JP2020093526A - Method for cleaning platinum catalyst filter - Google Patents

Abstract

To provide a method for cleaning a platinum catalyst filter having a capability of regenerating a platinum catalyst filter in which oligomer degradability has been reduced due to adhesion of a compound in the platinum catalyst filter used for purification of the air circulating in a tenter device.SOLUTION: There is provided a method for cleaning a platinum catalyst filter, the platinum catalyst filter is cleaned by an alcohol solvent A having a boiling point of 250°C or higher and less than (X)°C, when the alcohol solvent having a boiling point of more than 250°C is the alcohol solvent A, and the boiling point of the alcohol solvent A is (X)°C. The alcohol solvent A preferably contains triethyleneglycol as a main component, and the platinum catalyst filter is preferably cleaned after calcined at a temperature of 300°C or higher and 600°C or lower.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to a method for cleaning a platinum catalyst filter having a reduced resolution due to the attachment of a compound.

Platinum catalyst is a catalyst mainly composed of platinum group elements, and since it is active in reactions such as hydrogenation, dehydrogenation, and oxidation, it is used for cleaning the air circulating in the tenter device for stretching and heat treatment of the film. It is used.

The tenter device is generally divided into a plurality of chambers from which the temperature can be individually controlled from the inlet to the outlet, and the sheet passes through the plurality of chambers having different temperatures until it becomes a film by stretching. In this process, oligomers are volatilized from the sheet or film, especially when passing through a room having a high temperature. Further, if the sheet conveyed to the entrance is coated with a coating material containing a silicone compound or the like in order to improve heat resistance and water resistance, silicone, silicone thermal decomposition product, silanes, and siloxane In addition to organosilicon compounds such as benzene, benzene, toluene, methyl ethyl ketone, ethyl acetate, etc. used as a solvent for the coating agent may be released into the air. In addition, although the generation mechanism is unknown, sulfur compounds, phosphorus compounds, etc. may be released into the air.

The oligomer contained in the air circulating in the tenter device is precipitated when its concentration reaches saturation or when a gas containing a large amount of oligomer flows into a room with a low temperature due to running of a sheet or film. , Contamination in the tenter device or foreign matter adhered to the film. In order to solve this problem, a method of arranging a heated platinum catalyst in the gas circulation path of the tenter device to decompose the oligomer has been proposed (Patent Document 1), but in the air circulating in the tenter device. However, there is a problem in that the oligomer decomposing ability of the platinum catalyst cannot be maintained for a long period of time because the compound contained in the above and its decomposition products adhere to the surface. Also, when a platinum catalyst is included in the filter (hereinafter, such a filter may be referred to as a platinum catalyst filter), similarly, the platinum catalyst may be removed by adhesion of a compound contained in the air or its decomposition product. The oligomer resolution is lowered and compounds such as oligomers are deposited on the surface. As a result, the platinum catalyst filter loses both the platinum catalyst function and the filter function.

When the platinum catalyst filter is in such a state, it is required to replace it with a new one or to regenerate it by washing or the like. Triethylene glycol heated to a high temperature, an alkaline aqueous solution, ultrasonic waves, etc. are used for cleaning the filter used in the film manufacturing process (Patent Document 2).

JP, 11-342535, A JP, 2015-112564, A

However, although Patent Document 1 provides a method of arranging a platinum catalyst to decompose an oligomer, there is no disclosure or suggestion of a method of regenerating the same. Further, although the method described in Patent Document 2 is effective for cleaning a filtration filter for removing foreign matters from a molten thermoplastic resin composition, whether or not the method can be used for a platinum catalyst filter and the method. It is unclear about the oligomer decomposability of the platinum catalyst filter after washing with.

An object of the present invention is to provide a method for cleaning a platinum catalyst filter, which solves the above-mentioned problems and can regenerate a platinum catalyst filter whose oligomer degradability is deteriorated by the attachment of a compound.

In order to solve the above problems, the present invention has the following configurations.
(1) When the alcohol solvent having a boiling point higher than 250° C. is alcohol solvent A and the boiling point of the alcohol solvent A is X° C., the platinum catalyst filter is washed with the alcohol solvent A having a temperature of 250° C. or higher and lower than X° C. A method for cleaning a platinum catalyst filter.
(2) The method for cleaning a platinum catalyst filter according to (1), wherein the alcohol solvent A contains triethylene glycol as a main component.
(3) The method for cleaning a platinum catalyst filter according to (1) or (2), characterized in that the platinum catalyst filter is roasted at a temperature of 300° C. or higher and 600° C. or lower and then washed.
(4) the basis weight of the platinum catalyst in the platinum catalyst filter is characterized by a 0.3 g / cm ³ or more ^{2.0g / cm 3, (1)} ~ according to any one of (3) platinum catalyst How to clean the filter.
(5) The method for cleaning a platinum catalyst filter according to any one of (1) to (4), wherein the platinum catalyst filter has a thickness of 5 mm or more and 30 mm or less.
(6) The method for cleaning a platinum catalyst filter according to any one of (1) to (5), characterized in that at least one of an organic substance and an inorganic substance is attached to the platinum catalyst filter.
(7) The method for cleaning a platinum catalyst filter according to (6), wherein an organic substance is attached to the platinum catalyst filter, and the organic substance is a component derived from polyethylene terephthalate.
(8) The platinum catalyst filter according to (7), wherein the polyethylene terephthalate-derived component contains at least one of terephthalic acid, monohydroxyethyl terephthalic acid, and bishydroxyethyl terephthalic acid as a constituent unit. Cleaning method.
(9) An inorganic substance is attached to the platinum catalyst filter, and the inorganic substance is at least one of a silicon oxide, a phosphorus oxide, and a sulfur oxide, (7) or (8) The method for cleaning a platinum catalyst filter according to 1.
(10) A stretching step of stretching a sheet in at least one direction using a tenter device having a platinum catalyst filter washed by the method for washing a platinum catalyst filter according to any one of (1) to (9) in an air circulation path. A method for producing a film, comprising:
(11) A tenter device comprising a platinum catalyst filter washed by the method for washing a platinum catalyst filter according to any one of (1) to (9) in an air circulation path.

It is an object of the present invention to provide a method for cleaning a platinum catalyst filter, which can regenerate a platinum catalyst filter whose oligomer degradability due to the attachment of a compound.

It is a schematic diagram showing a platinum catalyst filter attached to a frame. It is a schematic sectional drawing when the heat setting zone in the tenter device used in each Example and a comparative example is cut|disconnected by the film surface and the surface perpendicular|vertical to a longitudinal direction. It is the schematic showing the measuring device of the resolution of a platinum catalyst.

The method for cleaning a platinum catalyst filter of the present invention is a platinum catalyst with an alcohol solvent A having a boiling point of 250° C. or higher and an alcohol solvent A having a boiling point of 250° C. or higher and lower than X° C. when the boiling point of the alcohol solvent A is X° C. It is characterized in that the filter is washed. Hereinafter, the present invention will be specifically described.

The platinum catalyst filter refers to a filter containing at least one kind of platinum group element or a compound thereof, and the platinum group element is an element located in the 5th and 6th periods and the 8th to 10th groups in the periodic table, that is, ruthenium ( Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir), and platinum (Pt).

The boiling point is the temperature at which the saturated vapor pressure of a liquid becomes equal to the external pressure under 1 atm. The alcohol solvent means a solvent having a content of the alcohol component of 80% by mass or more and 100% by mass or less when all the constituent components are 100% by mass, and the alcohol solvent A is 100% by mass of the alcohol component in the alcohol solvent. When referred to as mass%, it means an alcohol solvent in which the boiling point of all alcohol components contained in 5 mass% or more exceeds 250°C. The boiling point of the alcohol solvent A refers to the minimum value of the boiling points of all the alcohol components contained in 5% by mass or more when the alcohol component in the alcohol solvent is 100% by mass.

In the method for cleaning the platinum catalyst filter of the present invention, it is important to clean the platinum catalyst filter with the alcohol solvent A at 250° C. or higher and lower than X° C. By adopting such an embodiment, it becomes possible to remove the compound or oligomer attached to the platinum catalyst while reducing the damage to the platinum catalyst due to heat, so that the function of the platinum catalyst filter is efficiently regenerated. be able to.

By setting the temperature of the alcohol solvent A at the time of cleaning to be less than X° C., evaporation and volatilization of the alcohol solvent A can be suppressed at the time of cleaning, so that a high cleaning effect can be realized. The lower limit of the boiling point of the alcohol solvent A is 250° C. from the lower limit of the temperature of the alcohol solvent A during washing. On the other hand, the upper limit of the boiling point of the alcohol solvent A is not particularly limited, but from the viewpoint of reducing deterioration of the platinum catalyst due to heat, it is preferably 500° C., more preferably 450° C., and 400° C. More preferable. That is, from the above viewpoint, the boiling point of the alcohol solvent A is preferably 250°C or higher and 500°C or lower, more preferably 250°C or higher and 450°C or lower, and further preferably 250°C or higher and 400°C or lower. Further, the temperature of the alcohol solvent A at the time of washing can be appropriately adjusted within a range of 250° C. or higher and lower than X° C. as long as the effect of the present invention is not impaired, but the organic matter derived from the adhered thermoplastic resin is decomposed. From the viewpoint of improving the cleaning effect by (X-10)° C. or more and less than X° C. (provided that X-10 is 250 or more).

The composition of the alcohol solvent A can be freely adjusted as long as the boiling point thereof is higher than 250° C. within a range that does not impair the effects of the present invention. However, from the viewpoint of cleaning efficiency and safety, it is preferable that the alcohol solvent A contains triethylene glycol as a main component. The phrase “alcohol solvent A contains triethylene glycol as a main component” means that alcohol solvent A contains more than 50 mass% of triethylene glycol when all the constituent components are 100 mass %.

The alcohol component constituting the alcohol solvent A is required to have features such as a high boiling point, a high affinity with water, a low skin absorbability, and no generation of toxic vapor. By using the alcohol component having such characteristics, it is possible to reduce the decrease in cleaning effect due to evaporation during heating, improve the ease of handling during cleaning, improve the safety of the cleaning operator, and reduce environmental pollution. it can.

Triethylene glycol is an alcohol with a boiling point of 287°C, has high affinity with water, is colorless and odorless, has low skin absorbability, and does not generate toxic vapor even when decomposed by heating or the like. Therefore, it is suitable as an alcohol component constituting the alcohol solvent A. From the above viewpoint, it is preferable that the alcohol solvent A contains 90 mass% or more and 100 mass% or less of triethylene glycol when all the constituent components are 100 mass %.

In addition, in the method for cleaning a platinum catalyst filter of the present invention, it is preferable that the platinum catalyst filter is roasted at a temperature of 300° C. or higher and 600° C. or lower and then washed. Some compounds and oligomers may not be sufficiently removed even by washing with the alcohol solvent A at 250° C. or higher and lower than X° C., and may remain as an adhered substance. By performing the above-mentioned roasting treatment before washing, the compound or oligomer attached to the surface of the platinum catalyst filter can be partially decomposed by burning or carbonizing, or by activating the platinum catalyst filter. Therefore, the compounds and oligomers attached to the platinum catalyst filter are more easily released, and the cleaning efficiency with the alcohol solvent A, which is subsequently performed, is improved. More specifically, by roasting the platinum catalyst filter at 300° C. or higher, combustion, carbonization, and decomposition of the deposit are sufficiently performed. On the other hand, by roasting the platinum catalyst filter at 600° C. or lower, thermal deterioration of the structure of the platinum catalyst filter can be suppressed and its functional loss can be reduced. From the above viewpoint, the temperature during roasting is more preferably 450°C or higher and 550°C or lower.

The roasting time of the platinum catalyst filter is not particularly limited as long as the function of the platinum catalyst filter is not impaired, but from the viewpoint of simultaneously improving the cleaning efficiency and maintaining the function of the platinum catalyst filter, it is preferably 60 minutes or more and 300 minutes or less. By roasting the platinum catalyst filter for 60 minutes or more, combustion, carbonization and decomposition of the adhered substances are sufficiently performed. On the other hand, when the roasting time of the platinum catalyst filter is 300 minutes or less, thermal deterioration of the structure of the platinum catalyst filter can be suppressed, and its functional loss can be reduced. From the above viewpoint, the roasting time of the platinum catalyst filter is more preferably 90 minutes or more and 270 minutes or less.

In the method for cleaning a platinum catalyst filter of the present invention, the basis weight of the platinum catalyst in the platinum catalyst filter can be appropriately adjusted within the range that does not impair the effects of the present invention. However, from the viewpoint of achieving both the function of the platinum catalyst and the function of the filter, the basis weight of the platinum catalyst in the platinum catalyst filter is preferably 0.3 g/cm ³ or more and 2.0 g/cm ³ or less. The weight per unit area of the platinum catalyst can be calculated from the volume and mass of the portion of the platinum catalyst filter containing the platinum catalyst when macroscopically observed.

When the weight of the platinum catalyst in the platinum catalyst filter (hereinafter sometimes simply referred to as the weight of the platinum catalyst) is 0.3 g/cm ³ or more, the mesh of the filter becomes appropriately dense, so that the platinum catalyst It becomes easy to exhibit sufficient oligomer resolution. On the other hand, when the basis weight of the platinum catalyst is set to 2.0 g/cm ³ or less, the mesh of the filter becomes moderately coarse, and therefore the deterioration of the function as a filter due to the pressure loss during use and the deterioration of the cleaning effect should be reduced. Will be easier. From the above viewpoint, the basis weight of the platinum catalyst is more preferably 0.4 g/cm ³ or more and 1.0 g/cm ³ or less, and further preferably 0.5 g/cm ³ or more and 0.8 g/cm ³ or less. preferable.

In addition, in the method for cleaning a platinum catalyst filter of the present invention, the thickness of the platinum catalyst filter can be appropriately adjusted within a range that does not impair the effects of the present invention. However, from the viewpoint of achieving both the function of the platinum catalyst and the function of the filter, the thickness of the platinum catalyst filter is preferably 5 mm or more and 30 mm or less. The thickness of the platinum catalyst filter means the thickness of the portion containing the platinum catalyst in the platinum catalyst filter, and the measurement can be performed with a caliper.

By setting the thickness of the platinum catalyst filter to 5 mm or more, the amount of platinum catalyst can be ensured to the extent that sufficient oligomer decomposing ability is exhibited, and by setting the thickness of the platinum catalyst filter to 30 mm or less, the thickness becomes excessive. It becomes easy to reduce the deterioration of the function as a filter and the deterioration of the cleaning effect due to the pressure loss during use. From the above viewpoint, the thickness of the platinum catalyst filter is more preferably 7 mm or more and 20 mm or less, and further preferably 8 mm or more and 15 mm or less.

Usually, a platinum catalyst has a low catalytic activity due to an organic substance or an inorganic substance being attached to a catalytically active site due to long-term use. The method for cleaning a platinum catalyst filter according to the present invention is capable of recovering the catalytic activity of the platinum catalyst filter in such a state by removing the attached organic substances and inorganic substances. That is, in the method for cleaning a platinum catalyst filter of the present invention, it is preferable that at least one of an organic substance and an inorganic substance is attached to the platinum catalyst filter.

The organic substance attached to the platinum catalyst filter (organic substance removed by washing) is not particularly limited as long as the effect of the present invention is not impaired, but polyethylene terephthalate is a thermoplastic resin preferably used for the film, and polyethylene. Considering the fact that terephthalate is easily sublimated by high temperature treatment, it is preferable that the organic substance is a component derived from polyethylene terephthalate, and contains at least one of terephthalic acid, monohydroxyethyl terephthalic acid, and bishydroxyethyl terephthalic acid as a constituent unit. More preferably, it is a component derived from polyethylene terephthalate.

In the manufacturing process of a polyethylene terephthalate film, polyethylene containing at least one of terephthalic acid (TPA), monohydroxyethyl terephthalic acid (MHET), and bishydroxyethyl terephthalic acid (BHET) as a constituent unit, particularly during heat treatment in a tenter device. In addition to terephthalate-derived oligomers (including monomers), these decomposition products and the like are generated and adhere to the platinum catalyst filter. Since such deposits dissolve in the alcohol solvent A, washing the platinum catalyst filter to which these deposits adhere with the alcohol solvent A makes it possible to remove these deposits.

"Containing at least one of terephthalic acid, monohydroxyethyl terephthalic acid, and bishydroxyethyl terephthalic acid as a constituent unit" means including these constituent units in the molecule (chain), and a compound that satisfies this requirement. Examples of the monomer include monomers composed of these constituent units and oligomers containing these constituent units. Since these components are dissolved in the alcohol solvent A, the function of the platinum catalyst filter to which these components adhere can be easily restored by the method for cleaning the platinum catalyst filter of the present invention. In addition, examples of decomposition products of the above-mentioned components derived from polyethylene terephthalate include acetaldehyde, formaldehyde, benzoic acid, acetic acid, and formic acid.

Furthermore, as the organic matter to be attached, other than the above, organic silicone compounds such as silicone, silicone thermal decomposition product, silanes and siloxanes can be mentioned. These organosilicon compounds are coated with a coating agent containing a silicon compound on the surface of the film in order to improve the heat resistance and water resistance when the thermoplastic resin composition forming the film contains a silicon compound as an additive. When it does, it often occurs. Such an organosilicon compound is highly harmful, and it needs to be decomposed with a platinum catalyst filter because it decomposes thermally at around 200°C to form a sticky substance such as tar. Then, these deposit and reduce the resolution of the platinum catalyst filter. Therefore, it is also preferable to remove these compounds by the method for cleaning the platinum catalyst filter of the present invention from the viewpoint of recovery of the function.

The inorganic substance attached to the platinum catalyst filter (inorganic substance removed by washing) is not particularly limited as long as the effect of the present invention is not impaired, but from the viewpoint of a substance that is a main factor that reduces the effect of the platinum catalyst, silicon It is preferably at least one of oxides, phosphorus oxides, and sulfur oxides. For some of these compounds, although the details of the generation mechanism are unknown, they are released into the air inside the tenter device from films, paints, and lubricating oils used in the tenter device, or were released. It is considered that the compound is generated by being oxidized in the air in the tenter device. When these compounds reach the platinum catalyst, they may selectively bond with the active metal to form a non-volatile oxide on the active metal, leading to a reduction in the performance of the platinum catalyst. Since such a compound has an effect even at an extremely low concentration (ppb order), it is preferable to remove it from the surface of the platinum catalyst filter by washing.

Hereinafter, the method for producing the film of the present invention will be described. The method for producing a film of the present invention comprises a stretching step of stretching a sheet in at least one direction by using a tenter device equipped with a platinum catalyst filter washed by the method for washing a platinum catalyst filter of the present invention in an air circulation path. Characterize. A tenter device is a sheet that grips both ends of the sheet in the width direction, while the clips are running in the transport direction, while adjusting the speed of the clips and widening the interval to move the sheet in at least one of the longitudinal direction and the width direction. An apparatus for stretching a film into a film, and an air circulation path means a path through which gas in a room can circulate. “Providing a platinum catalyst filter cleaned by the method for cleaning a platinum catalyst filter of the present invention in an air circulation path” means that at least one of the air circulation paths in a tenter device is platinum cleaned by the method for cleaning a platinum catalyst filter of the present invention. Refers to placing a catalyst filter.

The configuration of the tenter device is not particularly limited as long as the effects of the present invention are not impaired, but from the viewpoint of continuously performing stretching and subsequent heat setting, from the inlet side, a preheating zone, a drawing zone, a heat setting zone, and cooling. It is preferably provided with zones. The preheating zone refers to a section in which the sheet entering from the inlet is heated to the stretching temperature, and the stretching zone refers to a section in which the preheated sheet is stretched in at least one direction. The stretching direction and the magnification in the stretching zone can be adjusted by, for example, the spread of the clip in the width direction and the difference in traveling speed between the preceding clip and the following clip (hereinafter, also referred to as clip speed difference). it can. More specifically, stretching in the longitudinal direction is possible due to the speed difference of the clip, and stretching in the width direction is possible due to the widening of the clip in the width direction. Then, by increasing the speed difference of the clip and the spread of the clip in the width direction, the draw ratio in each direction can be increased.

The heat setting zone refers to a room in which a film obtained by stretching is treated at a temperature higher than the stretching temperature (hereinafter, this treatment is sometimes referred to as heat setting). improves. The cooling zone is a room for cooling the film heated in the heat setting zone. The number of rooms in the preheating zone, the stretching zone, the heat setting zone, and the cooling zone may be one or more than one as long as the effects of the present invention are not impaired. May have a mode in which the temperature can be controlled for each room.

By adopting such an embodiment, the decomposition of the oligomer or the like that sublimes from the film into the air in the tenter device is promoted, so that the occurrence of defects and the like due to these components can be suppressed. In addition, since platinum catalysts are generally expensive, the cost of manufacturing is high if they are replaced with new ones each time the resolution is degraded, but platinum catalyst filters washed by the platinum catalyst filter washing method are used instead of new ones. Thus, it is possible to reduce the increase in manufacturing cost.

Hereinafter, the film manufacturing apparatus of the present invention will be described. The apparatus for producing a film of the present invention is characterized in that a platinum catalyst filter washed by the method for washing a platinum catalyst filter of the present invention is provided in an air circulation path. By adopting such a mode, the tenter device can produce a high quality film at low cost as described above.

Hereinafter, the method for cleaning the platinum catalyst filter of the present invention will be specifically described by taking an example of using triethylene glycol as the alcohol solvent A, but the method for cleaning the platinum catalyst filter of the present invention is not limited to this embodiment. ..

First, triethylene glycol (boiling point: 287° C.) is attached to a platinum catalyst filter whose resolution has deteriorated due to long-term use. The adhesion of triethylene glycol to the platinum catalyst filter is performed, for example, by applying triethylene glycol to a portion of the platinum catalyst filter where the organic substance or the inorganic substance is attached, or by immersing the platinum catalyst filter in the triethylene glycol. be able to. Above all, it is preferable to immerse the platinum catalyst filter in triethylene glycol from the viewpoint of permeating triethylene glycol into the platinum catalyst filter to enhance the regeneration effect.

Next, the temperature of triethylene glycol is raised to 250° C. or higher and lower than 287° C., and the state is maintained for a certain period of time (preferably 5 to 20 hours), whereby the inorganic substances can be washed off from the surface, and the catalytic effect and triethylene glycol can be further removed. By reacting with glycol, organic substances attached to the platinum catalyst filter can be decomposed and removed. As a specific example of decomposition and removal of organic matter, when polyethylene terephthalate attached to a platinum catalyst filter is treated with triethylene glycol, bis-2-hydroxyethyl terephthalate is produced, which is finally converted to water by the catalytic effect of the platinum catalyst filter. It may be decomposed into carbon dioxide. Further, such an organic substance derived from a thermoplastic resin usually has a higher decomposition rate at higher temperatures, and therefore triethylene glycol is preferably heated to around the boiling point, specifically, 277°C or higher and lower than 287°C.

After that, it is preferable to wash the platinum catalyst filter with water in order to remove triethylene glycol and the like. This washing with water is preferably high pressure washing from the viewpoint of improving the washing effect. From the same viewpoint, a method of circulating water preheated to 50° C. to 90° C. and a method of giving ultrasonic vibration in a water tank filled with water preheated to 50° C. to 90° C. are also preferable. Can be used.

Hereinafter, the method for producing the film of the present invention will be specifically described by taking the production of a biaxially oriented film by a sequential biaxial stretching method as an example, but the method for cleaning the platinum catalyst filter of the present invention is not limited to this embodiment. ..

First, the thermoplastic resin pellets are supplied to the raw material charging section of the extruder and melted by heating. After that, the extrusion amount of the thermoplastic resin is made uniform by a gear pump or the like, the melted thermoplastic resin is extruded, and foreign matters and gelled substances are removed through a filter or the like. At this time, the number of extruders may be one or more. When using a plurality of extruders, the thermoplastic resin that has passed through the filter is fed to the laminating apparatus. A multi-manifold die, a feed block, a static mixer, or the like can be used as the laminating device, and these may be arbitrarily combined.

The thermoplastic resin melt thus obtained is discharged from the die as a sheet-like melt, and extruded onto a rotary cooling body such as a casting drum to be cooled and solidified to obtain a non-oriented sheet. As a specific method for obtaining a non-oriented sheet from a sheet-shaped melt, a wire-shaped, tape-shaped, needle-shaped, or knife-shaped electrode is used, and the sheet-shaped melt is rotated by an electrostatic force to a rotary cooling body such as a casting drum. It is preferable to bring it into close contact with and to solidify it by quenching. Other methods include blowing air in a slit shape, spot shape, or surface shape to bring the sheet-shaped melt into close contact with the rotary cooling body for rapid solidification, or with a nip roll to bring the sheet-like melt into close contact with the rotating cooling body. It is also preferable to use a method of rapidly cooling and solidifying.

Next, the obtained non-oriented sheet is stretched in the longitudinal direction (longitudinal stretching) to obtain a uniaxially oriented film. The longitudinal stretching can be performed using stretching rolls having different peripheral speeds, and can be performed in one stage or in multiple stages. The longitudinal stretching ratio can be appropriately selected depending on the intended use, the composition of raw materials, etc., but is preferably 2.0 to 7.0 times. In the longitudinal stretching, after heating the non-oriented sheet with a preheating roll, it is possible to further heat the non-oriented sheet with an infrared heater or the like.

After the longitudinal stretching, it is possible to provide a step of applying a coating agent for forming a functional layer such as an easy-adhesion layer on both sides or one side of the obtained uniaxially oriented film. The method for applying the coating agent is not particularly limited, but for example, a reverse coating method, a gravure coating method, a rod coating method, a bar coating method, a wire bar coating method, a die coating method, a spray coating method, or the like can be used.

Then, the uniaxially oriented film obtained by the longitudinal stretching is introduced into a tenter device and stretched in the width direction (transverse stretching) to obtain a biaxially oriented film. The tenter device used when performing the transverse stretching is provided with a gas circulation path having therein a platinum catalyst filter cleaned by the method for cleaning a platinum catalyst filter of the present invention and a heating mechanism. The temperature of the platinum catalyst filter is preferably controlled to 210°C or higher and lower than 400°C from the viewpoint of achieving both activity expression and durability of the catalyst. By adopting such an aspect, the catalyst effect of the platinum catalyst filter is exhibited, and the equipment is contaminated by the oligomers volatilized from the uniaxially oriented film or the biaxially oriented film in the tenter and the deposition of melamines volatilized from the coating agent. It is possible to reduce the occurrence of foreign matter and foreign matter and reduce the frequency of replacement of the platinum catalyst filter.

The tenter device grips the widthwise both ends of the uniaxially oriented film by the clip running inside the preheating zone, the stretching zone, the heat fixing zone, and the cooling zone in this order to bring the uniaxially oriented film to the stretching temperature. It is heated and transversely stretched, and then heat set and cooled. In this way, a biaxially oriented film can be obtained. Each zone in the tenter device may be configured by only one room or may be configured by a plurality of rooms in which the temperature setting can be changed for each zone.

The temperature of the preheating zone and the stretching zone depends on the thickness of the film to be finally obtained, the composition of the raw material, the stretching speed, the presence or absence of in-line coating, etc., but is preferably 80° C. or higher and 160° C. or lower, and 85° C. or higher and 130° C. The following is more preferable, and 90°C or more and 120°C or less is still more preferable. By setting the temperature of the preheating zone and the stretching zone to 80° C. or higher, the breakage of the film is reduced, and by setting the temperature to 160° C. or lower, a film having sufficient strength can be obtained.

The transverse stretching ratio depends on the thickness of the finally obtained film, the composition of raw materials, the stretching speed, the presence or absence of in-line coating, etc., but is 2.5 times or more from the viewpoint of preventing stretching unevenness or film breakage. It is preferably 0 times or less, more preferably 3.0 times or more and 5.5 times or less, still more preferably 3.5 times or more and 5.0 times or less.

The biaxially oriented film thus obtained is cooled in the subsequent conveying step, once wound as an intermediate roll by a wide width winder, and then cut into a required width and length by a slitter to obtain a final product. Become.

In the method for producing a film of the present invention, after the transverse stretching step, in order to reduce the occurrence of scratches and the like caused by the friction of the film surface when wound as an intermediate roll, knurling near the widthwise ends. It may be embossed. It should be noted that such an embossed portion can be cut and removed by a slitter in the process of forming the final product, like the edge portion having a large film thickness.

The film obtained by the method for producing a film of the present invention has few defects caused by oligomers and can be used as various optical films. Specifically, it can be preferably used as a base film for a prism sheet, a base film for a hard coat, a base film for an antireflection (AR) film, a base film for light diffusion, a transparent conductive film and the like.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples.

[Platinum catalyst filter]
A platinum catalyst filter having a size of 440 mm×590 mm and a thickness of 11 mm and having a basis weight of 0.6 g/cm ³ measured by the method described later in “(7) Weight of platinum catalyst filter” (product name: NM manufactured by JGC Universal Corporation) -12) was used (since there is no portion containing no platinum catalyst, the product thickness of 11 mm was regarded as the platinum catalyst filter thickness). The thickness of the platinum catalyst in each Example was adjusted by thinly cutting the platinum catalyst filter or by connecting a plurality of them, and the thickness was measured with a caliper. As shown in FIG. 1, the platinum catalyst filter 1 was attached by a fixture 2 to a frame 3 of a size suitable for the gas circulation path of the heat fixing chamber of the tenter device. In addition, each measurement described below and cleaning in each Example and Comparative Example were performed by cutting into a size of “10 mm×10 mm×thickness” (hereinafter, the cut platinum catalyst may be referred to as a platinum catalyst piece). The small pieces of platinum catalyst are simply obtained by reducing the area of the platinum catalyst filter, and the shape and function of the filter are maintained.

[Arrangement of tenter device and platinum catalyst]
The tenter device had a preheating zone, a stretching zone, a heat setting zone, and a cooling zone in this order, and the platinum catalyst attached to the frame was placed in the air circulation path of the heat setting zone. Hereinafter, the aspect of the tenter device will be specifically described with reference to FIG. FIG. 2 is a schematic cross-sectional view of the heat setting zone in the tenter device used in each of the examples and comparative examples, taken along a plane perpendicular to the film surface and the longitudinal direction. In the heat fixing zone 5 of the tenter device 4, hot air is blown out from the nozzles 7a and 7b which are arranged above and below the film 6 traveling inside thereof. The hot air blown out circulates in the air circulation path 9 by an air circulation fan 8 powered by a motor (indicated by M in FIG. 2), is temperature-controlled by the steam heater 10, and is again discharged from the nozzles 7a and 8b. Erupted. A platinum catalyst filter 12 attached to a frame is provided on the upstream side of a filter 11 in the air circulation path 9 (upstream of the steam heater 10 ), and the electric heater 13 faces the platinum catalyst filter 12 attached to the frame. It is arranged. With this electric heater 13, the platinum catalyst filter 12 attached to the frame can be heated to a desired temperature.

[Production of film]
The raw materials were adjusted and mixed at a ratio of 2.5% by mass of polyethylene terephthalate containing 97.5% by mass of polyethylene terephthalate and 1 to 2% by mass of silica particles in all components, and the mixture was dried at 180° C. for 3 hours, and then the temperature was raised. It was fed to an extruder controlled at 270 to 300°C. The obtained molten polyethylene terephthalate composition was extruded into a sheet form from a T die and cooled and solidified in a cooling drum having a surface temperature of 25° C. to obtain a non-oriented sheet. Further, the non-oriented sheet is guided to a roll group heated to 85 to 98° C., stretched at a magnification of 3.4 times in the longitudinal direction due to the peripheral speed difference, and then temporarily cooled by a roll group at a temperature of 21° C. to form a uniaxially oriented film. Got Then, the widthwise both ends of the uniaxially oriented film are guided to a tenter device while being gripped by a plurality of clips, and stretched at a magnification of 3.6 in the width direction in an atmosphere heated to 120° C. in the same tenter device. It was heat-set at 200° C., uniformly cooled slowly, and then cooled to room temperature to obtain a biaxially oriented film. The biaxially oriented film was produced in this step until the cumulative number of production days from the start of production reached 180 days. During this period, the platinum catalyst was arranged as described in [Arrangement of tenter device and platinum catalyst].

[Measurement and evaluation of each item]
The measurement and evaluation of each item were performed by the following methods. In addition, the amount of inorganic substances attached means the ratio (%) of the amount of inorganic substances remaining on the platinum catalyst pieces after washing to the amount of inorganic substances attached to the platinum catalyst pieces that were not washed after use. It refers to the ratio (%) of the amount of organic substances remaining on the platinum catalyst pieces after washing to the amount of organic substances attached to the platinum catalyst pieces that were not washed.

(1) Inorganic substance adhesion amount First, carbon deposition was performed on the surface of a platinum catalyst piece to obtain a measurement sample. Next, element distribution analysis of the surface of each measurement sample was performed using a wire probe microanalyzer (FE-EPMA:WDX), and the amount of inorganic substance was calculated by quantitative analysis from the obtained results. After that, the amount of inorganic substances adhering to the platinum catalyst pieces that were not washed after use was set to 100%, and the amount of inorganic substances adhering to each platinum catalyst piece after washing was calculated. The amount (%) was used. The measuring device and the measuring conditions used for the element distribution analysis are as follows.
Measuring device: JEOL model number "JXA-8530F"
Accelerating voltage: 20kV
Irradiation current: 50nA
Measurement time: 20 msec
Beam size: 1 μm
Area size: 82μm x 61μm
Analytical X-ray/spectroscopic crystal: Cr Kα, Ni Kα, Si Kα, Pt Kα, Al Kα, O Kα, C Kα.

(2) Organic substance adhesion amount First, a small piece of platinum catalyst was immersed in 5 mL of dimethylformamide, and subjected to ultrasonic treatment for 60 minutes. The obtained extract was collected in a 10-mL volumetric flask, and dimethylformamide was further added to adjust the volume to 10 mL to obtain a measurement solution. In parallel, 0.01 g each of terephthalic acid, monohydroxyethyl terephthalic acid, and bishydroxyethyl terephthalic acid were weighed and mixed, and a mixed solution of dimethylformamide and ethanol (dimethylformamide:ethanol=3:7 (mass ratio )) It was dissolved in 10 mL to prepare a standard stock solution (concentration of each compound: about 1,000 μg/mL). Furthermore, after diluting the standard stock solution with a mixed solution of dimethylformamide and ethanol at multiple ratios to prepare a plurality of standard solutions, LC/UV chromatographic analysis of each standard solution obtained was performed, and the obtained detection peak intensities were obtained. A calibration curve was prepared from the ratio and the concentration of each standard solution. Then, LC/UV chromatographic analysis of each measurement solution was performed, and the amount of organic substances in each measurement solution was determined from the obtained detection peak intensity ratio and the calibration curve. After that, the amount of organic substance in the measurement solution prepared from each platinum catalyst piece after washing is calculated by setting the amount of the organic substance in the measurement solution prepared from the platinum catalyst piece not washed after use as 100%, and the obtained value is washed. The amount of organic substances attached (%) to each platinum catalyst afterward was used. The measuring device and measuring conditions used for the LC/UV chromatographic analysis are as follows.
LC system: Shimadzu model number "LC-20A"
Column: Inertsil ODS-3
Column temperature: 45°C
Mobile phase: A-0.1 vol% phosphoric acid aqueous solution, B-acetonitrile Injection volume: 10 μL
Detection wavelength: UV 240 nm.

(3) Decomposition of Platinum Catalyst First, an apparatus for measuring the resolution of a platinum catalyst will be described with reference to FIG. The platinum catalyst piece 14 was placed in a glass ampoule tube 15 (φ15 mm) having a shape that allows air to pass therethrough such that the thickness direction was parallel to the air traveling direction. Further, 5 g of the oligomer 16 was arranged on the upstream side of the platinum catalyst piece 14. By connecting an air pump (not shown) to the upstream part 17 of the ampoule pipe 15 and installing a coiled glass tube 19 (φ5 mm) in the downstream part 18 of the ampoule pipe, air is sent from the upstream side and undecomposed in the downstream side. The oligomer 16 has a structure capable of collecting the oligomer 16 (in the figure, the flow of air is indicated by a dashed arrow). Further, the ampule tube 15 was provided with a heater 20, and the coil-shaped glass tube 19 was arranged in the cooling tank 21 for precipitating undecomposed oligomer. Next, a method for measuring the resolution of the platinum catalyst will be described. A coil in the cooling tank 21 in which the ampoule tube 15 is heated to 230° C. by the heater 20 and 10 m ³ of air is sent from the upstream portion 17 into the ampoule tube 15 at a flow rate of 0.01 m ³ /sec and kept at 0° C. The mold glass tube 19 was passed through. Then, the mass of the glass tube 19 was measured, and the mass (g) of the oligomer 16 was calculated by subtracting the mass of the glass tube 19 in advance before the measurement. Using the obtained value, the decomposing ability (%) of the platinum catalyst was calculated by the following formula 1. The oligomer 16 used here is a mixture of a monomer and an oligomer generated by heat setting in the production of a polyethylene terephthalate film, and terephthalic acid (TPA), monohydroxyethyl terephthalate, when all the components are 100% by mass. The acid (MHET), bishydroxyethyl terephthalic acid (BHET), and their cyclic trimers are contained in a total amount of 99% by mass or more.
Formula 1: Platinum catalyst resolution (%) = (5-precipitated oligomer amount) x 100/5.

(4) Half Value Days The small pieces of platinum catalyst were again introduced into the heat fixing chamber of the tenter device to produce a polyethylene terephthalate film. Ten days after the start of production, a small piece of the platinum catalyst was taken out, the resolution was measured by the method described in "(3) Decomposition of platinum catalyst", and then the piece was returned to the heat fixing chamber again. After that, the same operation was repeated every 10 days until the resolution of the platinum catalyst piece became 50% or less, and the number of days until the resolution became 50% or less was taken as the half value number of days. However, when the resolution measured by the method described in "(3) Platinum catalyst resolution" after washing was 50% or less, the half value days was set to 0.

(5) Utility of Cleaning Method The utility of the cleaning method was evaluated by the following four items. When all the items are satisfied, A, when the three items are satisfied, B, when the two items are satisfied, C, when one item is satisfied, D, and when all the items are not satisfied and cleaning is not possible, E, A to D Was passed.
Item 1. The amount of adhered inorganic substances after cleaning was 65% or less before cleaning.
Item 2. The amount of organic substances attached after washing was 5% or less.
Item 3. The decomposing ability of the platinum catalyst after washing was 85% or more.
Item 4. The number of half-value days was 170 days or more.

(6) Pressure loss of platinum catalyst (%)
A gas valve and a gas cylinder were attached to a glass ampoule tube (φ15 mm), and the air was circulated by adjusting the flow rate with the gas valve so that the wind speed at the outlet of the ampoule tube was 0.05 m ³ /sec. Next, a small piece of platinum catalyst was placed in the ampoule tube, air was circulated at the same flow rate, and the wind speed Y (m ³ /sec) at the outlet of the ampoule tube was measured. Using the obtained Y, the pressure loss amount (%) of the platinum catalyst was calculated by the following formula 2. The lower the pressure loss amount, the more the function as a filter is maintained.
Formula 2: Platinum catalyst pressure loss (%)=(0.05−Y)×100/0.05.

(7) Weight of platinum catalyst filter A platinum catalyst filter having a thickness of 11 mm was cut into a size of 100 mm×100 mm, the mass (g) was measured, and the weight (g/cm ³ ) was calculated by the following formula 3.
Formula 3: A basis weight (g/cm ³ )=mass (g)/10×10×1.1.

(Example 1)
The used platinum catalyst pieces were dipped in triethylene glycol and heated to 265°C. Then, while maintaining the temperature, triethylene glycol was circulated for 16 hours to perform a cleaning treatment. After the completion of the washing treatment, the temperature of triethylene glycol was lowered to room temperature (25° C.) and discarded, and the platinum catalyst pieces were immersed in 80° C. water and subjected to ultrasonic treatment for 90 minutes. Each item of the platinum catalyst pieces thus obtained was evaluated. The evaluation results are shown in Table 1.

(Examples 2 to 7, Comparative Examples 1 to 5)
The washing treatment, ultrasonic treatment, and evaluation of each item were performed in the same manner as in Example 1 except that the thickness of the platinum catalyst piece, the solvent and the temperature in the washing treatment were as shown in Table 1. The evaluation results are shown in Table 1. In Comparative Example 2, since the cleaning treatment was impossible due to volatilization of triethylene glycol, evaluation of each item except the usefulness of the cleaning method was not performed.

(Examples 8 to 11)
Prior to washing, the used platinum catalyst pieces were roasted in the same manner as in Examples 1, 4 to 6 except that the used platinum catalyst pieces were roasted in air at 500° C. for 3 hours in an oven, and sonication, and Each item was evaluated. The evaluation results are shown in Table 1.

(Reference example 1)
Each item was evaluated without washing the platinum catalyst. The evaluation results are shown in Table 1.

In the table, TEG represents triethylene glycol and DEG represents diethylene glycol (these correspond to alcohol solvent A). The sodium hydroxide aqueous solution having a concentration of 20 mass% used in Comparative Example 4 had a boiling point of 100° C. because sodium hydroxide solid (melting point: 318° C.) was dissolved in water (boiling point: 100° C.). The nitric acid aqueous solution with a concentration of 30% by mass used in Comparative Example 5 has a boiling point of 82°C to 121°C depending on the concentration, so 82°C was used as the boiling point.

According to the present invention, it is possible to provide a method for cleaning a platinum catalyst filter, which can regenerate a platinum catalyst filter having a reduced oligomer decomposing property due to the attachment of a compound.

1 Platinum Catalyst Filter 2 Fixture 3 Frame 4 Tenter Device 5 Heat Fixing Zone 6 Films 7a, 7b Nozzle 8 Air Circulation Fan 9 Air Circulation Path 10 Steam Heater 11 Filter 12 Platinum Catalyst Filter 13 Attached to Frame 13 Electric Heater 14 Platinum Catalyst Pieces 15 ampoule tube 16 oligomer 17 upstream part (of ampoule tube) 18 downstream part (of ampoule tube) 19 glass tube 20 heater 21 cooling tank

Claims (11)

When the alcohol solvent having a boiling point of more than 250° C. is alcohol solvent A and the boiling point of the alcohol solvent A is X° C., the platinum catalyst filter is washed with the alcohol solvent A of 250° C. or more and less than X° C., platinum. Cleaning method of catalyst filter. The method for cleaning a platinum catalyst filter according to claim 1, wherein the alcohol solvent A contains triethylene glycol as a main component. The method for cleaning a platinum catalyst filter according to claim 1 or 2, wherein the platinum catalyst filter is roasted at a temperature of 300°C or higher and 600°C or lower and then washed. The platinum catalyst filter cleaning method according to any one of claims 1 to 3, wherein a weight of the platinum catalyst in the platinum catalyst filter is 0.3 g/cm ³ or more and 2.0 g/cm ³ . The platinum catalyst filter cleaning method according to any one of claims 1 to 4, wherein the platinum catalyst filter has a thickness of 5 mm or more and 30 mm or less. At least one of an organic substance and an inorganic substance adheres to the platinum catalyst filter, and the method for cleaning a platinum catalyst filter according to any one of claims 1 to 5, wherein: The method for cleaning a platinum catalyst filter according to claim 6, wherein an organic matter is attached to the platinum catalyst filter, and the organic matter is a component derived from polyethylene terephthalate. The method for cleaning a platinum catalyst filter according to claim 7, wherein the component derived from polyethylene terephthalate contains at least one of terephthalic acid, monohydroxyethyl terephthalic acid, and bishydroxyethyl terephthalic acid as a constituent unit. The platinum catalyst according to claim 7 or 8, wherein an inorganic substance is attached to the platinum catalyst filter, and the inorganic substance is at least one of silicon oxide, phosphorus oxide, and sulfur oxide. How to clean the filter. A stretching step of stretching a sheet in at least one direction using a tenter device having a platinum catalyst filter washed by the method for washing a platinum catalyst filter according to any one of claims 1 to 9 in an air circulation path. And a method for producing a film. A tenter device comprising a platinum catalyst filter cleaned by the method for cleaning a platinum catalyst filter according to any one of claims 1 to 9 in an air circulation path.

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