JP5586165B2 - Acrylic protective film - Google Patents

Description

  The present invention relates to a method for producing a protective film obtained by stretching an acrylic resin-containing film.

  In recent years, electronic devices have become increasingly smaller, as represented by notebook personal computers, word processors, mobile phones, personal digital assistants, and the like. In an electronic device having a display device such as the electronic device exemplified above, a liquid crystal display device that takes advantage of light weight and compactness is often used.

  In these liquid crystal display devices, various films such as a polarizing film are used in order to maintain the display quality. Furthermore, in these liquid crystal display devices, in order to further reduce the weight of the liquid crystal display device for portable information terminals and mobile phones, a resin film or sheet (hereinafter, unless otherwise specified) A liquid crystal display device using a film) is also put into practical use.

  In this case, the resin film is required to be optically transparent, have low birefringence, and be optically homogeneous in order to handle polarized light. In other words, in a liquid crystal display device, a resin film used in place of a glass substrate is required to have a small phase difference expressed by the product of birefringence and thickness, and in addition to a film caused by external stress or the like. It is required that the phase difference is difficult to change.

  Conventionally, glass lenses have been used in various photographing devices such as cameras, film-integrated cameras, video cameras, optical pickup devices such as CDs and DVDs, and office automation equipment such as projectors. However, in recent years, lenses used in these devices have been replaced with resin lenses for the purpose of weight reduction.

  Such a resin lens is easily affected by a phase difference due to generation of a shift in focal length due to distortion caused by a use environment such as temperature and humidity, or generation of stress during processing such as injection molding. Therefore, the resin lens is also required to have a phase difference that hardly changes due to an external stress, as in the case of a resin film used in a liquid crystal display device or the like.

  By the way, in a liquid crystal display device, an acrylic resin film is known as a resin film having excellent optical characteristics (Patent Document 1, Patent Document 2, and Patent Document 3).

  Patent Document 1 discloses an acrylic resin film containing an imide resin, Patent Document 2 discloses an acrylic resin film containing a lactone ring, and Patent Document 3 discloses glutaric anhydride.

  However, when an acrylic resin film is used as a film, the mechanical strength is not sufficient, and there is room for improvement in its properties.

  As a method of improving these strengths, a method of stretching an imide resin-containing film to improve tensile elongation and tensile strength is known (Patent Document 4).

  Moreover, the manufacturing method of the phase difference film which improved the flexibility of the lactone ring containing resin film is disclosed (patent document 5).

JP 2006-317560 A JP2008-9378 JP2007-254703 JP-A-6-297558 JP 2008-242426 A

  However, the above-mentioned Patent Document 4 has a problem in that a phase difference is manifested and there is anisotropy in the tensile strength and tensile elongation in the film longitudinal direction and in the width direction. Moreover, since the said patent document 5 aims at the phase difference film and when the method of patent document 5 is implemented, since phase difference will express, there existed a problem when using as a polarizer protective film. This invention is made | formed in view of said problem, The objective is related with the manufacturing method of the film which has high tensile strength and tensile elongation, and also has the performance suitable as a polarizer protective film.

  As a result of intensive studies in view of the above-mentioned problems, the present inventors have produced a film made of an acrylic resin by a specific stretching method, thereby having high tensile strength and tensile elongation and excellent acrylic protection with excellent optical properties. The inventors have uniquely found that a film can be obtained, and have completed the present invention. That is, the present invention relates to the following.

(I) a first-axis stretching step of stretching an unstretched film containing an acrylic resin at a stretching ratio of 150% or more, a stretching speed of 5 times / min or more, and at a temperature of 5 ° C. lower than the glass transition temperature of the film; A stretching ratio of 150% or more, a stretching speed of 10 times / min or less, and a glass transition temperature of the film, a glass transition temperature of the film + a second axis stretching step of stretching at a temperature within 10 ° C,
The stretching temperature of the second axis is not less than the stretching temperature of the first axis and not more than (first axis stretching temperature +10) ° C., and the stretching speed of the first axis is 1.5 times or more and 7 times or less of the stretching speed of the second axis. The manufacturing method of the acrylic protective film characterized by these.

  (Ii) The production method according to (i), wherein the acrylic resin protective film does not contain a rubber component.

  (Iii) The method according to (i) or (ii), wherein the acrylic resin is a lactone resin, a glutaric anhydride resin, or a glutarimide resin.

  (Iv) The glutarimide resin is represented by the following general formula (1)

Wherein R ¹ and R ² are each independently hydrogen or an alkyl group having 1 to 8 carbon atoms, and R ³ is an alkyl group having 1 to 18 carbon atoms or a cycloalkyl having 3 to 12 carbon atoms. Or a substituent containing an aromatic ring having 5 to 15 carbon atoms.)
And the following general formula (2)

Wherein R ⁴ and R ⁵ are each independently hydrogen or an alkyl group having 1 to 8 carbon atoms, and R ⁶ is an alkyl group having 1 to 18 carbon atoms or a cycloalkyl having 3 to 12 carbon atoms. Or a group containing an aromatic ring having 5 to 15 carbon atoms.), And a unit represented by (i) to (iii).
(V) The glutarimide resin is represented by the following general formula (3)

(In the formula, R ⁷ is hydrogen or an alkyl group having 1 to 8 carbon atoms, and R ⁸ is an aryl group having 6 to 10 carbon atoms.)
The production method according to any one of (i) to (iv), further comprising a unit represented by:
(Vi) The front phase difference is 5 nm or less, the breaking elongation in the film longitudinal direction is 10% or more, the breaking elongation in the width direction is 10% or more, the breaking elongation in the film longitudinal direction / breaking elongation in the film width direction. An acrylic protective film having a degree of 2 or less and containing no rubber component.
(Vii) An acrylic protective film produced by biaxial stretching.
(Viii) A polarizer protective film comprising the acrylic protective film according to (vii).
(Ix) A polarizing plate comprising at least one polarizer protective film according to (viii).

  As described above, the acrylic protective film according to the present invention has a breaking elongation in the longitudinal direction of the film of 10% or more and a breaking elongation in the width direction of 10% or more although it does not contain a rubber component. Also, the elongation anisotropy in the longitudinal direction and the width direction is small, and further, the retardation is small, and there is an effect that a film having performance suitable as a polarizer protective film can be produced.

An embodiment of the present invention will be described as follows, but the present invention is not limited to this.
(1) Acrylic resin In the present application, an acrylic resin is a generic term for a polymer obtained by using an acrylic monomer as a main raw material, and a resin obtained by modifying and / or reacting them.

  By forming the acrylic resin according to the present invention into a film, a film having a small phase difference expressed by the product of birefringence and thickness and less likely to change due to external stress or the like is manufactured. Can do. That is, the acrylic resin according to the present invention can be suitably used as an optical film, particularly a polarizer protective film, characterized in that it has a small phase difference in use for optical film production.

  The acrylic resin is not particularly limited, but is preferably a lactone resin, a glutaric anhydride resin, or a glutarimide resin. The lactone resin is not particularly limited, but can be produced according to the method described in JP-A-2008-9378. Although it does not restrict | limit especially as glutaric anhydride resin, It can manufacture according to the method of Unexamined-Japanese-Patent No. 2007-254703, etc.

  The glutarimide resin will be described in detail below. Specific examples of the glutarimide resin include, for example, the following general formula (1):

(Wherein R1 and R2 are each independently hydrogen or an alkyl group having 1 to 8 carbon atoms, and R3 is an alkyl group having 1 to 18 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, or This is a substituent containing an aromatic ring having 5 to 15 carbon atoms.)
(Hereinafter also referred to as “glutarimide unit”),
The following general formula (2)

(Wherein R4 and R5 are each independently hydrogen or an alkyl group having 1 to 8 carbon atoms, and R6 is an alkyl group having 1 to 18 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, or This is a substituent containing an aromatic ring having 5 to 15 carbon atoms.)
A glutarimide resin containing a unit represented by the following (hereinafter also referred to as “(meth) acrylic acid ester unit”) can be suitably used.

  In addition, the glutarimide-based resin may have the following general formula (3) as necessary.

(In the formula, R7 is hydrogen or an alkyl group having 1 to 8 carbon atoms, and R8 is an aryl group having 6 to 10 carbon atoms.)
(Hereinafter also referred to as “aromatic vinyl unit”).

  In the general formula (1), R1 and R2 are each independently hydrogen or a methyl group, R3 is preferably hydrogen, a methyl group, a butyl group, or a cyclohexyl group, and R1 is a methyl group R2 is more preferably hydrogen and R3 is more preferably a methyl group.

  The glutarimide resin may include only a single type as a glutarimide unit, or may include a plurality of types in which R1, R2, and R3 in the general formula (1) are different.

  The glutarimide unit can be formed by imidizing the (meth) acrylic acid ester unit represented by the general formula (2).

  In addition, acid anhydrides such as maleic anhydride, or half esters of such acid anhydrides and linear or branched alcohols having 1 to 20 carbon atoms; acrylic acid, methacrylic acid, maleic acid, maleic anhydride, The glutarimide unit can also be formed by imidizing an α, β-ethylenically unsaturated carboxylic acid such as itaconic acid, itaconic anhydride, crotonic acid, fumaric acid or citraconic acid.

  In the general formula (2), R4 and R5 are each independently hydrogen or a methyl group, R6 is preferably hydrogen or a methyl group, R4 is hydrogen, R5 is a methyl group, R6 is more preferably a methyl group.

  The glutarimide-based resin may include only a single type as a (meth) acrylic acid ester unit, or may include a plurality of types in which R4, R5, and R6 in the general formula (2) are different. May be.

  The glutarimide resin may contain styrene, α-methylstyrene or the like as the aromatic vinyl constituent unit represented by the general formula (3).

  Moreover, the said glutarimide-type resin may contain only the single kind as an aromatic vinyl structural unit, and may contain the several kind from which R7 and R8 differ.

  When the glutarimide-based resin contains an acrylate unit, the content is preferably less than 1% by weight, and more preferably less than 0.5% by weight.

  If the acrylate unit is within the above range, the imide resin will have excellent thermal stability, but if it exceeds the above range, the thermal stability will deteriorate, and the resin molecular weight and viscosity during resin production or molding will be reduced. Tends to deteriorate and the physical properties tend to deteriorate.

  In the glutarimide-based resin, the content of the glutarimide unit represented by the general formula (1) is not particularly limited. For example, the content of the general formula (3) or the general formula (1) R3 It is preferable to change depending on the structure and the like.

  In general, the content of the glutarimide unit is preferably 2% by weight or more of the glutarimide resin, more preferably 2% to 95% by weight, and 2% to 90% by weight. More preferably, it is more preferably 2 to 80% by weight.

  If the content of the glutarimide unit is within the above range, the heat resistance and transparency of the resulting glutarimide resin may decrease, or the moldability and mechanical strength when processed into a film may decrease. There is no.

  On the other hand, when the content of the glutarimide unit is less than the above range, the resulting glutarimide resin tends to be insufficient in heat resistance or impaired in transparency. On the other hand, if the amount is larger than the above range, the heat resistance and melt viscosity are unnecessarily increased, the molding processability is deteriorated, the mechanical strength during film processing becomes extremely brittle, or the transparency is impaired. Tend.

  In the glutarimide resin, the content of the aromatic vinyl unit represented by the general formula (3) is not particularly limited, and can be appropriately set according to required physical properties. Depending on the application used, the content of the aromatic vinyl unit represented by the general formula (3) may be zero.

  The glutarimide resin may be further copolymerized with other units other than the glutarimide unit, the (meth) acrylic acid ester unit, and the aromatic vinyl unit, if necessary.

  As other units, for example, nitrile monomers such as acrylonitrile and methacrylonitrile, and maleimide monomers such as maleimide, N-methylmaleimide, N-phenylmaleimide, and N-cyclohexylmaleimide are copolymerized. A structural unit can be mentioned.

  These other units may be directly copolymerized or graft copolymerized in the glutarimide resin.

The weight average molecular weight of the glutarimide resin is not particularly limited, but is preferably 1 × 10 ^{4 to} 5 × 10 ⁵ , and more preferably 5 × 10 ^{4 to} 3 × 10 ⁵ . If it is in the said range, moldability will not fall or the mechanical strength at the time of film processing will not be insufficient.

  On the other hand, when the weight average molecular weight is smaller than the above range, the mechanical strength when formed into a film tends to be insufficient. Moreover, when larger than the said range, the viscosity at the time of melt-extrusion is high, there exists a tendency for the moldability to fall and for the productivity of a molded article to fall.

  The glass transition temperature of the glutarimide resin is not particularly limited, but is preferably 110 ° C. or higher, more preferably 115 ° C. or higher. If the glass transition temperature is within the above range, the application range of the resulting acrylic resin can be expanded.

  On the other hand, for example, if the glass transition temperature is lower than the above range, the application range is limited in applications where heat resistance is required.

  The acid value of the glutarimide resin is not particularly limited, but is preferably 1.0 mmol / g or less, and more preferably 0.5 mmol / g or less. If an acid value is in the said range, the application range of the acrylic resin obtained can be expanded.

  On the other hand, for example, when the acid value is larger than the above range, foaming of the resin at the time of melt extrusion tends to occur, the moldability tends to be lowered, and the productivity of the molded product tends to be lowered.

  Here, the acid value represents the content of carboxylic acid units and carboxylic anhydride units in the resin. The acid value can be calculated by, for example, a titration method described in JP-A-2005-23272.

  In the glutarimide resin, the content (in other words, the ratio) of the units represented by the general formulas (1) to (3) is not particularly limited, and physical properties required for the glutarimide resin. Alternatively, it may be determined according to characteristics required for a film formed by molding the acrylic resin according to the present invention.

  Here, although one Embodiment of the manufacturing method of the said glutarimide type resin is described, this invention is not limited to this.

  First, a (meth) acrylic acid ester polymer is produced by polymerizing a (meth) acrylic acid ester. The production method is not particularly limited, and known emulsion polymerization methods, emulsion-suspension polymerization methods, suspension polymerization methods, bulk polymerization methods, solution polymerization methods, and the like can be applied. From the viewpoint of being small, the bulk polymerization method and the solution polymerization method are particularly preferable. For example, it can be produced according to the methods described in JP-A-56-8404, JP-B-6-86492, JP-B-52-32665, and the like. The (meth) acrylic acid ester polymer is preferably polymethyl methacrylate.

  When the glutarimide resin of the present invention contains an aromatic vinyl unit, a (meth) acrylic acid ester and an aromatic vinyl are copolymerized to produce a (meth) acrylic acid ester-aromatic vinyl copolymer. . The methyl methacrylate-styrene copolymer is produced according to the method described in, for example, JP-A-57-149111, JP-A-57-153010, JP-A-10-152505, JP-A-2001-31046, JP-A-2004-27191, etc. it can.

  When the glutarimide resin of the present invention contains an acrylate unit, the acrylate unit in the (meth) acrylate polymer used as a raw material is preferably less than 1% by weight, and 0.5% by weight. More preferably, it is less than%.

  In this step, examples of the (meth) acrylic acid ester include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, and (meth) acrylic acid t. -Butyl, benzyl (meth) acrylate, and cyclohexyl (meth) acrylate are preferably used, and methyl methacrylate is more preferably used.

  These (meth) acrylic acid esters may be used alone or in combination of two or more. By using multiple types of (meth) acrylic acid esters, it is possible to give multiple types of (meth) acrylic acid ester units to the finally obtained glutarimide resin.

  Moreover, when the said glutarimide resin contains an aromatic vinyl unit, the ratio of an aromatic vinyl unit can be adjusted by adjusting the polymerization rate of (meth) acrylic acid ester and aromatic vinyl.

  The structures of the (meth) acrylic acid ester-aromatic vinyl copolymer and the (meth) acrylic acid ester polymer are not particularly limited as long as the imidization reaction is possible. Specifically, any of a linear (linear) polymer, a block polymer, a core-shell polymer, a branched polymer, a ladder polymer, and a crosslinked polymer may be used.

  In the case of a block polymer, it may be any of AB type, ABC type, ABA type, and other types of block polymers. In the case of the core-shell polymer, it may be composed of only one core and only one shell, or each may be composed of multiple layers.

  Next, an imidizing agent is added to the (meth) acrylic acid ester polymer or (meth) acrylic acid ester-aromatic vinyl copolymer to perform imidization. Thereby, the said glutarimide type-resin can be manufactured.

  The imidizing agent is not particularly limited as long as it can generate the glutarimide unit represented by the general formula (1), and examples thereof include those described in WO2005 / 054311. Specifically, for example, an aliphatic hydrocarbon group-containing amine such as ammonia, methylamine, ethylamine, n-propylamine, i-propylamine, n-butylamine, i-butylamine, tert-butylamine, n-hexylamine, Mention may be made of aromatic hydrocarbon group-containing amines such as aniline, benzylamine, toluidine and trichloroaniline, and alicyclic hydrocarbon group-containing amines such as cyclohexylamine.

  In addition, urea-based compounds that generate amines exemplified above by heating, such as urea, 1,3-dimethylurea, 1,3-diethylurea, and 1,3-dipropylurea, can also be used.

  Of the imidizing agents exemplified above, methylamine, ammonia, and cyclohexylamine are preferably used from the viewpoint of cost and physical properties, and methylamine is particularly preferably used.

  Further, gaseous methylamine or the like at normal temperature may be used in a state dissolved in alcohols such as methanol.

  In this imidization step, a ring closure accelerator (catalyst) may be added as necessary in addition to the imidizing agent.

  In this imidization step, by adjusting the addition ratio of the imidizing agent, the ratio of glutarimide units and (meth) acrylic acid ester units in the resulting glutarimide resin can be adjusted.

  Further, by adjusting the degree of imidization, the physical properties of the resulting glutarimide resin, the optical characteristics of an optical film formed by molding the acrylic resin according to the present invention, and the like can be adjusted.

  A known technique can be used as a method for imidizing the (meth) acrylic acid ester-aromatic vinyl copolymer or the (meth) acrylic acid ester polymer.

  (1) Using an extruder or the like, the (meth) acrylic acid ester polymer or (meth) acrylic acid ester-aromatic vinyl copolymer in a molten state is reacted with an imidizing agent, or (2) imide It can be obtained by reacting (meth) acrylic acid ester polymer or (meth) acrylic acid ester-aromatic vinyl copolymer with an imidizing agent using a non-reactive solvent for the reaction. It is done.

  When producing a glutarimide-type resin using an extruder, the extruder to be used is not specifically limited, 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.

  Among these, it is preferable to use a twin screw extruder. According to the twin screw extruder, when using an imidizing agent (ring closure accelerator) for the raw material polymer (that is, (meth) acrylic acid ester-aromatic vinyl copolymer or (meth) acrylic acid ester polymer), Mixing of an imidizing agent and a ring closure accelerator) can be promoted.

  Examples of the twin-screw extruder include a non-meshing type same direction rotating type, a meshing type same direction rotating type, a non-meshing type different direction rotating type, and a meshing type different direction rotating type. Among them, it is preferable to use a meshing type co-rotating type. Since the meshing type co-rotating twin-screw extruder can rotate at a high speed, mixing of the imidizing agent (in the case of using a ring closure accelerator and an imidization agent and a ring closure accelerator) with the raw polymer is further improved. Can be promoted.

  When imidization is performed in an extruder, for example, a raw material (meth) acrylic acid ester polymer or (meth) acrylic acid ester-aromatic vinyl copolymer is charged from a raw material charging portion of the extruder, After the resin is melted and the inside of the cylinder is filled, an imidizing agent is injected into the extruder using an addition pump, whereby the imidization reaction can proceed in the extruder.

  In this case, the reaction zone temperature (resin temperature) in the extruder is preferably 180 ° C. to 270 ° C., more preferably 200 to 250 ° C. When the temperature of the reaction zone (resin temperature) is less than 180 ° C., the imidization reaction hardly proceeds and the heat resistance tends to decrease. When the reaction zone temperature exceeds 270 ° C., the resin is significantly decomposed, so that the bending resistance of the film that can be formed from the resulting glutarimide-based resin tends to decrease. Here, the reaction zone in the extruder refers to a region between the injection position of the imidizing agent and the resin discharge port (die part) in the cylinder of the extruder.

  By increasing the reaction time in the reaction zone of the extruder, imidization can be further advanced. The reaction time in the reaction zone of the extruder is preferably longer than 10 seconds, and more preferably longer than 30 seconds. In the reaction time of 10 seconds or less, imidation may hardly proceed.

  The resin pressure in the extruder is preferably in the range of atmospheric pressure to 50 MPa, and more preferably in the range of 1 MPa to 30 MPa. If it is less than 1 MPa, the solubility of the imidizing agent is low, and the progress of the reaction tends to be suppressed. On the other hand, if it is 50 MPa or more, the mechanical pressure limit of a normal extruder is exceeded, and a special apparatus is required, which is not preferable in terms of cost.

  The above-exemplified extruders may be used alone, or a plurality of the extruders may be connected in series. For example, a tandem reaction extruder described in JP-A-2008-273140 can be used.

  The extruder is preferably equipped with a vent port that can be reduced to atmospheric pressure or lower. According to such a configuration, unreacted imidizing agent, or by-products such as methanol and monomers can be removed.

  In addition, for the production of the glutarimide-based resin, instead of an extruder, for example, a horizontal biaxial reactor such as Vivolac manufactured by Sumitomo Heavy Industries, Ltd. or a vertical biaxial agitation tank such as Super Blend is used. A high-viscosity reactor can also be suitably used.

  When manufacturing the said glutarimide type-resin using a batch type reaction tank (pressure vessel), the structure of the batch type reaction vessel (pressure vessel) is not specifically limited.

  Specifically, it has a structure in which the raw material polymer can be melted by heating and stirred, and an imidizing agent (in the case of using a ring closure accelerator, an imidizing agent and a ring closure accelerator) can be added. However, it is preferable to have a structure with good stirring efficiency.

  According to such a batch-type reaction vessel (pressure vessel), it is possible to prevent the polymer viscosity from increasing due to the progress of the reaction and the stirring to be insufficient. As a batch type reaction tank (pressure vessel) having such a structure, for example, a stirred tank Max Blend manufactured by Sumitomo Heavy Industries, Ltd. can be exemplified.

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

  According to the method as described above, a glutarimide resin in which the ratio of glutarimide units, (meth) acrylic acid ester units, and aromatic vinyl units is controlled as desired can be easily produced.

  In addition, this invention is characterized by not containing the bridge | crosslinking particle | grains (rubber component) which have flexibility in acrylic resin. By containing a rubber component, the effect of improving the tensile strength and elongation of the obtained film can be obtained, but the transparency required for the optical film may be deteriorated, or foreign matter contained in the film may increase. Yes, not preferred.

  The acrylic resin used in the present invention may contain an additive. Additives include antioxidants, UV absorbers, plasticizers, lubricants, heat stabilizers, light stabilizers, antistatic agents, radical scavengers, colorants, shrinkage inhibitors, antibacterial / deodorants, fillers, etc. A conventionally well-known additive can be mentioned. In addition, thermoplastic resins other than the acrylic resins described above can also be contained as other additives. The other additives are optional components, and the acrylic resin according to the present invention may not contain these other additives.

  The plasticizer is not particularly limited, and any conventionally known plasticizer can be used. Specific examples include aliphatic dibasic acid plasticizers such as di-n-decyl adipate and phosphate ester plasticizers such as tributyl phosphate.

  By including the plasticizer in the acrylic resin according to the present invention, the mechanical properties of the film formed by molding the acrylic resin can be improved.

  On the other hand, the addition of the plasticizer may cause a problem that the glass transition temperature of the resulting film is lowered and the heat resistance is impaired or the transparency is impaired.

  Therefore, when the acrylic resin according to the present invention contains the plasticizer, it is preferably added within a range in which the performance of the film is not hindered in the film formed by molding the acrylic resin.

  Specifically, the content of the plasticizer is preferably 20% by weight or less, preferably 10% by weight or less, and more preferably 5% by weight or less in the acrylic resin.

  When a resin other than the acrylic resin described above is used as the other additive, the resin is not particularly limited. For example, an acrylic resin other than the acrylic resin described above may be used, or a thermosetting resin may be used. Especially, it is preferable to contain acrylic resins other than the acrylic resin described above.

  In addition, resin contained as another additive may be used individually by 1 type, and may be used in combination of multiple types of resin.

  When the above resin is added as another additive, the content in the acrylic resin is preferably 1% by weight to 30% by weight, more preferably 2% by weight to 20% by weight, and more preferably 3% by weight. More preferably, the content is from 10% to 10% by weight.

  On the other hand, when there is more content of the said resin than the said range, there exists a tendency for the performance of the acrylic resin mentioned above and a ultraviolet absorber not to fully exhibit. On the other hand, if the content of the resin is less than the above range, the effect of adding the resin may be difficult to obtain.

  The filler is not particularly limited, and any conventionally known filler used for a film can be used. The filler may be inorganic fine particles or organic fine particles.

  Examples of fillers that are inorganic fine particles include metal oxide fine particles such as silicon dioxide, titanium dioxide, aluminum oxide, and zirconium oxide, and calcined calcium silicate, hydrated calcium silicate, aluminum silicate, and magnesium silicate. Examples include acid salt fine particles, calcium carbonate, talc, clay, calcined kaolin, and calcium phosphate.

  Examples of the filler that is an organic fine particle include resin fine particles such as a silicon resin, a fluorine resin, an acrylic resin, and a crosslinked styrene resin.

  By adding such a filler, the slipperiness of the film can be improved.

  The addition amount of the filler is not particularly limited. However, when the acrylic resin according to the present invention is molded into an optical film, it is preferable that the optical properties of the obtained film are not significantly impaired.

Generally, in the acrylic resin according to the present invention, the filler content is preferably 10% by weight or less.
(2) Film containing acrylic resin (referred to as “raw film” or “unstretched film”)
Here, although one Embodiment of the method to manufacture the film containing the acrylic resin concerning this invention is described, this invention is not limited to this. That is, any conventionally known method can be used as long as it is a method capable of producing a film by molding the acrylic resin according to the present invention.

  Specific examples include injection molding, melt extrusion film molding, inflation molding, blow molding, compression molding, and spinning molding.

  Further, the film according to the present invention can be produced by a solution casting method or a spin coating method in which the acrylic resin according to the present invention is dissolved in a soluble solvent and then molded.

  Among them, it is preferable to use a melt extrusion method that does not use a solvent. According to the melt extrusion method, it is possible to reduce the burden on the global environment and the working environment due to manufacturing costs and solvents.

  Hereinafter, as an embodiment of a method for producing a film according to the present invention, a method for producing a film by molding the acrylic resin according to the present invention by a melt extrusion method will be described in detail. In the following description, a film formed by the melt extrusion method is distinguished from a film formed by another method such as a solution casting method and is referred to as a “melt extrusion film”.

  When the acrylic resin according to the present invention is formed into a film by a melt extrusion method, first, the acrylic resin according to the present invention is supplied to an extruder, and the acrylic resin is heated and melted.

  The acrylic resin is preferably pre-dried before being supplied to the extruder. By performing such preliminary drying, foaming of the resin extruded from the extruder can be prevented.

  The method of preliminary drying is not particularly limited, and for example, the raw material (that is, the acrylic resin according to the present invention) is formed into pellets or the like and can be performed using a hot air dryer or the like.

  Next, the acrylic resin heated and melted in the extruder is supplied to the T die through a gear pump and a filter. At this time, if a gear pump is used, the uniformity of the extrusion amount of the resin can be improved and thickness unevenness can be reduced. On the other hand, if a filter is used, the foreign material in acrylic resin can be removed and the film excellent in the external appearance without a defect can be obtained.

  Next, the acrylic resin supplied to the T die is extruded from the T die as a sheet-like molten resin. Then, the sheet-like molten resin is sandwiched between two cooling rolls and cooled to form a film.

One of the two cooling rolls sandwiching the sheet-like molten resin is a rigid metal roll having a smooth surface, and the other has a metal elastic outer cylinder having a smooth surface and capable of elastic deformation. A flexible roll is preferred.

  With such a rigid metal roll and a flexible roll having a metal elastic outer cylinder, the sheet-like molten resin is sandwiched and cooled to form a film, thereby correcting minute surface irregularities and die lines. Thus, a film having a smooth surface and thickness unevenness of 5 μm or less can be obtained.

In this specification, “cooling roll” is used to mean “touch roll” and “cooling roll”.
(3) Method for Producing Acrylic Protective Film The present invention can produce an acrylic protective film by biaxially stretching a raw material film under specific conditions. Conventionally, in stretched films, it has been difficult to avoid the occurrence of retardation. However, according to the acrylic resin according to the present invention, even when subjected to stretching treatment, the retardation is not substantially generated, and the mechanical difference is not caused. A stretched film with improved properties can be produced.

  The present invention provides a first-axis stretching step in which an unstretched film containing an acrylic resin is stretched at a stretching ratio of 150% or more, a stretching speed of 5 times / min or more, and a temperature that is 5 ° C. lower than the glass transition temperature of the film. A stretching ratio of 150% or more, a stretching speed of 10 times / min or less, and a second-axis stretching step of stretching at a temperature not lower than the glass transition temperature of the film and not higher than the glass transition temperature of the film + 10 ° C.

  The draw ratio of the first axis is preferably 150% or more, and more preferably 170% or more. When the draw ratio of the first axis is less than 150%, the breaking elongation of the obtained film is insufficient, and the film strength tends to be insufficient.

  The stretching speed of the first axis is preferably 5 times / minute or more, and more preferably 8 times / minute or more. When the stretching speed of the first axis is less than 5 times / minute, the breaking elongation of the obtained film is insufficient, and the film strength tends to be insufficient.

  The stretching temperature of the first axis is preferably (the glass transition temperature of the raw material film −5 ° C.) or higher, and more preferably (the glass transition temperature of the raw material film −2 ° C.) or higher. If the first-axis stretching temperature is less than (the glass transition temperature of the raw material film −5 ° C.), the film may be broken during stretching, such being undesirable.

  The stretching ratio of the second axis is preferably 150% or more, and more preferably 170% or more. When the draw ratio of the first axis is less than 150%, the elongation at break of the obtained film becomes insufficient and the film strength tends to be insufficient.

  The stretching speed of the second axis is preferably 10 times / minute or less, and more preferably 8 times / minute or less. When the stretching speed of the second axis is larger than 10 times / minute, the phase difference of the obtained film is increased, and the film optical characteristics tend to be deteriorated.

  The stretching temperature of the second axis is preferably equal to or higher than the glass transition temperature of the raw material film, and more preferably equal to or higher than (glass transition temperature of the raw material film −2 ° C.). When the stretching temperature of the second axis is equal to or lower than the glass transition temperature of the raw material film, the phase difference of the obtained film increases, and the film optical properties tend to deteriorate.

  The stretching temperature of the second axis is preferably not less than the stretching temperature of the first axis and not more than (first-axis stretching temperature + 10) ° C., more preferably not less than the stretching temperature of the first axis and not more than (first-axis stretching temperature + 8) ° C. . That is, (biaxial stretching temperature−first axial stretching temperature) ° C. is preferably 0 ° C. or higher and 10 ° C. or lower, and more preferably 0 ° C. or higher and 8 ° C. or lower. If the stretching temperature of the second axis is lower than the stretching temperature of the first axis, the elongation at break of the obtained film may be insufficient, or the film may be broken at the time of stretching. Tends to be insufficient and the film strength tends to be insufficient.

  Further, the stretching speed of the first axis is preferably 1.5 times or more and 7 times or less, and more preferably 1.7 times or more and 6 times or less with respect to the stretching speed of the second axis. When the stretching speed of the first axis is less than 1.5 times the stretching speed of the second axis, the breaking elongation in the transverse direction of the obtained film becomes insufficient, and the film strength tends to be insufficient, and is larger than 7 times. And the breaking elongation in the transverse direction of the obtained film becomes insufficient, and the film strength may be insufficient. Further, if it is out of the above range, the balance of the breaking elongation in the transverse direction and the longitudinal direction of the film may be poor, and when producing such a biaxially stretched film, the breaking elongation is good in the film direction. It is not preferable because tearing easily occurs.

  By performing biaxial stretching under the conditions described above, the elongation at break in the longitudinal direction of the film is 10% or more and the elongation at break in the width direction is 10% or more without adding a rubber component (breaking elongation in the longitudinal direction). An optical acrylic biaxially stretched film having a degree of elongation in the direction of width / width) of 2 or less and a front phase difference of 10 nm or less can be obtained.

The method for stretching the raw material film is not particularly limited, and any conventionally known stretching method may be used. Specifically, for example, sequential biaxial stretching in which these are sequentially combined, such as longitudinal stretching using a roll and transverse stretching using a tenter, can be used.
(4) Acrylic protective film The acrylic protective film concerning this invention can be manufactured by the said biaxial stretching method. The thickness of the stretched film to be obtained is not particularly limited, but is preferably 10 μm to 200 μm, more preferably 20 μm to 150 μm, and further preferably 30 μm to 100 μm.

  When the thickness of the film is within the above range, an optical film having uniform optical characteristics and good haze can be obtained.

  On the other hand, if the thickness of the film exceeds the above range, the cooling of the film becomes non-uniform and the optical characteristics tend to be non-uniform. Moreover, when the thickness of the film is less than the above range, the draw ratio becomes excessive, and the haze tends to deteriorate.

  The stretched film according to the present invention preferably has a haze of 1% or less, more preferably 0.7% or less, and even more preferably 0.5% or less.

  If the haze of the stretched film according to the present invention is within the above range, the transparency of the film can be increased. Therefore, the stretched film according to the present invention can be suitably used for applications requiring transparency.

  The stretched film according to the present invention preferably has a total light transmittance of 85% or more, more preferably 88% or more.

  If the total light transmittance is within the above range, the transparency of the film can be increased. Therefore, the stretched film according to the present invention can be suitably used for applications requiring transparency.

  Moreover, it is preferable that the stretched film concerning this invention has small optical anisotropy. In particular, it is preferable that not only the optical anisotropy in the in-plane direction (length direction, width direction) of the film but also the optical anisotropy in the thickness direction is small. In other words, it is preferable that both the in-plane retardation and the thickness direction retardation are small.

  More specifically, the in-plane retardation of the raw material film is preferably 10 nm or less, more preferably 5 nm or less, and even more preferably less than 3 nm. The in-plane retardation of the stretched film is preferably 10 nm or less, more preferably 6 nm or less, and further preferably 5 nm or less.

  The thickness direction retardation is preferably 50 nm or less, more preferably 10 nm or less, and further preferably 5 nm or less with respect to the raw material film. Moreover, regarding the stretched film, the thickness direction retardation is preferably 50 nm or less, more preferably 20 nm or less, and further preferably 10 nm or less.

  If it is set as the structure which has such an optical characteristic, the stretched film concerning this invention can be used as a polarizer protective film with which the polarizing plate of a liquid crystal display device is equipped.

  On the other hand, when the in-plane retardation of the film exceeds 10 nm or the thickness direction retardation exceeds 50 nm, when the polarizer protective film using the stretched film according to the present invention is used as a polarizing plate of a liquid crystal display device, There are cases where a problem such as a decrease in contrast occurs in the liquid crystal display device.

  The in-plane retardation (Re) and the thickness direction retardation (Rth) can be calculated by the following equations, respectively. That is, in an ideal film that is completely optically isotropic in the three-dimensional direction, both the in-plane retardation Re and the thickness direction retardation Rth are zero.

Re = (nx−ny) × d
Rth = | (nx + ny) / 2−nz | × d
In the above formula, nx, ny, and nz are respectively the direction in which the in-plane refractive index is the maximum as the X axis, the direction perpendicular to the X axis as the Y axis, and the thickness direction of the film as the Z axis. Represents the refractive index in each axial direction. D represents the thickness of the film, and || represents an absolute value.

The stretched film according to the present invention preferably has a value of orientation birefringence of 0 to 0.1 × 10 ⁻³ , and more preferably 0 to 0.01 × 10 ⁻³ .

  If the orientation birefringence is within the above range, stable optical characteristics can be obtained without causing birefringence during molding even when the environment changes.

  In the present specification, unless otherwise specified, “orientation birefringence” is intended to mean birefringence that develops when stretched 100% at a temperature 5 ° C. higher than the glass transition temperature of the acrylic resin. The orientation birefringence (Δn) is defined by Δn = nx−ny = Re / d and can be measured by a phase difference meter, using nx and ny described above.

In the stretched film according to the present invention, the absolute value of the photoelastic coefficient is preferably 20 × 10 ⁻¹² m ² / N or less, more preferably 10 × 10 ⁻¹² m ² / N or less. × and more preferably at most 10 ^-12 m ² / N.

  If the photoelastic coefficient is within the above range, even if the stretched film according to the present invention is used in a liquid crystal display device, retardation unevenness occurs, the contrast around the display screen decreases, or light leakage occurs. There is nothing to do.

On the other hand, when the absolute value of the photoelastic coefficient is larger than 20 × 10 ⁻¹² m ² / N, when the optical film according to the present invention is used for a liquid crystal display device, unevenness in phase difference occurs or the peripheral portion of the display screen There is a tendency that the contrast of the light is reduced or light leakage is likely to occur. This tendency becomes particularly remarkable in a high temperature and high humidity environment.

  In addition, when an external force is applied to an isotropic solid to generate stress (ΔF), it temporarily exhibits optical anisotropy and exhibits birefringence (Δn). By “photoelastic coefficient” is intended the ratio of stress to birefringence. That is, the photoelastic coefficient (c) is calculated by the following equation.

c = △ n / △ F
However, in the present invention, the photoelastic coefficient is a value measured at 23 ° C. and 50% RH at a wavelength of 515 nm by the Senarmon method.

  The film according to the present invention can be used by laminating another film with an adhesive or the like, or by forming a coating layer such as a hard coat layer on the surface, if necessary.

  The stretched film according to the present invention may be subjected to surface treatment as necessary. Specifically, for example, when the optical film according to the present invention is used by subjecting the surface to surface processing such as coating or laminating another film on the surface, the surface of the stretched film according to the present invention is used. It is preferable to perform the treatment. The surface treatment is not particularly limited, and examples thereof include corona treatment, plasma treatment, ultraviolet irradiation, and alkali treatment. Among these, corona treatment is preferable.

  In the film according to the present invention, when the surface treatment is performed, the degree of the surface treatment is not particularly limited, but is preferably 50 dyn / cm or more, and is 50 dyn / cm to 80 dyn / cm or less. It is more preferable.

  With such a surface treatment, the surface treatment can be performed using a conventionally known surface treatment facility.

  By performing such a surface treatment, mutual adhesion between the stretched film according to the present invention and another film to be coated or laminated can be improved.

  In addition, the objective of the surface treatment with respect to the stretched film concerning this invention is not limited to what aims at an effect. That is, the stretched film according to the present invention may be subjected to a surface treatment regardless of its use.

  As described above, the stretched film according to the present invention is excellent in optical properties such as optical homogeneity and transparency. Therefore, it can use especially suitably for well-known optical uses, such as a liquid crystal display periphery, such as an optically isotropic film, a polarizer protective film, and a transparent conductive film, using these optical characteristics.

  The stretched film of the present invention can be attached to a polarizer and used as a polarizing plate. The polarizer is not particularly limited, and any conventionally known polarizer can be used. Specific examples include a polarizer obtained by containing iodine in stretched polyvinyl alcohol.

  The present invention is not limited to the configurations described above, and various modifications can be made within the scope of the claims, and the technical means disclosed in different embodiments are appropriately combined. The obtained embodiment is also included in the technical scope of the present invention.

  The present invention will be described more specifically based on examples and comparative examples, but the present invention is not limited to this. Those skilled in the art can make various changes, modifications, and alterations without departing from the scope of the present invention. In the following Examples and Comparative Examples, TGA measurement, calculation of imidization rate, calculation of styrene amount, determination of glass transition temperature, measurement of film thickness, and in-plane retardation measurement were performed according to the following procedures.

(Calculation of imidization rate)
The product pellets were dissolved in methylene chloride, and the IR spectrum of the solution was measured at room temperature using Travel IR manufactured by SensIR Technologies.

From the obtained IR spectrum, and absorption intensity (Abs _Ester) attributed to the ester carbonyl group of 1720 cm ^-1, the absorption intensity assignable to an imide carbonyl group of 1660cm ^-1 (Abs _imide) and imidization ratio from the ratio of (Im% (IR)) was determined.

  Here, the “imidization rate” refers to the ratio of the imide carbonyl group in the total carbonyl group.

[Calculation of styrene content]
The raw material resin (about 10 mg) was dissolved in deuterated chloroform (about 4 mL), and a ¹ H-NMR spectrum of the solution was measured using a Varian NMR measuring apparatus Gemini-300.

From the obtained ¹ H-NMR spectrum, it is attributed to the aromatic-derived proton of the styrene unit at δ = 7.4 to 6.8 and the ester of the methyl methacrylate unit at δ = 3.8 to 2.2. The amount of styrene was determined from the integral intensity ratio of protons.

(Acid value measurement)
0.3 g of the resin was dissolved in 37.5 mL of methylene chloride, and 37.5 mL of methanol was further added. Next, 5 mL of 0.1 mmol% sodium hydroxide aqueous solution and several drops of ethanol solution of phenolphthalein were added. Next, back titration was performed using 0.1 mmol% hydrochloric acid, and the acid value was determined from the amount of hydrochloric acid required for neutralization.

[Elongation at break and strength at break]
Measurements were made using the Autograph AG-2000A model manufactured by Shimadzu Corporation, applying the method described in JIS K7162. Measurement was performed at n = 3, and the average value of strength (MPa) and elongation (%) when the test piece was broken was adopted. A test piece having a shape of No. 1 and a thickness of about 40 μm was used. The test was conducted at 23 ° C. with a test speed of 50 mm / sec.

〔Glass-transition temperature〕
Using an unstretched film of 10 mg, a differential scanning calorimeter (DSC, model DSC-50 manufactured by Shimadzu Corporation) was used and measured at a heating rate of 20 ° C./min under a nitrogen atmosphere, and determined by a midpoint method. .

(Thickness measurement)
The thickness of the test piece measured using a digimatic indicator (manufactured by Mitutoyo Corporation) was measured.

(In-plane phase difference measurement)
A 40 mm × 40 mm test piece was cut out from the film. Using an automatic birefringence meter (KOBRA-WR manufactured by Oji Scientific Co., Ltd.), the in-plane retardation Re was measured at a temperature of 23 ± 2 ° C. and a humidity of 50 ± 5% at a wavelength of 590 nm and an incident angle of 0 °. It was measured.

[Production Example 1]
An imidized resin was produced using a methyl methacrylate-styrene copolymer having a molecular weight of 100,000 (styrene content: 11 mol%) as a raw material resin and monomethylamine as an imidizing agent.

  The extruder used was a meshing type co-rotating twin screw extruder having a diameter of 15 mm. The set temperature of each temperature control zone of the extruder was 230 to 250 ° C., and the screw rotation speed was 150 rpm. A methyl methacrylate-styrene copolymer (hereinafter also referred to as “MS resin”) was supplied at 2 kg / hr, and the resin was melted and filled with a kneading block, and then 16 parts by weight of monomethyl from the nozzle to the resin. Amine (Mitsubishi Gas Chemical Co., Ltd.) was injected. A reverse flight was placed at the end of the reaction zone to fill the resin. By-products and excess methylamine after the reaction were removed by reducing the pressure at the vent port to -0.092 MPa. The resin that emerged as a strand from the die provided at the exit of the extruder was cooled in a water tank and then pelletized with a pelletizer to obtain an imidized MS resin (1).

  Next, in a meshing type co-rotating twin screw extruder with a diameter of 15 mm, the set temperature of each temperature control zone of the extruder was 230 ° C. and the screw rotation speed was 150 rpm. The imidized MS resin (1) obtained from the hopper was supplied at 1 kg / hr, and the resin was melted and filled with a kneading block, and then 0.8 parts by weight of dimethyl carbonate and 0. A mixed solution of 2 parts by weight of triethylamine was injected to reduce carboxyl groups in the resin. A reverse flight was placed at the end of the reaction zone to fill the resin. The by-product after reaction and excess dimethyl carbonate were removed by reducing the pressure at the vent port to -0.092 MPa. The resin coming out as a strand from the die provided at the exit of the extruder was cooled in a water tank and then pelletized with a pelletizer to obtain an imidized MS resin (2) having a reduced acid value.

  Further, the imidized MS resin (2) is applied to a meshing type co-rotating twin screw extruder having a diameter of 15 mm, the set temperature of each temperature control zone of the extruder is 230 ° C., the screw rotation speed is 150 rpm, the supply amount is 1 kg / hr It was put in the condition of. The vent port pressure was reduced to -0.095 MPa, and volatile components such as unreacted auxiliary materials were removed again. The devolatilized imide resin that emerged as a strand from the die provided at the exit of the extruder was cooled in a water tank and then pelletized with a pelletizer to obtain an imidized MS resin (3).

  The imidized MS resin (3) includes a glutamylimide unit represented by the general formula (1) described in the above embodiment, and a (meth) acrylic acid ester unit represented by the general formula (2). It corresponds to a glutarimide resin copolymerized with an aromatic vinyl unit represented by the general formula (3).

  For the imidized MS resin (3), the imidization ratio and the glass transition temperature were measured according to the above methods. As a result, the imidation ratio was 70 mol%, and the glass transition temperature was 140 ° C.

[Production Example 2]
Imidization in the same manner as in Production Example 1 except that the raw material resin is a methyl methacrylate polymer having a molecular weight of 105,000 (hereinafter also referred to as “PMMA”), and the monomethylamine of the imidizing agent is changed to 2 parts by weight. PMMA resin (3) was obtained. As a result, the imidation ratio was 14 mol% and the glass transition temperature was 127 ° C.

[Example 1]
The imidized MS resin (3) obtained in Production Example 1 was dried at 100 ° C. for 5 hours, and then extruded at 260 ° C. using a 40 mmφ single-screw extruder and a 400 mm wide T-die. The molten resin was cooled with a cooling roll to obtain an unstretched film having a width of 300 mm and a thickness of 150 μm.

  About this film, the biaxially stretched film was created on condition of Table 1 using the laboratory stretcher (Batch type uniaxial stretching apparatus, a hot-air circulation type, a slit nozzle spraying up and down, temperature distribution +/- 1 degreeC). Table 1 shows the mechanical and optical properties of this biaxially stretched film.

[Examples 2-3]
A biaxially stretched film was prepared in the same manner as in Example 1 except that the stretching conditions were changed, and the mechanical properties and optical properties of the obtained biaxially stretched film were measured. Table 1 shows the stretching conditions and the mechanical and optical properties of the biaxially stretched film.

Example 4
A biaxially stretched film was prepared in the same manner as in Example 1 except that the PMMA imidized resin (3) obtained in Production Example 1 was used and the stretching conditions were changed. The mechanical and optical properties were measured. Table 1 shows the stretching conditions and the mechanical and optical properties of the biaxially stretched film.

[Comparative Examples 1-6]
A biaxially stretched film was prepared in the same manner as in Example 1 except that the stretching conditions were changed, and the mechanical properties and optical properties of the obtained biaxially stretched film were measured. Table 1 shows the stretching conditions and the mechanical and optical properties of the biaxially stretched film.

[Comparative Example 7]
A biaxially stretched film was prepared in the same manner as in Example 1 except that the PMMA imidized resin (3) obtained in Production Example 1 was used and the stretching conditions were changed. The mechanical and optical properties were measured. Table 1 shows the stretching conditions and the mechanical and optical properties of the biaxially stretched film.

  Note that the present invention is not limited to the configurations described above, and various modifications are possible within the scope of the claims, and technical means disclosed in different embodiments and examples respectively. Embodiments and examples obtained by appropriately combining them are also included in the technical scope of the present invention.

Claims (5)

A first-axis stretching step of stretching an unstretched film containing an acrylic resin at a stretching ratio of 150% or more, a stretching speed of 5 times / min or more, and a temperature lower by 5 ° C. than the glass transition temperature of the film, and a stretching ratio 150% or more, a stretching speed of 10 times / min or less, and a glass transition temperature of the film or more, including a glass transition temperature of the film + a second axis stretching step of stretching at a temperature within 10 ° C.
The stretching temperature of the second axis is not less than the stretching temperature of the first axis and not more than 10 ° C. of the first axis, and the stretching speed of the first axis is not less than 1.5 times and not more than 7 times the stretching speed of the second axis. A method for producing an acrylic protective film, comprising: The manufacturing method according to claim 1 , wherein the acrylic resin protective film does not contain a rubber component. The method according to claim 1 or 2 , wherein the acrylic resin is any one of a lactone resin, a glutaric anhydride resin, and a glutarimide resin. Glutarimide resin is represented by the following general formula (1)

(Wherein R ¹ and R ² are each independently hydrogen or an alkyl group having 1 to 8 carbon atoms, and R ³ is an alkyl group having 1 to 18 carbon atoms or a cycloalkyl having 3 to 12 carbon atoms. Or a substituent containing an aromatic ring having 5 to 15 carbon atoms.)
And the following general formula (2)

(In the formula, R ⁴ and R ⁵ are each independently hydrogen or an alkyl group having 1 to 8 carbon atoms, and R ⁶ is an alkyl group having 1 to 18 carbon atoms or a cycloalkyl having 3 to 12 carbon atoms. group or process according to claim 3, characterized in that it comprises a unit represented by a.) a substituent containing an aromatic ring having 5 to 15 carbon atoms. Glutarimide resin is represented by the following general formula (3)

(Wherein R ⁷ is hydrogen or an alkyl group having 1 to 8 carbon atoms, and R ⁸ is an aryl group having 6 to 10 carbon atoms.)
The production method according to claim 4 , further comprising a unit represented by: