Method for producing master batch, method for producing acrylic resin composition, and master batch

Abstract

The invention relates to a method for producing a master batch, a method for producing an acrylic resin composition, and a master batch. Provided is a method for producing a master batch by supplying a raw material resin composition to an extruder provided with a cylinder and a screw, the temperature of the cylinder being 200 DEG C or less, the production method satisfying formula (1), the raw material resin composition comprising an acrylic resin and acrylic crosslinked particles having an average particle diameter of 1 [mu] m or less, the content of the acrylic crosslinked particles is 5% by weight or more. (In the formula, Q is the supply speed [kg / h] of the raw material resin composition, N is the rotation speed [rpm] of the screw, and D is the diameter [mm] of the extruder. (1) Q / N / (D / 40) 3 < = 0.11.

Description

Technical Field

[0001] The present invention relates to a method for producing a masterbatch, a method for producing an acrylic resin composition, and the masterbatch. Background Art

[0002] Liquid crystal display devices are usually provided with two polarizing plates on both sides of the liquid crystal unit. Here, the polarizing plate has a polarizer protective film adhered to the surface of the polarizer. As the polarizer protective film, triacetyl cellulose (TAC) film is usually used, and acrylic film has been proposed for the purpose of improving durability. However, acrylic film is prone to blocking due to its high surface smoothness. In order to prevent blocking, there is a known method of passing a resin composition comprising an amorphous acrylic resin (A) having a ring structure in the main chain and particles (B) having an average particle size of 0.1 to 1 μm through a polymer filter in a molten state, and then melt-extruding it into a film (see Patent Document 1).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: International Publication No. 2010 / 061917 Summary of the Invention

[0006] Problems to be solved by the invention

[0007] However, studies by the present inventors have revealed that the method for producing an optical film described in Patent Document 1 increases the number of poorly dispersed particles, and as a result, the pressure difference between the outlet and inlet of the polymer filter may increase.

[0008] An object of the present invention is to provide a method for producing a masterbatch that can reduce poorly dispersed particles.

[0009] Solutions for solving problems

[0010] [1] A method for producing a masterbatch, comprising supplying a raw resin composition to an extruder equipped with a barrel and a screw to produce the masterbatch, wherein the temperature of the barrel is 200° C. or lower, and the method satisfies the following formula (1), wherein the raw resin composition comprises an acrylic resin and acrylic cross-linked particles having an average particle size of 1 μm or lower, and the content of the acrylic cross-linked particles is 5% by weight or higher.

[0011] Q / N / (D / 40) 3 ≤0.11···(1)

[0012] (wherein, Q is the feed rate of the raw resin composition [kg / h], N is the rotational speed of the screw [rpm], and D is the diameter of the extruder [mm].)

[0013] [2] The method for producing a masterbatch according to [1], wherein the raw resin composition further contains an additive having a melting point of 200°C or less.

[0014] [3] The method for producing a masterbatch according to [2], wherein the additive is a lubricant or an ultraviolet absorber.

[0015] [4] The method for producing a masterbatch according to any one of [1] to [3], wherein the acrylic resin has a glass transition temperature of 120° C. or higher.

[0016] [5] The method for producing a masterbatch according to [4], wherein the acrylic resin has a ring structure in its main chain.

[0017] [6] A method for producing an acrylic resin composition, comprising: obtaining a masterbatch by the method for producing a masterbatch according to any one of [1] to [5]; and mixing the masterbatch with an acrylic resin having a ring structure in its main chain.

[0018] [7] A masterbatch comprising an acrylic resin and acrylic cross-linked particles having an average particle size of 1 μm or less, wherein the content of the acrylic cross-linked particles is 5% by weight or more, and the number of particles having a particle size of 10 μm or more per 1 mg of the masterbatch, as measured by dissolving or dispersing the masterbatch in dichloromethane to a solid content concentration of 40 ppm by weight, is 200 or less.

[0019] [8] A masterbatch comprising an acrylic resin having a glass transition temperature of 120°C or higher and acrylic cross-linked particles, wherein the content of the acrylic cross-linked particles is 5% by weight or higher, and the number of particles having a particle size of 10 μm or higher per 1 mg of the masterbatch, as measured by dissolving or dispersing the masterbatch in dichloromethane to a solid content concentration of 40 ppm by weight, is 200 or less.

[0020] [9] The masterbatch according to [7] or [8], wherein the number of particles having a particle size of 10 μm or more and 20 μm or less per 1 mg of the masterbatch, as measured by dissolving or dispersing the masterbatch in dichloromethane to a solid content concentration of 40 ppm by weight, is 120 or less.

[0021]

[10] A masterbatch comprising an acrylic resin and acrylic cross-linked particles having an average particle size of 1 μm or less, wherein the content of the acrylic cross-linked particles is 5% by weight or more, and the number of particles having a particle size of 10 μm or more and 20 μm or less per 1 mg of the masterbatch, as measured by dissolving or dispersing the masterbatch in dichloromethane to a solid content concentration of 40 ppm by weight, is 120 or less.

[0022]

[11] A masterbatch comprising an acrylic resin having a glass transition temperature of 120°C or higher and acrylic cross-linked particles, wherein the content of the acrylic cross-linked particles is 5% by weight or higher, and the number of particles having a particle size of 10 μm or higher and 20 μm or lower per mg of the masterbatch, as measured by dissolving or dispersing the masterbatch in dichloromethane to a solid content concentration of 40 ppm by weight, is 120 or lower.

[0023] Effects of the Invention

[0024] According to the present invention, a method for producing a masterbatch capable of reducing poorly dispersed particles can be provided. DETAILED DESCRIPTION

[0025] Hereinafter, embodiments of the present invention will be described.

[0026] [Masterbatch Manufacturing Method]

[0027] The manufacture method of the masterbatch of the present embodiment is to supply the raw material resin composition to the extruder possessing barrel and screw to manufacture the method for masterbatch.As extruder, it is not particularly limited, for example, can enumerate single screw extruder, twin screw extruder.Below, an example of the manufacture method of the masterbatch of the present embodiment is described.

[0028] First, a raw resin composition is fed from the main feeder of a twin-screw extruder and melted. Next, the strands discharged from the die of the twin-screw extruder are cooled in a water tank and then cut into pieces using a pelletizer to obtain a masterbatch.

[0029] Here, the barrel temperature is 200°C or less, preferably 180°C or less. When the barrel temperature is 200°C or less, the melt viscosity of the raw resin composition is maintained within a certain range, the shear stress is sufficiently applied to the raw resin composition, and the number of poorly dispersed particles in the masterbatch is reduced. As a result, even when the masterbatch is added to produce the acrylic resin composition described later for a long period of time, the pressure difference between the outlet and inlet of the polymer filter located upstream of the extruder die is unlikely to increase. The barrel temperature is, for example, 150°C or more.

[0030] The manufacturing method of the masterbatch of the present embodiment satisfies the following formula (1). Therefore, the shear stress is fully loaded on the raw resin composition, thereby, the poorly dispersed particles in the masterbatch decrease. As a result, even if the masterbatch is added to manufacture the acrylic resin composition described later for a long time, the pressure difference between the outlet and the inlet of the polymer filter provided on the upstream side of the die of the extruder is not easy to rise.

[0031] Q / N / (D / 40) 3 ≤0.11···(1)

[0032] (Wherein, Q is the feed rate of the raw resin composition [kg / h], N is the screw speed [rpm], and D is the extruder diameter [mm].)

[0033] It should be noted that (D / 40) is the diameter of the extruder normalized (dimensionless) using the normalization constant 40 [mm]. Here, Q / N / (D / 40) 3 More preferably, it is 0.1 [kg / h / rpm] or less. In addition, Q / N / (D / 40) 3 For example, it is 0.03 [kg / h / rpm] or more.

[0034] The base resin composition includes an acrylic resin and acrylic crosslinked particles having an average particle size of 1 μm or less. The content of the acrylic crosslinked particles in the base resin composition is 5% by weight or greater, preferably 8% by weight or greater, and more preferably 10% by weight or greater. When the content of the acrylic crosslinked particles in the base resin composition is 5% by weight or greater, the amount of masterbatch added is reduced when producing an acrylic resin composition used in the manufacture of an optical film having excellent blocking resistance. The content of the acrylic crosslinked particles in the base resin composition can be, for example, 30% by weight or less, 25% by weight or less, or 20% by weight or less.

[0035] The raw resin composition preferably further contains an additive with a melting point of 200°C or less. This ensures that the acrylic crosslinked particles are fully wetted before the raw resin composition is kneaded in the extruder, reducing the number of poorly dispersed particles in the masterbatch. Consequently, even when the masterbatch is added to produce the acrylic resin composition described later over a long period of time, the pressure difference between the outlet and inlet of the polymer filter located upstream of the extruder die is unlikely to increase.

[0036] Additives are not particularly limited as long as their melting point is 200°C or less. Examples include lubricants, UV absorbers, and antioxidants. Examples of lubricants include fatty acid amide lubricants, fatty acid ester lubricants, metal soap lubricants, polymer lubricants, aliphatic hydrocarbon lubricants, aliphatic alcohol lubricants, and aliphatic acid lubricants. Specific examples of lubricants include stearic acid amide and palmitic acid amide. UV absorbers include triazine compounds, benzotriazole compounds, benzophenone compounds, and benzoxazine compounds. Specific examples of UV absorbers include 2,4,6-tris(2-hydroxy-4-hexyloxy-3-methylphenyl)-1,3,5-triazine and 2-(4,6-diphenyl-1,3,5-triazine-2-yl)-5-[2-(2-ethylhexanoyloxy)ethoxy]phenol. Examples of the antioxidant include phenolic antioxidants, phosphorus antioxidants, and sulfur antioxidants. Specific examples of the antioxidant include 2,6-di-tert-butyl-p-cresol, tocopherol, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, triphenylphosphite, and tris(2,4-di-tert-butylphenyl)phosphite.

[0037] (Acrylic resin)

[0038] In this specification and claims, an 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 monomers that do not have an acryloyl group or a methacryloyl group.

[0039] The glass transition temperature of the acrylic resin is preferably 120°C or higher, more preferably higher than 120°C, even more preferably 121°C or higher, even more preferably 123°C or higher, and particularly preferably 125°C or higher. A glass transition temperature of 120°C or higher is practically preferable because it minimizes dimensional changes in acrylic films under high-temperature environments. The glass transition temperature of the acrylic resin is, for example, 150°C or lower.

[0040] The acrylic resin having a glass transition temperature of 120° C. or higher is not particularly limited, and examples thereof include acrylic resins having a ring structure in the main chain.

[0041] Here, the ring structure is preferably one or more selected from the group consisting of a glutarimide ring, a lactone ring, a maleic anhydride ring, a maleimide ring, and a glutaric anhydride ring.

[0042] The acrylic resin having a glutarimide ring in the main chain has, for example, a structural unit represented by the following formula (1) as a structural unit having a ring structure in the main chain.

[0043]

[0044] (Where R 1 and R 2 are each independently a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, R 3 is a hydrogen atom, an alkyl group having 1 to 18 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, or an aryl group having 6 to 10 carbon atoms.

[0045] The content of the structural unit represented by formula (1) in the acrylic resin is preferably 2% by weight or more and 30% by weight or less. When the content of the structural unit represented by formula (1) in the acrylic resin is 2% by weight or more, the dimensional change of the acrylic film under a high temperature environment is reduced. When the content is 30% by weight or less, the retardation of the acrylic film is reduced.

[0046] It should be noted that the content of the structural unit represented by formula (1) in the acrylic resin is, for example, 3 In the case of methyl, based on 1 The molar ratio was determined by comparing the peak area of the H-NMR spectrum at around 3.5 to 3.8 ppm derived from the protons of O—CH 3 constituting methyl methacrylate and the peak area of the H-NMR spectrum at around 3.0 to 3.3 ppm derived from the protons of N—CH 3 constituting the glutarimide ring.

[0047] The acrylic resin having the structural unit represented by formula (1) can be produced using a known method. An example of a method for producing the acrylic resin having the structural unit represented by formula (1) will be described below.

[0048] First, a twin-screw extruder is used to melt a methyl methacrylate resin, and an imidizing agent is injected to imidize the methyl methacrylate resin. Then, the strands discharged from the die of the twin-screw extruder are cooled in a water tank and cut with a granulator to obtain an imidized acrylic resin. Next, a twin-screw extruder is used to melt the imidized methyl methacrylate resin, and an esterifying agent is injected to esterify the imidized acrylic resin. Next, the strands discharged from the die of the twin-screw extruder are cooled in a water tank and cut with a granulator to obtain an acrylic resin having a structural unit represented by formula (1).

[0049] Examples of the imidizing agent include primary amines represented by the following formula (2) and ammonia. Among these, monomethylamine is preferred.

[0050] R3 NH2(2)

[0051] (Where R 3 Same meaning as formula (1).

[0052] Examples of the esterifying agent include dimethyl carbonate, 2,2-dimethoxypropane, dimethyl sulfoxide, triethyl orthoformate, trimethyl orthoacetate, trimethyl orthoformate, diphenyl carbonate, dimethyl sulfate, methyl toluenesulfonate, methyl trifluoromethanesulfonate, methyl acetate, methanol, ethanol, methyl isocyanate, p-chlorophenyl isocyanate, dimethylcarbodiimide, dimethyl tert-butylchlorosilane, isopropenyl acetate, dimethylurea, tetramethylammonium hydroxide, dimethyldiethoxysilane, tetra-n-butoxysilane, dimethyl (trimethylsilyl) phosphite, trimethylphosphite, trimethyl phosphate, tricresyl phosphate, diazomethane, ethylene oxide, propylene oxide, cyclohexene oxide, 2-ethylhexyl glycidyl ether, phenyl glycidyl ether, and benzyl glycidyl ether. Among these, dimethyl carbonate is preferred.

[0053] The acrylic resin having a lactone ring in the main chain can be obtained by, for example, polymerizing a monomer represented by the following formula (3) and then heat-treating the polymer to form a lactone ring.

[0054]

[0055] (Where R 4 and R 5 Each independently represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms.)

[0056] Examples of the monomer represented by formula (3) include methyl 2-(hydroxymethyl)acrylate, ethyl 2-(hydroxymethyl)acrylate, isopropyl 2-(hydroxymethyl)acrylate, n-butyl 2-(hydroxymethyl)acrylate, and tert-butyl 2-(hydroxymethyl)acrylate. Two or more monomers may be used in combination. Among these, methyl 2-(hydroxymethyl)acrylate and ethyl 2-(hydroxymethyl)acrylate are preferred, and methyl 2-(hydroxymethyl)acrylate is particularly preferred.

[0057] The acrylic resin may further include a structural unit derived from a (meth)acrylate. Examples of (meth)acrylates include alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, and isobutyl (meth)acrylate; aryl (meth)acrylates such as phenyl (meth)acrylate; aryl (meth)acrylates such as benzyl (meth)acrylate; and cycloalkyl (meth)acrylates such as cyclohexyl (meth)acrylate. Two or more of these may be used in combination. Of these, alkyl methacrylates are preferred, with methyl methacrylate being particularly preferred.

[0058] The acrylic resin may further include structural units derived from other monomers. Examples of the other monomers include, but are not limited to, aromatic monomers such as styrene and methylstyrene; and nitrile monomers such as acrylonitrile and methacrylonitrile.

[0059] Examples of acrylic resins having a maleic anhydride ring in the main chain include styrene-N-phenylmaleimide-maleic anhydride copolymers. Examples of acrylic resins having a maleimide ring in the main chain include olefin-maleimide copolymers described in Japanese Patent Application Laid-Open No. 2004-45893. Examples of acrylic resins having a glutaric anhydride ring in the main chain include heat-resistant copolymers described in Japanese Patent Application Laid-Open No. 2003-137937.

[0060] (Acrylic cross-linked particles)

[0061] In this specification and claims, acrylic crosslinked particles refer to crosslinked particles comprising a polymer of a monomer having an acryloyl group and / or a monomer having a methacryloyl group. In this case, the polymer may be either a homopolymer or a copolymer. When the polymer is a copolymer, it may also be a copolymer of monomers that do not have an acryloyl group or a methacryloyl group.

[0062] The shape of the acrylic crosslinked particles is not particularly limited, but a true spherical shape is preferred in consideration of the blocking resistance of the optical film.

[0063] The ratio of the refractive index of the acrylic crosslinked particles to the refractive index of the acrylic resin is preferably 98% to 102%, more preferably 99% to 101%. When the ratio of the refractive index of the acrylic crosslinked particles to the refractive index of the acrylic resin is 98% to 102%, an optical film with excellent transparency can be obtained. The refractive index of the acrylic crosslinked particles is preferably 1.47 to 1.55, more preferably 1.47 to 1.53, and particularly preferably 1.48 to 1.52. When the refractive index of the acrylic crosslinked particles is 1.47 to 1.55, an optical film with excellent transparency can be obtained.

[0064] The monofunctional monomer used to produce the acrylic crosslinked particles is not particularly limited, and examples thereof include (meth)acrylates and other monofunctional monomers copolymerizable with (meth)acrylates. Among these, methyl methacrylate is preferred from the perspectives of compatibility with acrylic resins and refractive index. The content of methyl methacrylate units in the acrylic crosslinked particles is not particularly limited, and for example, is 80% to 99% by weight.

[0065] When producing acrylic crosslinked particles, a polyfunctional monomer may be used. The weight ratio of the polyfunctional monomer to the monofunctional monomer is preferably 0.5% by weight or greater and 30% by weight or less. When the weight ratio of the polyfunctional monomer to the monofunctional monomer is 0.5% by weight or greater, the heat resistance and dispersibility of the acrylic crosslinked particles are improved. When the weight ratio is 30% by weight or less, the acrylic crosslinked particles are less likely to aggregate and form irregular particles during production.

[0066] The base resin composition contains acrylic crosslinked particles having an average particle size of 1 μm or less, preferably first acrylic crosslinked particles having an average particle size of 0.5 μm to 1.0 μm, and second acrylic crosslinked particles having an average particle size of 0.1 μm to 0.3 μm. The base resin composition containing acrylic crosslinked particles having an average particle size of 1 μm or less can produce an optical film having excellent transparency and anti-blocking properties. The weight ratio of the second acrylic crosslinked particles to the first acrylic crosslinked particles is not particularly limited, but is, for example, 0.10 to 0.50.

[0067] The raw resin composition may contain a plurality of acrylic crosslinked particles having different average particle sizes. In addition, the raw resin composition may further contain acrylic crosslinked particles having an average particle size exceeding 1 μm, as long as the effects of the present invention are not impaired.

[0068] [Method for producing acrylic resin composition]

[0069] The method for producing an acrylic resin composition according to this embodiment includes: obtaining a masterbatch using the method for producing a masterbatch according to this embodiment; and mixing the masterbatch with an acrylic resin having a ring structure in its main chain. The acrylic resin having a ring structure in its main chain mixed with the masterbatch is the same as the acrylic resin having a ring structure in its main chain contained in the raw resin composition. It should be noted that the acrylic resin having a ring structure in its main chain mixed with the masterbatch may be the same as or different from the acrylic resin having a ring structure in its main chain contained in the raw resin composition. An example method for producing an acrylic resin composition is described below.

[0070] First, an acrylic resin having a ring structure in its main chain is fed from the main feeder of a twin-screw extruder and melted. Next, a masterbatch is fed from the side feeder of the twin-screw extruder and mixed with the acrylic resin having a ring structure in its main chain while simultaneously melting. The strands discharged from the die of the twin-screw extruder are then cooled in a water tank and cut using a pelletizer to produce an acrylic resin composition.

[0071] [Masterbatch]

[0072] The first embodiment of the masterbatch of this embodiment comprises an acrylic resin and acrylic crosslinked particles having an average particle size of 1 μm or less, with the acrylic crosslinked particles containing 5% by weight or more. Furthermore, the second embodiment of the masterbatch of this embodiment comprises an acrylic resin having a glass transition temperature of 120°C or higher and acrylic crosslinked particles, with the acrylic crosslinked particles containing 5% by weight or more. The masterbatch of this embodiment is manufactured using the masterbatch manufacturing method of this embodiment.

[0073] The number of particles with a particle size of 10 μm or greater per 1 mg of the masterbatch of this embodiment, measured by dissolving or dispersing the masterbatch in dichloromethane to a solid content concentration of 40 ppm by weight, is, for example, 200 or fewer, preferably 180 or fewer, and more preferably 160 or fewer. When the number of particles with a particle size of 10 μm or greater per 1 mg of the masterbatch of this embodiment, measured by dissolving or dispersing the masterbatch in dichloromethane to a solid content concentration of 40 ppm by weight, is 200 or fewer, the masterbatch of this embodiment has few poorly dispersed particles. Therefore, even if the masterbatch is added to produce the acrylic resin composition for a long period of time, the pressure difference between the outlet and inlet of the polymer filter provided on the upstream side of the die of the extruder is unlikely to increase.

[0074] The masterbatch of this embodiment, when dissolved or dispersed in dichloromethane to a solids concentration of 40 ppm by weight, shows a particle size of 10 μm to 20 μm per 1 mg of masterbatch, which is measured to be, for example, 120 or fewer. Consequently, the masterbatch of this embodiment contains fewer poorly dispersed particles. Therefore, even when the masterbatch is added to produce acrylic resin compositions for extended periods, the pressure differential between the outlet and inlet of the polymer filter located upstream of the extruder die is unlikely to increase.

[0075] [Method for producing optical film]

[0076] The optical film can be produced by a known method using the acrylic resin composition of the present embodiment. An example of a method for producing the optical film will be described below.

[0077] First, the acrylic resin composition of this embodiment is fed from the main feeder of a twin-screw extruder and melted. Next, a sheet is extruded from the T-die of the twin-screw extruder and then cooled using chill rolls to produce an acrylic film. The acrylic film is then biaxially stretched to produce an optical film. The biaxial stretching can be simultaneous or sequential.

[0078] As for the temperature for biaxially stretching the acrylic film, when the glass transition temperature of the acrylic resin is set to Tg, it is preferably above (Tg+5)°C and below (Tg+30)°C, more preferably above (Tg+6)°C and below (Tg+25)°C, and further preferably above (Tg+7)°C and below (Tg+20)°C. In addition, the surface ratio when biaxially stretching the acrylic film is not particularly limited, for example, it is above 2 times and below 10 times. The stretching speed when biaxially stretching the acrylic film is not particularly limited, for example, it is above 1.1 times / minute and below 100 times / minute. When the acrylic film is subjected to sequential biaxial stretching, the stretching speed of the first section and the stretching speed of the second section may be the same or different. It should be noted that in sequential biaxial stretching, usually, the stretching of the first section is stretching in the longitudinal direction (MD direction), and the stretching of the second section is stretching in the width direction (TD direction).

[0079] Examples of the optical film include a polarizer protective film and a retardation film.

[0080] As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment, and the said embodiment can be modified suitably within the range of the summary of this invention.

[0081] [Example]

[0082] Hereinafter, the present invention will be described in more detail based on Examples and Comparative Examples. Although Examples of the present invention will be described, the present invention is not limited to the Examples.

[0083] [Examples 1 to 11, Comparative Examples 1 to 5]

[0084] (Manufacture of acrylic resin)

[0085] An intermeshing, co-rotating twin-screw extruder (L / D = 90) with a diameter of 40 mm was used to produce acrylic resin (I). Here, L and D are the length and diameter of the extruder, respectively. At this time, the barrel temperature was set to 250-280°C, and the screw speed was set to 85 rpm. Next, a loss-in-weight feeder CE-T-2E (manufactured by KUBOTA Corporation) was used to feed polymethyl methacrylate resin (Mw = 105,000) to the main feeder at a feed rate of 42.4 kg / h. After the resin was melted and filled with a kneading block, 1.8% by weight of monomethylamine (manufactured by Mitsubishi Gas Chemical) was injected into the resin from the nozzle. At this time, a reverse-flight was inserted at the end of the reaction zone to fill the resin. In addition, the pressure at the exhaust port was reduced to -0.092 MPa to remove the by-products and excess monomethylamine after the reaction. Next, the strands discharged from the die of the extruder were cooled in a water tank and then cut with a pelletizer to obtain pelletized acrylic resin (I).

[0086] An intermeshing, co-rotating twin-screw extruder (L / D=90) with a diameter of 40 mm was used to produce acrylic resin (A1). At this time, the barrel temperature was set to 240-260°C and the screw speed was set to 102 rpm. Next, using a loss-in-weight feeder CE-T-2E (manufactured by KUBOTA Corporation), acrylic resin (I) was supplied to the main feeder at a supply rate of 41 kg / hr. After the resin was melted and filled with a kneading block, 0.56% by weight of dimethyl carbonate was injected into the resin from the nozzle to reduce the carboxyl groups in the resin. At this time, a reverse screw thread was inserted at the end of the reaction zone to fill the resin. In addition, the pressure at the exhaust port was reduced to -0.092 MPa to remove the by-products and excess dimethyl carbonate after the reaction. Next, the strands discharged from the die of the extruder were cooled in a water tank and cut with a granulator to obtain granular acrylic resin (A1). The acrylic resin (A1) has a glutarimide ring in the main chain, the content of the structural unit having the glutarimide ring is 6% by weight, the glass transition temperature is 125° C., and the average refractive index is 1.50.

[0087] (Manufacturing of Masterbatch)

[0088] A masterbatch was produced using a 40 mm diameter intermeshing twin-screw extruder (L / D=90). As the raw resin composition, a mixture of 85 parts by weight of acrylic resin (A1), 9 parts by weight of acrylic crosslinked particles with an average particle size of 0.8 μm, 4 parts by weight of crosslinked acrylic particles with an average particle size of 0.15 μm, and a prescribed amount of additives (see Table 1) was used. At this time, the barrel temperature and the screw speed were set to prescribed values (see Table 1). Next, a loss-in-weight feeder CE-T-2E (manufactured by KUBOTA Corporation) was used to feed the raw resin composition to the main feeder at a prescribed feed rate (see Table 1), and the resin was melted using a kneading block. Next, the strands discharged from the die of the extruder were cooled in a water tank and then cut with a pelletizer to obtain a pelletized masterbatch.

[0089] Table 1 shows the production conditions of the masterbatch.

[0090] [Table 1]

[0091]

[0092] Here, additives A1 to A3 are as follows.

[0093] A1: Lubricant with a melting point of 101°C; stearamide

[0094] A2: Lubricant with a melting point of 100°C; palmitic acid amide

[0095] A3: UV absorber with a melting point of 144 to 150°C; 2,4,6-tris(2-hydroxy-4-hexyloxy-3-methylphenyl)-1,3,5-triazine; ADEKA STAB LA-F70 (manufactured by ADEKA)

[0096] (Number of particles)

[0097] 0.6 g of the masterbatch was dissolved or dispersed in 20 g of dichloromethane to obtain a masterbatch dispersion. Then, 0.22 g of the masterbatch dispersion was diluted with 160 g of dichloromethane to obtain a dilute masterbatch solution having a solids concentration of 40 ppm by weight. It should be noted that the dichloromethane used was filtered through a membrane filter with a mesh size of 0.22 μm. Next, the number of particles in 20 ml of the dilute masterbatch solution was measured using a liquid particle counter KS-42D (manufactured by RION).

[0098] (Poorly dispersed particles)

[0099] The dilute solution used for the particle count measurement was filtered through a membrane filter with a mesh size of 2 μm, and the collected matter on the membrane filter was observed using a SEM to evaluate the dispersibility.

[0100] 1: There are 5 or more poorly dispersed particles in the field of view

[0101] 2: There are 2 or more but less than 5 poorly dispersed particles in the field of view

[0102] 3: There are 0 or more but less than 2 poorly dispersed particles in the field of view

[0103] (Production of Acrylic Resin Composition)

[0104] An acrylic resin composition was produced using a tandem extruder reactor consisting of a first extruder and a second extruder connected in series. Both the first and second extruders were 75 mm diameter, intermeshing, co-rotating twin-screw extruders (L / D = 74). The die of the first extruder and the main feeder of the second extruder were connected by a 38 mm diameter, 2 m long pipe. A constant flow pressure valve was used as a pressure control mechanism within the pipe.

[0105] A loss-in-weight feeder CE-T-2E (manufactured by KUBOTA Corporation) was used to supply the raw resin to the main feeder of the first extruder. The pressure at each vent in the first and second extruders was reduced to -0.095 MPa. Polymethyl methacrylate resin (Mw = 105,000) was used as the raw resin, and monomethylamine was used as the imidizing agent to produce acrylic resin 1. At this time, the set temperature of the highest temperature section of the barrel of the first extruder was set to 280°C, the screw speed was set to 55 rpm, the feed rate of the raw resin was set to 150 kg / h, and the amount of monomethylamine added was set to 2.0% by weight relative to the raw resin. In addition, a constant flow pressure valve was installed just before the main feeder of the second extruder, and the pressure of the monomethylamine injection section of the first extruder was adjusted to 8 MPa. The strands discharged from the die of the second extruder were cooled using a cooling conveyor and then cut using a pelletizer to produce pelletized acrylic resin compositions. Here, in order to adjust the pressure in the pipe connecting the die of the first extruder and the main feeder of the second extruder or to clearly observe extrusion fluctuations, resin pressure gauges are installed in the die of the first extruder, the center of the pipe, and the die of the second extruder.

[0106] After devolatilization of the remaining imidization reaction reagent and by-products at the rear exhaust port and vacuum exhaust port of the second extruder, a mixed solution of dimethyl carbonate and triethylamine as an esterifying agent was added to produce acrylic resin 2. At this time, the set temperature of each barrel of the second extruder was set to 260°C, and the screw speed was set to 55 rpm. In addition, the amount of dimethyl carbonate added was set to 3.2% by weight relative to the raw resin. In addition, the amount of triethylamine added was set to 0.8% by weight relative to the raw resin. Furthermore, after the esterifying agent was removed at the exhaust port, a masterbatch was added from the side feeder at a rate of 1% by weight relative to the raw resin. Thereafter, the strands were filtered through a blade disc type polymer filter (filtration accuracy 5 μm) by means of a gear pump and discharged from the die. After cooling in a water tank, they were cut with a granulator to obtain a pelletized acrylic resin composition.

[0107] (Pressure differential rise)

[0108] Twelve hours after the acrylic resin composition was produced, the differential pressure between the outlet and inlet of the polymer filter was measured to evaluate the differential pressure increase.

[0109] 1: When the pressure difference rises to 0.3 MPa or more

[0110] 2: When the pressure difference rises below 0.3 MPa

[0111] Table 2 shows the evaluation results of poorly dispersed particles in the masterbatch and the pressure differential increase during the production of the acrylic resin composition. Here, PC (≥10 μm) and PC (10-20 μm) refer to the number of particles with a particle size of 10 μm or greater per 1 mg of masterbatch and the number of particles with a particle size of 10 μm or greater and 20 μm or less per 1 mg of masterbatch, respectively.

[0112] [Table 2]

[0113]

[0114] As shown in Table 2, in Examples 1 to 11, the number of poorly dispersed particles in the masterbatch was small, and the pressure difference increase during the production of the acrylic resin composition was small. In contrast, in Comparative Examples 1 to 4, the barrel temperature was 210 to 250°C, so the number of poorly dispersed particles in the masterbatch was large, and the pressure difference increase during the production of the acrylic resin composition was large. In particular, in Comparative Example 1, Q / N / (D / 40) 3 =0.268 [kg / h / rpm], so there are many poorly dispersed particles in the masterbatch. In addition, in Comparative Example 5, Q / N / (D / 40) 3 Since the speed was 0.133 [kg / h / rpm], there were many poorly dispersed particles in the masterbatch, and the pressure difference during the production of the acrylic resin composition increased significantly.

Claims

1. A method for producing a masterbatch, comprising supplying a raw material resin composition to an extruder equipped with a barrel and a screw to produce a masterbatch. The temperature of the barrel is below 200°C, The manufacturing method satisfies the following formula (1): The raw resin composition comprises an acrylic resin and acrylic crosslinked particles having an average particle size of 1 μm or less, wherein the content of the acrylic crosslinked particles is 5% by weight or more. Q / N / (D / 40) 3 ≤0.11···(1) Wherein, Q is the feed rate of the raw resin composition [kg / h], N is the rotation speed of the screw [rpm], and D is the diameter of the extruder [mm].

2. The method for producing a masterbatch according to claim 1, wherein: The raw resin composition further includes an additive having a melting point of 200° C. or lower.

3. The method for producing a masterbatch according to claim 2, wherein: The additive is a lubricant or an ultraviolet absorber.

4. The method for producing a masterbatch according to any one of claims 1 to 3, wherein The acrylic resin has a glass transition temperature of 120° C. or higher.

5. The method for producing a masterbatch according to claim 4, wherein: The acrylic resin has a ring structure in the main chain.

6. A method for producing an acrylic resin composition, comprising: A step of obtaining a masterbatch by the method for producing a masterbatch according to any one of claims 1 to 3, and a step of mixing the masterbatch with an acrylic resin having a ring structure in its main chain.

7. A masterbatch comprising an acrylic resin and acrylic crosslinked particles having an average particle size of 1 μm or less, wherein the content of the acrylic crosslinked particles is 5% by weight or more. The masterbatch was dissolved or dispersed in dichloromethane so as to have a solid content concentration of 40 ppm by weight, and the number of particles having a particle size of 10 μm or greater per 1 mg of the masterbatch was measured to be 200 or less.

8. A masterbatch comprising an acrylic resin having a glass transition temperature of 120° C. or higher and acrylic crosslinked particles, wherein the content of the acrylic crosslinked particles is 5% by weight or higher. The masterbatch was dissolved or dispersed in dichloromethane so as to have a solid content concentration of 40 ppm by weight, and the number of particles having a particle size of 10 μm or greater per 1 mg of the masterbatch was measured to be 200 or less.

9. The masterbatch according to claim 7 or 8, wherein The masterbatch was dissolved or dispersed in dichloromethane so as to have a solid content concentration of 40 ppm by weight, and the number of particles having a particle size of 10 μm or more and 20 μm or less per 1 mg of the masterbatch was measured to be 120 or less.

10. A masterbatch comprising an acrylic resin and acrylic crosslinked particles having an average particle size of 1 μm or less, wherein the content of the acrylic crosslinked particles is 5% by weight or more. The masterbatch was dissolved or dispersed in dichloromethane so as to have a solid content concentration of 40 ppm by weight, and the number of particles having a particle size of 10 μm or more and 20 μm or less per 1 mg of the masterbatch was measured to be 120 or less.

11. A masterbatch comprising an acrylic resin having a glass transition temperature of 120° C. or higher and acrylic crosslinked particles, wherein the content of the acrylic crosslinked particles is 5% by weight or higher. The masterbatch was dissolved or dispersed in dichloromethane so as to have a solid content concentration of 40 ppm by weight, and the number of particles having a particle size of 10 μm or more and 20 μm or less per 1 mg of the masterbatch was measured to be 120 or less.

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