KR100535275B1 - Polyester Article - Google Patents

Abstract

The present invention relates to polyester articles comprising polyester polymers produced using catalysts obtainable by the reaction of alkyl titanates or alkyl zirconates, alcohols, 2-hydroxy carboxylic acids and bases. This article preferably takes the form of a film or bottle. The invention also relates to a method of making this article.

Description

Polyester Article {Polyester Article}

<Example 1>

The catalyst was prepared by dissolving citric acid monohydrate (132.5 g, 0.63 mol) in hot water (92.8 g) in a 1 L fish tank flask equipped with a stirrer, condenser and thermometer. Tetraisopropyl titanate (72.0 g, 0.25 mol) was slowly added to the stirred solution with a dropping funnel. The mixture was heated to reflux for 1 hour to obtain an opaque solution from which the isopropanol / water mixture was distilled off under reduced pressure. The product was cooled to below 70 ° C. and 32% weight / weight aqueous NaOH solution (94.86 g, 0.76 mol) was slowly added to the stirred solution with a dropping funnel. The resulting product was filtered, mixed with ethylene glycol (125.54 g, 2.0 mol) and heated under reduced pressure to remove isopropanol / water to give a slightly clear pale yellow product (Ti content 3.85 wt%).

Polyethylene terephthalate (PET) polymers were prepared using a batch route based on terephthalic acid. The esterification vessel was filled with 2250 kg of terephthalic acid, 1050 L of ethylene glycol, 50 ppm of NaOH and 1920 ppm of a solution of the titanium catalyst prepared above (80 ppm of Ti atom). This mixture was heated to 265 ° C. until all the water produced by the reaction was distilled off. 155 ppm of phosphoric acid stabilizer was then added and the reaction mixture was transferred to an autoclave. 300 ppm of cobalt acetate tetrahydrate was added and the reaction mixture was heated to 295 ° C. and melt polymerized under reduced pressure. The resulting PET polymer had an intrinsic viscosity (IV) of 0.685 (measured by solution viscosity for 8% solution of polyester in o-chlorophenol at 25 ° C.) and showed no signs of catalyst haze in the dark field analysis. It was transparent like glass.

Samples of the prepared PET polymers were extruded onto the molten web on the polished surface of the rotating drum cooled from the slot die in a conventional manner and quenched the web below the glass transition temperature of the polyester to provide an amorphous film. The quenched film was then reheated and stretched about 3.2 times its original length in the longitudinal direction, passed through a stenter oven, stretched the sheet to about 3.8 times its original area in the transverse direction, and then thermally cured. The final film thickness was 125 μm. The wide angle haze of the film was 0.51% (measured according to standard ASTM D 1003-61).

<Example 2>

The catalyst was prepared as described in Example 1.

Polyethylene terephthalate (PET) polymers were prepared using a batch route based on terephthalic acid. The esterification vessel was filled with 59.3 kg terephthalic acid, 1.2 kg isophthalic acid, 26 L ethylene glycol and a solution of the titanium catalyst prepared above (providing 24 ppm Ti atom). The mixture was heated to 265 ° C. until all the water produced by the reaction was distilled off. Phosphoric acid stabilizer was then added (provided 13.2 ppm of P atom) and the reaction mixture was transferred to an autoclave. At this time, cobalt acetate tetrahydrate colorant in ethylene glycol was added to give 35.9 ppm of Co atom. The reaction mixture was then heated to 280-290 ° C. and melt polymerized under reduced pressure. The resulting PET polymer showed no signs of catalyst haze in the dark field analysis and was transparent like glass (measured using the final torque of the autoclave stirrer at 40 rpm) and had an IV of about 0.63 and was made into a film. It was suitable. The chromaticity of the polymer was also measured with Colorgard System 45 using the Hunter scale (lh, ah, bh). The following results were obtained.

lh = 47.12; ah = 6.05; bh = 0.19.

<Example 3>

The catalyst was prepared as described in Example 1.

Polyethylene terephthalate (PET) polymers were prepared using a batch route based on terephthalic acid. The esterification vessel was filled with 59.3 kg terephthalic acid, 1.2 kg isophthalic acid, 26 L ethylene glycol and a solution of the titanium catalyst prepared above (providing 24 ppm Ti atom). The mixture was heated to 265 ° C. until all the water produced by the reaction was distilled off. Phosphoric acid stabilizer was then added (provided 13.2 ppm of P atom) and the reaction mixture was transferred to an autoclave. The reaction mixture was then heated to 280-290 ° C. and melt polymerized under reduced pressure. The resulting PET polymer showed no signs of catalyst haze in the dark field analysis and was transparent like glass (measured using the final torque of the autoclave stirring arm at 40 rpm) and produced an IV of about 0.63. It was suitable for. The chromaticity of the polymer was also measured with ColorGuard System 45 using the Hunter scale (lh, ah, bh). The following results were obtained.

lh = 66.74; ah = -1.69; bh = 15.34.

<Example 4>

The catalyst was prepared as described in Example 1.

Polyethylene terephthalate (PET) polymers were prepared using a batch route based on terephthalic acid. The esterification vessel was filled with 59.3 kg terephthalic acid, 1.2 kg isophthalic acid, 26 L ethylene glycol and a solution of the resulting titanium catalyst (providing 7.5 ppm Ti atom). The mixture was heated to 265 ° C. until all the water produced by the reaction was distilled off. Phosphoric acid stabilizer was then added (giving 2.4 ppm of P atoms) and the reaction mixture was transferred to an autoclave. The reaction mixture was then heated to 280-290 ° C. and melt polymerized under reduced pressure. The resulting PET polymer showed no signs of catalyst haze in the dark field analysis and was transparent like glass (measured using the final torque of the autoclave stirring arm at 40 rpm) and produced an IV of about 0.63. It was suitable for. The chromaticity of the polymer was also measured with ColorGuard System 45 using the Hunter scale (lh, ah, bh). The following results were obtained.

lh = 67.9; ah = -0.78; bh = 18.49.

<Example 5>

The catalyst was prepared as described in Example 1.

Polyethylene terephthalate (PET) was prepared using a batch route based on terephthalic acid. The esterification vessel was filled with 60.5 kg of terephthalic acid and 26 L of ethylene glycol. The mixture was heated to 265 ° C. until all the water produced by the reaction was distilled off. Then, trinonylphenyl stabilizer phosphite was added (provided 13.6 ppm of P atoms), and once mixed well, a solution of the prepared titanium catalyst (provided 30 ppm of Ti atoms) was added. This reaction mixture was then transferred to an autoclave, heated to 280-290 ° C. and melt polymerized under reduced pressure. The resulting PET polymer was slightly milky in appearance, exhibited an IV of about 0.63 (as measured using the final torque of the autoclave stirring arm at 40 rpm) and was suitable for making into a film. The chromaticity of the polymer was also measured with ColorGuard System 45 using the Hunter scale (lh, ah, bh). The following results were obtained.

lh = 66.43; ah = -2.03; bh = 20.82.

<Example 6>

750 g of the PET polymer prepared in Example 1 was polymerized in the solid state at 213 ° C. under a flow of nitrogen to obtain a PET polymer having an IV of about 0.82 as measured by a melt viscometer. This polymer was then bottled using injection stretch blow molding techniques.

<Examples 7 to 12>

The catalyst was prepared as described in Example 1.

A series of polyethylene terephthalate (PET) polymers were prepared using a batch route based on terephthalic acid. The esterification vessel was filled with 59.3 kg terephthalic acid, 1.2 kg isophthalic acid, 26 L ethylene glycol and a solution of the resulting titanium catalyst (with varying amounts of catalyst in each example). The mixture was heated to 265 ° C. until all the water produced by the reaction was distilled off. Phosphoric acid stabilizer was then added (in varying amounts for each example) and the reaction mixture was transferred to an autoclave. For some examples, a colorant in ethylene glycol was added (in varying amounts for each example). The reaction mixture was then heated to 295 ° C. and melt polymerized under reduced pressure. The resulting PET polymer showed no signs of catalyst haze and was clear from dark field analysis and showed an IV of about 0.6 as measured by a melt viscometer. Colors of the various polymers were measured with ColorGuard System 45 in CIE units (L ^* , a ^* , b ^* ) using Hunter scales (lh, ah, bh). Information on the amount of titanium catalyst, phosphate stabilizer and colorant, as well as the results are listed in Tables 1 and 2 below.

Example number Ti ppm P ppm Colorant IV L ^* a ^* b ^* lh ah bh 7 15 9.7 none 0.61 74.9 -1.85 19.1 69.3 -1.71 15.7 8 7.5 4.8 none 0.6 80.6 -2.48 12.2 76.0 -2.36 10.8 9 11.25 7.3 none 0.61 78.9 -1.88 19.3 73.3 -1.76 16.2

Example number Ti ppm P ppm Co ¹ ppm Red Dye ppm ² Blue dye ppm ² L ^* a ^* b ^* lh ah bh 10 7.5 4.8 30.8 - - 63.2 5.58 -3.09 56.4 4.91 -2.74 11 7.5 4.8 - 2 5 55.5 6.36 -12.3 48.4 5.34 -11.2 12 24 13.2 31.4 - - 54.6 8.75 -3.88 47.5 7.36 -3.28 ¹ Co is added as cobalt acetate tetrahydrate in ethylene glycol. ² Red and blue dyes, Estofil SFBL® and Estorfil SRBL® are commercially available from Clariant UK, respectively. These dyes are added as a solution in ethylene glycol.

The polymer was then polymerized in a solid state at 210 ° C. under a flow of nitrogen to give a PET polymer having an IV of about 0.82 as measured by a melt viscometer. In Examples 7, 8 and 9, samples of the PET polymer obtained after the solid state polymerization were made into a plate having a diameter of 100 mm and a thickness of 4 mm, and then the haze value of the polymer plate was measured using a Gardner Pivotable Sphere Hazemeter. . Haze values of 1.8, 1.6 and 2.2 were obtained for the polymers of Examples 7, 8 and 9. Finally, the PET polymer obtained after the solid state polymerization in Examples 7-11 was bottled using the injection stretch blow molding technique. In addition, the final polymer of Example 12 was also suitable for bottle making.

Comparative Example 1

To prepare the polyester, the process of Example 1 was repeated except that 250 ppm of tetraisopropyl titanate (40 ppm Ti atom) was used as catalyst. The wide angle haze of the resulting film was 1.35%.

The present invention relates, in particular, to polyester articles in the form of films or containers, more particularly polyester articles comprising polyesters produced using specific titanium or zirconium catalysts.

The use of polyesters, in particular polyethylene terephthalate or copolymers thereof (commonly referred to as polyethylene terephthalate or PET), for the production of packaging materials such as films, bottles and other containers is well known. In the case of bottles for containing beverages such as carbonated soft drinks and mineral water, they are usually prepared from polyester in the form of polymer chips, using a two-step process. In the first step of the process, the bottle preform is prepared by injection molding the polyester, and in the second step, the bottle preform is heated at a suitable temperature, for example using infrared light, and then the final shape of the bottle Blow into the formwork using compressed air. Blow molding processes cause biaxial stretching of the polyester in certain areas of the bottle, such as the cylindrical wall, thereby imparting greater strength to the bottle, allowing it to withstand deformation during use. A preferred blow molding process is a stretch blow molding process in which the inner mandrel moves along its axis toward the preform before and / or at the same time injecting compressed air to promote axial stretching of the bottle preform.

It is well known to prepare polyesters in a two-step process. In the first step, glycols and dicarboxylic acids are reacted (directly esterified) or, alternatively, alkyl esters of glycols and dicarboxylic acids are reacted (esters at elevated temperatures in the range from 150 to 285 ° C. Exchange or transester reaction) 'monomers' are prepared. Catalysts such as manganese acetate or zinc acetate are commonly used in the transesterification reaction, while direct esterification can be carried out without catalyst. In the second stage of polyester production, monomer molecules are condensed with each other by heat in the presence of a catalyst (polycondensation). Glycol is produced during the condensation reaction and is removed under reduced pressure. Various polycondensation catalysts such as antimony trioxide, germanium dioxide and zinc acetate have been commonly used.

The most commonly used method for producing PET for conversion into bottles or other containers is the compound bis (2) by reaction of ethylene glycol with a dialkyl terephthalate ester such as terephthalic acid or dimethyl terephthalate. -Hydroxyethyl) terephthalate, comprising the step of preferentially preparing a low molecular weight oligomer which generally corresponds to. Typically, this oligomer is prepared by esterifying terephthalic acid with ethylene glycol at a molar ratio of 1: 1.05 to 1: 2.5, typically 1: 1.15 to 1: 1.3, at about atmospheric pressure and a moderately elevated temperature, such as 270 ° C. . Water is produced during the esterification reaction and removed by distillation together with co-distilled ethylene glycol. The resulting oligomers comprise a mixture of compounds believed to include monoesters, bis (2-hydroxyethyl) terephthalate diesters and low molecular weight oligomers. The average degree of polymerization (named the number of ethylene terephthalate residues in the oligomer) of the mixture is typically 2.5 to 10.0. This oligomer is generally referred to as bis (2-hydroxyethyl) terephthalate or simply using the term 'monomer', which term will be used below.

This monomer is then polymerized in a molten state at elevated temperature, typically 250-300 ° C. and partial vacuum, to give a medium molecular weight polymer (commonly referred to as a prepolymer). This melt phase polymerization or polycondensation step results in the production of ethylene glycol and water, which are continuously removed during the polymerization reaction until a prepolymer having an intrinsic viscosity (IV) in the range of about 0.50 to 0.68 dl / g is formed. Continues. When the IV of the prepolymer reaches the desired value, the molten prepolymer is extruded into a lace form, quenched and cut into pellet shapes. These pellets are usually amorphous polymers because of the rapid cooling process.

The prepolymer pellets are then subjected to a solid state polymerization comprising heating the pellets at a temperature of about 210 to 240 ° C., typically under partial vacuum or under a flow of inert gas. Solid state polymerization can be carried out in a fluidized bed reactor, in a tumbling chip reactor, or in a continuous working fixed bed reactor and typically continues until the IV of the polymer is between about 0.7 and 0.9 dl / g.

As mentioned above, the prepolymer pellets produced in the melt phase polymerization process are amorphous and tend to self-stick and stick to each other at temperatures of the degree necessary to exhibit a satisfactory polymerization rate in the solid state. To avoid this problem, the amorphous prepolymer pellet is usually crystallized by heating the pellet to a temperature slightly below the temperature in the solid state polymerization before the solid state polymerization. Since the crystalline prepolymer softens at a higher temperature than the amorphous material, there is no problem that the prepolymer pellets stick to each other at the temperature in the solid state polymerization process.

Titanium compounds such as alkyl titanates have been used as polyester catalysts for both monomer formation and polycondensation. Unfortunately, titanium catalysts often cause the production of polymers that exhibit relatively high haze and precipitation of inorganic titanium compounds such as titanium dioxide due to the inactivation of the titanium catalyst. As a result, films and containers made from this polymer are often undesirable because of the degree of haze. Deactivation of the above-mentioned titanium catalyst can also cause a decrease in its catalytic efficiency. Moreover, titanium catalysts are often yellow in appearance, producing polymers that are not suitable for making films and bottles. The yellowing of the polymer is particularly undesirable when the polymer is used to make a bottle in which a colorless transparent polymer is desired.

British Patent Publication No. 1421972 relates to the use of alkyl titanates as direct esterification catalysts in the production of polyesters, preferably polyethylene terephthalate.

Japanese Patent Laid-Open No. 6170911 describes a method for producing polyester, in particular polyethylene terephthalate film, using polyester polymerized with 7 to 120 ppm of titanium atom and adding up to 150 ppm of phosphorus atom after polymerization and before melt extrusion. . Japanese Patent Laid-Open No. 6170911 describes reaction products of titanium alcoholates and organic acid salts and tetraalkyl titanates and aromatic polycarboxylic acids or their anhydrides as suitable titanium catalysts.

The inventors now include polyester polymers produced using certain titanium or zirconium catalysts, which can reduce or overcome one or more of the problems mentioned above with respect to titanium catalysts, preferably in the form of films or containers. An ester article was developed.

According to the invention, preferably in the form of a film or a container comprising a polyester polymer produced using an alkyl titanate or an alkyl zirconate, an alcohol, 2-hydroxy carboxylic acid and a catalyst obtainable by reacting a base. It provides a polyester article of.

The present invention also provides a method of making a polyester article that includes the use of a polyester polymer produced using a catalyst obtainable by reacting an alkyl titanate or alkyl zirconate, an alcohol, 2-hydroxy carboxylic acid and a base. To provide.

Examples of polyester articles of the present invention include extruded sheets, tubes and blister / display packs. However, the polyester articles of the present invention preferably take the form of films or containers.

When the polyester article takes the form of a container, it is usually a bottle and is preferably a bottle made from the polyester polymer by an injection blow molding process, in particular an injection stretch blow molding process. Thus, injection blow molded, in particular injection stretch blow molded bottles are a preferred aspect of the present invention.

The present invention also includes preforms that can make bottles, in particular injection molded bottle preforms. Thus, according to another aspect of the invention, polyesters comprising polyester polymers produced using alkyl titanates or alkyl zirconates, alcohols, 2-hydroxy carboxylic acids and catalysts obtainable by reacting bases Bottle preforms are provided.

Injection blow molded bottles are made in a two-step process. In the first step of the process, the bottle preform is produced by injection molding a polyester polymer, and in the second step, the preform is heated to a suitable temperature, for example using infrared light, and then blow molded to form the final bottle product. Make Injection stretch blow molded bottles are prepared in the same manner as injection blow molded bottles, except that the preform is also axially stretched using mandrel before and / or during the blow molding process.

The preform takes the form of a small bottle, typically a cylinder with one end closed, about one third the length of the final bottle and about one quarter the outer diameter of the final bottle. For example, a bottle having a capacity of 1.5 L will typically be about 30 cm in length and about 8 to 12 cm in outer diameter. The intermediate preforms of such bottles typically have a length of about 10 to 15 cm and an outer diameter of about 3 to 4 cm.

Suitable polyester polymers for the manufacture of containers and especially bottles are partially aromatic polyesters and especially polyesters derived substantially from aromatic diacids (or esters thereof) and aliphatic diols (including cycloaliphatic).

Preferred partially aromatic polyesters for making containers, in particular bottles, comprise at least 50 mole%, preferably 70 moles of ethylene terephthalate residues, ie terephthalic acid or its esters such as dimethyl terephthalate, and residues derived from the reaction of ethylene glycol. Mole% or more. The polyester may also contain residues derived from ethylene isophthalate, ethylene naphthalate, ethoxyethylene terephthalate, ethoxyethylene isophthalate or ethoxyethylene naphthalate.

Particularly preferred partially aromatic polyesters for bottle making are, in fact, derived from terephthalic acid (or esters thereof, such as dimethyl terephthalate) and ethylene glycol, inserting aromatic dicarboxylic acid (or esters) units that interfere with chain orientation. Modified polyethylene terephthalate polymers, modified by replacing several terephthalate units provided by terephthalic acid. Aromatic dicarboxylic acids which hinder chain orientation reduce the tendency of the polymer to crystallize under the orientation produced by stretching, so that polyethylene tere based on polyester to be processed into bottles using injection blow molding, in particular injection stretch blow molding techniques. It is advantageous to use in phthalates. Aromatic dicarboxylic acids which interfere with the chain orientation are those in which two carboxyl functional groups are bonded directly to an aromatic, in particular benzene or naphthalene ring, but which do not form a straight line together. The angles between the two carboxyl functional groups deviate considerably at 180 ° C. or together using diacids that are not parallel together as in the 1,5 and 2,6 substitution forms around the naphthalene ring system It can be prevented from forming a straight line. Examples of suitable aromatic dicarboxylic acids that hinder chain orientation include particularly useful isophthalic acid (benzene-1,3-dicarboxylic acid), naphthalene-2,6-dicarboxylic acid, 2,2-diphenylpropane -4,4'-dicarboxylic acid, 2,2-diphenylmethane-4,4'-dicarboxylic acid, biphenyl-3,4'-dicarboxylic acid and benzophenone-4,4'- Dicarboxylic acids are included.

The amount of aromatic dicarboxylic acid which interferes with chain orientation, incorporated in the modified polyethylene terephthalate polymer, should, of course, be sufficient to reduce the crystallization tendency of the polymer. The specific amount depends on the specific dicarboxylic acid used, but the proportion of units derived from aromatic dicarboxylic acids that typically impede chain orientation is 1.0 to 12.0 mole% as a percentage of the total dicarboxylic acid derived units in the polymer. It will be in the range, and particularly advantageous results will be obtained using ratios ranging from 1.5 to 4.0 mole%, in particular from 1.8 to 3.0 mole%.

Modified polyethylene terephthalate polymers may also replace some of the common monoethylene glycol residues, including diethylene glycol residues in consumption. The polymerization process used to prepare polyethylene terephthalate for bottle making will typically result in the incorporation of some polyethylene glycol residues, in particular diethylene glycol residues, to lower amounts of triethylene glycol residues in the polymer. In a continuous polymerization process, the proportion of polyethylene glycol residues mixed in the polymer will typically be about 1.5 to 2.5 mole%, based on the total glycol residues in the polymer. (Di-ethylene glycol residues and tri-ethylene glycol residues can be formed by linking chains terminated by esterification of ethylene glycol monomers as well as glycol residues, so that free di-ethylene glycol or tri- is formed during the reaction. Ethylene glycol is not necessarily present. However, if desired, additional diethylene glycol moieties can be incorporated into the polymer by adding diethylene glycol as monomer.

When the polyester article of the present invention is a bottle, the polyester polymer forming the bottle typically has an inherent viscosity in the range of 0.70 to 0.90 (measured for an o -chlorophenol solution of 1% (w / v) polymer at 25 ° C). (IV). A particularly useful IV range is 0.72 to 0.85. Preferred polyester polymers for conversion into bottles will exhibit a haze value of less than 9, in particular less than 8, in particular less than 6. The percentage of light that deviates by an average of more than 2.5 ° forward is measured by using a Gardner Pivotable Sphere Hazemeter for polyester plates 100 mm in diameter and 4 mm thick.

Polyester polymers for bottle making can be made by any method known to those skilled in the art for making bottle polymers, in particular by the most commonly used methods already described herein.

The polyester polymers used in the containers of the present invention may also contain additives such as stabilizers, processing aids, fillers, antioxidants, plasticizers and lubricants which do not adversely affect the polymer. Pigments and / or dyes may also be included to make colored bottles, especially those colored green, amber and brown. If the polymers contain additives, they will usually be incorporated in amounts conventional in the art.

When the polyester article of the present invention takes the form of a polyester film, this film will be a freestanding film, meaning a freestanding structure that can exist independently without a supporting substrate.

Polyesters suitable for use in film formation are preferably synthetic linear polyesters, which are at least one glycol, in particular aliphatic or cycloaliphatic glycols, for example ethylene glycol, 1,3-propanediol, 1,4-butanediol , With neopentyl glycol and 1,4-cyclohexane dimethanol (optionally with monocarboxylic acids such as pivalic acid), one or more dicarboxylic acids or lower alkyl (up to 6 carbon atoms) diesters, For example terephthalic acid, isophthalic acid, phthalic acid, 2,5-, 2,6- or 2,7-naphthalenedicarboxylic acid, succinic acid, sebacic acid, adipic acid, azelaic acid, 4,4'-diphenyl It can obtain by condensing dicarboxylic acid, hexahydro- terephthalic acid, or 1,2-bis-p-carboxyphenoxy ethane. Preference is given to polyethylene terephthalate or polyethylene naphthalate films. As described, for example, in British Patent Publication No. 838708, polyethylene terephthalate films, typically biaxially stretched by continuous stretching in two mutually perpendicular directions at temperatures in the range of 70 to 125 ° C. and are usually Particular preference is given to such polyethylene terephthalate films which are heat cured at temperatures in the range of 150 to 250 ° C.

The polyester film may be stretched or preferably stretched, for example uniaxially stretched, or more preferably biaxially stretched in two mutually perpendicular directions at the film plane to achieve a satisfactory combination of mechanical and physical properties. Can be. Parallel biaxial stretching can be performed by extruding a thermoplastic polymer tube, followed by quenching, reheating, and then expanding by internal gas pressure to draw at a rate that induces lateral stretching and induces longitudinal stretching. Continuous elongation can be performed by the stenter method by extruding thermoplastics as flat extrudates that first elongate continuously in one direction and then in another mutually perpendicular direction. Usually, it is preferred to first stretch in the longitudinal direction, ie in the direction of advancing through the film stretching machine, and then in the transverse direction. The stretched base film can be thermally cured under dimensional limitations, preferably at temperatures above its glass transition temperature to stabilize the dimensions.

If the polyester article of the present invention is a film, the IV of the polyester polymer for making the film usually ranges from 0.5 to 0.8, preferably from 0.6 to 0.65, in particular from 0.61 to 0.63. The polyesters surprisingly exhibit a low IV drop, preferably less than 0.04, more preferably 0.001 to 0.03, in particular 0.005 to 0.002, especially 0.01 to 0.015 when film extruded.

In a particularly preferred embodiment of the invention, the polyester for making the film has a chromaticity "b" value (ie yellow value) in the range of -6 to +6, more preferably -3 to +3, and especially -1 to +2. Indicates.

In a preferred embodiment of the invention, the polyester film is transparent, preferably high optical transparency, and preferably measured according to standard ASTM D 1003-61, for films having a thickness of preferably 125 μm, preferably 3 Low haze with a wide-angle haze of less than%, more preferably less than 1%, especially less than 0.5%, and especially less than 0.2%. The above mentioned optical properties can be suitably achieved by having little or no particulate additive present in the film. The polyester film may contain a relatively small amount of filler material, for example in the range of 5 to 3000 ppm, preferably 50 to 2000 ppm, more preferably 100 to 1000 ppm, to provide handling capability. Suitable fillers include inorganic materials such as silica, clay, calcium carbonate, and organic materials such as silicone resin particles. Spherical monodisperse fillers are preferred.

The thickness of the polyester film according to the invention is preferably in the range from 5 to 350 μm, more preferably from 15 to 250 μm, in particular from 25 to 150 μm, in particular from 75 to 125 μm.

The polyester film according to the invention, in comparison with the component material, is coated with one or both sides with one or more additional coatings, inks, lacquers and / or metal layers, for example to improve handling, antistatic properties and adhesion. Alternatively, a laminate or composite may be formed that exhibits improved properties such as peeling. Suitable coating materials include acrylic resins, copolyesters, styrene copolymers, acrylic copolymers, functionalized polyolefins, film-forming polymeric resins such as polyvinyl alcohol, cellulose materials such as nitrocellulose, ethylcellulose and hydroxyethylcellulose. Include. Blends of mixtures of any of the aforementioned polymeric resins may be used.

Prior to attaching the coating medium to the polyester film, its exposed surface can be chemically or physically surface-modified, if necessary, to enhance the bonding between the surface and the coating layer to be subsequently applied. Preferred treatment is corona discharge. Alternatively, the surface of the polyester film may be prepared by dissolving p-chloro-m-cresol, 2,4-dichlorophenol, 2,4,5- or 2 in halogenated phenols such as acetone or methanol dissolved in conventional organic solvents. It may be pretreated with reagents known in the art having solvent action or swelling action on the film, such as, 4,6-trichlorophenol, or 4-chlororesorcinol.

The coating medium can be applied to the already stretched polyester film surface, but the application of the coating medium is preferably carried out before or during the stretching operation. In particular, it is preferred that the coating medium is applied to the polyester film surface between two stages of the biaxial stretching operation (vertical and reverse).

The polyester film or additional coating layer (s) may conveniently contain any additives commonly used in the manufacture of polymeric films. Thus, additives such as dyes, pigments, foaming agents, lubricants, antioxidants, anti-sticking agents, surfactants, slip aids, gloss enhancers, predegradants, UV stabilizers, viscosity modifiers and dispersion stabilizers may be used to form film-forming (co) polymers and ( Or) in the coating layer medium.

The catalyst used to prepare the polyester polymer from which the polyester article of the present invention is made can be obtained by reacting alkyl titanate or alkyl zirconate, alcohol, 2-hydroxy carboxylic acid and base, preferably Is its reaction product. Alkyl titanate and alkyl zirconate may be used in combination in the preparation of the catalyst if necessary.

In the terms alkyl titanate and alkyl zirconate, we intend to include compounds having substituted alkyl groups. The term also refers to the formula R ¹ O [M (OR ¹ ) ₂ O] _n R ¹ , wherein M is titanium or zirconium, R ¹ is preferably an alkyl group having 1 to 6 carbon atoms, and n is preferably Condensation products, mainly represented by less than 20 and more preferably less than 10). Suitable condensed alkyl titanates and alkyl zirconates include known compounds known as polybutyl titanate, polyisopropyl titanate and polybutyl zirconate.

Preferred alkyl titanates and alkyl zirconates for the preparation of catalysts have the formula M (OR) ₄ where M is titanium or zirconium and R is preferably an alkyl group having 1 to 6 carbon atoms. Preferred alkyl titanates include tetramethyl titanate and tetraethyl titanate, tetrapropyl titanate, tetraisopropyl titanate, tetrabutyl titanate and tetrahexyl titanate. Tetraisopropyl titanate is particularly preferred. Preferred alkyl zirconates include tetraethyl zirconate, tetrapropyl zirconate and tetrabutyl zirconate.

The alcohol preferably comprises at least two hydroxyl groups, more preferably a dihydric alcohol. Suitable dihydric alcohols include 1,2-diols such as ethylene glycol and 1,2-propane diol; 1,3-diol such as 1,3-propane diol; Dihydric alcohols containing longer chains such as diethylene glycol and polyethylene glycol. Suitable polyhydric alcohols include glycerol, trimethylol propane and pentaerythritol. Ethylene glycol and diethylene glycol are preferred alcohols. The molar ratio of alcohol to alkyl titanate or alkyl zirconate is preferably 2: 1 to 12: 1, more preferably 4: 1 to 8: 1.

Preferred 2-hydroxy carboxylic acids include lactic acid, citric acid, malic acid and tartaric acid. Citric acid is particularly preferred. The molar ratio of 2-hydroxy carboxylic acid to alkyl titanate or alkyl zirconate is preferably 1: 1 to 4: 1, more preferably 1.5: 1 to 3.5: 1.

Bases are typically inorganic bases and suitable bases include sodium hydroxide, potassium hydroxide, ammonium hydroxide, sodium carbonate and ammonia. Typically, the amount of base used will be sufficient to completely neutralize the 2-hydroxy carboxylic acid, but this is not essential. For monobasic 2-hydroxy acids, such as lactic acid, the preferred amount of base is in the range of 0.8 to 1.2 moles per mole of 2-hydroxy acid. In the case of citric acid (tribasic acid), the preferred amount of base is in the range of 1 to 3 moles per mole of 2-hydroxy acid. Typically, the molar ratio of base to alkyl titanate or alkyl zirconate is in the range of 1: 1 to 12: 1, preferably 1: 1 to 4: 1.

The catalyst can be prepared by mixing any of its components while removing any by-products in any suitable step. In a preferred method, the alkyl titanate or alkyl zirconate and alcohol are mixed together and then 2-hydroxy carboxylic acid is added first or as a pre-neutralized mixture, 2-hydroxy carboxylic acid and base Is added to this mixture. In another preferred method, alkyl titanate or alkyl zirconate is reacted with 2-hydroxy carboxylic acid and alcohol byproducts are removed. This base is then added to the reaction product and alcohol is added.

The amount of catalyst used in the preparation of the polyester to make the polyester article of the invention depends, among other things, on the titanium or zirconium content of the catalyst and also whether the article is a film or a container. If the article is a container, in particular a bottle, the amount of catalyst used to prepare the polyester polymer is typically 2.5 to 100 ppm, preferably 5 to 75 ppm, more preferably based on the weight of the final resulting polyester polymer. Preferably, it will provide about 7.5 to 50 ppm, in particular 7.5 to 30 ppm of titanium or zirconium atoms. If the article is a film, the amount of catalyst used to prepare the polyester polymer is usually 15 to 120 ppm, preferably 15 to 100 ppm, more preferably based on the weight of the final resulting polyester polymer. 20 to 30 ppm, in particular 24 to 30 ppm of titanium or zirconium atoms.

Mixtures of any two or more titanium and zirconium catalysts described herein can be used to prepare the polyester polymer.

Titanium or zirconium catalysts can serve as catalysts in monomers as well as in esterification or transesterification reactions used to prepare the melt phase and optionally in the subsequent solid state polymerization reactions. Thus, this catalyst may be added prior to monomer formation to catalyze at least the esterification or transesterification reaction and also the subsequent polymerization reaction, or may be added after monomer formation to catalyze only the polymerization reaction. Preferably, this catalyst is added before monomer formation.

In one embodiment of the invention, the polyester from which the polyester article is made is prepared by catalyzing monomer formation using a titanium or zirconium catalyst, preferably by a direct esterification route, and the further catalyst is followed by a polymerization process. Is used to catalyze. Additional catalysts include zinc acetate and antimony and germanium catalysts such as those commonly used in the art such as antimony trioxide and germanium dioxide. Additional catalysts, suitably antimony trioxide, are usually used in amounts of 100 to 500 ppm, preferably 150 to 350 ppm, more preferably 225 to 275 ppm, based on the weight of the final produced polyester. .

Phosphorus stabilizing compounds may also be incorporated into the polyesters. Suitable phosphorus stabilizing compounds include phosphorous acid, phosphinic acid, phosphates and phosphites. Specific examples include phosphorous acid, phosphoric acid, phosphonic acid, sodium dihydrogen phosphate, trisnonyl phosphite, trimethyl phosphate, triethyl phosphate, tributyl phosphate, triphenyl phosphate, diphenyl phosphite, dibutyl phosphite, dimethylphenyl phosphate and ammonium phosphate Included. The phosphorous acid compound is preferably selected from the group consisting of phosphoric acid, phosphorous acid and trisnonylphenyl phosphorous.

The concentration of phosphorus atoms is suitably in the range from 2 to 100, preferably from 2 to 60, more preferably from 2 to 30, in particular from 3 to 20, especially from 10 to 20 ppm, based on the weight of the final polyester.

The phosphorus compound may be added before the monomer formation, but is preferably added after the monomer formation, that is, after the direct esterification or transesterification reaction and before the polycondensation reaction.

The molar ratio of titanium or zirconium atoms to phosphorus atoms is preferably 0.25: 1 to 4: 1, more preferably 0.33: 1 to 3: 1, especially 0.5: 1 to 2: 1, particularly 0.75: 1 to 1.5: 1 range. In a particularly preferred embodiment, the molar ratio of titanium or zirconium atoms to phosphorus atoms is about 1: 0.85.

In a preferred embodiment of the invention, a toning material is added to the reaction mixture to improve the color and clarity of the final polyester. Preferred colorants are cobalt (II) salts such as cobalt acetate and cobalt acetate tetrahydrate, which are 19 to 60 ppm, preferably 27 to 41 ppm, more preferably 31 to 36 ppm based on the weight of the final polyester. It is customary to add in an amount to provide cobalt of. Another suitable colorant is a mixture of red and blue dyes. The red dye is added in an amount of preferably 1 to 15 ppm, more preferably 1 to 10 ppm, particularly preferably 2 to 5 ppm, based on the weight of the polymer. The blue dye is added in an amount of preferably 1 to 20 ppm, more preferably 1 to 15 ppm, particularly preferably 3 to 8 ppm, based on the weight of the polymer.

The colorant is preferably added after the monomer formation, that is, after the direct esterification or transesterification reaction and before the polycondensation reaction. However, the colorant is preferably added after the phosphorus compound.

Sodium hydroxide may also be added to the reaction mixture, preferably at the same time as the titanium or zirconium catalyst, preferably prior to monomer formation, in order to inhibit the formation of diethylene glycol. When sodium hydroxide is mixed into the reaction mixture, the amount to be added will preferably be provided at 40 ppm or less, more preferably 30 ppm or less, particularly preferably 20 ppm or less, based on the weight of the final polyester.

The present invention will now be described with reference to the following examples, but is not limited thereto.

Claims (22)

A process obtainable by reacting an alkyl titanate or an alkyl zirconate, an alcohol, 2-hydroxy carboxylic acid and a base, wherein the alcohol comprises at least two hydroxyl groups. . The process of claim 1, wherein the alkyl titanate or alkyl zirconate has the formula M (OR) ₄ , wherein M is titanium or zirconium and R is an alkyl group of 1 to 6 carbon atoms. The process according to claim 1 or 2, wherein the catalyst comprises the reaction product of alkyl titanate, alcohol, 2-hydroxy carboxylic acid and base. The process according to claim 1 or 2, wherein the alkyl titanate is tetraisopropyl titanate. The process according to claim 1, wherein the alcohol is a dihydric alcohol. The process according to claim 5, wherein the dihydric alcohol is ethylene glycol. The process according to claim 1 or 2, wherein the 2-hydroxy carboxylic acid is citric acid. The production process according to claim 1 or 2, wherein the base is an inorganic base. The method of claim 8, wherein the inorganic base is sodium hydroxide. The process of claim 1 wherein the catalyst is used in an amount that provides 2.5 to 100 ppm of titanium or zirconium atoms in the final resulting polyester polymer based on the weight of the polymer. The process of claim 10 wherein the catalyst is used in an amount that provides 7.5 to 30 ppm titanium or zirconium atoms in the final resulting polyester polymer based on the weight of the polymer. The process of claim 1 wherein the catalyst is used in an amount that provides 15 to 120 ppm of titanium or zirconium atoms in the final resulting polyester polymer based on the weight of the polymer. 13. A process according to claim 12 wherein the catalyst is used in an amount to provide 24 to 30 ppm of titanium or zirconium atoms in the final resulting polyester polymer based on the weight of the polymer. The process according to claim 1 or 2, wherein the polyester polymer comprises 2 to 100 ppm by weight of phosphorus atoms. The process according to claim 1 or 2, wherein the polyester polymer comprises a colorant. The process according to claim 15, wherein the colorant is a cobalt (II) salt. The process of claim 16, wherein the cobalt (II) salt is present in an amount that provides 19 to 60 ppm cobalt based on the weight of the polyester polymer. 18. The process of claim 17, wherein the cobalt (II) salt is present in an amount that provides 31 to 36 ppm cobalt based on the weight of the polyester polymer. The method of claim 15, wherein the colorant is a mixture of red and blue dyes. The process according to claim 1 or 2, wherein the polyester polymer contains up to 40 ppm by weight of sodium. The method of claim 20, wherein the polyester polymer contains 30 weight ppm or less sodium. 3. The process according to claim 1, wherein the polyester polymer has a chromaticity “b” value in the range of −6 to +6. 4.