CA2163660A1 - Polyester/zeolite admixtures - Google Patents
Polyester/zeolite admixturesInfo
- Publication number
- CA2163660A1 CA2163660A1 CA002163660A CA2163660A CA2163660A1 CA 2163660 A1 CA2163660 A1 CA 2163660A1 CA 002163660 A CA002163660 A CA 002163660A CA 2163660 A CA2163660 A CA 2163660A CA 2163660 A1 CA2163660 A1 CA 2163660A1
- Authority
- CA
- Canada
- Prior art keywords
- polyester
- zeolite
- zsm
- ppm
- pore
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K3/00—Use of inorganic substances as compounding ingredients
- C08K3/34—Silicon-containing compounds
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K7/00—Use of ingredients characterised by shape
- C08K7/22—Expanded, porous or hollow particles
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K2201/00—Specific properties of additives
- C08K2201/008—Additives improving gas barrier properties
Landscapes
- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Compositions Of Macromolecular Compounds (AREA)
- Polyesters Or Polycarbonates (AREA)
Abstract
This invention relates to a polyester/zeolite admixture having an excellent gas barrier property and an improved flavor retaining property, and clarity. More particularly, the present invention relates to a polyester/zeolite admixture wherein the zeolite is present in a critical amount of 100 parts per million (ppm) to 1,000 ppm. The present inventors have determined that addition of small- or medium-pore zeolites in a critical amount to a polyester reduces the concentration of acetaldehyde in the polyester without producing haze and thus improves the storage property, flavor retaining property, and fragrance retaining property of containers made from such polyester.
Description
g ~ O
POLYESTER/ZEOLITE ADM~ KES
FIELD OF THE INVENTION
This invention relates to a heat-molded or draw-formed plastic article having improved flavor retainingproperties and clarity. More particularly, the present invention relates to a plastic article prepared from a polyester~small-pore or medium pore zeolite admixture wherein the zeolite is present in a critical amount of 500 to 1000 parts per million based on the weight of the polyester.
BACKGROUND OF THE INVENTION
Polyesters such as polyethylene terephthalate (PET) are widely used for the production of light weight plastic articles since PET is excellent in mechanical properties such as formability and creep resistance and can be biaxially molecularly oriented. However, during molding or extrusion processes, acetaldehyde is formed by thermal decomposition of the polyester and when the polyester is formed into an article, the acetaldehyde in the article walls migrates into the contents of the article. Small amounts of acetaldehyde adversely affect the flavor retaining property of foods and beverages, and the fragrance retaining property of foods, beverages, cosmetics, and other package contents. For these reasons, it is desirable to minimize the migration of acetaldehyde into package contents.
The use of zeolites in polyesters is disclosed in U.S. Pat. Nos. 3,876,608, 4,391,971 and 5,104,965, and PCT International Publication No. WO 90/03408.
U.S. Pat. No. 3,876,608 discloses the addition of 13X or 4A zeolite in polyesters as a inert filler to increase surface roughness of polyester films. In this disclosure, the molten polymer film is contacted with a AMENDED S~lEET
IPEA/EP
- ~163~60 cooling quench drum to obtain amorphous polymer prior to biaxial orientation. Acetaldehyde is not mentioned.
U.S. Pat. No. 4,391,971 discloses a method for reducing the acetaldehyde content in PET by passing the PET through a bed of zeolite pellets. In this disclosure, the zeolite is not admixed with the polyester.
U.S. Pat. No. 5,104,965 discloses a process for preparing a crystalline polyethylene terephthalate which contains greater than 1000 ppm of a zeolite. No mention is made of acetaldehyde or haze. In contrast, the present inventors have determined that a polyester~zeolite admixture wherein the zeolite is present in a critical amount of 500 parts per million (ppm) to 1000 ppm imparts adequate reduction in residual acetaldehyde without imparting haze to the polyester and thus improves the storage property, flavor retaining property, and fragrance retaining property of containers made from such polyesters. If smaller amounts of zeolite is used, an acceptable level of haze can be achieved, however, residual acetaldehyde is very large.
On the other hand, if larger amounts of zeolite is used, residual acetaldehyde can be reduced but only at the expense of haze.
PCT International Publication No. WO 90~03408 discloses a process for making oriented PET film containing zeolites as slip additives. The use of zeolites as polymerization catalysts in PET is also disclosed. No mention is made of bottle or sheet applications, only oriented film primarily for magnetic tape applications. Acetaldehyde was not mentioned.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to reduce acetaldehyde contained in a polyester and AMENDED SHEET
IPEA/EP
3~6~
improve the flavor retaining property and fragrance retaining property of contents in a vessel formed from the polyester without imparting haze to the polyester.
Another object of the invention is to provide polyester/zeolite admixtures which exhibit excellent mechanical properties such as impact resistance, stress crack resistance and heat resistance, and which display excellent melt flowability at the time of molding thereof, and to provide processes for preparing said polyester~zeolite admixture.
These and other objects are accomplished herçin by a heat-molded or draw-formed plastic article having improved flavor retaining properties and clarity which comprises a thermoplastic polyester~zeolite composition comprising:
(1) a polyester which comprises (a) a dicarboxylic acid selected from the group consisting of aromatic dicarboxylic acids, saturated aliphatic dicarboxylic acids, cycloaliphatic dicarboxylic acids, and combinations thereof, and (b) a diol component comprising repeat units from at least 50 mole percent ethylene glycol, based on 100 mole percent dicarboxylic acid and 100 mole p-ercent diol; and (2) 500 to 1000 parts per million based on the weight of the polyester of a small-pore or medium pore zeolite.
AM~ E :) SHEET
IPEA/~P
- 21~6q DESCRIPTION OF THE-INVENTION
The polyester, component (1), of the present invention includes copolyesters. The polyester may be crystalline, semi-crystalline or amorphous. The polyester contains repeat units from a dicarboxylic acid and a diol, based on 100 mole percent dicarboxylic acid and 100 mole percent diol. Dicarboxylic acids useful in the present invention include aromatic dicarboxylic acids preferably having 8 to 14 carbon atoms, saturated aliphatic dicarboxylic acids preferably having 4 to 12 carbon atoms, and cycloaliphatic dicarboxylic acids preferably having 8 to 12 carbon atoms. Specific examples of dicarboxylic acids are: terephthalic acid, phthalic acid, isophthalic acid, naphthalene-2,6-dicarboxylic acid, cyclohexanedicarboxylic acid, cyclohexanediacetic acid, diphenyl-4,4'-dicarboxylic acid, succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, and the like. The polyester may be prepared from two or more of the above dicarboxylic acids.
It should be understood that use of the corresponding acid anhydrides, esters, and acid chlorides of these acids is included in the term "dicarboxylic acid".
The diol component contains repeat units from at least 50 mole percent ethylene glycol. Examples of diol comonomers which can be included with ethylene glycol are cycloaliphatic diols preferably having 6 to 15 carbon atoms or aliphatic diols preferably having 3 to 8 carbon atoms. Specific diol comonomers are: 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-methylpentanediol-(1,4), 2,2,4-trimethylpentane-diol-(1,3), 2-ethylhexanediol-(1,3), 2,2-diethylpropane-ND~l~ S~ T
~p.-~'~Ft - - 21 B3~
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. The polyester may be prepared from one or more of the above diols.
- The polyester may also contain small amounts of trifunctional or tetrafunctional comonomers such as trimellitic anhydride, trimethylolpropane, pyromellitic dianhydride, pentaerythritol, and other polyester forming polyacids or polyols generally known in th,e art.
For the purposes of the present invention, the preferred polyester composition contains a dicarboxylic acid component which consists essentially of repeat units from terephthalic acid and a diol component which consists essentially of repeat units from ethylene glycol.
Polyesters useful as component (1) have an inherent viscosity of 0.4 to 1.5 dL~g. Preferably, the polyester has an inherent viscosity of 0.6 to 1.2 dL~g as measured at 25C. using 0.50 grams of polymer per 100 ml of a solvent consisting of 60% by weight phenol and 40% by weight tetrachloroethane. The polyester may be prepared by conventional polycondensation procedures well-known in the art. Such processes include direct condensation of the dicarboxylic acid(s) with the diol(s) or by ester interchange using a dialkyl dicarboxylate. For example, a dialkyl terephthalate such as dimethyl terephthalate is ester interchanged with the diol(s) at elevated temperatures in the presence of a catalyst.
The second component of the present invention is a zeolite. Zeolites are crystalline alumino-silicates with highly ordered crystalline structure. Cavities of a defined size are formed in the rigid, three-dimensional network composed of sio4 - and AMENDED SHEET
IPEAIEP
Z163~60 A104-tetrahedra. The lattice contains cavities of varying diameters, depending on the type of zeolite. A
distinction is made between large-, medium-, and small-pore zeolites. In the case of large-pore Y-zeolites, for example, a cavity of this type having a diameter of 7.4 angstroms is formed by twelve sio4 tetrahedra. In the case of small-pore A-zeolites, eight tetrahedra form a ring of diameter 4.1 angstroms. The medium-pore pentasil zeolites have a 10-ring system with an ellipsoidal tubular diameter of 5.5 angstroms x 5.6 angstroms. All medium-pore zeolites are penta,sil zeolites which contain uniform channels. Small-pore and medium-pore zeolites are suitable for use in this invention. Examples of small-pore zeolites include A-zeolites such as 3A, 4A, and 5A, mordenite (small-pore type) such as zeolites sold under the trademarks AW-300 and ZEOLON-300 which are available from Union Carbide and Norton Company, erionite, chabazite, zeolite F such as IONSIV F80, and zeolite W such as IONSIV W85.
IONSIV is a registered trademark of Union Carbide.
Examples of medium-pore zeolites include ZSM-5, ZSM-11, ZSM-22, NU-10, Theta 1, ZSM-23, ZSM-48, TS-l, and silicalite.
The present inventors have determined that addition of small- or medium-pore zeolites in the range of 500 to 1000 parts per million (ppm) based on the weight of the polyester to the polyester, component 1, reduces the concentration of acetaldehyde in the polyester without producing haze and thus improves the storage property, flavor retaining property, and fragrance retaining property of containers made from such polyester.
The polyester compositions of this invention are prepared by mixing a polyester with small- or medium-pore zeolites. The zeolites can be readily incorporated into the polyester during the AMENDE~ SHEET
IPEA~EP
-- ~163~60 polymerization of the polyester or in a later step by any suitable melt blending process such as batch mixing, single screw, or twin screw extrusion. Preferably, the zeolite is added during polymerization since this method produces less haze then melt blending. Because zeolites can absorb and release large amounts of water and hence contribute to polymer hydrolysis on melt blending, it is preferable to dehydrate the zeolites by heating to a temperature of greater than 350C. before adding the zeolites to the polyester melt.
This invention is useful for various packagi,ng applications. Examples include, but are not limited to, thermoformed or injection molded trays, thermoformed or injection molded cups, extrusion blow molded bottles, injection stretch blow molded bottles, extruded film, and extruded sheet.
The materials and testing procedures used for the results shown herein are as follows:
Acetaldehyde ge~eration (AA Gen) was determined by the following method. After crystallizing for 30 minutes at 180C., the pelletized polyester~zeolite admixture was dried overnight at 120C. in a vacuum oven. A Tinius-Olsen melt indexer was loaded with 5 grams of the polyester or copolyester and held at the test temperature (preferably 275-310C.) for five minutes. The molten polyester was extruded into water and stored at a temperature of -25C. until grinding.
The sample was ground to 20 mesh or finer and 0.5 grams was placed in a sample tube which was immediately sealed. The sample was analyzed by dynamic headspace gas chromatographic analysis using a Hewlett-Packard 5890 Gas Chromatograph with a Perkin Elmer Automatic Thermal Desorption ATD-50 as the injection system.
Acetaldehyde was desorbed by heating the sample at AMENDED S~IEET
IPEA/~P
-~163~6~
150C. for ten minutes. The gas chromatography column had a 30 m by 0.53 mm inside diameter.
Haze was determined by ASTM D1003. Haze values of less than 10% are acceptable for high quality packaging.
The invention will be further illustrated by a consideration of the following examples, which are intended to be exemplary of the invention. All parts and percentages in the examples are on a weight basis unless otherwise stated.
Poly(ethylene terephthalate) was prepared by the following procedure.
Dimethyl terephthalate, 145.5 grams, and 93.0 grams of ethylene glycol were placed in a polymerization reactor along with titanium tetraisopropoxide (20 ppm Ti), manganese acetate (55 ppm Mn), antimony oxide (225 ppm Sb), and cobalt acetate (75-ppm Co). The amount and type of zeolite indicated in Table I was also added.
The mixture was heated with stirring under nitrogen atmosphere at 200 C. for 60 minutes, followed by 220 C. for 60 minutes at which time ZONYL A,-(120 ppm phosphorus) which is available from DuPont, was added.
The reaction temperature was increased to 285 C. and pressure was reduced to 0.3 mm Hg (0.3 torr). When the polymer viscosity reached the desired level, the polymerization was terminated by removing the heat source and venting the reactor to ambient pressure. The resulting polyesters had inherent viscosities of O.50-0.68 dL/g. These polyesters were solid-state polymerized to an inherent viscosity of 0.70-0.72 dL/g.
.9MENDFD S~EI~T
IP~
-TABLE I
ZEOLITE AA GEN HAZE
EXAMPLE (type) (ppm) 275C. 295C. (%) 1 NONE 5.413.4 4.43 2 4A 100 4.311.3 7.25 3 3A 500 4.612.1 6.20 4 13X 500 6.216.6 8.11 3A 500 4.413.0 8.43 6 ALUMINA500 5.412.9 5.72 7 3A 500 4.314.5 6.74 8 SILICA500 6.211.7 6.41 9 ALUMINA500 6.112.8 8.15 4A 5000 2.39.6 44.20 11 4A 500 3.611.2 4.34 12 4A 1000 3.48.4 7.48 13 NONE - 7.419.1 3.20 14 4A 2000 3.716.1 17.97 The results in Table I clearly indicate that addition of small- or medium-pore zeolites, as opposed to using large-pore zeolites such as 13X or similar inorganic materials such as alumina and silica, in the range of 100 to 1000 ppm to a polyester reduces the concentration of acetaldehyde in the polyester without producing an unacceptable level of haze. An unacceptable level of haze has been defined as being greater than 10%.
Poly(ethylene terephthalate) was prepared by the following procedure.
Bis(2-hydroxyethyl) terephthalate, 190.5 grams, was placed in a polymerization reactor along with antimony oxide (225 ppm Sb), cobalt acetate (65 ppm Co) and ZONYL A (80 ppm phosphorus). The amount and type of zeolite indicated in Table II was also added. The mixture was heated with stirring under nitrogen atmosphere to 285 C. and pressure was reduced to 0.3 torr. When the polymer viscosity reached the ,s ~I,~T
3~ ~
desired level, the polymerization was terminated by removing the heat source and venting the reactor to ambient pressure. The resulting polyesters had inherent viscosities of 0.57-0.62 dL~g. These polyesters were solid-state polymerized to an inherent viscosity of 0.70-0.72 dL/g.
TABLE II
ZEOLITE AA GEN HAZE
EXAMPLE (type)(ppm) 275C. 295C. (%) NONE - 2.7 10.52.34 16 NONE 3.7 12.93.28 17 4A 100 3.4 14.03.12 18 4A 250 2.3 14.13.04 19 4A 250 2.5 13.73.49 4A 500 2.5 13.38.03 21 4A 1000 2.5 13.610.47 22 4A 1000 2.3 15.76.51 23 4A 2000 2.1 11.413.54 24 4A 5000 1.7 10.940.18 NONE 3.2 13.02.74 The results in Table II clearly indicate that addition of small- or medium-pore zeolites in the range of 100 to 1000 ppm to a polyester reduce the concentration of acetaldehyde in the polyester without producing an unacceptable level of haze, as compared to polyester compositions without zeolites. The addition of small- and medium-pore zeolites to the polyester prepared using the catalyst system in Examples 1-14 have a greater effect in reducing the acetaldehyde than adding the same types of zeolites to the polyester used in Examples 15-25 which contain less catalyst metals.
AMENDED SHEET
IP!~ P
2163~
A polyester resin was prepared by mixing powdered 4A zeolite, 0.6 grams, with 599.4 grams of KODAPAK
PET 9921W which is available from Eastman Chemical Company, and extruding~pelletizing in a Brabender extruder at 275C. melt temperature. The zeolite was heated at 500C. for 12 hours and the PET was dried at 150C. for 12 hours. The pelletized polyester~zeolite resin was crystallized by heating at 180C. for 30 minutes and dried in a vacuum oven for 12 hours at 120C.
Acetaldehyde generation was 8.1 ppm at 275C. and 18.1 ppm at 29SC. compared to 11.0 ppm at 275C. and 25.5 ppm at 295C. without the zeolite additive.
A polyester resin was prepared by mixing powdered 4A zeolite, 6.0 grams, with 594.0 grams of KODAPAK PET
9921W and extruding/pelletizing in a Brabender extruder at 275C. melt temperature. The zeolite was heated at 500C. for 12 hours and the PET was dried at 150C. for 12 hours. The pelletized polyester/zeolite resin was crystallized by heating at 180C. for 30 min-and dried in a vacuum oven for 12 hours at 120C.
Acetaldehyde generation was 6.7 ppm at 275C. and 12.7 ppm at 295C. compared to 11.0 ppm at 275C. and 25.5 ppm at 295C. without the zeolite additive.
Many variations will suggest themselves to those skilled in this art in light of the above detailed description. All such obvious modifications are within the full intended scope of the appended claims.
AMENDED S~IEET
IPEA/FP
POLYESTER/ZEOLITE ADM~ KES
FIELD OF THE INVENTION
This invention relates to a heat-molded or draw-formed plastic article having improved flavor retainingproperties and clarity. More particularly, the present invention relates to a plastic article prepared from a polyester~small-pore or medium pore zeolite admixture wherein the zeolite is present in a critical amount of 500 to 1000 parts per million based on the weight of the polyester.
BACKGROUND OF THE INVENTION
Polyesters such as polyethylene terephthalate (PET) are widely used for the production of light weight plastic articles since PET is excellent in mechanical properties such as formability and creep resistance and can be biaxially molecularly oriented. However, during molding or extrusion processes, acetaldehyde is formed by thermal decomposition of the polyester and when the polyester is formed into an article, the acetaldehyde in the article walls migrates into the contents of the article. Small amounts of acetaldehyde adversely affect the flavor retaining property of foods and beverages, and the fragrance retaining property of foods, beverages, cosmetics, and other package contents. For these reasons, it is desirable to minimize the migration of acetaldehyde into package contents.
The use of zeolites in polyesters is disclosed in U.S. Pat. Nos. 3,876,608, 4,391,971 and 5,104,965, and PCT International Publication No. WO 90/03408.
U.S. Pat. No. 3,876,608 discloses the addition of 13X or 4A zeolite in polyesters as a inert filler to increase surface roughness of polyester films. In this disclosure, the molten polymer film is contacted with a AMENDED S~lEET
IPEA/EP
- ~163~60 cooling quench drum to obtain amorphous polymer prior to biaxial orientation. Acetaldehyde is not mentioned.
U.S. Pat. No. 4,391,971 discloses a method for reducing the acetaldehyde content in PET by passing the PET through a bed of zeolite pellets. In this disclosure, the zeolite is not admixed with the polyester.
U.S. Pat. No. 5,104,965 discloses a process for preparing a crystalline polyethylene terephthalate which contains greater than 1000 ppm of a zeolite. No mention is made of acetaldehyde or haze. In contrast, the present inventors have determined that a polyester~zeolite admixture wherein the zeolite is present in a critical amount of 500 parts per million (ppm) to 1000 ppm imparts adequate reduction in residual acetaldehyde without imparting haze to the polyester and thus improves the storage property, flavor retaining property, and fragrance retaining property of containers made from such polyesters. If smaller amounts of zeolite is used, an acceptable level of haze can be achieved, however, residual acetaldehyde is very large.
On the other hand, if larger amounts of zeolite is used, residual acetaldehyde can be reduced but only at the expense of haze.
PCT International Publication No. WO 90~03408 discloses a process for making oriented PET film containing zeolites as slip additives. The use of zeolites as polymerization catalysts in PET is also disclosed. No mention is made of bottle or sheet applications, only oriented film primarily for magnetic tape applications. Acetaldehyde was not mentioned.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to reduce acetaldehyde contained in a polyester and AMENDED SHEET
IPEA/EP
3~6~
improve the flavor retaining property and fragrance retaining property of contents in a vessel formed from the polyester without imparting haze to the polyester.
Another object of the invention is to provide polyester/zeolite admixtures which exhibit excellent mechanical properties such as impact resistance, stress crack resistance and heat resistance, and which display excellent melt flowability at the time of molding thereof, and to provide processes for preparing said polyester~zeolite admixture.
These and other objects are accomplished herçin by a heat-molded or draw-formed plastic article having improved flavor retaining properties and clarity which comprises a thermoplastic polyester~zeolite composition comprising:
(1) a polyester which comprises (a) a dicarboxylic acid selected from the group consisting of aromatic dicarboxylic acids, saturated aliphatic dicarboxylic acids, cycloaliphatic dicarboxylic acids, and combinations thereof, and (b) a diol component comprising repeat units from at least 50 mole percent ethylene glycol, based on 100 mole percent dicarboxylic acid and 100 mole p-ercent diol; and (2) 500 to 1000 parts per million based on the weight of the polyester of a small-pore or medium pore zeolite.
AM~ E :) SHEET
IPEA/~P
- 21~6q DESCRIPTION OF THE-INVENTION
The polyester, component (1), of the present invention includes copolyesters. The polyester may be crystalline, semi-crystalline or amorphous. The polyester contains repeat units from a dicarboxylic acid and a diol, based on 100 mole percent dicarboxylic acid and 100 mole percent diol. Dicarboxylic acids useful in the present invention include aromatic dicarboxylic acids preferably having 8 to 14 carbon atoms, saturated aliphatic dicarboxylic acids preferably having 4 to 12 carbon atoms, and cycloaliphatic dicarboxylic acids preferably having 8 to 12 carbon atoms. Specific examples of dicarboxylic acids are: terephthalic acid, phthalic acid, isophthalic acid, naphthalene-2,6-dicarboxylic acid, cyclohexanedicarboxylic acid, cyclohexanediacetic acid, diphenyl-4,4'-dicarboxylic acid, succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, and the like. The polyester may be prepared from two or more of the above dicarboxylic acids.
It should be understood that use of the corresponding acid anhydrides, esters, and acid chlorides of these acids is included in the term "dicarboxylic acid".
The diol component contains repeat units from at least 50 mole percent ethylene glycol. Examples of diol comonomers which can be included with ethylene glycol are cycloaliphatic diols preferably having 6 to 15 carbon atoms or aliphatic diols preferably having 3 to 8 carbon atoms. Specific diol comonomers are: 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-methylpentanediol-(1,4), 2,2,4-trimethylpentane-diol-(1,3), 2-ethylhexanediol-(1,3), 2,2-diethylpropane-ND~l~ S~ T
~p.-~'~Ft - - 21 B3~
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. The polyester may be prepared from one or more of the above diols.
- The polyester may also contain small amounts of trifunctional or tetrafunctional comonomers such as trimellitic anhydride, trimethylolpropane, pyromellitic dianhydride, pentaerythritol, and other polyester forming polyacids or polyols generally known in th,e art.
For the purposes of the present invention, the preferred polyester composition contains a dicarboxylic acid component which consists essentially of repeat units from terephthalic acid and a diol component which consists essentially of repeat units from ethylene glycol.
Polyesters useful as component (1) have an inherent viscosity of 0.4 to 1.5 dL~g. Preferably, the polyester has an inherent viscosity of 0.6 to 1.2 dL~g as measured at 25C. using 0.50 grams of polymer per 100 ml of a solvent consisting of 60% by weight phenol and 40% by weight tetrachloroethane. The polyester may be prepared by conventional polycondensation procedures well-known in the art. Such processes include direct condensation of the dicarboxylic acid(s) with the diol(s) or by ester interchange using a dialkyl dicarboxylate. For example, a dialkyl terephthalate such as dimethyl terephthalate is ester interchanged with the diol(s) at elevated temperatures in the presence of a catalyst.
The second component of the present invention is a zeolite. Zeolites are crystalline alumino-silicates with highly ordered crystalline structure. Cavities of a defined size are formed in the rigid, three-dimensional network composed of sio4 - and AMENDED SHEET
IPEAIEP
Z163~60 A104-tetrahedra. The lattice contains cavities of varying diameters, depending on the type of zeolite. A
distinction is made between large-, medium-, and small-pore zeolites. In the case of large-pore Y-zeolites, for example, a cavity of this type having a diameter of 7.4 angstroms is formed by twelve sio4 tetrahedra. In the case of small-pore A-zeolites, eight tetrahedra form a ring of diameter 4.1 angstroms. The medium-pore pentasil zeolites have a 10-ring system with an ellipsoidal tubular diameter of 5.5 angstroms x 5.6 angstroms. All medium-pore zeolites are penta,sil zeolites which contain uniform channels. Small-pore and medium-pore zeolites are suitable for use in this invention. Examples of small-pore zeolites include A-zeolites such as 3A, 4A, and 5A, mordenite (small-pore type) such as zeolites sold under the trademarks AW-300 and ZEOLON-300 which are available from Union Carbide and Norton Company, erionite, chabazite, zeolite F such as IONSIV F80, and zeolite W such as IONSIV W85.
IONSIV is a registered trademark of Union Carbide.
Examples of medium-pore zeolites include ZSM-5, ZSM-11, ZSM-22, NU-10, Theta 1, ZSM-23, ZSM-48, TS-l, and silicalite.
The present inventors have determined that addition of small- or medium-pore zeolites in the range of 500 to 1000 parts per million (ppm) based on the weight of the polyester to the polyester, component 1, reduces the concentration of acetaldehyde in the polyester without producing haze and thus improves the storage property, flavor retaining property, and fragrance retaining property of containers made from such polyester.
The polyester compositions of this invention are prepared by mixing a polyester with small- or medium-pore zeolites. The zeolites can be readily incorporated into the polyester during the AMENDE~ SHEET
IPEA~EP
-- ~163~60 polymerization of the polyester or in a later step by any suitable melt blending process such as batch mixing, single screw, or twin screw extrusion. Preferably, the zeolite is added during polymerization since this method produces less haze then melt blending. Because zeolites can absorb and release large amounts of water and hence contribute to polymer hydrolysis on melt blending, it is preferable to dehydrate the zeolites by heating to a temperature of greater than 350C. before adding the zeolites to the polyester melt.
This invention is useful for various packagi,ng applications. Examples include, but are not limited to, thermoformed or injection molded trays, thermoformed or injection molded cups, extrusion blow molded bottles, injection stretch blow molded bottles, extruded film, and extruded sheet.
The materials and testing procedures used for the results shown herein are as follows:
Acetaldehyde ge~eration (AA Gen) was determined by the following method. After crystallizing for 30 minutes at 180C., the pelletized polyester~zeolite admixture was dried overnight at 120C. in a vacuum oven. A Tinius-Olsen melt indexer was loaded with 5 grams of the polyester or copolyester and held at the test temperature (preferably 275-310C.) for five minutes. The molten polyester was extruded into water and stored at a temperature of -25C. until grinding.
The sample was ground to 20 mesh or finer and 0.5 grams was placed in a sample tube which was immediately sealed. The sample was analyzed by dynamic headspace gas chromatographic analysis using a Hewlett-Packard 5890 Gas Chromatograph with a Perkin Elmer Automatic Thermal Desorption ATD-50 as the injection system.
Acetaldehyde was desorbed by heating the sample at AMENDED S~IEET
IPEA/~P
-~163~6~
150C. for ten minutes. The gas chromatography column had a 30 m by 0.53 mm inside diameter.
Haze was determined by ASTM D1003. Haze values of less than 10% are acceptable for high quality packaging.
The invention will be further illustrated by a consideration of the following examples, which are intended to be exemplary of the invention. All parts and percentages in the examples are on a weight basis unless otherwise stated.
Poly(ethylene terephthalate) was prepared by the following procedure.
Dimethyl terephthalate, 145.5 grams, and 93.0 grams of ethylene glycol were placed in a polymerization reactor along with titanium tetraisopropoxide (20 ppm Ti), manganese acetate (55 ppm Mn), antimony oxide (225 ppm Sb), and cobalt acetate (75-ppm Co). The amount and type of zeolite indicated in Table I was also added.
The mixture was heated with stirring under nitrogen atmosphere at 200 C. for 60 minutes, followed by 220 C. for 60 minutes at which time ZONYL A,-(120 ppm phosphorus) which is available from DuPont, was added.
The reaction temperature was increased to 285 C. and pressure was reduced to 0.3 mm Hg (0.3 torr). When the polymer viscosity reached the desired level, the polymerization was terminated by removing the heat source and venting the reactor to ambient pressure. The resulting polyesters had inherent viscosities of O.50-0.68 dL/g. These polyesters were solid-state polymerized to an inherent viscosity of 0.70-0.72 dL/g.
.9MENDFD S~EI~T
IP~
-TABLE I
ZEOLITE AA GEN HAZE
EXAMPLE (type) (ppm) 275C. 295C. (%) 1 NONE 5.413.4 4.43 2 4A 100 4.311.3 7.25 3 3A 500 4.612.1 6.20 4 13X 500 6.216.6 8.11 3A 500 4.413.0 8.43 6 ALUMINA500 5.412.9 5.72 7 3A 500 4.314.5 6.74 8 SILICA500 6.211.7 6.41 9 ALUMINA500 6.112.8 8.15 4A 5000 2.39.6 44.20 11 4A 500 3.611.2 4.34 12 4A 1000 3.48.4 7.48 13 NONE - 7.419.1 3.20 14 4A 2000 3.716.1 17.97 The results in Table I clearly indicate that addition of small- or medium-pore zeolites, as opposed to using large-pore zeolites such as 13X or similar inorganic materials such as alumina and silica, in the range of 100 to 1000 ppm to a polyester reduces the concentration of acetaldehyde in the polyester without producing an unacceptable level of haze. An unacceptable level of haze has been defined as being greater than 10%.
Poly(ethylene terephthalate) was prepared by the following procedure.
Bis(2-hydroxyethyl) terephthalate, 190.5 grams, was placed in a polymerization reactor along with antimony oxide (225 ppm Sb), cobalt acetate (65 ppm Co) and ZONYL A (80 ppm phosphorus). The amount and type of zeolite indicated in Table II was also added. The mixture was heated with stirring under nitrogen atmosphere to 285 C. and pressure was reduced to 0.3 torr. When the polymer viscosity reached the ,s ~I,~T
3~ ~
desired level, the polymerization was terminated by removing the heat source and venting the reactor to ambient pressure. The resulting polyesters had inherent viscosities of 0.57-0.62 dL~g. These polyesters were solid-state polymerized to an inherent viscosity of 0.70-0.72 dL/g.
TABLE II
ZEOLITE AA GEN HAZE
EXAMPLE (type)(ppm) 275C. 295C. (%) NONE - 2.7 10.52.34 16 NONE 3.7 12.93.28 17 4A 100 3.4 14.03.12 18 4A 250 2.3 14.13.04 19 4A 250 2.5 13.73.49 4A 500 2.5 13.38.03 21 4A 1000 2.5 13.610.47 22 4A 1000 2.3 15.76.51 23 4A 2000 2.1 11.413.54 24 4A 5000 1.7 10.940.18 NONE 3.2 13.02.74 The results in Table II clearly indicate that addition of small- or medium-pore zeolites in the range of 100 to 1000 ppm to a polyester reduce the concentration of acetaldehyde in the polyester without producing an unacceptable level of haze, as compared to polyester compositions without zeolites. The addition of small- and medium-pore zeolites to the polyester prepared using the catalyst system in Examples 1-14 have a greater effect in reducing the acetaldehyde than adding the same types of zeolites to the polyester used in Examples 15-25 which contain less catalyst metals.
AMENDED SHEET
IP!~ P
2163~
A polyester resin was prepared by mixing powdered 4A zeolite, 0.6 grams, with 599.4 grams of KODAPAK
PET 9921W which is available from Eastman Chemical Company, and extruding~pelletizing in a Brabender extruder at 275C. melt temperature. The zeolite was heated at 500C. for 12 hours and the PET was dried at 150C. for 12 hours. The pelletized polyester~zeolite resin was crystallized by heating at 180C. for 30 minutes and dried in a vacuum oven for 12 hours at 120C.
Acetaldehyde generation was 8.1 ppm at 275C. and 18.1 ppm at 29SC. compared to 11.0 ppm at 275C. and 25.5 ppm at 295C. without the zeolite additive.
A polyester resin was prepared by mixing powdered 4A zeolite, 6.0 grams, with 594.0 grams of KODAPAK PET
9921W and extruding/pelletizing in a Brabender extruder at 275C. melt temperature. The zeolite was heated at 500C. for 12 hours and the PET was dried at 150C. for 12 hours. The pelletized polyester/zeolite resin was crystallized by heating at 180C. for 30 min-and dried in a vacuum oven for 12 hours at 120C.
Acetaldehyde generation was 6.7 ppm at 275C. and 12.7 ppm at 295C. compared to 11.0 ppm at 275C. and 25.5 ppm at 295C. without the zeolite additive.
Many variations will suggest themselves to those skilled in this art in light of the above detailed description. All such obvious modifications are within the full intended scope of the appended claims.
AMENDED S~IEET
IPEA/FP
Claims (4)
1. A heat-molded or draw-formed plastic article having improved flavor retaining properties and clarity which comprises a thermoplastic polyester/zeolite composition comprising:
(1) a polyester which comprises (a) a dicarboxylic acid selected from the group consisting of aromatic dicarboxylic acids, saturated aliphatic dicarboxylic acids, cycloaliphatic dicarboxylic acids, and combinations thereof, and (b) a diol component comprising repeat units from at least 50 mole percent ethylene glycol, based on 100 mole percent dicarboxylic acid and 100 mole percent diol; and (2) 500 to 1000 parts per million based on the weight of the polyester of a small-pore or medium pore zeolite.
(1) a polyester which comprises (a) a dicarboxylic acid selected from the group consisting of aromatic dicarboxylic acids, saturated aliphatic dicarboxylic acids, cycloaliphatic dicarboxylic acids, and combinations thereof, and (b) a diol component comprising repeat units from at least 50 mole percent ethylene glycol, based on 100 mole percent dicarboxylic acid and 100 mole percent diol; and (2) 500 to 1000 parts per million based on the weight of the polyester of a small-pore or medium pore zeolite.
2. The plastic article according to Claim 1 wherein the zeolite is selected from the group consisting of A-zeolites, erionite, chabazite, small-pore type mordenite, zeolite F, zeolite W, ZSM-5, ZSM-11, ZSM-22, NU-10, Theta 1, ZSM-23, ZSM-48, and TS-1.
3. The plastic article according to Claim 1 wherein the dicarboxylic acid component consists of repeat units from terephthalic acid, and the diol component consists of repeat units from ethylene glycol.
4. The plastic article according to Claim 2 wherein the A-zeolite is selected from the group consisting of 3A, 4A, and 5A.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US7201593A | 1993-06-07 | 1993-06-07 | |
| US08/072,015 | 1993-06-07 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2163660A1 true CA2163660A1 (en) | 1994-12-22 |
Family
ID=22105028
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002163660A Abandoned CA2163660A1 (en) | 1993-06-07 | 1994-05-26 | Polyester/zeolite admixtures |
Country Status (6)
| Country | Link |
|---|---|
| EP (1) | EP0702705A1 (en) |
| BR (1) | BR9406752A (en) |
| CA (1) | CA2163660A1 (en) |
| CZ (1) | CZ320195A3 (en) |
| PL (1) | PL311882A1 (en) |
| WO (1) | WO1994029378A1 (en) |
Families Citing this family (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6337046B1 (en) | 1997-12-22 | 2002-01-08 | Eastman Chemical Company | Process for producing containers from polymer/platelet particle compositions |
| DE10020621A1 (en) * | 2000-04-27 | 2001-11-08 | Degussa | Colorless, low-emission polymer |
| US7041350B1 (en) * | 2002-08-30 | 2006-05-09 | The Coca-Cola Company | Polyester composition and articles with reduced acetaldehyde content and method using hydrogenation catalyst |
| US20040146674A1 (en) * | 2003-01-29 | 2004-07-29 | Howell Earl Edmondson | Acetaldehyde scavenging by addition of active scavengers to bottle closures |
| US6911523B2 (en) * | 2003-07-17 | 2005-06-28 | Colormatrix Corporation | Method to decrease the aldehyde content of polyesters |
| DE102004054182C5 (en) * | 2003-12-12 | 2015-03-12 | Leica Camera Ag | Binocular binoculars with integrated laser rangefinder |
| US6958405B2 (en) * | 2004-03-09 | 2005-10-25 | Arco Chemical Technology, L.P. | Polymer-encapsulated titanium zeolites for oxidation reactions |
| DE102013013163A1 (en) | 2013-07-18 | 2015-01-22 | Kautex Textron Gmbh & Co. Kg | Multilayer composite material and articles comprising same |
| DE102014010129A1 (en) | 2014-07-09 | 2016-01-14 | Kautex Textron Gmbh & Co. Kg | Storage container for receiving an aqueous urea solution |
| EP3047969B1 (en) | 2015-01-22 | 2018-04-25 | Kautex Textron Gmbh&Co. Kg | Multi-layer composite material and articles comprising the same |
| CN113214616B (en) * | 2021-06-15 | 2022-07-12 | 万华化学（宁波）有限公司 | Low-odor biodegradable PLA alloy applied to food contact field and preparation method thereof |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3876608A (en) * | 1972-05-26 | 1975-04-08 | Du Pont | Thermoplastic films containing spherical inorganic particles of 2 to 10 micron size |
| US4391971A (en) * | 1981-12-28 | 1983-07-05 | The Goodyear Tire & Rubber Company | Color improvement and acetaldehyde reduction in high molecular weight polyesters |
| JPS6270442A (en) * | 1985-09-24 | 1987-03-31 | Diafoil Co Ltd | Polyester composition |
| WO1990003408A1 (en) * | 1988-09-30 | 1990-04-05 | E.I. Du Pont De Nemours And Company | Improved process for manufacture of polyethylene terephthalate film containing slip additive |
| US5104965A (en) * | 1991-02-22 | 1992-04-14 | Eastman Kodak Company | Process for the preparation of crystalline poly(ethylene terephthalate) |
| US5187216A (en) * | 1991-04-18 | 1993-02-16 | Eastman Kodak Company | Process for the preparation of crystalline copolyesters |
| WO1993021264A1 (en) * | 1992-04-14 | 1993-10-28 | Eastman Kodak Company | Composition of copolyester and a zeolite |
-
1994
- 1994-05-26 PL PL94311882A patent/PL311882A1/en unknown
- 1994-05-26 EP EP94918113A patent/EP0702705A1/en not_active Withdrawn
- 1994-05-26 WO PCT/US1994/005851 patent/WO1994029378A1/en not_active Application Discontinuation
- 1994-05-26 CA CA002163660A patent/CA2163660A1/en not_active Abandoned
- 1994-05-26 BR BR9406752A patent/BR9406752A/en not_active Application Discontinuation
- 1994-05-26 CZ CZ953201A patent/CZ320195A3/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| PL311882A1 (en) | 1996-03-18 |
| WO1994029378A1 (en) | 1994-12-22 |
| BR9406752A (en) | 1996-02-27 |
| EP0702705A1 (en) | 1996-03-27 |
| CZ320195A3 (en) | 1996-05-15 |
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