JP5027718B2 - Thermoplastic resin body and method for producing the same - Google Patents

Description

  The present invention relates to a thermoplastic resin body, more specifically, a thermoplastic resin body in which the content of foreign matter such as gel is reduced, and a method for producing the same.

  Thermoplastic resin bodies (for example, thermoplastic resin films) are widely used as optical members used in image display devices such as liquid crystal displays, plasma displays, and organic EL displays, sensors such as infrared sensors, and optical waveguides. A thermoplastic resin body used as an optical member is required to have excellent optical characteristics such as light transmission characteristics, birefringence characteristics, and phase difference characteristics. In recent years, in addition to this, optical defects due to foreign substances are reduced as much as possible. There is a strong demand for this.

  One of the foreign matters that cause optical defects is a gel. By reducing the amount of gel contained in the thermoplastic resin body, the optical defects as an optical member can be reduced. However, the gel is an optional step that involves heating during polymerization of the thermoplastic resin and after polymerization until it finally becomes an optical member (pelletizing step, mixing step with other thermoplastic resins and additives, etc. Therefore, it cannot be reduced by a method such as simply cleaning the manufacturing environment, unlike foreign substances mixed in from the environment.

  In JP 2007-262399 A (Patent Document 1), a thermoplastic resin in a hot-melted state is filtered through a polymer filter, and the gel contained in the resin is physically removed to provide an optical member. A method for producing a thermoplastic resin suitable for the above-mentioned applications is disclosed. However, since this method does not always sufficiently remove the gel, it is desired to realize a method for removing the gel more effectively.

JP-A-2006-142715 (Patent Document 2) manufactures a molded article with less optical defects by optimizing the melt extrusion molding conditions of a thermoplastic resin to reduce the amount of gel generated during molding. A method is disclosed. However, in this method, the gel generated at the stage prior to resin molding, such as during polymerization, remains in the obtained resin body without being removed at all.
JP 2007-262399 A JP 2006-142715 A

  Then, this invention aims at provision of the manufacturing method of the thermoplastic resin body which can reduce effectively the quantity of foreign materials, such as a gel contained.

A method for producing a thermoplastic resin body according to the present invention includes a filtration step for a thermoplastic resin, and a molding step for melt-molding the resin that has undergone the filtration step or a resin composition containing the resin. a manufacturing method, as the filtration step, the solution is filtered for filtering the solution containing the resin, have rows and melt filtration the resin after the solution is filtered is filtered in a state in which the resin is thermally melted, said forming step In the method, the resin or the resin composition is melt-molded to obtain pellets of the resin or the resin composition .

  According to the method for producing a thermoplastic resin body of the present invention, the amount of foreign matter such as gel contained in the obtained thermoplastic resin body can be effectively reduced. Moreover, the optical defect which exists in the said member can be reduced by using the resin body obtained by the manufacturing method of the thermoplastic resin body of this invention as an optical member.

  According to the study by the present inventors, in melt filtration, a gel having a size larger than the filtration accuracy that should be removed may pass through the filter. The passage of the gel is considered to be due to the high deformability of the gel at a temperature at which the thermoplastic resin is in a melted state. In addition, to increase the filtration accuracy of the filter for the purpose of increasing the amount of gel removed, the gel is compressed and deformed by increasing the filtration pressure, so that a gel having a size larger than the filtration accuracy passes through the filter. This is considered to be a factor.

  In the method for producing a thermoplastic resin body of the present invention, solution filtration for filtering a solution of the resin is used as a technique for filtering the thermoplastic resin. Solution filtration can be performed with the gel deformability kept low because the resin is dissolved in a solvent, that is, at a temperature at which the solvent does not boil under filtration pressure. In the solution, the gel swells with the solvent. For this reason, in solution filtration, a gel having a size larger than the filtration accuracy is difficult to pass through the filter, and the gel can be efficiently removed. In the method for producing a thermoplastic resin body of the present invention, in consideration of the possibility that gels may be generated after solution filtration or foreign substances may be mixed in, the above-mentioned resin after solution filtration is further melt filtered. I do. In the method for producing a thermoplastic resin body of the present invention, the amount of foreign matter such as gel contained in the obtained thermoplastic resin body can be efficiently reduced by the combined use of solution filtration and melt filtration.

[Filtering process]
(Solution filtration)
The specific method of solution filtration is not particularly limited as long as it is a method of filtering a solution containing a thermoplastic resin (resin (A)) that is a raw material of the thermoplastic resin body.

  The filter used for solution filtration is not particularly limited, and examples thereof include a leaf disk filter, a candle filter, a pack disk filter, and a cylindrical filter. Among these, a leaf disk filter and a candle filter having a high effective filtration area are preferable, and a candle filter is more preferable because space can be saved.

  The filter medium of the filter is not particularly limited. For example, various types of fibers such as polypropylene, cotton, polyester, viscose rayon and glass fiber, or roving yarn wound bodies, filter media made of phenol resin impregnated cellulose, filter media obtained by sintering metal fiber nonwoven fabric, metal powder Any filter medium such as a sintered filter medium, a filter medium in which a plurality of wire meshes are laminated, or a so-called hybrid filter medium in which these filter media are combined can be used. Among these, a filter medium obtained by sintering a non-woven fabric of metal fibers is preferable because of excellent durability and pressure resistance.

  The filtration accuracy of the solution filtration is not particularly limited as long as at least a part of the gel contained in the resin (A) can be removed. For example, it is 15 μm or less, and it is assumed that the obtained resin body is used as an optical member. It is preferably 5 μm or less because optical defects can be further reduced. The lower limit of the filtration accuracy is not particularly limited, but is 0.2 μm, for example.

  In solution filtration, the pressure loss A (pressure loss A of solution filtration) generated in the filter used for the filtration is preferably 3 MPa or less. Although the minimum of the pressure loss A is not specifically limited, For example, it is 0.1 Mpa or more. If the pressure loss A is too small, the flow path tends to be biased when the solution passes through the filter, and the gel removal may become uneven. On the other hand, if the pressure loss A is excessive, the gel may be deformed when the solution passes through the filter, and the gel removal rate may decrease.

  The pressure loss A can be adjusted by the shape and filtration area of the filter, the filtration speed, the type of solvent used, the temperature of the solution, the concentration of the resin contained in the solution, and the like. The pressure loss A can be obtained from the difference between the inlet pressure and the outlet pressure of the filter used for solution filtration.

  Although the temperature of the solution at the time of solution filtration will not be specifically limited if it is less than the boiling point of the solvent under filtration pressure, For example, when resin (A) is an acrylic resin, it is room temperature-about 150 degreeC.

  In solution filtration, a solution containing the resin (A) as a raw material of the thermoplastic resin body is filtered. However, the solution may contain only the resin (A) as the thermoplastic resin, or other than the resin (A). Other resins may be included.

  Stated another way, in the method for producing a thermoplastic resin body of the present invention, when the thermoplastic resin body is composed of a resin composition containing a plurality of thermoplastic resins, at least one thermoplastic in the composition. What is necessary is just to perform solution filtration with respect to resin (preferably the thermoplastic resin which is a main component of a composition). As an example, when an acrylic film mainly composed of an acrylic resin is produced as a thermoplastic resin body, solution filtration may be performed on the acrylic resin. Of course, solution filtration may be performed on the solution of the composition, but it may be difficult to select a solvent that dissolves all the thermoplastic resins contained in the composition. In addition, when selection of a solvent is difficult, it is also possible to obtain a resin composition by performing solution filtration separately with respect to each thermoplastic resin, and mixing the resin after filtration.

  When solution filtration is performed on the at least one thermoplastic resin, the resin and another thermoplastic resin are mixed at any time after the solution filtration to form a resin composition, and the thermoplastic resin is formed from the composition. The body can be manufactured. The mixing of the resin that has been subjected to solution filtration and the other resin may be before or after the melt filtration. However, since the gel may be generated with the heating during the mixing, the resin is melted. It is preferably before filtration. That is, in the method for producing a thermoplastic resin body of the present invention, when the thermoplastic resin body is composed of a resin composition containing a plurality of thermoplastic resins, at least one thermoplastic resin constituting the composition is subjected to solution filtration. Then, a thermoplastic resin after solution filtration and another thermoplastic resin different from the resin are mixed to obtain a resin composition containing the resin after solution filtration, and the composition is subjected to melt filtration. May be.

  The “main component” in the resin composition refers to a resin having the maximum content in the composition, and typically refers to a resin having a content in the composition of 50% by weight or more.

  In the method for producing a thermoplastic resin body of the present invention, the resin (A) may be formed by solution polymerization, and solution filtration may be performed on the polymerization solution containing the resin (A) formed by the polymerization. In this case, efficient solution filtration can be performed, and the production of the thermoplastic resin body becomes more efficient.

(Melting filtration)
The specific method of melt filtration is not particularly limited as long as it is a method of filtering the resin (A) after solution filtration in a state where the resin is hot melted.

  The filter used for melt filtration is not particularly limited, and for example, a polymer filter can be used. As the polymer filter, for example, the above-described various filters can be used. However, even when the effective filtration area is large and the viscosity of the molten resin that is a filtration target is high, the pressure loss generated during filtration can be reduced. Is preferred.

  The filtration accuracy of the melt filtration is not particularly limited, and is, for example, 40 μm or less. If it is assumed that the obtained resin body is used as an optical member, the optical defect can be further reduced, so that it is preferably 15 μm or less. The lower limit of the filtration accuracy is not particularly limited, but is 1 μm, for example.

  1-15 MPa is preferable and, as for the pressure loss B (pressure loss B of melt filtration) which arises in the filter used for the said filtration in the case of melt filtration, 3-10 MPa is more preferable. If the pressure loss B is excessively small, the resin in the heat-melted state tends to be biased in the flow path when passing through the filter, and it may be difficult to remove the uniform gel. On the other hand, when the pressure loss B is excessive, the filter is easily damaged.

  The pressure loss B can be adjusted by the filtration temperature (the temperature of the molten resin or the temperature of the filter), the filtration speed, the filtration area of the filter, and the like. The pressure loss B can be obtained from the difference between the inlet pressure and the outlet pressure of the filter used for melt filtration.

  Although the temperature of the molten resin at the time of melt filtration is not specifically limited, For example, when resin (A) is an acrylic resin, it is about 220-300 degreeC.

  The difference (BA) between the pressure loss A for solution filtration and the pressure loss B for melt filtration is preferably 3 MPa or more. In this case, since the filtration speed at the time of melt filtration can be improved while reliably removing the gel in the solution filtration, the influence of the heat history on the resin (A) is reduced.

  Melt filtration can be carried out independently of the other steps in the production method of the present invention, but the resin (A) or the resin composition containing the resin (A) is melt-molded with a thermoplastic resin body. It is preferable to carry out immediately before the molding step. Even after solution filtration is performed, there is a possibility that gel may be formed in any process that involves heating until the final thermoplastic resin body is formed, or foreign substances may be mixed in the molding process. By carrying out melt filtration immediately before the step, the amount of gel contained in the obtained resin body can be more reliably reduced.

  The method for carrying out the melt filtration immediately before the molding step is not particularly limited. For example, when a thermoplastic resin body is obtained by melt extrusion molding, the resin (A) that has passed through the polymer filter using an extruder equipped with a polymer filter or What is necessary is just to extrude the resin composition containing resin (A) in the state which these heat-melted.

  When the thermoplastic resin body is made of a resin composition containing a plurality of thermoplastic resins, as described above, solution filtration may be performed on at least one thermoplastic resin in the composition. After performing melt filtration on the at least one thermoplastic resin after filtration, the resin after melt filtration and another thermoplastic resin may be mixed to form a resin composition, or after solution filtration. You may melt-filter with respect to the resin composition (resin composition containing the thermoplastic resin after solution filtration) obtained by mixing the said at least 1 type of thermoplastic resin and another thermoplastic resin. In consideration of the possibility that a gel may be generated with heating when the thermoplastic resin is mixed, it is preferable to perform melt filtration on the resin composition.

  In the method for producing a thermoplastic resin body of the present invention, the number of times of both filtrations is not particularly limited as long as at least one melt filtration is performed after solution filtration.

[Molding process]
In the method for producing a thermoplastic resin body of the present invention, a resin composition containing the resin (A) after the filtration step or the resin (A) after the filtration step is melt-molded to obtain a thermoplastic resin body. The melt molding method and the apparatus used for melt molding are not particularly limited, and known methods and apparatuses can be selected according to the type of thermoplastic resin to be produced.

  When manufacturing the pellet which consists of resin composition containing resin (A) or resin (A) as a thermoplastic resin body, the melt extruder and pelletizer provided with the die | dye which has a nozzle hole can be used, for example. When manufacturing the film (thermoplastic resin film) which consists of a resin composition containing resin (A) or resin (A) as a thermoplastic resin body, for example, use a melt extruder and a cooling roll equipped with a T-die. Can do.

  By the way, by re-molding the produced pellet, a thermoplastic resin body (for example, a thermoplastic resin film) having a shape other than the pellet can be produced from the pellet. At this time, when the process of melt-molding the pellets again is considered as the molding process, the method for producing the thermoplastic resin body of the present invention includes the resin (A) or the resin composition containing the resin (A) in addition to the filtration process and the molding process. A step of pelletizing the product (pelletizing step) may be further included.

  As described above, in the method for producing a thermoplastic resin body of the present invention, the number of times of performing both filtrations is not particularly limited as long as at least one melt filtration is performed after solution filtration. That is, when the production method of the present invention includes a pelletizing step and a molding step for melt-molding the pellets formed in the pelletizing step, both solution filtration and melt filtration are performed at a stage before the pelletizing step. Alternatively, only solution filtration may be performed. Even if the pellets are obtained only when solution filtration is performed, if the melt filtration is performed before the final thermoplastic resin body is obtained, foreign substances such as gels contained in the obtained resin body can be obtained. The effect of the present invention that the amount is reduced is obtained.

  The method for producing a thermoplastic resin body of the present invention may include any step other than the steps described above.

According to the production method of the present invention, for example, the following thermoplastic resin body can be produced. Particles contained in the solution measured by a particle counter in accordance with JIS B9925 when the resin body is dissolved in a solvent (for example, chloroform) that has been filtered and purified with a filtration accuracy of 0.1 μm to obtain a solution having a concentration of 1% by weight. A thermoplastic resin body in which the number of particles having a diameter of 5 to 10 μm is 200 or less per gram of resin body. Alternatively, when a film having an area of 1 m ² and a thickness of 90 μm is used, a thermoplastic resin body having 10 or less transparent defects having a size of 20 μm or more contained in the film, which is visually counted under an optical microscope.

[Thermoplastic resin (A)]
The kind of resin (A) is not specifically limited, For example, it is an acrylic resin. When the resin (A) is an acrylic resin, a thermoplastic resin body excellent in transparency, and more specifically, a thermoplastic resin film excellent in transparency can be produced. Here, the acrylic resin is a resin having a (meth) acrylic acid ester unit and / or a (meth) acrylic acid unit as a structural unit. The total of the proportions of (meth) acrylic acid ester units and (meth) acrylic acid units in all structural units of the acrylic resin is usually 50% or more, preferably 60% or more, more preferably 70% or more. .

  (Meth) acrylic acid ester units are, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, t- (meth) acrylic acid t- Butyl, n-hexyl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, chloromethyl (meth) acrylate, 2-chloroethyl (meth) acrylate, 2-hydroxy (meth) acrylate Ethyl, 3-hydroxypropyl (meth) acrylate, 2,3,4,5,6-pentahydroxyhexyl (meth) acrylate, 2,3,4,5-tetrahydroxypentyl (meth) acrylate, 2- Structural units derived from monomers such as (hydroxymethyl) methyl acrylate and 2- (hydroxyethyl) methyl acrylate A. Resin (A) which is an acrylic resin may have two or more of these structural units as a (meth) acrylic acid ester unit. Moreover, it is preferable that resin (A) which is an acrylic resin has a (meth) acrylic acid methyl unit as a (meth) acrylic acid ester unit.

  The weight average molecular weight of the resin (A) is, for example, in the range of 1,000 to 300,000, preferably in the range of 5,000 to 250,000, more preferably in the range of 10,000 to 200,000, and still more preferably in the range of 50,000 to 200,000.

  Hereinafter, the resin (A) which is an acrylic resin will be described.

  The resin (A) preferably has a ring structure in the main chain. In this case, the glass transition temperature (Tg) of the resin (A) is improved. The Tg of the resin (A) is, for example, 110 ° C. or more depending on the inclusion of the ring structure, and is 120 ° C. or more, further 130 ° C. or more depending on the type of the ring structure and the content of the ring structure in the resin (A). By using the high Tg resin (A) as a raw material in this way, a thermoplastic resin body (for example, a thermoplastic resin film) having excellent heat resistance can be obtained. For example, the resin body is used in an image display device. It is suitable for use as an optical member because it can be easily placed near a heat generating part such as a light source. In addition, Tg in this specification shall be the value calculated | required by the midpoint method using the differential scanning calorimeter (DSC) based on the prescription | regulation of ASTM-D-3418.

  By the way, when Tg of resin (A) becomes high by a ring structure, while the said effect is acquired, it is necessary to make high the temperature which melt-filters the resin composition containing resin (A) or resin (A). For this reason, in the conventional production method in which only melt filtration is performed, when a thermoplastic resin having a ring structure in the main chain is used for the purpose of producing a thermoplastic resin body having excellent heat resistance, gel removal is insufficient. Tended to be. On the other hand, in the method for producing a thermoplastic resin body of the present invention, since the filtration temperature is a solution filtration that is not affected by the Tg of the resin (A), the resin (A) has a ring structure in the main chain. In this case, the gel can be removed efficiently. That is, when the resin (A) has a ring structure in the main chain, the effect of the present invention becomes more remarkable.

  Although the kind of ring structure is not specifically limited, For example, it is at least 1 sort (s) chosen from glutarimide structure, glutaric anhydride structure, maleic anhydride structure, N-substituted maleimide structure, and lactone ring structure.

  Since the Tg of the resin (A) is further improved, the ring structure is preferably at least one selected from a glutarimide structure, a glutaric anhydride structure, and a lactone ring structure. Moreover, since the thermoplastic resin body excellent in an optical characteristic is obtained, it is more preferable that a ring structure is a lactone ring structure. That is, the resin (A) is more preferably an acrylic resin having a lactone ring structure in the main chain.

  In addition, in the manufacturing process of the resin (A), when a ring structure is formed in the skeleton by a cyclization condensation reaction after the main chain skeleton is first formed, gel due to cross-linking between the resins is likely to occur. For this reason, in this case, the effect of the present invention becomes more remarkable. Resin (A) formed by such a manufacturing process includes, for example, an acrylic resin having a lactone ring structure in the main chain.

  The following formula (1) shows a glutarimide structure and a glutaric anhydride structure.

In the above formula (1), R ¹ and R ² are each independently a hydrogen atom or a methyl group, and X ¹ is an oxygen atom or a nitrogen atom. When X ¹ is an oxygen atom, R ³ does not exist, and when X ¹ is a nitrogen atom, R ³ is a hydrogen atom, a linear alkyl group having 1 to 6 carbon atoms, a cyclopentyl group, a cyclohexyl group, or a phenyl group. .

When X ¹ is a nitrogen atom, the ring structure represented by the formula (1) is a glutarimide structure. When X ¹ is an oxygen atom, the ring structure represented by the formula (1) is a glutaric anhydride structure.

  The following formula (2) shows an N-substituted maleimide structure and a maleic anhydride structure.

In the above formula (2), R ⁴ and R ⁵ are each independently a hydrogen atom or a methyl group, and X ² is an oxygen atom or a nitrogen atom. When X ² is an oxygen atom, R ⁶ does not exist, and when X ² is a nitrogen atom, R ⁶ is a hydrogen atom, a linear alkyl group having 1 to 6 carbon atoms, a cyclopentyl group, a cyclohexyl group, or a phenyl group. .

When X ² is a nitrogen atom, the ring structure represented by the formula (2) is an N-substituted maleimide structure. When X ² is an oxygen atom, the ring structure represented by the formula (2) is a maleic anhydride structure.

  The lactone ring structure that the resin (A) may have in the main chain is not particularly limited, and may be, for example, a 4- to 8-membered ring. However, the 5-membered ring is excellent in stability as a ring structure. Alternatively, a 6-membered ring is preferable, and a 6-membered ring is more preferable. The 6-membered lactone ring structure is, for example, the structure disclosed in Japanese Patent Application Laid-Open No. 2004-168882, but the precursor (the lactone ring structure is converted into the main chain by cyclization condensation reaction of the precursor). The polymerization yield of the resin (A) is high), the resin (A) having a high lactone ring content can be obtained by the cyclocondensation reaction of the precursor, and the methyl methacrylate unit is a structural unit. A structure represented by the following formula (3) is preferable because the polymer can be used as a precursor.

In the above formula (3), R ⁷ , R ⁸ and R ⁹ are each independently a hydrogen atom or an organic residue having 1 to 20 carbon atoms. The organic residue may contain an oxygen atom.

  The organic residue in Formula (3) is, for example, an alkyl group having 1 to 20 carbon atoms such as a methyl group, an ethyl group, or a propyl group; and an alkyl group having 1 to 20 carbon atoms such as an ethenyl group or a propenyl group. An unsaturated aliphatic hydrocarbon group; an aromatic hydrocarbon group having 1 to 20 carbon atoms such as a phenyl group and a naphthyl group; in the alkyl group, the unsaturated aliphatic hydrocarbon group, and the aromatic hydrocarbon group , A group in which one or more of hydrogen atoms are substituted with at least one group selected from a hydroxyl group, a carboxyl group, an ether group and an ester group.

The lactone ring structure can be formed by subjecting a precursor having a hydroxyl group and an ester group in the molecular chain to a dealcoholization cyclocondensation reaction. The lactone ring represented by the formula (3) is formed, for example, by forming a copolymer of methyl methacrylate (MMA) and 2- (hydroxymethyl) methyl acrylate (MHMA), and then adjoining MMA in the copolymer. It can be formed by dealcoholization cyclocondensation of units and MHMA units. At this time, R ⁷ is H, and R ⁸ and R ⁹ are CH ₃ .

  When the resin (A) has a ring structure in the main chain, the content of the ring structure in the resin (A) is not particularly limited, but is usually 5 to 90% by weight, and preferably 20 to 90% by weight. The content is more preferably 30 to 90% by weight, 35 to 90% by weight, 40 to 80% by weight, and 45 to 75% by weight. When the content is too low, it is difficult to obtain an effect based on the resin (A) having a ring structure in the main chain. On the other hand, when the said content rate becomes excessive, the moldability and handling property of the resin composition containing resin (A) and resin (A) will fall.

  When the resin (A) has a lactone ring structure, the content of the lactone ring structure in the resin (A) can be determined by the dynamic TG method as follows. First, a dynamic TG measurement is performed on the resin (A) having a lactone ring structure, a weight reduction rate between 150 ° C. and 300 ° C. is measured, and the obtained value is an actually measured weight reduction rate (X). And 150 ° C. is a temperature at which the hydroxyl group and ester group remaining in the resin (A) start a cyclization condensation reaction, and 300 ° C. is a temperature at which thermal decomposition of the resin (A) starts. Separately, assuming that all the hydroxyl groups contained in the precursor polymer have undergone a dealcoholization reaction to form a lactone ring, the rate of weight loss due to the reaction (ie, dealcoholization of the precursor) The weight reduction rate (assuming that the condensation reaction rate was 100%) was calculated and used as the theoretical weight reduction rate (Y). Specifically, the theoretical weight reduction rate (Y) can be determined from the content of the structural unit having a hydroxyl group involved in the dealcoholization reaction in the precursor. The composition of the precursor can be derived from the composition of the resin (A) as necessary. Next, the dealcoholization reaction rate of the resin (A) is determined by the formula [1- (actually measured weight reduction rate (X) / theoretical weight reduction rate (Y))] × 100 (%). In the resin (A), it is considered that a lactone ring structure is formed for the determined dealcoholization reaction rate. Therefore, the lactone ring structure in the resin (A) is obtained by multiplying the content of the structural unit having a hydroxyl group involved in the dealcoholization reaction in the precursor by the determined dealcoholization reaction rate and converting it to the weight of the lactone ring structure. The content of can be determined.

  As an example, the dealcoholization reaction rate of the resin (A) produced in Example 1 described later is obtained. The molecular weight of methanol produced by the dealcoholization reaction is 32, and the content of the MHMA unit, which is a constituent unit having a hydroxyl group involved in the dealcoholization reaction, in the precursor (copolymer of MHMA and MMA) is 20% by weight. Since the molecular weight of the MHMA unit in terms of monomer is 116, the theoretical weight reduction rate (Y) of the resin (A) is (32/116) × 20 = 5.52% by weight. On the other hand, since the actual weight reduction rate (X) of the resin (A) was 0.15% by weight, the dealcoholization reaction rate was 97.3% (= (1−0.15 / 5.52) × 100 (%)).

  Next, the content rate of the lactone ring structure in the resin (A) is determined. Since the MHMA unit content in the precursor is 20% by weight, the molecular weight of the MHMA unit in terms of monomer is 116, the dealcoholization reaction rate is 97.3%, and the formula weight of the lactone ring structure is 170. The content of the lactone ring structure in (A) is 28.5% (= 20 × 0.973 × 170/116).

  The resin (A) contains various analysis methods such as infrared spectroscopy, near-infrared spectroscopy, Raman spectroscopy, nuclear magnetic resonance, pyrolysis gas chromatography, or mass spectrometry as the content of the ring structure in the resin (A). You may obtain | require by applying suitably according to the kind of ring structure.

  Resin (A) may have structural units other than the (meth) acrylic acid ester unit and the (meth) acrylic acid unit. Such structural units include, for example, styrene, vinyl toluene, α-methyl styrene, acrylonitrile, methyl vinyl ketone, ethylene, propylene, vinyl acetate, methallyl alcohol, allyl alcohol, 2-hydroxymethyl-1-butene, α- 2- (hydroxyalkyl) acrylic acid ester such as hydroxymethylstyrene, α-hydroxyethylstyrene, methyl 2- (hydroxyethyl) acrylate, 2- (hydroxyalkyl) acrylic acid such as 2- (hydroxyethyl) acrylic acid, A structural unit derived from a monomer such as The resin (A) may have two or more of these structural units.

  The resin (A) may have a structural unit (UVA unit) having ultraviolet absorbing ability. In this case, the ultraviolet absorbing ability of the obtained thermoplastic resin body is improved.

  Resin (A) including resin (A) having a ring structure in the main chain can be formed by a known method. The resin (A) having a lactone ring structure in the main chain can be produced by, for example, the methods described in JP-A-2006-96960, JP-A-2006-171464, and JP-A-2007-63541. A resin (A) having an N-substituted maleimide structure in the main chain, a resin (A) having a glutaric anhydride structure, and a resin (A) having a glutarimide structure are disclosed in, for example, JP-A-2007-31537, International Publication It can be produced by the methods described in the 2007/26659 pamphlet and the international publication 2005/108438 pamphlet. The resin (A) having a maleic anhydride structure in the main chain can be produced, for example, by the method described in JP-A-57-153008.

  As an example, a method for forming a resin (A) having a lactone ring structure in the main chain will be described.

  Resin (A) having a lactone ring structure in the main chain, for example, heats a polymer (precursor) (a) having a hydroxyl group and an ester group in the molecular chain in the presence of any catalyst, and involves dealcoholization. It can be formed by proceeding with a lactone cyclization condensation reaction.

  The polymer (a) can be formed, for example, by polymerization of a monomer group including a monomer represented by the following formula (4).

In the above formula (4), R ¹⁰ and R ¹¹ are each independently a hydrogen atom or a group similar to the organic residue in the formula (3).

  Monomers represented by formula (4) are, for example, methyl 2- (hydroxymethyl) acrylate, ethyl 2- (hydroxymethyl) acrylate, isopropyl 2- (hydroxymethyl) acrylate, 2- (hydroxymethyl) Normal butyl acrylate, t-butyl 2- (hydroxymethyl) acrylate, and the like. Among them, 2- (hydroxymethyl) methyl acrylate and 2- (hydroxymethyl) ethyl acrylate are preferable, and a thermoplastic resin body having high transparency and heat resistance can be obtained. Methyl acid (MHMA) is particularly preferred.

  The monomer group used for forming the polymer (a) may contain two or more monomers represented by the above formula (4).

  The monomer group used for forming the polymer (a) may contain a monomer other than the monomer represented by the above formula (4). This monomer is not particularly limited as long as it can be copolymerized with the monomer represented by the formula (4), and is, for example, (meth) acrylic acid ester.

  Here, the (meth) acrylic acid ester is a monomer other than the monomer represented by the formula (4), for example, methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, acrylic Acrylic acid esters such as t-butyl acid, cyclohexyl acrylate, benzyl acrylate; methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, cyclohexyl methacrylate, Methacrylic acid esters such as benzyl methacrylate; Among these, methyl methacrylate (MMA) is particularly preferable because a thermoplastic resin body having high transparency and heat resistance can be realized.

  The monomer group used for forming the polymer (a) may contain two or more of these (meth) acrylic acid esters.

  The monomer group used for forming the polymer (a) is one or two other monomers such as styrene, vinyl toluene, α-methyl styrene, acrylonitrile, methyl vinyl ketone, ethylene, propylene, and vinyl acetate. More than one species may be included.

(Thermoplastic resin body)
The thermoplastic resin body obtained by the production method of the present invention may be composed of the resin (A) or the resin composition containing the resin (A). When the resin composition is composed of the resin composition, the composition of the composition It is possible to control various physical characteristics such as optical characteristics such as light transmission characteristics, birefringence characteristics, and phase difference characteristics, or heat resistance and ultraviolet absorption characteristics.

  The resin composition may be any material other than the resin (A), for example, a thermoplastic resin other than the resin (A); an ultraviolet absorber, an antioxidant, a lubricant, depending on the properties required for the thermoplastic resin body. An additive such as an antistatic agent, a plasticizer, a fluidizing agent, a colorant, a dye, a flame retardant, and a filler may be included. These materials can be mixed with the resin (A) at an arbitrary point in the production method of the present invention. However, when heating of the resin (A) and the material is necessary during mixing, In order to remove the generated gel as much as possible, mixing before the last melt filtration, typically before the melt filtration performed immediately before forming the thermoplastic resin body by melt molding is preferable.

  When the thermoplastic resin body obtained by the production method of the present invention is composed of a resin composition containing the resin (A), the resin (A) is preferably the main component of the composition. In the production method of the present invention, solution filtration is performed on the resin (A). In this case, the effect of the present invention becomes more remarkable.

  The shape of the thermoplastic resin body obtained by the production method of the present invention is not particularly limited, and is, for example, a pellet or a film (the film includes a so-called sheet).

  When the resin (A) is an acrylic resin, the thermoplastic resin body obtained by the production method of the present invention may be an acrylic film made of a resin composition containing the acrylic resin as a main component.

  The use of the thermoplastic resin body obtained by the production method of the present invention is not particularly limited, but the resin body is suitable as an optical member. This is because the thermoplastic resin body obtained by the production method of the present invention can form an optical member with a small content of foreign matters such as gel and few optical defects.

  When the resin (A) is an acrylic resin, particularly when the resin (A) is an acrylic resin having a ring structure in the main chain, the thermoplastic resin body obtained by the production method of the present invention has transparency and heat resistance. It is excellent and more suitable as an optical member.

  The shape of the optical member is not particularly limited, and is, for example, a film (optical film). The specific use of the optical film is not particularly limited. For example, a birefringent film, a retardation film, a viewing angle compensation film, a light diffusion film, and a reflection film used in image display devices such as liquid crystal displays, plasma displays, and organic EL displays. Examples thereof include a film, an antireflection film, an antiglare film, a brightness enhancement film, a pixel part (light emitting part) protective film, a polarizer protective film, and an ultraviolet absorbing film.

The thermoplastic resin body obtained by the production method of the present invention may be the following thermoplastic resin body. Particles contained in the solution measured by a particle counter in accordance with JIS B9925 when the resin body is dissolved in a solvent (for example, chloroform) that has been filtered and purified with a filtration accuracy of 0.1 μm to obtain a solution having a concentration of 1% by weight. A thermoplastic resin body in which the number of particles having a diameter of 5 to 10 μm is 200 or less per gram of resin body. Alternatively, when a film having an area of 1 m ² and a thickness of 90 μm is used, a thermoplastic resin body having 10 or less transparent defects having a size of 20 μm or more contained in the film, which is visually counted under an optical microscope. These thermoplastic resin bodies are suitable for optical members (optical films).

  The thermoplastic resin body obtained by the production method of the present invention exhibits the following characteristics depending on the type of the resin (A) constituting the resin body or the composition of the resin composition containing the resin (A).

  Regarding the glass transition temperature (Tg), the value is, for example, 110 ° C. or higher, and can be 120 ° C. or higher, or 130 ° C. or higher. Such a high Tg can be realized by using, as the resin (A), an acrylic resin having a ring structure (preferably a lactone ring structure) in the main chain.

  Regarding the visible light transmittance, the transmittance with respect to light having a wavelength of 500 nm when a film having a thickness of 100 μm is, for example, 80% or more, and can be 90% or more. The visible light transmittance can be determined according to JIS K7361. Such a high visible light transmittance can be realized by using an acrylic resin as the resin (A).

  Hereinafter, the present invention will be described in more detail with reference to examples. The present invention is not limited to the examples shown below.

  Initially, the evaluation method of the thermoplastic resin body (pellet and film) produced in a present Example is shown.

[Glass-transition temperature]
The Tg of the produced pellet (Tg of the resin constituting the produced pellet) was determined according to ASTM-D-3418. Specifically, a differential scanning calorimeter (manufactured by Rigaku, DSC-8230) was used, and a temperature of about 10 mg of the sample was raised from room temperature to 200 ° C. under a nitrogen gas flow (50 ml / min) (temperature increase rate 10 ° C./min). ) Was evaluated by the midpoint method from the DSC curve obtained.

[Lactone ring content]
The lactone ring content of the prepared pellet (the lactone ring content of the resin constituting the prepared pellet) was evaluated by the calculation method described above. The measured weight loss rate (X), which is a parameter used in the method, was determined by dynamic TG measurement as follows.

The prepared pellets or the polymerization solution before the pellets were dissolved in tetrahydrofuran (THF) (or after dilution with THF), and then the resin was precipitated using excess hexane or methanol. Next, the precipitate is vacuum dried (pressure 1.33 hPa, 80 ° C., 3 hours or more) to remove volatile components, and the obtained white solid resin is subjected to dynamic TG measurement under the following measurement conditions. The actual weight reduction rate (X) was obtained.
Measuring device: Rigaku, Thermo Plus 2 TG-8120 Dynamic TG
Sample weight: 5-10mg
Temperature increase rate: 10 ° C./min Atmosphere: under nitrogen flow (200 ml / min) Measurement method: step-like isothermal control method (controlled at 60 to 500 ° C. with a weight reduction rate value of 0.005% / sec or less)

[Melt flow rate (MFR)]
The MFR of the produced pellets was determined according to JIS K7120, with the test temperature set at 240 ° C. and the load set at 10 kg.

[Number of foreign objects]
The number of foreign substances contained in the prepared pellets (number per 1 g of pellets) was evaluated based on the number of particles having a particle size in the range of 5 to 10 μm measured by a particle counter. Particle counter (manufactured by PAMAS, light scattering type automatic particle counter for liquid, model: SVSS-C, sensor specification: HCB-LD-50 / 50, JIS B9925 which defines the specification of light scattering type automatic particle counter for liquid The measurement was performed on a solution having a concentration of 1% by weight formed by dissolving pellets in chloroform purified by filtration with a filtration accuracy of 0.1 μm. The pellet was dissolved in chloroform after the particle counter confirmed that the number of particles contained in the chloroform after purification by filtration was zero.

[Number of transparent defects]
The number of transparent defects (number per area 1 m ² , thickness 90 μm) present in the produced film was evaluated as follows.

A film having a thickness of 90 μm was produced, and the film after 12 hours had been produced was cut into A4 size. The cut film was visually counted under an optical microscope to count the number of transparent defects having a size of 20 μm or more. Asked. In addition, the number of cut out films was five, and after obtaining the number of transparent defects for each film, the average of the obtained numbers was converted to a value per 1 m ² area.

  The transparent defect is considered to be caused by the remaining gel and becomes an optical defect because its optical characteristics are different from the surroundings. Transparent defects are observed under a microscope as shadows in transmitted light and bright spots in reflected light. Here, the transparent defect having a size of 20 μm or more refers to a defect having a maximum length of 20 μm or more among the observed transparent defects. In addition, even if the size of the core portion is less than 20 μm, the lens effect may be caused by the strain applied to the film, and optical distortion may be observed in the vicinity of the core portion. In this case, a determination was made on the overall size of the observed distortion. Note that the shape and size of the target transparent defect can be easily reconfirmed by, for example, a laser microscope.

Example 1
In a reactor having an internal volume of 1 m ³ equipped with a stirrer, a temperature sensor, a cooling pipe and a nitrogen introducing pipe, 136 kg of methyl methacrylate (MMA), 34 kg of methyl 2- (hydroxymethyl) methyl acrylate (MHMA), and polymerization 166 kg of toluene was charged as a solvent, and the temperature was raised to 105 ° C. while introducing nitrogen into the solvent. When refluxing with a rise in temperature started, 187 g of t-amyl peroxyisononanoate (manufactured by Arkema Yoshitomi, trade name: Luperox 570) was added as a polymerization initiator, and the above t-amyl was added to 3.6 kg of toluene. While a solution in which 374 g of peroxyisononanoate was dissolved was added dropwise over 2 hours, solution polymerization was allowed to proceed under reflux at about 105 to 110 ° C., followed by further aging for 4 hours.

  Next, 170 g of stearyl phosphate / distearyl phosphate mixture (Phoslex A-18, manufactured by Sakai Chemical Co., Ltd.) was added to the resulting polymerization solution as a catalyst for the cyclization condensation reaction (cyclization catalyst). The cyclization condensation reaction was allowed to proceed for 5 hours under reflux at 110 ° C.

  All the above materials were filtered through a filter having a filtration accuracy of 0.2 μm and then introduced into the reactor.

  Next, the polymer solution thus obtained was subjected to solution filtration. For the solution filtration, a candle filter made of SUS316L sintered fiber and having a filtration accuracy of 5 μm was used, and the temperature of the polymerization solution subjected to solution filtration was set to 85 ° C. The pressure loss A of the solution filtration was 0.5 MPa, and the viscosity of the polymerization solution at 85 ° C. (that is, the viscosity of the polymerization solution at the time of solution filtration) obtained separately was 25 Pa · sec.

  Next, the polymer solution after solution filtration was introduced into a vented twin-screw extruder equipped with a leaf disk filter at the tip, and the solvent and volatile components were devolatilized. During devolatilization, the cyclization catalyst (stearyl phosphate / distearyl phosphate mixture) and equimolar zinc octylate were filtered through a filter having a filtration accuracy of 0.2 μm, and then the cyclization catalyst was deactivated. It was introduced into the extruder as an agent.

  After completion of devolatilization, the resin in the molten state remaining in the extruder is melt-filtered by passing through a leaf disc filter disposed at the tip of the extruder, and then pelletized by a pelletizer to obtain transparent resin pellets ( P-1A) was obtained. As the leaf disk filter, a filter made of SUS316L sintered fiber and having a filtration accuracy of 5 μm was used. The temperature of melt filtration (the temperature in the extruder and the temperature of the leaf disk filter) is 280 ° C., and the viscosity of the resin at 280 ° C. (that is, the viscosity of the resin at the time of melt filtration) obtained separately is 700 Pa · sec. there were. The pressure loss B of melt filtration was 5 MPa.

  The resin pellets were taken out in an environment of class 10,000 (US federal standard, FED-STD-209D) and packed in an aluminum bag manufactured in an environment of class 10,000 or less.

When the lactone ring content, MFR, Tg and the number of foreign substances of the pellet (P-1A) thus obtained were evaluated, 28.5% (actual weight loss rate (X) measured by dynamic TG was 0). .15 wt%), 11.9 g / min, 128 ° C. and 40 pcs / g. Moreover, the weight average molecular weight of resin which comprises the pellet (P-1A) evaluated by gel permeation chromatography (GPC: GPC system by Tosoh, chloroform solvent, polystyrene conversion) was 125000. The method for measuring the weight average molecular weight is the same in the following examples, reference examples, and comparative examples.

  Next, the pellet (P-1A) was charged into a single screw extruder with a vent (φ = 65 mm, L / D = 32, barrier flight type screw), and melt-kneaded. In addition, before charging a pellet (P-1A) to an extruder, the dehumidified air heated at 60 degreeC was sprayed on the pellet in the hopper part, and the said pellet was dehumidified. When melt-kneading the pellets, nitrogen gas was introduced into the extruder from the hopper, and suction was performed from the vent port so that the pressure in the extruder was 13 hPa (10 mmHg).

  Next, the melt-kneaded resin is melt-filtered by passing through a leaf disk filter disposed at the tip of the extruder, and then melt-formed by a T-die to obtain a film (F-1A) having a thickness of 90 μm. It was. As the leaf disk filter, a filter made of SUS316L sintered fiber and having a filtration accuracy of 5 μm was used. The temperature of melt filtration and melt molding (the temperature in the extruder, the temperature of the leaf disk filter, the temperature of the T die) was 275 ° C., and the amount of resin extruded onto the T die was 33 kg / hour. The pressure loss B of melt filtration was 4 MPa.

  When the number of transparent defects in the obtained film (F-1A) was evaluated, it was 3.

( Reference Example 1 )
A transparent resin pellet (P-2A) was obtained in the same manner as in Example 1 except that melt filtration with a leaf disk filter was not performed when producing the resin pellet. The pressure loss A of solution filtration was 0.5 MPa.

  When the lactone ring content, MFR, Tg, and the number of foreign substances of the pellet (P-2A) thus obtained were evaluated, they were 28.4% (actual weight loss rate (X) measured by dynamic TG was 0). .17% by weight), 10.5 g / min, 129 ° C. and 240 pcs / g. Moreover, the weight average molecular weight of resin which comprises a pellet (P-2A) was 125000.

  Next, a 90 μm-thick film (F-2A) was obtained in the same manner as in Example 1 except that the prepared pellet (P-2A) was used instead of the pellet (P-1A). When the number of transparent defects in the obtained film (F-2A) was evaluated, it was 10. In addition, the pressure loss B of the melt filtration at the time of film preparation was 4 MPa.

(Comparative Example 1)
A transparent resin pellet (P-1B) was obtained in the same manner as in Example 1 except that when the resin pellet was produced, solution filtration using a candle filter was not performed. The pressure loss B of melt filtration was 5.5 MPa.

  When the lactone ring content, MFR, Tg, and the number of foreign substances of the pellets (P-1B) thus obtained were evaluated, 28.5% (actual weight loss rate (X) measured by dynamic TG was 0). .15 wt%), 12.0 g / min, 128 ° C. and 350 pcs / g. Moreover, the weight average molecular weight of resin which comprises a pellet (P-1A) was 124000.

  Next, a film (F-1B) having a thickness of 90 μm was obtained in the same manner as in Example 1 except that the prepared pellet (P-1B) was used instead of the pellet (P-1A). When the number of transparent defects in the obtained film (F-1B) was evaluated, it was 50. In addition, the pressure loss B of the melt filtration at the time of film preparation was 3.4 MPa.

(Comparative Example 2)
Transparent resin pellets (P-2B) were obtained in the same manner as in Example 1, except that both solution filtration using a candle filter and melt filtration using a leaf disk filter were not performed when the resin pellets were produced. It was.

  When the lactone ring content, MFR, Tg, and the number of foreign substances of the pellet (P-2B) thus obtained were evaluated, 28.5% (actual weight loss rate (X) measured by dynamic TG was 0), respectively. .16 wt%), 11.0 g / min, 129 ° C. and 850 pcs / g. Moreover, the weight average molecular weight of resin which comprises a pellet (P-2B) was 126000.

  Next, a 90 μm-thick film (F-2B) was obtained in the same manner as in Example 1 except that the prepared pellet (P-2B) was used instead of the pellet (P-1A). When the number of transparent defects in the obtained film (F-2B) was evaluated, it was 120. In addition, the pressure loss B of the melt filtration at the time of film preparation was 4.2 MPa.

(Example 2 )
The pellet (P-1B) produced in Comparative Example 1 was dissolved in methyl isobutyl ketone to obtain a solution having a concentration of 50% by weight, and the produced solution was subjected to solution filtration using a candle filter. The solution filtration was performed in the same manner as the solution filtration at the time of preparing the pellet (P-1A) in Example 1, and the temperature of the solution to be filtered was 90 ° C. The pressure loss A of solution filtration was 0.7 MPa, and the viscosity of the solution at 90 ° C. obtained separately was 22 Pa · sec.

  Next, the solution after solution filtration was devolatilized, melt filtered and pelletized in the same manner as in Example 1 to obtain transparent resin pellets (P-3A). The pressure loss B of melt filtration was 4.5 MPa.

  When the lactone ring content, MFR, Tg, and the number of foreign substances of the pellet (P-3A) thus obtained were evaluated, 28.5% (actual weight loss rate (X) measured by dynamic TG was 0), respectively. .16 wt%), 12.7 g / min, 128 ° C. and 45 pcs / g. Moreover, the weight average molecular weight of resin which comprises a pellet (P-3A) was 122000.

  Next, a film (F-3A) having a thickness of 90 μm was obtained in the same manner as in Example 1 except that the prepared pellet (P-3A) was used instead of the pellet (P-1A). When the number of transparent defects in the obtained film (F-3A) was evaluated, it was 2. In addition, the pressure loss B of the melt filtration at the time of film preparation was 4.5 MPa.

(Example 3 )
The pellet (P-2A) produced in Reference Example 1 was introduced into a single-screw extruder with a vent (φ = 50 mm, L / D = 36) equipped with a leaf disk filter at the tip, and melt filtration was performed using the filter. And then pelletized again with a pelletizer to obtain transparent resin pellets (P-4A). As the leaf disk filter, a filter made of SUS316L sintered fiber and having a filtration accuracy of 5 μm was used. The melt filtration temperature (the temperature in the extruder and the temperature of the leaf disk filter) was 285 ° C. The pressure loss B of melt filtration was 10 MPa, and the viscosity obtained when the pellet (P-2A) was melted at 285 ° C. was 650 Pa · sec.

  When the lactone ring content, MFR, Tg, and the number of foreign substances of the pellet (P-4A) thus obtained were evaluated, they were 28.4% (actual weight loss rate (X) measured by dynamic TG was 0). .17 wt%), 14.0 g / min, 128 ° C. and 87 pcs / g. Moreover, the weight average molecular weight of resin which comprises a pellet (P-4A) was 116000.

  Next, a film (F-4A) having a thickness of 90 μm was obtained in the same manner as in Example 1 except that the prepared pellet (P-4A) was used instead of the pellet (P-1A). When the number of transparent defects in the obtained film (F-4A) was evaluated, it was 3. In addition, the pressure loss B of the melt filtration at the time of film preparation was 4.2 MPa.

Implementation status of solution filtration and melt filtration in Examples 1 to 3, Reference Example 1 and Comparative Examples 1 to 2, and the number of foreign matters in the pellets and the number of transparent defects in the film produced in each Example, Reference Example, and Comparative Example Are summarized in Table 1 below.

(About pellets)
As shown in Table 1, compared to Comparative Example 1 in which only melt filtration was performed and Comparative Example 2 in which filtration was not performed, Reference Example 1 in which solution filtration was performed and Example 1 in which solution filtration and melt filtration were performed In ~ 3 , the number of foreign substances contained in the pellet could be reduced. In particular, in Examples 1 to 3 in which solution filtration and melt filtration were performed, the number of foreign matters could be significantly reduced as compared with the comparative example, for example, the number of foreign matters was 100 pieces / g or less.

In addition, in the pellet produced in Reference Example 1 , although the number of foreign matters contained in the pellet itself was relatively large, it was significantly more transparent than Comparative Examples 1 and 2 by forming the pellet after melting and filtering the pellet. The number of dent defects could be reduced. Although the pellet produced in Reference Example 1 is a pellet obtained by performing only solution filtration as a filtration step, the gel contained in the resin body obtained by the molding by performing melt molding combined with melt filtration, etc. It was found that the resin pellets can reduce the amount of foreign matter.

(About film)
As shown in Table 1, compared to Comparative Examples 1 and 2 in which only melt filtration was performed, in Examples 1 to 3 and Reference Example 1 in which solution filtration and melt filtration were performed, the number of transparent defects in the film was greatly increased. We were able to reduce to. In particular, in Examples 1 to 3 where both solution filtration and melt filtration were performed at the time of pellet production, the number of transparent defects was 5 or less.

In Comparative Example 1, the melt filtration was performed twice considering the state of the polymerization solution, but the solution filtration and the melt filtration were each performed once considering the state of the polymerization solution. In Reference Example 1 , the number of transparent defects could be reduced.

  According to the present invention, it is possible to obtain a thermoplastic resin body that contains a small amount of foreign matter such as gel. This thermoplastic resin body is suitable for use as an optical member, for example.

Claims (14)

A method for producing a thermoplastic resin body, comprising: a filtration step for a thermoplastic resin; and a molding step for melt-molding the resin that has undergone the filtration step or a resin composition containing the resin,
Examples filtration step, have rows and solution filtration the solution is filtered, the resin after the solution is filtered and a melt filtration for filtering in a state in which the resin is thermally melted containing said resin,
A method for producing a thermoplastic resin body, wherein in the molding step, the resin or the resin composition is melt-molded to obtain pellets of the resin or the resin composition . The method for producing a thermoplastic resin body according to claim 1, wherein in the molding step, the obtained pellet is further melt-molded. The method for producing a thermoplastic resin body according to claim 1, wherein in the molding step, the obtained pellets are melt-filtered and further melt-molded. The method for producing a thermoplastic resin body according to claim 1, wherein in the molding step, the obtained pellet is further melt-molded to obtain a film.   The method for producing a thermoplastic resin body according to claim 1, wherein the filtration accuracy of the solution filtration is 5 μm or less.   The method for producing a thermoplastic resin body according to claim 1, wherein the filtration accuracy of the melt filtration is 15 μm or less. The method for producing a thermoplastic resin body according to claim 1, wherein the filter used for the solution filtration is a candle filter. The method for producing a thermoplastic resin body according to claim 1, wherein the filter used for the melt filtration is a leaf disk filter.   The difference (BA) between the pressure loss A generated in the filter used for the filtration during the solution filtration and the pressure loss B generated in the filter used for the filtration during the melt filtration is 3 MPa or more. The method for producing a thermoplastic resin body according to claim 1.   The method for producing a thermoplastic resin body according to claim 1, wherein the thermoplastic resin is an acrylic resin. The method for producing a thermoplastic resin body according to claim 10 , wherein the acrylic resin has a ring structure in the main chain. The method for producing a thermoplastic resin body according to claim 11, wherein the ring structure is at least one selected from a glutarimide structure, a glutaric anhydride structure, a maleic anhydride structure, an N-substituted maleimide structure, and a lactone ring structure. The method for producing a thermoplastic resin body according to claim 11 , wherein the ring structure is a lactone ring structure. Forming the thermoplastic resin by solution polymerization;
The method for producing a thermoplastic resin body according to claim 1, wherein the solution filtration is performed on a polymerization solution containing the resin generated by the polymerization.