstrate an improved blend of properties, specifically improved impact resistance, clarity, and lower levels of entrapped bubbles than traditional water bottles.

Description

BLOW MOLDED CONTAINER COMPRISING BRANCHCED CARBONATE

POLYMER COMPOSITION

FIELD OF THE INVENTION

The present invention relates to an improved carbonate composition comprising a blend of branched and linear polycarbonates for use in molded containers, preferably large water bottles. The invention further relates to the containers comprising the improved branched carbonate polymer composition, and methods to manufacture said containers, preferably blow molding. Containers made from the improved branched carbonate polymer composition demonstrate an improved blend of properties, specifically improved impact resistance, clarity (less haze), and lower levels of entrapped bubbles than traditional water bottles.

BACKGROUND OF THE INVENTION

Branched polycarbonates are known, for example see USP 5,508,359 and 5,804,673. Containers of branched polycarbonate are known; see USP 5,367,044; 6,613,869; and US Publication Number 203/0209553. Containers of branched polycarbonate exhibit numerous advantageous properties, such as for example elevated transparency, good mechanical properties, elevated resistance to environmental influences and a long service life together with low weight and straightforward, low-cost producibility. Polycarbonate containers are produced, for example, using the extrusion blow molding process or the injection blow molding process.

In the extrusion blow molding (EBM) process, the pellets are generally melted with a single screw extruder and are shaped by a die to form a free-standing tube, which is subsequently enclosed by a blowing mold, which pinches together the bottom of the tube. The tube is inflated within the mold, thus being shaped as desired. After a cooling period, the mold is opened and the hollow article may be removed. It is advantageous to use branched polycarbonate which has high melt strength for extrusion blow molding in order to ensure elevated melt stability. The injection stretch blow molding (ISBM) process is a combination of injection molding and blow molding. The process proceeds in three stages: 1) injection molding of the parison in the plastic temperature range of the polycarbonate, 2) inflation of the parison in the thermoplastic range of the polycarbonate (the core of the injection molding tool is simultaneously the blowing mandrel), and 3) stripping of the hollow article and, optionally, cooling of the blowing mandrel with air.

Known containers of conventional polycarbonate exhibit the disadvantage that they do not meet certain requirements for practical use. If known containers of polycarbonate are subjected to severe mechanical stress, the container may burst. This may occur, for example, if a liquid-filled container is dropped from some height onto the ground, for example from the loading area of a truck in which the container is being transported. The use of branched polycarbonates have somewhat alleviated, but not completely eUminated, this impact resistant disadvantage. However, conventional branched polycarbonates create other deficiencies in molded containers, for example it is common to have entrapped bubbles in the bottles and/or reduced clarity, or haze, resulting from flow lines, and/or inconsistent wall thicknesses due to irregular parisons because of inconsistent melt strength.

The object of the invention is accordingly to provide containers of polycarbonate which have greater breaking strength, better clarity (less haze), and reduced bubbles than known containers of polycarbonate.

SUMMARY OF THE INVENTION

The present invention is a method to make an improved branched carbonate polymer composition and blow molded containers therefrom which demonstrate improved impact resistance, lower haze, and reduced bubbles in mold containers.

In one embodiment, the present invention is a process to make a branched carbonate polymer composition comprising the steps of: (i) introducing into an extruder as a dry blend, via one or more separate feeders, as one or more masterbatch, or combinations thereof: (a) a branched carbonate polymer component, (b) a first linear carbonate polymer component having a melt flow rate equal to or less than 3.55 grams per 10 minutes, (c) a second linear carbonate polymer component having a melt flow rate equal to or greater than 10.61 grams per 10 minutes, and (d) one or more additive selected from a pigment, a dye, an antioxidant, a heat stabilizer, an ultraviolet light absorber, a mold release agent, or an optical brightener, wherein the melt flow rates are determined according to ASTM D 1238 at 300°C under a load of 1.2 kg, and the ratio of melt flow rates of (b):(c) is equal to or greater than 1:3, (ii) melt-blending components (a), (b), (c), and (d), and (iii) isolating the melt-blended branched carbonate polymer composition as pellets.

In another embodiment, the present invention is a process to blow mold a hollow container comprising a branched carbonate polymer composition wherein the branched carbonate polymer composition comprises: (a) a branched carbonate polymer component, (b) a first linear carbonate polymer component having a melt flow rate equal to or less than 3.55 grams per 10 minutes, (c) a second linear carbonate polymer component having a melt flow rate equal to or greater than 10.61 grams per 10 minutes, and (d) one or more additive selected from a pigment, a dye, an antioxidant, a heat stabilizer, an ultraviolet light absorber, a mold release agent, or an optical brightener, wherein the melt flow rates are determined according to ASTM D 1238 at 300°C under a load of 1.2 kg, and the ratio of melt flow rates of (b):(c) is equal to or greater than about 1:3.

In another embodiment, the present invention is a process to blow mold a hollow container comprising a branched carbonate polymer comprising the steps of: (i) providing to an extrusion blow molding machine or an injection stretch blow molding machine a melt- blended branched carbonate polymer composition comprising: (a) a branched carbonate polymer component, (b) a first linear carbonate polymer component having a melt flow rate equal to or less than 3.55 grams per 10 minutes, (c) a second linear carbonate polymer component having a melt flow rate equal to or greater than 10.61 grams per 10 minutes, and (d) one or more additive selected from a pigment, a dye, an antioxidant, a heat stabilizer, an ultraviolet light absorber, a mold release agent, or an optical brightener, wherein the melt flow rates are determined according to ASTM D 1238 at 300°C under a load of 1.2 kg, and the ratio of melt flow rates of (b):(c) is equal to or greater than 1:3 and (ii) extrusion blow molding or injection stretch blow molding said melt-blended branched carbonate polymer composition into a hollow container.

In yet another embodiment, the present invention is a process to blow mold a hollow container comprising a branched carbonate polymer comprising the steps of: (i) introducing into an extrusion blow molding machine or an injection stretch blow molding machine the following components as a dry blend, via one or more separate feeders, as one or more masterbatch, or combinations thereof: (a) a branched carbonate polymer component, (b) a first linear carbonate polymer component having a melt flow rate equal to or less than 3.55 grams per 10 minutes, (c) a second linear carbonate polymer component having a melt flow rate equal to or greater than 10.61 grams per 10 minutes, and (d) one or more additive selected from a pigment, a dye, an antioxidant, a heat stabilizer, an ultraviolet light absorber, a mold release agent, or an optical brightener, wherein the melt flow rates are determined according to ASTM D 1238 at 300°C under a load of 1.2 kg, and the ratio of melt flow rates of (b):(c) is equal to or greater than 1:3 and (ii) extrusion blow molding or injection stretch blow molding said melt-blended branched carbonate polymer composition into a hollow container.

A preferred embodiment of the processes described hereinabove, the branched carbonate polymer composition comprises: (a) from 40 to 60 parts of the branched carbonate component having a melt flow rate of from 2.3 to 3.2 g/10 min, (b) from 60 to 40 parts of the first linear carbonate polymer component, and (c) from 2 to 10 parts of the second linear carbonate polymer component.

A preferred embodiment of the processes described herein above, the hollow container is a water bottle.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a cross section through a rotationally symmetrical water bottle.

FIG. 2 compares the shear-thinning characteristics for Example land Comparative

Examples A, B, and F.

FIG. 3 is a copy of two photographs which visually compare the clarity of a water bottle made by the process of the present invention compared to a water bottle which is not made by the process of the present invention.

DETAILED DESCRIPTION

Blends of a branched carbonate with a linear carbonate are known, USP 5,508,359 and 5,804,673; and such blends for use in molded containers are known, USP 5,367,044 and 6,613,869. In conventional blends of branched polycarbonate and linear polycarbonate for use to produce containers by blow molding, the molecular weights of both components were comparable and relatively high (low melt flow rates). The present invention differs from the prior art in that the branched carbonate polymer composition of the present invention for use in molded containers comprises a hither unknown blend of a branched polycarbonate component with at least two linear polycarbonate components, a higher molecular weight linear component and a lower molecular weight linear component, said linear components having a ratio of melt flow rates of about 1:3 or greater.

Not to be held to any particular theory, we believe the presence of the higher melt flow linear carbonate component provides for the improved blend of impact properties, melt strength consistency, clarity (reduced haze by decreasing the visibility of flow lines), and lower bubble entrapment in the molded container by improving the compatibility between the lower melt flow branched component and lower melt flow linear component in the branched carbonate polymer composition. The presence of air bubbles is more than an aesthetic issue (decreasing clarity, unsightly, perceived low quality, etc.). Carbonate polymers demonstrate notch sensitivity to impact resistance, any imperfection, such as a bubble (or other foreign body), can drastically reduce polycarbonate impact resistance by up to a factor of 10 (as tested by notched Izod impact resistance). We believe the improved impact resistance in the carbonate composition of the present invention results from a combination of improved compatibility between the carbonate components and the reduction of entrapped bubbles.

Component (a) of the present invention. is a branched carbonate resin. The branched carbonate polymers, preferably higher molecular weight branched carbonate polymers, suitable for use in the first component in the compositions according to the present invention can be prepared by techniques known in the literature. Unless otherwise indicated, the references to "molecular weight" herein refer to weight average molecular weights ("Mw") determined on the carbonate polymers using gel permeation chromatography with a bisphenol A polycarbonate standard. Otherwise, viscometry or light scattering can also be used to determine weight average molecular weight if similar results are obtained. It should be noted that various references refer to "viscosity average" molecular weight, which is not the same as "weight average" molecular weight but can be correlated or converted to Mw values.

In general, these carbonate polymers are prepared from one or more multihydric components by reacting the multihydric compound, such as a diphenol, with a carbonate precursor such as phosgene, a haloformate or a carbonate ester such as diphenyl or dimethyl carbonate. Aromatic carbonate polymers are preferred and aromatic diphenols are preferred for use as at least part of the multihydric compound with preferred diphenols including but not limited to 2,2-bis (4-hydroxyphenyl)-propane (that is, bisphenol A), phenol, 4,4'-(9-H- fluorene-9-ylidene)bis (that is, bishydroxyphenylfluorene), 4,4'-thiodiphenol (TDP), 1,1 -bis (4-hydroxyphenyl)-l -phenyl ethane (bisphenol AP); phenolphthalein; bis (4- hydroxyphenyl) diphenyl methane; tetrabromobisphenol A (TBBA); and

tetrachlorobisphenol A (TCBA). These carbonate polymers also include aromatic carbonate polymers prepared from two or more different dihydric phenols or a combination of a dihydric phenol and a glycol or a hydroxy- or acid-terminated polyester or a dicarboxylic acid in the event a carbonate copolymer or heteropolymer is desired.

The branched carbonate polymer component can be prepared from such materials by any of several known processes such as the known interfacial, solution or melt processes. Suitable types and amounts of chain terminators (typically monophenolic compounds) and/or branching agents (typically phenols having three or more hydroxy or condensation reactive groups) can be employed to obtain the desired molecular weight and branching degrees in the higher molecular weight branched component. Suitable branching agents are generally one or more of the following: phloroglucin; phloroglucid; 2,6-dimethyl-2,4,6- tri(4-hydroxyphenyl)heptene-3 ; 4,6-dimethyl-2,4,6-tri(4-hydroxyphenyl)heptene-2; 4,6- dimethyl-2,4,6-tri(4-hydroxyphenyl)pentene-2; 4,6-dimethyl-2,4,6-tri(4- hydroxyphenyl)pentane; l,3,5-tri(4-hydroxyphenyl)benzene; l,3,5-tri(2- hydroxyphenyl)benzol; l,l,l-tri(4-hydroxyphenyl)ethane (THPE); 2,6-bis(2-hydroxy-5- methylbenzyl)-4-methylphenol; tetra(4-hydroxyphenyl)methane; trisphenol; bis(2,4- dihydroxyphenyl)ketone; l,4-bis(4,4-dihydroxytriphenylmethyl)benzene; a, a', a"- tri(4- hydroxyphenyl)-l,3,5-tri-isopropylbenzene; 3,3-bis(4-hydroxyaryl)oxyindole;

isatinbisphenol; 5-chloroisatin; 5,7-dichloroisatin; 5-bromoisatin; trimellitic acid;

pyromellitic acid; benzophenonetetra-carboxylic acid; and including for the appropriate compounds, the acid chlorides or other condensation reactive derivatives thereof such as trimellitic trichloride, trimesoylchloride and trimellitic anhydride chloride. Specifically preferred branching agents include phloroglucin; phloroglucid; 1,1,1 -tri(4- hydroxyphenyl)ethane; trimellitic acid; trimellitic trichloride; pyromellitic acid;

benzophenonetetracarboxylic acid and acid chlorides thereof; 2,6-bis(2-hydroxy-5- methylbenzyl)-4-methylphenol and l,3,5-tri(4-hydroxyphenyl)benzene.

As used herein, the term "interfacial carbonate polymer polymerization process" refers to a process where the multihydric reactants, including any multi- or mono-reactive compounds used to incorporate the latently reactive moiety, are dissolved in a water phase by forming an alkali metal adduct, then reacted with the carbonate polymer precursor forming a polymer which is dissolved in a separate organic phase. For example, dihydric phenols are dissolved as alkali metal phenates for reaction with the carbonate precursor forming an aromatic carbonate polymer which is dissolved in a separate organic phase. As those skilled in this area know, nitrogen-containing moieties, such as the unsaturated imido compounds of USP 3,652,715 and 3,770,697, cannot generally be present or incorporated in such a process and are therefore not suitable for use in aspect of the present invention.

In general, by whatever production technique it is prepared, the branched carbonate polymer component (a) should have a weight average molecular weight of equal to or greater than about 34,600, preferably equal to or greater than about 35,800, and more preferably equal to or greater than about 37,000. In order to obtain polymer blends with minimized levels of gels and other beneficial effects of the branched carbonate polymer component (a), it has been found that the weight average molecular weight of the branched carbonate polymer component (a) should not be higher than about 41,000, preferably not higher than 39,800, preferably not higher than about 39,000, more preferably not higher than about 38,200, most preferably not higher than about 37,400.

All melt flow rates herein, unless otherwise indicated, are determined according to ASTM D 1238 at 300°C under a load of 1.2 kg. In this range it has been found that the branched carbonate polymer component (a) should have a melt flow rate (MFR) of equal to or greater than about 0.83 grams per 10 minutes, preferably equal to or greater than about 1.25 grams per 10 minutes (g/10 min), preferably equal to or greater than about 1.54 g/10 min, more preferably equal to or greater than about 1.82 g/10 min and most preferably equal to or greater than about 2.1 g/10 min and preferably equal to or less than about 3.55 g/10 min, preferably equal to or less than about 3.1 g/10 min, more preferably equal to or less than about 2.67 g 10 min, most preferably equal to or less than about 2.25 g/10 min.

In general, the presence and degree of branching can be determined in the branched carbonate polymer component by measuring the concentration of reacted branching agent in the branched carbonate polymer. The concentration of reacted branching agent in the high molecular weight branched carbonate polymer component can typically be determined by IR or NMR spectroscopy or by liquid chromatography, depending upon the nature of the branching agent. It has been found that levels of branching agent in the branched carbonate polymer components for use in the present invention should be in the range of from about 0.005 to about 1 mole branching agent per mole of dihydroxy compound, preferably from about 0.01 to about 0.8, and more preferably from about 0.1 to about 0.6.

In general, it has been found that the branched component is sufficiently branched if it has a higher degree of "shear thinning" than a linear resin of the same molecular weight and will then provide a higher degree of "shear thinning" in the final blend composition at an appropriate level of incorporation.

This improvement in the shear thinning in the blend composition means that if the viscosities of the blend composition and the linear carbonate polymer component alone are independently measured at increasing levels of shear, the measured viscosity of the claimed blend composition is observed to be reduced to a greater degree or at a greater rate than observed for the linear carbonate polymer component without the branched component. It has been found that branched components with higher degrees of branching will provide shear sensitivity improvements at lower levels while lower degrees of branching will conversely require use of the component in larger amounts to provide shear sensitivity improvements. These measurements of shear sensitivity can be done by standard techniques with oscillatory shear rheometry using a Dynamic Mechanical Spectrometer (DMS) or by steady state capillary rheometry using a capillary rheometer.

In particular, a fairly standard measurement technique for shear sensitivity of carbonate polymers involves measuring the apparent viscosity at different apparent shear rates in a capillary rheometer in a shear rate range of 15 to 500 inverse seconds (s-1) and/or measuring the complex viscosity at different frequencies in a frequency range of 0.1 to 100 radians per second (rad.s-1) by DMS (Dynamic Mechanical Spectroscopy) at a temperature of 280°C.

As initially published by W. P. Cox and E. H. Merz in the Journal of Polymer Science Vol. XXVTfl, Issue nr 118 (1958), pp. 619-622, there is a correlation and general equivalence between DMS and capillary rheometry to evaluate the shear sensitivity and melt strength/viscosity properties of a polymer.

To quantify shear sensitivity for practical use over a wide range of shear rates, the complex viscosity at.0.1 ra&s^"1 (equivalent to s-1) from the DMS analysis can be divided by the apparent viscosity at 450 s ¹ from the capillary data. Using this viscosity ratio number, it can be seen that the shear sensitivity properties of the compositions of the present invention are improved compared to those of branched polycarbonates of the same processability (viscosity value at high shear rate) or the same melt strength (viscosity value at low shear rate). An increase of 10 percent in this viscosity ratio number compared to the comparative resin is found to be significant with respect to improving the property balance of the resin, particularly melt strength.

In general, it has been found suitable to employ the branched carbonate polymer component (a) in the branched carbonate polymer composition of the present invention in amounts of equal to or greater than 20 parts by weight, desirably equal to or greater than 30 parts by weight, preferably equal to or greater than 40 parts by weight, and more preferably equal to or greater than 50 parts by weight, said parts by weight being based on the total weight of the branched carbonate polymer composition. In order to maintain processability and thermoplasticity, the branched carbonate polymer component (a) is employed in amounts less than or equal to about 90 parts by weight, preferably less than or equal to about 70 parts by weight, and more preferably less than or equal to about 60 parts by weight, said parts by weight being based on the total weight of the branched carbonate polymer composition.

As mentioned above, the level of branching in the branched component affects the level of branched component necessary to provide the desired degree of shear sensitivity in the claimed carbonate polymer compositions. The amounts of branched component can, therefore, be optimized for particular levels of branching in the branched component.

Components (b) and (c) of the present invention are linear carbonate polymers.

Linear carbonate polymers are known in the literature and commercially available. As known, these linear carbonate polymers are prepared from the dihydric components and by processes as listed above for the branched carbonate polymers without the use of branching agent. As is also well known, suitable chain terminators (typically monophenolic

compounds) can be employed to obtain the desired molecular weights in the higher and lower molecular weight linear carbonate polymer components such that component (b) has a higher molecular weight than component (c).

For purposes of obtaining desired melt strength during extrusion and blow molding and impact resistance and reduced haze in the final molded parts, it has been found that the first, higher molecular weight linear carbonate polymer component (b) should have a weight average molecular weight of equal to or greater than about 38,500, preferably equal to or greater than about 39,000, more preferably equal to or greater than about 40,000, and most preferably equal to or greater than about 41,000. In order to keep the desired level of polymer melt flow and processability it has been found that the first, higher molecular weight linear carbonate polymer component (b) should have a weight average molecular weight of equal to or less than about 43,000, preferably equal to or less than about 42,500, more preferably equal to or less than about 42,000, most preferably equal to or less than about 41,500.

In this range it has been found that the first, higher molecular weight linear carbonate polymer component (b) should have MFR of equal to or greater than about 2.19 grams per 10 minutes, preferably equal to or greater than about 2.31 grams per 10 minutes (g/10 min), preferably equal to or greater than about 2.43 g 10 min, and most preferably equal to or greater than about 2.56 g/10 min and preferably equal to or less than about 3.55 g/10 min, preferably equal to or less than about 3.36 g/10 min, more preferably equal to or less than about 3.01 g/10 min, most preferably equal to or less than about 2.7 g/10 min.

In general, it has been found suitable to employ the first, higher molecular weight linear carbonate polymer component (b) in the branched carbonate polymer composition in amounts of equal to or greater than about 10 parts by weight, desirably equal to or greater than 20 parts by weight, preferably equal to or greater than 30parts by weight, and more preferably equal to or greater than 40 parts by weight, said parts by weight being based on the total weight of the branched carbonate polymer composition. In general, the first, higher molecular weight linear carbonate polymer component (b) is employed in amounts less than or equal to about 90 parts by weight, preferably less than or equal to about 80 parts by weight, preferably less than or equal to about 60 parts by weight, preferably less than or equal to about 50 parts by weight, and more preferably less than or equal to about 45 parts by weight, parts by weight based on the total weight of the branched carbonate polymer composition.

For purposes of obtaining desired melt strength during extrusion and blow molding and impact resistance and reduced haze in the final molded parts, it has been found that the second, lower molecular weight linear carbonate polymer component (c) should have a weight average molecular weight of equal to or greater than about 26,000, preferably equal to or greater than about 26,500, more preferably equal to or greater than about 27,000, and most preferably equal to or greater than about 27,500. In order to keep the desired level of polymer melt flow and processability it has been found that the second, lower molecular weight linear carbonate component (c) should have a weight average molecular weight of equal to or less than about 30,000, preferably equal to or less than about 29,000, more preferably equal to or less than about 28,500, most preferably equal to or less than about 28,000.

In this range it has been found that the second, lower molecular weight linear carbonate polymer component (c) should have MFR of equal to or greater than about 10.61 grams per 10 minutes, preferably equal to or greater than about 11.42 grams per 10 minutes (g/10 min), preferably equal to or greater than about 12.31 g/10 min, more preferably equal to or greater than about 13.28 g/10 min and most preferably equal to or greater than about 14.35 g/10 min and preferably equal to or less than about 19.86 g/10 min, preferably equal to or less than about 18.27 g/10 min, more preferably equal to or less than about 16.83 g/10 min, most preferably equal to or less than about 15.53 g/10 min.

In general, it has been found suitable to employ the second, lower molecular weight linear carbonate polymer component (c) in the branched carbonate polymer composition in amounts of equal to or greater than about 2 parts by weight, desirably equal to or greater than 3 parts by weight, preferably equal to or greater than 4 parts by weight, and more preferably equal to or greater than 5 parts by weight, said parts by weight being based on the total weight of the branched carbonate polymer composition. In general, the second, lower molecular weight linear carbonate polymer component (c) is employed in amounts less than or equal to about 10 parts by weight, preferably less than or equal to about 9 parts by weight, preferably less than or equal to about 8 parts by weight, preferably less than or equal to about 7 parts by weight, and more preferably less than or equal to about 6 parts by weight, parts by weight based on the total weight of the branched carbonate polymer composition.

The linear components in the blends of the present invention are produced separately from and do not include the unbranched (i.e., linear) polymer produced at the same time and contained in the branched carbonate polymer component (a). The two linear carbonate polymer components (b) and (c) and the branched carbonate polymer component (a) need to be produced separately (i.e., independently of each other, in separate reactors and/or different times in the same reactor(s)) in order to obtain the desired molecular weight and structure characteristics of each component that produce the desired properties in the claimed blend.

Preferably component (b) and component (c) have a MFR ratio of equal to or greater than 1:2, more preferably equal to or greater than 1:2.5, more preferably equal to or greater than 1:3, more preferably equal to or greater than 1:3.5, more preferably equal to or greater than 1:4, more preferably equal to or greater than 1:4.5, more preferably equal to or greater than 1:5, more preferably equal to or greater than 1:5.5, and more preferably equal to or greater than 1:6. As herein defined, ratios are rounded to the nearest whole number, for example, 1:2.98 would be round to 1:3.

The suitable branched and linear carbonate polymer components in the present invention also include carbonate polymers prepared from two or more different

multihydroxy compounds, preferably dihydroxy compounds, and preferably phenols, or a combination of a multihydroxy compound, such as a diphenol, and a glycol or a hydroxy- or acid-terminated polyester or a dicarboxylic acid in the event a carbonate copolymer or heteropolymer is desired. It is also possible to employ multifunctional carboxylic acids, especially aromatic carboxylic acids, and prepare poly(ester-carbonate) resins such as the known aromatic poly(estercarbonates). The known silicon-containing carbonate monomers can also be used to prepare silicon-containing carbonate polymers that are suitable for use in the blends according to the present invention.

One of the key features of the branched carbonate polymer resin blend compositions according to the present invention and suitable for use in the processes and articles according to the present invention is that the blend compositions have a weight average molecular weight within the desired range. For purposes of obtaining desired melt strength during extrusion and blow molding and impact resistance and reduced haze in the final molded containers, it has been found that the blends should have a weight average molecular weight of equal to or greater than about 35,600, more preferably equal to or greater than about 36,400 and most preferably equal to or greater than about 37,200. In order to keep the desired level of polymer melt flow and processability it has been found that the blends should have a weight average molecular weight of equal to or less than about 39,000, preferably equal to or less than about 38,600, more preferably equal to or less than about 38,200 most preferably equal to or less than about 37,800. In this range it has been found that the resin blend compositions should have a melt flow rate of equal to or greater than about 2.05 g 10 min, preferably equal to or greater than about 2.22 g/10 min, and more preferably equal to or greater than about 2.39 g/10 min and preferably equal to or less than about 3.47 g/10 min, preferably equal to or less than about 3.14 g/10 min, and more preferably equal to or less than about 2.89 g/10 min.

As component (d), individually, one or more of the linear carbonate polymer components and/or the branched carbonate polymer component according to the present invention can advantageously contain the standard types and amounts of the additive-type components frequently incorporated into carbonate polymers for bottle or container applications. In other words individually or collectively one of the components (a), (b), or (c), or two of the components, or all three of the components may comprise one or more additive (d). Component (d) can include one or more pigment, dye, antioxidant, heat stabilizer, ultraviolet light absorber, mold release agent, an optical brightener, and the other additives commonly employed in carbonate polymer compositions.

Preparation of the branched carbonate polymer compositions of this invention can be accomplished by any suitable mixing means known in the art, including dry blending the individual components (a), (b), (c) and (d) and subsequently melt-blending, sometimes referred to as melt-mixing or melt-compounding, either (1) directly in the extruder of an extrusion blow molding machine or an injection stretch blow molding machine used to make the blow molded container (one step process) or (2) melt-blending in a separate melt- mixer (e.g., a single screw extruder, a twin screw extruder, an internal kneader, a Banbury mixer, roll mill, or the like) and isolated as a melt-compounded branched carbonate polymer composition prior to blow molding (two-step process).

In another embodiment, the components (a), (b), (c), and/or (d) can be added directly to the melt-blending apparatus individually via separate feeders and/or one or more components may be dry blended and the remaining feed via one or more individual feeder and/or some of the components may be first made into a masterbatch then melt-blended with the remaining components and/or a combination thereof. If the composition is melt- blended in a separate step from blow molding (i.e., the two step process), the branched carbonate polymer composition is first melt-blended, then comminuted (typically to pellets), isolated, and then secondly used in a blow molding machine to make the container.

Melt-compounding and/or blow molding is preferably achieved at temperatures of from about 200°C to about 300°C.

It has been found that the process for preparing EBM and/or ISBM containers according to the present invention are surprisingly improved by use of the described branched carbonate polymer compositions. As is known, blow molding processes for preparing bottles and containers involve the steps of extrusion of an expandable parison, expansion or blowing of the parison to the desired shape and cooling.

The branched carbonate polymer composition according to the invention is preferably dried before blow molding to ensure that the optical quality of the containers is not impaired by streaks or bubbles and the polycarbonate is not hydrolyzed during processing. The residual moisture content after drying is preferably less than 0.01 weight percent. A drying temperature of 120°C is preferred. Lower temperatures do not ensure adequate drying, while at higher temperatures there is a risk of the individual polycarbonate pellets sticking together, thus rendering them unprocessable. Dry air dryers are preferred. The preferred melt temperature during processing of the polycarbonate according to the invention is 230°C to 300°C.

In a preferred embodiment of the process for the production of the containers according to the invention, the polycarbonates according to the invention are processed in extruders having a smooth or grooved feed zone, preferably a smooth feed zone.

The drive power of the extruder is selected in accordance with the screw diameter. By way of example, at a screw diameter of about 60mm, the drive power of the extruder is in the range of 30 to 40 kW, while at a screw diameter of about 90mm it is in the range of 60 to 70 kW. Multipurpose, three section screws as are conventional for processing industrial thermoplastics are suitable. A screw diameter of from about 50mm to about

60mm is preferred for the production of containers of a volume of 1 liter. A screw diameter of about 70mm to about 100mm is preferred for the production of containers of a volume of 19 liters. The length of the screws is preferably 20 to 25 times the diameter of the screw.

In the blow molding process, the blowing mold is preferably adjusted to a

temperature of 50°C to 90°C in order to obtain a glossy, high quality surface on the container. In order to ensure uniform and effective temperature control of the blowing mold, the temperatures of the base area and the jacket area are separately controllable. The blowing mold is preferably closed with a pinch force of 1000 Newton (N) to 1500 N per centimeter of pinch seam length.

Containers for the purpose of the present invention may be used for the packaging, storage, or transport of liquids, solids, or gases FIG. 1. Containers for the packaging, storage, or transport of liquids (liquid containers) are preferred, with containers for packaging, storage, or transport of water (water bottles) 1 being particularly preferred.

Containers for the purpose of the present invention are hollow articles FIG. 1 having a volume of preferably 0.1 liter (L) to 50 L, more preferably from 0.5 L to 50 L, more preferably with volumes of 1 L, 5 L, 12 L, and 19 L. Water bottles having a volume of 3 to 5 gallons are particularly preferred. The containers of the present invention have an empty weight of preferably 0.1 g to 3000 g, more preferably of 50 g to 2000 g and particularly preferably of 650 g to 900 g.

The wall thicknesses 2 of the containers of the present invention may be a constant uniform thickness, variable thickness, or combination thereof and are preferably from about 0.5mm to about 5mm, more preferably from about 0.8mm to about 4mm thick.

Containers for the purposes of the present invention have a length 3 of preferably about 5mm to about 2000mm, particularly preferably from about 100mm to about 1000mm.

The containers have a maximum circumference 4 of preferably about 10mm to about 250mm, more preferably from about 50mm to about 150mm and very particularly preferably from about 70mm to about 90mm.

Containers for the purposes of the invention preferably have a bottle neck of a length 5 of preferably about 1mm to about 500mm, more preferably of about 10mm to about 250mm, particularly preferably of about 50mm to about 100mm and very particularly preferably of about 70mm to about 80mm.

The wall thickness of the bottle neck 6 of the container preferably ranges between about 0.5mm and about 10mm, particularly preferably from about 1mm to about 10mm and very particularly preferably from about 5mm to about 7mm.

The diameter of the bottle neck 7 ranges between preferably about 5mm to about 200mm; about 10mm to about 100mm are particularly preferred from about 45mm to about 75mm are very particularly preferred.

The bottom of the container 8 according to the invention has a diameter of preferably about 10mm to about 275mm, more preferably of about 50mm to about 150mm and very particularly preferably of about 70mm to about 90mm.

Containers for the purposes of the present invention may have any desired geometric shape, they may for example be round, oval or polygonal or multi-sided having for example 3 to 12 sides. Round, oval and hexagonal shapes are preferred.

The design of the containers may be based on any desired surface textures. The surface textures are preferably smooth, rough 9, or ridged. The containers according to the invention may also exhibit two or more different surface textures. Ribs or beads 10 may run around the circumference of the containers. They may be spaced at will or have any two or more differing spacings. The surface textures of the containers according to the invention may comprise roughened or integrated textures, symbols, ornaments, coats of arms, brands, trademarks, monograms, manufacturer's details, material designations or volume details. The containers according to the invention may have any desired number of handles (not shown in the drawing), which may be located on the sides, top or bottom of the container. The handles may be external or incorporated into the outline of the container. The handles may be collapsible or fixed. The handles may have any desired outline, for example oval, round or polygonal. The handles preferably have a length of about 0.1mm to about 180mm, preferably of from about 20mm to about 120 mm.

Apart from the branched carbonate polymer composition according to the invention, the containers according to the invention may additionally contain small quantities of other substances, for example seals of rubber or handles of other materials.

The following Experiments are given to further illustrate the invention and should not be construed as limiting its scope. In the following Experiments, all percentages are by weight unless otherwise indicated.

EXAMPLES

To illustrate the practice of this invention, examples of preferred embodiments are set forth below. However, these examples do not in any manner restrict the scope of this invention. Polycarbonate resins A, B, and C available and used in flake form. Each composition has 0.33 parts by weight of a combination of five dyes to provide a blue tint and 0.35 by weight pentaerythritol tetrastearate (PETS) mold release. Example 1 and

Comparative Examples D to F are melt-blended on a JSW TEX single screw extruder. Each polycarbonate resin, the dye, and the mold release are fed via a separate K-Tron weight feeder. The compositions are melt-blended, extruded, and comminuted to pellets. The extruder barrel temperatures for the Comparative Examples and Example are listed in Table 1.

The melt-blended compositions, in the form of pellets, are pre dried at 120°C for 4 hours prior to extrusion blow molding. Dried pellets for Example 1 and Comparative Examples D, E, and F are extrusion blow molded into 19 L water bottles using a HC 82PC Machine manufactured by Zhangjiagang Huafeng Heavy-Duty Equipment Manufacturing Co., Ltd. The composition is fed from the hopper into the extruder barrel temperature of 275 °C where it is melted and the molten resin fills an accumulator chamber. The accumulator chamber is heated and the temperatures for the Comparative Examples and Example are listed in Table 1. When the accumulation chamber is full, hydraulic pressure is activated to the plunger, forcing the resin through the annular die having a nominal die gap of 1.5mm and forming a parison at a length about 600mm. The bottle mold is closed around the parison sealing the ends except for an area in which air can enter. The hollow parison is then inflated with air at a pressure about 5 to 10 bars to take up the shape of the chilled mold. Air pressure is maintained until the plastic has cooled sufficiently to eject the part from the mold. The molds open to release the bottle which is then ready for external trimming of "flash", or scrap plastic. The 19 L water bottles measure 490mm in height and 270mm in circumference and weigh about 750 g.

In Table 1 and for the following polymer components: MFR is determined according to ASTM D 1238 at 300°C under a load of 1.2 kg, molecular weight is determined by gel permeation chromatography (GPC) with bisphenol-A polycarbonate standard, Mw is weight average molecular weight, Mn is number average molecular weight, Mw/Mn is the polydispersity, viscosity is measured by capillary rheometry at 270°C and 205 reciprocal seconds (s ¹) and is reported in Pascal seconds (Pa s), and haze and transmittance are reported in percent.

"br PC" is a branched bisphenol-A polycarbonate branched with about 0.5 percent THPE having a MFR of 2.77 g/10 min, a Mw of 37,047, Mn of 12,111 , Mw/Mn of 3.06, viscosity of 1,897 Pa s, haze of 0.63 percent and transmittance of 80.4 %;

"In PC-1" is a linear bisphenol-A polycarbonate having a MFR of 3.01 g/10 min, a Mw of 40, 145, a Mn of 14,503, a Mw/Mn of 2.77, a viscosity of 3,262 Pa s, a haze of 0.72 percent, and a transmittance of 80.2 percent; and

"In PC- 2" is a linear bisphenol-A polycarbonate having a MFR of 14 g 10 min, a Mw of 28,100, a Mn of 10,600, a Mw/Mn of 2.65, a viscosity of 620 Pa s, a haze of 0.71 percent, and a transmittance of 80.3 percent.

In Table 1, the following qualitative analysis for water bottles made from the branched carbonate compositions Comparative Examples D, E, and F and Example 1:

"Izod" is notched Izod impact testing performed according to ASTM D 256;

"2' Drop Test" is an end product use test where the bottle is filled with water, capped, and dropped from 10 meters, two times. If the bottle maintains its integrity (i.e., does not break, leak, or crack) it passes, if it does not maintain its integrity and it breaks, cracks, or otherwise looses water, it fails; "Melt Strength" is a reflection of the constancy in forming the parison, a poor rating indicated inconstancy/fluctuations (length and/or thickness) in the parison as it forms and a good rating indicates consistency in parison formation;

"Bubble Formation" is a visual comparison of the amount/numbers of bubbles formed in the bottle;

"Clarity" which is reflected by transmittance and haze values is a visual comparison of acceptability, see FIG. 3; and

"Reject Rate" is a gauge of the number of bottles meeting quality control standards, acceptable bottles versus unacceptable bottles. The variables (1) fluctuations in the parison, (2) bubble content, and/or (3) clarity are used to determine acceptability. A high rejection rate reflects an unacceptable number of defective bottles whereas a low rejection rate reflects an acceptable number of bottles passing quality control.

FIG. 2 is a graphical representation of the viscosities for Comparative Example A, B, and F and Example 1. Between shear rates of 130~207 s^"1, the compositions have viscosities of 3300 to 4150, 2060 to 2650, 1980 to 2510, and 1520 to 1850 Pa.s, for

Examples B, F, 1 and A, respectively. Melt strength comparisons are made at a shear rate of 18 s^"1 and the compositions have the following values 7085, 6246, 6112 and 5166 Pa.s, for Examples B, F, 1 and A, respectively.

FIG. 3 is a copy of a photograph visually comparing and demonstrating the significantly improved clarity of a water bottle made by the process of the present invention comprising a branched carbonate polymer composition having a higher melt flow rate linear carbonate component (Example 1) versus a water bottle not made by the process of the present invention comprising a branched carbonate composition lacking a higher melt flow rate linear carbonate component (Comparative Example F). Example 1 has a light transmittance of about 80.3 percent and lower haze of about 0.64 percent while Example F only achieves a light transmittance of 79.9 percent and higher haze of 0.71 percent. Table 1

Claims

CLAIMS:

1. A process to make a branched carbonate polymer composition comprising the steps of:

(i) introducing into an extruder as a dry blend, via one or more separate feeders, as one or more masterbatch, or combinations thereof:

(a) a branched carbonate polymer component,

(b) a first linear carbonate polymer component having a melt flow rate equal to or less than 3.55 grams per 10 minutes,

(c) a second linear carbonate polymer component having a melt flow rate equal to or greater than 10.61 grams per 10 minutes,

and

(d) one or more additive selected from a pigment, a dye, an antioxidant, a heat stabilizer, an ultraviolet light absorber, a mold release agent, or an optical brightener,

. wherein the melt flow rates are determined according to ASTM D 1238 at 300°C under a load of 1.2 kg, and the ratio of melt flow rates of (b):(c) is equal to or greater than 1:3,

(ii) melt-blending components (a), (b), (c), and (d),

and

(iii) isolating the melt-blended branched carbonate polymer composition as pellets.

2. A process to blow mold a hollow container comprising a branched carbonate polymer composition wherein the branched carbonate polymer composition comprises:

(a) a branched carbonate polymer component,

and

(d) one or more additive selected from a pigment, a dye, an antioxidant, a heat stabilizer, an ultraviolet light absorber, a mold release agent, or an optical brightener, wherein the melt flow rates are determined according to ASTM D 1238 at 300°C under a load of 1.2 kg, and the ratio of melt flow rates of (b):(c) is equal to or greater than 1:3.

3. A process to blow mold a hollow container comprising a branched carbonate polymer comprising the steps of:

(i) providing to an extrusion blow molding machine or an injection stretch blow molding machine a melt-blended branched carbonate polymer composition comprising:

(a) a branched carbonate polymer component,

and

wherein the melt flow rates are determined according to ASTM D 1238 at 300°C under a load of 1.2 kg, and the ratio of melt flow rates of (b):(c) is equal to or greater than 1:3

and

(ii) extrusion blow molding or injection stretch blow molding said melt-blended branched carbonate polymer composition into a hollow container.

4. A process to blow mold a hollow container comprising a branched carbonate polymer comprising the steps of:

(i) introducing into an extrusion blow molding machine or an injection stretch blow molding machine the following components as a dry blend, via one or more separate feeders, as one or more masterbatch, or combinations thereof:

(a) a branched carbonate polymer component,

and (d) one or more additive selected from a pigment, a dye, an antioxidant, a heat stabilizer, an ultraviolet light absorber, a mold release agent, or an optical brightener,

and

5. The process of Claims 1 , 2, 3, or 4 wherein the branched carbonate polymer composition comprises:

(a) from 40 to 60 parts of the branched carbonate component having a melt flow rate of from 2.3 to 3.3 g/10 min,

(b) from 60 to 40 parts of the first linear carbonate polymer component, and

(c) from 2 to 10 parts of the second linear carbonate polymer component.

6. The process of Claims 2, 3, or 4 wherein the hollow container is a water bottle.