Resin composition, resin film, polarizing plate and liquid crystal display panel

Abstract

To provide a resin composition having high heat resistance and capable of suppressing sticking to a cast roll during film formation.SOLUTION: The resin composition contains an acrylic resin, has a 5% weight loss temperature of 340 °C. or higher, and has a thickness of 20 μm or more and 500 μm or less. The acrylic resin has a methyl methacrylate unit content of 98% by weight or more, a triad syndiotacticity of 55% or more and 70% or less, and a weight average molecular weight of 80000 or more and 200,000 or less. After a cylindrical probe made of stainless steel having a dia. of 120mm is brought into contact with a non-oriented film having a thickness of 160 μm under the conditions of an entering speed of 200gf / min, a pressurizing force of 1sec, a pressurizing time of 120mm, a separating speed of 5mm / min and a temp. of 150 °C, the peak tack force generated at the time of peeling is 620gf or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a resin composition, a resin film, a polarizing plate, and a liquid crystal display panel. [Background technology]

[0002] Acrylic resins have excellent transparency, color tone, appearance, heat resistance, and processability, and are therefore used, for example, in polarizer protective films (see, for example, Patent Document 1). Here, the polarizer protective films are attached to both sides of a polarizer to form polarizing plates, which are then placed on both sides of a liquid crystal cell to be used in liquid crystal panels. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2017-25333 Summary of the Invention [Problem to be solved by the invention]

[0004] Here, due to increasing demand for larger polarizer protective films and reduced production costs, it has become important to increase the take-up speed during film formation. However, when a film is formed by a melting process, the acrylic resin is depolymerized, and if the take-up speed of the polarizer protective film is increased, the polarizer protective film is likely to stick to the casting roll. As a result, wrinkles and uneven film thickness occur, resulting in a decrease in the quality of the polarizer protective film. In this case, the depolymerized components of the acrylic resin follow the irregularities present on the surface of the casting roll, and the anchor effect makes it more likely that the polarizer protective film will stick to the casting roll.

[0005] An object of the present invention is to provide a resin composition that has high heat resistance and can suppress sticking to a casting roll during film formation. [Means for solving the problem]

[0006] [1] A resin composition containing an acrylic resin, the 5% weight loss temperature of which is 340°C or higher, wherein the acrylic resin has a methyl methacrylate unit content of 98% by weight or higher, a triad syndiotacticity of 55% to 70% and a weight average molecular weight of 80,000 to 200,000, and wherein the peak tack force generated when peeling off a 160 μm thick unstretched film obtained by extrusion molding of the resin composition after contacting a 5 mm diameter stainless steel cylindrical probe with the film under the following conditions: an intrusion speed of 120 mm / min, a pressure of 200 gf, a pressure time of 1 sec, a peeling speed of 120 mm / min and a temperature of 150°C.

[0007] [2] The resin composition according to [1], which has a glass transition temperature of 118°C or higher.

[0008] [3] The resin composition according to [1] or [2], which has a thermal weight loss rate of 1.00% or less when held at 280°C for 30 minutes in a nitrogen stream.

[0009] [4] The resin composition according to any one of [1] to [3], which has a melt flow rate of 7.0 g / 10 min or more and less than 10.0 g / 10 min at a temperature of 230°C and a load of 10 kg.

[0010] [5] The resin composition according to any one of [1] to [4], which contains an antioxidant and optionally contains an ultraviolet absorber, the ratio of the antioxidant to the acrylic resin being 0.2% by weight or more and 1.5% by weight or less, and the ratio of the total amount of the antioxidant and the ultraviolet absorber to the acrylic resin being 0.8% by weight or more and 1.7% by weight or less.

[0011] [6] The resin composition according to [5], wherein the antioxidant is a hindered phenol-based antioxidant.

[0012] [7] The resin composition according to [5] or [6], wherein the antioxidant has a molecular weight of 500 or more.

[0013] [8] The resin composition according to any one of [5] to [7], wherein the ultraviolet absorber is a triazine-based ultraviolet absorber or a benzotriazole-based ultraviolet absorber.

[0014] [9] The resin composition according to any one of [5] to [8], wherein the ultraviolet absorber has a molecular weight of 500 or more.

[0015]

[10] A resin film obtained by molding the resin composition according to any one of [1] to [9].

[0016]

[11] The resin film according to

[10] , having a thickness of 20 μm or more and 500 μm or less.

[0017]

[12] The resin film according to

[10] or

[11] , which is a polarizer protective film.

[0018]

[13] A polarizing plate comprising the resin film according to

[12] .

[0019]

[14] A liquid crystal display panel comprising the polarizing plate according to

[13] . [Effects of the Invention]

[0020] According to the present invention, it is possible to provide a resin film that has high heat resistance and can be prevented from sticking to a casting roll during film formation. DETAILED DESCRIPTION OF THE INVENTION

[0021] Hereinafter, an embodiment of the present invention will be described.

[0022] (Resin composition) The resin composition of the present embodiment contains an acrylic resin.

[0023] In this specification and claims, acrylic resin refers to a polymer of a monomer having an acryloyl group and / or a monomer having a methacryloyl group. In this case, the acrylic resin may be either a homopolymer or a copolymer. When the acrylic resin is a copolymer, it may also be a copolymer of a monomer not having an acryloyl group or a methacryloyl group.

[0024] The syndiotacticity of the acrylic resin, expressed as a triad, is 55% or more, preferably 56% or more, more preferably 57% or more, and even more preferably 58% or more. Since the syndiotacticity of the acrylic resin, expressed as a triad, is 55% or more, the heat resistance of the resin composition of this embodiment is improved.

[0025] The syndiotacticity of the acrylic resin, expressed as a triad, is 70% or less, preferably 67% or less, more preferably 65% ​​or less, and even more preferably 60% or less. Since the syndiotacticity of the acrylic resin, expressed as a triad, is 70% or less, the extrusion molding processability of the resin composition of this embodiment is improved.

[0026] The syndiotacticity of acrylic resin triads is the proportion of three structural unit sequences (triads) that are rr. In addition, in two structural unit sequences (diads), those with the same configuration are called meso (m) and those with the opposite configuration are called racemo (r).

[0027] The weight-average molecular weight of the acrylic resin is 80,000 or more and 200,000 or less, and preferably 90,000 or more and 150,000 or less. Since the weight-average molecular weight of the acrylic resin is 80,000 or more and 200,000 or less, the extrusion molding processability of the resin composition of this embodiment is improved.

[0028] The polydispersity of the acrylic resin (ratio of weight average molecular weight to number average molecular weight) is preferably 1.6 to 2.5, more preferably 1.7 to 2.0. When the polydispersity of the acrylic resin is 1.6 to 2.5, the extrusion moldability of the resin composition of this embodiment is improved.

[0029] The glass transition temperature of the resin composition of this embodiment is preferably 118° C. or higher, more preferably 119° C. or higher, even more preferably 120° C. or higher, even more preferably over 120° C., particularly preferably 122° C. or higher, and particularly preferably 123° C. or higher. When the glass transition temperature of the resin composition of this embodiment is 118° C. or higher, the heat resistance of the resin composition of this embodiment is increased.

[0030] The glass transition temperature of the resin composition of this embodiment is preferably 127° C. or lower, more preferably 126° C. or lower, and even more preferably 125° C. or lower. When the resin composition of this embodiment has a glass transition temperature of 127° C. or lower, depolymerization of the acrylic resin is suppressed during extrusion molding of the resin composition of this embodiment.

[0031] The 5% weight loss temperature of the resin composition of this embodiment is 340°C or higher, and preferably 343°C or higher. Because the 5% weight loss temperature of the resin composition of this embodiment is 340°C or higher, depolymerization of the acrylic resin is suppressed during extrusion molding of the resin composition of this embodiment, and as a result, sticking of the resin composition of this embodiment to a casting roll during film formation is suppressed. The 5% weight loss temperature of the resin composition of this embodiment is, for example, 360°C or lower.

[0032] The peak tack strength of the resin composition of this embodiment is 620 gf or less, preferably 610 gf or less, more preferably 600 gf or less, and even more preferably 585 gf or less. Since the peak tack strength of the resin composition of this embodiment is 620 gf or less, the resin composition of this embodiment is prevented from sticking to a casting roll during film formation. The peak tack strength of the resin composition of this embodiment is, for example, 400 gf or more.

[0033] Here, the peak value of the tackiness of the resin composition of this embodiment is the peak value of the tackiness that occurs when a 5 mm diameter stainless steel cylindrical probe is brought into contact with a 160 μm thick unstretched film obtained by extrusion molding of the resin composition of this embodiment and then peeled off under the following conditions: an intrusion speed of 120 mm / min, a pressure of 200 gf, a pressure time of 1 sec, a peeling speed of 120 mm / min, and a temperature of 150° C. 1 gf corresponds to 9.8 mN.

[0034] The resin composition of this embodiment preferably exhibits a weight loss upon heating of 1.00% or less, more preferably 0.80% or less, even more preferably 0.60% or less, and even more preferably 0.57% or less, when held under a nitrogen stream at 280°C for 30 minutes. When the resin composition of this embodiment exhibits a weight loss upon heating of 1.00% or less when held under a nitrogen stream at 280°C for 30 minutes, depolymerization of the acrylic resin during extrusion molding of the resin composition of this embodiment is suppressed, thereby suppressing adhesion of the resin composition to a casting roll during film formation. The resin composition of this embodiment exhibits a weight loss upon heating of 0.30% or more, when held under a nitrogen stream at 280°C for 30 minutes.

[0035] The resin composition of this embodiment preferably has a melt flow rate of 7.0 g / 10 min or more and less than 10.0 g / 10 min at a temperature of 230° C. and a load of 10 kg, more preferably 7.5 g / 10 min or more and less than 10.0 g / 10 min, and even more preferably 7.5 g / 10 min or more and less than 9.5 g / 10 min. When the resin composition of this embodiment has a melt flow rate of 7.0 g / 10 min or more at a temperature of 230° C. and a load of 10 kg, the extrusion molding processability of the resin composition of this embodiment is improved, and when the melt flow rate is less than 10.0 g / 10 min, the resin composition of this embodiment is prevented from sticking to a casting roll during film formation.

[0036] The resin composition of this embodiment preferably contains an antioxidant and optionally contains an ultraviolet absorber. That is, the resin composition of this embodiment may or may not contain an ultraviolet absorber. Here, the antioxidant not only suppresses depolymerization of the acrylic resin during extrusion molding of the resin composition of this embodiment, but also functions as a mold release agent, thereby suppressing sticking of the resin composition of this embodiment to a casting roll during film formation. Furthermore, the ultraviolet absorber functions as a mold release agent, thereby suppressing sticking of the resin composition of this embodiment to a casting roll during film formation.

[0037] The ratio of the antioxidant to the acrylic resin is preferably 0.2 to 1.5% by weight, more preferably 0.3 to 1.0% by weight. When the ratio of the antioxidant to the acrylic resin is 0.2 to 1.5% by weight, the resin composition of this embodiment is prevented from sticking to a casting roll during film formation.

[0038] The ratio of the total amount of antioxidant and UV absorber to the acrylic resin is preferably 0.8 to 1.7% by weight, more preferably 0.8 to 1.5% by weight, and even more preferably 1.0 to 1.2% by weight. When the ratio of the total amount of antioxidant and UV absorber to the acrylic resin is 0.8 to 1.7% by weight, the resin composition of this embodiment is prevented from sticking to a casting roll during film formation.

[0039] (antioxidant) The antioxidant is not particularly limited as long as it can prevent the resin composition of this embodiment from sticking to a casting roll during film formation. Examples of the antioxidant include phosphorus-based antioxidants, hindered phenol-based antioxidants, and thioether-based antioxidants, and two or more of them may be used in combination. Among these, hindered phenol-based antioxidants are preferred from the viewpoint of preventing deterioration of optical properties due to coloration. Examples of hindered phenol-based antioxidants include pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate].

[0040] The hindered phenol-based antioxidant preferably has an acryloyl group and / or a methacryloyl group. During extrusion molding of the resin composition of this embodiment, the terminal of the acrylic resin bonds with the acryloyl group and / or methacryloyl group of the hindered phenol-based antioxidant, thereby suppressing bleed-out of the hindered phenol-based antioxidant during film formation of the resin composition of this embodiment.

[0041] Examples of hindered phenol antioxidants having an acryloyl group and / or a methacryloyl group include 2-tert-butyl-6-(3'-tert-butyl-5'-methyl-hydroxybenzyl)-4-methylphenyl acrylate and 2,4-di-tert-amyl-6-(3',5'-di-tert-amyl-2'-hydroxy-α-methylbenzyl)phenyl acrylate. Among these, 2,4-di-tert-amyl-6-(3',5'-di-tert-amyl-2'-hydroxy-α-methylbenzyl)phenyl acrylate is preferred.

[0042] The phosphorus-based antioxidant preferably has an aromatic functional group with large steric hindrance. The phosphorus-based antioxidant has the effect of suppressing decomposition of the resin during extrusion molding of the resin composition of this embodiment by bonding the phosphorus element with oxygen. If the aromatic functional group of the phosphorus-based antioxidant has large steric hindrance, the antioxidant becomes less likely to move within the resin, and bleeding out is suppressed during film formation of the resin composition of this embodiment.

[0043] Examples of phosphorus-based antioxidants include tris(2,4-di-tert-butylphenyl)phosphite, bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite, 2,2'-methylenebis(4,6-di-tert-butylphenyl)2-ethylhexyl phosphite, etc. Among these, bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite is preferred.

[0044] The molecular weight of the antioxidant is preferably 500 or more, more preferably 550 or more, and even more preferably 600 or more. When the molecular weight of the antioxidant is 500 or more, bleeding out of the antioxidant is suppressed during film formation of the resin composition of this embodiment. The molecular weight of the antioxidant is, for example, 1500 or less.

[0045] (ultraviolet absorber) The ultraviolet absorber is not particularly limited as long as it can prevent the resin composition of this embodiment from sticking to the casting roll during film formation, but examples thereof include benzophenone-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, triazine-based ultraviolet absorbers, salicylic acid-based ultraviolet absorbers, cyanoacrylate-based ultraviolet absorbers, anilide oxalate-based ultraviolet absorbers, malonic acid ester-based ultraviolet absorbers, and formamidine-based ultraviolet absorbers, and two or more of them may be used in combination.Among these, triazine-based ultraviolet absorbers and benzotriazole-based ultraviolet absorbers are preferred from the viewpoints of stability, ultraviolet absorption ability, heat resistance, and solubility. Examples of triazine-based ultraviolet absorbers include 2,4,6-tris(2-hydroxy-4-hexyloxy-3-methylphenyl)-1,3,5-triazine, 2,4,6-tris(4-butoxy-2-hydroxyphenyl)-1,3,5-triazine, 2,4,6-tris(4-hexyloxy-2-hydroxy-3-methylphenyl)-1,3,5-triazine, and 2,4-bis[4-(2-ethylhexyloxy)-2-hydroxyphenyl]-6-(4-methoxyphenyl)-1,3,5-triazine. Examples of benzotriazole-based ultraviolet absorbers include 2,2'-mesitylenebis[6-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol].

[0046] The molecular weight of the ultraviolet absorber is preferably 500 or more, more preferably 550 or more, and even more preferably 600 or more. When the molecular weight of the ultraviolet absorber is 500 or more, bleeding out of the ultraviolet absorber is suppressed during film formation of the resin composition of this embodiment. The molecular weight of the ultraviolet absorber is, for example, 1000 or less. When two or more ultraviolet absorbers are used in combination, the above molecular weight means the average molecular weight of the two or more ultraviolet absorbers.

[0047] (acrylic resin) The acrylic resin has a syndiotacticity of 55% or more, expressed as a triad, and the content of methyl methacrylate units in the acrylic resin is 98% by weight or more, preferably 99% by weight or more, and more preferably 100% by weight. Since the content of methyl methacrylate units in the acrylic resin is 98% by weight or more, the chemical recyclability of the acrylic resin is enhanced. Here, the content of methyl methacrylate units is a value excluding the weight of terminal structures derived from initiators, etc.

[0048] The synthesis method for an acrylic resin having a triad syndiotacticity of 55% or more is not particularly limited, but examples include anionic polymerization and radical polymerization. Among these, radical polymerization is preferred from an environmental perspective (see, for example, International Publication No. 2023 / 238886). Here, the glass transition temperature and triad syndiotacticity of the acrylic resin can be controlled by the polymerization temperature of the acrylic resin. For example, by lowering the polymerization temperature of the acrylic resin, the glass transition temperature and syndiotacticity of the acrylic resin can be increased. The glass transition temperature of the acrylic resin can also be controlled by the molecular weight of the acrylic resin.

[0049] Monomers other than methyl methacrylate that can be used when synthesizing an acrylic resin having a triad syndiotacticity of 55% or more are not particularly limited, but examples include alkyl acrylates such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate; aryl acrylates such as phenyl acrylate; cycloalkyl acrylates such as cyclohexyl acrylate and norbornenyl acrylate; alkyl methacrylates other than methyl methacrylate such as ethyl methacrylate, propyl methacrylate, and butyl methacrylate; aryl methacrylates such as phenyl methacrylate; cycloalkyl methacrylates such as cyclohexyl methacrylate and norbornenyl methacrylate; aromatic vinyl compounds such as styrene and α-methylstyrene; acrylamide; methacrylamide; acrylonitrile; and methacrylonitrile.

[0050] (Other resins) The resin composition of this embodiment may further contain a resin other than an acrylic resin, such as a styrene resin (e.g., acrylonitrile-styrene resin, styrene-maleic anhydride resin), a fluororesin (e.g., polycarbonate, polyvinyl acetal, cellulose acylate, polyvinylidene fluoride, polyfluorinated alkyl (meth)acrylate), a silicone resin, a polyolefin, polyethylene terephthalate, or polybutylene terephthalate.

[0051] (Anti-blocking agent) The resin composition of this embodiment may further contain an antiblocking agent. This increases the blocking resistance of the resin composition of this embodiment. Examples of the antiblocking agent include crosslinked acrylic particles. The volume average particle size of the antiblocking agent is, for example, 0.1 μm or more and 2.5 μm or less. The content of the antiblocking agent in the resin composition of this embodiment is, for example, 1.0 wt % or less.

[0052] (Other additives) The resin composition of the present embodiment may further contain additives such as a light stabilizer, a heat stabilizer, a matting agent, a light diffusing agent, a colorant, a dye, a pigment, an antistatic agent, a heat ray reflecting material, a lubricant, a plasticizer, a stabilizer, a flame retardant, a release agent, a polymer processing aid, and a filler.

[0053] (Method of producing resin composition) The resin composition of this embodiment can be produced by a known method. An example of the method for producing the resin composition of this embodiment will be described below.

[0054] First, an antioxidant (and an ultraviolet absorber) is added to an acrylic resin using a twin-screw extruder equipped with a die at the outlet, and the mixture is kneaded. Next, the strands extruded from the die are cooled in a water tank and then pelletized in a pelletizer to obtain the acrylic resin composition of the present embodiment.

[0055] (resin film) The resin film of the present embodiment is obtained by molding the resin composition of the present embodiment, and may be either a non-stretched film or a stretched film.

[0056] The thickness of the resin film of this embodiment is preferably 20 μm or more and 500 μm or less, and more preferably 50 μm or more and 400 μm or less. When the thickness of the resin film of this embodiment is 20 μm or more and 500 μm or less, the film formation stability of the resin film of this embodiment is improved.

[0057] (Application) The resin film of this embodiment can be applied to, for example, transportation equipment, solar cell components, civil engineering and construction components, daily necessities, electrical and electronic devices, optical components, and medical supplies, but is preferably used as a polarizer protective film. In this case, the resin film of this embodiment is attached to a polarizer to form a polarizing plate. The polarizing plate can be applied to, for example, a liquid crystal display panel or an organic EL display panel.

[0058] (Method of manufacturing resin film) The resin film of this embodiment can be produced by a known method, and an example of the method for producing the resin film of this embodiment will be described below.

[0059] First, the acrylic resin composition of the present embodiment is melted using a twin-screw extruder equipped with a T-die at the outlet, and the sheet extruded from the T-die is cooled with a cooling roll to obtain an unstretched film. Next, the unstretched film is biaxially stretched to obtain a stretched film. In this case, the biaxial stretching may be simultaneous biaxial stretching or sequential biaxial stretching.

[0060] The temperature when biaxially stretching the unstretched film is preferably (Tg + 5)°C or higher and (Tg + 30)°C or lower, more preferably (Tg + 6)°C or higher and (Tg + 25)°C or lower, and even more preferably (Tg + 7)°C or higher and (Tg + 20)°C or lower, where Tg is the glass transition temperature of the acrylic resin composition of this embodiment. The areal stretching ratio when biaxially stretching the unstretched film is not particularly limited, but is, for example, 2 times or higher and 10 times or lower. The stretching speed when biaxially stretching the unstretched film is not particularly limited, but is, for example, 1.1 times / min or higher and 100 times / min or lower. When sequentially biaxially stretching the unstretched film, the stretching speed in the first stage and the stretching speed in the second stage may be the same or different. In the sequential biaxial stretching, the first stage of stretching is usually stretching in the machine direction (MD), and the second stage of stretching is stretching in the width direction (TD).

[0061] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and the above-described embodiments may be modified as appropriate within the scope of the spirit of the present invention. [Example]

[0062] Examples of the present invention will be described below, but the present invention is not limited to these examples.

[0063] (polymerization conversion rate) The polymerization conversion rate [%] was calculated by the weight ratio of the solid content of the polymerization solution to the weight of the charged monomers using a gravimetric method. The solid content of the polymerization solution was calculated by drying the polymerization solution in an oven set at 150°C for 30 minutes.

[0064] (Syndiotacticity rr in triplicate display) Using a 400MHz nuclear magnetic resonance spectrometer AVANCEIII (manufactured by Bruker), the acrylic resin was measured in a deuterated chloroform solution at 22°C with 16 cycles of accumulation. 1 The H-NMR spectrum was measured. Next, the area (X) of the region from 0.60 to 0.95 ppm and the area (Y) of the region from 0.60 to 1.25 ppm were measured when tetramethylsilane (TMS) was set to 0 ppm, and then the area was calculated using the formula (X / Y)×100 The syndiotacticity rr of the triad was calculated by the following formula.

[0065] (Weight average molecular weight Mw and molecular weight dispersity Mw / Mn) The weight-average molecular weight Mw and molecular weight dispersity Mw / Mn of the acrylic resin were calculated using a high-speed GPC system HLC-8220GPC (manufactured by Tosoh Corporation) in terms of standard polystyrene. Specifically, the analysis was carried out under the following conditions using a sample solution prepared by dissolving 20 mg of acrylic resin in 10 mL of chloroform. Detector: RI detector Solvent: Chloroform Guard column: KF-G 4A (manufactured by Resonac) Analytical column: Resonaq KF-806M and KF-806L connected in series Measurement temperature: 40℃ Standard material: Standard polystyrene (manufactured by Tosoh)

[0066] (glass transition temperature Tg) First, to remove residual monomers and decomposition products of the polymerization initiator from the acrylic resin, the resin composition was heat-treated using a thermogravimetric and differential thermal analyzer STA7200 (Hitachi High-Tech Science Co., Ltd.). Specifically, the resin composition was heated from 40°C to 270°C at a rate of 10°C / min under a nitrogen flow of 200 mL / min, and then held at 270°C for 2.0 to 2.5 minutes.

[0067] Next, the glass transition temperature of the resin composition was measured using a differential scanning calorimeter DSC7000X (Hitachi High-Tech Science). Specifically, the resin composition was first heated from 40°C to 160°C at a heating rate of 10°C / min under a nitrogen gas flow of 40 mL / min, cooled to 40°C, and then heated from 40°C to 160°C at a heating rate of 10°C / min. Next, the glass transition temperature Tg (midpoint glass transition temperature) was read from the DSC curve measured during the second heating. Here, the midpoint glass transition temperature is the temperature at the point where the stepwise change in the glass transition of the DSC curve intersects with a line equidistant along the vertical axis from both a line obtained by extrapolating the baseline before the inflection point of the DSC curve to the higher temperature side and a line obtained by extrapolating the baseline after the inflection point of the DSC curve to the lower temperature side.

[0068] (5% weight loss temperature Td5) Using a STA7200 thermogravimetric differential thermal analyzer (Hitachi High-Tech Science), 5 mg of the resin composition was heated from 40°C to 190°C at a rate of 10°C / min under a nitrogen atmosphere, cooled to 40°C at a rate of 5°C / min, and then heated from 40°C to 500°C at a heating rate of 10°C / min, and the 5% weight loss temperature Td5 [°C] was determined.

[0069] (Heating weight reduction rate) The weight loss rate of the resin composition was evaluated using a STA7200 thermogravimetric simultaneous differential thermal analyzer (Hitachi High-Tech Science). First, to remove residual monomers and decomposition products of the polymerization initiator in the acrylic resin, the resin composition was heat-treated by increasing the temperature from 40°C to 270°C at a rate of 10°C / min under a nitrogen flow of 200 mL / min and holding at 270°C for 2.0 to 2.5 minutes. Next, the resin composition was cooled to 40°C, increased the temperature from 40°C to 280°C at a rate of 10°C / min, and then held at 280°C for 30 minutes, and the weight change of the resin composition was recorded. The weight of the resin composition when it reached 280°C was X0 [mg], and the weight of the resin composition when it was held at 280°C for 15 minutes was X [mg]. 15 [mg], the formula [(X0-X 15 ) / X0]×100 The rate of weight loss on heating of the resin composition was calculated by the above method.

[0070] (Melt Flow Rate MFR) The melt flow rate MFR of the resin composition was measured using a melt flow index tester No. 120-FWP (manufactured by Yasuda Seiki Seisakusho) under conditions of a temperature of 230°C and a load of 10 kg.

[0071] (Peak tack strength) A 160 μm-thick unstretched film was dried in a vacuum at 90°C for 2 hours, and then the top surface was wiped with a Kimwipe. Next, using a tacking tester TAC-II (manufactured by RHESCA), a 5 mm diameter stainless steel cylindrical probe was brought into contact with the unstretched film and the peak tack force generated during peeling was measured under the following conditions: penetration speed 120 mm / min, pressure 200 gf, pressure time 1 sec, peeling speed 120 mm / min, and temperature 150°C. The peak tack force was measured 10 times and the average value was calculated.

[0072] (Total light transmittance) The total light transmittance of the stretched film was measured using a haze meter HZ-V3 (manufactured by Suga Test Instruments) in accordance with JIS K7361-1:1997.

[0073] (Hayes) The haze of the stretched film was measured using a haze meter HZ-V3 (manufactured by Suga Test Instruments) in accordance with JIS K7136: 2000. In addition, after sandwiching the biaxially stretched film between glycerin and glass in that order, the internal haze of the stretched film was measured using a haze meter HZ-V3 (manufactured by Suga Test Instruments) in accordance with JIS K7136: 2000.

[0074] (Yellowness YI) The yellowness index YI of the stretched film was measured using a color meter SC-P (manufactured by Suga Test Instruments) in accordance with JIS K7373:2006.

[0075] (Transmittance of light with a wavelength of 380 nm) The ultraviolet-visible absorption spectrum of the stretched film was measured using an ultraviolet-visible spectrophotometer V-560 (manufactured by JASCO Corporation), and the transmittance of light with a wavelength of 380 nm was determined.

[0076] (sticking resistance) The unstretched films were rated as "good" if they did not stick to the casting roll, and "poor" if they stuck to the casting roll and / or were wrinkled.

[0077] (Production of acrylic resin A) A 5L glass reactor equipped with an H-shaped impeller stirrer was charged with 150 parts by weight of deionized water, 0.20 parts by weight of tribasic calcium phosphate (as a dispersant), 0.0075 parts by weight of sodium α-olefin sulfonate, and 0.30 parts by weight of sodium chloride. Next, under a nitrogen atmosphere, 100 parts by weight of methyl methacrylate (MMA), 0.289 parts by weight of n-octyl mercaptan (as a chain transfer agent), and 0.074 parts by weight of 2,2'-azobis(isobutyrate) dimethyl V-601 (Fujifilm Wako Pure Chemical Industries, Ltd.) (as a polymerization initiator) were added to the reactor while stirring at 250 rpm. The liquid temperature in the reactor was then raised to 70°C to initiate polymerization. Two hours after the start of polymerization, 0.10 parts by weight of tribasic calcium phosphate was added to the polymerization solution. An exothermic peak associated with the gel effect was observed 4 hours and 20 minutes after the start of polymerization. Seven hours after the start of polymerization, the temperature was raised to 95°C. Two hours after the temperature reached 95°C, the reactor was cooled to room temperature to terminate the polymerization, yielding an acrylic resin dispersion. At this time, the polymerization conversion rate was 99%. The acrylic resin dispersion was then washed with 1N hydrochloric acid in an amount 0.1 times by weight of the charged monomer, followed by washing with water to remove the dispersant. The washed acrylic resin was then dehydrated and dried to yield acrylic resin A in the form of beads. Acrylic resin A had an MMA unit content of 100% by weight, an rr of 58%, an Mw of 115,200, and an Mw / Mn of 1.94.

[0078] (Production of acrylic resin D) Acrylic resin D was produced in the same manner as in Production Example 1 of Japanese Patent No. 6827272. Acrylic resin D had an MMA unit content of 100% by weight, an rr of 74%, an Mw of 97,400, and an Mw / Mn of 1.09.

[0079] Example 1 (Production of Resin Composition) A hand-blended mixture of 100 parts by weight of acrylic resin A with 0.3 parts by weight of antioxidant Sumilizer GS (Sumitomo Chemical) (hereinafter referred to as AO-1) and 0.7 parts by weight of ultraviolet absorber LA-F70 (ADEKA) (hereinafter referred to as UVA-1) was extruded at an extrusion temperature of 253-255°C using a 15mm diameter, L / D=45mm, intermeshing co-rotating twin-screw extruder KZW15TWIN-45MG (Technovel) equipped with a die at the outlet. The extruded strand was then cooled in a water bath, pelletized in a pelletizer, and dried at 90°C for 4 hours to obtain a pelletized resin composition. The resin composition had a Tg of 120°C, a Td5 of 346°C, a heat weight loss of 0.35%, and an MFR of 7.7g / 10min. In this case, AO-1 is 2,4-di-tert-amyl-6-(3',5'-di-tert-amyl-2'-hydroxy-α-methylbenzyl)phenyl acrylate and has a molecular weight of 549. Also, UVA-1 is 2,4,6-tris(2-hydroxy-4-hexyloxy-3-methylphenyl)-1,3,5-triazine and has a molecular weight of 699.

[0080] (Manufacturing of resin films) The resin composition was extruded at an extrusion temperature of 240 to 250°C using a 15mm diameter, L / D=45 intermeshing co-rotating twin-screw extruder (KZW15TWIN-45MG, manufactured by Technovel) equipped with a T-die at the outlet. The sheet extruded from the T-die was then cooled with a cooling roll to obtain an unstretched film with a width of 200mm and a thickness of 160µm. The unstretched film had a peak tack strength of 597gf. A 100mm x 100mm piece was then cut from the unstretched film so that two sides were parallel to the extrusion direction. The piece was then placed in a pantograph-type biaxial stretching device and simultaneously biaxially stretched at a stretching temperature of 135°C and a stretching speed of 100mm / min so that the stretch ratio in the directions parallel and perpendicular to the extrusion direction was 2x. The stretched piece was then removed to room temperature and quenched to obtain a stretched film with a thickness of 40µm.

[0081] Example 2 A stretched film was obtained in the same manner as in Example 1, except that in (Production of Resin Composition), 0.5 parts by weight of antioxidant AO-60 (manufactured by ADEKA) (hereinafter referred to as AO-2) was hand-blended with 100 parts by weight of acrylic resin A. The resin composition had a Tg of 119°C, a Td5 of 343°C, a heat weight loss rate of 0.32%, and an MFR of 8.1 g / 10 min. The unstretched film had a peak tack strength of 557 gf. AO-2 was pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and had a molecular weight of 1178.

[0082] Example 3 A stretched film was obtained in the same manner as in Example 1, except that in (production of resin composition), 1.0 part by weight of AO-1 was hand-blended with 100 parts by weight of acrylic resin A. The resin composition had a Tg of 119°C, a Td5 of 348°C, a heat weight loss rate of 0.57%, and an MFR of 8.4 g / 10 min. The unstretched film also had a peak tack strength of 575 gf.

[0083] Example 4 A stretched film was obtained in the same manner as in Example 1, except that in (Production of Resin Composition), 0.3 parts by weight of AO-1, ​​0.2 parts by weight of AO-2, and 0.7 parts by weight of UVA-1 were hand-blended with 100 parts by weight of acrylic resin A. The resin composition had a Tg of 120°C, a Td5 of 347°C, a heat weight loss rate of 0.39%, and an MFR of 8.4 g / 10 min. The unstretched film also had a peak tack strength of 557 gf.

[0084] Example 5 A stretched film was obtained in the same manner as in Example 1, except that in (Production of Resin Composition), 100 parts by weight of acrylic resin A was hand-blended with 0.3 parts by weight of AO-1, ​​0.2 parts by weight of AO-2, 0.4 parts by weight of UVA-1, and 0.3 parts by weight of an ultraviolet absorber (hereinafter referred to as UVA-2). The resin composition had a Tg of 119°C, a Td5 of 346°C, a heat weight loss of 0.39%, and an MFR of 8.6 g / 10 min. The unstretched film had a peak tack strength of 581 gf. UVA-2 was 2,4,6-tris(4-butoxy-2-hydroxyphenyl)-1,3,5-triazine and had a molecular weight of 574.

[0085] Example 6 A stretched film was obtained in the same manner as in Example 1, except that in (Production of Resin Composition), 0.3 parts by weight of AO-1, ​​0.2 parts by weight of AO-2, and 1.0 part by weight of UVA-2 were hand-blended with 100 parts by weight of acrylic resin A. The resin composition had a Tg of 119°C, a Td5 of 336°C, a heat weight loss rate of 0.77%, and an MFR of 9.6 g / 10 min. The unstretched film also had a peak tack strength of 600 gf.

[0086] Example 7 A stretched film was obtained in the same manner as in Example 1, except that in (Production of Resin Composition), 0.3 parts by weight of AO-1, ​​0.3 parts by weight of AO-3, and 0.7 parts by weight of UVA-1 were hand-blended with 100 parts by weight of acrylic resin A. The resin composition had a Tg of 122°C, a Td5 of 340°C, a thermal weight loss of 0.92%, and an MFR of 8.9 g / 10 min. The unstretched film had a peak tack strength of 590 gf. AO-3 was bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite and had a molecular weight of 633.

[0087] (Comparative Example 1) A stretched film was obtained in the same manner as in Example 1, except that (Production of Resin Composition) was omitted and acrylic resin A was used instead of the resin composition in (Production of Resin Film). Acrylic resin A had a Tg of 120°C, a Td5 of 333°C, a thermal weight loss rate of 0.70%, and an MFR of 6.8 g / 10 min. The unstretched film had a peak tack strength of 787 gf.

[0088] (Comparative Example 2) A stretched film was obtained in the same manner as in Example 1, except that in (Production of resin composition), 0.7 parts by weight of UVA-1 was hand-blended with 100 parts by weight of acrylic resin A. The resin composition had a Tg of 120°C, a Td5 of 335°C, a heat weight loss rate of 0.96%, and an MFR of 7.7 g / 10 min. The unstretched film also had a peak tack strength of 717 gf.

[0089] (Comparative Example 3) A stretched film was obtained in the same manner as in Example 1, except that in (production of resin composition), 0.5 parts by weight of AO-1 was hand-blended with 100 parts by weight of acrylic resin A. The resin composition had a Tg of 120°C, a Td5 of 346°C, a heat weight loss rate of 0.19%, and an MFR of 7.5 g / 10 min. The unstretched film also had a peak tack strength of 731 gf.

[0090] Comparative Example 4 A stretched film was obtained in the same manner as in Example 1, except that in (Production of resin composition), 2.0 parts by weight of AO-1 was hand-blended with 100 parts by weight of acrylic resin A. The resin composition had a Tg of 119°C, a Td5 of 349°C, a heat weight loss rate of 0.89%, and an MFR of 9.0 g / 10 min. The unstretched film also had a peak tack strength of 678 gf.

[0091] (Comparative Example 5) A stretched film was obtained in the same manner as in Comparative Example 1, except that Parapet HR-S (manufactured by Kuraray) (hereinafter referred to as acrylic resin B) was used instead of acrylic resin A. Acrylic resin B had an MMA unit content of 98% by weight or more, rr of 51%, Mw of 122,000, Mw / Mn of 1.89, Tg of 116°C, Td5 of 332°C, a rate of weight loss on heating of 1.12%, and MFR of 8.4 g / 10 min. The unstretched film also had a peak tack strength of 647 gf.

[0092] (Comparative Example 6) A stretched film was obtained in the same manner as in Example 4, except that acrylic resin B was used instead of acrylic resin A. The resin composition had a Tg of 117°C, a Td5 of 343°C, a thermal weight loss of 0.27%, and an MFR of 8.5g / 10min. The unstretched film had a peak tack strength of 660gf.

[0093] (Comparative Example 7) A stretched film was obtained in the same manner as in Comparative Example 1, except that Parapet EH (manufactured by Kuraray) (hereinafter referred to as acrylic resin C) was used instead of acrylic resin A. Acrylic resin C had an MMA unit content of 95% by weight or more, rr of 53%, Mw of 159,800, Mw / Mn of 2.02, Tg of 111°C, Td5 of 338°C, a rate of weight loss on heating of 0.63%, and MFR of 5.3 g / 10 min. The unstretched film had a peak tack strength of 489 gf.

[0094] (Comparative Example 8) A stretched film was obtained in the same manner as in Comparative Example 3, except that acrylic resin C was used instead of acrylic resin A. The resin composition had a Tg of 111°C, a Td5 of 351°C, a thermal weight loss rate of 0.45%, and an MFR of 5.3g / 10min. The unstretched film had a peak tack strength of 534gf.

[0095] (Comparative Example 9) Acrylic resin D was used instead of acrylic resin A. Acrylic resin D had a Tg of 128°C, a Td5 of 343°C, a thermal weight loss rate of 0.01%, and an MFR of 5.8g / 10min. However, a resin film could not be produced.

[0096] Table 1 shows the properties of acrylic resins A to D.

[0097] [Table 1]

[0098] Table 2 shows the evaluation results of the resin composition and the resin film.

[0099] [Table 2]

[0100] Table 2 shows that the resin compositions of Examples 1 to 7 contain acrylic resin A, have a Td5 of 340°C or higher, and a peak tack strength of 620 gf or less, and therefore have high heat resistance and are less likely to stick to the casting roll during film formation. Here, acrylic resin A has an MMA unit content of 100 wt%, an rr of 58%, and an Mw of 115,200. In contrast, the resin compositions of Comparative Examples 1 and 2 have a Td5 of 334 to 336°C and a peak tack strength of 717 to 787 gf, and therefore are more likely to stick to the casting roll during film formation. The resin compositions of Comparative Examples 3 and 4 have a peak tack strength of 678 to 731 gf, and therefore are more likely to stick to the casting roll during film formation. The resin composition of Comparative Example 5 contains acrylic resin B with an rr of 51%, has a Td5 of 332°C, and a peak tack strength of 647 gf, and therefore has low heat resistance and is more likely to stick to the casting roll during film formation. The resin composition of Comparative Example 6 contains acrylic resin B with an rr of 51% and has a peak tack strength of 660 gf, so it has low heat resistance and is prone to sticking to the cast roll during film formation. The resin compositions of Comparative Examples 7 and 8 contain acrylic resin C with an rr of 53%, so they have low heat resistance. The resin composition of Comparative Example 9 contains acrylic resin D with an rr of 74%, so it has low extrusion moldability and a resin film could not be produced.

Claims

1. A resin composition containing an acrylic resin, The 5% weight loss temperature is 340°C or higher, The acrylic resin has a methyl methacrylate unit content of 98% by weight or more, a triad syndiotacticity of 55% to 70% and a weight average molecular weight of 80,000 to 200,000, A resin composition, wherein a tack force of 620 gf or less peak value is generated when a 5 mm diameter stainless steel cylindrical probe is brought into contact with an unstretched film having a thickness of 160 μm and obtained by extrusion molding of the resin composition under the following conditions: an entry speed of 120 mm / min, a pressure of 200 gf, a pressure time of 1 sec, a peeling speed of 120 mm / min, and a temperature of 150°C, and then the film is peeled off.

2. The resin composition according to claim 1, having a glass transition temperature of 118°C or higher.

3. 3. The resin composition according to claim 1, which has a heat weight loss rate of 1.00% or less when held at 280°C for 30 minutes in a nitrogen stream.

4. The resin composition according to claim 1 or 2, which has a melt flow rate of 10.0 g / 10 min or more and less than 9.5 g / 10 min at a temperature of 230° C. and a load of 10 kg.

5. containing an antioxidant and optionally containing an ultraviolet absorber; a ratio of the antioxidant to the acrylic resin of 0.2% by weight or more and 1.5% by weight or less; 3. The resin composition according to claim 1, wherein a ratio of the total amount of the antioxidant and the ultraviolet absorber to the acrylic resin is 0.8% by weight or more and 1.7% by weight or less.

6. The resin composition according to claim 5 , wherein the antioxidant is a hindered phenol-based antioxidant.

7. The resin composition according to claim 5 , wherein the antioxidant has a molecular weight of 500 or more.

8. The resin composition according to claim 5 , wherein the ultraviolet absorber is a triazine-based ultraviolet absorber or a benzotriazole-based ultraviolet absorber.

9. The resin composition according to claim 5 , wherein the ultraviolet absorber has a molecular weight of 500 or more.

10. A resin film obtained by extrusion molding the resin composition according to claim 1 or 2.

11. The resin film according to claim 10, having a thickness of 20 μm or more and 500 μm or less.

12. The resin film according to claim 10 , which is a polarizer protective film.

13. A polarizing plate comprising the resin film according to claim 12.

14. A liquid crystal display panel comprising the polarizing plate according to claim 13.

Images