Methods for reusing resin molded products

Abstract

The purpose of the present invention is to provide a method for reusing resin molded articles that include alicyclic-structure-containing polymers, the method making it possible to obtain recycled products of resin molded articles in which defects of appearance are suppressed to a greater extent and properties such as color tone are improved. This method for reusing resin molded articles that include alicyclic-structure-containing polymers is characterized by including: a step for crushing the resin molded articles to obtain a molded article crushed product; and a step for dissolving the molded article crushed product in a mixed solvent that includes 80-98 wt% of cyclohexane and 2-20 wt% of a hydrocarbon-based or aromatic solvent having a freezing point of −40°C or lower, per 100 wt% of the mixed solvent, to obtain a polymer solution.

Description

[Technical Field]

[0001] This invention relates to a method for reusing resin molded articles. [Background technology]

[0002] Thermoplastic resins, such as polymers with alicyclic structures, generally possess excellent properties such as transparency, heat resistance, moisture resistance, chemical resistance, and electrical properties, and are therefore widely used in various fields such as optical materials, medical materials, and electrical component materials. Consequently, a large amount of waste material is generated from molded products containing these alicyclic polymers, as well as processing waste generated during the manufacturing of such molded products. For example, in the manufacture of optical films, thermoplastic resins are usually molded into films by solution extrusion or melt extrusion, stretched as needed, wound into rolls, and supplied as long and wide rolls of film. In this process, the edges of the film are trimmed, and the portion commonly known as the film selvage is generated as waste material.

[0003] In recent years, recycled plastics obtained by collecting waste materials from molded products made of thermoplastic resins, crushing them as needed, and then pelletizing them have been widely used. However, when waste materials from molded products made of polymer resins with an alicyclic structure are reused, physical properties such as strength and color may deteriorate due to residual foreign matter or thermal degradation caused by repeated heat processing, making them unsuitable for their original purpose.

[0004] As a method for reusing waste molded articles made of polymer resins having an alicyclic structure, Patent Document 1 discloses a method for reusing alicyclic structure-containing polymer resin molded articles, characterized by including a step of removing foreign matter from the alicyclic structure-containing polymer resin molded article in a molten or solution state. Patent Document 2 discloses a method for reusing alicyclic structure-containing polymer resin molded articles, characterized by including a step of dissolving the alicyclic structure-containing polymer resin molded article in a solvent and decolorizing it with an adsorbent. Patent Document 3 discloses a method for reusing alicyclic structure-containing polymer resin molded articles, characterized by including a step of hydrogenation treatment. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 11-291247 [Patent Document 2] Japanese Patent Application Publication No. 11-293030 [Patent Document 3] Japanese Patent Application Publication No. 11-293029 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, conventional methods for reusing polymer resin molded articles containing alicyclic structures had room for improvement in obtaining recycled resin molded articles with fewer appearance defects and good physical properties such as color tone.

[0007] Therefore, the present invention aims to provide a method for reusing resin molded articles containing an alicyclic structure-containing polymer, which can obtain recycled resin molded articles with improved physical properties such as color tone and reduced appearance defects. [Means for solving the problem]

[0008] The inventors diligently conducted research with the aim of solving the above problems. As a result, the inventors discovered that by pulverizing a resin molded article containing an alicyclic structure polymer and dissolving it in a mixed solvent containing cyclohexane and a hydrocarbon or aromatic solvent with a freezing point below a predetermined temperature in a predetermined ratio, it is possible to obtain a recycled resin molded article with reduced appearance defects and improved physical properties such as color tone, thus completing the present invention.

[0009] In other words, the present invention aims to advantageously solve the above problems, and the method for reusing resin molded articles of the present invention is characterized by comprising the steps of: crushing a resin molded article containing an alicyclic structure-containing polymer to obtain a molded article pulverized product; and dissolving the molded article pulverized product in a mixed solvent containing 80% to 98% by weight of cyclohexane and 2% to 20% by weight of a hydrocarbon or aromatic solvent with a freezing point of -40°C or lower, based on 100% by weight of the mixed solvent, to obtain a polymer solution. By crushing the molded article, the dissolution time can be shortened. By using a mixed solvent containing a solvent with a freezing point of -40°C or lower, solidification of the solvent and polymer solution (solution in which the molded article is dissolved in the mixed solvent) can be prevented regardless of the temperature environment, for example, in cold environments such as winter, resulting in a good state of dissolution of the polymer solution, which can further suppress appearance defects of the recycled product and improve physical properties such as color tone.

[0010] In the present invention, a method for recycling resin molded articles is preferably characterized by further including a step of sieving the molded article pulverized with a sieve with a diameter of φ3 mm or more and 15 mm or less between the step of pulverizing the resin molded article and the step of dissolving the molded article pulverized with a sieve with a diameter of φ3 mm or more and 15 mm or less. By sieving the molded article with a sieve with a diameter of φ3 mm or less than the above upper limit, the size of the molded article pulverized with a diameter of φ3 mm or less is reduced, which shortens the dissolution time and improves dissolution efficiency, reduces appearance defects in the recycled product and improves physical properties such as color tone, and contributes to shortening the process time. Furthermore, by setting the diameter of the sieve to be φ3 mm or more than the above lower limit, it is possible to suppress the decrease in recovery efficiency due to molded article pulverized with a diameter of φ3 mm or more and 15 mm or less between the step of pulverizing the resin molded article and the step of dissolving the molded article pulverized with a sieve with a diameter of φ3 mm or more and 15 mm or less.

[0011] Furthermore, in the method for reusing resin molded articles of the present invention, it is preferable that the boiling point of the solvent is 150°C or lower. By setting the boiling point of the solvent to below the above temperature, it is possible to lower the boiling point of the mixed solvent. Lowering the boiling point of the mixed solvent makes it possible to shorten the drying time when the mixed solvent is dried off from the polymer solution to recover the resin, suppress the deterioration of the resin due to high-temperature drying, suppress the residual solvent in the resin, and suppress the generation of smudges during pelletization (melt extrusion) due to residual solvent, thereby contributing to reducing appearance defects in the recycled product, improving physical properties such as color tone, and shortening the process time.

[0012] Furthermore, the present invention's method for reusing resin molded articles is preferably characterized by further comprising the step of adding an adsorbent to a molded article pulverization solution. By adding an adsorbent, foreign matter (e.g., soluble foreign matter such as altered antioxidants) in the polymer solution can be adsorbed and removed, which can help to further suppress appearance defects in the recycled product and improve physical properties such as color tone.

[0013] Furthermore, in the method for reusing resin molded articles of the present invention, the adsorbent is preferably acid clay, activated clay, activated alumina, or zeolite. These adsorbents can effectively adsorb soluble foreign substances such as altered antioxidants.

[0014] Furthermore, the present invention's method for reusing resin molded articles is preferably characterized by further comprising a step of filtering the polymer solution in solution state to remove foreign matter and adsorbents. Filtration in solution state (solution filtration) can remove insoluble foreign matter (e.g., additional materials other than alicyclic structure-containing polymers such as urethane), adsorbents, and soluble foreign matter adsorbed on the adsorbents (e.g., altered antioxidants), thereby reducing appearance defects in the recycled product and contributing to improved physical properties such as color tone.

[0015] Furthermore, in the method for reusing resin molded articles of the present invention, it is preferable that the ratio of the amount of molded article pulverized to the total amount of the mixed solvent and molded article pulverized in the polymer solution when filtering the solution is 10% by weight or more and 20% by weight or less. By having the ratio of the amount of molded article to the total amount of the mixed solvent and molded article (filtration concentration) be above the lower limit, it is possible to suppress the generation of eye deposits due to residual solvent during pelletization (melt extrusion) caused by an excess amount of solvent, thereby contributing to the suppression of a decrease in resin recovery efficiency and the deterioration of the equipment. By having the filtration concentration be below the upper limit, it is possible to eliminate the generation of foreign matter caused by the prolonged dissolution time and solution filtration time, as well as the increase in differential pressure during solution filtration, thereby further suppressing appearance defects in the recycled product, improving physical properties such as color tone, and contributing to a reduction in process time.

[0016] Furthermore, the present invention's method for reusing resin molded articles is preferably characterized by further comprising the steps of: removing a mixed solvent from a polymer solution to recover a resin containing an alicyclic structure polymer; melting the recovered resin; and filtering the molten resin in a molten state. Filtration in a molten state (molten filtration) can remove non-molten foreign matter (e.g., resin degradation components such as burnt components), thereby reducing appearance defects in the recycled product and contributing to improved physical properties such as color tone.

[0017] Furthermore, in the method for reusing resin molded articles of the present invention, it is preferable that the glass transition temperature of the alicyclic structure-containing polymer is 70°C or higher and 170°C or lower. When the glass transition temperature (Tg) is within this range, the moldability of the resin during remolding and the heat resistance of the molded article for reuse are well balanced, which is preferable.

[0018] Furthermore, in the method for reusing a resin molded article of the present invention, the alicyclic structure-containing polymer may be selected from the group consisting of norbornene-based polymers, monocyclic cycloolefin-based polymers, cyclic conjugated diene-based polymers, vinyl alicyclic hydrocarbon polymers, and hydrogenated products thereof, and the alicyclic structure-containing polymer may be an amorphous resin. The method of the present invention can be suitably applied to these polymer resins for suppressing the appearance defects of recycled products and improving physical properties such as color tone.

[0019] Furthermore, in the method for reusing a resin molded article of the present invention, the resin molded article as a raw material may have a urethane layer having a thickness of 100 nm or less. According to the method of the present invention, the urethane layer can be removed to a high degree as a foreign substance, so the method of the present invention can also be suitably applied to a polymer resin having a urethane layer as a raw material for suppressing the appearance defects of recycled products and improving physical properties such as color tone.

Effects of the Invention

[0020] According to the method for reusing a resin molded article of the present invention, a recycled resin molded article containing an alicyclic structure-containing polymer with suppressed appearance defects and improved physical properties such as color tone can be obtained.

Mode for Carrying Out the Invention

[0021] Hereinafter, embodiments of the present invention will be described in detail.

[0022] (Method for Reusing Resin Molded Article) The method for reusing a resin molded article of the present invention (hereinafter referred to as "the method of the present invention") is characterized by comprising: a step of pulverizing a resin molded article containing an alicyclic structure-containing polymer to obtain a pulverized molded article ("pulverization step"); and a step of dissolving the pulverized molded article in a mixed solvent to obtain a polymer solution ("dissolution step"), wherein the mixed solvent comprises 80 wt% to 98 wt% of cyclohexane based on 100 wt% of the mixed solvent, and 2 wt% to 20 wt% of a hydrocarbon-based or aromatic-based solvent having a freezing point of -40°C or lower. The method of the present invention may further comprise any one or more of the following steps: • Between the process of crushing the resin molded body and the process of dissolving the crushed molded body, there is a process of sieving the crushed molded body (sieving process); • A step of adding an adsorbent to the molded body pulverization dissolution system (adsorbent addition step); • A process of filtering the polymer solution in solution state to remove foreign matter and adsorbents (solution filtration process); • A step of adding an antioxidant to the filtered polymer solution (antioxidant addition step); • A process of removing the mixed solvent from the polymer solution to recover the resin containing the alicyclic structure polymer (solvent removal process); • A process of melting the resin recovered in the solvent removal process (melting process); • A process of filtering molten resin in its molten state (molten filtration process); • A process of pelletizing molten resin to obtain pelletized resin as a recycled product (pelletization process); and • A step of forming a resin molded article as a recycled product from a resin (e.g., pelletized resin, molten resin) or polymer solution obtained in any of the above steps (molded article forming step).

[0023] <Alicyclic structure-containing polymer> In the method of the present invention, the alicyclic structure-containing polymer that becomes a component of the resin molded article as a raw material and recycled product has an alicyclic structure in its main chain and / or side chains, and from the viewpoint of mechanical strength, heat resistance, etc., it is preferable that the polymer contains an alicyclic structure in its main chain.

[0024] Examples of alicyclic structures include saturated alicyclic hydrocarbon (cycloalkane) structures and unsaturated alicyclic hydrocarbon (cycloalkene) structures. From the viewpoint of mechanical strength and heat resistance, cycloalkane and cycloalkene structures are preferred, with cycloalkane structures being the most preferred. There are no particular restrictions on the number of carbon atoms constituting the alicyclic structure, but typically, when the number is in the range of 4 to 30, preferably 5 to 20, and more preferably 5 to 15, properties such as mechanical strength and heat resistance are well balanced and therefore preferable. The proportion of repeating units containing the alicyclic structure in the polymer resin having the alicyclic structure used in the present invention can be appropriately selected according to the intended use, but is preferably 30% by weight or more, more preferably 50% by weight or more, particularly preferably 70% by weight or more, and most preferably 90% by weight or more. When the proportion of repeating units having the alicyclic structure in the polymer having the alicyclic structure is within this range, it is preferable from the viewpoint of transparency and heat resistance of the resin molded article.

[0025] Polymeric resins having an alicyclic structure include, specifically, (1) norbornene polymers, (2) monocyclic olefin polymers, (3) cyclic conjugated diene polymers, (4) vinyl alicyclic hydrocarbon polymers, and hydrogenated versions thereof. Among these, norbornene polymers are more preferred from the viewpoint of transparency and moldability. Examples of norbornene polymers include ring-opening polymers of norbornene monomers, ring-opening copolymers of norbornene monomers with other monomers capable of ring-opening copolymerization, and their hydrogenated products, addition polymers of norbornene monomers, and addition copolymers of norbornene monomers with other monomers capable of ring-opening copolymerization. Among these, ring-opening (co)polymer hydrogenated products of norbornene monomers are most preferred from the viewpoint of transparency. The polymer having the above-mentioned alicyclic structure is selected from known polymers disclosed, for example, in Japanese Patent Application Publication No. 2002-321302.

[0026] The glass transition temperature (Tg) of the alicyclic structure-containing polymer can be appropriately selected depending on the purpose of reuse, but a higher Tg is preferable, for example, because it increases the heat resistance of the molded product used for reuse. For example, it may be 70°C or higher, preferably 100°C or higher, and more preferably 120°C or higher. Tg can be measured, for example, by the method described in the examples of this specification.

[0027] The melt index (MI) of a polymer resin molded article containing an alicyclic structure may be, for example, within ±20% of the center, preferably within ±15% of the center, and more preferably within ±10% of the center. When the MI is within this range, stable extruded and injection molded articles are obtained, which is preferable. The MI can be measured, for example, under conditions of 250-280°C and a load of 2.16 kgf.

[0028] <Resin molded product> Examples of molded products for reuse include: molded products for optical applications such as lenses, prisms, optical films, optical sheets, optical disc substrates, light guides, light guides, optical fibers, and mirrors; molded products for medical applications such as disposable syringes, drug vials, drug packaging films, test cells, test containers, infusion bags, and syringe rods; molded products for electrical or electronic applications such as wire sheathing, wafer shippers, capacitor films, circuit boards, connectors, sheets, films, plates, containers, and insulating materials; and plates, pipes, rods, bottles, building materials, and stationery. Molded products for reuse may also include, for example, waste materials from molded products, processing waste generated during the manufacture of molded products (e.g., film edges, die-cutting remnants), and used molded products. Molded products for reuse may be derived from synthesized resins (virgin materials) or from recycled resins (recycled products). If the molded body to be reused has a planar shape, the thickness of the molded body may be, for example, 30 μm or more, preferably 40 μm or more, more preferably 50 μm or more, or for example, 100 μm or less, preferably 90 μm or less, more preferably 80 μm or less.

[0029] The resin molded article used as a raw material may have portions formed of additional materials other than the alicyclic structure-containing polymer, in addition to portions formed of the alicyclic structure-containing polymer. Such additional materials may be in the form of layers (coatings, laminates). Such additional materials may be organic or inorganic. Examples of such additional materials include adhesives (e.g., polyurethane, acrylic resin, polyester) and colorants. If the molded article has a planar shape, such additional materials may be present on one side of the molded article or on both sides. Such additional materials may be in the form of layers, and the thickness of the layers may be, for example, 10 nm or more, preferably 20 nm or more, more preferably 30 nm or more, and for example, 100 nm or less, preferably 90 nm or less, more preferably 80 nm or less. According to the method of the present invention, such additional materials can be removed to a high extent as foreign matter, especially when a solution filtration step is performed. Therefore, the method of the present invention can be suitably applied to improve physical properties such as color tone and reduce appearance defects in recycled products, even when polymer resins having portions formed of additional materials are used as raw materials.

[0030] <Grinding process> The method of the present invention includes a step of crushing a resin molded body, which is used as a raw material, to obtain a molded body pulverized product. The resin molded body can be crushed using, for example, a pulverizer or a cutter. By crushing the resin molded body, the dissolution time of the resin molded body can be shortened and the dissolution efficiency can be improved. This contributes to reducing appearance defects in recycled products, improving physical properties such as color tone, and shortening the process time.

[0031] <Sieving process> The method of the present invention preferably further includes a step of sieving the molded material through a sieve of a predetermined pore size (φ) between the step of crushing the resin molded body and the step of dissolving the molded material. The predetermined pore size may be, for example, 3 mm or more, preferably 4 mm or more, more preferably 5 mm or more, and may also be, for example, 15 mm or less, preferably 12 mm or less, and more preferably 10 mm or less. By sieving the molded body with a sieve of a diameter less than or equal to the above upper limit, the size of the molded material to be dissolved is reduced, which shortens the dissolution time, improves dissolution efficiency, reduces appearance defects in the recycled product, improves physical properties such as color tone, and contributes to shortening the process time. Furthermore, by setting the sieve diameter to be greater than or equal to the above lower limit, it is possible to suppress the decrease in recovery efficiency due to molded material that does not pass through the sieve.

[0032] <Dissolution process> The method of the present invention includes a step of dissolving the molded article pulverized material in a solvent. By dissolving the molded article pulverized material in a solvent, it is possible to easily remove insoluble foreign matter (e.g., resin degradation components such as burn components, coatings such as urethane) from the molded article pulverized material (e.g., removal by solution filtration) and soluble foreign matter (e.g., altered antioxidants) (e.g., removal by adsorption). The solvent is a mixed solvent containing 80% to 98% by weight of cyclohexane and 2% to 20% by weight of a hydrocarbon or aromatic solvent with a freezing point of -40°C or lower, based on 100% by weight of the mixed solvent. The freezing point of the solvent is -40°C or lower. The freezing point of the solvent can be measured, for example, by reading the crystallization temperature using a differential scanning calorimeter. Alternatively, a solvent having the above freezing point may be appropriately selected from solvent compounds whose physical properties have been disclosed. By using a mixed solvent containing a solvent with a low freezing point, the solidification of the solvent and polymer solution can be prevented regardless of the temperature environment, for example, in cold environments such as winter. This improves the solubility of the polymer solution, further suppresses appearance defects in recycled products, and improves physical properties such as color.

[0033] The solvent is not particularly limited insofar as it achieves the objectives of the present invention, but examples include hydrocarbon solvents such as n-hexane (freezing point -95°C, boiling point 69°C), n-heptane (freezing point -91°C, boiling point 98.4°C), and methylcyclohexane (freezing point -126°C, boiling point 100°C), and aromatic solvents such as toluene (freezing point -93°C, boiling point 111°C), xylene (freezing point -50°C, boiling point 140°C), and trimethylbenzene (freezing point -44.8°C, boiling point 164.7°C). The solvent may be one type or a mixture of two or more types.

[0034] The solvent is further preferably 150°C or lower, more preferably 150°C or lower, and particularly preferably 140°C or lower, with a boiling point (boiling point at atmospheric pressure of approximately 101.3 kPa) of 150°C or lower. The boiling point of the solvent can be measured, for example, at the equilibrium reflux boiling point. Alternatively, a solvent having the above boiling point may be appropriately selected from solvent compounds whose physical properties have been disclosed. The lower the boiling point of the solvent, the higher the drying properties of the solvent, which shortens the drying time when the mixed solvent is dried off from the polymer solution to recover the resin, suppresses resin degradation due to high-temperature drying, suppresses solvent residue in the resin, and suppresses the generation of smudges during pelletization (melt extrusion) due to residual solvent. This contributes to reducing appearance defects in recycled products, improving physical properties such as color tone, and shortening process time.

[0035] Such solvents are not particularly limited insofar as they achieve the objectives of the present invention, but examples include hydrocarbon solvents such as n-hexane, n-heptane, and methylcyclohexane, and aromatic solvents such as toluene and xylene.

[0036] Typically, solvent compounds that are compatible with cyclohexane and are good solvents for alicyclic polymers are used as the solvent. The examples of solvents exemplified above all fall under this category of solvent compounds.

[0037] The solvent content in the mixed solvent is 2% by weight or more, preferably 3% by weight or more, and more preferably 5% by weight or more, based on 100% by weight of the mixed solvent. If the solvent content is too low, the solvent and polymer solution may solidify easily in cold environments such as winter, which can cause operational problems. In addition, pre-coating of the filter body in the container containing the polymer solution (fixing the filter body to the discharge hole at the bottom of the container by sedimentation) becomes difficult, and the polymer solution may flow out without foreign matter being removed by filtration. To prevent these problems, it is preferable that the solvent content is above the lower limit mentioned above. The solvent content in the mixed solvent is 20% by weight or less, preferably 15% by weight or less, and more preferably 10% by weight or less, based on 100% by weight of the mixed solvent. If the solvent content is too high, resin components may easily precipitate from the polymer solution, which can reduce the recovery efficiency of recycled resin products or cause operational problems. To prevent these problems, it is preferable that the solvent content is below the upper limit mentioned above.

[0038] The cyclohexane content in the mixed solvent may be the entire amount remaining after removing the solvent from the mixed solvent. The cyclohexane content in the mixed solvent may be 80% by weight or more, preferably 85% by weight or more, and more preferably 90% by weight or more, based on 100% by weight of the mixed solvent. The cyclohexane content in the mixed solvent may be 98% by weight or less, preferably 97% by weight or less, and more preferably 95% by weight or less, based on 100% by weight of the mixed solvent.

[0039] The amount of molded body pulverized material added (the ratio of the amount of molded body pulverized material to the total amount of the mixed solvent and the molded body pulverized material) is not particularly limited as long as the method of the present invention can be carried out, but may be, for example, 10% by weight or more, preferably 11% by weight or more, more preferably 12% by weight or more, and may also be, for example, 20% by weight or less, preferably 19% by weight or less, more preferably 18% by weight or less. If the amount of molded body added is too little, the amount of solvent will be excessive, and even after solvent removal, some solvent will remain, causing eye residue to form due to the remaining solvent during pelletization (melt extrusion), causing resin to adhere to the melt extrusion outlet and deteriorate due to heat, resulting in foreign matter and strand instability. To prevent these problems, it is preferable that the amount of molded body added is above the lower limit. If the amount of molded body added is too much, the dissolution time and solution filtration time will be prolonged, and foreign matter may be generated due to the increase in differential pressure during solution filtration. To prevent these problems, it is preferable that the amount of molded body added is below the upper limit.

[0040] The temperature at which the molded article is dissolved in the solvent is not particularly limited as long as the molded article can be dissolved, but may be, for example, 50°C or higher, preferably 55°C or higher, more preferably 60°C or higher, and may be, for example, 80°C or lower, preferably 75°C or lower, more preferably 70°C or lower.

[0041] <Adsorbent addition process> The method of the present invention preferably further includes a step of adding an adsorbent to the molded body pulverization solution system. "Adding an adsorbent to the molded body pulverization solution system" means that the adsorbent is added so as to be in contact with the polymer solution. For example, it may be added to the polymer solution, to the mixed solvent used for dissolving the molded body pulverization, to the mixed solvent together with the molded body pulverization, or to be added to the container used for dissolution beforehand. The addition of an adsorbent allows for the adsorption and removal of foreign matter in the polymer solution (e.g., soluble foreign matter such as altered antioxidants), thereby reducing appearance defects in the recycled product and contributing to improved physical properties such as color tone. Examples of such adsorbents include acid clay, activated clay, activated alumina, and zeolite. These adsorbents can effectively adsorb soluble foreign matter such as altered antioxidants. The amount of adsorbent may be, for example, 2.0 parts by weight or more, preferably 2.5 parts by weight or more, more preferably 3.0 parts by weight or more, per 100 parts by weight of the mixed solvent, or for example, 5.0 parts by weight or less, preferably 4.5 parts by weight or less, more preferably 4.0 parts by weight or less.

[0042] <Solution filtration process> The method of the present invention preferably further includes a step of filtering the polymer solution in solution to remove foreign matter and adsorbents. This step allows for the removal of insoluble foreign matter (e.g., additional materials other than alicyclic structure-containing polymers such as urethane), adsorbents, and soluble foreign matter adsorbed on the adsorbents (e.g., altered antioxidants) by filtration in solution (solution filtration), thereby contributing to the reduction of appearance defects in recycled products and improving physical properties such as color tone. Solution filtration may be performed using a filter aid as the filter bed. Examples of filter aids include diatomaceous earth (e.g., trade name "Radiolite") and perlite (e.g., trade name "Topco").

[0043] The ratio of the amount of molded body in the solution to the total amount of the mixed solvent and the molded body in the solution during solution filtration (filtration concentration) does not have to be adjusted from the amount at the time of molded body dissolution, but may be adjusted by dilution with the mixed solvent, for example, it may be 10% by weight or more, preferably 11% by weight or more, more preferably 12% by weight or more, and may also be 20% by weight or less, preferably 19% by weight or less, more preferably 18% by weight or less. If the filtration concentration is too low, the amount of solvent will be excessive, and even after solvent removal, some solvent will remain, causing residue to form due to the remaining solvent during pelletization (melt extrusion), causing resin to adhere to the melt extrusion outlet, leading to thermal degradation and the formation of foreign matter, as well as making the strand unstable. To prevent these problems, it is preferable that the filtration concentration be above the lower limit. If the filtration concentration is too high, the dissolution time and solution filtration time will be prolonged, and foreign matter may be generated due to the increase in differential pressure during solution filtration. To prevent these problems, it is preferable that the filtration concentration be below the upper limit.

[0044] Solution filtration may be performed, for example, by pressure filtration or vacuum filtration. The pressure for pressure filtration may be, for example, 0.2 MPa or more, preferably 0.24 MPa or more, and may be, for example, 1.0 MPa or less, preferably 0.8 MPa or less, where the differential pressure between the inlet and outlet of the filter is 0.2 MPa or more, preferably 0.4 MPa or more, where the differential pressure between the inlet and outlet of the filter is 0.2 MPa or more, preferably 0.4 MPa or more. Note that the differential pressure refers to the differential pressure at the highest differential pressure during filtration. If the differential pressure for solution filtration is above the lower limit above, the solution filtration rate can be improved while improving the rate of removal of foreign matter from the solution. If the differential pressure for solution filtration is below the upper limit above, the load on the equipment can be reduced, and the lifespan of the equipment can be improved. The temperature at which solution filtration is performed is not particularly limited as long as the polymer solution can be filtered, but may be, for example, 50°C or more, preferably 55°C or more, more preferably 60°C or more, and may be, for example, 80°C or less, preferably 75°C or less, more preferably 70°C or less.

[0045] <Antioxidant addition process> The method of the present invention preferably further includes the step of adding an antioxidant to the filtered polymer solution. Typically, resin molded articles that are reused contain antioxidants, and at least a portion of these antioxidants may deteriorate during use of the resin molded article. Therefore, this step can replenish the antioxidants that have been lost due to deterioration. As the antioxidant, general antioxidants for polymer resins containing alicyclic structures can be used, such as phenolic antioxidants, phosphorus-based antioxidants, and sulfur-based antioxidants. Among these, phenolic antioxidants are preferred, and alkyl-substituted phenolic antioxidants are particularly preferred.

[0046] As phenolic antioxidants, various conventionally known substances may be used, for example, acrylate compounds described in Japanese Patent Publication No. 63-179953 and Japanese Patent Publication No. 1-168643, such as 2-t-butyl-6-(3-t-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenyl acrylate and 2,4-di-t-amyl-6-(1-(3,5-di-t-amyl-2-hydroxyphenyl)ethyl)phenyl acrylate; octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, 2 ,2'-methylene-bis(4-methyl-6-t-butylphenol), 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane, 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene, tetrakis(methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenylpropionate)methane [i.e., pentaerythrimethyl-tetrakis(3-(3,5-di-t-butyl-4-hydroxyphenylpropionate)], triethylene glycol Examples include alkyl-substituted phenolic compounds such as bis(3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionate); and triazine group-containing phenolic compounds such as 6-(4-hydroxy-3,5-di-t-butylanilino)-2,4-bisoctylthio-1,3,5-triazine, 4-bisoctylthio-1,3,5-triazine, and 2-octylthio-4,6-bis-(3,5-di-t-butyl-4-oxyanilino)-1,3,5-triazine.

[0047] As phosphorus-based antioxidants, various substances commonly used in the general resin industry may be used, for example monophosphite compounds such as triphenyl phosphite, diphenylisodecyl phosphite, phenyl diisodecyl phosphite, tris(nonylphenyl) phosphite, tris(dinonylphenyl) phosphite, tris(2,4-di-t-butylphenyl) phosphite, and 10-(3,5-di-t-butyl-4-hydroxybenzyl)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide; and diphosphite compounds such as 4,4'-butylidene-bis(3-methyl-6-t-butylphenyl-di-tridecyl phosphite) and 4,4'-isopropylidene-bis(phenyl-di-alkyl(C12~C15) phosphite). Among these, monophosphite compounds are preferred, with tris(nonylphenyl)phosphite, tris(dinonylphenyl)phosphite, and tris(2,4-di-t-butylphenyl)phosphite being particularly preferred.

[0048] Examples of sulfur-based antioxidants include dilauryl 3,3-thiodipropionate, dimyristyl 3,3'-thiodipropionate, distearyl 3,3-thiodipropionate, laurylstearyl 3,3-thiodipropionate, pentaerythritol-tetrakis-(β-lauryl-thio-propionate, 3,9-bis(2-dodecylthioethyl)-2,4,8,10-tetraoxaspiro[5,5]undecane.

[0049] These antioxidants may be used individually or in combination of two or more. The amount of antioxidants added is not particularly limited as long as it does not impair the properties of the recycled product, but the total amount including the antioxidants contained in the resin molded article before recycling may be, for example, 0.2 parts by weight or more, preferably 0.3 parts by weight or more, more preferably 0.4 parts by weight or more, per 100 parts by weight of the polymer component, or for example, 1.0 part by weight or less, preferably 0.8 parts by weight or less, more preferably 0.7 parts by weight or less.

[0050] <Solvent removal process> The method of the present invention preferably further includes a step of removing a mixed solvent from the polymer solution to recover a resin containing an alicyclic structure polymer. The removal of the mixed solvent can be carried out, for example, by drying the mixed solvent. Drying of the mixed solvent may be carried out, for example, by heating drying, vacuum drying, or heated vacuum drying. The temperature at which heating drying or heated vacuum drying is carried out is not particularly limited as long as the mixed solvent can be removed, but may be, for example, 250°C or higher, preferably 260°C or higher, more preferably 270°C or higher, and may be, for example, 320°C or lower, preferably 310°C or lower, more preferably 300°C or lower. The pressure at which vacuum drying or heated vacuum drying is carried out is a pressure lower than atmospheric pressure, for example, -90kPa or lower, preferably -95kPa or lower, more preferably -100kPa or lower. When heating drying or heated vacuum drying is carried out, the resin may be recovered in a molten state. The recovered resin may be used as is as recycled resin for molding recycled resin molded articles, but it is preferable to continue using it in a melting step or a melt filtration step.

[0051] <Melting process> The method of the present invention preferably further includes a step of melting the resin containing the alicyclic structure-containing polymer recovered in the solvent removal step. Melting can be carried out by heating the recovered resin. The melting temperature can be appropriately determined depending on the type of alicyclic structure-containing polymer, but may be, for example, 250°C or higher, preferably 260°C or higher, more preferably 270°C or higher, or for example, 320°C or lower, preferably 310°C or lower, more preferably 300°C or lower. Note that if the resin becomes molten in the solvent removal step, for example by heating and drying or heating and vacuum drying, the solvent removal step will also serve as the melting step. The molten resin obtained in the melting step may be used as recycled resin to mold recycled resin articles, but it is preferable to continue using it in a melt filtration step or a pelletizing step.

[0052] <Melting filtration process> The method of the present invention preferably further includes a step of filtering a resin containing a molten alicyclic structure polymer in a molten state. The molten resin may be obtained in the solvent removal step (when the resin is obtained in a molten state) or the melting step. For example, a leaf disc type filter or a candle type filter may be used for melt filtration. The mesh diameter of the filter may be, for example, 40 μm or less, preferably 20 μm or less, and preferably 10 μm or less. The differential pressure of melt filtration may be, for example, 7 MPa or less, preferably 5 MPa or less, and more preferably 3 MPa or less. Note that the differential pressure refers to the differential pressure at the highest differential pressure during filtration. By performing the melt filtration step, non-molten foreign matter (e.g., resin degradation components such as burn components) can be removed, which can help to further suppress appearance defects in the recycled product and improve physical properties such as color tone. If the differential pressure of melt filtration is below the above upper limit, the load on the equipment can be reduced and the lifespan of the equipment can be improved. Also, when both the solution filtration step and the melt filtration step are performed, it is preferable that the differential pressure of melt filtration (B) is greater than the differential pressure of solution filtration (A). In this case, the difference (BA) between the differential pressure (A) of solution filtration and the differential pressure (B) of melt filtration may be, for example, 6.5 MPa or less, preferably 6 MPa or less, and more preferably 5 MPa or less, as an upper limit. Also, the difference (BA) between the differential pressure (A) of solution filtration and the differential pressure (B) of melt filtration may be, for example, 0.3 MPa or more, preferably 0.5 MPa or more, and more preferably 1.0 MPa or more, as a lower limit. If the above differential pressure difference (BA) is above the lower limit, the foreign matter removal rate and solution filtration speed during solution filtration can be improved, while the foreign matter removal rate and melt filtration speed during melt filtration can also be further improved. If the above differential pressure difference (BA) is below the upper limit, the load on the equipment can be reduced, and the lifespan of the equipment can be improved.

[0053] <Pelletization Process> The method of the present invention preferably further includes a step of pelletizing a resin containing a molten alicyclic structure to obtain pelletized resin as a recycled product. The molten resin may be obtained in a solvent removal step (when the resin is obtained in a molten state), a melting step, or a melt filtration step. The method for obtaining pelletized resin (recycled pellets) is not particularly limited, and any known method can be used. For example, one method is to heat and melt the above molded body, extrude the resin in a strand (rod) shape from a strand die in a molten state, cool it, and then cut it with a strand cutter to pelletize it.

[0054] The melting temperature of the molded body is preferably in the range of Tg+60(°C) to Tg+180(°C), and more preferably in the range of Tg+90(°C) to Tg+160(°C), where Tg(°C) is the glass transition temperature of the polymer resin having an alicyclic structure. If the temperature is too low, the viscosity will be high, and the resulting recycled pellets may be non-uniform. If the temperature is too high, the resin and compounding agents will deteriorate, and the melt flow rate and yellowness of the resulting recycled pellets may change significantly from the resin molded body before reuse.

[0055] Strand cutting methods include, for example, the "cold cut method," which involves water-cooling and solidifying the rod-shaped strand extruded from the die hole before cutting, and the "hot cut method," which cuts the strand immediately after it is extruded from the die hole; both methods can be applied.

[0056] The shape of the recycled pellets is usually circular or elliptical in cross-section (the plane perpendicular to the strand discharge direction), but can be formed into any shape by the molding die hole shape. The average diameter of the pellet cross-section is usually 0.1 to 10 mm, preferably 0.5 to 5 mm, and more preferably 1 to 4 mm. The length of the pellets (length in the strand discharge direction) can be arbitrarily changed by the strand cutting speed, but is usually 1 to 10 mm, preferably 2 to 8 mm, and more preferably 2 to 6 mm.

[0057] <Molded object forming process> The method of the present invention preferably further includes a step of forming a resin molded article containing an alicyclic structure-containing polymer as a recycled product from a resin (e.g., pelletized resin, molten resin) or polymer solution containing an alicyclic structure-containing polymer obtained in any of the above steps. Examples of resins obtained in any of the above steps include pelletized resin obtained in a pelletizing step, solvent removal step (when the resin is obtained in a molten state), melting step, or molten resin obtained in a melt filtration step. Examples of polymer solutions obtained in any of the above steps include polymer solutions obtained in a dissolution step (when an adsorbent addition step is not performed), solution filtration step, or antioxidant addition step. The resin molded article may be formed, for example, by melt extrusion molding of a resin (e.g., pelletized resin) or by melting the resin and pouring it into a molding machine (e.g., mold), by extrusion molding of a molten resin or by pouring a molten resin into a molding machine (e.g., mold), or by pouring a polymer solution into a molding machine (e.g., mold) and then removing the solvent (e.g., drying).

[0058] When forming a film as a recycled molded body, the recycled molded body formation process may be carried out by forming recycled pellets into a film.

[0059] The method for forming the recycled pellets into a film is not limited, and for example, either a melt molding method or a solution casting method may be used. Examples of melt molding methods include extrusion molding by melt extrusion, as well as press molding, inflation molding, injection molding, blow molding, and stretch molding. Among these methods, extrusion molding by melt extrusion is preferred from the viewpoint of obtaining a film with excellent mechanical strength and surface accuracy. According to the manufacturing method of the present invention, even in extrusion molding which is subjected to a thermal history due to heating and melting, the generation of foreign matter is suppressed, and an optical film with a low foreign matter content can be obtained.

[0060] Extrusion molding is a method of continuously obtaining molded products in the shape of a film by heating and melting resin in an extruder and then extruding it through a flat die. The extruder heats and kneads the resin and extrudes the molten material in the shape of a film from the die at a constant extrusion rate. The extruded molten material is taken up by rolls rotating at a constant speed and cooled to form the product. The temperature and layout of the rolls are not particularly limited. Examples of flat dies include T-dies, coat hanger dies, and fishtail dies, depending on the structure of the resin distribution channel.

[0061] The thickness of the resulting optical film can be adjusted by adjusting the extrusion resin temperature and pressure, or by fine-tuning the gap between the lip portions through which the molten resin is extruded. The temperature of the extruded resin is typically 80°C to 180°C higher than the glass transition temperature of the recycled pellets. The gap between the lip portions can be adjusted using a choke bar and a choke bar adjustment bolt. Furthermore, it is preferable to adjust the temperature of the heat sleeve and use the thermal expansion or contraction of the heat sleeve to fine-tune the gap between the lip portions. The temperature of the heat sleeve can be adjusted by known process control, such as PID control.

[0062] The thickness of the resulting optical film varies depending on the type and application of the optical film, but is usually 10 μm or more, preferably 15 μm or more, more preferably 20 μm or more, and usually 700 μm or less, preferably 500 μm or less, more preferably 300 μm or less.

[0063] The optical film obtained by the manufacturing method of the present invention may be a stretched optical film obtained by further stretching the optical film obtained above. Known stretching methods such as uniaxial stretching, biaxial stretching, or oblique stretching can be appropriately employed as methods for stretching the film. The stretching method is not particularly limited, but examples include roll-type and float-type longitudinal stretching, tenter-type transverse uniaxial stretching, simultaneous biaxial stretching, and oblique stretching. The temperature when stretching the film before stretching is preferably in the range of Tg+2°C to Tg+30°C, more preferably Tg+5°C to Tg+25°C, where Tg is the glass transition temperature of the recycled pellet. The stretching ratio is usually 1.01 to 30 times, preferably 1.01 to 10 times, more preferably 1.01 to 5 times.

[0064] The optical film obtained by the manufacturing method of the present invention has a low foreign matter content and can therefore be suitably used in the manufacture of optical components in display devices such as liquid crystal displays and electroluminescent displays. The optical film can be used in display devices and optical components as a phase difference film, a protective film for polarizing plates, a polarizing film, a brightness-enhancing film, a light-diffusing film, a light-gathering film, a reflective film, and the like. [Examples]

[0065] The present invention will be described in more detail below with reference to examples and comparative examples. The present invention is not limited to these examples. In the following examples and comparative examples, parts and percentages are by weight unless otherwise specified. In the examples and comparative examples, each measurement item and evaluation item was measured or evaluated using the following methods.

[0066] <Molecular weight (Mw, Mn)> The weight-average molecular weight (Mw) and number-average molecular weight (Mn) were measured at 40°C as standard polyisoprene equivalent values ​​using gel permeation chromatography (GPC) with cyclohexane as the eluent. A Tosoh HLC8120GPC was used as the measurement device. Ten samples of standard polyisoprene manufactured by Tosoh Corporation were used, with Mw values ​​of 602, 1390, 3920, 8050, 13800, 22700, 58800, 71300, 109000, and 280000. The sample was prepared by heating and dissolving the sample in cyclohexane at 40°C to a sample concentration of 4 mg / mL. The measurements were performed using three columns manufactured by Tosoh Corporation: TSKgelG5000HXL, TSKgelG4000HXL, and TSKgelG2000HXL, connected in series. The conditions were a flow rate of 1.0 mL / min, a sample injection volume of 100 μmL, and a column temperature of 40°C.

[0067] <Hydrogenation rate> Using a mixed solution of deuterated chloroform and carbon tetrachloride (1 / 1 by weight ratio) as the solvent, 1 The measurement was performed using H-NMR spectroscopy.

[0068] <Glass transition temperature (Tg)> Measurements were taken using a differential scanning calorimetry analyzer, in accordance with JIS K6911.

[0069] <Dissolution time> (Longer dissolution times result in a poor production cycle.) The time it takes for 100g of the sample to dissolve after grinding. Check if the specified concentration is achieved with the given solvent composition and AG stirring at 100 revolutions per minute. Samples were taken at each time point, dried in a vacuum drying oven at 120°C for 12 hours, and the dissolved concentration was checked. ◎: Less than 0.5 hours ○: 0.5 hours to less than 1.0 hour △: More than 1 hour

[0070] <Foreign matter (300μm or less)> (If the quantity is too large, it cannot be used as a product.) The number of foreign objects in 500g of pellets was confirmed visually and using a microscope (KEYENCE VHX-2000). The size of the foreign object is determined by measuring its longest side. ◎:0 pieces 〇: 2 or less ×: 3 or more

[0071] <Eye discharge> (High values ​​make the product unusable and are one of the causes of foreign matter contamination.) The percentage of die holes with 0.3 mm or more of eye discharge attached (number of attached holes relative to the total number of holes) was visually confirmed using calipers after 4 hours. The amount of resin released from one hole is 150-200 kg in 4 hours (based on 40 holes). ◎: Less than 10% ○: 10% or more, less than 30% ×: 30% or more

[0072] <Yellowness (ΔYi)> (High values ​​result in a strong yellow color, making the product unusable, and indicating oxidative degradation of the resin.) Pellets were injection molded using a Nissei Plastic Industrial Co., Ltd. NS20-2A type mold at a cylinder temperature of 200-300°C to produce 3mm thick plates. The yellowness (hereinafter referred to as ΔYi) of the plate was measured using a spectrophotometer capable of measuring the XYZ color system (manufactured by Nippon Denshoku Industries, model: SE2000). ◎: Less than 0.5 ○: 0.5 or higher and less than 0.7 ×: 0.7 or higher

[0073] <Method for evaluating cosmetic defects> (If the quantity is too large, it cannot be used as a product.) Cosmetic defects were observed using a computer-controlled epifluorescence microscope (Olympus BX61-FL) with BV excitation (435 nm) and a magnification of 200x. The film was placed under the microscope, and the number of fluorescent foreign objects within a 1 cm x 1 cm field of view was counted. 2 The number of foreign objects per unit was calculated (volume: 0.4 cm³). 3 Furthermore, the foreign objects were also classified by size and evaluated according to the following criteria. A: The number of foreign objects larger than 3 μm is 10 or less. B: The number of foreign objects with a size of 3 μm or larger is between 11 and 29. C: The number of foreign matters with a size of 3 µm or more is 30 or more and 99 or less. D: The number of foreign matters with a size of 3 µm or more is 100 or more.

[0074] [Production Example 1. Production of raw material ring-opened molded product] <A-1. Preparation of ring-opened alicyclic structure-containing polymer resin for raw material> <<A-1-1. Ring-opening polymerization>> Into a reactor purged with nitrogen, tricyclo[4.3.0.1 2,5 deca-3-ene (hereinafter referred to as "DCP") and tetracyclo[4.4.0.1 2,5 .1 7,10 dodeca-3-ene (hereinafter referred to as "TCD") and tetracyclo[9.2.1.0 2,10 .0 3,8 tetradeca-3,5,7,12-tetraene (hereinafter referred to as "MTF") (weight ratio: 52 / 38 / 10) in an amount of 7 parts (1% by weight based on the total amount of monomers used for polymerization) and 1600 parts of cyclohexane were added, followed by addition of 0.55 parts of tri-i-butylaluminum, 0.21 parts of isobutyl alcohol, 0.84 parts of diisopropyl ether as a reaction regulator, and 3.24 parts of 1-hexene as a molecular weight regulator. 24.1 parts of a 0.65% tungsten hexachloride solution dissolved in cyclohexane was added thereto, and the mixture was stirred at 55°C for 10 minutes. Then, while maintaining the reaction system at 55°C, 693 parts of the mixture of DCP, TCD and MTF (weight ratio: 52 / 38 / 10) and 48.9 parts of a 0.65% tungsten hexachloride solution dissolved in cyclohexane were each continuously added dropwise into the system over 150 minutes. Thereafter, the reaction was continued for 30 minutes to complete the polymerization. After completion of the polymerization, the polymerization conversion of the monomers measured by gas chromatography was 100% at the completion of the polymerization.

[0075] <<A-1-2. Hydrogenation>> The obtained ring-opening polymerization reaction solution was transferred to a pressure-resistant hydrogenation reactor, and 1.4 parts of diatomaceous earth-supported nickel catalyst (manufactured by Clariant Catalysts, product name "T8400RL", nickel loading rate 57%) and 167 parts of cyclohexane were added, and the reaction was allowed to proceed at 180°C under a hydrogen pressure of 4.6 MPa for 6 hours. This reaction solution was subjected to pressure filtration using Radiolite #500 as a filter bed at a pressure of 0.25 MPa (manufactured by Ishikawajima-Harima Heavy Industries Co., Ltd., product name "Funda Filter") to remove the hydrogenation catalyst, whereby a colorless and transparent solution was obtained. Next, 0.5 parts of antioxidant, pentaerythritol tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate] (manufactured by Ciba Specialty Chemicals, product name "Irganox 1010"), per 100 parts of the hydrogenated product was added to and dissolved in the obtained solution. Subsequently, filtration was sequentially performed with a Zeta Plus Filter 30H (manufactured by Cuno Filter, pore diameter 0.5 to 1 µm), and then further filtration was performed with another metal fiber filter (pore diameter 0.4 µm, manufactured by Nichidai Co., Ltd.) to remove fine solid content. The hydrogen conversion rate of the hydrogenated ring-opened polymer was 99.9%. Next, the above solution was subjected to removal of cyclohexane as the solvent and other volatile components from the solution using a cylindrical concentrating dryer (manufactured by Hitachi, Ltd.) at a temperature of 270°C and a pressure of 1 kPa or less. The molten polymer was passed through a polymer filter (manufactured by Fuji Filter Co., Ltd.) at 270°C, extruded in a molten state into a strand form from a die directly connected to the concentrator, and after cooling, pellet A of the hydrogenated ring-opened polymer was obtained as a raw material ring-opened alicyclic structure-containing polymer resin (ring-opened polymer resin). The weight average molecular weight (Mw) of the hydrogenated ring-opened polymer constituting pellet A was 38,000, the molecular weight distribution (Mw / Mn) was 2.5, the Tg was 129°C, and ΔYi was 0.35. Furthermore, since the polymerization conversion rate during the synthesis of the ring-opened polymer is 100%, and the hydrogen conversion rate is also as high as 99.9%, it is estimated that the DCP-derived structural unit (DCP unit), TCD-derived structural unit (TCD unit), and MTF-derived structural unit (MTF unit) in the hydrogenated ring-opened polymer are equal to the usage amounts of the monomers used in the production of the ring-opened polymer.

[0076] <A-2. Preparation of raw material base film> <<A-2-1. Production of unstretched film for raw material>> The obtained pellet A was dried at 70°C for 2 hours using a hot air dryer with circulated air to remove moisture, then melt extrusion was performed using a T-die type film melt extrusion molding machine (T-die width 500 mm) equipped with a resin melt kneader having a 65 mmφ screw, in a clean room of class 10,000 or lower, under molding conditions of a molten resin temperature of 229°C and a T-die temperature of 229°C, to extrude and mold a sheet of unstretched film A having a thickness of 100 μm and a width of 500 mm. The obtained sheet was wound onto a roll and recovered.

[0077] <<A-2-2. Raw material base film (Production of stretched film)>> The wound and recovered sheet, together with the roll, was attached to a stretching apparatus installed in the same clean room as described above, heated to 139°C (Tg+10°C) by heating rolls, then passed through a first roll and a second roll having different rotation speeds in order, while the sheet was uniaxially stretched in the extrusion direction at a stretching ratio of 2.0 times and a stretching speed (pulling speed) of 15 mm / sec, to obtain stretched film A as a raw material base film.

[0078] <A-3. Production of polyurethane resin composition for coating> 100 parts (as polyurethane) of an aqueous dispersion of polyether-based polyurethane ("Superflex 150HS" manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), 15 parts of an epoxy compound as a crosslinking agent ("Denacol EX313" manufactured by Nagase ChemteX Corporation), 8 parts (as silica particles) of an aqueous dispersion of silica particles as a lubricant ("Snowtex MP1040" manufactured by Nissan Chemical Corporation; average particle diameter 120 nm), 8 parts (as silica particles) of an aqueous dispersion of silica particles ("Snowtex XL" manufactured by Nissan Chemical Corporation; average particle diameter 50 nm), 0.5 wt% of an acetylene-based surfactant as a wetting agent ("Surfynol 440" manufactured by Air Products and Chemicals, Inc.) relative to the total solid content, and water were blended to obtain a liquid resin composition 1 (polyurethane resin composition for coating) having a solid content concentration of 2%.

[0079] <A-4. Production of raw material molded article (multilayer film)> Using a corona treatment device (manufactured by Kasuga Electric Co., Ltd.), the surface of the stretched film A (base film) obtained in A-2-2 above was subjected to electrical discharge treatment under the conditions of output 300W, electrode length 240mm, work electrode spacing 3.0mm, and transport speed 4m / min. The liquid resin composition 1 was applied to the electrical discharge treated surface of the stretched film A using a roll coater to a dry thickness of 0.1μm. Subsequently, it was heated at a temperature of 130°C for 60 seconds to form an easy-adhesion layer (polyurethane layer) on the base film. This yielded a multilayer film comprising the base film and the easy-adhesion layer as a raw material molded body. The ends of the multilayer film were separated by slitting, and the obtained ends were wound onto a roll and recovered.

[0080] [Example 1. Reuse of molded products] <1-1. Recovery of ring-opening polymer resin from raw material molded products> The ends of the rolled-up film were crushed using a crusher, and the film fragments were collected by passing them through a 5mm perforated sieve (punching plate). The fragments were placed on a belt conveyor and sent to a dissolution tank, where 17.6 parts of the film fragments (15% concentration) were added to 100 parts of a mixed solvent consisting of 93% cyclohexane (freezing point 6.5°C, boiling point 81.4°C) and 7% methylcyclohexane (freezing point -126°C, boiling point 100°C). 0.53 parts of acid clay (manufactured by Mizusawa Chemical Industry Co., Ltd., product name "Mizuka Ace #20") were added as an adsorbent, and the mixture was stirred at 70°C for more than 2 hours. This solution was subjected to pressure filtration at a pressure of 0.25 MPa (outlet open to the atmosphere) using Radiolite #300 as a filter bed (manufactured by Ishikawajima-Harima Heavy Industries, product name "Funda Filter") to remove the adsorbent and obtain a colorless, transparent solution. Next, 0.5 parts of the antioxidant: pentaerythritol tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate] (manufactured by Ciba Specialty Chemicals, product name "Irganox 1010") were dissolved in 100 parts of the aforementioned film pulverized material. Then, the solution was sequentially filtered through Zeter Plus Filter 30H (manufactured by Quno Filters, pore size 0.5~1 μm) and further filtered through another metal fiber filter (pore size 0.4 μm, manufactured by Nichidai) to remove minute solid particles. Next, the above solution was subjected to a cylindrical concentrator and dryer (manufactured by Hitachi, Ltd.) at a temperature of 270°C and a pressure of 1 kPa or less to remove the solvent cyclohexane and other volatile components from the solution. The molten polymer was then passed through a polymer filter (manufactured by Fuji Filter) at 270°C with an inlet pressure of 5.2 MPa and an outlet pressure of 2.0 MPa, and extruded in a strand-like state from a die directly connected to the concentrator, thereby performing melt filtration. After cooling, ring-opening polymer hydrogenated pellets B were obtained as a regenerated alicyclic structure-containing polymer resin. The dissolution time of the film pulverized material, the degree of deposits (eye residue) generated at the die exit after extrusion molding, the degree of foreign matter generation in pellet B, and the ΔYi of pellet B were evaluated.

[0081] <1-2. Preparation of recycled unstretched film> The obtained pellets B were dried at 70°C for 2 hours in a hot air dryer with circulating air to remove moisture. Then, an unstretched film B with a thickness of 100 μm and a width of 500 mm was extruded using a T-die type film melt extrusion molding machine (T-die width 500 mm) equipped with a resin melt kneader with a 65 mmφ screw, in a cleanroom of class 10,000 or less, under molding conditions of a molten resin temperature of 229°C and a T-die temperature of 229°C. The obtained sheet was wound onto a roll and recovered.

[0082] <1-3. Creation of recycled stretched film> The above-mentioned sheet, which was wound and recovered, was attached roll by roll to a stretching device installed in the same cleanroom as above. After heating to 139°C (Tg + 10°C) with a heating roll, the sheet was uniaxially stretched at a stretching speed (tensile speed) of 15 mm / second in the extrusion direction at a stretching ratio of 2.0 times, while passing through a first roll and then a second roll with different rotation speeds, thereby obtaining stretched film B as a recycled stretched film (recycled molded body). The appearance defects of the obtained stretched film B were evaluated.

[0083] [Example 2] The procedure was the same as in Example 1, except that when dissolving the film pulverized material in the mixed solvent, 23.5 parts of the film pulverized material (19% concentration) were added to 100 parts of the mixed solvent.

[0084] [Examples 3, 4, 6] The procedure was carried out in the same manner as in Example 1, except that a mixed solvent of 93% cyclohexane and 7% toluene (freezing point -93°C, boiling point 111°C) (Example 3), a mixed solvent of 98% cyclohexane and 2% methylcyclohexane (Example 4), or a mixed solvent of 81% cyclohexane and 19% methylcyclohexane (Example 6) was used as the mixed solvent.

[0085] [Example 5] The procedure was the same as in Example 1, except that a base film without an easy-adhesion layer (polyurethane layer) was used as the raw material molded body.

[0086] [Example 7] The procedure was the same as in Example 1, except that melt filtration was not performed.

[0087] [Examples 8 and 9] The procedure was carried out in the same manner as in Example 1, except that activated clay (Mizusawa Chemical Industries, Ltd., product name "Galleon Earth", Example 8) or activated alumina (Sumitomo Alchem ​​Co., Ltd., product name "A-11", Example 9) was used as the adsorbent.

[0088] [Example 10] The procedure was the same as in Example 1, except that the film shreds were collected by passing them through a punching plate with 20 mm holes.

[0089] [Example 11] The process for producing the raw material molded product was carried out in the same manner as in Example 1, except that copolymer B (raw material addition type alicyclic structure-containing polymer resin) prepared in Production Example 2 below was used instead of the ring-opening polymer resin for raw materials.

[0090] [Manufacturing Example 2. Manufacturing of Additive-Type Molded Products] <<Preparation of a copolymer of cyclic olefin and chain olefin (Copolymer B)>> Into a reaction vessel charged with 258 liters of cyclohexane, 120 kg of norbornene was added at room temperature under a nitrogen stream, and the mixture was stirred for 5 minutes. Triisobutylaluminum was further added so that the concentration in the system became 1.0 mmol / liter. Subsequently, ethylene was passed through the system at normal pressure while stirring to set the inside of the system to an ethylene atmosphere. The internal temperature of the autoclave was maintained at 70°C, and the internal pressure was adjusted to 6 kg / cm in terms of gauge pressure with ethylene 2 The pressure was applied so as to satisfy the requirement. After stirring for 10 minutes, 0.4 liter of a toluene solution containing isopropylidene(cyclopentadienyl)(indenyl)zirconium dichloride and methylalumoxane prepared in advance was added into the system to initiate the copolymerization reaction of ethylene and norbornene. The catalyst concentrations herein are 0.018 mmol / liter of isopropylidene(cyclopentadienyl)(indenyl)zirconium dichloride and 8.0 mmol / liter of methylalumoxane relative to the entire system. During this copolymerization reaction, by continuously supplying ethylene into the system, the temperature was maintained at 70°C and the internal pressure was maintained at 6 kg / cm in terms of gauge pressure 2 The pressure and temperature were maintained as described above. After 60 minutes, isopropyl alcohol was added to terminate the copolymerization reaction. After depressurization, the polymer solution was taken out, and then contacted with an aqueous solution obtained by adding 5 liters of concentrated hydrochloric acid to 1 m 3 of water at a ratio of 1:1 under vigorous stirring, so that catalyst residues were transferred to the aqueous phase. After allowing the contacted mixed solution to stand, the aqueous phase was separated and removed, followed by washing with water twice, to purify and separate the polymerization liquid phase. Next, the purified and separated polymerization liquid phase was contacted with three times the volume of acetone under vigorous stirring to precipitate the copolymer, then the solid part (copolymer) was collected by filtration and sufficiently washed with acetone. Further, in order to extract unreacted monomers, this solid part was adjusted to 40 kg / m 3 After putting the solid part into acetone to satisfy the above concentration, extraction was performed at 60°C for 2 hours. After the extraction treatment, the solid part was collected by filtration, and dried at 130°C under 350 mmHg for 12 hours under a nitrogen stream to obtain an ethylene-norbornene copolymer (copolymer B). In the same manner as in which pellet A of the ring-opening polymer hydrogenated material was prepared in Production Example 1, A-1-2, ethylene-norbornene copolymer (copolymer B) was pelletized. The weight-average molecular weight (Mw) of this pelletized ethylene-norbornene copolymer (copolymer B) was 96,000, the molecular weight distribution (Mw / Mn) was 2.4, and the Tg was 138°C.

[0091] [Comparative Examples 1 and 2] The procedure was carried out in the same manner as in Example 1, except that a mixed solvent of 99% cyclohexane and 1% methylcyclohexane (Comparative Example 1) or a mixed solvent of 78% cyclohexane and 22% methylcyclohexane (Comparative Example 2) was used as the mixed solvent.

[0092] [Comparative Example 3] The procedure was carried out in the same manner as in Example 1, except that cyclohexane alone was used as the solvent instead of the mixed solvent.

[0093] [Comparative Example 4] The procedure was carried out in the same manner as in Example 11, except that cyclohexane alone was used as the solvent instead of the mixed solvent.

[0094] [result] The results of the examples and comparative examples are shown in Table 1. [Table 1]

[0095] Abbreviations and other terms in Table 1 AO antioxidant ΔYi Yellowness

[0096] Table 1 shows that by using a mixed solvent within the scope of the present invention, excellent results were obtained for each evaluation item, demonstrating that the degree of foreign matter removal in recycled alicyclic structure-containing polymer resin molded articles is superior when using a mixed solvent within the scope of the present invention. Furthermore, a comparison between Example 11 and Comparative Example 4 shows that the degree of foreign matter removal in recycled articles is also superior when the present invention is applied to addition-type alicyclic structure-containing polymer resins. [Industrial applicability]

[0097] According to the present invention's method for reusing resin molded articles, it is possible to obtain recycled resin molded articles containing alicyclic structure-containing polymers with improved physical properties such as color tone, while further suppressing appearance defects.

Claims

1. A method for reusing a resin molded article containing an alicyclic structure polymer, comprising the steps of: pulverizing the resin molded article to obtain a molded article pulverized product; and dissolving the molded article pulverized product in a mixed solvent containing 80% to 98% by weight of cyclohexane and 2% to 20% by weight of a hydrocarbon or aromatic solvent with a freezing point of -40°C or lower, based on 100% by weight of the mixed solvent, to obtain a polymer solution. A method for reusing a resin molded article containing an alicyclic structure-containing polymer, characterized in that the alicyclic structure-containing polymer is selected from the group consisting of a ring-opening polymer of a norbornene monomer, a ring-opening copolymer of a norbornene monomer and other monomers capable of ring-opening copolymerization, and hydrogenated products thereof, an addition polymer of a norbornene monomer, and an addition copolymer of a norbornene monomer and other monomers capable of ring-opening copolymerization.

2. The method for recycling a resin molded article according to Claim 1, wherein the proportion of repeating units containing an alicyclic structure in the alicyclic structure-containing polymer is 50% by weight or more.

3. A method for reusing a resin molded body according to claim 1 or 2, further comprising a step of sieving the pulverized molded body with a sieve of φ3 mm or more and 15 mm or less between the step of pulverizing the resin molded body and the step of dissolving the pulverized molded body.

4. A method for reusing a resin molded article according to any one of claims 1 to 3, wherein the boiling point of the solvent is 150°C or lower.

5. The method for reusing a resin molded article according to any one of claims 1 to 4, wherein the hydrocarbon or aromatic solvent with a freezing point of -40°C or lower is methylcyclohexane or toluene.

6. A method for reusing a resin molded article according to any one of claims 1 to 5, further comprising the step of adding an adsorbent to a molded article pulverization dissolution system.

7. A method for reusing a resin molded article according to claim 6, wherein the adsorbent is acid clay, activated clay, activated alumina, or zeolite.

8. A method for reusing a resin molded article according to any one of claims 6 or 7, further comprising the step of filtering the polymer solution in solution state to remove foreign matter and adsorbents.

9. The method for reusing a resin molded article according to claim 8, wherein the ratio of the amount of pulverized molded article to the total amount of the mixed solvent and pulverized molded article in the polymer solution when the solution is filtered is 10% by weight or more and 20% by weight or less.

10. A method for reusing a resin molded article according to any one of claims 1 to 9, further comprising the steps of: removing a mixed solvent from a polymer solution to recover a resin containing an alicyclic structure polymer; melting the recovered resin; and filtering the molten resin in a molten state.

11. A method for reusing a resin molded article according to any one of claims 1 to 10, wherein the glass transition temperature of the alicyclic structure-containing polymer is 70°C or higher and 170°C or lower.

12. A method for reusing a resin molded article according to any one of claims 1 to 11, wherein the resin molded article used as a raw material has a urethane layer with a thickness of 100 nm or less.

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