JP2003252976A - Method for manufacturing polyester, and catalyst for manufacturing polyester - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a polyester excellent in thermal stability. <P>SOLUTION: The method for manufacturing the polyester comprises adding a specific amount of a specific compound such as a polyoxyalkylene glycol to a polycondensation catalyst. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing polyester.

[0002]

2. Description of the Related Art Due to its excellent properties, polyester is widely used in various fields including fibers, films and bottles. Among them, polyethylene terephthalate is preferably used because of its excellent mechanical strength, chemical properties, dimensional stability and the like.

Polyethylene terephthalate is generally produced from terephthalic acid or its ester-forming derivative and ethylene glycol, but in a commercial process for producing high molecular weight polymers, how good is the thermal stability of the polymer? Is one of the important issues. For example, in the case of a polyester having low thermal stability, thermal decomposition remarkably progresses in the polymerization step, and a polymer having a sufficient degree of polymerization cannot be obtained, or even if a predetermined degree of polymerization is obtained, the polymerization is prolonged. There are problems such as time-consuming and intense coloring of the polymer. In addition, the degree of polymerization is drastically reduced even in the molding process, which causes problems such as the inability to obtain a molded product having sufficient mechanical properties and poor process stability.

Although there are various factors that affect the thermal stability of such polymers, one of the main causes is that the polycondensation catalyst used for polymerizing polyesters acts on the thermal decomposition of the polymer. As. That is, while the polycondensation catalyst functions to accelerate the polymerization reaction, it may also accelerate the thermal decomposition reaction of the polymer, and how to suppress the decomposition reaction of the latter while maintaining the catalytic effect of the former is a catalyst design. It can be said that this is an important issue.

As for the polycondensation catalyst, a titanium compound or an aluminum compound has been used in order to avoid problems such as contamination of the die due to the antimony catalyst, as compared with the antimony catalyst which has been used most widely in the past. Studies have been made to use the above as a polycondensation catalyst. For example, WO 95/18839 discloses a composite oxide composed of titanium and silicon, JP 2001-89557 A discloses a titanium compound catalyst obtained by hydrolyzing a titanium halogen compound, and US Pat. No. 5,512,340. Has proposed the use of an aluminum compound as a polycondensation catalyst. However, such titanium or aluminum-based polycondensation catalysts have problems that the thermal stability of the polymer is likely to be lowered, the color tone is deteriorated, and the degree of polymerization is greatly reduced during molding.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a polyester having excellent thermal stability and a catalyst for producing the polyester used in the method.

[0007]

The above-mentioned object of the present invention is a product obtained by an esterification reaction or transesterification reaction between an aromatic dicarboxylic acid or an ester-forming derivative thereof and a diol or an ester-forming derivative thereof. In the method for producing a polyester by polycondensation of at least one compound selected from the group consisting of polyoxyalkylene glycol and its derivative, cyclodextrin and its derivative, calixarene and its derivative, with respect to the compound (A) used as a polycondensation catalyst. A polyester characterized in that one compound (B) is added to the reaction system so that the mixing ratio (A / B) of the compound (A) and the compound (B) on a molar basis is 0.005 to 50. This is achieved by the manufacturing method.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The polyester of the present invention is a polymer synthesized from a dicarboxylic acid or its ester-forming derivative and a diol or its ester-forming derivative, and can be used as a molded article such as a fiber, a film or a bottle. There is no particular limitation as long as it is possible.

Specific examples of such polyesters include polyethylene terephthalate, polypropylene terephthalate, polytetramethylene terephthalate, polycyclohexylene dimethylene terephthalate,
Polyethylene-2,6-naphthalene dicarboxylate
And polyethylene-1,2-bis (2-chlorophenoxy) ethane-4,4′-dicarboxylate. The present invention is suitable for the most commonly used polyethylene terephthalate or a polyester copolymer mainly composed of polyethylene terephthalate.

In addition to diethylene glycol, these polyesters include, as copolymerization components, dicarboxylic acids such as adipic acid, isophthalic acid, sebacic acid, phthalic acid, 4,4'-diphenyldicarboxylic acid and their ester-forming derivatives, and polyethylene. Dioxy compounds such as glycol, hexamethylene glycol, neopentyl glycol, and polypropylene glycol, oxycarboxylic acids such as p- (β-oxyethoxy) benzoic acid, and ester-forming derivatives thereof may be copolymerized.

The polycondensation catalyst in the present invention is not particularly limited, and any compound having activity as a polycondensation catalyst such as an antimony compound which has been most widely used in the past, a germanium compound, a titanium compound and an aluminum compound can be used. Although a titanium compound or an aluminum compound can be used, it is particularly preferable to use a titanium compound or an aluminum compound because it is relatively inexpensive and stains on the die during molding can be reduced at the same time.

The titanium compound is not particularly limited, but for example, titanium alkoxide, titanium complex, complex oxides whose main metal elements are titanium and silicon, and the like can be used.

Specific examples of the titanium alkoxide include:
Titanium methylate, titanium ethylate, titanium-n-propylate, titanium isopropylate, titanium tetra-
n-butyrate, titanium tetra-sec-butyrate,
Examples thereof include titanium tetra-tert-butyrate and titanium tetraethylene glycolate.

The titanium complex in the present invention is a titanium compound containing a chelating agent capable of coordinating to a titanium atom and is not particularly limited. Specifically, for example, an alkoxytitanium compound or the like is used as a base material and various chelating agents are added thereto, that is, hydroxycarboxylic acids such as lactic acid, glycolic acid and tartaric acid, hydroxypolycarboxylic acids such as citric acid and malic acid, and phthalates. Acid, trimellitic acid,
Trimesic acid, hemimellitic acid, polycarboxylic acids such as pyromellitic acid, glycine, bishydroxyethylglycine, hydroxyethylglycine, nitrilotripropionic acid, carboxyiminodiacetic acid, carboxymethyliminodipropionic acid, diethylenetriaminopentaacetic acid, Triethylenetetraminohexaacetic acid, iminodiacetic acid, iminodipropionic acid, hydroxyethyliminodiacetic acid, hydroxyethyliminodipropionic acid, methoxyethyliminodiacetic acid, alanine-N-acetic acid, alanine-N, N-diacetic acid, β -Alanine-N-acetic acid, β-alanine-N, N-
Diacetic acid, serine-N-acetic acid, serine-N, N-diacetic acid,
Isoserine-N, N-diacetic acid, aspartic acid-N-acetic acid, aspartic acid-N, N-diacetic acid, glutamic acid-
Aminocarboxylic acids such as N-acetic acid, glutamic acid-N, N-diacetic acid, aspartic acid, glutamic acid, leucine,
Coordinate nitrogen-containing compounds such as isoleucine and triethanolamine, nitrogen-containing polyvalent carboxylic acids such as ethylenediaminetetraacetic acid, hydroxyethyliminodiacetic acid, diethylenetriaminepentaacetic acid and triethylenetetramine-6acetic acid, acetylacetonate and acetoacetate. You can list things. Above all, it is preferable to use a titanium chelate compound of a polyvalent carboxylic acid because the resulting polymer has a good color tone and less foreign matter is generated. Particularly, titanium chelate of hydroxy polycarboxylic acid or nitrogen-containing polycarboxylic acid is preferable.

The composite oxide whose main metal element is titanium and silicon includes two kinds of elements, titanium and silicon, with respect to oxygen atoms, and these three kinds of elements including oxygen form one compound. I mean what I have. Therefore, a mixture of two or more kinds of oxides composed of a single element and oxygen, such as titanium oxide and silicon oxide, does not correspond to the composite oxide of the present invention.

When the main metal is a composite oxide consisting of titanium and silicon, the ratio of Ti and Si is not particularly limited, but the molar ratio of both metals (Ti / Si) is 20/80.
When the amount is above, the activity as a polymerization catalyst is high, and a small amount of polymerization is possible, which is preferable. More preferably Ti / S
i = 98/2 to 50/50.

The composite oxide whose main metal element is titanium and silicon is not particularly limited. For example, a coprecipitation method, a partial hydrolysis method or a coordination chemical sol prepared from an alkoxide compound having each metal element as a raw material. It can be synthesized by a gel method or the like. Here, the coprecipitation method is a method in which a solution having a predetermined composition containing two or more components is prepared, and a hydrolysis reaction is allowed to proceed with the composition to obtain a target composite oxide. Further, the partial hydrolysis method is a method in which one of the components is preliminarily hydrolyzed and the other component is added thereto to further promote the hydrolysis. On the other hand, the coordination chemistry sol-gel method is a method in which the organic polydentate ligand having a plurality of functional groups in the molecule coexists with a raw material such as a metal alkoxide, and a complex is formed between the two to allow the subsequent hydrolysis. It is intended to obtain a composite oxide by controlling the rate of decomposition reaction. The method for synthesizing the composite oxide as described above is
For example, it is described in Ueno et al., “Catalyst Preparation Using Metal Alkoxide”, IPC (1993) and the like.

Examples of the titanium compound used for producing the above-mentioned composite oxide include titanium isopropylate, titanium ethylate, titanium-tert-butyrate and the like. Examples of the silicon compound include methyl orthosilicate, ethyl orthosilicate and the like. Examples of the organic polydentate ligand used in the case of the coordination chemical sol-gel method include ethylene glycol, 1,2-propanediol, 1,2-butanediol, 1,3-propanediol, 1, Examples include 3-butanediol and 2,4-pentadiol. In addition, examples of the solvent for carrying out the reaction include methanol, ethanol, propanol, isopropanol and the like.

Other titanium compounds that can be used as the polycondensation catalyst in the present invention include titanium oxalate, titanium oxyoxalate, titanium tetrachloride, titanium tetrabromide, and inorganic titanium compounds such as hydrolyzates thereof. May be.

Among the titanium compounds used as the polycondensation catalyst in the present invention, the titanium complex is particularly preferably used because it produces little foreign matter.

The titanium compound used as the polycondensation catalyst in the present invention is preferably added to the polyester obtained in an amount of 0.1 to 100 ppm in terms of titanium atom because the polymerization activity is high and the color tone and heat resistance of the obtained polymer are good. The amount is more preferably 1 to 100 ppm, still more preferably 3 to 50 ppm.

The titanium compound used as the polycondensation catalyst in the present invention has a catalytic activity not only for the polycondensation reaction but also for the esterification reaction and the transesterification reaction. A polycondensation reaction may be subsequently performed. At this time, if necessary, a titanium compound may be additionally added before the start of the polycondensation reaction.

The aluminum compound in the present invention is not particularly limited. Specifically, aluminum hydroxide, aluminum chloride, inorganic aluminum compounds such as aluminum hydroxide chloride, aluminum acetate, aluminum benzoate, aluminum lactate, aluminum laurate,
Carboxylates such as aluminum stearate, aluminum ethylate, aluminum isopropylate, aluminum tri-n-butyrate, aluminum tri-s
ec-butyrate, aluminum tri-tert-butyrate, mono-sec-butoxyaluminum diisopropylate, which is a compound having a structure in which hydrogen of the hydroxyl group of the alcohol is replaced by aluminum element, aluminum alcoholate, ethyl acetoacetate aluminum diisopropylate, Aluminum tris (ethyl acetoacetate), alkyl acetoacetate aluminum diisopropylate, aluminum monoacetyl acetate bis (ethyl acetoacetate), aluminum tris (acetyl acetate), aluminum monoisopropoxy monooleoxyethyl acetoacetate, aluminum acetylacetonate, etc. Alkyl acetoacetate or acetic acid ester Aluminum chelate is a compound substituted with a chelating agent such as Chiruaseton like.

Among them, aluminum hydroxide, aluminum chloride, aluminum hydroxide chloride and aluminum acetate, which are relatively inexpensive, have a low molecular weight and a high content ratio of aluminum atoms, are preferably used.

Furthermore, the use of aluminum hydroxide or aluminum acetate is particularly preferable because it does not contain halogen, and the heat resistance and color tone of the obtained polymer are better. The aluminum acetate of the present invention may be so-called basic aluminum acetate which is generally commercially available.

The aluminum compound as the polycondensation catalyst in the present invention is preferably added to the obtained polyester in an amount of 1 to 500 ppm in terms of aluminum atom, because the polymerization activity is high and the color tone and heat resistance of the obtained polymer are good. It is more preferably 10 to 400 ppm, still more preferably 20 to 300 ppm.

In the present invention, at least one compound (B) selected from the group consisting of polyoxyalkylene glycol and its derivatives, cyclodextrin and its derivatives, calixarene and its derivatives, together with the compound (A) used as a polycondensation catalyst. ) To compound (A)
It is necessary to add the compound (B) and the compound (B) to the reaction system so that the mixing ratio (A / B) on the molar basis is 0.005 to 50.

If the mixing ratio (A / B) is less than 0.005, polycondensation activity may be insufficient, or mechanical properties such as strength of a molded product using the obtained polymer may be deteriorated. If it exceeds 50, the thermal stability of the polymer may be insufficient. More preferably, the mixing ratio (A /
B)) is from 0.05 to 10, particularly preferably from 0.1 to 5.

Specific examples of the polyoxyalkylene glycol and its derivatives in the present invention include polyethylene glycol, polypropylene glycol, polyoxytetramethylene glycol, and compounds obtained by blocking the ends of these compounds with benzoic acid or the like. . Among them, polyethylene glycol is preferable because the polymer has particularly good thermal stability.

The cyclodextrin and its derivative in the present invention are not particularly limited, but specifically,
α-cyclodextrin, β-cyclodextrin, γ
-Cyclodextrin etc. are mentioned.

The calixarene and its derivative in the present invention are not particularly limited, but specifically,
Calix (4) allene, calix (6) allene, calix (8) allene, calix [6] arene-p
-Hexasodium sulfonate n-hydrate, calix [8]
Arene-p-sulfonic acid octasodium n-hydrate, thiacalix (4) arene, thiacalix (6) arene, sulfonylcalix (4) arene and the like.

Among these compounds (B), polyoxyalkylene glycol and its derivatives which are relatively inexpensive and have a large effect of improving the thermal stability of the polymer are particularly preferable. The molecular weight is 400 to 20 in terms of weight average molecular weight.
It is preferable for it to be in the range of 0000 because the effect of improving heat resistance is large. More preferably, it is 600 to 50,000, and particularly preferably 600 to 20,000.

In the present invention, the compound (B) can be added at any stage of polyester polymerization, but the esterification reaction or transesterification reaction is substantially completed,
It is preferable to add it in the subsequent polycondensation reaction step before the pressure of the reaction system is reduced, because the compound (B) is easily added and the color tone of the polymer becomes good.

Further, it is preferable that the compound (A) and the compound (B) which are polycondensation catalysts are mixed in advance and then added to the reaction system because the thermal stability of the polymer becomes particularly good. Furthermore, the method of mixing both in water and / or diol and adding the obtained solution or slurry of the compound (A) and the compound (B) to the reaction system is excellent in operability and has thermal stability of the polymer. It is particularly preferable because the effect of improving the property is large.

In the present invention, the phosphorus compound may be added at any time before the completion of the polycondensation reaction for the purpose of improving the color tone of the polymer and improving the heat resistance of the obtained polymer. Examples of the phosphorus compound include phosphoric acid, phosphorous acid, phosphonic acid, phosphinic acid and esters thereof, but are not particularly limited.

When the polycondensation catalyst is a titanium compound, the addition of the phosphorus compound may deactivate the titanium compound.
It is preferable to add it so as to be less than or equal to ppm. It is more preferably 10 ppm or less. Further, it is preferable to stagger the addition timing of the phosphorus compound and the polycondensation catalyst because the delay of the polycondensation time is reduced.

In the present invention, in order to improve the process passability at the time of molding the obtained polyester into a fiber or a film, or to improve the color tone, inorganic particles or inorganic particles may be added at any time until the polycondensation reaction is completed. The polymer particles may be added in an amount of 0.01 to 10 wt% with respect to polyester. Of these, titanium oxide particles that are inexpensive and have excellent dispersibility in a polymer are preferably used.

Here, the content of titanium oxide particles is 0.05.
It is preferable that the content is ˜7 wt% because the process passability during molding is particularly good, and more preferably 0.1 to 3 wt%.
%. The average particle size is preferably 0.1 to 3 μm. The titanium oxide particles referred to here are
Particles that are generally used for improving the processability in the yarn making process or the film forming process and adjusting the color tone of the product, and do not substantially have the function of the polyester polymerization catalyst. Is.

The production method of the present invention will be described by taking polyethylene terephthalate as an example. The high molecular weight polyethylene terephthalate used for fibers, films and the like is usually produced by any of the following processes. That is, (1) a process in which terephthalic acid and ethylene glycol are used as raw materials, a low molecular weight polyethylene terephthalate or oligomer is obtained by a direct esterification reaction, and then a high molecular weight polymer is obtained by a polycondensation reaction, (2) dimethyl terephthalate and ethylene This is a process in which a low molecular weight substance is obtained by a transesterification reaction using glycol as a raw material, and then a high molecular weight polymer is obtained by a polycondensation reaction thereafter. Here, the esterification proceeds even without a catalyst, but in the transesterification reaction, it is usually allowed to proceed using a compound such as manganese, calcium, magnesium, zinc, lithium or titanium as a catalyst, and the transesterification reaction is substantially carried out. After the reaction is completed, a phosphorus compound may be added for the purpose of inactivating the catalyst used in the reaction.

The production method of the present invention comprises (1) or (2)
To the low polymer obtained in any stage of the series of reactions, preferably in the first half of the series of reactions (1) or (2), and a compound (A) and a compound (B) as polycondensation catalysts;
If necessary, particles of titanium oxide or the like, a phosphorus compound, a cobalt compound or the like are added and polycondensed to obtain a high molecular weight polyethylene glycol.

The above reaction is carried out in a batch system, a semi-batch system, a continuous system or the like, but the production method of the present invention can be applied to any of these systems.

[0042]

The present invention will be described in more detail with reference to the following examples. The physical property values in the examples were measured by the methods described below. (1) Intrinsic viscosity of polymer [η] It was measured at 25 ° C using orthochlorophenol as a solvent. (2) Color tone of polymer Hunter value (L, a, b) was measured using a color difference meter (SM color computer model SM-3) manufactured by Suga Test Instruments Co., Ltd.
Value). (3) Content of Titanium, Aluminum, and Phosphorus Elements in Polymer Fluorescent X-ray (Fluorescent X-ray analyzer 3270 manufactured by Rigaku Corporation)
Type) or ICP (inductively coupled plasma) emission analysis (Seiko Instruments SPS4000 type). If necessary, the following pretreatment was performed to remove the influence of particles such as titanium dioxide particles in the target polyester, and then fluorescent X-ray or ICP emission analysis was performed. That is, polyester is dissolved in orthochlorophenol, and the viscosity of the polymer solution is adjusted with chloroform as necessary, and then the particles are settled by a centrifuge. Then, only the supernatant liquid is collected by the gradient method, and the polymer is reprecipitated by adding acetone, filtered, and washed to obtain a polymer from which particles have been removed. Metal analysis was performed on the polymer obtained by removing the particles obtained by the above pretreatment. (4) Carboxyl end group amount of polyester (COO
H) Method of Maurice et al. [Anal. Chim. Act
a, 22, p363 (1960)]. (5) Thermostable polymer pellets are dried in advance at 150 ° C. under a reduced pressure of 133 Pa or less for 10 hours, and then an appropriate amount is charged into a test tube. After purging the inside of the test tube with nitrogen, the temperature is 300 ° C in advance.
Immerse and hold in a silicone oil bath whose temperature has been raised to. At the time when the entire contents were dissolved and after 8 hours, the polymer was sampled and the intrinsic viscosity [IV] of each polymer was sampled.
When 0 and [IV] 1 were set, the value represented by the following equation 1 was used as an index of thermal stability.

(Thermal stability index) = {[IV] 0− [IV] 1} / [IV] 0 (Equation 1) A thermal stability index of less than 0.55 is grade 1, 0.55 or more 0 Less than .60 is grade 2, less than 0.60 is less than 0.65 is 3
A grade of 0.65 or more was classified as a grade 4. The 1st to 3rd grade polymers can be preferably used, for example, because the degree of polymerization is less likely to decrease during molding.

Example 1 Ethylene glycol (manufactured by Kanto Chemical Co., Inc.) was mixed with titanium tetra-n-butyrate (manufactured by Kanto Chemical Co., Ltd.) and polyethylene glycol having a weight average molecular weight of 1000 (manufactured by Sanyo Kasei Co., Ltd.). It was added so that the molar ratio (A / B) was 3, and stirred at 120 ° C. for 1 hour to obtain a uniform solution (X). At this time, titanium tetra- in ethylene glycol
The concentration of n-butyrate was 5 wt% in terms of titanium atom.

A catalyst-free oligomer produced from high-purity terephthalic acid and ethylene glycol according to a conventional method is melted and stirred at 250 ° C., and the above-prepared solution (X) is obtained from the polyester obtained. It was added so as to be 15 ppm in terms of titanium atom. Then, while stirring the low polymer at 30 rpm, the reaction system was gradually heated from 250 ° C to 290 ° C and the pressure was adjusted to 40P.
lowered to a. The time required to reach the final temperature and the final pressure was both 60 minutes. When the stirring torque reached a predetermined value, the reaction system was purged with nitrogen and returned to normal pressure to stop the polycondensation reaction, discharged into cold water in a strand form and immediately cut to obtain polyester pellets. The time from the start of depressurization until the predetermined stirring torque was reached was 3 hours.

The polymer obtained has an intrinsic viscosity of 0.65,
The carboxyl terminal group concentration was 16 equivalents / ton, the thermal stability index was primary, and the polymer color tone was L = 55, b = 1.5, and the thermal stability was good and a polymer having an excellent color tone was obtained.

Examples 2 to 7, Comparative Examples 1 to 3 Except that the addition amount and type of the compound (A) which is a polycondensation catalyst and the type and amount of the compound (B) used in combination are changed as shown in Table 1. Was polymerized in the same manner as in Example 1. The results are shown in Table 1.

In Example 7, the compound (A) and the compound (B) were separately added to the reaction system.

In Comparative Example 1, the color tone of the obtained polymer was extremely poor, and at the same time, most of the polymers had insufficient thermal stability.

[0050]

[Table 1]

[0051]

[Table 2]

[0052]

According to the method for producing a polyester of the present invention, a polymer having excellent thermal stability and at the same time having a good color tone can be obtained.

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Claims (10)

[Claims] 1. A method for producing a polyester by polycondensing a product obtained by an esterification reaction or an ester exchange reaction between an aromatic dicarboxylic acid or an ester-forming derivative thereof and a diol or an ester-forming derivative thereof. For compound (A) used as a polycondensation catalyst, polyoxyalkylene glycol and its derivative,
At least one selected from the group consisting of cyclodextrin and its derivatives, calixarene and its derivatives
Of two compounds (B) are added to the reaction system such that the mixing ratio (A / B) of the compound (A) and the compound (B) on a molar basis is 0.005 to 50. Method. 2. The method for producing a polyester according to claim 1, wherein the compound (A) is premixed with the compound (B) and then added to the reaction system. 3. The method for producing a polyester according to claim 2, wherein the compound (A) and the compound (B) are mixed in water and / or a diol. 4. The method for producing a polyester according to claim 1, wherein the compound (A) is a titanium compound. 5. The method for producing a polyester according to claim 1, wherein the compound (A) is an aluminum compound. 6. The method for producing a polyester according to claim 1, wherein the compound (A) is a germanium compound. 7. The compound (B) has a weight average molecular weight of 400 to 2
It is polyoxyalkylene glycol of 00000 and its derivative, The manufacturing method of the polyester in any one of Claims 1-6 characterized by the above-mentioned. 8. The method for producing a polyester according to claim 7, wherein the compound (B) is polyethylene glycol. 9. Use in producing a polyester by polycondensing a product obtained by an esterification reaction or an ester exchange reaction between an aromatic dicarboxylic acid or its ester-forming derivative and a diol or its ester-forming derivative. As a catalyst, at least one compound (B) selected from the group consisting of polyoxyalkylene glycol and its derivatives, cyclodextrin and its derivatives, calixarene and its derivatives is added to the compound (A) used as a polycondensation catalyst. The mixing ratio (A / B) of the compound (A) and the compound (B) on a molar basis is 0.005.
A catalyst for producing a polyester, which is a mixture of the two so as to be about 50. 10. The catalyst for producing polyester according to claim 9, which is in the form of an aqueous solution or slurry of water and / or diol.