JP2008133462A - Heat-resistant acrylic resin, and filtering method and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat-resistant acrylic resin excellent in the external appearance and physical properties. <P>SOLUTION: The filtering method for a heat-resistant acrylic resin according to the present invention comprises using a polymer filter which is provided with a housing, a center pole 9, a leaf disk filter 7 having a filtration precision of 15 μm or less, a holding disk 3 positioned upstream from the leaf disk filter 7, and a cap 1 having a bolt for fixing the holding disk 3 to the center pole 9, wherein the above polymer filter has a seal ring 10 in the clearance between the above center pole 9 and the above holding disk 3. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a melt filtration method for heat-resistant acrylic resins, and more particularly to a melt filtration method for heat-resistant acrylic resins with little foreign matter and deteriorated materials used in optical applications.

  An acrylic resin typified by PMMA has excellent optical performance, and has been adapted to various optical materials as an optical isotropic material having high light transmittance, low birefringence, and low phase difference. However, in recent years, with the progress of flat displays such as liquid crystal display devices, plasma displays, organic EL display devices, infrared sensors, optical waveguides, etc., there has been an increasing demand for reducing foreign substances in optical transparent polymer materials.

  Usually, the resulting acrylic resin contains gels generated during the polymerization process and granulation process, and extraneous foreign matter mixed in from the surrounding environment. In the case of melt plasticizing using an extruder and forming into pellets, sheets or films, rods or fibers, or extruding and kneading with other compatible thermoplastic resins or various additives, etc. Need to be removed.

  As a method for removing the gel and foreign matters in the polymer melt state, for example, a method of filtering using a leaf disk type polymer filter is known.

  However, since acrylic resins have high melt viscosity and low heat resistance, they are particularly susceptible to a great heat history. In addition, in the case of applying a polymer filter having a filtration accuracy of 15 μm or less in which the filtration pressure is increased, the resin temperature must necessarily be raised to lower the melt viscosity, and foaming or resin may be caused by depolymerization or main chain cutting. Deterioration occurs.

  For this reason, it was difficult to filter the acrylic resin using a polymer filter. In addition, since the polymer filter has a structure in which the resin stays easily, there is a problem that the acrylic resin further accelerates the heat deterioration in the staying portion, and the colored deterioration products and bubbles are mixed into the product.

  On the other hand, since a polymer filter distributes a molten resin in a filter having a complicated structure, resin stays easily in the polymer filter, and various proposals have been made to solve this problem.

  For example, in Patent Document 1, an internal flow type center pole is used to solve the problem by communicating the threaded portion of the bolt with the filter medium passage collecting portion of the center pole.

In Patent Document 2, the residence is reduced by doubling the resin path in the center pole of the polymer filter.
JP 2002-273728 A (published September 25, 2002) JP 2002-283344 A (published on October 3, 2002)

  However, the above method causes a problem that it is difficult to stably obtain an acrylic resin excellent in appearance and physical properties.

  Specifically, the method of Patent Document 1 has a problem that the reproducibility of the resistance of the minute gap including the screw portion cannot be obtained, and the effect is lost when the resistance is completely blocked by the deteriorated resin.

  Further, the method of Patent Document 2 has a problem that since the distribution channel is very long, the resin deterioration easily proceeds, the apparatus is complicated, and the installation of the apparatus is limited.

  Further, each of the above solutions has a distribution path that goes downward, and has a problem that deteriorated low-viscosity resin and bubbles easily stay in the filter.

  The present invention has been made in view of the above-mentioned problems, and its purpose is to realize a heat-resistant acrylic resin excellent in appearance and physical properties, and a filtration method and a production method capable of stably providing the heat-resistant acrylic resin. There is to do.

  The present inventor has intensively studied to solve the above problems. As a result, when the acrylic resin is melt filtered using a polymer filter having a filtration accuracy of 15 μm or less, a heat-resistant acrylic resin is used as the acrylic resin, and the product is filtered through a polymer filter having a specific structure. The present inventors have found that it is possible to prevent air bubbles, foreign matters, and deteriorated resin from being mixed therein, and have completed the present invention.

  That is, in order to solve the above problems, the heat-resistant acrylic resin filtration method according to the present invention includes a housing, a center pole, a leaf disk filter having a filtration accuracy of 15 μm or less, and a press disk positioned upstream of the leaf disk filter. And a heat-resistant acrylic resin filtration method using a polymer filter comprising a cap having a bolt for fixing the holding disc to the center pole, wherein the polymer filter has a seal ring in the clearance between the center pole and the holding disc. It is characterized by having.

  According to the above method, since the clearance is provided with the seal ring, it is possible to prevent the resin from flowing into the bolt portion from the clearance between the center pole and the holding disc. For this reason, mixing of a foreign material, a resin deterioration thing, foaming, etc. can be prevented, and there exists an effect that the heat resistant acrylic resin excellent in the external appearance and the physical property can be manufactured stably.

  The above invention comprises a housing, a center pole, a leaf disk filter having a filtration accuracy of 15 μm or less, a pressing disk positioned upstream of the leaf disk filter, and a cap having a bolt for fixing the pressing disk to the center pole. In other words, the heat-resistant acrylic resin filtration method using a polymer filter, in which a seal ring is attached to the clearance of the holding disc.

  In the heat-resistant acrylic resin filtration method according to the present invention, the heat-resistant acrylic resin has the following general formula (1).

(In the formula, R ¹ , R ² and R ³ each independently represents a hydrogen atom or an organic residue having 1 to 20 carbon atoms. The organic residue may contain an oxygen atom.)
It preferably has a lactone ring structure represented by

  According to the above method, since the polymer having a lactone ring structure has a high cyclization condensation reaction rate, bubbles and silver streaks can be prevented from being mixed into the molded product. A polymer having a lactone ring structure has high heat resistance due to the lactone ring structure. Therefore, a heat-resistant acrylic resin excellent in appearance and heat resistance can be stably produced.

  In order to solve the above-mentioned problems, the method for producing a heat-resistant acrylic resin according to the present invention is characterized by including a step of filtering by the heat-resistant acrylic resin filtration method according to the present invention.

  According to the above method, it is possible to prevent foreign matters, resin degradation products, foaming, and the like from being mixed during filtration, and it is possible to stably produce a heat-resistant acrylic resin excellent in appearance and physical properties.

  In order to solve the above-mentioned problems, the heat-resistant acrylic resin according to the present invention is characterized in that the number of foreign matters of 20 μm or more is 100/100 g or less, and the colored deterioration product is 30 ppm or less in terms of mass.

  According to the said structure, there exists an effect that the heat resistant acrylic resin excellent in the external appearance and the physical property can be provided.

  As described above, the heat-resistant acrylic resin filtration method according to the present invention includes a housing, a center pole, a leaf disc filter having a filtration accuracy of 15 μm or less, a press disc positioned upstream of the leaf disc filter, and a press disc. A heat-resistant acrylic resin filtration method using a polymer filter having a cap having a bolt for fixing to a center pole, wherein the polymer filter has a seal ring in the clearance between the center pole and the holding disc. It is a feature.

  For this reason, there exists an effect that it becomes possible to obtain efficiently the foreign resin suitable for optical use, the acrylic resin material with few coloring degradation products, and an acrylic resin molding.

  As described above, the method for producing a heat-resistant acrylic resin according to the present invention is characterized by including the step of filtering by the method for filtering a heat-resistant acrylic resin according to the present invention.

  For this reason, there exists an effect that it becomes possible to obtain efficiently the foreign resin suitable for optical use, the acrylic resin material with few coloring degradation products, and an acrylic resin molding.

  In addition, the heat-resistant acrylic resin according to the present invention is characterized in that the foreign matter having a size of 20 μm or more is 100 pieces / 100 g or less, and the colored deterioration product is 30 ppm or less in terms of mass.

  For this reason, there exists an effect that the heat-resistant acrylic resin excellent in the external appearance and the physical property can be provided.

  Hereinafter, the present invention will be described in detail. However, the scope of the present invention is not limited to these descriptions, and modifications other than the following examples can be made as appropriate without departing from the spirit of the present invention.

  In the present specification, “(meth) acrylic acid” means acrylic acid or methacrylic acid, and “ppm” means a value calculated in terms of mass unless otherwise specified. For example, 10,000 ppm is 1 mass. Means%. In addition, “weight” is treated as a synonym for “mass”, “weight%” is treated as a synonym for “mass%”, and “A to B” indicating a range indicates A or more and B or less.

  In addition, the term “foreign matter” in this specification refers to contaminants mixed in all the processes from polymerizing raw materials to obtaining molded articles such as pellets, and by-products such as gels generated during the polymerization reaction. It means all substances having properties that are not compatible with thermoplastic resins, including by-products caused by deterioration of resins such as carbides generated in extrusion and devolatilization processes.

  The filtration method of the heat-resistant acrylic resin according to the present embodiment includes a housing, a center pole, a leaf disk filter having a filtration accuracy of 15 μm or less, a pressing disk positioned upstream of the leaf disk filter, and the pressing disk as a center pole. A heat-resistant acrylic resin filtration method using a polymer filter including a cap having a bolt to be fixed, and the polymer filter includes a seal ring at a clearance between the center pole and the pressing disk.

  And the manufacturing method of the heat resistant acrylic resin which concerns on this Embodiment includes the process of filtering a heat resistant acrylic resin with the said filtration method.

<Heat resistant acrylic resin>
The heat-resistant acrylic resin refers to a resin having a glass transition temperature of 110 ° C. or higher copolymerized with a (meth) acrylate monomer, preferably 115 ° C. or higher, more preferably 120 ° C. or higher, and still more preferably 130. More than 135 degreeC, Most preferably, it is 135 degreeC or more. Specifically, a copolymer of maleic anhydride and (meth) acrylate, a copolymer of N-substituted maleimide and (meth) acrylate, or a (meth) acrylate copolymer is converted into a lactone ring by intramolecular cyclization reaction. So-called glutaric anhydride polymer and (meth) acrylate copolymer into which intramolecular cyclization reaction of so-called lactonized polymer and (meth) acrylate copolymer into which the structure has been introduced are introduced into the molecule. Examples include so-called glutarimide polymers in which a glutarimide ring structure is introduced by a cyclization reaction.

  Here, the glass transition temperature is a temperature at which a polymer molecule starts micro-Brownian motion, and there are various measurement methods. In this specification, a midpoint according to ASTM-D-3418 using a differential scanning calorimeter (DSC). It is defined as the temperature obtained by the law. Acrylic resins having a glass transition temperature of 110 ° C. or higher are generally recognized as heat-resistant acrylic resins by those skilled in the art.

  As the (meth) acrylate monomer, a (meth) acrylic acid ester having any one of an alkyl group having 1 to 18 carbon atoms, a cyclohexyl group, and a benzyl group is preferable. Specifically, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, (meth) T-butyl acrylate, amyl (meth) acrylate, isoamyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, decyl (meth) acrylate, lauryl (meth) acrylate, Examples include cyclohexyl (meth) acrylate, benzyl (meth) acrylate, 2-phenoxyethyl (meth) acrylate, 3-phenylpropyl (meth) acrylate, 2-hydroxylethyl (meth) acrylate, and the like. Of these, methyl methacrylate is particularly preferred. These (meth) acrylic acid esters may be used alone or in a suitable mixture of two or more.

  Moreover, these may have the unit which copolymerized the other monomer component which can be copolymerized in the range which does not impair heat resistance. Specific examples of other monomer components that can be copolymerized include aromatic vinyl monomers such as styrene and α-methylstyrene, nitrile monomers such as acrylonitrile, vinyl esters such as vinyl acetate, and the like. Is mentioned.

  Furthermore, for the filtration method of the present embodiment, a polymer containing a ring structure in the main chain as the heat-resistant acrylic resin is suitable, and the lactone ring structure is converted into a (meth) acrylate copolymer by an intramolecular cyclization reaction. Most effective when used in a so-called lactone ring-containing polymer.

  The lactone ring-containing polymer preferably has a lactone ring structure represented by the general formula (1).

  The organic residue in the general formula (1) is not particularly limited as long as it has a carbon number in the range of 1 to 20, but for example, a linear or branched alkyl group, a linear or branched alkylene Group, aryl group, -OAc group, -CN group and the like.

  The content of the lactone ring structure represented by the general formula (1) in the lactone ring-containing polymer structure is preferably 5 to 90% by mass, more preferably 10 to 70% by mass, and still more preferably 10 to 60% by mass. Especially preferably, it is 10-50 mass%. When the content of the lactone ring structure represented by the general formula (1) in the lactone ring-containing polymer structure is less than 5% by mass, heat resistance, solvent resistance, and surface hardness may be insufficient. It is not preferable. If the content of the lactone ring structure represented by the general formula (1) in the lactone ring-containing polymer structure is more than 90% by mass, the molding processability may be poor, which is not preferable.

  The lactone ring-containing polymer has a weight average molecular weight of preferably 1,000 to 2,000,000, more preferably 5,000 to 1,000,000, still more preferably 10,000 to 500,000, and particularly preferably. Is 50,000 to 500,000.

  The lactone ring-containing polymer preferably has a mass reduction rate of 150% to 300 ° C. in dynamic TG measurement of 1% or less, more preferably 0.5% or less, still more preferably 0.3% or less. is there.

  Since the lactone ring-containing polymer has a high cyclization condensation reaction rate, it is possible to avoid the disadvantage that bubbles and silver streaks enter the molded product after molding. Furthermore, since the lactone ring structure is sufficiently introduced into the polymer due to a high cyclization condensation reaction rate, the obtained lactone ring-containing polymer has sufficiently high heat resistance.

  The lactone ring-containing polymer preferably has a coloring degree (YI) in a 15% by mass chloroform solution of 10 or less, more preferably 6 or less, still more preferably 3 or less, and most preferably 1 or less. When the coloring degree (YI) exceeds 10, transparency may be impaired by coloring, and it may not be used for the intended purpose.

  The lactone ring-containing polymer preferably has a 5% mass reduction temperature in thermogravimetric analysis (TG) of 280 ° C. or higher, more preferably 290 ° C. or higher, and further preferably 300 ° C. or higher. The 5% mass reduction temperature in thermogravimetric analysis (TG) is an index of thermal stability, and if it is less than 280 ° C., sufficient thermal stability may not be exhibited.

  The total amount of residual volatile components contained in the lactone ring-containing polymer is preferably 5,000 ppm or less, more preferably 2,000 ppm or less. If the total amount of residual volatile components is more than 5,000 ppm, it may be colored due to alteration during molding, foaming, or molding defects such as silver streak.

[Other thermoplastic resins and additives]
The heat-resistant acrylic resin may contain other thermoplastic resins and additives as long as the heat resistance, optical properties, and mechanical properties of the extruded product are not impaired. Other thermoplastic resins include, for example, olefin polymers such as polyethylene, polypropylene, ethylene-propylene copolymer, poly (4-methyl-1-pentene); halogen-containing polymers such as vinyl chloride and chlorinated vinyl resins. Acrylic polymers such as polymethyl methacrylate; styrene polymers such as polystyrene, styrene-methyl methacrylate copolymer, styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene block copolymer; polyethylene terephthalate, polybutylene terephthalate , Aromatic polyesters such as polyethylene naphthalate; aliphatics such as polylactic acid, polybutylene succinate, polybutylene succinate adipate, polyethylene succinate, polyethylene succinate adipate Reester; Polyamide such as nylon 6, nylon 66, nylon 610, etc .; Polyacetal; Polycarbonate; Polyphenylene oxide; Polyphenylene sulfide; Polyether ether ketone; Polysulfone; Polyethersulfone; And rubber polymers such as ABS resin and ASA resin blended with rubber; and the like.

  Thermoplastic resins compatible with lactone ring-containing polymers include copolymers containing vinyl cyanide monomer units and aromatic vinyl monomer units, specifically acrylonitrile-styrene. Examples thereof include polymers containing 50% by mass or more of a copolymer, polyvinyl chloride resin, and methacrylic acid esters. Among them, acrylonitrile-styrene copolymer has the highest compatibility, and a transparent molded product can be obtained without impairing heat resistance.

  In addition, it is confirmed by measuring the glass transition point of the thermoplastic resin composition obtained by mixing these that the lactone ring-containing polymer and other thermoplastic resins are thermodynamically compatible. Can do. Specifically, only one point of the glass transition point measured by the differential scanning calorimeter is observed for the mixture of the lactone ring-containing polymer and the other thermoplastic resin, so that the thermodynamic compatibility is achieved. I can say that.

  When an acrylonitrile-styrene copolymer is used as another thermoplastic resin, an emulsion polymerization method, a suspension polymerization method, a solution polymerization method, a bulk polymerization method, or the like can be used as the production method. From the viewpoint of transparency and optical performance in the case of obtaining a polymer, it is preferably obtained by a solution polymerization method or a bulk polymerization method.

  Examples of the additive include hindered phenol-based, phosphorus-based, and sulfur-based antioxidants; light-resistant stabilizers, weather-resistant stabilizers, thermal stabilizers, and other stabilizers; reinforcing materials such as glass fibers and carbon fibers; UV absorbers such as phenyl salicylate, (2,2′-hydroxy-5-methylphenyl) benzotriazole, 2-hydroxybenzophenone; near infrared absorbers; tris (dibromopropyl) phosphate, triallyl phosphate, antimony oxide, etc. Flame retardants; antistatic agents such as anionic, cationic and nonionic surfactants; colorants such as inorganic pigments, organic pigments and dyes; organic fillers and inorganic fillers; resin modifiers; organic fillers and inorganics Fillers; plasticizers; lubricants; antistatic agents; flame retardants;

  The content ratios of the other thermoplastic resins and additives in the heat-resistant acrylic resin are preferably in the range of 0 to 5% by mass, more preferably in the range of 0 to 2% by mass, and still more preferably 0 to 0%. Within the range of 5% by mass. The additive may be added before the heat-resistant acrylic resin is charged into the extruder described later, or may be added simultaneously when the heat-resistant acrylic resin is charged into the extruder. It may be added after the heat-resistant acrylic resin has been added to.

(Extruder)
The heat-resistant acrylic resin is plasticized by an extruder before being filtered by a polymer filter. The extruder used for the plasticization can be applied to either a single screw extruder or a multi-screw extruder. In order to obtain a sufficient plasticization and kneading state, L / D (L is the cylinder length of the extruder and D is the cylinder inner diameter) is preferably 10 or more and 100 or less, more preferably 20 or more and 50 or less, 25 More preferably, it is 40 or less. If L / D is 10 or less, it is difficult to obtain a sufficient plasticization or kneading state. If L / D is 100 or more, excessive shearing heat generation is applied to the resin, and the resin may be decomposed.

  The set temperature of the cylinder is preferably 200 ° C. or higher and 330 ° C. or lower, and more preferably 220 ° C. or higher and 300 ° C. or lower. At 200 ° C. or lower, the melt viscosity of the resin becomes high, so that an unnecessarily high power and L / D necessary for plasticization are required, which hinders productivity. If it exceeds 330 ° C, the resin may be decomposed.

  Moreover, it is more preferable to install a gear pump between the extruder and the filter to stabilize the resin pressure in the filter regardless of the single-screw extruder, twin-screw extruder, or multi-screw extruder.

  In addition, the plasticizing method does not particularly define the shape of the extruder. However, it is more preferable that the extruder has one or more open vent portions and sucks the decomposition gas generated in a reduced pressure state. It is preferable because an increase in the amount can be suppressed. When making an open vent part into a pressure-reduced state, the range of 931-1.3 hPa (700-1 mmHg) is preferable, and the range of 798-13.3 hPa (600-10 mmHg) is more preferable. When the pressure is higher than 931 hPa, residual volatile components in the molten resin, monomer components generated by resin decomposition, and the like are likely to remain. Moreover, when lower than 1.3 hPa, there exists a problem that industrial implementation will become difficult.

[Polymer filter]
Examples of the polymer filter used in the present embodiment include a polymer filter in which a large number of leaf disk filters (hereinafter sometimes abbreviated as “leaf disk filters”) are arranged in a housing.

  FIG. 1 is a cross-sectional view showing a schematic configuration of a general polymer filter excluding a housing. As shown in FIG. 1, the polymer filter includes a plurality of leaf disk filters 7 and a center pole (inner flow type center pole) 4 having a support for the leaf disk filter 7 and a flow path after filter filtration. It has a structure in which spacers 6 having a rectifying effect are alternately stacked. In order to avoid the inflow of unfiltered resin from the primary side of the filter, a gasket 5 is arranged between each leaf disk filter 7 and the spacer 6, and the pressure is applied by the holding disk 3 and bolted by the cap 1. .

  Further, in the case of the internal flow type center pole 4, gas and resin degradation products due to resin retention are likely to stay in the resin flow channel located in the uppermost stream portion in the center pole 4. It is possible to arrange the torpedo 12 having a pyramid structure such as a pyramid to rectify the resin flow and suppress the stay. However, even in the polymer filter structure in which the above-described two speeds 12 are arranged, there is a slight gap between the outer peripheral surface of the center pole 4 and the presser disk 3, and under the high resin pressure, the gap passes through the gap. Intrusion of the filtered resin into the bolt cannot be avoided.

  FIG. 2 is a cross-sectional view showing a schematic configuration of an example of the polymer filter according to the present embodiment excluding the housing. As shown in FIG. 2, the polymer filter has a structure in which a seal ring 10 is arranged in the clearance between the center pole (outer flow type center post) 9 and the pressing disk 3, and the other configuration is the polymer shown in FIG. It is almost the same as the filter. The outer flow type center pole 9 is provided with a resin flow path having a structure that does not have a portion corresponding to the staying portion located in the uppermost stream portion in the inner flow type center pole 4 described above, and gas caused by resin staying. And resin degradation can be suppressed.

  Further, in this specification, a case where the center pole of the polymer filter is an external flow type center post as shown in FIG. 2 will be described, but the scope of the present invention is not limited to this. The center pole may be the internal flow type center pole shown in FIG. In either case, the same effect can be obtained if the seal ring 10 is arranged in the clearance between the center pole and the holding disc 3.

  The filter medium in the leaf disc filter 7 may be any of a type in which a metal fiber non-woven fabric is sintered, a type in which metal powder is sintered, a type in which several metal meshes are laminated, or a hybrid type in which they are combined. A type in which a nonwoven fabric is sintered is most preferable.

  Further, the filtration accuracy of the leaf disc filter 7 is 15 μm or less, more preferably 10 μm or less, and most preferably 5 μm or less. If it is 1 μm or less, the filtration residence time becomes long, which is not preferable from the viewpoint of thermal degradation of the resin and productivity, and therefore the filtration accuracy is more preferably over 1 μm. On the other hand, if the thickness exceeds 15 μm, foreign matter is likely to be mixed, which is not preferable.

The filtration area with respect to the resin treatment amount per hour of the polymer filter is not particularly limited and is appropriately set according to the treatment amount, and is, for example, 0.001 to 0.15 m ² / (kg / h).

  The shape of the center pole 9 is not particularly limited. For example, as shown in FIGS. 3B to 3D, the cross section is in contact with the inner peripheral surface of the leaf disk filter at a plurality of vertices or faces. 9 is an external flow type having a resin flow path on the outer surface. Further, when the center pole is an internal flow type center pole, for example, as shown in a cross-sectional shape in FIG. 3A, there are a plurality of resin flow ports, and an internal flow type having a resin flow path in the center pole. Is mentioned. Among these, an external flow type with a few staying places in the resin flow path is more preferable.

  In the polymer filter according to the present embodiment, the seal ring 10 is attached to the clearance between the center pole 9 of the polymer filter and the pressing disk 3.

  The seal ring 10 can prevent the resin from flowing into the bolt portion from the clearance between the center pole 9 and the holding disc 3. In particular, in the case of acrylic resin, depolymerization and main chain cleavage are likely to occur at a temperature of 220 ° C. or higher. For example, even if a heat-resistant acrylic resin is used, if there is no seal ring 10 as shown in FIG. Resin enters the dead space (retention location 8) and stays and deteriorates. During continuous filtration, when the pressure in the retention part (retention part 8) becomes higher than the pressure in the polymer filter, the decomposed gas components and colored deterioration products flow out, Invite bubbles and colored materials inside.

  Here, the colored deterioration product refers to a resin having a color difference of 50 μm or more, which is recognized as a defect when formed into a molded product. Further, for example, in the case of a film molded product, it may be difficult to see the color of the colored degradation product, but it appears as a defect in the film due to holes, a flow pattern, a flow line, or the like.

  When the heat-resistant acrylic resin obtained by the method according to the present embodiment and the film molded body thereof are used for an optical material, the content of the colored product is preferably 30 ppm or less, more preferably 20 ppm or less, and still more preferably 10 ppm or less, Most preferably, it is 0 ppm.

  The cross-sectional shape of the seal ring 10 is not particularly limited, but may be any shape that can seal the clearance between the center pole 9 and the presser disk 3, and FIGS. 4 (a) to 4 (e) and the like. As shown in FIG. That is, the cross-sectional shape of the seal ring 10 may be a square such as a square or a rectangle (see FIGS. 4A and 4C), or may be a circle or an ellipse (see FIG. 4). (See (b) of FIG. 4), or a triangle (see (c) of FIG. 4) or an L-shape (see (d) of FIG. 4).

  In particular, the configuration shown in FIG. 4C in which the cross-sectional shape is a triangle, which is obliquely in contact with the presser disc 3 and slightly protrudes from the bottom of the presser disc 3 is the seal ring due to the pressure when the leaf disc filter 7 is attached. Since 10 is tightened to the center pole 9 side and the sealing performance is improved, this is a preferable mode.

  The material of the seal ring 10 is not particularly limited, and examples thereof include plastics such as Teflon (registered trademark) and metals such as stainless steel, aluminum, titanium, and copper, and metals are preferable because of resistance to pressure.

  The polymer filter is preferably installed upward from the upstream side of the resin toward the downstream side at an angle in which the axis of the center pole 9 exceeds the horizontal with respect to the ground and is 90 degrees or less. That is, the polymer filter is preferably installed with the cap 1 side of the center pole 9 facing downward.

  For example, when installed downward with respect to the ground (when installed with the cap 1 side of the center pole 9 facing upward), low-viscosity resin and bubbles tend to stay. The most preferable form is a case where the center pole 9 is installed perpendicular to the ground with the cap 1 side of the center pole 9 facing downward.

  Although there is no restriction | limiting in particular about the residence time at the time of filtration with the said polymer filter, Preferably it is 20 minutes or less, More preferably, it is 10 minutes or less, Most preferably, it is 5 minutes or less. Further, the filter inlet pressure and the filter outlet pressure during filtration are, for example, in the range of 3 to 15 MPa and 0.3 to 10 MPa, respectively, and the pressure loss (the pressure difference between the filter inlet pressure and the outlet pressure) is 1 MPa to 15 MPa. It is preferable to be within the range. When the pressure loss is 1 MPa or less, the flow path through which the polymer passes through the filter tends to be biased, and the quality tends to deteriorate. Conversely, if the pressure exceeds 15 MPa, the filter is easily damaged.

  The resin temperature of the heat-resistant acrylic resin introduced into the polymer filter is appropriately set in accordance with the viscosity, but is in the range of 220 to 320 ° C, preferably in the range of 240 to 300 ° C, and most preferably in the range of 260 to 280 ° C. It is a range.

  To obtain a final molded product with less foreign matter and colored matter by filtration with a polymer filter 1) Process of filtering in a clean environment at the time of polymer production and subsequent molding in a clean environment 2) Foreign matter and colored matter A process that performs filtration in a clean environment and then molding in a clean environment, and 3) a process that performs filtration in a clean environment while simultaneously forming a polymer containing foreign matter and colored substances, etc. The polymer filter treatment may be performed a plurality of times for each step.

  By the manufacturing method described above, it is possible to obtain a heat-resistant acrylic resin in which foreign matter having a size of 20 μm or more is 100 pieces / 100 g or less and a colored deterioration product is 30 ppm or less in terms of mass. It is particularly suitable for stable production, and specifically enables continuous production of 1 t or more.

  More preferably, the number of foreign matters of 20 μm or more can be 40 pieces / 100 g or less, and particularly preferably 30 pieces / 100 g or less.

  Further, the colored deterioration product can be more preferably 15 ppm or less in terms of mass, further preferably 10 ppm or less in terms of mass, and most preferably 0 ppm in terms of mass.

  The hue of the heat-resistant acrylic resin filtered by the filtration method according to the present embodiment is not particularly limited, but it is preferable that it is transparent and has a smaller yellowing degree because it does not impair the original characteristics of the acrylic resin.

  Further, the heat-resistant acrylic resin filtered by the filtration method according to the present embodiment has a haze value of 3 or less, more preferably 2 or less, and most preferably 1 or less when formed into a 3 mm thick molded body, for example. Further, the coloration degree (YI) in a 15% by mass chloroform solution is 10 or less, preferably 6 or less, more preferably 3 or less, and most preferably 1 or less.

  Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited to these. Hereinafter, for convenience, “mass part” may be simply referred to as “part”, and “liter” may be simply referred to as “L”.

  The polymer filter used in this example is a leaf disk type polymer filter having an external flow type center pole shown in FIG. 2, and is located upstream of the housing, the center pole, the leaf disk filter, and the leaf disk filter. At least a pressing disk and a cap having a bolt for fixing the pressing disk to the center pole are provided. In addition, the said center pole used the thing of the shape shown in FIG.3 (b), and the seal ring used the thing of the shape shown in FIG.4 (c).

<Polymerization reaction rate, polymer composition analysis>
The reaction rate during the polymerization reaction and the content of the specific monomer unit in the polymer were determined by gas chromatography (manufactured by Shimadzu Corporation, apparatus name: GC17A) based on the amount of unreacted monomer in the obtained polymerization reaction mixture. ) And measured.

<Dynamic TG>
The polymer (or polymer solution or pellet) is once dissolved or diluted in tetrahydrofuran, poured into excess hexane or methanol for reprecipitation, and the taken out precipitate is vacuum dried (1 mmHg (1.33 hPa), 80 ° C. Volatile components and the like were removed by conducting the reaction for 3 hours or more, and the obtained white solid resin was analyzed by the following method (dynamic TG method).
Measuring apparatus: Thermo Plus2 TG-8120 Dynamic TG (manufactured by Rigaku Corporation)
Measurement conditions: Sample amount 5 to 10 mg
Temperature increase rate: 10 ° C / min
Atmosphere: Nitrogen flow 200ml / min
Method: Step-like isothermal control method (controlled at a mass reduction rate of 0.005% / sec or less between 60 ° C and 500 ° C)
<Dealcoholization reaction rate and proportion of lactone ring structure>
The dealcoholization reaction rate was determined based on the amount of mass loss that occurred when all hydroxyl groups were dealcoholated as methanol from the polymer composition obtained by polymerization, and from 150 ° C. before the mass loss began in dynamic TG measurement, It calculated | required from the mass reduction by the dealcoholization reaction to 300 degreeC before decomposition | disassembly started.

That is, in the dynamic TG measurement of the polymer having a lactone ring structure, the mass reduction rate between 150 ° C. and 300 ° C. is measured, and the obtained actual mass reduction rate is defined as (X). On the other hand, from the composition of the polymer, all the hydroxyl groups contained in the polymer composition are involved in the formation of the lactone ring, so that it becomes an alcohol and is dealcoholized. The mass reduction rate calculated on the assumption that a% dealcoholization reaction has occurred is defined as (Y). The theoretical mass reduction rate (Y) is more specifically the molar ratio of the raw material monomers having a structure (hydroxyl group) involved in the dealcoholization reaction in the polymer, that is, the raw material unit in the polymer composition. It can be calculated from the content of the monomer. These values (X, Y) are calculated from the dealcoholization formula:
1- (actual mass reduction rate (X) / theoretical mass reduction rate (Y))
Substituting into, the value is obtained and expressed in% to obtain the dealcoholization reaction rate. And it prescribes | regulates that predetermined | prescribed lactone cyclization was performed only by this dealcoholization reaction rate.

  Here, the proportion of the lactone ring structure in the pellets obtained in Production Example 1 described later is calculated. When the theoretical weight loss rate (Y) of this polymer was determined, the molecular weight of methanol was 32, the molecular weight of methyl 2- (hydroxymethyl) acrylate was 116, and methyl 2- (hydroxymethyl) acrylate. Since the content (mass ratio) in the polymer is 20.0% by mass in terms of composition, (32/116) × 20.0≈5.52% by mass.

On the other hand, the actual mass reduction rate (X) by dynamic TG measurement was 0.15% by mass. When these values are applied to the above-mentioned formula for the dealcoholization reaction rate,
(1- (0.15 / 5.52)) ≈0.973
And the dealcoholization reaction rate is 97.3%.

Then, assuming that the lactone cyclization reaction was performed by the amount corresponding to the dealcoholization reaction rate, the content ratio (mass%) of the following formula lactone ring = B × A × M _R / M _m
(Wherein, B is the mass proportion in the monomer composition used in the copolymerization raw monomer having a structure (hydroxyl group) responsible for the lactonization, M _R lactone ring structure to generate The unit formula weight, M _m is the molecular weight of the raw material monomer having a structure (hydroxyl group) involved in lactone cyclization, and A is the dealcoholization reaction rate)
Thus, the lactone ring content ratio can be calculated.

  In the case of Production Example 1, the content of 2- (hydroxymethyl) methyl acrylate in the polymer is 20.0% by mass, the calculated dealcoholization reaction rate is 97.3%, and the molecular weight is 116. 2- (hydroxymethyl) Since the formula amount of the lactone ring structural unit produced when methyl acrylate is condensed with methyl methacrylate is 170, the content of the lactone ring in the polymer is 28.5 (= 20.0 × 0. 973 × 170/116) mass%.

<Weight average molecular weight>
The weight average molecular weight of the polymer was determined by polystyrene conversion of GPC (GPC system manufactured by Tosoh Corporation). Chloroform was used as the developing solution.

<Thermal analysis of resin>
The thermal analysis of the resin was performed using DSC (manufactured by Rigaku Corporation, apparatus name: DSC-8230) under the conditions of about 10 mg of sample, a heating rate of 10 ° C./min, and a nitrogen flow of 50 cc / min. The glass transition temperature (Tg) was determined by the midpoint method according to ASTM-D-3418.

<Melt flow rate>
The melt flow rate was measured at a test temperature of 240 ° C. and a load of 10 kg based on JIS-K7210.

<Quantification of MMA residual components>
The pellet was dissolved in dimethylacetamide to prepare a 10% by mass solution, and quantified by gas chromatography using diphenyl carbonate as an internal standard substance.

<Yellow Index (YI)>
A solution obtained by dissolving a molded product in chloroform so as to be 15% by mass is put in a quartz cell, and a color difference meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name: SZ-Σ90) is used according to JIS K-7103. , Measured with transmitted light.

<Melt viscosity>
The fully dried pellet was measured using a capillary rheometer RH10 manufactured by Borin Instruments.

<Number of foreign objects>
Dissolve the molded product in a purified chloroform solution so as to be 20% by mass, suck with a Teflon (registered trademark) filter having a diameter of 47 mm and a filtration accuracy of 1 μm, and remove the foreign matter remaining on the Teflon (registered trademark) filter. It was measured visually under a microscope. Note that the foreign matter having a size of 20 μm or more means a foreign matter having the largest diameter of the foreign matter of 20 μm or more.

<Colored degradation product content (average color content)>
Using a pellet inspection system manufactured by Optical Control Systems, colored foreign matter in 10 kg of pellets was measured. Sensitivity was adjusted so that a colored material of 50 μm or more could be detected, and the content of the colored material was determined as follows. That is, assuming that the detected colored material is spherical, the volume is obtained from the average of the long diameter and the short diameter obtained from the image, and the total amount of colored substances contained in 10 kg is calculated from the product of the volume and the resin density. did.

  In addition, about the measurement conditions, it confirmed whether the said colored material was recognized by visual observation under a microscope, and set the measurement sensitivity.

[Production Example 1]
In a 1 m ³ reaction kettle equipped with a stirrer, temperature sensor, cooling pipe, and nitrogen introduction pipe, 136 kg of methyl methacrylate (MMA), 34 kg of methyl 2- (hydroxymethyl) acrylate (MHMA), and 166 kg of toluene were added. At the same time, 187 g of tertiary amyl peroxy isononanoate (manufactured by Atofina Yoshitomi, trade name: Lupazole 570) was added as an initiator at the same time as 374 g. Solution polymerization was performed under reflux (about 105 to 110 ° C.) while dropwise adding a solution composed of an initiator and 3.6 kg of toluene over 2 hours, and further aging was performed for 4 hours.

  170 g of stearyl phosphate / distearyl phosphate mixture (manufactured by Sakai Chemicals, product name: Phoslex A-18) was added to the resulting polymer solution and cyclized under reflux (about 90 to 110 ° C.) for 5 hours. A condensation reaction was performed. Subsequently, the polymer solution obtained by the cyclization condensation reaction was subjected to a vent having a barrel temperature of 250 ° C., a rotation speed of 150 rpm, a degree of vacuum of 13.3 to 400 hPa (10 to 300 mmHg), a rear vent of 1 and a forevent of 4 It is introduced into a type screw twin screw extruder (φ = 42 mm, L / D = 42) at a processing rate of 13 kg / h in terms of the amount of resin, subjected to cyclization condensation reaction and devolatilization in the extruder, and then extruded. Thus, a transparent pellet was obtained.

  When the obtained pellet was measured by dynamic TG, a mass decrease of 0.15% by mass was detected. The lactone ring-containing polymer has a weight average molecular weight of 147,000, a melt flow rate of 11.0 g / 10 min, a glass transition temperature of 130 ° C., a viscosity of 270 ° C. and a shear rate of 100 (/ s) at a viscosity of 470 Pa · s.

[Production Example 2]
A 1 m ³ reaction kettle equipped with a stirrer, temperature sensor, cooling pipe, and nitrogen introduction pipe was charged with 113 kg of methyl methacrylate (MMA), 44.8 kg of cyclohexylmaleimide (CHMI), and 179 kg of toluene. Then, when the temperature was raised to 100 ° C. and refluxed, 0.108 kg of t-butylperoxyisopropyl carbonate (manufactured by Kayaku Akzo Co., Ltd., trade name: Kaya-Carbon BIC-75) was added as an initiator. Subsequently, a mixture of 113 kg of methyl methacrylate, 44.8 kg of N-cyclohexylmaleimide, 43 kg of styrene, 179 kg of toluene and 0.58 kg of t-butylperoxyisopropyl carbonate was previously added to the reaction vessel with nitrogen. It was bubbled with gas, dropped over 3.5 hours, solution polymerization was performed under reflux (about 110 ° C.), and aging was further performed over 3.5 hours.

  Next, the polymer solution was subjected to a vent type screw twin screw extruder (φ) having a barrel temperature of 240 ° C., a rotation speed of 150 rpm, a degree of vacuum of 13.3 to 400 hPa (10 to 300 mmHg), a rear vent number of 1, and a forevent number of 4. = 42 mm, L / D = 42) was introduced at a treatment rate of 13 kg / hour in terms of resin amount, devolatilized, and extruded to obtain transparent pellets.

  The obtained pellets had a weight average molecular weight of 182,000, a melt flow rate of 12.0 g / 10 min, and a glass transition temperature of 135 ° C.

[Production Example 3]
A 1 m ³ reaction kettle equipped with a stirrer, temperature sensor, cooling pipe, and nitrogen introducing pipe was charged with 161.5 kg of methyl methacrylate (MMA), 8.5 kg of methyl acrylate, and 160 kg of toluene, and this was charged with nitrogen. The temperature was raised to 100 ° C. and refluxed, and 0.187 kg of tertiary amyl peroxyisononanoate (manufactured by Atofina Yoshitomi, trade name: Lupazole 570) was added as an initiator, and at the same time 0.374 kg was started. While a solution consisting of an agent and 3.6 kg of toluene was added dropwise over 2 hours, solution polymerization was performed under reflux (about 105 to 110 ° C.), followed by further aging for 4 hours.

  Next, the polymer solution was subjected to a vent type screw twin screw extruder (φ) having a barrel temperature of 210 ° C., a rotation speed of 150 rpm, a degree of vacuum of 13.3 to 400 hPa (10 to 300 mmHg), a rear vent number of 1, and a forevent number of 4. = 42 mm, L / D = 42) was introduced at a treatment rate of 13 kg / hour in terms of resin amount, devolatilized, and extruded to obtain transparent pellets.

  The obtained pellets had a weight average molecular weight of 147,000, a melt flow rate of 14.0 g / 10 min, and a glass transition temperature of 103 ° C.

[Example 1]
In a clean room of class 10,000, with a vent having a diameter of 50 mm and L / D = 36 with a polymer filter with a seal ring in the clearance between the center pole and the holding disc (filtration accuracy 5μ, filtration area 1.5m ² ) Using a single-screw extruder, the heat-resistant acrylic resin pellets obtained in Production Example 1 were melt-kneaded and devolatilized at a processing rate of 91 kg / h with 400 ppm of zinc acetate, and simultaneously subjected to filtration and extruded strands. Was solidified in water treated with an organo 1 μ filter to produce 1 t of pellet (1A). At this time, the set temperature of the cylinder and the filter was appropriately adjusted so that the resin temperature of the extruded strand was 280 ° C., and the pressure at the polymer filter inlet was 10.0 MPa. In this example, it was possible to continuously produce 1 t or more.

  As a result of visual confirmation, the extruded state of the strand is stable. The obtained pellet (1A) has an MFR of 14 g / 10 min, a residual amount of MMA of 420 ppm, and a coloring degree (YI) when a 15 mass% chloroform solution is used. Was 0.5. In addition, the average number of foreign matters of 20 μm or more using samples collected every 100 kg was 13, and the average amount of colored substances calculated by the pellet inspection system was 0 ppm.

  When the polymer filter was disassembled after completion, no trace of resin retention was observed. The obtained results are shown in Table 1.

[Example 2]
Example 1 except that 90 parts of heat-resistant acrylic resin pellets obtained in Production Example 1, 10 parts of AS resin (trade name: Stylac AS783, manufactured by Asahi Kasei Chemicals Co., Ltd.) and 400 ppm of zinc acetate were used. The pellet (2A) was made 1 t. At this time, the pressure at the polymer filter inlet was 10.0 MPa. In this example, it was possible to continuously produce 1 t or more.

  As a result of visual confirmation, the extruded state of the strand is stable, and the obtained pellet (2A) has an MFR of 14 g / 10 min, a residual amount of MMA of 440 ppm, and a coloring degree (YI) when a 15 mass% chloroform solution is used. Was 3.7. In addition, the average number of foreign matters of 20 μm or more measured from samples collected every 100 kg was 17, and the average amount of colored substances calculated by the pellet inspection system was 0 ppm.

  When the polymer filter was disassembled after completion, no trace of resin retention was observed. The obtained results are shown in Table 1.

Example 3
Except for using the heat-resistant acrylic resin obtained in Production Example 2, 1 t of pellets (3A) was produced in the same manner as in Example 1. At this time, the pressure at the polymer filter inlet was 10.5 MPa. In this example, it was possible to continuously produce 1 t or more.

  As a result of visual inspection, the extruded state of the strand is stable, and the obtained pellet (3A) has an MFR of 13 g / 10 min, a residual amount of MMA of 440 ppm, and a coloring degree (YI) when a 15 mass% chloroform solution is used. Was 8. In addition, the average number of foreign matters of 20 μm or more using samples collected every 100 kg was 24, and the average amount of colored substances calculated by the pellet inspection system was 0 ppm.

  When the polymer filter was disassembled after completion, no trace of resin retention was observed. The obtained results are shown in Table 1.

[Comparative Example 1]
Except that a polymer filter without a seal ring was used for the clearance between the center pole and the holding disc, the same procedure as in Example 1 was carried out. As a result, bubbles were broken in the strands, resulting in frequent breaks in the strands and interruption of pelletization. It was. Further, when the discharge amount was lowered at the time of interruption, a colored resin deterioration product was ejected from the die. For this reason, in Comparative Example 1, continuous production for a long time could not be performed, and production was interrupted about every 400 kg.

  The obtained resin pellet (1B) had an MFR of 14 g / 10 min, a residual amount of MMA of 520 ppm, and a coloration degree (YI) of 1.7% in a 15% by mass chloroform solution. In addition, the average number of foreign matters of 20 μm or more measured from samples collected every 100 kg was 48, and the average amount of colored substances calculated by the pellet inspection system was 36 ppm.

  When the polymer filter was disassembled after completion, the deteriorated colored resin was retained in the dead space between the pressing disk and the bolt. The obtained results are shown in Table 1.

[Comparative Example 2]
The same procedure as in Example 2 was performed except that the polymer filter was not used. At this time, the pressure at the outlet of the extruder was 3 MPa. In this comparative example, it was possible to continuously produce 1 t or more.

  As a result of visual confirmation, the extruded state of the strand is stable, and the obtained pellet (2B) has an MFR of 12 g / 10 min, a residual amount of MMA of 330 ppm, and a coloring degree (YI) when a 15 mass% chloroform solution is used. Was 0.2. In addition, the average number of foreign matters of 20 μm or more measured from samples collected every 100 kg was 350, and the average amount of colored substances calculated by the pellet inspection system was 0.3 ppm. The obtained results are shown in Table 1.

[Comparative Example 3]
Using the acrylic resin obtained in Production Example 3, filtration treatment was performed in the same apparatus as in Example 1.

  The treatment temperature was set to 91 kg / h, and the set temperature of the cylinder and filter was adjusted so that the pressure at the polymer filter inlet was 15 MPa or less. However, pelletization could not be performed due to strand foaming or strand breakage. The resin temperature of the strand at this time was 265 degreeC.

  When the polymer filter was disassembled after completion, no trace of resin retention was observed. The obtained results are shown in Table 1.

[Comparative Example 4]
A pellet (4B) was produced in the same manner as in Example 3 except that the polymer filter was not used. At this time, the pressure at the inlet of the polymer filter was 3 MPa. In this comparative example, it was possible to continuously produce 1 t or more.

  As a result of visual confirmation, the extruded state of the strand is stable, and the resulting pellet (4B) has an MFR of 12 g / 10 min, a residual amount of MMA of 300 ppm, and a coloring degree (YI) when a 15 mass% chloroform solution is used. Was 6.5. In addition, the average number of foreign matters of 20 μm or more using samples collected every 100 kg was 330, and the average amount of colored substances calculated by the pellet inspection system was 0.2 ppm. The obtained results are shown in Table 1.

[Reference Example 1]
Filtration treatment was performed in the same manner as in Comparative Example 1 except that AS resin (manufactured by Asahi Kasei Chemicals Corporation, trade name: Stylac AS783) was used to obtain resin pellets (1C). At this time, the set temperature of the cylinder and the filter was appropriately adjusted so that the resin temperature of the extruded strand was 280 ° C., and the pressure at the polymer filter inlet was 9.7 MPa. In this reference example, it was possible to continuously produce 1 t or more.

  As a result of visual confirmation, the extruded state of the strand was stable, and the degree of coloration (YI) when the obtained resin pellet (1C) was a 15% by mass chloroform solution was 9. The number of foreign matters having a size of 20 μm or more was 36, and the pellet containing the colored material detected by the pellet checker was 5 ppm.

  When the polymer filter was disassembled after completion, the deteriorated colored resin stayed in the dead space between the presser disk and the bolt. The obtained results are shown in Table 1.

Example 4
In a class 10,000 clean room, the heat-resistant acrylic resin pellet (2A) obtained in Example 2 was charged into a single screw extruder with a vent having a φ65 mm, L / D = 32, barrier flight type screw. The temperature of the pellet (2A) was set to around 60 ° C. by blowing dehumidified air heated in a hopper. Further, a nitrogen introduction pipe was provided at the lower part of the hopper, and nitrogen gas was introduced into the extruder. While performing suction at 13 hPa (10 mmHg) from the vent port, the mixture was melt kneaded with a barrier flight type screw. The molten resin was passed through a polymer filter having a seal ring in the clearance between the center pole and the pressing disk using a gear pump, and a film was formed on a 90 ° C. cooling roll from a T die having a width of 700 mm. The temperature of the cylinder, gear pump, polymer filter, and T-die was set to 275 ° C., and the extrusion rate was set to 33 kg / h.

The film thickness of the obtained film was 90 μm, and as a film defect of 20 μm or more observed by visual observation under a microscope, the average number of foreign matters was 3 / m ² . Moreover, when the 100-m roll was inspected, no other film defects were found.

  In this example, it was possible to continuously produce 1 t or more.

[Comparative Example 5]
The same procedure as in Example 4 was performed except that a polymer filter without a seal ring was used for the clearance between the center pole and the holding disc.

The film thickness of the obtained film is 90 μm, and the film defects of 20 μm or more observed by visual observation are: 5 foreign objects / m ² , 2 holes perforated due to deteriorated resin in 100 m roll and flow pattern There were 3 points.

  In this example, it was possible to continuously produce 1 t or more.

  As described above, according to the present invention, an acrylic resin material and an acrylic resin molded article excellent in appearance and physical properties, which are treated with a polymer filter with high filtration accuracy and prevent foreign matters, resin degradation products, foaming and the like from being mixed. Can be provided.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

  In the heat-resistant acrylic resin filtration method according to the present invention, a polymer filter having a seal ring in the clearance between the center pole and the pressing disk is used. For this reason, a heat-resistant acrylic resin excellent in appearance and physical properties can be produced, and such a heat-resistant acrylic resin can be suitably used particularly in fields related to optical materials.

It is sectional drawing which shows schematic structure of the general polymer filter except the housing. It is sectional drawing which shows schematic structure of an example of the polymer filter which concerns on this Embodiment except the housing. It is sectional drawing which shows the example of the cross-sectional shape of the center pole used by this Embodiment. It is sectional drawing which shows the example of the cross-sectional shape of the seal ring used by this Embodiment.

Explanation of symbols

1 Cap 2 Gasket 3 Presser Disc 4 Internal Flow Center Pole (Center Pole)
5 Gasket 6 Spacer 7 Leaf disc filter 8 Retention point 9 Outflow type center post (Center pole)
10 seal ring 11 resin flow path 12 two speed

Claims (4)

A polymer filter including a housing, a center pole, a leaf disk filter having a filtration accuracy of 15 μm or less, a pressing disk positioned upstream of the leaf disk filter, and a cap having a bolt for fixing the pressing disk to the center pole was used. It is a heat-resistant acrylic resin filtration method,
The method for filtering a heat-resistant acrylic resin, wherein the polymer filter includes a seal ring in a clearance between the center pole and the pressing disk. The heat-resistant acrylic resin has the following general formula (1)

(In the formula, R ¹ , R ² and R ³ each independently represents a hydrogen atom or an organic residue having 1 to 20 carbon atoms. The organic residue may contain an oxygen atom.)
The heat-resistant acrylic resin filtration method according to claim 1, which has a lactone ring structure represented by:   A method for producing a heat-resistant acrylic resin, comprising the step of filtering the heat-resistant acrylic resin by the method for filtering a heat-resistant acrylic resin according to claim 1.   A heat-resistant acrylic resin characterized in that the number of foreign matters of 20 μm or more is 100/100 g or less, and the colored deterioration product is 30 ppm or less in terms of mass.

Images