Glutarimide Resin

Abstract

A glutarimide resin which comprises repeating units represented by formula (1) (wherein R1 and R2 each independently represent a hydrogen atom or a C1-C8 alkyl group), repeating units represented by formula (2) (wherein R3 and R4 each independently represent a hydrogen atom or a C1-C8 alkyl group), and repeating units represented by formula (3) (wherein R5 and R6 each independently represent a hydrogen atom or a C1-C8 alkyl group and R7 represents a C1-C18 alkyl group, a C3-C12 cycloalkyl group, or a substituent including a C5-C15 aromatic ring) and which satisfies the following relationship. Relationship: 3≤(M1+M2)≤20 (M1 is the content (mol%) of the repeating units represented by formula (1) and M2 is the content (mol%) of the repeating units represented by formula (2).)

Description

[Technical Field]

[0001] The present invention relates to a glutarimide resin, a method for producing the same, and a film and a substrate using the resin. [Background technology]

[0002] Liquid crystal display devices are equipped with various films, such as polarizing films, to maintain their display quality. Furthermore, plastic liquid crystal display devices, which use resin films instead of glass substrates, have been put to practical use in order to further reduce the weight of liquid crystal display devices for personal digital assistants and mobile phones.

[0003] As a resin constituting an optical film that can be used in such liquid crystal display devices, a (meth)acrylic resin containing a glutarimide unit is known (see, for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-261025 [Patent Document 2] Japanese Patent Application Laid-Open No. 2008-255175 Summary of the Invention [Problem to be solved by the invention]

[0005] Polarizer protective films for liquid crystal displays are required to have a small retardation, which is expressed as the product of birefringence and thickness. Furthermore, the retardation of the film is sometimes required to be resistant to changes due to external stress, etc.

[0006] Patent Document 1 describes a resin having a glutarimide structure for use in a polarizer protective film, and exemplified methylamine as a modifier. However, when modified with methylamine, there was room for improvement in the balance with heat resistance in order to reduce the orientation birefringence to a practically sufficient level.

[0007] Patent Document 2 discloses a glutarimide resin obtained by copolymerizing methyl methacrylate and methacrylamide and then cyclizing the copolymer. However, it is difficult for this glutarimide resin to have both heat resistance and a practically small orientation birefringence. In view of the above-mentioned current situation, an object of the present invention is to provide a glutarimide resin that has excellent heat resistance and small orientation birefringence. [Means for solving the problem]

[0008] Therefore, as a result of extensive research, the present inventors have found that by modifying a raw material resin such as polymethyl methacrylate with ammonia, a glutarimide resin having sufficient heat resistance can be obtained while maintaining orientation birefringence at a level small enough for practical use.

[0009] Furthermore, it was found that modification with ammonia not only allows two types of glutarimide ring structures to be simultaneously introduced into the resulting glutarimide resin, but also results in a resin that is excellent not only in the balance between orientation birefringence and heat resistance, but also in handleability during production.

[0010] That is, the present invention provides a repeating unit represented by the following general formula (1):

[0011] [ka]

[0012] (In the formula, R 1 and R 2 each independently represents hydrogen or an alkyl group having 1 to 8 carbon atoms. A repeating unit represented by the following general formula (2):

[0013] [ka]

[0014] (In the formula, R 3 and R4 each independently represents hydrogen or an alkyl group having 1 to 8 carbon atoms. and a repeating unit represented by the following general formula (3):

[0015] [ka]

[0016] (In the formula, R 5 and R 6 each independently represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms; R 7 represents an alkyl group having 1 to 18 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, or a substituent containing an aromatic ring having 5 to 15 carbon atoms. The glutarimide resin is characterized in that it satisfies the following formula (a): 3≦M1+M2≦20 (a) (In the formula, M1 is the content (mol %) of the repeating unit represented by formula (1) in the glutarimide resin, and M2 is the content (mol %) of the repeating unit represented by formula (2) in the glutarimide resin. M1>0 and M2>0.) Preferably, the glutarimide resin has a glass transition temperature of 120° C. or higher. Preferably, the glutarimide resin has a 5% weight loss temperature of 350° C. or higher in TGA measurement. Preferably, the glutarimide resin has an orientation birefringence of −0.01×10 -3 ~2.0×10 -3 is. The present invention also relates to a glutarimide resin composition containing the glutarimide resin. The present invention also relates to an optical film containing the glutarimide resin composition. Preferably, the optical film has an in-plane retardation Re of 10 nm or less at a wavelength of 590 nm, and an absolute value of a thickness direction retardation Rth of 40 nm or less. The present invention may be a polarizer protective film including the optical film. The present invention may also be directed to a substrate containing the glutarimide resin composition. The present invention also relates to a method for producing a glutarimide resin, which includes a step of reacting a raw material resin having an acrylic acid ester monomer unit content of less than 1% by weight and a repeating unit represented by the general formula (3) with ammonia. [Effects of the Invention]

[0017] The present invention provides a glutarimide resin having excellent heat resistance and small orientation birefringence, and also provides a simple production method that allows two types of glutarimide ring structures to be simultaneously introduced. Furthermore, the glutarimide resin according to the present invention has good heat resistance even when the amount of imidizing agent used in the production is reduced, and therefore the reaction time in the imidization step can be shortened, thereby improving productivity and reducing the amount of gas emitted in the imidization step. DETAILED DESCRIPTION OF THE INVENTION

[0018] (glutarimide resin) The glutarimide resin according to the present disclosure comprises a repeating unit represented by the following general formula (1):

[0019] [ka]

[0020] A repeating unit represented by the following general formula (2):

[0021] [ka]

[0022] and contains a repeating unit represented by the following general formula (3):

[0023] [ka]

[0024] In the formula (1), R 1 and R 2 R each independently represents hydrogen or an alkyl group having 1 to 8 carbon atoms. 1 A methyl group is preferred as R. 2 is preferably a hydrogen atom. In the formula (2), R 3 and R 4 R each independently represents hydrogen or an alkyl group having 1 to 8 carbon atoms. 3 A methyl group is preferred as R. 4 is preferably a hydrogen atom. In the formula (3), R 5 and R 6 each independently represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms; R 7 represents an alkyl group having 1 to 18 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, or a substituent containing an aromatic ring having 5 to 15 carbon atoms. 5 Hydrogen is preferred as R. 6 A methyl group is preferred as R. 7 is preferably a methyl group.

[0025] Specifically, the repeating unit represented by the formula (3) may be a (meth)acrylate ester unit. Examples include structures derived from methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, benzyl (meth)acrylate, cyclohexyl (meth)acrylate, etc. These may contain two or more different types. Methyl methacrylate units are preferred because they provide an excellent balance between heat resistance and orientation birefringence. The proportion of the methyl methacrylate units in the repeating units represented by formula (3) is preferably 50 to 100 mol %, more preferably 70 to 100 mol %, even more preferably 80 to 100 mol %, and particularly preferably 90 to 100 mol %.

[0026] The glutarimide resin according to the present disclosure satisfies the following formula (a): 3≦M1+M2≦20 (a) In the formula, M1 is the content (mol %) of the repeating unit represented by the formula (1) in the glutarimide resin, and M2 is the content (mol %) of the repeating unit represented by the formula (2) in the glutarimide resin. M1>0 and M2>0.

[0027] In the glutarimide resin according to the present disclosure, from the viewpoint of heat resistance, the larger the value of M1+M2, the better, specifically, the lower limit is 3 mol% or more, preferably 4 mol% or more, and more preferably 5 mol% or more. From the viewpoint of orientation birefringence, the smaller the value of M1+M2, the better, specifically, the upper limit is 20 mol% or less, preferably 17 mol% or less, more preferably 15 mol% or less, even more preferably 12 mol% or less, still more preferably 10 mol% or less, and particularly preferably 8 mol% or less.

[0028] A glutarimide resin having M1+M2 in this range can improve heat resistance while maintaining orientation birefringence at a level sufficiently small for practical use. If M1+M2 is less than 3 mol%, heat resistance may be insufficient, while if it is more than 20 mol%, orientation birefringence may become high, which may be undesirable depending on the application. The glutarimide resin according to the present disclosure has good heat resistance even when the value of M1+M2 is relatively small. If the value of M1+M2 is large, the glutarimide resin may become brittle when formed into a film, but if the value of M1+M2 is within the above range, the brittleness of the film can be avoided.

[0029] Both the repeating unit represented by formula (1) and the repeating unit represented by formula (2) contribute to heat resistance and orientation birefringence, but the repeating unit represented by formula (1) not only contributes more to heat resistance than the repeating unit represented by formula (2), but also contributes more to orientation birefringence. That is, by including the repeating unit represented by formula (1) and the repeating unit represented by formula (2), it is possible to efficiently achieve both heat resistance and substantially small orientation birefringence. Furthermore, the repeating unit represented by formula (2) can suppress the increase in viscosity of the glutarimide resin more than the repeating unit represented by formula (1), which makes handling in subsequent manufacturing steps easier.

[0030] Furthermore, the glutarimide resin according to the present disclosure preferably satisfies the following formula (b): 0.5≦M1 / M2≦2.0 (b) Within this range, high heat resistance and small orientation birefringence can be achieved at the same time at a higher level. More preferably, 0.7≦M1 / M2≦1.7, and even more preferably, 0.8≦M1 / M2≦1.5.

[0031] The values ​​of M1 and M2 are not particularly limited as long as they are within the ranges satisfying the formula (a) and preferably the formula (b). Preferably, M1 is 0.5 mol% or more, more preferably 1 mol% or more, and even more preferably 1.2 mol% or more. Also, M2 is preferably 0.5 mol% or more, more preferably 1 mol% or more, and even more preferably 1.2 mol% or more.

[0032] M1 and M2 are 1 In the chart obtained by H-NMR measurement, the area of ​​the peaks derived from each structure is calculated, and the ratio of these areas can be used to determine the ratio. An example is shown below. 1 Using H-NMR BRUKER AvanceNEO700 (700MHz), 30 mg of resin was dissolved in 0.75 ml of deuterated DMSO. 1H-NMR measurement is performed. The area A of the peak derived from the O-CH3 proton of methyl methacrylate in the vicinity of 3.5 to 3.8 ppm is divided by 3 to obtain a value A', the area B of the peak derived from the N-CH3 proton of formula (2) in the vicinity of 3.0 to 3.3 ppm is divided by 3 to obtain a value B', the area C of the peak derived from the NH proton of formula (1) in the vicinity of 10.4 to 10.9 ppm, and the area D of the peak derived from the COOH proton in the vicinity of 12.3 to 12.9 ppm are calculated, and the chromatogram can be obtained using the following formula.

[0033] M1=C / (A'+B'+C+D)×100 M2 = B' / (A'+B'+C+D) x 100

[0034] The content M3 of the repeating unit represented by the formula (3) in the glutarimide resin is not particularly limited as long as it is within a range satisfying the formula (a) and preferably the formula (b). Preferably, M3 is 70 to 97 mol %, more preferably 75 to 96 mol %, and even more preferably 80 to 95 mol %. M3 can be calculated in the same way as M1 and M2. In the example described above, M3 can be calculated using the following formula: M3 = A' / (A'+B'+C+D) x 100

[0035] The glass transition temperature of the glutarimide resin is preferably 120° C. or higher, more preferably 125° C. or higher, even more preferably 128° C. or higher, even more preferably 130° C. or higher, and particularly preferably 135° C. or higher. The glass transition temperature can be determined by the midpoint method using 10 mg of resin, measured in a nitrogen atmosphere at a heating rate of 20° C. / min using a differential scanning calorimeter (DSC, Shimadzu Corporation, Model DSC-50).

[0036] The 5% weight loss temperature in TGA measurement of the glutarimide resin is preferably 350° C. or higher, more preferably 353° C. or higher, even more preferably 355° C. or higher, even more preferably 360° C. or higher, particularly preferably 365° C. or higher, and most preferably 369° C. or higher. The 5% weight loss temperature in TGA measurement can be measured using a thermogravimetric analyzer (TGA: Hitachi High-Tech Science Corporation: STA7200) by heating 15 mg of resin in a nitrogen atmosphere from room temperature at a rate of 10° C. / min, and determining the temperature at which the thermal weight loss (wt%) of the resin reaches 5%.

[0037] The glutarimide resin according to the present disclosure has an orientation birefringence of −0.01×10 -3 That's it, 2.0 x 10 -3 Preferably, it is 1.5 x 10 or less. -3 Less than 1.0 x 10 is preferable. -3 Less than 0.5 × 10 is more preferable. -3 Even more preferable is 0.25×10 -3 The following are particularly preferred: If the orientation birefringence is outside the above range, applications may be limited. In this specification, unless otherwise specified, the term "orientation birefringence" refers to the birefringence measured on a stretched film obtained by forming a glutarimide resin into a film and stretching the film 100% at a temperature 5°C higher than the glass transition temperature of the resin. Orientation birefringence (Δn) is defined as Δn = nx - ny = Re / d and can be measured with a retardation meter.

[0038] The photoelastic coefficient of the glutarimide resin according to the present disclosure is 20×10 -12 m 2 / N or less, and 10 × 10 -12 m 2 / N or less is more preferable, and 5×10 -12 m 2 It is more preferable that the absolute value of the photoelastic coefficient is 20×10 / N or less. -12 m 2 If it is greater than / N, light leakage is likely to occur, and this tendency becomes more pronounced in high temperature and high humidity environments in particular.

[0039] The photoelastic coefficient is the ratio of the stress to the birefringence (Δn) of an isotropic solid, which is called the photoelastic coefficient c. c=Δn / ΔF It is shown as follows. In the present application, the photoelastic coefficient is a value measured by the Senarmont method at a wavelength of 515 nm at 23° C. and 50% RH.

[0040] The acid value of a resin represents the content of carboxylic acid units and acid anhydride units in the resin, and can be calculated, for example, by the titration method described in WO 2005 / 054311. The glutarimide resin according to the present disclosure preferably has an acid value of 0.10 to 1.00 mmol / g. When the acid value is within this range, the glutarimide resin has an excellent balance of heat resistance, mechanical properties, and moldability.

[0041] Among the acid components, the content of carboxylic acid is preferably 0.25 mmol / g or less, more preferably 0.20 mmol / g or less, from the viewpoint of molding processability. The amount of carboxylic acid can be measured by using the acid value (DMSO acid value) obtained by changing the solvent from methanol to dimethyl sulfoxide in the titration method described in WO 2005 / 054311. Specifically, (Amount of carboxylic acid) = 2 × (Acid value) - (DMSO acid value) In titration with methanol, one molecule of acid anhydride is counted as one molecule, whereas in titration with dimethyl sulfoxide, one molecule of acid anhydride is counted as two molecules, so the above formula can be applied.

[0042] From the viewpoint of thermal stability, the content of acrylate units contained in the glutarimide resin according to the present disclosure is preferably less than 1 wt%, more preferably less than 0.5 wt%, and particularly preferably less than 0.3 wt%. There is no particular lower limit, and the lower the content, the better, and it is more preferable that no acrylate units are contained.

[0043] Furthermore, when the glutarimide resin is produced by heating and cyclizing a raw material resin polymerized by adjusting the monomer species and monomer ratio, the content of acrylic ester units in the glutarimide resin may be substituted with the content of acrylic esters in all the monomers charged into the raw material resin. Needless to say, when an acrylic ester is not used as a monomer, the content of acrylic ester units in the glutarimide resin will be 0%.

[0044] The glutarimide resin may further contain copolymerized units other than the repeating units represented by the formulas (1) to (3), carboxylic acid units and carboxylic anhydride units, as required.

[0045] Examples of other units include aromatic vinyl monomer units such as styrene, nitrile monomer units such as acrylonitrile and methacrylonitrile, and maleimide monomer units such as maleimide, N-methylmaleimide, N-phenylmaleimide, and N-cyclohexylmaleimide. These other units may be directly copolymerized or graft copolymerized into the glutarimide resin.

[0046] The weight-average molecular weight of the glutarimide resin is not particularly limited, but is preferably 1×10 4 ~5×10 5 Preferably, it is 5 x 10 4 ~3×10 5 Within the above range, the molding processability and the mechanical strength during film processing can be improved.

[0047] (Method of manufacturing glutarimide resin) To produce the glutarimide resin according to the present disclosure, it is preferable to react a raw material resin having a repeating unit represented by the above-mentioned general formula (3) with ammonia. The raw material resin is preferably a polymer having an acrylic acid ester monomer unit content of less than 1 wt% and having a repeating unit represented by the following general formula (3). The raw material resin is preferably a polymethyl methacrylate resin, and particularly preferably a polymethyl methacrylate resin having an acrylic acid ester monomer unit content of less than 1 wt%.

[0048] The content of the repeating unit represented by formula (3) in the raw material resin may be set as appropriate, but is preferably 50 to 100% by weight, more preferably 70 to 100% by weight, even more preferably 80 to 100% by weight, and particularly preferably 90 to 100% by weight.

[0049] The method for producing a glutarimide resin according to the present disclosure is not particularly limited, and may be, for example, a melt-kneading method including a heat-melting step of melting a polymethyl methacrylate resin, which is a suitable raw material resin, and an imidization step of treating the polymethyl methacrylate resin with an imidizing agent. Hereinafter, a method for producing a glutarimide resin using the melt-kneading method will be described.

[0050] (a) Polymethyl methacrylate resin First, methyl methacrylate is polymerized to produce a polymethyl methacrylate resin. The polymethyl methacrylate resin refers to a raw material resin in which the content of methyl methacrylate is preferably 50 to 100% by weight, more preferably 70 to 100% by weight, even more preferably 80 to 100% by weight, and particularly preferably 90 to 100% by weight. When producing a polymethyl methacrylate resin, other than methyl methacrylate, for example, methyl acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, benzyl (meth)acrylate, cyclohexyl (meth)acrylate, etc. may be used in combination. When these are used in combination, the content of acrylate ester monomer units is preferably less than 1% by weight, more preferably less than 0.5% by weight, and even more preferably less than 0.3% by weight.

[0051] In addition to the above-mentioned monomers, it is also possible to copolymerize aromatic monomers such as styrene and methylstyrene, nitrile monomers such as acrylonitrile and methacrylonitrile, and maleimide monomers such as maleimide, N-methylmaleimide, N-phenylmaleimide, and N-cyclohexylmaleimide.

[0052] The structure of the polymethyl methacrylate resin is not particularly limited, and may be any of a linear polymer, a block polymer, a core-shell polymer, a branched polymer, a ladder polymer, a crosslinked polymer, etc. In the case of a block polymer, it may be any of AB type, ABC type, ABA type, and other types of block polymers. In the case of a core-shell polymer, it may be composed of only one core layer and one shell layer, or each may be composed of multiple layers.

[0053] The method for producing polymethyl methacrylate resin is not particularly limited, and known methods such as emulsion polymerization, emulsion-suspension polymerization, suspension polymerization, bulk polymerization, and solution polymerization can be used. However, when used in the optical field, bulk polymerization and solution polymerization are particularly preferred from the viewpoint of producing fewer impurities. For example, polymethyl methacrylate resin can be produced in accordance with the methods described in JP-A-56-8404, JP-B-6-86492, JP-B-7-37482, or JP-B-52-32665.

[0054] (b) Imidization step The method for producing a glutarimide resin according to the present disclosure includes a step of heating and melting the polymethyl methacrylate resin and treating it with an imidizing agent (imidization step), thereby producing a glutarimide resin. Ammonia is used as the imidizing agent. By performing imidization using ammonia, it is possible to introduce two types of glutarimide ring structures (the unit represented by the formula (1) and the unit represented by the formula (2)).

[0055] In conventional imidization using methylamine, it is necessary to increase the imidization rate to improve heat resistance, which tends to reduce productivity by requiring a long time for the imidization process.Furthermore, if the imidization rate is too high, the glutarimide resin may become brittle when formed into a film. In contrast, imidization using ammonia can improve the heat resistance of the resulting glutarimide resin even if the imidization ratio (M1 + M2) is low, compared to conventional imidization using methylamine. Because a low imidization ratio is sufficient, the reaction time in the imidization step can be shortened and brittleness when formed into a film can be avoided.

[0056] As the ammonia, liquefied ammonia or aqueous ammonia may be used. From the viewpoint of productivity, it is preferable to use liquid ammonia because it has good compatibility with the polymethyl methacrylate resin and high reaction efficiency. Liquid ammonia has a higher concentration than aqueous ammonia diluted with water, and can be reacted with a smaller amount added. The concentration of aqueous ammonia is not particularly limited, but is preferably about 25 to 35% by weight in consideration of availability and reactivity.

[0057] In this imidization step, by adjusting the addition ratio of the imidizing agent, it is possible to adjust the ratio of the repeating unit represented by formula (1), the repeating unit represented by formula (2), and the repeating unit represented by formula (3) in the obtained glutarimide resin. Furthermore, by adjusting the degree of imidization, it is possible to adjust the physical properties of the obtained glutarimide resin and the optical properties of an optical film obtained by molding the glutarimide resin composition.

[0058] The amount of imidizing agent used can be adjusted appropriately depending on the required properties. For example, as long as it is 0.5 parts by weight or more per 100 parts by weight of the raw material resin, it can be adjusted appropriately depending on the required properties. It is preferably 0.6 parts by weight or more, more preferably 0.7 parts by weight or more, and even more preferably 0.8 parts by weight or more. If it is less than 0.5 parts by weight, the heat resistance of the resulting glutarimide resin composition may be reduced. The upper limit can be selected appropriately in relation to moldability and physical properties. From the perspective of ease of handling, it is preferably 30 parts by weight or less, more preferably 20 parts by weight or less, even more preferably 10 parts by weight or less, even more preferably 5 parts by weight or less, particularly preferably 3 parts by weight or less, and most preferably 2 parts by weight or less. When the imidizing agent is aqueous ammonia, the amount of the imidizing agent used refers to the amount used in terms of ammonia contained in the aqueous ammonia. In this imidization step, in addition to the imidization agent, a ring closure promoter (catalyst) may be added as needed.

[0059] The method of heating and melting the resin and treating it with an imidizing agent is not particularly limited, and any conventionally known method can be used. For example, the polymethyl methacrylate resin can be imidized by a method using an extruder, a batch-type reaction tank (pressure vessel), or the like.

[0060] When the resin is heated and melted using an extruder and treated with an imidizing agent, the extruder to be used is not particularly limited, and various extruders can be used, specifically, for example, a single-screw extruder, a twin-screw extruder, a multi-screw extruder, etc.

[0061] Among these, it is preferable to use a twin-screw extruder, which can promote mixing of the imidizing agent (and the ring-closure accelerator, if used) with the polymethyl methacrylate resin.

[0062] Examples of twin-screw extruders include non-intermeshing co-rotating types, intermeshing co-rotating types, non-intermeshing counter-rotating types, and intermeshing counter-rotating types. Among these, it is preferable to use an intermeshing co-rotating type. An intermeshing co-rotating twin-screw extruder is capable of high-speed rotation, and therefore can further promote mixing of the imidization agent (if a ring-closure accelerator is used, the imidization agent and the ring-closure accelerator) with the raw material resin. The extruders exemplified above may be used alone or in combination with a plurality of extruders connected in series. For example, the tandem reactive extruder described in JP-A-2008-273140 may be used.

[0063] When imidization is carried out in an extruder, for example, polymethyl methacrylate resin is charged into the raw material charging port of the extruder, the resin is melted, and the cylinder is filled with the resin. Then, an imidizing agent is injected into the extruder using an addition pump, whereby the imidization reaction can proceed in the extruder.

[0064] In this case, the reaction zone temperature (resin temperature) in the extruder is preferably 180°C to 300°C, and more preferably 200 to 290°C. If the reaction zone temperature (resin temperature) is less than 180°C, the imidization reaction hardly progresses, and heat resistance tends to decrease. If the reaction zone temperature exceeds 300°C, decomposition of the resin becomes significant, and the flex resistance of the film that can be formed from the resulting glutarimide resin tends to decrease. Here, the reaction zone in the extruder refers to the region in the extruder cylinder between the injection position of the imidization agent and the resin discharge port (die portion).

[0065] Imidization can be promoted by extending the reaction time in the reaction zone of the extruder. The reaction time in the reaction zone of the extruder is preferably longer than 10 seconds, and more preferably longer than 30 seconds. If the reaction time is shorter than 10 seconds, imidization may not proceed very much.

[0066] The resin pressure in the extruder is preferably in the range of atmospheric pressure to 50 MPa, more preferably in the range of 1 MPa to 30 MPa. If the pressure is less than 1 MPa, the solubility of the imidizing agent is low, and the progress of the reaction tends to be inhibited. If the pressure is more than 50 MPa, the mechanical pressure limit of a normal extruder is exceeded, requiring special equipment, which is not preferable from the viewpoint of cost.

[0067] When an extruder is used, it is preferable to equip it with a vent hole that can reduce the pressure to below atmospheric pressure in order to remove unreacted imidizing agent and by-products. With such a configuration, it is possible to remove unreacted imidizing agent, by-products such as methanol, and monomers. In addition, in place of an extruder, a reaction apparatus capable of handling high viscosity materials, such as a horizontal twin-screw reaction apparatus such as Vivolac manufactured by Sumitomo Heavy Industries, Ltd., or a vertical twin-screw stirring tank such as Superblend, can also be suitably used in the production of the glutarimide resin.

[0068] When the glutarimide resin is produced using a batch reaction vessel (pressure vessel), the structure of the batch reaction vessel (pressure vessel) is not particularly limited. Specifically, it is sufficient if the polymethyl methacrylate resin has a structure that allows it to be melted by heating and stirred, and to which an imidizing agent (when a ring-closure accelerator is used, the imidizing agent and the ring-closure accelerator) can be added, but it is preferable that the structure has good stirring efficiency.

[0069] Such a batch-type reaction tank (pressure vessel) can prevent the polymer viscosity from increasing as the reaction proceeds, resulting in insufficient stirring. An example of a batch-type reaction tank (pressure vessel) having such a structure is the Max Blend stirring tank manufactured by Sumitomo Heavy Industries, Ltd. Specific examples of the imidization method include known methods such as those described in JP-A Nos. 2008-273140 and 2008-274187. The glutarimide resins according to the present disclosure may be further reacted with ammonia.

[0070] (c) Esterification step The method for producing a glutarimide resin according to the present disclosure can include, in addition to the imidization step, a step of treating with an esterifying agent, which allows the acid value of the glutarimide resin obtained in the imidization step to be adjusted within a desired range. Examples of the esterifying agent include dimethyl carbonate, 2,2-dimethoxypropane, dimethyl sulfoxide, triethyl orthoformate, trimethyl orthoacetate, trimethyl orthoformate, diphenyl carbonate, dimethyl sulfate, methyl toluene sulfonate, methyl trifluoromethyl sulfonate, methyl acetate, methanol, ethanol, methyl isocyanate, p-chlorophenyl isocyanate, dimethylcarbodiimide, dimethyl-t-butylsilyl chloride, isopropenyl acetate, dimethyl urea, tetramethylammonium hydroxide, dimethyldiethoxysilane, tetra-N-butoxysilane, dimethyl(trimethylsilane) phosphite, trimethyl phosphite, trimethyl phosphate, tricresyl phosphate, diazomethane, ethylene oxide, propylene oxide, cyclohexene oxide, 2-ethylhexyl glycidyl ether, phenyl glycidyl ether, and benzyl glycidyl ether. Among these, dimethyl carbonate and trimethyl orthoacetate are preferred from the viewpoints of cost, reactivity, etc., and dimethyl carbonate is preferred from the viewpoint of cost. In this esterification step, the amount of the esterification agent used is preferably 0 to 12 parts by weight, more preferably 0 to 8 parts by weight, relative to 100 parts by weight of the raw material resin.

[0071] If the amount of the esterifying agent is within the above range, the acid value can be adjusted to an appropriate range. On the other hand, if the amount is outside the above range, unreacted esterifying agent may remain in the resin, which may cause foaming or odor generation when the resin is molded.

[0072] In addition to the esterifying agent, a catalyst can also be used. The type of catalyst is not particularly limited, but examples include aliphatic tertiary amines such as trimethylamine, triethylamine, and tributylamine. Among these, triethylamine is preferred from the viewpoints of cost, reactivity, etc.

[0073] In this esterification step, only the heat treatment can be performed without using an esterifying agent. When only the heat treatment (kneading / dispersing the molten resin in the extruder) is performed, some or all of the carboxylic acids can be converted to acid anhydride groups through dehydration reactions between carboxylic acids in the glutarimide resin and / or dealcoholization reactions between carboxylic acids and alkyl ester groups, which are by-produced in the imidization step. In this case, a ring-closure accelerator (catalyst) can also be used. Even when treating with an esterifying agent, it is possible to promote the conversion to acid anhydride groups by heat treatment.

[0074] (d) Devolatilization process, filtration process The glutarimide resin that has been subjected to the imidization step and the optional esterification step contains unreacted imidizing agent, unreacted esterifying agent, volatile components by-produced by the reaction, resin decomposition products, etc., so it is possible to install a vent hole in the latter half of the extruder that can reduce the pressure to below atmospheric pressure.

[0075] Furthermore, a filter can be installed at the end of the extruder to reduce foreign matter in the glutarimide resin. A gear pump is preferably installed before the filter to increase the pressure of the glutarimide resin. The type of filter to be used is preferably a stainless steel leaf disc filter capable of removing foreign matter from the molten polymer, and the filter element is preferably a fiber type, a powder type, or a combination thereof.

[0076] (Glutarimide resin composition) The glutarimide resin according to the present disclosure can be blended with other resins and additives as needed to form a glutarimide resin composition. Additives include commonly used weathering stabilizers such as antioxidants, heat stabilizers, light stabilizers, UV absorbers, and radical scavengers, as well as catalysts, plasticizers, lubricants, antistatic agents, colorants, shrinkage inhibitors, antibacterial agents, and deodorizing agents, either singly or in combination, to the extent that the object of the invention is not impaired. These additives can also be added when molding or processing the glutarimide resin or glutarimide resin composition described below.

[0077] The glutarimide resin composition according to the present disclosure preferably contains an ultraviolet absorber. The glutarimide resin according to the present disclosure has good compatibility with ultraviolet absorbers, allowing for a wider range of applications. Examples of ultraviolet absorbers include triazine-based compounds, benzotriazole-based compounds, benzophenone-based compounds, cyanoacrylate-based compounds, benzoxazine-based compounds, and oxadiazole-based compounds. Among these, triazine-based compounds are preferred in terms of ultraviolet absorption performance relative to the amount added. Any commercially available triazine-based compound can be used.

[0078] The ultraviolet absorber preferably has a maximum absorption wavelength of 300 nm or more and 370 nm or less. When exposed to ultraviolet light, a glutarimide resin composition containing such an ultraviolet absorber efficiently suppresses degradation caused by ultraviolet-A rays (wavelengths of 320 nm or more and 400 nm or less). Therefore, a relatively small amount of ultraviolet absorber can be added, and bleed-out due to an increased amount of ultraviolet absorber is unlikely to occur.

[0079] Furthermore, the ultraviolet absorber preferably has a 1% weight loss temperature of 350°C or higher under a nitrogen atmosphere. Triazine-based compounds are preferred because of their high heat resistance and large molar absorption coefficient. When a triazine-based compound is used, the amount added can be reduced, and contamination of molds (rolls, etc.) during processing can also be suppressed. Furthermore, as described in JP 2014-95926 A, ultraviolet absorbers using triazine-based compounds can improve thermal stability without the addition of a general thermal stabilizer.

[0080] Examples of such ultraviolet absorbers using triazine compounds include Tinuvin 1577, Tinuvin 460, Tinuvin 477, Tinuvin 479 (all manufactured by BASF), and LA-F70 (manufactured by ADEKA).

[0081] When the glutarimide resin composition according to the present disclosure contains an ultraviolet absorber, the amount of the ultraviolet absorber added is preferably 0.1 parts by weight or more and 5.0 parts by weight or less, and more preferably 0.4 parts by weight or more and 2.0 parts by weight or less, per 100 parts by weight of the glutarimide resin.

[0082] If the amount of ultraviolet absorber is less than 0.1 parts by weight, sufficient effect may not be obtained in applications requiring ultraviolet absorption, and if it is more than 2.0 parts by weight, bleeding out may occur during film formation.

[0083] In 27 g of the obtained glutarimide resin composition, the number of foreign particles of 20 μm or more is preferably 30 or less, more preferably 20 or less, and particularly preferably 10 or less. The number of foreign particles of 10 μm or more and less than 20 μm is preferably 300 or less, more preferably 200 or less, and particularly preferably 100 or less. The number of foreign particles of 5 μm or more and less than 10 μm is preferably 1,000 or less, more preferably 800 or less, and particularly preferably 500 or less.

[0084] The amount of foreign matter in the glutarimide resin composition was measured by weighing 10.0 to 10.5 g of the glutarimide resin composition and dissolving it in a mixed solution of 230 to 245 g of methylene chloride and 15 g of Cleansolve, and the number of foreign matters in five samples was counted. The total number of foreign matters in these samples is the amount of foreign matter in the glutarimide resin composition referred to in this application. The measuring device can be an automatic particle counter for liquids, System 8011-100 manufactured by HIAC Royco (measuring device main body: Model 8000A Counter, sampling device: Model ABS-2 Sampler, sensor: Model HRLD-100 Sensor).

[0085] (Other components contained in glutarimide resin composition) The glutarimide resin composition may contain a crosslinked elastomer to improve the mechanical strength of the glutarimide resin. The crosslinked elastomer can be produced by a known polymerization method such as suspension polymerization, dispersion polymerization, emulsion polymerization, solution polymerization, or bulk polymerization. In particular, to produce a crosslinked elastomer having a core-shell structure as described below, it is preferable to use a polymerization method such as suspension polymerization, dispersion polymerization, or emulsion polymerization.

[0086] The crosslinked elastomer is preferably a core-shell elastomer having a core layer made of a rubbery polymer and a shell layer made of a glassy polymer (hard polymer). Furthermore, the core layer made of a rubbery polymer may have one or more layers made of a glassy polymer as the innermost layer or intermediate layer.

[0087] The glass transition temperature Tg of the rubbery polymer constituting the core layer is preferably 20°C or lower, more preferably -60 to 20°C, and even more preferably -60 to 10°C. If the Tg of the rubbery polymer constituting the core layer exceeds 20°C, the improvement in mechanical strength of the glutarimide resin may be insufficient. The Tg of the glassy polymer (hard polymer) constituting the shell layer is preferably 50°C or higher, more preferably 50 to 140°C, and even more preferably 60 to 130°C. If the Tg of the glassy polymer constituting the shell layer is lower than 50°C, the heat resistance of the glutarimide resin may be reduced.

[0088] In this application, the glass transition temperatures of "rubber-like polymers" and "glassy polymers" are calculated using the Fox formula using values ​​given in the Polymer Handbook (J. Brandrup, Interscience 1989) (for example, the glass transition temperature of polymethyl methacrylate is 105°C, and that of polybutyl acrylate is -54°C).

[0089] The content of the core layer in the core-shell type elastic body is preferably 30 to 95% by weight, more preferably 50 to 90% by weight. The content of the glassy polymer layer in the core layer is 0 to 60%, preferably 0 to 45%, more preferably 10 to 40%, relative to 100% by weight of the total amount of the core layer. The content of the shell layer in the core-shell type elastic body is preferably 5 to 70% by weight, more preferably 10 to 50% by weight.

[0090] The core-shell type elastic body may contain any other appropriate components as long as the effects of the invention are not impaired.

[0091] As the polymerizable monomer for forming the rubber polymer constituting the core layer, any appropriate polymerizable monomer may be used.

[0092] The polymerizable monomers forming the rubbery polymer preferably contain alkyl(meth)acrylate, and the alkyl(meth)acrylate is preferably contained in an amount of 50% by weight or more, more preferably 50 to 99.9% by weight, and even more preferably 60 to 99.9% by weight, based on 100% by weight of the polymerizable monomers forming the rubbery polymer.

[0093] Examples of the alkyl (meth)acrylate include alkyl (meth)acrylates having an alkyl group of 2 to 20 carbon atoms, such as ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isononyl (meth)acrylate, lauroyl (meth)acrylate, and stearyl (meth)acrylate. These alkyl groups may have an alicyclic or aromatic cyclic substituent, a branched structure, or a functional group. Among these, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isononyl (meth)acrylate, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, and cyclohexyl (meth)acrylate are preferred, with butyl acrylate, 2-ethylhexyl acrylate, and isononyl acrylate being more preferred. These may be used alone or in combination of two or more.

[0094] The polymerizable monomers forming the rubber-like polymer preferably contain a polyfunctional monomer having two or more polymerizable functional groups in the molecule. The content of the polyfunctional monomer having two or more polymerizable functional groups in the polymerizable monomers forming the rubber-like polymer is preferably 0.01 to 20% by weight, more preferably 0.1 to 20% by weight, even more preferably 0.1 to 10% by weight, and particularly preferably 0.2 to 5% by weight.

[0095] Examples of the polyfunctional monomer having two or more polymerizable functional groups in the molecule include aromatic divinyl monomers such as divinylbenzene, alkane polyol poly(meth)acrylates such as ethylene glycol di(meth)acrylate, butylene glycol di(meth)acrylate, hexanediol di(meth)acrylate, oligoethylene glycol di(meth)acrylate, trimethylolpropane di(meth)acrylate, and trimethylolpropane tri(meth)acrylate, as well as urethane di(meth)acrylate, epoxy di(meth)acrylate, and triallyl isocyanurate. Examples of polyfunctional monomers having polymerizable functional groups of different reactivity include allyl (meth)acrylate, diallyl maleate, diallyl fumarate, and diallyl itaconate. Among these, ethylene glycol dimethacrylate, butylene glycol diacrylate, and allyl methacrylate are preferred. These may be used alone or in combination of two or more.

[0096] The polymerizable monomers forming the rubber-like polymer may include other polymerizable monomers copolymerizable with the alkyl (meth)acrylate and the polyfunctional monomer having two or more polymerizable functional groups in the molecule. The content of the other polymerizable monomers in the polymerizable monomers forming the rubber-like polymer is preferably 0 to 49.9 wt %, more preferably 0 to 39.9 wt %.

[0097] Examples of the other polymerizable monomers include aromatic vinyls such as styrene, vinyl toluene, and α-methyl styrene, aromatic vinylidenes, vinyl cyanides such as acrylonitrile and methacrylonitrile, vinylidene cyanide, methyl methacrylate, urethane acrylate, and urethane methacrylate.

[0098] The other polymerizable monomers may also be monomers having functional groups such as epoxy groups, carboxyl groups, hydroxyl groups, and amino groups. Specifically, examples of monomers having epoxy groups include glycidyl methacrylate, etc.; examples of monomers having carboxyl groups include methacrylic acid, acrylic acid, maleic acid, and itaconic acid; examples of monomers having hydroxyl groups include 2-hydroxyethyl methacrylate and 2-hydroxyethyl acrylate; and examples of monomers having amino groups include diethylaminoethyl methacrylate and diethylaminoethyl acrylate. These may be used alone or in combination of two or more.

[0099] The polymerizable monomers that form the rubbery polymer may be used in combination with a small amount of a chain transfer agent. Examples of such chain transfer agents include alkyl mercaptans such as octyl mercaptan, dodecyl mercaptan, and t-dodecyl mercaptan, and thioglycolic acid derivatives.

[0100] Any appropriate polymerizable monomer may be used as the polymerizable monomer for forming the glassy polymer constituting the shell layer and the glassy polymer layer in the core layer.

[0101] The polymerizable monomers forming the glassy polymer preferably contain at least one monomer selected from alkyl (meth)acrylates and aromatic vinyl monomers. The polymerizable monomers forming the glassy polymer preferably contain 50 to 100% by weight, more preferably 60 to 100% by weight, of at least one selected from alkyl (meth)acrylates and aromatic vinyl monomers, based on 100% by weight of the polymerizable monomers forming the glassy polymer.

[0102] The alkyl (meth)acrylate is preferably one in which the alkyl group has 1 to 8 carbon atoms. Furthermore, these alkyl groups may have an alicyclic or aromatic cyclic substituent, a branched structure, or a functional group. Examples of such alkyl (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, benzyl (meth)acrylate, cyclohexyl (meth)acrylate, butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate. Among these, methyl methacrylate is particularly preferred. These may be used alone or in combination of two or more.

[0103] Examples of the aromatic vinyl monomer include styrene, vinyl toluene, α-methyl styrene, etc. Among these, styrene is preferred. These may be used alone or in combination of two or more.

[0104] The polymerizable monomers that form the glassy polymer may contain a polyfunctional monomer having two or more polymerizable functional groups in the molecule. The polyfunctional monomer having two or more polymerizable functional groups in the molecule is preferably contained in an amount of 0 to 10% by weight, more preferably 0 to 8% by weight, and even more preferably 0 to 5% by weight, based on 100% by weight of the polymerizable monomers that form the glassy polymer.

[0105] Specific examples of the polyfunctional monomer having two or more polymerizable functional groups in the molecule include the same as those mentioned above.

[0106] The polymerizable monomers forming the glassy polymer may contain other polymerizable monomers copolymerizable with the alkyl (meth)acrylate and the polyfunctional monomer having two or more polymerizable functional groups in the molecule. The other polymerizable monomers are preferably contained in an amount of 0 to 50% by weight, more preferably 0 to 40% by weight, based on 100% by weight of the polymerizable monomers forming the glassy polymer.

[0107] Examples of the other polymerizable monomers include vinyl cyanides such as acrylonitrile and methacrylonitrile, vinylidene cyanide, alkyl (meth)acrylates other than those mentioned above, urethane acrylate, and urethane methacrylate. Furthermore, the monomer may have a functional group such as an epoxy group, a carboxyl group, a hydroxyl group, or an amino group. Examples of monomers having an epoxy group include glycidyl methacrylate. Examples of monomers having a carboxyl group include methacrylic acid, acrylic acid, maleic acid, and itaconic acid. Examples of monomers having a hydroxyl group include 2-hydroxymethacrylate and 2-hydroxyacrylate. Examples of monomers having an amino group include diethylaminoethyl methacrylate and diethylaminoethyl acrylate. These monomers may be used alone or in combination of two or more.

[0108] Furthermore, it is also preferable to use a small amount of a known chain transfer agent, similar to that used in the rubbery polymer layer, in combination with the polymerizable monomer that forms the glassy polymer.

[0109] As a method for producing the core-shell type elastomer, any appropriate method capable of producing core-shell type particles can be adopted.

[0110] For example, a method can be exemplified in which a polymerizable monomer that forms a rubbery polymer constituting the core layer is suspended or emulsion polymerized to produce a suspension or emulsion dispersion containing rubbery polymer particles, and then a polymerizable monomer that forms a glassy polymer that forms the shell layer is added to the suspension or emulsion dispersion and radically polymerized to obtain a core-shell type elastomer having a multilayer structure in which the surfaces of the rubbery polymer particles are coated with a glassy polymer. Here, the polymerizable monomer that forms the rubbery polymer and the polymerizable monomer that forms the glassy polymer may be polymerized in one stage, or in two or more stages with different composition ratios.

[0111] Preferred structures of the core-shell elastomer include, for example, (a) a structure having a soft, rubbery core layer and a hard, glassy shell layer, the core layer having a (meth)acrylic crosslinked elastic polymer layer, and (b) a structure having a multilayer structure in which the rubbery core layer has one or more glassy layers therein and further has a glassy shell layer outside the core layer. By appropriately selecting the monomer species of each layer, the physical properties of the glutarimide resin can be controlled as desired.

[0112] Specific examples of more preferred structures of the core-shell type elastomer include, for example, (A) a core-shell type elastomer in which the shell layer is a non-crosslinked methacrylic resin containing 3% by weight or more, more preferably 10% by weight or more, and even more preferably 15% by weight or more of alkyl acrylate; (B) a core-shell type elastomer in which the shell layer is made of two or more multi-layers with different alkyl acrylate contents and is a non-crosslinked methacrylic resin containing 10% by weight or more, more preferably 15% by weight or more of alkyl acrylate in total; (C) a core-shell type elastomer in which the core layer is made of an alkyl methacrylate Examples of suitable core-shell elastomers include (A) a multilayer structure in which a rubbery polymer layer is formed by polymerizing a mixture of alkyl acrylate, polyfunctional monomer, alkyl mercaptan, and other monomers in the presence of a glassy polymer layer obtained by polymerizing a mixture of alkyl acrylate, polyfunctional monomer, alkyl mercaptan, and other monomers as appropriate; and (B) a multilayer structure in which a core layer of the core-shell elastomer is formed by polymerizing a rubbery polymer layer using a peracid (such as persulfuric acid or perphosphate) as a thermal decomposition initiator in the presence of a glassy polymer layer obtained by polymerizing a mixture of alkyl acrylate, polyfunctional monomer, alkyl mercaptan, and other monomers as appropriate. These preferred core-shell elastomers may have a single structural design element, or two or more structural design elements may be used in combination. Such a structure facilitates good dispersion of the core-shell elastomer in the glutarimide resin according to the present disclosure, resulting in fewer defects due to undispersion or aggregation when formed into a film. Furthermore, the resulting film has excellent strength, toughness, heat resistance, transparency, and appearance, and is also less susceptible to whitening due to temperature changes or stress, resulting in a high-quality film.

[0113] When the core-shell elastomer is produced by emulsion polymerization, suspension polymerization, or the like, known polymerization initiators can be used. Particularly preferred polymerization initiators include persulfates such as potassium persulfate, ammonium persulfate, and ammonium persulfate; perphosphates such as sodium perphosphate; organic azo compounds such as 2,2-azobisisobutyronitrile; hydroperoxide compounds such as cumene hydroperoxide, tertiary butyl hydroperoxide, and 1,1-dimethyl-2-hydroxyethyl hydroperoxide; peresters such as tertiary butyl isopropyloxycarbonate and tertiary butyl peroxybutyrate; and organic peroxide compounds such as benzoyl peroxide, dibutyl peroxide, and lauryl peroxide. These initiators may be used as thermal decomposition polymerization initiators, or may be used as redox polymerization initiators in the presence of a catalyst such as ferrous sulfate and a water-soluble reducing agent such as ascorbic acid or sodium formaldehyde sulfoxylate. The initiator may be appropriately selected depending on the monomer composition to be polymerized, the layer structure, the polymerization temperature conditions, and the like.

[0114] When the core-shell elastomer is produced by emulsion polymerization, it can be produced by conventional emulsion polymerization using a known emulsifier. Examples of known emulsifiers include anionic surfactants such as phosphate ester salts, such as sodium alkyl sulfonate, sodium alkylbenzene sulfonate, sodium dioctyl sulfosuccinate, sodium lauryl sulfate, sodium fatty acid, and sodium polyoxyethylene lauryl ether phosphate, as well as nonionic surfactants, such as reaction products of alkylphenols or aliphatic alcohols with propylene oxide or ethylene oxide. These surfactants may be used alone or in combination. If necessary, cationic surfactants, such as alkylamine salts, may also be used. Among these, from the viewpoint of improving the thermal stability of the resulting core-shell elastomer, polymerization using a phosphate ester salt (alkali metal or alkaline earth metal), such as sodium polyoxyethylene lauryl ether phosphate, is particularly preferred. The core-shell elastomer latex obtained by emulsion polymerization is spray-dried, or as is commonly known, by adding an electrolyte or organic solvent as a coagulant to the latex to coagulate the polymer component, and then drying the polymer component by appropriate procedures such as heating, washing, and separation of the aqueous phase, to obtain a core-shell elastomer in the form of a mass or powder. Known coagulants such as water-soluble electrolytes and organic solvents can be used as coagulants, but from the standpoint of improving the thermal stability of the resulting copolymer during molding and in terms of productivity, it is preferable to use magnesium salts such as magnesium chloride or magnesium sulfate, or calcium salts such as calcium acetate or calcium chloride.

[0115] When the glutarimide resin composition according to the present disclosure contains a core-shell elastomer, the content of the core-shell elastomer is preferably 1 to 40 parts by weight, more preferably 2 to 35 parts by weight, and even more preferably 3 to 25 parts by weight, per 100 parts by weight of the glutarimide resin. If the content of the core-shell elastomer is less than 1 part by weight, the improvement in the mechanical strength of the glutarimide resin may be insufficient, and if it exceeds 40 parts by weight, the heat resistance of the glutarimide resin may be reduced.

[0116] The particle size of the soft core layer of the core-shell type elastic body is preferably 1 to 500 nm, more preferably 10 to 400 nm, even more preferably 50 to 300 nm, and particularly preferably 70 to 300 nm. If the particle size of the core layer of the core-shell type elastic body is less than 1 nm, the improvement in the mechanical strength of the glutarimide resin is insufficient, and if it is greater than 500 nm, the heat resistance and transparency of the glutarimide resin may be impaired.

[0117] The particle diameter of the core layer of the core-shell elastomer can be determined by molding a compound that is a 50:50 blend of core-shell crosslinked elastomer and Sumipex EX by weight, photographing the resulting film with a transmission electron microscope (JEOL JEM-1200EX) at an accelerating voltage of 80 kV using RuO4 staining ultrathin sectioning, randomly selecting 100 rubber particle images from the resulting photograph, and calculating the average particle diameter.

[0118] (Film containing glutarimide resin composition) The glutarimide resin composition can be formed into a film containing the glutarimide resin composition by a known forming method. The film containing the glutarimide resin composition preferably has a haze value of 2.0% or less, more preferably 1.0% or less, and a transmittance of 85% or more, more preferably 90% or more. It is preferable that both the haze value and the transmittance are within the above ranges, since this widens the range of applications in which the film can be used. Although there is no particular limitation on the optical anisotropy, it may be preferable that not only the optical anisotropy in the in-plane direction (length direction, width direction) but also the optical anisotropy in the thickness direction be small. In other words, it may be preferable that both the in-plane retardation and the thickness direction retardation be small.

[0119] More specifically, the in-plane retardation at a wavelength of 590 nm is preferably 10 nm or less, more preferably 5 nm or less, and even more preferably 1 nm or less.

[0120] Furthermore, the thickness direction retardation at a wavelength of 590 nm is preferably 40 nm or less, more preferably 15 nm or less, and even more preferably 3 nm or less.

[0121] The in-plane retardation (Re) and the thickness direction retardation (Rth) can be calculated by the following formulas.

[0122] Re=(nx-ny)×d Rth=|(nx+ny) / 2-nz|×d In the formula, nx, ny, and nz represent the refractive index in each axial direction, where the direction in which the in-plane refractive index is maximum is the X axis, the direction perpendicular to the X axis is the Y axis, and the thickness direction of the film is the Z axis. d represents the thickness of the film, and || represents the absolute value.

[0123] The film obtained from the glutarimide resin composition according to the present disclosure has a low amount of foreign matter. 2 It is preferable that the number of particles is 40 or less per m 2 More preferably, it is 30 pieces / m 2 It is particularly preferable that the foreign matter is within 1 m from the obtained stretched film. 2 The number of foreign particles larger than 20 μm was counted using a microscope, and the total number of foreign particles was calculated.

[0124] Films containing the glutarimide resin composition according to the present disclosure can be used as substrates for electronic materials, including antenna substrates, flexible display substrates, foldable display substrates, rollable display substrates, touch panel substrates, transparent display substrates, spatial display substrates, hologram substrates, signage substrates, head-up display peripheral components (viewpoint adjustment films, image adjustment films, image projection screens, retroreflective films, lens sheets, dust covers), brightness enhancement films, cover glass substitutes, glass substrate substitutes, reflective films, anti-reflective films, anti-glare films, substrates for double-sided and single-sided tapes and adhesive films for electronic devices, optical waveguides for AR glass, substrates for light-adjusting devices, substrates for light-blocking devices, high-frequency circuit board films, transparent flexible printed circuit boards, battery separator films, smartphone back covers, release films, and detector substrates for X-ray inspection equipment. In addition, the present invention can be suitably used in the imaging field such as taking lenses and viewfinders for cameras, VTRs and projectors, filters, prisms, Fresnel lenses, etc.; the lens field such as pickup lenses for optical discs such as CD players, DVD players and MD players; the optical recording field for optical discs such as CD players, DVD players and MD players; the information equipment field such as light guide plates for liquid crystal displays, films for liquid crystal displays such as polarizer protective films and retardation films, and surface protection films; the optical communications field such as optical fibers, optical switches and optical connectors; the vehicle field such as automobile headlight and tail lamp lenses, inner lenses, instrument covers and sunroofs; the medical equipment field such as glasses, contact lenses, endoscopic lenses and medical supplies that require sterilization; the construction and building materials field such as road translucent plates, lenses for double glazing, skylights and carports, lighting lenses and lighting covers, and sizing for building materials; and microwave cooking containers (tableware).

[0125] As described above, the film according to the present disclosure has excellent optical properties such as optical homogeneity and transparency. Therefore, by utilizing these optical properties, the film can be particularly suitably used in known optical applications such as optically isotropic films, polarizer protective films, transparent conductive films, and the like, in the periphery of liquid crystal displays.

[0126] Furthermore, the film according to the present disclosure can be attached to a polarizer and used as a polarizing plate. That is, the film can be used as a polarizer protective film for a polarizing plate. The polarizer is not particularly limited, and any conventionally known polarizer can be used. Specific examples include polarizers obtained by incorporating iodine into stretched polyvinyl alcohol.

[0127] (Film manufacturing method) Although one embodiment of the film production method according to the present disclosure will be described, the present invention is not limited thereto. In other words, any conventionally known method can be used as long as it can form the glutarimide resin into a film. Specific examples of the method include injection molding, melt extrusion molding, inflation molding, blow molding, compression molding, etc. The film can also be produced by a solution casting method or spin coating method in which the glutarimide resin is dissolved in a solvent in which it can be dissolved, and then the resulting solution is cast.

[0128] Among these, it is preferable to use a melt extrusion method that does not use a solvent, which can reduce production costs and the burden on the global environment and working environment caused by solvents.

[0129] As one embodiment of the film manufacturing method according to the present disclosure, a method for manufacturing a film by melt extrusion of the glutarimide resin will be described in detail below. In the following description, the film obtained by melt extrusion will be referred to as a "melt-extruded film" to distinguish it from films obtained by other methods such as solution casting.

[0130] When the glutarimide resin is formed into a film by melt extrusion, the glutarimide resin is first fed into an extruder and heated to melt the glutarimide resin.

[0131] The glutarimide resin is preferably pre-dried before being fed to the extruder, as this pre-drying can prevent foaming of the resin extruded from the extruder.

[0132] The method of pre-drying is not particularly limited, but for example, the raw material (i.e., the glutarimide resin) can be made into pellets or the like and pre-drying can be carried out using a hot air dryer, a vacuum dryer, or the like.

[0133] Next, the glutarimide resin that has been heated and melted in the extruder is fed to a T-die via a gear pump and filter. Using a gear pump improves the uniformity of the resin extrusion rate and reduces thickness variations in the longitudinal direction of the film. On the other hand, using a filter removes foreign matter from the glutarimide resin, resulting in a film with a flawless appearance.

[0134] Next, the glutarimide resin supplied to the T-die is extruded from the T-die as a sheet-shaped molten resin, and the sheet-shaped molten resin is then sandwiched between two cooling rolls and cooled to form a film.

[0135] Although there is no particular limitation on the film formation temperature, if the film is formed at a high temperature, the resin viscosity can be reduced, but on the other hand, there is a possibility that the resin may decompose. The film formation temperature is preferably 300°C or less, and more preferably 280°C or less.

[0136] Of the two cooling rolls that sandwich the sheet-like molten resin, it is preferable that one is a rigid metal roll with a smooth surface, and the other is a flexible roll with a smooth surface and an elastically deformable metallic outer sleeve.

[0137] By sandwiching the sheet-like molten resin between such a rigid metal roll and a flexible roll equipped with a metal elastic outer cylinder and cooling it to form a film, minute surface irregularities, die lines, etc. are corrected, and a film with a smooth surface and thickness variation of 5 μm or less can be obtained. In this specification, the term "cooling roll" is used to encompass both "touch roll" and "cooling roll."

[0138] Even when the rigid metal roll and the flexible roll are used, the surfaces of both chill rolls are made of metal, and if the film to be formed is thin, the surfaces of the chill rolls may come into contact with each other, causing scratches on the outer surface of the chill roll or damage to the chill roll itself.

[0139] Therefore, when forming a film by sandwiching a sheet-like molten resin between two chill rolls as described above, it is preferable to first sandwich and cool the sheet-like molten resin between the two chill rolls to obtain a relatively thick raw film, which is then uniaxially or biaxially stretched to produce a film of a predetermined thickness.

[0140] More specifically, when a 40 μm thick film is produced, a sheet-shaped molten resin is sandwiched between the two cooling rolls and cooled to obtain a raw film having a thickness of 150 μm, which is then stretched by longitudinal and transverse biaxial stretching to produce a 40 μm thick film.

[0141] In this way, when the film is a stretched film, the glutarimide resin is first formed into a raw film in an unstretched state, and then the film is stretched uniaxially or biaxially, thereby producing a stretched film.

[0142] In order to improve the flex resistance of the film according to the present disclosure in both the machine direction (MD) and the width direction (TD), it is preferable to carry out biaxial stretching.

[0143] In this specification, for the sake of convenience, the glutarimide resin is formed into a film and then the film is not stretched, that is, the film in an unstretched state is referred to as "raw film."

[0144] When stretching a raw film, the raw film may be continuously stretched immediately after being formed, or the raw film may be stored or moved once after being formed, and then stretched.

[0145] When the raw film is stretched immediately after being formed into a raw film, if the raw film remains in the state of the raw film for a very short time (sometimes even instantaneously) during the film manufacturing process, it does not need to be in a perfect film state as long as it maintains a film shape sufficient for stretching. Furthermore, the raw film does not need to have the properties of a finished film.

[0146] The method for stretching the raw film is not particularly limited, and any conventionally known stretching method may be used. Specifically, for example, transverse stretching using a tenter, longitudinal stretching using rolls, or sequential biaxial stretching, which is a sequential combination of these, may be used. Also, a simultaneous biaxial stretching method in which longitudinal and transverse stretching are performed simultaneously may be used, or a method in which longitudinal roll stretching is performed and then transverse stretching is performed using a tenter may be used.

[0147] When stretching a raw film, it is preferable to first preheat the raw film to a temperature 0.5 to 5°C, preferably 1 to 3°C higher than the stretching temperature, and then cool it to the stretching temperature before stretching.

[0148] By preheating within the above range, the thickness of the raw film in the width direction can be maintained with precision, and the thickness precision of the stretched film does not decrease or thickness unevenness occurs. Furthermore, the raw film does not stick to the roll or sag under its own weight.

[0149] On the other hand, if the preheating temperature of the raw film is too high, problems such as the raw film sticking to the roll or sagging under its own weight tend to occur. Also, if the difference between the preheating temperature of the raw film and the stretching temperature is small, it tends to be difficult to maintain the thickness precision of the raw film before stretching, thickness unevenness tends to increase, and thickness precision tends to decrease.

[0150] In addition, since it is difficult to improve the thickness accuracy of the glutarimide resin by utilizing the necking phenomenon when stretching the raw film after molding, controlling the preheating temperature is useful for maintaining or improving the thickness accuracy of the obtained film.

[0151] The stretching temperature when stretching the raw film is not particularly limited and may be changed depending on the mechanical strength, surface properties, thickness accuracy, etc. required for the stretched film to be produced. Generally, when the glass transition temperature of the raw film (glutarimide resin composition) determined by DSC is Tg, the temperature range is preferably (Tg-30°C) to (Tg+30°C), more preferably (Tg-20°C) to (Tg+30°C), even more preferably (Tg-10°C) to (Tg+30°C), still more preferably (Tg) to (Tg+30°C), and particularly preferably (Tg+10°C) to (Tg+30°C). That is, when the glass transition temperature of the glutarimide resin composition is Tg, the stretching temperature for biaxial stretching of the optical film is preferably in the range of Tg-30°C or higher and Tg+30°C or lower.

[0152] When the stretching temperature is within the above temperature range, thickness unevenness of the resulting stretched film can be reduced, and the mechanical properties of elongation, tear propagation strength, and MIT flex resistance can be improved. Also, problems such as the film sticking to the roll can be prevented.

[0153] On the other hand, if the stretching temperature is higher than the above temperature range, the thickness of the resulting stretched film tends to be uneven, and mechanical properties such as elongation, tear propagation strength, and fatigue resistance tend not to be sufficiently improved. Furthermore, problems such as the film sticking to the rolls tend to occur.

[0154] Furthermore, if the stretching temperature is lower than the above temperature range, the internal haze of the resulting stretched film tends to increase, and in extreme cases, processing problems such as film tearing or cracking tend to occur.

[0155] When the raw film is stretched, the stretching ratio is also not particularly limited and may be determined depending on the mechanical strength, surface properties, thickness accuracy, etc. of the stretched film to be produced. Although it also depends on the stretching temperature, the stretching ratio is generally preferably selected in the range of 1.1 to 3 times, more preferably selected in the range of 1.3 to 2.5 times, and even more preferably selected in the range of 1.5 to 2.3 times.

[0156] If the stretching ratio is within the above range, the mechanical properties of the film, such as elongation, tear propagation strength, and flexural fatigue resistance, can be significantly improved. Therefore, it is possible to produce a stretched film with a thickness variation of 5 μm or less and an internal haze of 1.0% or less.

[0157] When the glutarimide resin according to the present disclosure contains a crosslinked elastic material, the resulting film has excellent mechanical strength, and therefore can be suitably used as any of an unstretched film, a uniaxially stretched film, and a biaxially stretched film.

[0158] (Substrate containing glutarimide resin composition) The glutarimide resin composition according to the present disclosure can be molded into a film and used as a substrate. Because of its excellent dielectric properties, heat resistance, weather resistance, and transparency, the substrate can be used for antennas, vehicle windowpanes, building windowpanes, industrial machine displays, and displays for electronic devices and display devices in homes. Regarding the dielectric properties, for example, when measured at a frequency of 3 GHz, the dielectric loss tangent Df value is preferably 0.010 or less, more preferably 0.007 or less. When the Df value is in this range, loss is low. The relative permittivity Dk value is preferably 3.2 or less, more preferably 3.0 or less.

[0159] When the substrate expands and contracts due to a rise in temperature, the antenna portion formed of a conductor is also pulled by the contraction and expansion of the substrate, causing the antenna dimensions to change. Since the antenna dimensions are uniquely determined by the wavelength of the resonant frequency, it is undesirable for the antenna dimensions to change due to a rise in temperature, etc., so the linear expansion coefficient is preferably 100 ppm or less, and particularly preferably 80 ppm or less. [Example]

[0160] The present invention will be specifically explained below with reference to examples, but the technical scope of the present invention is not limited to these examples.

[0161] (1) M1 and M2 1 Using H-NMR BRUKER AvanceNEO700 (700 MHz), 30 mg of resin was dissolved in 0.75 ml of deuterated DMSO (0.75 ml of deuterated acetone in Example 2), and the 1 H-NMR measurement was performed. M1 and M2 were calculated by the following formula using the value A' obtained by dividing the area A of the peak derived from the O-CH3 proton of methyl methacrylate in the vicinity of 3.5 to 3.8 ppm by 3, the value B' obtained by dividing the area B of the peak derived from the N-CH3 proton of formula (2) in the vicinity of 3.0 to 3.3 ppm by 3, the area C of the peak derived from the NH proton of formula (1) in the vicinity of 10.4 to 10.9 ppm, and the area D of the peak derived from the COOH proton in the vicinity of 12.3 to 12.9 ppm.

[0162] M1=C / (A'+B'+C+D)×100 M2 = B' / (A'+B'+C+D) x 100

[0163] (2) Glass transition temperature (Tg) Using 10 mg of glutarimide resin, a differential scanning calorimeter (DSC, Shimadzu Corporation, Model DSC-50) was used to measure under a nitrogen atmosphere at a heating rate of 20°C / min, and the glass transition temperature was determined by the midpoint method.

[0164] (3) TGA measurement (measurement of 5% thermal loss temperature) Using a thermogravimetric analyzer (TGA: Hitachi High-Tech Science Corporation: STA7200), 15 mg of glutarimide resin was heated from room temperature at a rate of 10°C / min under a nitrogen atmosphere, and the temperature at which the thermal weight loss (wt%) of the glutarimide resin reached 5% was measured.

[0165] (4) Total light transmittance Glutarimide resin was dissolved in methylene chloride (resin concentration: 25% by weight), applied to a PET film, and dried to produce a film. A 50 mm x 50 mm test piece was cut from this film. The total light transmittance of this test piece was measured in accordance with JIS K7105 using a Nippon Denshoku Industries 300A turbidity meter at a temperature of 23°C ± 2°C and a humidity of 50% ± 5%.

[0166] (5) Hayes The haze of the test piece obtained in (4) above was measured using a turbidity meter 300A manufactured by Nippon Denshoku Industries Co., Ltd. at a temperature of 23° C.±2° C. and a humidity of 50%±5% in accordance with JIS K7136.

[0167] (6)(In-plane retardation Re, orientational birefringence) A sample measuring 50 mm wide and 150 mm long was cut from the film prepared in (4) above, and a stretched film was prepared at a stretch ratio of 100% and a temperature 5°C higher than the glass transition temperature. A 40 mm x 40 mm test piece was cut from the center of this uniaxially 2x stretched film in the TD direction. The in-plane retardation Re of this test piece was measured using an automatic birefringence meter (KOBRA-WR manufactured by Oji Measurement Co., Ltd.) at a temperature of 23±2°C, humidity of 50±5%, a wavelength of 590 nm, and an incident angle of 0°. The in-plane retardation Re was divided by the thickness of the test piece measured using a Mitutoyo Digimatic Indicator at a temperature of 23° C.±2° C. and a humidity of 60%±5%, and the value was taken as the orientation birefringence.

[0168] (7) Acid value 0.3 g of glutarimide resin was dissolved in 37.5 mL of methylene chloride, and 37.5 mL of methanol was added. Next, 5 mL of 0.1 mmol% aqueous sodium hydroxide solution and a few drops of phenolphthalein in ethanol were added. Back titration was then performed using 0.1 mmol% hydrochloric acid, and the acid value was calculated from the amount of hydrochloric acid required for neutralization.

[0169] (8) Quantitative determination of acrylate ester units The raw material resin for producing glutarimide resin was subjected to pyrolysis gas chromatography-mass spectrometry (Shimadzu Corporation) at a sample pyrolysis temperature of 590°C, held for 5 seconds, and the amount of acrylic ester units was determined based on the ratio of the area value of methyl methacrylate to the area value of acrylic ester units.

[0170] (9) Weight average molecular weight (Mw) The weight-average molecular weight (Mw) of the resin was calculated by the standard polystyrene conversion method using gel permeation chromatography (GPC). The GPC column was packed with cross-linked polystyrene gel (model: Shodex GPC K-806M, manufactured by Showa Denko K.K.), and chloroform was used as the GPC solvent. The sample solution was prepared by dissolving 5 mg of resin powder in 2 ml of chloroform, and the column temperature was set to 40°C.

[0171] Example 1 Glutarimide resin was produced using a 40mm diameter, fully intermeshing, co-rotating twin-screw extruder. The extruder was a 40mm diameter, co-rotating, intermeshing twin-screw extruder with an L / D (length to diameter ratio) of 90. The raw resin was fed into the extruder's raw material inlet using a constant-weight feeder (Kubota CE-T-2E). The pressure reduction in the extruder's vent was set to -0.10 MPa. The resin (strand) discharged from the extruder was cooled in a cooling water tank and then cut into pellets using a pelletizer. A resin pressure gauge was installed at the extruder outlet to monitor the internal pressure of the extruder and to assess extrusion fluctuations.

[0172] Glutarimide resin was produced using polymethyl methacrylate resin (Mw: 105,000, acrylic ester unit less than 0.1 wt%) as the raw resin and 28 wt% aqueous ammonia as the imidizing agent. The maximum extruder temperature was 280°C, the screw speed was 300 rpm, the raw resin feed rate was 10 kg / hour, and the amount of aqueous ammonia added was 4.0 parts by weight (1.12 parts by weight as pure ammonia) per 100 parts by weight of the raw resin.

[0173] The glutarimide resin had a glass transition temperature of 134.5°C, M1 of 4.3 mol%, M2 of 3.3 mol%, and an acid value of 0.9245 mmol / g. The orientation birefringence was 2.3 × 10 -4 The content of the repeating unit represented by general formula (3) was 87.4 mol %. The evaluation results are shown in Table 1.

[0174] (Comparative Example 1) A glutarimide resin was obtained in the same manner as in Example 1, except that 1.8 parts by weight of methylamine gas was added instead of aqueous ammonia. The evaluation results are shown in Table 1. (Comparative Example 2) The raw material resin, polymethyl methacrylate resin, was subjected to the same evaluation. The evaluation results are shown in Table 1.

[0175] [Table 1]

[0176] From Table 1, it can be seen that the glutarimide resin of Example 1, which contains both the repeating unit represented by formula (1) and the repeating unit represented by formula (2), has a sufficiently low value of orientation birefringence, and also has a higher glass transition temperature and superior heat resistance than the glutarimide resin of Comparative Example 1, which does not contain the repeating unit represented by formula (1), and the polymethyl methacrylate resin of Comparative Example 2.

[0177] Examples 2 to 4 A glutarimide resin was obtained in the same manner as in Example 1, except that liquefied ammonia was added instead of aqueous ammonia in the number of parts shown in Table 2. The evaluation results are shown in Table 2.

[0178] [Table 2]

[0179] From Table 2, it can be seen that the glutarimide resins of Examples 2 to 4, which contain both the repeating unit represented by formula (1) and the repeating unit represented by formula (2) within the range satisfying formula (a), not only have sufficiently low values ​​of orientation birefringence, but also have higher glass transition temperatures and superior heat resistance than the resins of Comparative Examples 1 and 2.

[0180] Furthermore, although 1.8 parts by weight of methylamine was used in Comparative Example 1 and only half that amount of ammonia was used in Example 2, the glutarimide resin of Example 2 had a higher glass transition temperature and better heat resistance than the glutarimide resin of Comparative Example 1. This is thought to be because the glutarimide resin of Comparative Example 1 contains only the repeating unit represented by formula (2), whereas the glutarimide resin of Example 2 contains the repeating unit represented by formula (1) in addition to the repeating unit represented by formula (2).

[0181] In Example 2, the amount of imidization agent used was smaller than in Comparative Example 1, which resulted in a shorter residence time in the extruder, making it easier to increase the discharge rate, and also providing the advantage of being able to reduce the amount of gas emitted during the imidization step.

Claims

1. A repeating unit represented by the following general formula (1): 【Chemistry 1】 (In the formula, R １ and R ２ each independently represents hydrogen or an alkyl group having 1 to 8 carbon atoms. A repeating unit represented by the following general formula (2): 【Chemistry 2】 (In the formula, R ３ and R ４ each independently represents hydrogen or an alkyl group having 1 to 8 carbon atoms. and a repeating unit represented by the following general formula (3): 【Transformation 3】 (In the formula, R ５ and R ６ each independently represents hydrogen or an alkyl group having 1 to 8 carbon atoms; R ７ represents an alkyl group having 1 to 18 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, or a substituent containing an aromatic ring having 5 to 15 carbon atoms. The glutarimide resin satisfies the following formula (a) and has a glass transition temperature of 128°C or higher: 3≦M1+M2≦20 (a) (In the formula, M1 is the content (mol %) of the repeating unit represented by formula (1) in the glutarimide resin, and M2 is the content (mol %) of the repeating unit represented by formula (2) in the glutarimide resin. M1>0 and M2>0.)

2. 2. The glutarimide resin according to claim 1, which has a glass transition temperature of 129.8°C or higher.

3. A glutarimide resin as described in claim 1, having a glass transition temperature of 130°C or higher.

4. 4. The glutarimide resin according to claim 1, wherein the 5% weight loss temperature in TGA measurement is 350° C. or higher.

5. A glutarimide resin described in any one of claims 1 to 4, wherein M2 is 1 mol% or more.

6. A glutarimide resin described in any one of claims 1 to 5, which satisfies the following formula (b): 0.5≦M1 / M2≦2.0 (b)

7. Orientation birefringence is -0.01 × 10 －３ ~2.0 x 10 －３ The glutarimide resin according to any one of claims 1 to 6,

8. A glutarimide resin composition comprising the glutarimide resin according to any one of claims 1 to 7.

9. An optical film comprising the glutarimide resin composition according to claim 8.

10. 10. The optical film according to claim 9, wherein the in-plane retardation Re at a wavelength of 590 nm is 10 nm or less, and the absolute value of the thickness direction retardation Rth is 40 nm or less.

11. A polarizer protective film comprising the optical film according to claim 9 or 10.

12. A substrate comprising the glutarimide resin composition of claim 8.

13. A method for producing a glutarimide resin, comprising a step of reacting a raw material resin, the raw material resin having an acrylic acid ester monomer unit content of less than 1% by weight and having a repeating unit represented by the following general formula (3), with ammonia, wherein the raw material resin is heated to melt and reacted with ammonia at 180 to 300°C: 【Chemistry 4】 (In the formula, R ５ and R ６ each independently represents hydrogen or an alkyl group having 1 to 8 carbon atoms; R ７ represents an alkyl group having 1 to 18 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, or a substituent containing an aromatic ring having 5 to 15 carbon atoms.

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