JP2002519458A - Polysulfone film - Google Patents

Abstract

  (57) [Summary] A film comprising a polysulfone, wherein the polysulfone contains up to about 1.4% by weight of a sulfone cyclic dimer.

Description

DETAILED DESCRIPTION OF THE INVENTION

FIELD OF THE INVENTION The present invention relates to novel films made from poly (aryl ether sulfone), wherein the poly (aryl ether sulfone) contains low levels of a sulfone cyclic dimer component. More specifically, the present invention relates to a poly (aryl ether sulfone) wherein the poly (aryl ether sulfone) contains a moiety from bisphenol A and the poly (aryl ether sulfone) contains up to 1.4% by weight of a sulfone cyclic dimer component. Aryl ether sulfone).

BACKGROUND OF THE INVENTION Over the years, numerous poly (aryl ether sulfones) have been known. These are linear polymers with many attractive features, such as excellent high temperature resistance, good electrical properties and stiffness. One such important commercial poly (aryl ether sulfone) is available from Amoco Polymers under the trademark UDEL.
, Inc. It is given by equation (1):

[0003]

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And has a T _{g of} about 190 ° C., and as described in US Pat. No. 4,108,837, the nucleophilic weight of disodium bisphenol A with 4,4′-dichlorodiphenylsulfone. Suitably prepared by condensation. A poly (aryl ether sulfone) containing a moiety derived from bisphenol A is hereinafter referred to as a polysulfone.

[0005] Due to their excellent mechanical and other properties, polysulfones can be used to make various films. However, a certain amount of sulfone cyclic dimer and cyclic oligomer material is also formed during the production of polysulfone, for example, as (1). The sulfone cyclic dimer has the structural formula (2):

[0006]

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[0007] In one important method used to prepare films from polysulfone polymers such as (1), a suitable low boiling solvent solution of the polymer is prepared and a predetermined amount of this solution is added to a shape or mold. And dried to remove the solvent, thereby leaving a film of the desired thickness. However, due to physical properties, the cyclic dimer (2) is typically much less soluble in the solvents used to make the film, and immediately after dissolving the polysulfone or shortly thereafter.
Some cyclic dimer precipitates, giving a cloudy mixture. Haze films from such solutions are poorly aesthetic, and if optical films are desired, haze makes the film unacceptable.

Accordingly, there is a need for a technique for obtaining films, particularly optical films, made from low levels of cyclic dimer polysulfone in polysulfone. The present invention provides such a film.

SUMMARY OF THE INVENTION The present invention is a film comprising a polysulfone, wherein the polysulfone contains up to about 1.4% by weight of a sulfone cyclic dimer. The invention is a film, preferably an optical film, wherein the film comprises polysulfone and the polysulfone used to make the film has a weight of about 1.4, based on the weight of polysulfone.
It is a film containing a sulfone cyclic dimer having a structural formula (2) of not more than% by weight. The films of the present invention have low levels of haze, especially low haze, due to the presence of the sulfone cyclic dimer.

The present invention also relates to a polysulfone comprising polysulfone, wherein the polysulfone used to make the film has less than about 1.4% by weight of a sulfone cyclic dimer, wherein the polysulfone immediately after its production, Is a film that has not been treated to remove the sulfone cyclic dimer by operations including dissolution of the sulfone cyclic dimer in a solvent, precipitation of the sulfone cyclic dimer, and separation of the precipitated cyclic dimer from the polysulfone.

DETAILED DESCRIPTION OF THE INVENTION The present invention is a film, preferably an optical film, made from a polysulfone thermoplastic resin, wherein the polysulfone is less than about 1.4% by weight, more preferably about 1.3% by weight. %, Most preferably up to about 1.2% by weight of the sulfone cyclic dimer.

[0012] Polysulfones useful for making the films of the present invention include repeating units:

[0013]

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Preferably, in at least about 50 mol%, more preferably at least 75 mol% of the repeating units, the divalent Ar ¹ group has the formula (3):

[0015]

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(Ie, derived from bisphenol A or the like). When other repeating units are present, divalent Ar ¹ is preferably p-phenylene, 4,4′-
At least one member selected from diphenylsulfone and other moieties from biphenyl. Polysulfones are available under the trademark Udel under the trademark Amoco Po
Available from lymers Inc. Udel polysulfone is the preferred polysulfone for making the films of the present invention. By the term "bisphenol A moiety" or "bisphenol A derived moiety" we mean a moiety or residue derived from bisphenol A and those having the above structural formula (3).

As used herein, the term “film” generally refers to a sheet-like material, typically, but not necessarily, transparent, but not necessarily transparent, flat or flat, preferably The thickness of the film is from about 10 μm to about 400 μm, more preferably from about 10 μm to about 200 μm (μm means micrometer). The films can be used for a variety of applications, including packaging, electronic components (eg, insulating layers), protective layers, covers, and the like. As used herein, the term optical film refers to a film used to transmit light, e.g., having a retardation of 100 nm or less (retardation) that is useful as a protective film for polarizing sheets. Birefringent optical films are mentioned and are useful for anti-glare materials, and are typically used in various anti-glare devices, such as 1 / 4λ (13) used in visual display terminal filters (VDT).
Birefringent optical films such as those having a retardation of 0-150 nm; λ is the wavelength of incident light).

The “delay value” R is the product of the birefringence of the film and the thickness of the film, as described above, and has the following formula:

[0019]

[Formula 1] R = d × | n ₁ −n ₂ | = Δn × d [where d represents the thickness of the film, and n ₁ represents the refractive index in the direction of the optical axis or in the direction perpendicular thereto. Where n ₂ represents the refractive index in the direction perpendicular to the direction of n ₁ , the refractive index being with respect to the sodium D line. ] Is represented by

The films of the present invention, and in particular, optical films, may be prepared by solution casting, melt extrusion,
Although it can be continuously produced from a polysulfone thermoplastic resin by calendering or the like, solution casting is preferred. Films produced by solvent casting are:
The resulting films are most preferred as they generally have good thickness uniformity and tend to have fewer defects such as gels or foreign particles.

Although solution casting is performed, it is important to maintain an appropriate concentration of polysulfone or polysulfone-containing polymer in the solution to be cast. Suitable concentrations of the polysulfone or polysulfone-containing polymer are usually from about 15 to about 35% by weight, based on the total weight of the solution.

The solvent used for the solution casting may be any solvent that dissolves the polysulfone, and is preferably sufficient to allow it to easily evaporate from the solution to form a film. It should be volatile. Suitable solvents include, for example,
Methylene chloride, chlorobenzene, 1,3-dioxolane and tetrahydrofuran.

The films produced may have defects such as die lines or undergo some stretching, depending on the film forming conditions. Such some stretching is effectively reduced by subjecting the film to a heat treatment. When the heat treatment of the film is performed at a temperature above the heat deflection temperature of the film, the birefringence of the film becomes essentially zero, resulting in an optical film that does not exhibit birefringence. This film is suitable for applications requiring zero birefringence, for example, a protective film for a polarizing sheet, a protective film for a laser card, and the like. Alternatively, the zero birefringent film can be subjected to uniaxial or biaxial stretching to produce the desired birefringence.

The uniaxial stretching of the film is performed by a known technique, for example, horizontal uniaxial stretching by tentering, longitudinal uniaxial stretching using a difference in peripheral speed of rolls, and compression stretching between rolls. In particular, transverse uniaxial stretching by tentering is preferable in order to reduce nonuniform optical coloring of the resulting film.

In order to achieve uniform stretching in transverse uniaxial stretching, it is important to appropriately select an appropriate stretching temperature. The stretching temperature must be higher than the temperature at which the yield point of the stress-strain curve in the tensile test apparently disappears. If it is within or below the temperature range at which the yield point appears in the stress-strain curve, stretching will cause non-uniform non-uniformity in film thickness, and the resulting stretched film will have a large It has a large fluctuation rate in fluctuation and delay.

Biaxial stretching involves first stretching uniaxially by any of the above techniques, followed by sequential stretching or transverse stretching, which includes performing a second stretch in a direction perpendicular to the first stretch. Simultaneous biaxial stretching including longitudinal stretching is performed at the same time. The biaxial stretching technique is appropriately selected according to the desired physical properties.

The stretching ratio is not particularly limited. It is usually from about 1.2 to about 6,0, preferably from about 1.2 to about 1.4, but will vary somewhat depending on the desired result.

Post-stretch heat treatment is useful for improving the two-dimensional stability and retardation uniformity of the resulting stretched film. The heat treatment temperature is preferably selected within a range from about the heat deflection temperature to the stretching temperature.

The retardation value (R) of an optical film can be appropriately selected depending on the end use. For example, for use as a color correction device in a super twisted nematic (STN) mode liquid crystal display, a suitable R value is from about 200 to about 1000 nm. For use as an optical film to compensate for liquid crystal cell color non-uniformity and improve image quality, suitable R values are from about zero to about 200
nm range. For use as an optical film having biaxial stretching to improve image angle characteristics and the like, a suitable R value is about 500 nm or less.
For use as a protective film for polarizing sheets, film stability is about 1
It has an R value of less than or equal to 00 nm and preferably has no stretching. Further, a suitable R value for use as an optical filter or the like is from about zero to about 120, depending on the purpose.
0 nm is selected.

Description and methods for making optical films are described in US Pat.
13, which patent is incorporated herein by reference.

[0031] Polysulfones can be produced by a method known in the art. For example, they can be produced by a method known as the carbonate method or the alkali metal hydroxide method.

In the carbonate method, the polysulfones can be prepared by adding substantially equimolar amounts of bisphenol A, optionally with one or more other bishydroxyaromatic compounds and dihalodiaryl sulfones, such as 4,4 ′ -Dichlorodiphenyl sulfone or 4,
In a solvent mixture comprising a solvent which forms an azeotrope with water with 4'-difluorodiphenyl sulfone and maintains the reaction medium in substantially anhydrous conditions during the polymerization, from about 0.5 to about 0.5 to about Produced by contact with about 1.0 mole of alkali metal carbonate. The temperature of the reaction mixture is from about 170C to about 250C, preferably from about 210C to about 235C, and is maintained for about 1 hour to about 15 hours.

In a particularly suitable modification for preparing a copolymer from bisphenol A and one or more additional dihydroxy compounds, a reactant other than the additional dihydroxy compound is charged and the reactants other than the additional dihydroxy compound are heated to about 120 ° C. to about 189 ° C. for about 1 hour. Heat to about 5 hours, add more dihydroxy compound, raise temperature, and bring mixture to about 200 ° C. to about 250 ° C.
Preferably, heating is performed at about 210 ° C. to about 240 ° C. for about 1 hour to 10 hours. The reaction is carried out in an inert atmosphere, for example in an atmosphere of nitrogen, at atmospheric pressure, although higher or lower temperatures may be used.

[0034] The polysulfone is then recovered by conventional techniques, for example, flocculation, solvent evaporation and the like.

The solvent mixture includes a solvent that forms an azeotrope with water and a polar aprotic solvent. Examples of the solvent that forms an azeotrope with water include aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, and chlorobenzene.

The polar aprotic solvents used are generally those known in the art for the preparation of polyarylethersulfones, for example, of the formula: R ₁ —S (O) _b —R ₁ where Each R ₁ represents a monovalent lower hydrocarbon group containing no aliphatic unsaturation, and preferably contains less than about 8 carbon atoms and when joined together represents a divalent alkylene group; Is an integer of 1 to 2. ], And sulfur-containing solvents such as those represented by Thus, in all of these solvents, all oxygen and two carbon atoms are attached to the sulfur atom. What is believed to be used to make poly (aryl ether sulfone) is
formula:

[0037]

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Wherein R ₂ is independently lower alkyl, for example, a group such as methyl, ethyl, propyl, butyl, etc .; aryl, for example, phenyl; and alkylphenyl, for example, tolyl, and The R ₂ group has, for example, the formula:

[0039]

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In divalent alkylene bridges such as are interconnected as in tetrahydrothiophene oxide and dioxide. ] It is a solvent like what has. In particular, these solvents include dimethyl sulfoxide, dimethyl sulfone, diphenyl sulfone, diethyl sulfoxide, diethyl sulfone, diisopropyl sulfone, tetrahydrothiophen-1,1-dioxide (commonly known as tetramethylene sulfone or sulfolane) and tetra. Thiophene-1-monoxide.

Further, a nitrogen-containing solvent can be used. These include dimethylacetamide, dimethylformamide and N-methyl-pyrrolidone.

The azeotrope-forming solvent and the polar aprotic solvent are typically about 1:10
It is used in a weight ratio of about 1: 1, preferably about 1: 5 to about 1: 3.

In the reaction, the hydroxy-containing compound, for example bisphenol A, is slowly converted in situ to its alkali salt by reacting it with an alkali metal carbonate. The alkali metal carbonate is preferably potassium carbonate. As indicated above, mixtures of carbonates such as potassium and sodium carbonate can also be used.

To maintain substantially anhydrous conditions during the polymerization, water is continuously removed from the reactants as an azeotrope with a solvent that forms an azeotrope.

It is important that the reaction medium be kept substantially anhydrous during the polycondensation. About 1%
Although the amount of water is acceptable, there are some advantages when using fluorinated dihalobenzenoid compounds, with substantially higher amounts of water desirably with halo compounds. Of the water, resulting in the formation of phenolic species and only low molecular weight products are obtained. Therefore, in order to ensure a higher polymer, the system needs to be substantially anhydrous, preferably
. It should contain less than 5% by weight of water.

Preferably, after the desired molecular weight is obtained, the polymer is treated with an activated aromatic or aliphatic halide, such as, for example, methyl chloride or benzyl chloride. Such treatment of the polymer converts the terminal hydroxyl groups to ether groups, thereby stabilizing the polymer. The polymer thus treated has good melt and oxidative stability.

Although the carbonation method for producing the polymers used in the present invention is simple and convenient, in some cases higher molecular weight products can be produced by the alkali metal hydroxide method. Johnson et al., US Pat. 4,108,83
7 and 4,175,175, the alkali metal hydroxide method described in
The double alkali metal salt of a dihydric phenol is contacted with a dihalobenzenoid compound under substantially anhydrous conditions in the presence of a sulfur-containing solvent as defined herein above.

In addition, polysulfone can be prepared by other methods known in the art, including bisphenol A and at least one dihydric phenol, including at least one dihalobenzenoid compound, for example, as described in US Pat. No. 4,176,22
Heat as described in 2 with a mixture of sodium carbonate or sodium bicarbonate and a second alkali metal carbonate or bicarbonate having a higher atomic number than that of sodium.

[0049] The molecular weight of the polysulfone utilized to make the films of the present invention is indicated by decreasing viscosity data in a suitable solvent such as methylene chloride, chloroform, N-methyl-pyrrolidone, and the like. The low viscosity of polysulfones is 25 ° C
Measured at a concentration of 0.2 g per 100 ml, suitably at least 0.3 dl
/ G, preferably at least 0.4 dl / g, typically about 1.5 d
not more than 1 / g.

The polysulfone may also contain additives such as heat stabilizers, ultraviolet light stabilizers, plasticizers and the like.

During the production of polysulfone, a certain amount of cyclic oligomeric material is formed as a by-product, including the methods described above. One such cyclic oligomer is a sulfone cyclic dimer (2). In a solution of polysulfone, most of the structural formulas (2)
Is present in a soluble form, but in small amounts, in an insoluble crystalline form. The amount present in crystalline form increases when the solution is kept for several days due to the continued crystallization of the cyclic dimer. Crystalline sulfone cyclic dimers cause undesirable levels of haze in films, especially optical films.

The films of the present invention, more preferably, optical films, are made of polysulfone having low levels of cyclic dimers. The polysulfones used to make the films of the present invention typically have about 1 to about 1 weight based on the weight of the polysulfone.
. It contains up to 4% by weight of the sulfone cyclic dimer, more preferably up to 1.3% by weight of the cyclic dimer, most preferably up to 1.2% by weight of the cyclic dimer. The films of the present invention, especially optical films, may have a thickness of from about 0.1 to about 1.
Advantageously, it comprises polysulfone having 0, more preferably about 0.1 to about 0.7% by weight of the sulfone cyclic dimer. The films of the present invention, especially optical films, have a low level of haze as measured by ASTM D-1003-35. Haze is preferably as measured on a film having a thickness of 2 mils,
Preferably about 3.0 or less, more preferably about 2.0 or less, most preferably about 1
. 3 or less.

A number of methods can be used to produce polysulfones with low cyclic dimers. In one method, the "solution method", a predetermined amount of polysulfone is dissolved in a suitable solvent and set aside to precipitate the cyclic dimer. After a sufficient time, the cyclic dimer is separated from the solution by filtration, sedimentation, centrifugation or any other method for separating solids from liquids. Prior to filtration or other separation, additional solvent is added to assist in the separation. The resulting liquid solution contains polysulfone with low levels of cyclic dimer. For example, the solvent can be removed by evaporation, distillation, or a combination thereof, producing a neat polymer with low levels of cyclic dimer. Suitable solvents for this process include, for example, methylene chloride, chlorobenzene, 1,
3-Dioxolane; or any other solvent capable of dissolving the polysulfone and precipitating the sulfone cyclic dimer. The concentration of polysulfone in the solvent may be from about 10 to about 50% by weight, more preferably from about 20 to about 30% by weight. The time for the solution to stand before settling properly could vary depending on the temperature, the concentration of the polymer and the solvent chosen. Generally, using the concentrations and solvents described above, 1-10 days is sufficient.

Another method for producing polysulfones containing low cyclic dimers is the agglomeration or anti-solvent method. In this method, the polysulfone is dissolved in a suitable solvent, for example, dimethyl sulfoxide, chlorobenzene, or a mixture thereof to form a solution of the polysulfone. This solution is mixed with an anti-solvent, ie, a solvent in which the polysulfone is insoluble, such as methanol, ethanol, isopropanol, water, a mixture of methanol and chlorobenzene, and the like. Preferably, the anti-solvent is chosen such that it is miscible with the dissolving solvent. When mixed with an anti-solvent, polysulfones containing low levels of cyclic dimer rapidly precipitate out of solution, ie, aggregate and can be removed from the mixture by filtration, centrifugation, sedimentation, and the like.

The concentration of the polysulfone in the solvent is about 1 to about 20% by weight, preferably about 2 to about 20% by weight.
About 10% by weight. The ratio of solvent to antisolvent is suitably from about 1: 2 to about 1: 5.
0, preferably about 1: 5 to about 1:30. Both the solution method and the aggregation method are methods for producing a low sulfone cyclic dimer polysulfone by removing the sulfone cyclic dimer from the polysulfone after the polysulfone is formed in the polymerization process.

Another method for producing polysulfones containing low levels of cyclic dimers is based on removing the sulfone cyclic dimers from the polysulfone after polymerization, for example, as described in the previous two operations. Absent. Rather, in this preferred method for making the polysulfones used to make the films of the present invention, polysulfones containing low levels of cyclic dimers are made directly. For example, polymerization reactions are used to produce polysulfones containing low levels of polysulfone cyclic dimers. As noted above, polysulfone is typically a dihalodiaryl sulfone, such as 4,4'-dichlorodiphenyl sulfone, with a dihydroxy aromatic compound including bisphenol A, under substantially anhydrous conditions, a base; And by reacting in the presence of a polar aprotic solvent and a solvent that forms an azeotrope with water. By appropriately adjusting the concentrations of bisphenol A (and other bisphenols, if used) and 4,4'-dihalodiaryl sulfone in the solvent mixture, polysulfones having substantially lower amounts of sulfone cyclic dimers Can be manufactured. Thus,
At the end of the polymerization reaction, the final polymerization solution (by-product salts, e.g., sodium chloride) is formed at the end of the polymerization reaction at the end of the polymerization reaction. Producing a polysulfone containing low levels of sulfone cyclic dimer when it appears to be at least 30% by weight, more preferably at least 40% by weight, most preferably at least about 50% by weight, based on the total weight) can do. For example, about 1
. Polysulfones having up to about 4% by weight of the sulfone cyclic dimer, more preferably up to about 1.3% by weight of the sulfone cyclic dimer, and most preferably up to about 1.2% by weight of the sulfone cyclic dimer can be produced by this method. . Films made from polysulfone in which the polysulfone has not been treated with a solvent to remove cyclic dimers are the preferred films of the present invention. Preferably, such films are prepared using a polymerization process as described above and adjusting the concentration of the reactants in the polymerization reaction solution mixture to provide a low level of sulfone cyclic dimer, based on the weight of polysulfone, e.g. It is made from polysulfone made only to give up to 0.4% by weight, more preferably up to about 1.3%, most preferably up to 1.2% by weight.

The following examples illustrate particular examples of the present invention, but do not limit the scope and generality of the invention in any way.

EXAMPLES The polysulfone used in the following examples is Udel P-1700,
Commercially available polysulfone supplied by oco Polymers, Inc. It has the following repeating units:

[0059]

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Is a polymer having It has a concentration of about 0.50
It has a low viscosity of g / dl and has a number average molecular weight of about 15,000 by gel permeation chromatography using tetrahydrofuran (THF) as solvent and using polystyrene molecular weight calibration standards. The polysulfone has a sulfone cyclic dimer level of 1.5% by weight. The amount of the sulfone cyclic dimer described herein in the polysulfone was measured using gel permeation chromatography (GPC). The GPC procedure was as follows: The polysulfone in tablet form, the precipitated powder sample or the polysulfone reaction solution was dissolved in methylene chloride to form an approximately 0.4% by weight polysulfone solution. The solution was analyzed on two 5 μm mixed-D size size exclusion chromatography columns from Polymer Laboratories. GPC analysis was performed using 10 μl of the polymer solution as the injection volume and methylene chloride as the mobile phase at a flow rate of 1.5 m.
Completed at 1 / min. Detection was achieved with UV light (254 nm). The last peak at the tail end of the polysulfone chromatogram was before that of any residual solvent such as dimethyl sulfoxide and chlorobenzene, which may be present, and was determined to be the sulfone cyclic dimer. The area of the sulfone cyclic dimer peak and the area of the entire polysulfone peak were measured, and the weight percent cyclic dimer was calculated from these areas. A standard polysulfone sample containing 1.5% by weight of cyclic dimer was used to calibrate the GPC operation.

Example 1 Table 1 shows the results of the "solution method" for reducing the level of sulfone cyclic dimer in polysulfone. In this example, a solution of polysulfone containing 1.50% by weight of cyclic dimer was prepared with the listed solvents and the listed concentrations by dissolving the polysulfone tablets using agitation to promote dissolution. did. After dissolution, the solutions were stored for the listed number of days until they became cloudy.

The cloudy solution was diluted with additional solvent to achieve a 10% by weight polymer solution in solvent. After such dilution, each solution was immediately filtered through a 5.0 micron PTFE membrane filter. Analysis of the filtered solid from an experiment using methylene chloride was found to be 85% by weight of the polysulfone cyclic dimer, ie, (2). The filtrate was analyzed for polysulfone cyclic dimer content and the results of the analysis are also shown in Table 1. These data indicate that solution methods can be used to produce polysulfones with low levels of sulfone cyclic dimers.

Example 2 Table 2 shows the results of the "aggregation method" for reducing the level of sulfone cyclic dimer in polysulfone. In this example, a solution of polysulfone containing 1.50% by weight sulfone cyclic dimer was prepared by dissolving the tablets of polysulfone using agitation to facilitate dissolution, and dissolving the listed solvents (DMSO
Dimethyl sulfoxide and MCB is chlorobenzene. ) And at the concentrations listed. After dissolution, the solution was slowly added to the listed non-solvents or anti-solvents. The addition was completed in the blender using rapid stirring. Addition to the non-solvent resulted in rapid precipitation or aggregation of the polysulfone, which was collected by filtration, weighed, and analyzed for sulfone cyclic dimer content. Polysulfone recovery was greater than 97%. Table 2 shows the amount of cyclic dimer present in the recovered polysulfone.

These data demonstrate that the aggregation method is useful for producing polysulfones with low sulfone cyclic dimer levels.

[0065]

[Table 1]

[0066]

[Table 2]

Example 3 51.36 g of a 500 ml 4-diameter round bottom flask equipped with a Dean-Stark trap filled with chlorobenzene with an overhead stirrer; a thermocouple; a nitrogen inlet; Bisphenol A (0.22
5 mol), 144 g of chlorobenzene (MCB) and 105 g of dimethylsulfoxide (DMSO) were charged and purged with nitrogen for 1/2 hour. 35.78 g
Of 50.11% sodium hydroxide was then added to the flask. Mix 90
After refluxing for minutes, water was removed from the trap with the return of chlorobenzene to the flask. After a 90 minute dehydration period, the MCB and water in the trap were drained and the MCB was continuously removed from the reactor and allowed to reach 165 ° C. 64.62 g at 165 ° C
Of dichlorodiphenylsulfone (0.225 mol) and 34.8 g of chlorobenzene was added dropwise over 2 minutes. The sulfone monomer solution was added and the evaporated MCB was removed from the reactor as quickly as possible. Low viscosity 0.50
The reaction was continued until dl / g (chloroform solvent, 0.2 g polymer in 100 ml at 25 ° C.) was reached. At this point, almost all of the MCB has been removed and the concentration of polysulfone in the remaining mixture is about 50%, based on the total weight of the mixture excluding salts.
% By weight. The mixture was diluted with 200 ml of chlorobenzene and cooled to 120 ° C. At 120 ° C., methyl chloride was bubbled through the reaction solution for 30 minutes. After 30 minutes, 1.04 g of 25% NaOH was added and the addition of methyl chloride was continued for another 30 minutes. The reaction was further diluted with about 100 ml of MCB, the heat source was removed, and the reaction was cooled to about 90 ° C. At 90 ° C., 10.0 ml of a DMSO solution of oxalic acid (0.07 g oxalic acid dihydrate / 1 ml DMSO) was added and the reaction was mixed for 5 minutes.

The polymer solution was pressure filtered through a 1.5 micron (indicated) glass fiber filter membrane. The polymer was recovered by slowly adding the solution to a solution of methanol and water (70/30 / w / w), which was rapidly stirred in the blender. The ratio of polymer solution to methanol / water solution was 1:10 w / w. The polymer was recovered by filtration, and the inside of the blender was thoroughly washed with fresh methanol / water solution of the same ratio. The wet polymer was dried in a vacuum oven at 150 ° C. for 20 hours. The low viscosity measured in chloroform (0.2 g polymer in 100 ml at 25 ° C.) was greater than 0.50 dl / g. The sulfone cyclic dimer is the same as the GP described above.
It was determined by method C to be 1.15% by weight.

Example 4 Polysulfone tablets (60 g) were added to methylene chloride (140 g) at room temperature. The resulting slurry was stirred overnight with an overhead mechanical stirrer to produce a 30% by weight solution. The resulting solution was poured into a doctor blade (8 mil thickness), placed on a level glass plate, and a gentle stretching of the doctor blade resulted in an 8 mil thick strip of polymer solution. The solvent was allowed to evaporate at room temperature in a fume hood by discarding the strip containing the wet solvent without any hindrance. After drying for 3 hours at 50 ° C. in an oven to condition the film, the thickness was measured by a micrometer to be about 2 mils. Multiple film samples were prepared from polysulfone samples containing 1.5 wt% and 1.1 wt% sulfone cyclic dimer levels.

A 2.5 ″ × 4 ″ measured film strip was cut from the film produced by the method described above. Slides were made from these filmstrips by gluing rigid paper to all four corners of the film. The obtained slide was used as a sample for haze measurement.

Haze was measured with a haze meter according to the ASTM D1003-35 test method. Table 3 shows the results.

[0072]

[Table 3]

The results in Table 3 show that films made from polysulfone resin containing 1.1% cyclic dimer have much less haze compared to films made from polysulfone containing 1.5% by weight cyclic dimer. Indicates that

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Claims (5)

[Claims] Claims 1. A polysulfone comprising about 1.4% by weight of a polysulfone.
A film containing the following sulfone cyclic dimer. 2. The film according to claim 1, which is an optical film. 3. The film of claim 1 produced by a polymerization process that produces polysulfone containing less than about 1.4% by weight of the sulfone cyclic dimer. 4. The film according to claim 1, which is produced by a solution casting method. 5. The film of claim 2, wherein the film has a degree of retardation of about 1 to about 1000 nm.