Method for producing imide structure-containing acrylic resin

Abstract

Provided is a method for producing an imide structure-containing acrylic resin having a structure represented by formula (1), said method comprising a step for heating a starting composition containing a (meth)acrylic polymer, an imidizing agent and an imidization accelerator, wherein: the imidizing agent contains an aromatic amine compound; the imidization accelerator contains at least one selected from the group consisting of ammonia, a primary amine and a secondary amine; and the pKa of the imidization accelerator is 6 or more. In formula (1): R1 and R2 independently represent hydrogen or an alkyl group having 1-8 carbon atoms; and R3 represents an aromatic hydrocarbon group or a heterocyclic aromatic group.

Description

[Technical Field]

[0001] The present invention relates to a method for producing an imide structure-containing acrylic resin. [Background technology]

[0002] Acrylic resins are excellent polymers used in large quantities in a variety of industrial fields due to their excellent transparency, color tone, appearance, weather resistance, gloss, and processability. They are used in a variety of applications, including polarizer protective films for liquid crystal display devices used in mobile phones, smartphones, TVs, and other displays; exterior materials for electrical appliances such as automobile interiors and exteriors; and interior and exterior materials for building materials such as building floors. In recent years, while taking advantage of their excellent optical properties, they have also been expected to be used as insulating substrate materials for high-frequency printed circuits and antenna substrates. As their applications expand, there is a demand for improved heat resistance.

[0003] For example, Patent Document 1 proposes an acrylic resin containing an imide structure having an aromatic group on the nitrogen atom of the imide structure, and discloses that the resin has high heat resistance and low retardation. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-65148 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the present inventors have found that when an aromatic amine compound is used as an imidizing agent, the desired imide structure-containing acrylic resin may not be efficiently imidized in some cases by the production method described in Patent Document 1. There is also room for improvement in yield.

[0006] An object of the present invention is to provide a method for efficiently producing an imide structure-containing acrylic resin when a (meth)acrylic polymer is imidized with an aromatic amine compound. [Means for solving the problem]

[0007] As a result of extensive research, the present inventors have found that when a (meth)acrylic polymer is imidized using an aromatic amine compound as an imidizing agent, the imidization reaction proceeds efficiently by adding at least one imidization accelerator selected from the group consisting of ammonia, primary amines, and secondary amines, and by setting the pKa of the imidization accelerator to 6 or higher.

[0008] (I) A method for producing an imide structure-containing acrylic resin having a structure represented by the following formula (1), comprising a step of heating a raw material composition containing a (meth)acrylic polymer, an imidizing agent, and an imidization accelerator, wherein the imidizing agent contains an aromatic amine compound, the imidization accelerator contains at least one selected from the group consisting of ammonia, a primary amine, and a secondary amine, and the pKa of the imidization accelerator is 6 or more.

[0009] [ka]

[0010] (In formula (1), R 1 and R 2 are each independently a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and R 3 is an aromatic hydrocarbon group or a heteroaromatic group.

[0011] (II) The method for producing an imide structure-containing acrylic resin according to (I), wherein the primary amine has a structure represented by the following formula (2): R 4 NH2(2) (In formula (2), R 4is an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, or an arylalkyl group having 6 to 18 carbon atoms.

[0012] (III) The method for producing an imide structure-containing acrylic resin according to (I), wherein the secondary amine has a structure represented by the following formula (3): HN(R 5 )(R 6 ) (3) (In formula (3), R 5 and R 6 are each independently an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, or an arylalkyl group having 6 to 18 carbon atoms. 5 and R 6 may form a ring structure.)

[0013] (IV) The method for producing an imide structure-containing acrylic resin according to any one of (I) to (III), wherein the imidization accelerator has a pKa of 8 or more.

[0014] (V) The method for producing an imide structure-containing acrylic resin according to any one of (I) to (IV), wherein the imidization accelerator comprises at least one selected from the group consisting of ammonia, methylamine, ethylamine, diethylamine, dimethylamine, N-methylethylamine, N-methylpropylamine, N-methylbutylamine, pyrrolidine, and piperidine.

[0015] (VI) The method for producing an imide structure-containing acrylic resin according to any one of (I) to (V), wherein the imidizing agent contains at least one selected from the group consisting of aniline, toluidine, anisidine, aminopyridine, aminobiphenyl, and aminonaphthalene.

[0016] (VII) The method for producing an imide structure-containing acrylic resin according to any one of (I) to (VI), wherein the content of the imidization accelerator in the raw material composition is 1 to 80 parts by weight per 100 parts by weight of the (meth)acrylic polymer.

[0017] (VIII) The method for producing an imide structure-containing acrylic resin according to any one of (I) to (VII), wherein the raw material composition contains 0.1 mol to 10 mol of the imidization accelerator per 1 mol of the imidizing agent.

[0018] (IX) The method for producing an imide structure-containing acrylic resin according to any one of (I) to (VIII), wherein the content of the imidizing agent in the raw material composition is 1 to 100 parts by weight per 100 parts by weight of the (meth)acrylic polymer.

[0019] (X) The method for producing an imide structure-containing acrylic resin according to any one of claims (I) to (IX), wherein the (meth)acrylic polymer contains a methacrylic acid alkyl ester unit.

[0020] (XI) The method for producing an imide structure-containing acrylic resin according to (X), wherein the methacrylic acid alkyl ester unit has an alkyl group having 1 to 8 carbon atoms.

[0021] (XII) The method for producing an imide structure-containing acrylic resin according to (X) or (XI), wherein the (meth)acrylic polymer has a content of the methacrylic acid alkyl ester units of 50% by weight or more based on the total amount of the (meth)acrylic polymer.

[0022] (XIII) A method for producing the imide structure-containing acrylic resin according to any one of (I) to (XII), comprising a step of mixing a mixture of the imidization accelerator and the imidizing agent with the (meth)acrylic polymer.

[0023] (XIV) The method for producing an imide structure-containing acrylic resin according to any one of (I) to (XIII), wherein the temperature in the step of heating the raw material composition containing the (meth)acrylic polymer, the imidizing agent, and the imidization accelerator is 180°C to 320°C.

[0024] (XV) The method for producing an imide structure-containing acrylic resin according to any one of (I) to (XIV), wherein the pressure in the step of heating the raw material composition containing the (meth)acrylic polymer, the imidizing agent, and the imidization accelerator is 0.1 MPa to 50 MPa. [Effects of the Invention]

[0025] According to the present invention, it is possible to provide a method for efficiently producing an imide structure-containing acrylic resin when a (meth)acrylic polymer is imidized with an aromatic amine compound. DETAILED DESCRIPTION OF THE INVENTION

[0026] Hereinafter, an embodiment of the present invention will be described.

[0027] The method for producing the imide structure-containing acrylic resin of the present embodiment includes a step of heating a raw material composition containing a (meth)acrylic polymer, an imidizing agent, and an imidization accelerator.

[0028] (i) (meth)acrylic polymer The (meth)acrylic polymer is a polymer obtained mainly by polymerizing acrylic acid, methacrylic acid, and derivatives thereof, and is not particularly limited as long as the effects of the present invention are not impaired, and any known (meth)acrylic polymer can be used. For example, the (meth)acrylic polymer can be produced by polymerizing a monomer composition containing a (meth)acrylic acid ester as a main component.

[0029] Examples of (meth)acrylic acid esters include (meth)acrylic acid alkyl esters such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, and isobutyl (meth)acrylate, as well as aryl (meth)acrylates, alkylaryl (meth)acrylates, and alicyclic alkyl (meth)acrylates having 6 to 12 carbon atoms such as phenyl (meth)acrylate, benzyl (meth)acrylate, and cyclohexyl (meth)acrylate. These may be used alone or in combination of two or more.

[0030] From the viewpoint of improving the heat resistance of the resulting imide structure-containing acrylic resin, the (meth)acrylic polymer preferably contains a methacrylic acid alkyl ester unit.

[0031] Furthermore, since an imide structure-containing acrylic polymer can be efficiently produced, the (meth)acrylic polymer preferably contains a (meth)acrylic acid alkyl ester unit having an alkyl group having 1 to 8 carbon atoms, and among these, a methyl (meth)acrylate unit, an ethyl (meth)acrylate unit, an n-propyl (meth)acrylate unit, or an n-butyl (meth)acrylate unit is more preferred, with a methyl (meth)acrylate unit being particularly preferred.

[0032] The content of (meth)acrylic acid alkyl ester units in the (meth)acrylic polymer is not particularly limited, but from the viewpoint of heat resistance, it is preferably 50% by weight or more, more preferably 75% by weight or more, and particularly preferably 90% by weight or more.

[0033] To further improve the heat resistance of the resulting imide structure-containing acrylic resin, a (meth)acrylic polymer having a ring structure in the main chain may be used. Examples of the ring structure include a lactone ring structure, a maleic anhydride structure, a glutaric anhydride structure, a maleimide structure, and a glutarimide structure represented by the following formula (1):

[0034] [ka]

[0035] (In the formula (1), R 1 and R 2 each independently represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and R 3 is a hydrogen atom, an alkyl group having 1 to 18 carbon atoms, or a cycloalkyl group having 3 to 12 carbon atoms.

[0036] The method for introducing a ring structure into the main chain of a (meth)acrylic polymer includes known methods. Examples of (meth)acrylic polymers having a lactone ring structure include those described in JP-A-2004-168882 and JP-A-2006-171464, etc. Examples of (meth)acrylic polymers having a maleimide structure include (meth)acrylic polymers having N-substituted maleimide units as described in JP-A-2007-31537, and examples of (meth)acrylic polymers containing glutaric anhydride structures include those described in JP-A-2004-70296, JP-A-2004-307834, JP-A-2008-74918, WO 2007 / 26659, etc.

[0037] The glass transition temperature (Tg) of the (meth)acrylic polymer having a ring structure in the main chain is not particularly limited, but is preferably at least 110° C., more preferably at least 115° C., and particularly preferably at least 120° C. If the glass transition temperature is below this range, the heat resistance of the molded article will be poor, resulting in significant changes in physical properties at high temperatures and a narrower range of application.

[0038] The content of the ring structure in the (meth)acrylic resin having a ring structure in the main chain is not particularly limited, but is not particularly limited as long as it is 2% by weight or more in consideration of the balance between heat resistance and physical properties, and is more preferably 2.5% by weight or more. The upper limit is not particularly limited as long as moldability is possible, and can be appropriately selected in consideration of the balance with physical properties, but is preferably 70% by weight or less, more preferably 50% by weight or less, and particularly preferably 30% by weight or less.

[0039] In addition to the above-mentioned monomers, 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 may also be included.

[0040] The structure of the (meth)acrylic polymer 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 an AB type, an ABC type, an ABA type, or a type other than these. In the case of a core-shell polymer, it may be composed of only one layer of core and one layer of shell, or each may be composed of multiple layers.

[0041] (ii) Imidizing agent The imidizing agent is not particularly limited as long as it is an aromatic amine compound capable of producing the glutarimide unit represented by the general formula (1). Here, the aromatic amine compound refers to an organic compound in which hydrogen atoms in an aromatic ring are replaced with amino groups, and the aromatic ring may be a heteroaromatic ring containing atoms other than carbon. Specific examples include aniline, toluidine, anisidine, xylidine, trimethylaniline, trichloroaniline, aminopyridine, aminobiphenyl, aminonaphthalene, aminoanthracene, and aminotetracene. These may be used alone or in combination of two or more.

[0042] The aromatic ring of the aromatic amine compound preferably has 5 to 18 atoms, more preferably 5 to 10 atoms, because this provides good reaction efficiency and good physical properties for the resulting imide structure-containing acrylic resin.

[0043] Among the imidizing agents exemplified above, one or more selected from aniline, toluidine, anisidine, xylidine, aminopyridine, aminobiphenyl, and aminonaphthalene are preferred because of their good reactivity with the (meth)acrylic polymer and the good heat resistance of the resulting imide structure-containing acrylic resin, and one or more selected from aniline, toluidine, anisidine, and xylidine are more preferred, with aniline being particularly preferred because of its excellent balance between cost and physical properties.

[0044] In this imidization step, the proportion of glutarimide units in the resulting imide structure-containing acrylic resin can be adjusted by adjusting the proportion of the imidization agent added.

[0045] Furthermore, by adjusting the degree of imidization, it is possible to adjust the physical properties of the resulting imide structure-containing acrylic resin and the optical properties of an optical film obtained by molding a resin composition containing the imide structure-containing acrylic resin.

[0046] The content of the imidizing agent in the raw material composition can be adjusted appropriately depending on the required properties. For example, it can be adjusted appropriately depending on the required properties as long as it is 1 part by weight or more relative to 100 parts by weight of the (meth)acrylic polymer, and 4 parts by weight or more is more preferred. If it is less than 1 part by weight, the heat resistance of the resulting resin composition containing the imide structure-containing acrylic resin may decrease. The upper limit can be selected appropriately in relation to moldability and physical properties, but from the perspective of ease of handling, it is preferably 100 parts by weight or less, more preferably 80 parts by weight or less, and even more preferably 70 parts by weight or less.

[0047] (iii) Imidization accelerator The imidization accelerator in this embodiment contains at least one selected from the group consisting of ammonia, primary amines, and secondary amines, and is not particularly limited as long as it has a pKa of 6 or greater.

[0048] The primary amine preferably has a structure represented by the following formula (2): R 4 NH2(2) (In formula (2), R 4 is an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, or an arylalkyl group having 6 to 18 carbon atoms.

[0049] Specific examples include linear or branched alkylamines such as methylamine, ethylamine, n-propylamine, isopropylamine, n-butylamine, and n-hexylamine; cycloalkylamines such as cyclopropylamine, cyclobutylamine, cyclopentylamine, and cyclohexylamine; and arylalkylamines such as benzylamine and phenethylamine.

[0050] The secondary amine preferably has a structure represented by the following formula (3): HN(R 5 )(R 6 ) (3) (In formula (3), R 5 and R 6 are each independently an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, or an arylalkyl group having 6 to 18 carbon atoms. 5 and R 6 may form a ring structure.)

[0051] Specific examples include linear or branched dialkylamines such as dimethylamine, diethylamine, N-methylethylamine, N-methylpropylamine, N-methylbutylamine, and diisopropylamine; alicyclic amines such as pyrrolidine, piperidine, and morpholine; dicyclohexylamine; and dibenzylamine.

[0052] As the imidization accelerator, ammonia, methylamine, ethylamine, diethylamine, dimethylamine, N-methylethylamine, N-methylpropylamine, N-methylbutylamine, pyrrolidine and piperidine are preferred.

[0053] Although ammonia and primary amines are the aforementioned imidization accelerators, they themselves may react with the (meth)acrylic polymer to form an imide structure. Therefore, from the viewpoint of minimizing side reactions and obtaining the desired imide structure-containing acrylic resin, secondary amines such as diethylamine, dimethylamine, N-methylethylamine, N-methylpropylamine, N-methylbutylamine, pyrrolidine, and piperidine are more preferred, and N-methylpropylamine, diethylamine, and dimethylamine are particularly preferred.

[0054] The pKa of the imidization accelerator is not particularly limited as long as it is 6 or more, but is preferably 8 or more, more preferably 9 or more, and particularly preferably 10 or more, because it is highly effective in promoting imidization. The upper limit is not particularly limited, but is, for example, preferably 14 or less, more preferably 13 or less. Here, pKa is a value defined by the following formula. pKa=-log 10 Ka Furthermore, AH→A - +H + The acid dissociation constant (Ka) in the reaction is Ka = [A - ][H + ] / [AH] is the value calculated.

[0055] The content of the imidization accelerator in the raw material composition can be adjusted appropriately depending on the required properties. For example, it is sufficient to use 1 part by weight or more, and more preferably 3 parts by weight or more, per 100 parts by weight of the (meth)acrylic polymer. If the content is less than 1 part by weight, the effect of promoting imidization is small, and an imide structure-containing acrylic resin having the desired imidization rate may not be obtained. The upper limit can be selected appropriately in relation to moldability and physical properties. From the viewpoints of ease of handling and preventing deterioration of the mechanical properties of molded articles due to residual imidization accelerator, it is preferably 80 parts by weight or less, more preferably 60 parts by weight or less, and particularly preferably 40 parts by weight or less.

[0056] The content of the imidization accelerator in the raw material composition is preferably 0.1 to 10 moles per mole of the imidizing agent. From the viewpoint of promoting efficient imidization and improving the yield of the imide structure-containing acrylic resin, the lower limit is preferably 0.5 moles or more, and particularly preferably 0.8 moles or more. The upper limit is preferably 10 moles or less, more preferably 5 moles or less, and particularly preferably 3 moles or less.

[0057] (iv) Imide structure-containing acrylic resin The imide structure-containing acrylic resin of the present embodiment contains a structure represented by the following general formula (1).

[0058] [ka]

[0059] (In formula (1), R 1 and R 2 are each independently a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and R 3 is an aromatic hydrocarbon group or a heteroaromatic group.

[0060] In the structure represented by the formula (1), R 1 and R 2 are each independently a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. Examples of alkyl groups having 1 to 8 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a t-butyl group, an n-hexyl group, an n-octyl group, and a 2-ethylhexyl group. Among these, a hydrogen atom or an alkyl group having 1 to 4 carbon atoms is preferred because of its excellent heat resistance.

[0061] In the structure represented by the formula (1), R 3is an aromatic hydrocarbon group or a heteroaromatic group. The number of atoms constituting the aromatic ring is preferably 5 to 18, and more preferably 5 to 10. Specific examples include a phenyl group, a tolyl group, anisyl group, a xylyl group, a trimethylphenyl group, a trichlorophenyl group, a pyridyl group, a biphenyl group, a naphthyl group, and an anthryl group. Among these, phenyl group, tolyl group, anisyl group, xylyl group, pyridyl group, biphenyl group, and naphthyl group are preferred because of their excellent heat resistance, and phenyl group, tolyl group, anisyl group, and xylyl group are more preferred.

[0062] The imide structure-containing acrylic resin may contain two or more types of structures represented by the formula (1).

[0063] The weight average molecular weight of the imide structure-containing acrylic 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, there is no decrease in molding processability, and there is no shortage of mechanical strength during film processing.

[0064] The glass transition temperature of the imide structure-containing acrylic resin is not particularly limited, but is preferably 120°C or higher, more preferably 125°C or higher, even more preferably 130°C or higher, and particularly preferably 135°C or higher. If the temperature is below this range, the heat resistance of the molded article or film will be poor, resulting in significant changes in physical properties at high temperatures and a narrower range of application. The glass transition temperature can be determined, for example, by using 10 mg of resin and measuring it using a differential scanning calorimeter (DSC, Shimadzu Corporation DSC-50 model) in a nitrogen atmosphere at a heating rate of 20°C / min, using the midpoint method.

[0065] The imidization rate of the imide structure-containing acrylic resin can be adjusted appropriately depending on the required properties and is not particularly limited. However, since heat resistance is improved, the lower limit of the imidization rate is preferably 10% or more, more preferably 15% or more, and particularly preferably 20% or more. Furthermore, from the viewpoint of preventing deterioration of handleability due to an increase in viscosity, the upper limit is preferably 80% or less, more preferably 75% or less, and particularly preferably 70% or less. Within the above range, a resin composition with an excellent balance between heat resistance and viscosity can be obtained. The imidization rate of the imide structure-containing acrylic resin can be determined by the method described below.

[0066] The imidization rate of the imide structure-containing acrylic resin can be determined by measuring the IR spectrum using a Fourier transform infrared spectrophotometer (JASCO FI / IR-4100). -1 The absorption due to the ester carbonyl group in the vicinity and the absorption at 1680cm -1 The imidization rate is determined from the intensity ratio of the absorption due to the imide carbonyl group to the absorption due to the imide carbonyl group in the vicinity of the ester carbonyl group. Here, the imidization rate is the proportion of the imide carbonyl group in the total of the ester carbonyl group and the imide carbonyl group.

[0067] The acid value of the imide structure-containing acrylic resin represents the content of carboxylic acid units and acid anhydride units in the imide structure-containing acrylic resin. The acid value can be calculated, for example, by the titration method described in International Publication No. 2005 / 054311. The acid value of the imide structure-containing acrylic resin in this embodiment is preferably 0.10 to 1.00 mmol / g. If the acid value is within the above range, an imide structure-containing acrylic resin having an excellent balance of heat resistance, mechanical properties, and moldability can be obtained.

[0068] In particular, the content of carboxylic acid among the acid components is preferably 0.25 mmol / g or less, more preferably 0.20 mmol / g or less, from the viewpoint of molding processability.

[0069] 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, the amount of carboxylic acid can be calculated using the formula (Amount of carboxylic acid) = 2 × (Acid value) - (DMSO acid value) The above formula can be applied because in titration with methanol, the acid anhydride is counted as one molecule, whereas in titration with dimethyl sulfoxide, the acid anhydride is counted as two molecules.

[0070] From the viewpoint of thermal stability, the content of acrylic ester units contained in the imide structure-containing acrylic resin in this embodiment 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 acrylic ester units are contained.

[0071] In addition, the imide structure-containing acrylic resin in this embodiment has an orientation birefringence value of −0.5×10 -3 ~0.5×10 -3 is preferably -0.25 x 10 -3 ~0.25×10 -3 It is more preferable that:

[0072] If the orientation birefringence is within the above range, birefringence will not occur during molding even when the environment changes, and stable optical properties can be obtained.

[0073] In this specification, unless otherwise specified, the term "orientation birefringence" refers to the birefringence that appears when the thermoplastic resin is stretched 100% at a temperature 5°C higher than the glass transition temperature. Orientation birefringence (Δn) is expressed by the formula △n=nx-ny=Re / d and can be measured using a retardation meter. In the above formula, nx and ny represent the refractive index in the X-axis direction and the Y-axis direction, respectively, 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. Furthermore, Re represents the in-plane retardation, and d represents the thickness of the film.

[0074] The photoelastic coefficient of the imide structure-containing acrylic resin 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 ratio is 1 / N or less.

[0075] The absolute value of the photoelastic coefficient is 20 x 10 -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.

[0076] When an external force is applied to an isotropic solid to cause stress (ΔF), it temporarily exhibits optical anisotropy and birefringence (Δn). The ratio of the stress to birefringence is called the photoelastic coefficient (c), and is expressed by the formula: c=Δn / ΔF It is shown as follows.

[0077] In this embodiment, the photoelastic coefficient is a value measured by the Senarmont method at a wavelength of 515 nm at 23° C. and 50% RH.

[0078] (v) Method for producing imide structure-containing acrylic resin The method for producing an imide structure-containing acrylic resin according to the present embodiment includes a step (imidization step) of heating a raw material composition containing a (meth)acrylic polymer, an imidizing agent, and an imidization accelerator, thereby producing an imide structure-containing acrylic resin.

[0079] The treatment method in the imidization step is not particularly limited, and any conventionally known method can be used. For example, the (meth)acrylic polymer can be imidized to form an imide structure-containing acrylic resin by a method in which the (meth)acrylic polymer is reacted while being heated and melted using an extruder, a batch-type reaction tank (pressure vessel), etc.

[0080] When the raw material composition containing the (meth)acrylic polymer, the imidizing agent, and the imidization accelerator is processed by heating and melting the raw material composition using an extruder, the extruder 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, or the like can be used.

[0081] Among these, it is preferable to use a twin-screw extruder, which can promote mixing of the imidizing agent and the imidization accelerator with the (meth)acrylic polymer.

[0082] 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 imidizing agent and the imidization accelerator with the (meth)acrylic polymer.

[0083] The method for mixing the (meth)acrylic polymer, the imidizing agent, and the imidization accelerator is not particularly limited, but the imidizing agent and the imidization accelerator may be mixed in advance and then mixed with the (meth)acrylic polymer, or the imidizing agent and the imidization accelerator may be mixed separately. In this case, the imidizing agent may be mixed first, or the imidization accelerator may be mixed first.

[0084] 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.

[0085] When imidization is carried out in an extruder, for example, a (meth)acrylic polymer as a raw material resin is charged into a raw material charging port of the extruder, the resin is melted, and the cylinder is filled with the resin. Then, a mixture of an imidization agent and an imidization accelerator is injected into the extruder using an addition pump, thereby allowing the imidization reaction to proceed in the extruder.

[0086] In this case, imidization is preferably carried out at a reaction zone temperature (resin temperature) in the extruder of 180°C to 320°C, and more preferably at 220 to 300°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 320°C, decomposition of the resin becomes significant, and the flex resistance of the film that can be formed from the resulting imide structure-containing acrylic 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 imidizing agent and the resin discharge port (die portion).

[0087] 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.

[0088] The resin pressure in the extruder is preferably in the range of 0.1 MPa to 50 MPa, more preferably in the range of 1 MPa to 30 MPa. If it is less than 0.1 MPa, the solubility of the imidizing agent is low, and the progress of the reaction tends to be inhibited. If it is more than 50 MPa, the mechanical pressure limit of a normal extruder is exceeded, and special equipment is required, which is undesirable from the viewpoint of cost.

[0089] When an extruder is used, it is preferable to equip it with a vent hole that can reduce the pressure to atmospheric pressure or below in order to remove unreacted imidizing agent, imidization accelerator, and by-products. With such a configuration, it is possible to remove unreacted imidizing agent, imidization accelerator, or by-products and monomers such as methanol and tertiary amines.

[0090] In addition, in place of an extruder, a reaction apparatus capable of handling high viscosity, 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 for producing the imide structure-containing acrylic resin.

[0091] When the imide structure-containing acrylic resin is produced using a batch-type reaction vessel (pressure vessel), the structure of the batch-type reaction vessel (pressure vessel) is not particularly limited.

[0092] Specifically, the (meth)acrylic polymer may have a structure that allows it to be melted by heating and stirred, and that allows the imidizing agent and the imidization accelerator to be added, but it is preferable that the structure has good stirring efficiency.

[0093] Such a batch-type reaction tank (pressure vessel) can prevent the resin 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.

[0094] Specific examples of the imidization method include known methods such as those described in JP-A Nos. 2008-273140 and 2008-274187.

[0095] (Esterification step) The method for producing an imide structure-containing acrylic resin according to the present embodiment can include a step of treating with an esterifying agent in addition to the imidization step, which allows the acid value of the imide structure-containing acrylic 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.

[0096] In this esterification step, the amount of the esterifying agent is preferably 0 to 12 parts by weight, more preferably 0 to 8 parts by weight, based on 100 parts by weight of the (meth)acrylic polymer.

[0097] 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.

[0098] In addition to the esterifying agent, a catalyst can also be used in combination. 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.

[0099] In this esterification step, only a heat treatment or the like can be performed without treatment with an esterifying agent. When only a 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 by a dehydration reaction between carboxylic acids in the imide structure-containing acrylic resin produced as a by-product in the imidization step and / or a dealcoholization reaction between the carboxylic acid and an alkyl ester group. In this case, the aforementioned catalyst can also be used.

[0100] Even when the treatment is carried out with an esterifying agent, it is possible to promote the formation of acid anhydride groups by heat treatment.

[0101] (devolatilization process, filtration process) The imide structure-containing acrylic resin that has undergone the imidization step and the esterification step contains unreacted imidization agent, imidization accelerator, esterification agent, volatile components by-produced by the reaction, resin decomposition products, etc., and therefore, it is possible to equip the resin with a vent hole that can reduce the pressure to below atmospheric pressure.

[0102] Furthermore, a filter can be installed at the end of the extruder to reduce foreign matter in the imide structure-containing acrylic resin. A gear pump is preferably installed before the filter to increase the pressure of the imide structure-containing acrylic resin. The type of filter 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.

[0103] (vi) Imide structure-containing acrylic resin composition To the imide structure-containing acrylic resin of this embodiment, commonly used weathering stabilizers such as antioxidants, heat stabilizers, light stabilizers, ultraviolet absorbers, and radical scavengers, as well as catalysts, plasticizers, lubricants, antistatic agents, colorants, shrinkage inhibitors, antibacterial and deodorizing agents, etc. may be added singly or in combination of two or more, as needed, within the scope that does not impair the object of the present invention, to form an imide structure-containing acrylic resin composition. Furthermore, these additives can also be added when the imide structure-containing acrylic resin is molded and processed.

[0104] The imide structure-containing acrylic resin composition of this embodiment preferably contains an ultraviolet absorber. The imide structure-containing acrylic resin composition of this embodiment 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.

[0105] The ultraviolet absorber has a maximum absorption wavelength of 300 nm or more and 370 nm or less. When exposed to ultraviolet light, an imide structure-containing acrylic 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, the amount of ultraviolet absorber added can be relatively small, and bleed-out due to an increase in the amount of ultraviolet absorber is unlikely to occur.

[0106] Furthermore, the ultraviolet absorber 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 mold (roll, etc.) contamination 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.

[0107] Examples of ultraviolet absorbers using such triazine compounds include Tinuvin 1577, Tinuvin 460, Tinuvin 477, Tinuvin 479 (all manufactured by BASF), and LA-F70 (manufactured by ADEKA).

[0108] In the case where the imide structure-containing acrylic resin composition of the present embodiment 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, relative to 100 parts by weight of the imide structure-containing acrylic resin.

[0109] 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.

[0110] (vii) Other Components Included in the Imide Structure-Containing Acrylic Resin Composition The imide structure-containing acrylic resin composition may contain a crosslinked elastomer to improve the mechanical strength of the imide structure-containing acrylic 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.

[0111] 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.

[0112] 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 mechanical strength of the imide structure-containing acrylic resin may not be sufficiently improved. 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 imide structure-containing acrylic resin may be reduced.

[0113] In this specification, 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).

[0114] 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% by weight, preferably 0 to 45% by weight, more preferably 10 to 40% by weight, relative to the total amount of the core layer (100% by weight). 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.

[0115] The core-shell type elastomer may contain any other appropriate component within the range that does not impair the effects of the present invention.

[0116] As the polymerizable monomer for forming the rubber polymer constituting the core layer, any appropriate polymerizable monomer may be used.

[0117] 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, of the polymerizable monomers (100% by weight) forming the rubbery polymer.

[0118] 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.

[0119] The polymerizable monomers forming the rubber 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 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.

[0120] 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.

[0121] 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 polymerizable monomers forming the rubber-like polymer preferably contain 0 to 49.9 wt %, more preferably 0 to 39.9 wt %, of the other polymerizable monomers.

[0122] Examples of the other polymerizable monomers include aromatic vinyls such as styrene, vinyl toluene, and α-methylstyrene, aromatic vinylides, vinyl cyanides such as acrylonitrile and methacrylonitrile, vinylidene cyanide, methyl methacrylate, urethane acrylate, and urethane methacrylate. 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.

[0123] 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.

[0124] 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.

[0125] 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 (100% by weight) 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.

[0126] The alkyl (meth)acrylate is preferably one in which the alkyl group has 1 to 8 carbon atoms. 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.

[0127] 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.

[0128] The polymerizable monomers forming 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, of the polymerizable monomers (100% by weight) forming the glassy polymer.

[0129] Specific examples of the polyfunctional monomer having two or more polymerizable functional groups in the molecule include the same as those mentioned above.

[0130] 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, of the polymerizable monomers (100% by weight) forming the glassy polymer.

[0131] 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 acrylates, and urethane methacrylates. Furthermore, the monomers may have functional groups such as epoxy groups, carboxyl groups, hydroxyl groups, and amino groups. 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-hydroxymethacrylate and 2-hydroxyacrylate; and examples of monomers having amino groups include diethylaminoethyl methacrylate and diethylaminoethyl acrylate. These monomers may be used alone or in combination of two or more.

[0132] Furthermore, it is also preferred that the polymerizable monomer for forming the glassy polymer is used in combination with a small amount of a known chain transfer agent, similar to that used in the rubbery polymer layer.

[0133] As a method for producing the core-shell type elastomer in this embodiment, any appropriate method capable of producing core-shell type particles can be adopted.

[0134] 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.

[0135] Preferred structures of the core-shell type elastomer include, for example, (a) one 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) one having a multilayer structure in which the rubbery core layer has one or more glassy layers therein and further having a glassy shell layer outside the core layer. By appropriately selecting the type of monomer for each layer, the physical properties of the imide structure-containing acrylic resin can be controlled as desired.

[0136] Specific examples of more preferred structures of the core-shell type elastomer include, for example, (A) the shell layer of the core-shell type elastomer 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) the shell layer of the core-shell type elastomer is composed 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) the core layer of the core-shell type elastomer is composed 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; 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 (D) a multilayer structure in which a core layer of the above-mentioned core-shell elastomer is formed by polymerizing a rubbery polymer layer using a peracid (persulfuric acid, perphosphate, etc.) 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. Having such a structure facilitates good dispersion of the core-shell elastomer in the imide structure-containing acrylic resin of this embodiment, 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 and stress, resulting in a high-quality film.

[0137] When the core-shell elastomer of this embodiment 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, t-butyl hydroperoxide, and 1,1-dimethyl-2-hydroxyethyl hydroperoxide; peresters such as t-butyl isopropyloxycarbonate and t-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 selected appropriately depending on the composition of the monomers to be polymerized, the layer structure, the polymerization temperature conditions, and the like.

[0138] When the core-shell elastomer of this embodiment 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.

[0139] When the imide structure-containing acrylic resin composition of this embodiment contains a core-shell type elastomer, the content of the core-shell type 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, relative to 100 parts by weight of the imide structure-containing acrylic resin. If the content of the core-shell type elastomer is less than 1 part by weight, the improvement in mechanical strength of the imide structure-containing acrylic resin is insufficient, and if it exceeds 40 parts by weight, the heat resistance of the imide structure-containing acrylic resin may be reduced.

[0140] 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 mechanical strength of the imide structure-containing acrylic resin will not be sufficiently improved, and if it is greater than 500 nm, the heat resistance and transparency of the imide structure-containing acrylic resin may be impaired.

[0141] 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.

[0142] (viii) Film containing an imide structure-containing acrylic resin composition The imide structure-containing acrylic resin composition can be formed into a film containing the imide structure-containing acrylic resin composition by, for example, a known molding method.

[0143] The haze value of the film containing the imide structure-containing acrylic resin composition is preferably 2.0% or less, more preferably 1.0% or less. The transmittance is preferably 85% or more, more preferably 90% or more. It is preferable that both the haze value and the transmittance are within the above ranges, as this broadens the range of applications in which the film can be used.

[0144] Although there are no particular limitations 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 are small. 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 particularly preferably 1 nm or less. Furthermore, the thickness direction retardation is preferably 40 nm or less, more preferably 15 nm or less, and even more preferably 3 nm or less.

[0145] The in-plane retardation (Re) and the thickness direction retardation (Rth) can be calculated by the following formulas. Re=(nx-ny)×d Rth=|(nx+ny) / 2-nz|×d In the above 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 film thickness, and || represents the absolute value.

[0146] The film obtained from the imide structure-containing acrylic resin composition of this embodiment has a small 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 amount of the foreign matter is less than 1 m. 2 The number of foreign particles larger than 20 μm was counted using a microscope, and the total number of foreign particles was calculated.

[0147] Films containing the imide structure-containing acrylic resin composition of this embodiment 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 replacement films, glass substrate replacement films, 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, back covers for smartphones, release films, and detector substrates for X-ray inspection equipment.

[0148] 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).

[0149] As described above, the film of the present embodiment 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.

[0150] Furthermore, the film of the present embodiment can be attached to a polarizer and used as a polarizing plate. That is, the film of the present embodiment 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.

[0151] (Film manufacturing method) An example of a method for producing a film containing the imide structure-containing acrylic resin composition of the present embodiment will be described below, but the method for producing the film of the present embodiment is not limited to this. In other words, the method for producing the film of the present embodiment can be any conventionally known method as long as it is a method that can produce a film by molding the imide structure-containing acrylic resin of the present embodiment.

[0152] Specific examples of such methods include injection molding, melt extrusion molding, inflation molding, blow molding, and compression molding. Furthermore, the film of this embodiment can be produced by a solution casting method or spin coating method, in which the imide structure-containing acrylic resin of this embodiment is dissolved in a solvent capable of dissolving the resin and then molding the resulting solution. Among these, the melt extrusion method, which does not use a solvent, is preferred. The melt extrusion method can reduce production costs and the burden on the global environment and working environment caused by solvents.

[0153]

[0033] Hereinafter, as an example of a method for producing a film in this embodiment, a method for producing a film by melt extrusion of the imide structure-containing acrylic resin in this embodiment will be described in detail. In the following description, the film obtained by the melt extrusion method will be referred to as a "melt-extruded film" to distinguish it from films obtained by other methods such as solution casting.

[0154] When the imide structure-containing acrylic resin of this embodiment is formed into a film by melt extrusion, first, the imide structure-containing acrylic resin of this embodiment is fed to an extruder and heated to melt the imide structure-containing acrylic resin.

[0155] The imide structure-containing acrylic resin is preferably pre-dried before being fed to the extruder. Such pre-drying can prevent foaming of the resin extruded from the extruder. The pre-drying method is not particularly limited, but for example, the raw material (i.e., the imide structure-containing acrylic resin in this embodiment) can be made into a form such as pellets and then pre-dried using a hot air dryer, a vacuum dryer, or the like.

[0156] Next, the imide structure-containing acrylic resin that has been heated and melted in the extruder is fed to a T-die through a gear pump and a 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 imide structure-containing acrylic resin, resulting in a film with a defect-free and excellent appearance.

[0157] Next, the imide structure-containing acrylic resin supplied to the T-die is extruded from the T-die as a sheet-like molten resin. The sheet-like molten resin is then sandwiched between two cooling rolls and cooled to form a film. Of the two cooling rolls sandwiching the sheet-like molten resin, one is preferably a rigid metal roll with a smooth surface, and the other is preferably a flexible roll equipped with a smooth, elastically deformable metallic outer sleeve.

[0158] By sandwiching the sheet-like molten resin between such a rigid metal roll and a flexible roll equipped with an elastic metal outer cylinder, cooling it, and forming it into a film, minute surface irregularities and die lines, etc. are corrected, resulting in a film with a smooth surface and thickness variation of 5 μm or less.

[0159] In this specification, the term "cooling roll" is used to include "touch roll" and "cooling roll".

[0160] Even when the above-mentioned rigid metal roll and flexible roll are used, the surfaces of both chill rolls are metal, so 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.

[0161] 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.

[0162] 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.

[0163] In this way, when the film in the present embodiment is a stretched film, the imide structure-containing acrylic resin in the present embodiment is first formed into a raw film in an unstretched state, and then the raw film is subjected to uniaxial stretching or biaxial stretching, thereby producing a stretched film.

[0164] In order to improve the bending resistance of the optical film in this embodiment in both the machine direction (MD) and the width direction (TD), it is preferable to perform biaxial stretching.

[0165] In this specification, for the sake of convenience, the film obtained by forming the imide structure-containing acrylic resin of this embodiment into a film and then before stretching it, i.e., the film in an unstretched state, will be referred to as a "raw film."

[0166] 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.

[0167] 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.

[0168] (Film stretching method) 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, and sequential biaxial stretching, which is a sequential combination of these, may be used.

[0169] Alternatively, a simultaneous biaxial stretching method in which longitudinal and transverse stretching are performed simultaneously, or a method in which longitudinal roll stretching is performed and then transverse stretching is performed using a tenter, can also be used. When stretching a raw film, it is preferable to first preheat the raw film to a temperature 0.5°C to 5°C, preferably 1°C to 3°C higher than the stretching temperature, and then cool it to the stretching temperature before stretching.

[0170] 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 the thickness becomes uneven. Furthermore, the raw film does not stick to the roll or sag under its own weight.

[0171] 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.

[0172] In addition, when the imide structure-containing acrylic resin in this embodiment is formed into a raw film and then stretched, it is difficult to improve the thickness accuracy by utilizing the necking phenomenon. Therefore, in this embodiment, it is important to control the preheating temperature in order to maintain or improve the thickness accuracy of the obtained film.

[0173] 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 (imide structure-containing acrylic resin composition) determined by DSC is Tg, the temperature is preferably in the range of (Tg - 30°C) to (Tg + 30°C), more preferably (Tg - 20°C) to (Tg + 30°C), even more preferably (Tg) to (Tg + 30°C), and even more preferably (Tg + 10°C) to (Tg + 30°C). In other words, when the glass transition temperature of the imide structure-containing acrylic resin composition is Tg, the stretching temperature for biaxial stretching of the optical film is preferably in the range of Tg - 30°C or more to Tg + 30°C or less.

[0174] If the stretching temperature is within the above temperature range, the 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. Furthermore, problems such as the film sticking to the roll can be prevented.

[0175] 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.

[0176] 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.

[0177] 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.

[0178] If the stretching ratio is within the above range, the mechanical properties of the film, such as elongation, tear propagation strength, and 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.

[0179] When the imide structure-containing acrylic resin in this embodiment contains a crosslinked elastomer, the resulting film has excellent mechanical strength, and therefore any of an unstretched film, a uniaxially stretched film, and a biaxially stretched film can be suitably used.

[0180] (ix) Antenna substrate containing an imide structure-containing acrylic resin composition The antenna substrate containing the imide structure-containing acrylic resin composition of this embodiment can be a film formed from the imide structure-containing acrylic resin composition.

[0181] Because of its excellent dielectric properties, heat resistance, weather resistance, and transparency, the antenna substrate of this embodiment can be used for windowpanes of vehicles, windowpanes of buildings, display units of industrial machinery, displays of electronic devices and display devices in homes, etc.

[0182] 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.

[0183] 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]

[0184] The present invention will be specifically described below using examples, but the present invention is not limited to these examples. The imide structure acrylic resin was evaluated as follows. In the following, "parts" and "%" mean "parts by weight" and "% by weight" unless otherwise specified.

[0185] (glass transition temperature) Using 10 mg of the imide structure-containing acrylic resin, a differential scanning calorimeter (DSC, manufactured by SII Corporation, DSC7020) was used to measure under a nitrogen atmosphere at a temperature rise rate of 20°C / min, and the calorific value was determined by the midpoint method.

[0186] (average refractive index) Measurements were taken using an Abbe refractometer 3T manufactured by Atago Co., Ltd.

[0187] (Calculation of ring structure content) The obtained imide structure-containing acrylic resin 1 Measurement was carried out using H-NMR BRUKER Avance III (400 MHz). The weight ratio was calculated by converting the molar ratio of the target ring structure portion to the other portion. Specifically, 3 In the case of N-phenylglutarimide, where CH is phenyl, the content (mol) of the ring structure was calculated using the following formula from the peak area A at around 0.5 to 2.5 ppm due to the methylene group CH2 and methyl group CH3 of the main chain, the peak area B at around 6.8 to 7.2 ppm due to the protons of the aromatic ring of N-phenylglutarimide, and the peak area C at around 7.3 ppm to 7.6 ppm. The calculated molar ratio can be used to convert to weight and calculate the content. Ring structure content (mol) = (B + C) / A

[0188] (yield) The yield was calculated from the molar ratio of the imidizing agent added to the content of the imide ring structure in the imide structure-containing acrylic resin having the structure represented by formula (1) using the following formula. Yield (mol %) = Ring structure content (mol) / Added imidizing agent (mol) × 100

[0189] (Imidization rate) The imidization rate of the imide structure-containing acrylic resin was determined by measuring the IR spectrum using a Fourier transform infrared spectrophotometer (JASCO FI / IR-4100). -1 The absorption due to the ester carbonyl group in the vicinity and the absorption at 1680cm -1 The imidization ratio was determined from the intensity ratio of the absorption due to the imide carbonyl group near the ester carbonyl group to the absorption due to the imide carbonyl group near the ester carbonyl group, using the following formula: Here, the imidization ratio is the proportion of the imide carbonyl group in the total of the ester carbonyl group and the imide carbonyl group. Imidization rate (%) = absorption intensity of imide carbonyl group / (absorption intensity of ester carbonyl group + absorption intensity of imide carbonyl group)

[0190] (Thickness measurement) The thickness of the optical film was measured using a Digimatic Indicator (manufactured by Mitutoyo Corporation).

[0191] (Optical properties) The in-plane retardation Δnd and the thickness direction retardation Rth were measured using a retardation measuring device KOBRA-WR manufactured by Oji Scientific Instruments Co., Ltd. The measurement was carried out at a wavelength of 590 nm.

[0192] (Total light transmittance and haze value) The total light transmittance and haze value of the resin composition (molded article) or film were measured using an NDH-300A manufactured by Nippon Denshoku Industries Co., Ltd. according to the method described in JIS K7105.

[0193] (Light transmittance at 380 nm) The light transmittance of the optical film at a wavelength of 380 nm was measured using an ultraviolet-visible spectrophotometer (JASCO: V-560).

[0194] (relative permittivity Dk, dielectric loss tangent Df) The dielectric constant Dk and dielectric loss tangent Df were measured using a network analyzer N5224B (Keysight Technologies), a cavity resonator, and the cavity resonator perturbation analysis software CP-MA (Kanto Electronics Application Development Co., Ltd.). The film to be measured was cut into 2 mm x 100 mm pieces and measured after 24 hours of humidity conditioning in a 23°C / 50% RH environment. Measurements were performed at 3 GHz.

[0195] (Coefficient of Linear Expansion (CTE)) The linear expansion coefficient was estimated using a thermomechanical analyzer manufactured by SII Nanotechnology Corporation, product name: TMA / SS6100, by heating from 10°C to 100°C at 10°C / min, then cooling to 10°C at 40°C / min, and further heating at 10°C / min, at the second heating time from 50 to 100°C. The measurement conditions are as follows: Sample shape: width 3mm, length 10mm Load: 1g Atmosphere: Air atmosphere

[0196] (weather resistance) Weather resistance was measured using a xenon weatherometer with an irradiation energy of 63W / m 2 The changes in YI and total light transmittance were measured after 300 hours under conditions of a temperature of 40°C (black panel temperature: 63°C) and rainfall. A change in YI of 1 or more or a change in total light transmittance of 1% or more was marked as x.

[0197] (Yellowness index YI measurement) The tristimulus values ​​X, Y, and Z were measured using a handy color difference meter NR-11B manufactured by Nippon Denshoku Industries Co., Ltd., and the yellowness index YI was calculated from these tristimulus values ​​in accordance with JIS-K7103.

[0198] (Flexibility (MIT flex test)) The film was cut into 15 mm wide strips to serve as test specimens. These test specimens were subjected to measurement using a Toyo Seiki MIT Fatigue Resistance Tester Model D under the following conditions: a test load of 1.96 N, a speed of 175 times / min, a bending clamp curvature radius R of 0.38 mm, and a bending angle of 135° to the left and right. Measurements were performed in both the MD and TD directions, and the arithmetic average was taken as the MIT round-trip bending count.

[0199] Example 1 The resin was produced using a 40mm diameter, fully intermeshing, co-rotating twin-screw extruder reactor. The extruder was a 40mm diameter, co-rotating, intermeshing twin-screw extruder with an L / D (ratio of extruder length L to diameter D) 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.

[0200] An imide structure-containing acrylic resin was produced using polymethyl methacrylate resin (MW: 100,000) as the raw (meth)acrylic polymer, aniline (Fujifilm Wako Pure Chemical Industries, Ltd.) as the imidization agent, and diethylamine (Fujifilm Wako Pure Chemical Industries, Ltd.) as the imidization accelerator. The extruder maximum temperature was 280°C, the screw rotation speed was 100 rpm, the polymethyl methacrylate resin was 10 kg / h, the aniline was added at 8.0 parts per 100 parts of polymethyl methacrylate resin, and the diethylamine was added at 6.3 parts per 100 parts of polymethyl methacrylate resin. The imidization agent and imidization accelerator were mixed in advance, and the aniline and diethylamine mixture was added to the extruder using a liquid addition pump. The imidization rate of the resulting imide structure-containing acrylic resin was 27.2%, the acid value was 0.77 mmol / g, the Tg was 134°C, and the yield was 81%.

[0201] This pellet-shaped imide structure-containing acrylic resin was dried at 100°C for 8 hours, and then extruded at 240°C using a 40mmΦ single-screw extruder and a 400mm wide T-die to obtain a sheet-shaped molten resin. The resulting sheet was cooled with a cooling roll to obtain a film with a width of 300mm and a thickness of 150µm. This film was then uniaxially stretched at a stretch ratio of 2 and a temperature 5°C higher than the Tg to produce a uniaxially stretched film.

[0202] Example 2 、4 ~9 Reference Example 3 , Comparative Examples 1 to 6) Example 2 、4 ~9 Reference Example 3 Comparative Examples 1 to 6 were carried out in the same manner as Example 1, except that the type and the number of parts added of the imidization agent and the type and the number of parts added of the imidization accelerator were changed according to Table 1. The results are shown in Table 1.

[0203] [Table 1]

[0204] As shown in Table 1, when imidization is performed using an aromatic amine compound, the addition of an imidization accelerator having a pKa of 6 or more allows the imidization to proceed efficiently, and an imide structure-containing acrylic resin can be obtained in good yield. In Comparative Examples 2 and 3, the imidization accelerator added was a tertiary amine, so the imidization reaction did not proceed efficiently, and the glass transition temperature of the obtained resin was confirmed to be low. Example 1 、2、4 ~9 Reference Example 3 The glass transition temperature of the imide-structured acrylic resin obtained in Example 1 is higher than those in Comparative Examples 1 to 5, and it is found to be suitable for applications requiring heat resistance. In Comparative Example 6, the imidizing agent added is monomethylamine, and it was confirmed that the thickness direction retardation and in-plane retardation were large.

Claims

1. A method for producing an imide structure-containing acrylic resin having a structure represented by the following formula (1): The method includes a step of heating a raw material composition containing a (meth)acrylic polymer, an imidizing agent, and an imidization accelerator, the imidizing agent contains an aromatic amine compound, the imidization accelerator is a secondary amine, The secondary amine has a structure represented by the following formula (3): the imidization accelerator has a pKa of 6 or more; the raw material composition has an imidizing agent content of 1 to 61.6 parts by weight relative to 100 parts by weight of the (meth)acrylic polymer, and an imidization accelerator content of 6.3 to 80 parts by weight relative to 100 parts by weight of the (meth)acrylic polymer. 【Chemistry 1】 (In formula (1), R １ and R ２ are each independently a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and R ３ is an aromatic hydrocarbon group or a heteroaromatic group. HN(R5)(R6) (3) (In formula (3), R 5 and R 6 each independently represent an alkyl group having 1 to 8 carbon atoms.)

2. 2. The method for producing an imide structure-containing acrylic resin according to claim 1, wherein the raw material composition has an imidizing agent content of 1 to 46.6 parts by weight relative to 100 parts by weight of the (meth)acrylic polymer.

3. 3. The method for producing an imide structure-containing acrylic resin according to claim 1, wherein the imide structure-containing acrylic resin has an imidization rate of 10 to 75%.

4. The method for producing an imide structure-containing acrylic resin according to any one of claims 1 to 3, wherein the imidization accelerator has a pKa of 8 or more.

5. The method for producing an imide structure-containing acrylic resin according to any one of claims 1 to 4, wherein the secondary amine comprises at least one selected from the group consisting of diethylamine, dimethylamine, N-methylethylamine, N-methylpropylamine, and N-methylbutylamine.

6. The method for producing an imide structure-containing acrylic resin according to any one of claims 1 to 5, wherein the imidizing agent comprises at least one selected from the group consisting of aniline, toluidine, anisidine, xylidine, aminopyridine, aminobiphenyl, and aminonaphthalene.

7. 7. The method for producing an imide structure-containing acrylic resin according to claim 1, wherein the raw material composition contains 0.1 mol to 10 mol of the imidization accelerator per 1 mol of the imidizing agent.

8. The method for producing an imide structure-containing acrylic resin according to any one of claims 1 to 7, wherein the (meth)acrylic polymer contains a methacrylic acid alkyl ester unit.

9. The method for producing an imide structure-containing acrylic resin according to claim 8, wherein the methacrylic acid alkyl ester unit has an alkyl group having 1 to 8 carbon atoms.

10. 10. The method for producing an imide structure-containing acrylic resin according to claim 8, wherein the (meth)acrylic polymer has a content of the methacrylic acid alkyl ester unit of 50% by weight or more based on the total amount of the (meth)acrylic polymer.

11. The method for producing the imide structure-containing acrylic resin according to any one of claims 1 to 10, comprising a step of mixing a mixture of the imidization accelerator and the imidizing agent with the (meth)acrylic polymer.

12. The method for producing an imide structure-containing acrylic resin according to any one of claims 1 to 11, wherein a temperature in the step of heating a raw material composition containing the (meth)acrylic polymer, the imidizing agent, and the imidization accelerator is 180°C to 320°C.

13. The method for producing an imide structure-containing acrylic resin according to any one of claims 1 to 12, wherein a pressure in the step of heating a raw material composition containing the (meth)acrylic polymer, the imidizing agent, and the imidization accelerator is 0.1 MPa to 50 MPa.

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