TWI519580B - Cellulose acylate solution, producing method thereof, and solution casting method - Google Patents

Description

Cellulose telluride solution, manufacturing method thereof and solution film forming method

The present invention relates to a cellulose halide solution, a method for producing the same, and a method for forming a solution.

As is well known, the solution film forming method is a method in which a dope in which a polymer is dissolved in a solvent is cast on a support to form a cast film, and the cast film is peeled off as a wetting film and dried to thereby produce a film. A cellulose oxime film which is often used for optical purposes is produced by this solution film forming method. In recent years, with the rapid market expansion of liquid crystal displays, the demand for cellulose oxime films which constitute a viewing angle expansion film or a polarizing plate protective film of a liquid crystal display has rapidly increased. Therefore, it is necessary to greatly increase the amount of production of the cellulose oxime film from the existing equipment.

In order to increase the film production by the existing solution film forming apparatus, the belt or the drum as a support is rotated at a higher speed. Further, the casting of the dope and the peeling of the casting film are repeatedly performed on the support, and the number of times of repetition per unit time increases with the production speed of the acceleration film. There is a variation in the composition of the dope or the casting conditions, the peeling conditions, and the like, but the support is more contaminated with the production speed of the accelerated film.

As a contamination of the support, it is confirmed that the substance contained in the cast film is gradually increased and becomes dirty so as not to be visually confirmed. In the following description, this confirmed contamination phenomenon is referred to as precipitation. As a method of preventing this precipitation, various proposals have been made so far. For example, Japanese Patent Publication No. 2006-199029 discloses that a concentration of a compound extracted from a cellulose sulphate by a specific extraction condition and a concentration of calcium, magnesium, sulfuric acid, or the like contained in the cellulose mash solution are in a specific range. A method for producing a cellulose oxime film. Thus, the manufacturing method of Japanese Laid-Open Patent Publication No. 2006-199029 reduces the amount of contamination generated on the drum.

Further, in Japanese Laid-Open Patent Publication No. 2008-063403, precipitation is prevented by setting the ratio of the mass of the cellulose halide to the mass of magnesium to a predetermined range. Further, in Japanese Laid-Open Patent Publication No. 2009-161702, the amount of calcium, the amount of magnesium, and the amount of sulfuric acid in the dope are within a predetermined range, and the compound having a predetermined skeleton is contained in the dope. Thereby, precipitation is suppressed, and film yellowing is prevented.

It is described in Japanese Patent Laid-Open Publication No. Hei. No. 2006-199029 that it is possible to prevent precipitation by using a cellulose ruthenium having a low concentration of calcium. However, precipitation occurs sometimes by the method of Japanese Patent Laid-Open Publication No. 2006-199029. The method of JP-A-2008-063403 and JP-A-2009-161702 may prevent precipitation. However, even if precipitation is caused by this method, it cannot be said that the method of completely suppressing precipitation. Further, the so-called cooling flow delay of cooling and solidifying the cast film on the support is particularly easy to occur. That is, the conventional cleaning method also effectively suppresses precipitation, but there are also components that cannot be removed.

Accordingly, it is an object of the present invention to provide a cellulose oxime solution which inhibits the generation of precipitation, a method for producing the same, and a method for forming a solution.

In order to solve the above problems, the cellulose oxime solution cast by a solution film formation of the present invention comprises a cellulose oxime compound, a solvent of the cellulose oxime compound, and a fatty acid ester of 0.01% or less. Quality ratio. The molecular weight of the fatty acid ester is in the range of 500 or more and 1,000 or less. The methylene group accounts for at least 80% of the aforementioned molecular weight.

The cellulose halide solution exhibits a particularly remarkable effect when the aforementioned cellulose halide is a deuterated cellulose obtained from conifers.

Further, the method for producing a cellulose halide solution of the present invention is a method for producing a cellulose halide solution in which a cellulose vapor film is formed by casting a solution onto a support. The method for producing a cellulose halide solution of the present invention comprises a preparation step (A step) and a mass ratio adjustment step (step B). In the step A, a cellulose halide solution having a hydrogen ion index pH adjusted to a range of 3 or more and 5 or less is prepared. In the step B, the mass ratio of the fatty acid ester is made 0.01% or less by heating the cellulose mash solution prepared in the above step A and maintaining the temperature in the range of 80 ° C to 90 ° C. The molecular weight of the fatty acid ester is in the range of 500 or more and 1,000 or less. The methylene group accounts for at least 80% of the aforementioned molecular weight.

It is preferred to dissolve the cellulose oxime in a solvent having a hydrogen ion index pH of 3 or more and 5 or less, thereby preparing a cellulose oxime solution having a hydrogen ion index pH of 3 or more and 5 or less.

In the above step B, it is preferred to maintain the temperature by heating for 30 minutes or more and 240 minutes or less.

When the cellulose oxime is a sputum of cellulose obtained from conifers, the above-described method for producing a cellulose oxime solution has a particularly remarkable effect.

Further, the solution film forming method of the present invention includes a preparation step (A step), a mass ratio adjustment step (B step), a casting step (C step), and a peeling/drying step (D step). In the step A, a cellulose halide solution having a hydrogen ion index pH adjusted to a range of 3 or more and 5 or less is prepared. In the step B, the mass ratio of the fatty acid ester is set to 0.01% or less by heating the cellulose halide solution prepared in the above-mentioned step A and maintaining the temperature in a range of from 80 ° C to 90 ° C. The molecular weight of the fatty acid ester is in the range of 500 or more and 1,000 or less. The methylene group accounts for at least 80% of the aforementioned molecular weight. Step C The foregoing cellulose halide solution obtained in the above step B is cast on a support. Step D The film formed of the cellulose halide solution in the above-mentioned step C is peeled off from the aforementioned support and dried.

According to the present invention, precipitation in a solution film formation can be suppressed.

<solution film forming method>

The solution film forming method of the present invention is carried out, for example, by the solution film forming apparatus 10 shown in Fig. 1. The solution film forming apparatus 10 includes a casting device 15, a tenter 17, a roll drying device 21, and a winding device 27 in this order from the upstream side. The casting device 15 forms a polymer film (hereinafter simply referred to as "film") 12 from a cellulose oxime solution (hereinafter referred to as "dope") in which a cellulose hydrate of a polymer component is dissolved in a solvent. The tenter 17 is dried by the side of each side of the film 12 held by the holding member 16. The roll drying device 21 is dried while supporting the film 12 by a plurality of rolls 20. Further, a slitter (not shown) may be disposed at a position downstream of the tenter 17 to cut off the holding traces of the respective side portions held by the holding member 16 of the tenter 17. The winding device 27 winds the film 12 around the core and forms a roll.

In the present specification, the solvent content rate (unit: %) is a value based on the dry amount. Specifically, when the mass of the solvent is x and the mass of the film 12 is y, it is {x/(yx)}. ×100 is determined as a percentage.

The casting device 15 includes a drum 30 as a casting support, and a casting die 35 that flows out of the dope 11 is provided above the drum 30. The dope 11 is continuously discharged from the casting die 35 to the circumferential surface of the rotating drum 30, whereby the dope 11 is cast on the drum 30 to form a casting film 36. In Fig. 1, a symbol PC is added at a position where the dope 11 starts to come into contact with the drum 30 (hereinafter referred to as "casting position").

The drum 30 is provided with a temperature controller (not shown) that controls the temperature of the peripheral surface. The temperature of the casting film 36 is adjusted by the drum 30 which controls the temperature of the peripheral surface. For example, when the cooling flow is delayed, if the circumferential surface temperature is in the range of -15 ° C or more and 10 ° C or less, the casting film 36 is cooled and gelled. The cast film 36 is solidified to a degree of transport by the gelation. When the circumferential temperature of the drum 30 is -15 ° C or more and 10 ° C or less and is extremely low, precipitation is particularly likely to occur by a conventional method. On the other hand, according to the present invention, the dope 11 to be described later is used, so that precipitation is less likely to occur even when the cooling flow is delayed.

Further, as the casting support, an endless belt (not shown) formed in a ring shape may be used instead of the drum 30. When a belt is used as the casting support, the belt is wound around the circumferential surface of a pair of rolls (not shown) that rotate in the circumferential direction. At least one of the pair of rolls may be a drive roll having a drive mechanism. The belt in contact with the circumferential surface is conveyed by the driving roller rotating in the circumferential direction. With this transfer, the belt circulates and continuously travels in the long side direction. When the belt is used as the casting support, a temperature controller (not shown) for controlling the circumferential temperature of the roller is provided on the pair of rollers, and the belt contacting the circumferential surface of the roller is controlled by controlling the circumferential temperature of the roller. The temperature is OK.

Regarding the dope 11 from the casting die 35 to the drum 30, a so-called liquid bead is provided with a decompression chamber (not shown) upstream of the rotation direction of the drum 30. The decompression chamber sucks the atmosphere of the upstream side region of the concentrated liquid 11 that has flowed out and decompresses the aforementioned region.

The casting film 36 is reinforced to such an extent that it can be conveyed to the tenter 17, and then peeled off from the drum 30 in a state containing a solvent. The cooling flow is delayed, and it is preferable to perform peeling during the range in which the solvent content of the casting film 36 is 150% by mass or more and 280% by mass or less.

At the time of peeling, the film 12 is supported by a peeling roller (hereinafter referred to as "peeling roll") 37, and the peeling position PP at which the casting film 36 is removed from the drum 30 is kept constant. The peeling roller 37 may be a driving roller that has a driving mechanism and rotates in the circumferential direction. The casting of the dope 11 and the peeling of the casting film 36 are repeatedly performed in the rotating drum 30.

A blowing device (not shown) may be disposed on the conveying path between the casting device 15 and the tenter 17. The film 12 is dried by blowing air from the air blowing device.

The stripped cast film 36, that is, the film 12 is guided to the tenter 17. The holding member 16 of the tenter 17 is set as a clip. However, since the film 12 has a high solvent content rate, if it is held by a clip, there is a problem that the film 12 is broken. In this case, a needle is used as the holding member 16. The needle holds the membrane 12 by puncturing the membrane 12.

The tenter 17 is held by the holding member 16 while being conveyed in the longitudinal direction by the holding member 16, and the tension in the width direction is imparted to expand the width of the film 12. The tenter 17 is formed with a preheating zone, a stretching zone, and a relaxation zone in this order from the upstream side. In addition, the relaxation zone may not be available.

The tenter 17 includes a pair of guide rails (not shown) and a chain (not shown). The guide rails are disposed on both sides of the conveying path of the film 12, and the pair of guide rails are disposed at predetermined intervals. The rail spacing is constant in the preheating zone and gradually widens towards the downstream in the stretching zone and is constant in the relaxation zone. In addition, the rail spacing of the slack zone may taper toward the downstream.

The chain is hung on the drive sprocket and the driven sprocket (not shown), and is movably mounted along the guide rail. A plurality of holding members 16 are attached to the chain at predetermined intervals. The retaining member 16 is cyclically moved along the guide rail by the rotation of the drive sprocket.

The holding member 16 starts to hold the guided film 12 near the entrance of the tenter 17, and moves toward the outlet to release the holding near the outlet. The retaining member 16 that has been unretained moves again to the vicinity of the inlet and re-maintains the guided film 12.

The preheating zone, the stretching zone, and the relaxation zone are formed into a space by sending dry air from the duct 31, and there is no clear boundary. The duct 31 is disposed above the transport path of the membrane 12. The duct 31 has a slit for sending dry air, and is supplied from a blower (not shown). The blower sends dry air adjusted to a predetermined temperature or humidity to the duct 31. The duct 31 is disposed such that the slit faces the transport path of the film 12. Each of the slits has a shape elongated in the width direction of the film 12, and is formed at a predetermined interval in the transport direction. Further, a duct having the same structure may be provided below the transport path of the film 12, or may be provided above and below the transport path of the film 12.

The side transfer film 12 of the tenter 17 is dried by the dry air from the duct 31, and the width is changed by the holding member 16 at a predetermined timing.

The temperature, humidity, and the like of the internal atmosphere of the roll drying device 21 are adjusted by an air conditioner (not shown). In the roll drying device 21, the film 12 is wound around a plurality of rolls 20 to be conveyed. The solvent is also evaporated from the membrane 12 in the roll drying device 21. In the roll drying device 21, the drying process is carried out until the solvent content is 5% by mass or less.

When the film 12 is sent to the winding device 27, it is wound into a roll shape. Further, in order to cause the film 12 to exhibit the target characteristics, a tenter (not shown) may be further disposed downstream of the roll drying device 21. This tenter has the same structure as the tenter 17.

The obtained film 12 can be used as an optical film. The optical film is, for example, a protective film of a polarizing plate or a retardation film.

<dope>

The amount of the fatty acid ester represented by the following formula (1) is reduced as much as possible in the dope 11. Specifically, in the present invention, the mass ratio of the fatty acid ester of the formula (1) in the dope 11 is suppressed to 0.0100% or less. Thereby, precipitation on the support can be suppressed not only in the dry casting but also in the cooling gelation casting. In the formula (1), R ¹ and R ^{2 each} represent an alkyl group. Here, the molecular weight of the fatty acid ester of the formula (1) is in the range of 500 or more and 1,000 or less, and the methylene group (-CH ₂ -) accounts for at least 80% of the molecular weight.

[Chemical Formula 1]

It is more preferable that the mass ratio of the fatty acid ester of the formula (1) in the dope 11 is 0.0010% or less. Further, the smaller the mass ratio of the fatty acid ester of the formula (1), the better, and it is preferably 0 (zero). However, if the mass ratio is to be infinitely close to 0 (zero), the mixing process from the mixing device 41 (refer to FIG. 2) to the heating device 45 (refer to FIG. 2) in the manufacturing method of the dope 11 to be described later is repeatedly performed. The heating process has a large number of repetitions, so it cannot be said to be economically preferable.

The number of carbon atoms (C number) of the fatty acid ester of the formula (1) is preferably 29 or more, and preferably 40 or more and 70 or less. That is, (carbon number of R ¹ ) + (carbon number of R ² ) is preferably 29 or more, and 40 or more and 70 or less is preferable.

When the cellulose oxime is obtained by deuteration of the cellulose obtained from the conifer, the fatty acid ester of the formula (1) is particularly rich in content, and is liable to cause precipitation. Therefore, when a cellulose halide obtained by deuteration of cellulose obtained from conifers is used as a polymer component of the dope 11, the content of the fatty acid ester of the formula (1) in the dope 11 is lowered and the mass is The ratio suppression is 0.01% or less, whereby the inhibitory effect of precipitation is particularly remarkable.

The ratio of the carboxylic acid esterified cellulose hydroxyl group of the cellulose halide, that is, the degree of substitution of the thiol group (hereinafter referred to as "thiol substitution degree") satisfies all the conditions of the following formulas (1) to (3). . Further, in (1) to (3), both A and B are thiol substitution degrees, the fluorenyl group in A is an ethyl fluorenyl group, and the fluorenyl group in B is a carbon number of 3 to 22.

2.5 A+B 3.0 (1)

0 A 3.0 (2)

0 B 2.9 (3)

The glucose unit constituting cellulose and performing β-1,4 bonding has a free hydroxyl group at the 2, 3, and 6 positions. The cellulose halide is a polymer in which a part or all of the cellulose hydroxyl group is esterified and a hydrogen of a hydroxyl group is substituted into a mercapto group having a carbon number of 2 or more. Further, when one of the hydroxy groups in the glucose unit is esterified to 100%, the degree of substitution is 1, so that when it is a cellulose oxime, if the hydroxyl groups at the 2, 3, and 6 positions are each esterified by 100%, The degree of substitution becomes 3.

Here, in the glucose unit, the degree of substitution of the thiol group at the 2-position of the thiol group at the 2nd position is set to DS3, and the degree of substitution of the thiol group at the 6-position is set to DS6, and is determined by "DS2+DS3+DS6". The degree of substitution of all thiol groups determined is preferably from 2.00 to 3.00, more preferably from 2.22 to 2.90, and further preferably from 2.40 to 2.88. Further, "DS6/(DS2+DS3+DS6)" is preferably 0.32 or more, more preferably 0.322 or more, and further preferably 0.324 to 0.340.

The thiol group may be used alone or in combination of two or more. When the fluorenyl group is two or more kinds, one of them is preferably an acetamino group. The sum of the substitution ratios of the thiol groups of the hydrogens of the hydroxyl groups of the 2, 3, and 6 positions is set to DSA, and the sum of the substitution degrees of the thiol groups other than the acetamidine group at the 2, 3, and 6 positions is set to In the case of DSB, the "DSA+DSB" value is preferably 2.2 to 2.86, and particularly preferably 2.40 to 2.80. A DSB of 1.50 or more is preferred, and a 1.7 or more is particularly preferred. Further, it is preferable that 28% or more of DSB is a hydroxyl group at the 6-position, but it is preferably 30% or more, more preferably 31% or more, and particularly preferably 32% or more. Further, the "DSA+DSB" value of the 6-position of the cellulose halide is preferably 0.75 or more, more preferably 0.80 or more, and particularly preferably 0.85 or more. By using the cellulose oxime compound as described above, it is possible to obtain a preferred polymer solution for preparing a polymer solution used for forming a solution, and to produce a polymer solution having a low viscosity and a low viscosity. In particular, when a non-chlorine organic solvent is used, the cellulose halide described above is preferred.

The fluorenyl group having 2 or more carbon atoms may be an aliphatic group or an aryl group, and is not particularly limited. For example, there may be an alkylcarbonyl ester of cellulose, an olefinic carbonyl ester or an aromatic carbonyl ester, an aromatic alkylcarbonyl ester or the like, which may each have a further substituted group. Examples thereof include a fluorenyl group, a butyl fluorenyl group, a pentamidine group, a hexyl fluorenyl group, a decyl group, a decyl group, a dodecyl fluorenyl group, a tridecyl fluorenyl group, a tetradecane fluorenyl group, a hexadecane group, an octadecane group. Anthracenyl, isobutyl fluorenyl, tert-butyl fluorenyl, cyclohexanecarbonyl, oleoyl, benzhydryl, naphthalenecarbonyl, cinnamyl, and the like. Among them, a propyl fluorenyl group, a butyl decyl group, a dodecyl fluorenyl group, an octadecyl fluorenyl group, a tert-butyl fluorenyl group, an oil fluorenyl group, a benzamidine group, a naphthalene carbonyl group, a cinnamyl group, etc. .

<Manufacturing equipment and manufacturing method of concentrated liquid>

Hereinafter, a manufacturing apparatus and a manufacturing method of the dope 11 will be described. The dope 11 uses cellulose halide and a solvent as essential constituent elements. However, in consideration of the process of producing the film 12 and the storage, transportation, and use of the film 12, the plasticizer is mostly contained in the dope 11. Therefore, in the following description, the case where the plasticizer is also used as the dope component is taken as an example. Further, in the following description, a case where TAC (triacetate cellulose) is used as the cellulose halide is taken as an example, but as described above, the cellulose halide is not limited to TAC. Further, in the present embodiment, a mixture of dichloromethane, methanol and butanol is used as a solvent.

As shown in FIG. 2, the dope production facility 40 includes a mixing device 41, a dissolution device 42, a concentration device 43, a recovery/purification device 44, and a heating device 45.

The mixing device 41 includes a housing (not shown), a stirrer (not shown), and a temperature controller (not shown). The housing accommodates the solvent 49 of the TAC 48, TAC 48, and the plasticizer 50. The agitator is provided in the housing portion, and includes a stirring blade (not shown) and a driving mechanism (not shown) that rotationally drives the agitating blade. The agitating blades are housed inside the housing. The temperature controller controls the temperature inside the housing.

When the TAC 48, the solvent 49, and the plasticizer 50 are fed, the mixing device 41 rotates the stirring blade while controlling the temperature inside the housing.

In the present embodiment, a static mixer is used as the dissolution device 42. However, the dissolution device 42 is not limited to a static mixer. The static mixer used in the present embodiment is a well-known static mixer. The static mixer includes a liquid supply tube (not shown) through which the mixture of the TAC 48 of the mixing device 41, the solvent 49 and the plasticizer 50 passes, a temperature control unit (not shown) provided on the outer periphery of the liquid supply tube, and A plurality of elements (not shown) arranged in the liquid supply direction are disposed inside the liquid supply tube. Each element is formed by twisting a rectangular plate by 180°. The temperature control unit has a sleeve covering the outer circumference of the liquid supply tube and a temperature controller for controlling the temperature of the sleeve.

When a mixture of TAC 48, solvent 49, and plasticizer 50 is fed, the dissolution device 42 controls the temperature inside the liquid supply pipe while guiding the mixture downstream. The element applies shear to the mixture directed to the downstream.

The liquid supply pipe L1 downstream of the dissolution device 42 branches, and the liquid supply pipe L2 of one of the branches is connected to the concentration device 43, and the heating device 45 is connected to the other liquid supply pipe L3. A three-way valve 51 is provided at the branch position.

The concentrating device 43 is a well-known flash unit, but is not limited thereto. The flash unit includes a housing (not shown) and a nozzle (not shown) that flashes (sprays) the concentrated liquid 11 toward the inside of the housing. The accommodating portion accumulates the concentrated liquid 11 which is flashed from the nozzle. A pipe L4 connected to the recovery/refining device 44 is provided above the accommodating portion. A liquid supply pipe L5 is provided below the housing. The liquid supply tube L5 branches downstream of the dissolution device 42 and is connected to the liquid supply tube L3 connected to the heating device 45. The merging portion connecting the liquid supply tube L3 of the dissolution device 42 and the heating device 45 and the liquid supply tube L5 extending from below the accommodating portion of the concentrating device 43 is denoted by reference numeral PJ1 in Fig. 2 .

The recovery/purification device 44 includes a cooler (not shown) that is connected to the pipe L4 extending from the upper portion of the accommodating portion of the concentrating device 43 and cools the solvent guided from the concentrating device 43 in a gaseous state to form a liquid. Further, the recovery/purification device 44 includes a refining unit (not shown) that purifies the solvent when the solvent is introduced into the liquid by the cooler.

The refining section of the recovery/purification device 44 is connected to the mixing device 41. A liquid supply pipe L7 for feeding acetic acid 52 and a liquid supply pipe L8 for feeding sodium acetate 53 are connected to the refining section of the connection recovery/purification device 44 and the liquid supply pipe L6 of the mixing device 41, respectively. A valve 56 is provided in the liquid supply pipe L7 to which the acetic acid 52 is fed, and a valve 57 is provided in the liquid supply pipe L8 to which the sodium acetate 53 is fed. Each of the valves 56, 57 has an opening degree adjustment function for adjusting the opening degree.

The heating device 45 is provided as a static mixer which is substantially the same as the dissolution device 42. However, the liquid supply pipe (not shown) of the heating device 45 is longer than the liquid supply pipe (not shown) of the dissolution device 42, and the time remaining in the liquid supply pipe is longer than the liquid supply pipe remaining in the dissolution device 42. time. In the present embodiment, the length of the liquid supply pipe of the heating device 45 is set to be twice or more and three times or less the length of the liquid supply pipe of the dissolution device 42. Further, the length of the liquid supply pipe instead of the heating device 45 may be longer than or in addition to the state of the liquid supply pipe of the dissolution device 42, or the liquid supply pipe of the heating device 45 may be disposed downstream of the liquid supply pipe. The aspect of the circulating piping toward the upstream. The circulation pipe and the liquid supply pipe are circulated and flowed five to ten times in the liquid supply pipe of the heating device 45, whereby the residence time in the liquid supply pipe of the heating device 45 can be further extended.

The heating device 45 is connected to the solution film forming apparatus 10. However, the heating device 45 is not necessarily connected to the solution film forming apparatus 10. For example, the heating device 45 can be connected to the storage container for storing the dope 11 instead of the solution film forming apparatus 10.

The liquid supply pipe L3 between the merging portion PJ1 and the heating device 45 branches. A three-way valve 58 is provided at the branch position. The downstream end of the liquid supply pipe L9 branched from the liquid supply pipe L3 is connected to the liquid supply pipe L10 that connects the heating device 45 and the solution film forming apparatus 10. When the heating device 45 is not connected to the solution film forming apparatus 10 and is connected to the storage container for storing the dope 11, the downstream end of the branch liquid supply pipe L9 may be connected to the storage container.

In Fig. 2, the connection position of the branch liquid supply pipe L9 and the liquid supply pipe L10 downstream of the heating device 45, that is, the junction portion is denoted by the symbol PJ2. In the liquid supply tube L10 downstream of the heating device 45, a tube L11 for feeding sodium acetate 61 is connected at a position upstream of the merging portion PJ2. A valve 62 having an opening degree adjustment function for adjusting the opening degree is provided on the tube L11.

Hereinafter, a method of manufacturing a dope based on the dope manufacturing apparatus 40 will be described with reference to FIG. First, when the solvent 49 of TAC48 and TAC48 and the plasticizer 50 are sent to the mixing device 41, the mixing device 41 heats them and mixes them. Specifically, the housing portion of the mixing device 41 mixes the contained TAC 48, the solvent 49, and the plasticizer 50 by driving the agitator. The temperature controller controls the temperature inside the housing, thereby adjusting the temperature of the contained TAC 48, solvent 49, and plasticizer 50.

The mixture obtained by mixing in the mixing device 41 is sent to the dissolution device 42. If fed to the mixture, the dissolution device 42 dissolves the TAC 48 and the plasticizer 50 in the solvent 49 as the dope 11. The temperature of the dope 11 set when it is dissolved in the dissolution apparatus 42 is in the range of 20 ° C or more and 40 ° C or less.

It is determined that the concentration of the dope 11 is equal to or lower than a predetermined concentration. This concentration is the concentration of the solid content in the dope 11, and in the present embodiment is the mass ratio of TAC48 and plasticizer 50 in the dope 11. The predetermined concentration is set in accordance with the film 12 to be manufactured. When the concentration of the dope 11 is equal to or lower than a predetermined concentration, the dope 11 is sampled. When the concentration is not higher than the predetermined concentration, that is, higher than the predetermined concentration, the concentrated liquid 11 is sent to the concentration device 43. The concentrating device 43 is concentrated to a predetermined concentration or lower by flashing the dope 11. The concentrated concentrate 11 is sampled.

In the concentrating device 43, the solvent 49 which is flashed into a gas by the dope 11 is sent to the recovery/purification device 44. The recovery/purification device 44 cools the solvent 49 which is a gas, and purifies it as a liquid in order to improve the purity of the solvent 49 which becomes a liquid. As a purification method, for example, there is distillation.

In the present embodiment, the dope 11 is sampled from the liquid supply path between the merging portion PJ1 and the three-way valve 58 downstream of the merging portion PJ1 during both concentration and non-concentration. In Fig. 2, the symbol PS is attached at the sampling position. However, when the dope 11 is not concentrated, the dope 11 can be sampled at any portion of the liquid supply tubes L1, L3 provided from the dissolution device 42 over the three-way valve 58.

The mass ratio (content ratio) of the fatty acid ester of the formula (1) is determined by the sampled concentrated liquid 11 (symbol S1 of Fig. 3). Here, the mass ratio of the fatty acid ester of the formula (1) means the mass of the fatty acid ester of the formula (1) which is expressed in percentage (unit: %) with respect to the total mass of the dope 11, and is expressed by a percentage ( 1) The mass ratio of the fatty acid ester in the dope 11. Specifically, when the mass of the dope 11 is A and the mass of the fatty acid ester of the formula (1) is B, the mass ratio of the fatty acid ester is a value obtained by (B/A)×100. Further, the method for determining the mass ratio of the fatty acid ester of the formula (1) will be described later using other drawings.

When the mass ratio of the fatty acid ester is determined, it is determined whether or not the mass ratio is 0.01% or less. When the mass ratio of the fatty acid ester is 0.01% or less, the manufacturing process of the dope 11 is completed, and the dope 11 is supplied to the film forming process. Further, when the dope 11 contains an additive (not shown) different from the plasticizer 50, these additives may be added before being supplied to the film forming process.

When the mass ratio of the fatty acid ester is more than 0.01%, the sample 11 is again sampled. The hydrogen ion index pH of the concentrated liquid 11 is obtained by the sampled concentrated liquid 11 (symbol S2 of Fig. 3). In addition, the method of determining the hydrogen ion index pH of the dope 11 will be described later using other drawings.

When the hydrogen ion index pH of the dope 11 is determined, it is determined whether the obtained value satisfies 3 pH 5. When satisfied 3 pH At 5 o'clock, a heating process for heating the dope 11 is carried out.

When not satisfied 3 pH At 5 o'clock, it was evaluated whether it was any of pH < 3 and pH > 5. When the pH is <3, sodium acetate 53 is added to the solvent 49 sent to the mixing device 41, and the amount of sodium acetate 53 added is increased until it is 3 or more. When the pH is >5, acetic acid 52 is added to the solvent 49 sent to the mixing device 41, and the addition amount of the acetic acid 52 is increased until it becomes 5 or less. In this manner, the pH of the dope 11 is adjusted to a range of 3 or more and 5 or less. Further, the value of acetic acid 52 or sodium acetate 53 added in accordance with the pH of the dope 11 can be determined. By this value, the flow rate of the supply amount of acetic acid 52 or sodium acetate 53 with respect to the solvent 49 in the liquid supply tube L6 of the solvent 49 of the mixing device 41 may be set.

The heating device 45 performs heating while conveying the pH-adjusting liquid 11 downstream. This heating is carried out so that the temperature of the dope 11 is maintained in the range of 80 ° C or more and 90 ° C or less. By this heating, the mass ratio of the fatty acid ester of the formula (1) in the dope 11 is 0.01% or less. By the adjustment and heating of the pH, the dope 11 does not precipitate even if it is cast in the drum 30 (Fig. 1). According to this method, the TAC or the plasticizer does not decompose, or even if it is decomposed, it can be suppressed to a practically problem-free degree. Further, by this heating, the fatty acid ester of the formula (1) is decomposed into a fatty acid and an alcohol, but they do not precipitate.

The temperature adjustment of the dope 11 is performed by controlling the temperature of the sleeve covering the outer circumference of the liquid supply tube by the temperature controller. The temperature of the dope 11 set when heated in the heating device 45 is higher than the temperature in the dissolution device 42.

In the heating device 45, it is preferable to set the temperature of the dope 11 in the range of 80 ° C or more and 90 ° C or less in the range of 60 minutes or more and 240 minutes or less. During this period, by maintaining the temperature of the dope 11 within the above range, the fatty acid ester of the formula (1) is more reliably decomposed. Thereby, precipitation can be prevented more reliably. The adjustment of the time to maintain the temperature has a method of adjusting the length of the liquid supply tube and a method of adjusting the liquid supply speed in the liquid supply tube. This temperature holding time is extremely long and is 5 times or more and 10 times or less the length of time in which the dope 11 is heated in the dissolution device 42. For example, the heating time in the dissolution device 42 is 10 minutes or more and 60 minutes or less, which is extremely shorter than the time in the heating device 45.

Further, it is preferable to measure the pH by sampling the concentrated liquid 11 heated by the heating device 45. When the pH meets 4.5 pH At 5.5, the manufacturing process of the dope 11 is completed, and the dope 11 is guided to the solution film forming apparatus 10 or the storage container. When the pH is less than 4.5, it is preferred to add sodium acetate 61 to the dope 11 and adjust the pH to 4.5 or more. Further, when the cellulose halide is used as the polymer component, there is almost no case where the pH of the dope 11 is more than 5.5.

In addition, the mass ratio of the fatty acid ester of the formula (1) can be determined by the concentration of the concentrated liquid 11 heated by the heating device 45 before the sampling for the pH measurement as described above, and it is confirmed that it is 0.01% or less.

A method of obtaining the mass ratio (symbol S1 of Fig. 3) of the fatty acid ester of the formula (1) by the sampled dope 11 will be described with reference to Fig. 4 .

The sampled dope 11 contains a plasticizer 50. Depending on the type of the plasticizer 50, the mass ratio of the fatty acid ester of the formula (1) may not be accurately measured. Therefore, in the present embodiment, the plasticizer 50 is removed from the sampled dope 11, and the removal is performed by methanol extraction.

A film is formed from the dope 11 from which the plasticizer 50 is removed. Further, in the present embodiment, a film having a thickness of 80 μm is cast and dried. The drying conditions were set to 140 ° C for 30 minutes. Further, the film temperature and time as the drying conditions are not limited to 140 ° C for 30 minutes, and may be the same as the drying conditions in the solution film forming apparatus 10 as long as the TAC 48 is not sufficiently dried to be decomposed.

The film is ground by a mixer or a grinder, and chips are produced. The size of the chips is not particularly limited, and may be, for example, about 5 mm × 5 mm.

Soxhlet extraction was carried out with 10 g of chips. The solvent for Soxhlet extraction is preferably toluene. The extraction was carried out 50 times or more under normal pressure with 100 mL (ml) of the toluene. Concentration was repeated for 50 extractions of 100 mL of toluene (corresponding to an extract). The concentrate obtained by concentration is measured. The mass of the concentrate obtained by the measurement was set to A (g). The concentrate was diluted with 1 mL of toluene, and the dilution obtained by dilution was supplied to a gas chromatography mass spectrometer (GCMS). As the column of the GCMS, for example, DB-HT5 manufactured by Agilent Co., Ltd. can be mentioned. After holding at 100 ° C for 1 minute, the temperature was raised at a rate of 15 ° C / minute, and then held at 400 ° C for 9 minutes to carry out measurement.

A standard of the fatty acid ester of the formula (1) is prepared and supplied to the GCMS. When the specimen is measured by GCMS, the carbon number is approximately in the range of 29 or more and 65 or less. Therefore, based on the measurement result of the specimen, the area S1 of the portion corresponding to the carbon number of 40 or more and 65 or less in the spectrum obtained by the GCMS-based measurement is obtained, and the area S1 is obtained by dividing the entire area S2. And the value is set to the mass ratio R1 of the fatty acid ester of the formula (1) in the concentrate.

Further, the concentration of the plasticizer-removing concentrate 11 obtained by concentration of the toluene-based extraction and extraction liquid (hereinafter referred to as "concentration of the concentrate in the concentrate") X (unit; %). The concentration X of the concentrate in the dope is a value obtained by [A/{(10 g/B) × 100}] × 100. "10g" in the formula corresponds to 10g which is the quality of the chips used in the Soxhlet extraction. Further, B is the concentration of the solid component in the dope used to obtain the chips. The dope used to obtain the chips does not contain the plasticizer 50 because the plasticizer 50 is removed in advance. (10 g/B) × 100 is the mass (unit: g) of the dope used to obtain the chips. A/{(10 g/B) × 100} is a ratio of the mass of the aforementioned concentrate to the mass of the dope 11 from which the plasticizer 50 is removed.

The concentration X of the concentrate in the concentrate 11 is multiplied by the mass ratio R1 of the fatty acid ester of the formula (1) in the concentrate. The value of X × R1 is defined as the mass ratio of the fatty acid ester of the formula (1) in the dope 11.

Regardless of the removal of the plasticizer 50, when the plasticizer 50 is extracted with toluene, the extract obtained by Soxhlet extraction is subjected to known extraction such as liquid separation extraction, decantation, chromatography, etc., thereby removing plasticization from the extract. Agent 50.

Next, a method of determining the pH of the dope 11 (symbol S2 in Fig. 3) by the sampled dope 11 will be described with reference to Fig. 5 .

A film was formed from the sampled dope 11. Further, the thickness of the film is not particularly limited. The drying conditions at which the cast dope 11 was peeled off and dried were set to 140 ° C for 20 minutes. Further, the temperature and time of the film as the drying condition are not limited to 140 ° C and 20 minutes, but the drying is completed in a state where the solvent remains.

The film was washed with water. In the present embodiment, water washing is performed by the following method. First, 6.5 g of a film was added to methanol, and ultrasonic waves were applied to the methanol bath. The mass of methanol was set to 35 g. However, the mass of methanol may be added or subtracted depending on the quality of the film, or may be set to 35 g per 6.5 g of the film. The time to implement the ultrasonic wave is set to 3 hours. When the ultrasonic treatment was completed for 3 hours, the film was taken out from the methanol and placed in water. Ultrasonic waves were applied to the water bath. The mass of water was set to 22 g. Further, the quality of the water may be increased or decreased depending on the quality of the film, and may be set to 22 g per 6.5 g of the film supplied to the methanol bath. The time for performing the ultrasonic wave of the water bath was set to 3 hours. When the ultrasonic treatment for 3 hours is completed, the film is taken out from the water. The water from which the membrane was taken out was filtered, and the pH of the filtrate was measured. This pH is taken as the pH of the dope 11.

Further, a compound having a lower solubility with respect to the solvent 49 is carried into the cellulose halide as an impurity of cellulose as a main raw material. On the other hand, compounds derived from solvents-based petroleum usually do not contain such impurities. The cellulose halide contains a compound having a lower solubility relative to the solvent 49, as a component of the paraffin component contained in the pulp purified from cotton or the pulp refined from wood. In order to remove the compound, it is preferred to remove the paraffin component as much as possible in the stage of the slurry or the lint fiber, but the cost is too high or too time consuming. Since such a compound having a low solubility mostly contains an ester group, the ester is decomposed by a treatment at a high temperature, an acid or alkali treatment, an oxidation reduction, an enzyme treatment, or the like, and the molecular weight is 500 or less. Thereby, the content of this compound is controlled. Alternatively, such treatment may be carried out in any of the processes of manufacturing the dope 11, the process of making the cellulose halide, the process of making the slurry or the lint fiber after the dope 11 is manufactured.

Hereinafter, examples of the invention and comparative examples with respect to the invention will be given. The details are described in the first embodiment, and only the conditions different from the first embodiment are described in the other examples and comparative examples.

[Examples]

Two kinds of dope 11 were produced by the following conditions and methods by the dope manufacturing apparatus 40. This embodiment is set as the first embodiment.

The formulations of the two dopes are as follows.

<1st concentrated solution>

Cellulose acetate (sulfonic acid substitution degree of 2.85) 100 parts by mass

Triphenyl phosphate 13 parts by mass

Methylene chloride 384 parts by mass

Methanol 54 parts by mass

N-butanol 15 parts by mass

Light removal agent (AS972, average primary particle size 10nm) 0.03 parts by mass

<2nd concentrated solution>

Cellulose acetate (sulfonic acid substitution degree of 2.85) 100 parts by mass

Triphenyl phosphate 13 parts by mass

Dichloromethane 314 parts by mass

Methanol 44 parts by mass

N-butanol 12 parts by mass

The time during which the temperature and the holding temperature of the first dope 11 are heated and maintained in the heating device 45 are shown in the "temperature based on the heated dope" (unit: °C) column and the "time to maintain the temperature" (unit; Minutes in the column. In the first dope 11 sampled at the sampling position PS between the merging portion PJ1 and the three-way valve 58, the mass ratio of the fatty acid ester of the formula (1) is not 0.01% or less. Therefore, acetic acid 52 is added to the solvent 49, and the mass ratio of the fatty acid ester of the formula (1) is made 0.01% or less. The pH at which the first concentrated liquid 11 produced by adding acetic acid 52 was supplied to the heating device 45 is shown in the column of "hydrogen ion index pH" in Table 1. For confirmation, the first concentrated liquid 11 is sampled downstream of the heating device 45, and the mass ratio of the fatty acid ester of the formula (1) is obtained for the sampled first concentrated liquid 11. The mass ratio obtained is shown in the column of "mass ratio" (unit; %) in Table 1. Further, the second dope 11 is also produced by the same method and conditions as those of the first dope 11, and the same information is obtained, and thus the description thereof is omitted.

The film 12 is produced by the solution film forming apparatus 10 by co-casting the first and second dope 11 of the mass ratio of the fatty acid ester of the formula (1). These dopes 11 are co-cast after being filtered. Further, the co-casting is a three-layer co-casting, the first dope is used as a surface layer doping liquid exposed on the surface, and the second dope is used as a core layer doping liquid between the surface layers. In other words, co-casting is performed so that the first dope, the second dope, and the first dope are sequentially superposed. In the casting film 36, the layer composed of the first dope 11 is 3 μm, and the layer composed of the second dope 11 is 74 μm, and flows out from the casting die 35 to co-cast. Casting is performed using a casting die 35 having a feed head. Further, each of the dope 11 flows out of the casting die 35 while being heated to 35 °C. The circumferential temperature of the drum 30 was set to -7 °C. After the cast film 36 was peeled off, the film 12 was obtained by a tenter 17 and a roll drying device 21 at 120 ° C for 10 minutes.

The occurrence of precipitation in the drum 30 was evaluated. Specifically, the time until contamination (dirt) occurred on the circumferential surface of the drum 30 was evaluated based on the following criteria, and this was evaluated as precipitation. Visually confirm the occurrence of pollution. Further, A to D are practical ranges.

A; more than 48 hours

B; less than 48 hours over 24 hours

C; 12 hours or more and less than 24 hours

D; 10 hours or more and less than 12 hours

E; less than 10 hours

Instead of the conditions of the first embodiment, the temperature of the first and second concentrated liquids 11 and the time during which the temperature is maintained in the heating device 45 and the pH of the first and second concentrated liquids 11 supplied to the heating device 45 are taken as These conditions shown in Table 1 were implemented. The conditions and examples are shown in Table 1.

[Comparative example]

In the comparative example, in the dope sampled at the sampling position PS between the merging portion PJ1 and the three-way valve 58, the mass ratio of the fatty acid ester of the formula (1) is not more than 0.01%. However, acetic acid 52 was not added to the solvent 49. Further, heating by the first and second concentrated liquids of the heating device 45 is not performed. A film having a three-layer structure was produced by co-casting from the first and second concentrated liquids thus obtained.

10. . . Solution film making equipment

11. . . Concentrate

12. . . membrane

15. . . Casting device

16. . . Holding member

17. . . Tenter

20. . . Roll

twenty one. . . Roll drying device

27. . . Winding device

30. . . roller

31. . . catheter

35, 36. . . Casting die

37. . . Peeling roller (peeling roller)

40. . . Concentrate manufacturing equipment

41. . . Mixing device

42. . . Dissolution device

43. . . Concentrator

44. . . Recycling/refining unit

45. . . heating equipment

48. . . TAC (cellulose triacetate)

49. . . Solvent

50. . . Plasticizer

51, 58. . . Three-way valve

52. . . acetic acid

53, 61. . . Sodium acetate

56, 57, 62. . . valve

L1, L2, L3, L4, L5, L6, L7, L8, L9, L10, L11. . . Liquid supply tube

PC. . . Cast position

PJ1, PJ2. . . Confluence

PP. . . Peeling position

PS. . . Sampling position

S1. . . Find the mass ratio

S2. . . Find the pH

Fig. 1 is a schematic view showing a solution film forming apparatus for carrying out a solution film forming method of the present invention.

Fig. 2 is a schematic view showing a dope manufacturing apparatus for carrying out the method for producing a dope according to the present invention.

Fig. 3 is a flow chart showing a method of producing a dope according to the present invention.

Figure 4 is a flow chart for determining the mass ratio of fatty acid esters.

Fig. 5 is a flow chart for determining the hydrogen ion index pH of the dope.

48. . . TAC

50. . . Plasticizer

49. . . Solvent

S1. . . Find the mass ratio

S2. . . Find the pH

Claims (7)

A cellulose telluride solution cast by a solution film having the following: a cellulose halide; a solvent of the cellulose halide; and a mass ratio of a fatty acid ester of 0.01% or less, wherein the molecular weight of the fatty acid ester is In the range of 500 or more and 1,000 or less, the methylene group accounts for at least 80% of the above molecular weight. The cellulose oxime solution according to claim 1, wherein the cellulose oxime is a cellulose obtained by conifers. A method for producing a cellulose oxime solution which is formed by casting a film on a support and forming a cellulose oxime film, and has the following steps: (A) preparing a cellulose having a hydrogen ion index pH adjusted to a range of 3 or more and 5 or less a telluride solution; and (B) heating the cellulose halide solution prepared in the above step A, and maintaining the temperature in a range of from 80 ° C to 90 ° C, whereby the mass ratio of the fatty acid ester is 0.01% or less The molecular weight of the fatty acid ester is in the range of 500 or more and 1,000 or less, and the methylene group accounts for at least 80% of the molecular weight. The method for producing a cellulose oxime solution according to the third aspect of the invention, wherein the cellulose oxime compound is dissolved in a solvent having a hydrogen ion index pH of 3 or more and 5 or less to have a thickness of 3 or more and 5 or less. A range of hydrogen ion index pH cellulose mash solutions. The method for producing a cellulose halide solution according to claim 3, wherein the time during which the temperature is maintained by heating in the step B is 30 minutes or longer and 240 minutes or shorter. The method for producing a cellulose oxime solution according to claim 3, wherein the cellulose oxime is a cellulose obtained by conifers. A solution film forming method comprising the steps of: (A) preparing a cellulose halide solution having a hydrogen ion index pH adjustment in a range of 3 or more and 5 or less; (B) heating the aforementioned cellulose halide solution prepared in the aforementioned step A and The temperature is maintained in the range of 80° C. or higher and 90° C. or lower, whereby the mass ratio of the fatty acid ester is 0.01% or less, the molecular weight of the fatty acid ester is in the range of 500 or more and 1,000 or less, and the methylene group accounts for at least 80 of the above molecular weight. (C) casting the aforementioned cellulose halide solution obtained in the above step B onto the support; and (D) peeling off the film formed of the cellulose halide solution in the aforementioned step C from the support And dry.