WO2009090900A1

WO2009090900A1 - Acrylic resin-containing film and process for the production of the film

Info

Publication number: WO2009090900A1
Application number: PCT/JP2009/050059
Authority: WO
Inventors: Takashi Takebe; Masataka Takimoto; Nobuo Kubo
Original assignee: Konica Minolta Opto, Inc.
Priority date: 2008-01-18
Filing date: 2009-01-07
Publication date: 2009-07-23
Also published as: KR20100103584A; JPWO2009090900A1; KR101497751B1

Abstract

The invention provides an acrylic resin-containing film which is transparent and which exhibits high heat resistant and is remarkably improved in brittleness, and a process for the production of the film. An acrylic resin-containing film which contains an acrylic resin as the main constituent component, characterized in that the film contains an acrylic resin and a cellulose ester resin at a mass ratio of 95:5 to 30:70, that the cellulose ester resin has a total degree of substitution with acyl of 2.00 to 2.99 and a degree of substitution with acetyl of 0.10 to 1.89, and the substituent acyl groups thereof other than acetyl each have 3 to 7 carbon atoms, that the cellulose ester resin has a weight -average molecular weight of 75000 to 280000, and that the film exhibits a haze of less than 1% and a tension softening point of 105 to 145°C and dose not cause ductile fracture.

Description

Acrylic resin-containing film and method for producing the same

The present invention relates to an acrylic resin-containing film that is transparent, has high heat resistance, and remarkably improves brittleness, and a method for producing the same.

Polymethyl methacrylate (hereinafter abbreviated as “PMMA”), which is a representative of conventional acrylic resins, is suitably used for optical films from the viewpoint of its excellent transparency, dimensional stability, low hygroscopicity, and the like. It was.

However, the PMMA film has poor heat resistance and has a problem that its shape changes when used at high temperatures or for long-term use.

This problem was an important issue not only as a physical property of a single film but also in a polarizing plate and a display device using such a film. That is, in the liquid crystal display device, because the polarizing plate curls with the deformation of the film, the entire panel is warped, and the design phase difference changes even when used at the position on the viewing side surface. There was a problem that the viewing angle fluctuated and the color changed.

In order to improve heat resistance, a method of adding polycarbonate to an acrylic resin has been proposed, but since there is a limit to the solvent that can be used and the compatibility between the resins is insufficient, it tends to become cloudy and as an optical film Use was difficult (for example, refer patent document 1).

On the other hand, when an acrylic resin is industrially produced by a solution casting film forming method, it is generally cast on a metal base material such as a steel belt as a support, and a film-like material called a web is formed. A method is generally known in which the solvent contained in the web is volatilized to some extent and then peeled off from the support.

However, in the state containing the solvent, the acrylic resin has high adhesiveness to the metal, and the film may be excessively stretched or broken at the time of peeling. Further, when the solvent is sufficiently volatilized, the productivity is deteriorated, and a large charge is generated at the time of peeling, so that the flatness and appearance of the film may be impaired. In order to solve this, Patent Document 2 discloses the addition of a release agent, coating treatment on the metal belt surface, etc., but the former may cause the release agent to bleed and impair the appearance, while the latter is produced. There was a problem that the performance decreased.
JP-A-5-306344 JP 2007-176982 A

The present invention has been made in view of the above-mentioned problems and situations, and a solution to that problem is to provide an acrylic resin-containing film that is transparent, has high heat resistance, and has markedly improved brittleness, and a method for producing the same. .

The above-mentioned problem according to the present invention is solved by the following means.

1. An acrylic resin-containing film containing an acrylic resin as a main constituent, containing an acrylic resin and a cellulose ester resin in a mass ratio of 95: 5 to 30:70, and having a total substitution degree of acyl groups of the cellulose ester resin 2.00 to 2.99, acetyl group substitution degree is 0.10 to 1.89, carbon number of acyl group other than acetyl group is 3 to 7, and weight average molecular weight is 75000 to 280000, An acrylic resin-containing film, wherein the resin-containing film has a haze of less than 1%, a tension softening point of 105 to 145 ° C., and does not cause ductile fracture.

2. 2. The acrylic resin-containing film according to 1 above, containing 0.05 to 45 parts by mass of acrylic fine particles with respect to 100 parts by mass of the total mass of the acrylic resin and the cellulose ester resin.

3. 3. The method for producing an acrylic resin-containing film as described in 1 or 2 above, which comprises a step of casting the dope composition on an endless belt and then peeling the film, wherein the dope composition is methylene chloride and a linear chain having 1 to 4 carbon atoms. Or a dope composition having a solid content of 15 to 45% by mass containing a branched aliphatic alcohol, an acrylic resin, and a cellulose ester resin, and a ratio of the methylene chloride to the aliphatic alcohol (in the formula (i) below) MA) is 4 to 20, and 30 to 240 seconds after casting the dope composition on an endless belt, the residual solvent concentration represented by the following formula (ii) is 50 to 120%. A method for producing an acrylic resin-containing film, characterized by peeling.
Formula (i): MA = mass of aliphatic alcohol / (mass of aliphatic alcohol + mass of methylene chloride) × 100
Formula (ii): Residual solvent concentration (%) = (mass of cast film−mass of dry film) / mass of dry film × 100 (%)

By the above means of the present invention, it is possible to provide an acrylic resin-containing film that is transparent, has high heat resistance, and has markedly improved brittleness, and a method for producing the same.

In addition, the acrylic resin containing film of this invention can be used suitably for a polarizing plate. Accordingly, it is possible to provide a liquid crystal display device that can improve the yield in operations such as punching of polarizing plates and panel bonding, and can maintain good visibility even in long-term use.

Schematic diagram showing the dope preparation process, casting process and drying process of the solution casting film forming method

Explanation of symbols

DESCRIPTION OF SYMBOLS 1

Melting pot

3, 6, 12, 15 Filter 4, 13 Stock tank 5, 14

Liquid feed pump

8, 16 Conduit 10 Ultraviolet absorber charging pot 20 Merge pipe 21 Mixer 30 Die 31 Metal support 32 Web 33 Peeling position 34 Tenter device 35 Roll dryer 41 Particle charging vessel 42 Stock tank 43 Pump 44 Filter

Hereinafter, the present invention, its constituent elements, and the best mode and mode for carrying out the present invention will be described in detail.

(Acrylic resin-containing film)
The acrylic resin-containing film of the present invention is an acrylic resin-containing film containing an acrylic resin as a main constituent, and contains the acrylic resin and the cellulose ester resin in a mass ratio of 95: 5 to 30:70, and the cellulose ester The total substitution degree of the acyl group of the resin is 2.00 to 2.99, the substitution degree of the acetyl group is 0.10 to 1.89, the number of carbons of the acyl group other than the acetyl group is 3 to 7, and the weight average molecular weight is The acrylic resin-containing film has a haze of less than 1%, a tension softening point of 105 to 145 ° C., and no ductile fracture. This feature is a technical feature common to the inventions according to claims 1 to 3.

As an embodiment of the present invention, 0.05 to 45 parts by mass of acrylic fine particles are preferably contained with respect to 100 parts by mass of the total mass of the acrylic resin and the cellulose ester resin.

In the present application, the “ductile fracture” is caused by a stress that is greater than the strength of a certain material, and is defined as a fracture accompanied by significant elongation or squeezing of the material until the final fracture. The fracture surface is characterized by numerous indentations called dimples.

Therefore, “an acrylic resin-containing film that does not cause ductile fracture” is characterized in that fracture such as fracture is not observed even when a large stress is applied to bend the film in two.

The demand for the brittleness of optical films is increasing from the viewpoint of reworkability and productivity as optical films become larger and thinner with the recent increase in liquid crystal display devices, and the above ductile fracture does not occur. Is required.

Forming an acrylic resin-containing film that does not cause ductile fracture is achieved by appropriately selecting the material configuration of the acrylic resin, cellulose ester, and other additives used.

The acrylic resin-containing film of the present invention has a tension softening point of 105 when considering use in a high-temperature environment such as a device having a high haze and a high temperature such as a projector or a vehicle-mounted display device. The temperature is preferably ˜145 ° C., more preferably 110 to 140 ° C.

As a specific method for measuring the tension softening point temperature of an acrylic resin-containing film, for example, using a Tensilon tester (ORIENTEC Co., RTC-1225A), the acrylic resin-containing film is 120 mm (length) × 10 mm (width). The temperature is increased at a rate of temperature increase of 30 ° C./min while pulling at a tension of 10 N, and the temperature at the time of 9 N is measured three times, and the average value can be obtained.

The acrylic resin-containing film of the present invention preferably has a glass transition temperature (Tg) of 110 ° C. or higher. More preferably, it is 120 ° C. or higher. Especially preferably, it is 150 degreeC or more.

The glass transition temperature referred to here is an intermediate value determined according to JIS K7121 (1987) using a differential scanning calorimeter (DSC-7 model manufactured by Perkin Elmer) at a heating rate of 20 ° C./min. Point glass transition temperature (Tmg).

The acrylic resin-containing film of the present invention has a defect of 5 μm or more in diameter in the film plane of 1 piece / 10 cm square. More preferably, it is 0.5 piece / 10 cm square or less, more preferably 0.1 piece / 10 cm square or less.

Here, the diameter of the defect indicates the diameter when the defect is circular, and when it is not circular, the range of the defect is determined by observing with a microscope according to the following method, and the maximum diameter (diameter of circumscribed circle) is determined.

The range of the defect is the size of the shadow when the defect is observed with the transmitted light of the differential interference microscope when the defect is a bubble or a foreign object. When the defect is a change in the surface shape, such as transfer of a roll flaw or an abrasion, the size is confirmed by observing the defect with the reflected light of a differential interference microscope.

In addition, when observing with reflected light, if the size of the defect is not clear, aluminum or platinum is vapor-deposited on the surface for observation.

In order to obtain a film having excellent quality expressed by such a defect frequency with high productivity, it is necessary to filter the polymer solution with high precision immediately before casting, to increase the cleanliness around the casting machine, It is effective to set drying conditions after rolling stepwise and to dry efficiently while suppressing foaming.

When the number of defects is more than 1/10 cm square, for example, when a tension is applied to the film during processing in a later process, the film breaks with the defect as a starting point, and the productivity may be significantly reduced. Moreover, when the diameter of a defect becomes 5 micrometers or more, it can confirm visually by polarizing plate observation etc., and when used as an optical member, a bright spot may arise.

In addition, even when it cannot be visually confirmed, when a hard coat layer or the like is formed on the film, the coating agent may not be formed uniformly, which may result in a defect (missing coating). Here, the defect is a void in the film (foaming defect) generated due to the rapid evaporation of the solvent in the drying process of the solution casting, a foreign matter in the film forming stock solution, or a foreign matter mixed in the film forming. This refers to the foreign matter (foreign matter defect) in the film.

The acrylic resin-containing film of the present invention preferably has a breaking elongation in at least one direction of 10% or more, more preferably 20% or more, as measured in accordance with JIS-K7127-1999.

The upper limit of the elongation at break is not particularly limited, but is practically about 250%. In order to increase the elongation at break, it is effective to suppress defects in the film caused by foreign matter and foaming.

The thickness of the acrylic resin-containing film of the present invention is preferably 20 μm or more. More preferably, it is 30 μm or more.

The upper limit of the thickness is not particularly limited, but in the case of forming a film by a solution casting method, the upper limit is about 250 μm from the viewpoints of applicability, foaming, solvent drying, and the like. In addition, the thickness of a film can be suitably selected according to a use.

The acrylic resin-containing film of the present invention preferably has a total light transmittance of 90% or more, more preferably 93% or more. The practical upper limit is about 99%. In order to achieve excellent transparency expressed by such total light transmittance, it is necessary not to introduce additives and copolymerization components that absorb visible light, or to remove foreign substances in the polymer by high-precision filtration. It is effective to reduce the diffusion and absorption of light inside the film.

Also, reduce the surface roughness of the film surface by reducing the surface roughness of the film contact part (cooling roll, calender roll, drum, belt, coating substrate in solution casting, transport roll, etc.) during film formation. It is also effective to reduce the diffusion and reflection of light on the film surface by reducing the refractive index of the acrylic resin.

The acrylic resin-containing film of the present invention is characterized in that the haze value (turbidity), which is one of the indices indicating transparency, is 1.0% or less, but the luminance when incorporated in a liquid crystal display device, From the viewpoint of contrast, it is preferably 0.5% or less.

In order to achieve such a haze value, it is effective to remove foreign substances in the polymer by high-precision filtration and reduce the diffusion of light inside the film.

When using acrylic particles, it is also effective to reduce the difference in refractive index between the acrylic resin and the acrylic particles.

In addition, since the surface roughness also affects the haze value as surface haze, it is also effective to reduce the particle size and addition amount of acrylic particles within the above range, or to reduce the surface roughness of the film contact portion during film formation It is.

The total light transmittance and haze value of the acrylic resin-containing film are values measured according to JIS-K7361-1-1997 and JIS-K7136-2000.

The acrylic resin-containing film of the present invention can be preferably used as an optical acrylic resin-containing film as long as it satisfies the physical properties as described above, but is excellent in workability and heat resistance by having the following composition. Film can be obtained.

That is, from the viewpoint of achieving both workability and heat resistance, the acrylic resin-containing film contains acrylic resin and cellulose ester resin in a mass ratio of 95: 5 to 30:70, and the total acyl groups of the cellulose ester resin are the same. The degree of substitution (T) is 2.00 to 2.99, the degree of acetyl group substitution (ac) is 0.10 to 1.89, the number of carbons of the acyl group other than the acetyl group is 3 to 7, and the weight average molecular weight ( The excellent effect of the present invention can be obtained by the acrylic resin-containing film characterized in that Mw) is 75000 to 280000.

In the acrylic resin-containing film of the present invention, the acrylic resin and the cellulose ester resin are contained in a mass ratio of 95: 5 to 30:70, but the acrylic resin is preferably 50% by mass or more.

The acrylic resin-containing film of the present invention may contain a resin other than acrylic resin and cellulose ester resin.

The total mass of the acrylic resin and the cellulose ester resin is 55 to 100% by mass, preferably 60 to 99% by mass of the acrylic resin-containing film.

The method for producing an acrylic resin-containing film of the present invention is a method for producing an acrylic resin-containing film having a step of peeling a dope composition onto an endless belt and then peeling off, wherein the dope composition contains methylene chloride and carbon number. A dope composition having a solid content of 15 to 45% by mass containing 1 to 4 linear or branched aliphatic alcohol, acrylic resin, and cellulose ester resin, wherein the ratio of methylene chloride to aliphatic alcohol ( MA) represented by the following formula (ii) is 4 to 20, and 30 to 240 seconds after casting the dope composition onto an endless belt, the residual solvent concentration represented by the following formula (i) is 50 It is preferable that the method for producing an acrylic resin-containing film is characterized in that the film is peeled off in a state of ˜120%.
Formula (i): MA = mass of aliphatic alcohol / (mass of aliphatic alcohol + mass of methylene chloride) × 100
Formula (ii): Residual solvent concentration (%) = (mass of cast film−mass of dry film) / mass of dry film × 100 (%)
In the production method, it is preferable that 0.5 to 45 parts by mass of acrylic fine particles are contained with respect to 100 parts by mass of the total mass of the acrylic resin and the cellulose ester resin.

Hereinafter, the components of the present invention will be described in detail.

<acrylic resin>
The acrylic resin used in the present invention includes a methacrylic resin. The resin is not particularly limited, but a resin comprising 50 to 99% by mass of methyl methacrylate units and 1 to 50% by mass of other monomer units copolymerizable therewith is preferable.

Examples of other copolymerizable monomers include alkyl methacrylates having 2 to 18 alkyl carbon atoms, alkyl acrylates having 1 to 18 carbon atoms, alkyl acrylates such as acrylic acid and methacrylic acid. Saturated acids, maleic acids, fumaric acids, divalent carboxylic acids containing unsaturated groups such as itaconic acid, aromatic vinyl compounds such as styrene, α-methylstyrene, and nucleus-substituted styrene, α, β- such as acrylonitrile, methacrylonitrile, etc. Examples thereof include unsaturated nitrile, maleic anhydride, maleimide, N-substituted maleimide, and glutaric anhydride, and these can be used alone or in combination of two or more.

Among these, methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, s-butyl acrylate, 2-ethylhexyl acrylate, and the like are preferable from the viewpoint of thermal decomposition resistance and fluidity of the copolymer. n-Butyl acrylate is particularly preferably used.

The acrylic resin used in the acrylic resin-containing film of the present invention preferably has a weight average molecular weight (Mw) of 80,000 to 1,000,000 from the viewpoint of mechanical strength as a film and fluidity when producing the film.

The weight average molecular weight of a resin such as an acrylic resin according to the present invention can be measured by gel permeation chromatography. The measurement conditions are as follows.

Solvent: Methylene chloride Column: Shodex K806, K805, K803G (Used by connecting three Showa Denko Co., Ltd.)
Column temperature: 25 ° C
Sample concentration: 0.1% by mass
Detector: RI Model 504 (manufactured by GL Sciences)
Pump: L6000 (manufactured by Hitachi, Ltd.)
Flow rate: 1.0ml / min
Calibration curve: Standard polystyrene STK standard polystyrene (manufactured by Tosoh Corp.) Mw = 2,800,000-500 calibration curves with 13 samples were used. The 13 samples are preferably used at approximately equal intervals.

The production method of the acrylic resin in the present invention is not particularly limited, and any known method such as suspension polymerization, emulsion polymerization, bulk polymerization, or solution polymerization may be used. Here, as a polymerization initiator, a normal peroxide type and an azo type can be used, and a redox type can also be used. The polymerization temperature may be 30 to 100 ° C. for suspension or emulsion polymerization, and 80 to 160 ° C. for bulk or solution polymerization. Furthermore, in order to control the reduced viscosity of the produced copolymer, polymerization can be carried out using alkyl mercaptan or the like as a chain transfer agent.

By using this molecular weight, both heat resistance and brittleness can be achieved.

Commercially available acrylic resins can be used as the acrylic resin of the present invention. For example, Delpet 60N, 80N (Asahi Kasei Chemicals Co., Ltd.), Dialal BR52, BR80, BR83, BR85, BR88 (Mitsubishi Rayon Co., Ltd.), KT75 (Electrochemical Industry Co., Ltd.) and the like can be mentioned. .

<Cellulose ester resin>
The cellulose ester resin used in the present invention may be substituted with either an aliphatic acyl group or an aromatic acyl group, but is preferably substituted with an acetyl group.

When the cellulose ester resin of the present invention is an ester with an aliphatic acyl group, the aliphatic acyl group has 2 to 20 carbon atoms, specifically acetyl, propionyl, butyryl, isobutyryl, valeryl, pivaloyl, hexanoyl, Examples include octanoyl, lauroyl, stearoyl and the like.

In the present invention, the aliphatic acyl group is meant to include those further having a substituent. When the aromatic ring is a benzene ring in the above-described aromatic acyl group, the substituent of the benzene ring Are exemplified.

When the cellulose ester resin is an ester with an aromatic acyl group, the number of substituents X substituted on the aromatic ring is 0 or 1 to 5, preferably 1 to 3, and particularly preferably One or two.

Further, when the number of substituents substituted on the aromatic ring is 2 or more, they may be the same or different from each other, but they may be linked together to form a condensed polycyclic compound (for example, naphthalene, indene, indane, phenanthrene, quinoline). , Isoquinoline, chromene, chroman, phthalazine, acridine, indole, indoline, etc.).

As the structure used in the cellulose resin of the present invention, the cellulose ester resin has a structure having a structure selected from at least one of a substituted or unsubstituted aliphatic acyl group and a substituted or unsubstituted aromatic acyl group. Used, these may be single or mixed acid esters of cellulose.

The substitution degree of the cellulose ester resin according to the present invention is such that the total substitution degree (T) of the acyl group is 2.00 to 2.99, and the substitution degree (ac) of the acetyl group is 0.10 to 1.89. More preferably, the acyl group substitution degree (r) other than the acetyl group is 2.00 to 2.89. The acyl group other than the acetyl group preferably has 3 to 7 carbon atoms.

In the cellulose ester resin of the present invention, those having an acyl group having 2 to 7 carbon atoms as a substituent, that is, cellulose acetate, cellulose propionate, cellulose butyrate, cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate It is preferably at least one selected from benzoate and cellulose benzoate.

Among these, particularly preferable cellulose ester resins include cellulose acetate, cellulose propionate, cellulose butyrate, cellulose acetate propionate, and cellulose acetate butyrate.

More preferably, the mixed fatty acid is a lower fatty acid ester of cellulose acetate propionate or cellulose acetate butyrate having an acyl group having 2 to 4 carbon atoms as a substituent.

The portion not substituted with an acyl group usually exists as a hydroxyl group. These can be synthesized by known methods.

Incidentally, the substitution degree of the acetyl group and the substitution degree of other acyl groups were determined by the method prescribed in ASTM-D817-96.

If the weight average molecular weight (Mw) of the cellulose ester resin of the present invention is 75000 or more, the object of the present invention can be achieved even if the weight average molecular weight is about 1000000, but considering productivity, it is 75000 to 280000. Those of 100,000 to 240,000 are more preferred.

<Acrylic particles>
In the present invention, the acrylic resin-containing film may contain acrylic particles.

The acrylic particles according to the present invention are characterized by being present in the state of particles in the acrylic resin, cellulose ester resin and acrylic resin-containing film (also referred to as incompatible state).

The acrylic particles are obtained by, for example, collecting a predetermined amount of the prepared acrylic resin-containing film, dissolving in a solvent, stirring, and sufficiently dissolving and dispersing the PTFE film having a pore diameter less than the average particle diameter of the acrylic particles. It is preferable that the weight of the insoluble matter filtered and collected using the membrane filter is 90% by mass or more of the acrylic particles added to the acrylic resin-containing film.

The acrylic particles used in the present invention are not particularly limited, but are preferably acrylic particles having a layer structure of two or more layers, and particularly preferably the following multilayer structure acrylic granular composite.

The multilayer structure acrylic granular composite is formed by laminating an innermost hard layer polymer, a cross-linked soft layer polymer exhibiting rubber elasticity, and an outermost hard layer polymer from the center to the outer periphery. This refers to a particulate acrylic polymer having a structure.

Preferred embodiments of the multilayer structure acrylic granular composite used in the acrylic resin composition of the present invention include the following. (A) Monomer comprising 80 to 98.9% by weight of methyl methacrylate, 1 to 20% by weight of alkyl acrylate having 1 to 8 carbon atoms in the alkyl group, and 0.01 to 0.3% by weight of polyfunctional grafting agent (B) 75 to 98.5% by mass of an alkyl acrylate having 4 to 8 carbon atoms in the presence of the innermost hard layer polymer in the presence of the innermost hard layer polymer, A crosslinked soft layer polymer obtained by polymerizing a monomer mixture comprising 0.01 to 5% by mass of a multifunctional crosslinking agent and 0.5 to 5% by mass of a multifunctional grafting agent; (c) the innermost hard In the presence of a polymer comprising a layer and a crosslinked soft layer, a monomer mixture comprising 80 to 99% by mass of methyl methacrylate and 1 to 20% by mass of alkyl acrylate having 1 to 8 carbon atoms in the alkyl group is polymerized. Outermost hard layer weight And the obtained three-layer structure polymer is an innermost hard layer polymer (a) 5 to 40% by mass, a soft layer polymer (b) 30 to 60% by mass, and An outermost hard layer polymer (c) comprising 20 to 50% by mass, having an insoluble part when fractionated with acetone, and an acrylic granular composite having a methyl ethyl ketone swelling degree of 1.5 to 4.0 at the insoluble part .

As disclosed in Japanese Patent Publication No. 60-17406 or Japanese Patent Publication No. 3-39095, not only the composition and particle size of each layer of the multilayer structure acrylic granular composite are defined, but also the multilayer structure acrylic particulate. By setting the tensile elastic modulus of the composite and the degree of swelling of methyl ethyl ketone in the acetone-insoluble part within a specific range, it becomes possible to realize a further sufficient balance between impact resistance and stress whitening resistance.

Here, the innermost hard layer polymer (a) constituting the multilayer structure acrylic granular composite is 80 to 98.9% by mass of methyl methacrylate and 1 to 20 mass of alkyl acrylate having 1 to 8 carbon atoms in the alkyl group. % And a monomer mixture consisting of 0.01 to 0.3% by mass of a polyfunctional grafting agent is preferred.

Here, examples of the alkyl acrylate having 1 to 8 carbon atoms in the alkyl group include methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, s-butyl acrylate, 2-ethylhexyl acrylate, and the like. And n-butyl acrylate are preferably used.

The proportion of the alkyl acrylate unit in the innermost hard layer polymer (a) is 1 to 20% by mass. When the unit is less than 1% by mass, the thermal decomposability of the polymer is increased, while the unit is 20% by mass. If it exceeds 50%, the glass transition temperature of the innermost hard layer polymer (c) is lowered, and the impact resistance imparting effect of the three-layer structure acrylic granular composite is lowered.

Examples of the polyfunctional grafting agent include polyfunctional monomers having different polymerizable functional groups, such as allyl esters of acrylic acid, methacrylic acid, maleic acid, and fumaric acid, and allyl methacrylate is preferably used. . The polyfunctional grafting agent is used to chemically bond the innermost hard layer polymer and the soft layer polymer, and the ratio used during the innermost hard layer polymerization is 0.01 to 0.3% by mass. .

The crosslinked soft layer polymer (b) constituting the acrylic granular composite is an alkyl acrylate having from 9 to 8 carbon atoms having an alkyl group of 1 to 8 in the presence of the innermost hard layer polymer (a). What is obtained by polymerizing a monomer mixture consisting of 10% by mass, 0.01 to 5% by mass of a multifunctional crosslinking agent and 0.5 to 5% by mass of a multifunctional grafting agent is preferred.

Here, n-butyl acrylate or 2-ethylhexyl acrylate is preferably used as the alkyl acrylate having 4 to 8 carbon atoms in the alkyl group.

In addition to these polymerizable monomers, it is possible to copolymerize 25% by mass or less of other monofunctional monomers capable of copolymerization.

Examples of other monofunctional monomers that can be copolymerized include styrene and substituted styrene derivatives. As the ratio of the alkyl acrylate having 4 to 8 carbon atoms in the alkyl group and styrene increases, the glass transition temperature of the produced polymer (b) decreases as the former increases, that is, it can be softened.

On the other hand, from the viewpoint of the transparency of the resin assembly, the refractive index of the soft layer polymer (b) at room temperature is set to the innermost hard layer polymer (a), the outermost hard layer polymer (c), and the hard heat. It is more advantageous to make it closer to the plastic acrylic resin, and the ratio between them is selected in consideration of these.

For example, in applications where the coating layer thickness is small, it is not always necessary to copolymerize styrene.

As the polyfunctional grafting agent, those mentioned in the section of the innermost layer hard polymer (a) can be used. The polyfunctional grafting agent used here is used to chemically bond the soft layer polymer (b) and the outermost hard layer polymer (c), and the proportion used during the innermost hard layer polymerization is impact resistance. From the viewpoint of the effect of imparting properties, 0.5 to 5% by mass is preferable.

As the polyfunctional crosslinking agent, generally known crosslinking agents such as divinyl compounds, diallyl compounds, diacrylic compounds, dimethacrylic compounds and the like can be used, but polyethylene glycol diacrylate (molecular weight 200 to 600) is preferably used.

The polyfunctional cross-linking agent used here is used to generate a cross-linked structure during the polymerization of the soft layer (b) and to exhibit the effect of imparting impact resistance. However, if the above-mentioned polyfunctional grafting agent is used during the polymerization of the soft layer, the polyfunctional crosslinking agent is not an essential component because the crosslinked structure of the soft layer (b) is generated to some extent. Is preferably 0.01 to 5% by weight from the viewpoint of imparting impact resistance.

The outermost hard layer polymer (c) constituting the multi-layer structure acrylic granular composite has a methyl methacrylate of 80 to 99 mass in the presence of the innermost hard layer polymer (a) and the soft layer polymer (b). % And a monomer mixture comprising 1 to 20% by mass of an alkyl acrylate having 1 to 8 carbon atoms in the alkyl group is preferred.

Here, as the acrylic alkylate, those described above are used, but methyl acrylate and ethyl acrylate are preferably used. The proportion of the alkyl acrylate unit in the outermost hard layer (c) is preferably 1 to 20% by mass.

Also, during the polymerization of the outermost hard layer (c), an alkyl mercaptan or the like can be used as a chain transfer agent to adjust the molecular weight for the purpose of improving compatibility with the acrylic resin.

In particular, it is preferable to provide the outermost hard layer with a gradient such that the molecular weight gradually decreases from the inside toward the outside in order to improve the balance between elongation and impact resistance. As a specific method, the monomer mixture for forming the outermost hard layer is divided into two or more, and the molecular weight is increased from the inside by a method of sequentially increasing the amount of chain transfer agent added each time. It is possible to make it smaller toward the outside.

The molecular weight formed at this time can also be examined by polymerizing the monomer mixture used each time under the same conditions, and measuring the molecular weight of the obtained polymer.

The particle diameter of the acrylic granular composite which is a multilayer structure polymer preferably used in the present invention is not particularly limited, but is preferably 10 nm or more and 1000 nm or less, and more preferably 20 nm or more and 500 nm or less. More preferably, it is most preferably 50 nm or more and 400 nm or less.
By using fine particles having a large particle size, it is possible to obtain a sufficient effect with a smaller addition amount, which is preferable. However, if there is a large difference in the refractive index with the acrylic resin, the transparency of the film may be impaired. Therefore, it is important to approximate the refractive indexes of both.

In the acrylic granular composite that is a multilayer structure polymer preferably used in the present invention, the mass ratio of the core and the shell is not particularly limited, but when the entire multilayer structure polymer is 100 parts by mass, The core layer is preferably 50 parts by mass or more and 90 parts by mass or less, and more preferably 60 parts by mass or more and 80 parts by mass or less.

When the ratio of the core layer is less than 50 parts by mass, when the film formed is subjected to processing such as stretching, the particles are deformed to cause a refractive index difference between the resin and the particles, resulting in the transparency of the film. There is a risk of damaging sex.

Examples of such commercially available multilayered acrylic granular composites include, for example, “Metablene” manufactured by Mitsubishi Rayon Co., “Kane Ace” manufactured by Kaneka Chemical Co., Ltd., “Paralloid” manufactured by Kureha Chemical Co., Ltd., Rohm and Haas “Acryloid” manufactured by KK, “Staffyroid” manufactured by Ganz Kasei Kogyo Co., Ltd., “Parapet SA” manufactured by Kuraray Co., Ltd., and the like can be used alone or in combination.

In addition, specific examples of the acrylic particles that are graft copolymers that are preferably used as the acrylic particles preferably used in the present invention include unsaturated carboxylic acid ester monomers, unsaturated monomers in the presence of a rubbery polymer. A graft copolymer obtained by copolymerizing a monomer mixture comprising a saturated carboxylic acid monomer, an aromatic vinyl monomer, and, if necessary, other vinyl monomers copolymerizable therewith. Can be mentioned.

There is no particular limitation on the rubbery polymer used for the acrylic particles that are the graft copolymer, but diene rubber, acrylic rubber, ethylene rubber, and the like can be used. Specific examples include polybutadiene, styrene-butadiene copolymer, block copolymer of styrene-butadiene, acrylonitrile-butadiene copolymer, butyl acrylate-butadiene copolymer, polyisoprene, butadiene-methyl methacrylate copolymer. , Butyl acrylate-methyl methacrylate copolymer, butadiene-ethyl acrylate copolymer, ethylene-propylene copolymer, ethylene-propylene-diene copolymer, ethylene-isoprene copolymer, and ethylene-acrylic acid Examples thereof include a methyl copolymer. These rubbery polymers can be used alone or in a mixture of two or more.

Further, it is preferable that the refractive indexes of the acrylic resin and the acrylic particles are close to each other because the transparency of the acrylic resin-containing film of the present invention can be obtained. Specifically, the refractive index difference between the acrylic particles and the acrylic resin is preferably 0.05 or less, more preferably 0.02 or less, and particularly preferably 0.01 or less.

In order to satisfy such a refractive index condition, a method of adjusting the monomer unit composition ratio of the acrylic resin and / or a composition ratio of the rubbery polymer or monomer used in the acrylic particles is prepared. Depending on the method, the difference in refractive index can be reduced, and an acrylic resin-containing film excellent in transparency can be obtained.

Note that the difference in refractive index referred to here means that the acrylic resin-containing film of the present invention is sufficiently dissolved in a solvent in which the acrylic resin is soluble to obtain a cloudy solution, which is subjected to an operation such as centrifugation. After separating the soluble part and the insoluble part and purifying the soluble part (acrylic resin) and the insoluble part (acrylic particles), the difference in the measured refractive index (23 ° C., measurement wavelength: 550 nm) is shown.

In the present invention, the method of blending the acrylic particles with the acrylic resin is not particularly limited, and after blending the acrylic resin and other optional components in advance, usually at 200 to 350 ° C. while adding the acrylic particles, uniaxial or biaxial A method of uniformly melt-kneading with a shaft extruder is preferably used.

In addition, a method in which a solution in which acrylic particles are dispersed in advance is added to and mixed with a solution (dope solution) in which an acrylic resin and a cellulose ester resin are dissolved, and a solution in which acrylic particles and other optional additives are dissolved and mixed. A method such as in-line addition can be used.

Commercially available acrylic particles can also be used as the acrylic particles of the present invention. For example, Staphyloid AC-3355 (manufactured by Ganz Kasei Co., Ltd.), Delpet SRB215 (manufactured by Asahi Kasei Chemicals Co., Ltd.) and the like can be mentioned.

The acrylic resin-containing film of the present invention preferably contains 0.05 to 45% by mass of acrylic particles based on the total mass of the resin constituting the film.

<Film formation>
As a method for producing the acrylic resin-containing film of the present invention, production methods such as an inflation method, a T-die method, a calendar method, a cutting method, a casting method, an emulsion method, and a hot press method can be used. From the viewpoints of suppressing foreign matter defects and optical defects such as die lines, solution casting by casting is preferred.

(Organic solvent)
The organic solvent useful for forming the dope when the acrylic resin-containing film of the present invention is produced by the solution casting method is not limited as long as it dissolves acrylic resin, cellulose ester resin, and other additives simultaneously. Can be used.

For example, as a chlorinated organic solvent, methylene chloride, as a non-chlorinated organic solvent, methyl acetate, ethyl acetate, amyl acetate, acetone, tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, cyclohexanone, ethyl formate, 2,2,2-trifluoroethanol, 2,2,3,3-hexafluoro-1-propanol, 1,3-difluoro-2-propanol, 1,1,1,3,3,3-hexafluoro- 2-methyl-2-propanol, 1,1,1,3,3,3-hexafluoro-2-propanol, 2,2,3,3,3-pentafluoro-1-propanol, nitroethane, etc. Methylene chloride, methyl acetate, ethyl acetate and acetone can be preferably used. In addition to the above organic solvent, the dope preferably contains 1 to 40% by mass of a linear or branched aliphatic alcohol having 1 to 4 carbon atoms. When the proportion of alcohol in the dope increases, the web gels and peeling from the metal support becomes easy, and when the proportion of alcohol is small, the acrylic resin and cellulose ester resin dissolve in a non-chlorine organic solvent system. There is also a role to promote.

In particular, in a solvent containing methylene chloride and a linear or branched aliphatic alcohol having 1 to 4 carbon atoms, at least 15 to 45 mass in total of at least three kinds of acrylic resin, cellulose ester resin, and acrylic fine particles. It is preferable that the dope composition is dissolved in%.

The ratio of methylene chloride to aliphatic alcohol (MA represented by the following formula (i)) is preferably 4-20.

Formula (i): MA = mass of aliphatic alcohol / (mass of aliphatic alcohol + mass of methylene chloride) × 100
Examples of the linear or branched aliphatic alcohol having 1 to 4 carbon atoms include methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol, and tert-butanol. Ethanol is preferred because of the stability of these dopes, the relatively low boiling point, and good drying properties.

Hereinafter, a preferable method for forming the acrylic resin-containing film of the present invention will be described.

1) Dissolution step A step of dissolving the acrylic resin, cellulose ester resin, acrylic resin, and additive in an organic solvent mainly composed of a good solvent for the acrylic resin and cellulose ester resin while stirring in the dissolution vessel to form a dope, Alternatively, the dope is formed by mixing the acrylic resin and the cellulose ester resin solution with the acrylic resin solution and the additive solution.

For dissolution of acrylic resin and cellulose ester resin, a method carried out at normal pressure, a method carried out below the boiling point of the main solvent, a method carried out under pressure above the boiling point of the main solvent, JP-A-9-95544 and JP-A-9- Various dissolution methods can be used such as a method performed by a cooling dissolution method as described in JP-A-95557 or JP-A-9-95538, a method performed at high pressure as described in JP-A No. 11-21379, In particular, a method of pressurizing at a temperature equal to or higher than the boiling point of the main solvent is preferable.

The total of the three types of acrylic resin, cellulose ester resin, and acrylic fine particles in the dope is preferably in the range of 15 to 45% by mass. An additive is added to the dope during or after dissolution to dissolve and disperse, then filtered through a filter medium, defoamed, and sent to the next step with a liquid feed pump.

For the filtration, it is preferable to use a filter medium having a collected particle diameter of 0.5 to 5 μm and a drainage time of 10 to 25 sec / 100 ml. In this method, the aggregate remaining when the fine particles are dispersed and the aggregate generated when the main dope is added are only aggregated by using a filter medium having a collected particle diameter of 0.5 to 5 μm and a drainage time of 10 to 25 sec / 100 ml. Can be removed. In the main dope, since the concentration of fine particles is sufficiently thinner than that of the additive solution, aggregates do not adhere to each other during filtration and the filtration pressure does not increase rapidly.

FIG. 1 is a diagram schematically showing a dope preparation step, a casting step, and a drying step of a solution casting film forming method preferable for the present invention. Large agglomerates are removed from the acrylic fine particle charging vessel 41 by the filter 44 and fed to the stock vessel 42. Thereafter, the acrylic fine particle additive solution is added from the stock kettle 42 to the main dope dissolving kettle 1. Thereafter, the main dope solution is filtered by the main filter 3, and an ultraviolet absorbent additive solution is added in-line from 16 to this.

In many cases, the main dope may contain about 10 to 50% by mass of the recycled material. Since the return material contains acrylic fine particles, it is preferable to control the addition amount of the acrylic fine particle addition liquid in accordance with the addition amount of the return material. Recycled material is a finely pulverized acrylic resin-containing film that is generated when an acrylic resin-containing film is formed. The original fabric is used.
Moreover, what knead | mixed and pelletized acrylic resin and acrylic fine particle beforehand can be used preferably.

2) Casting process An endless metal belt 31, such as a stainless steel belt or a rotating metal drum, which feeds the dope through a liquid feed pump (for example, a pressurized metering gear pump) to the pressure die 30 and transfers it infinitely. This is a step of casting the dope from the pressure die slit to the casting position on the support.

¡Pressure dies that can adjust the slit shape of the die base and make the film thickness uniform are preferred. The pressure die includes a coat hanger die and a T die, and any of them is preferably used. The surface of the metal support is a mirror surface. In order to increase the film forming speed, two or more pressure dies may be provided on the metal support, and the dope amount may be divided and stacked. Or it is also preferable to obtain the film of a laminated structure by the co-casting method which casts several dope simultaneously.

3) Solvent evaporation step In the step of evaporating the solvent by heating the web (the dope is cast on the casting support and the formed dope film is called “web”) on the casting support. is there.

To evaporate the solvent, there are a method of blowing air from the web side and / or a method of transferring heat from the back side of the support by a liquid, a method of transferring heat from the front and back by radiant heat, and the like. High efficiency and preferable. A method of combining them is also preferably used. The web on the support after casting is preferably dried on the support in an atmosphere of 40 to 100 ° C. In order to maintain the atmosphere at 40 to 100 ° C., it is preferable to apply hot air at this temperature to the upper surface of the web or heat by means such as infrared rays.

Depending on the film thickness at the time of casting, the web is preferably peeled from the support in the range of 30 to 240 seconds from the viewpoint of productivity, surface quality, peelability and the like. More preferably, it is 60 to 180 seconds.

4) Peeling process It is the process of peeling the web which the solvent evaporated on the metal support body in a peeling position. The peeled web is sent to the next process.

The temperature at the peeling position on the metal support is preferably 10 to 40 ° C., more preferably 11 to 30 ° C.

The residual solvent amount at the time of peeling of the web on the metal support at the time of peeling is preferably peeled in the range of 50 to 120% by mass depending on the strength of drying conditions, the length of the metal support, and the like. When peeling off at a time when the amount of residual solvent is larger, if the web is too soft, the flatness at the time of peeling will be impaired, and slippage and vertical stripes are likely to occur due to peeling tension, so the balance between economic speed and quality Residual solvent concentration (%) is determined.

The residual solvent concentration (%) of the web is defined by the following formula (ii).

Formula (ii): Residual solvent concentration (%) = (mass of cast film−mass of dry film) / mass of dry film × 100 (%)
Note that the heat treatment for measuring the residual solvent amount represents performing heat treatment at 115 ° C. for 1 hour.

The peeling tension when peeling the metal support from the film is usually preferably 196 to 245 N / m. However, when wrinkles are likely to occur during peeling, peeling with a tension of 190 N / m or less is preferable. It is preferable to peel at a minimum tension of ˜166.6 N / m, and then peel at a minimum tension of ˜137.2 N / m, and particularly preferable to peel at a minimum tension of ˜100 N / m.

In the present invention, the temperature at the peeling position on the metal support is preferably −50 to 40 ° C., more preferably 10 to 40 ° C., and most preferably 15 to 30 ° C.

5) Drying and stretching step After peeling, a drying device 35 that alternately conveys the web through a plurality of rolls arranged in the drying device and / or a tenter stretching device 34 that clips and conveys both ends of the web with a clip are used. And dry the web.

The drying means is generally to blow hot air on both sides of the web, but there is also a means to heat by applying microwaves instead of wind. Too rapid drying tends to impair the flatness of the finished film. Drying at a high temperature is preferably performed from about 8% by mass or less of the residual solvent. Throughout, drying is generally performed at 40-250 ° C. In particular, drying at 40 to 160 ° C. is preferable.

When using a tenter stretching apparatus, it is preferable to use an apparatus capable of independently controlling the film gripping length (distance from the start of gripping to the end of gripping) by the left and right gripping means of the tenter. In the tenter process, it is also preferable to intentionally create sections having different temperatures in order to improve planarity. It is also preferable to provide a neutral zone between different temperature zones so that the zones do not interfere with each other.

The stretching operation may be performed in multiple stages, and it is also preferable to perform biaxial stretching in the casting direction and the width direction. When biaxial stretching is performed, simultaneous biaxial stretching may be performed or may be performed stepwise. In this case, stepwise means that, for example, stretching in different stretching directions can be sequentially performed, stretching in the same direction is divided into multiple stages, and stretching in different directions is added to any one of the stages. Is also possible. That is, for example, the following stretching steps are possible.

-Stretch in the casting direction-Stretch in the width direction-Stretch in the casting direction-Stretch in the casting direction-Stretch in the width direction-Stretch in the width direction-Stretch in the casting direction-Stretch in the casting direction Simultaneous biaxial stretching includes stretching in one direction and contracting the other while relaxing the tension. The preferred draw ratio for simultaneous biaxial stretching can be in the range of x1.01 to x1.5 in both the width direction and the longitudinal direction.

When the tenter is used, the amount of residual solvent in the web is preferably 20 to 100% by mass at the start of the tenter, and drying is preferably performed while the tenter is applied until the amount of residual solvent in the web is 10% by mass or less. More preferably, it is 5% by mass or less.

When performing the tenter, the drying temperature is preferably 30 to 150 ° C, more preferably 50 to 120 ° C, and most preferably 70 to 100 ° C.

In the tenter process, it is preferable that the temperature distribution in the width direction of the atmosphere is small from the viewpoint of improving the uniformity of the film. The temperature distribution in the width direction in the tenter process is preferably within ± 5 ° C, and within ± 2 ° C. Is more preferable, and within ± 1 ° C. is most preferable.

6) Winding step This is a step of winding up the acrylic resin-containing film by the winder 37 after the residual solvent amount in the web is 2% by mass or less, and by setting the residual solvent amount to 0.4% by mass or less. A film having good dimensional stability can be obtained.

As a winding method, a generally used one may be used, and there are a constant torque method, a constant tension method, a taper tension method, a program tension control method with a constant internal stress, etc., and these may be used properly.

The acrylic resin-containing film of the present invention is preferably a long film. Specifically, the acrylic resin-containing film is about 100 to 5000 m, and is usually in the form of a roll. The film width is preferably 1.3 to 4 m, more preferably 1.4 to 2 m.

The film thickness of the acrylic resin-containing film of the present invention is not particularly limited, but when used for a polarizing plate protective film described later, it is preferably 20 to 200 μm, more preferably 25 to 100 μm, and 30 to 80 μm. It is particularly preferred that

(Polarizer)
The polarizing plate used in the present invention can be produced by a general method. That is, it is preferable that an adhesive layer is provided on the back side of the acrylic resin-containing film of the present invention, and is bonded to at least one surface of a polarizer produced by immersion and stretching in an iodine solution. Further, surface treatment such as corona treatment can be performed as necessary. By performing the surface treatment, adhesion with the polarizer can be improved. The film may be used on the other surface, or another polarizing plate protective film may be used. For example, commercially available cellulose ester films (for example, Konica Minoltac KC8UX, KC4UX, KC5UX, KC8UY, KC4UY, KC12UR, KC8UCR-3, KC8UCR-4, KC8UCR-5, KV8UY-HA, KV8UX-RHA, KV8UX-RHA Etc.) are preferably used.

A polarizer, which is a main component of a polarizing plate, is an element that transmits only light having a plane of polarization in a certain direction. A typical polarizing film known at present is a polyvinyl alcohol polarizing film, which is a polyvinyl alcohol. There are one in which iodine is dyed on a system film and one in which dichroic dye is dyed. For the polarizer, a polyvinyl alcohol aqueous solution is formed into a film and dyed by uniaxial stretching or dyed or uniaxially stretched and then preferably subjected to a durability treatment with a boron compound.

As the adhesive used for the adhesive layer, an adhesive layer having a storage elastic modulus at 25 ° C. in the range of 1.0 × 10 ⁴ to 1.0 × 10 ⁹ Pa in at least a part of the adhesive layer is used. Preferably, a curable adhesive that forms a high molecular weight body or a crosslinked structure by various chemical reactions after the adhesive layer is applied and bonded is suitably used. Specific examples include, for example, urethane adhesives, epoxy adhesives, aqueous polymer-isocyanate adhesives, curable adhesives such as thermosetting acrylic adhesives, moisture curable urethane adhesives, polyether methacrylate types, Examples include anaerobic adhesives such as ester-based methacrylate type and oxidized polyether methacrylate, cyanoacrylate-based instant adhesives, acrylate-peroxide-based two-component instant adhesives, and the like. The adhesive may be a one-pack type or a mold that uses two or more liquids mixed before use. The adhesive may be a solvent system using an organic solvent as a medium, or an aqueous system such as an emulsion type, a colloidal dispersion type, or an aqueous solution type that is a medium containing water as a main component. It may be a solvent type. The concentration of the adhesive solution may be appropriately determined depending on the film thickness after bonding, the coating method, the coating conditions, and the like, and is usually 0.1 to 50% by mass.

(Liquid crystal display device)
By incorporating the polarizing plate bonded with the acrylic resin-containing film of the present invention into a liquid crystal display device, various liquid crystal display devices with excellent visibility can be produced. The polarizing plate according to the present invention is bonded to a liquid crystal cell via the adhesive layer or the like.

The polarizing plate according to the present invention is a reflective type, transmissive type, transflective type LCD or TN type, STN type, OCB type, HAN type, VA type (PVA type, MVA type), IPS type, etc. Preferably used. In particular, in a large-screen display device having a screen of 30 or more, especially 30 to 54, there is no white spot at the periphery of the screen and the effect is maintained for a long time. In addition, there was little color unevenness, glare and wavy unevenness, and the eyes were not tired even during long-time viewing.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.

Example 1
<Production of acrylic resin-containing film>
(Preparation of acrylic resin-containing film A1)
(Preparation of dope solution for A1)
BR85 (acrylic resin, manufactured by Mitsubishi Rayon Co., Ltd.) 70 parts by mass Cellulose ester (cellulose acetate propionate acyl group total substitution degree 2.75, acetyl group substitution degree 0.19, propionyl group substitution degree 2.56, Mw = 200000)
30 parts by mass Methylene chloride 264 parts by mass Ethanol 36 parts by mass (production of an acrylic resin-containing film)
The produced dope solution was uniformly cast on a stainless steel band support at a temperature of 22 ° C. and a width of 2 m using a belt casting apparatus. With the stainless steel band support, the solvent was evaporated until the residual solvent concentration (residual solvent amount) reached 100%, and the film was peeled off from the stainless steel band support with a peeling tension of 162 N / m. At this time, the time required from casting to peeling was 100 seconds. The peeled acrylic resin web was evaporated at 35 ° C., slit to 1.6 m width, and then dried at a drying temperature of 135 ° C. while being stretched 1.1 times in the width direction by a tenter. At this time, the residual solvent concentration when starting stretching with a tenter was 10% by mass. After stretching with a tenter and relaxing at 130 ° C for 5 minutes, drying was completed while transporting the drying zone at 120 ° C and 130 ° C with a number of rolls, slitting to a width of 1.5 m, and 10 mm wide at both ends of the film. A knurling process having a thickness of 5 μm was applied, and the film was wound around a 6-inch inner diameter core with an initial tension of 220 N / m and a final tension of 110 N / m to obtain an acrylic resin-containing film A1. The draw ratio in the MD direction (casting direction) calculated from the rotational speed of the stainless steel band support and the operating speed of the tenter was 1.1 times. The residual solvent concentration of the acrylic resin-containing film film A1 described in Table 1 was 0.1% by mass, the film thickness was 60 μm, and the winding number was 4000 m.

Hereinafter, acrylic resin-containing films A1 to A28 were produced in the same manner as the acrylic resin-containing film A1, except that the composition ratio of the acrylic resin and the cellulose ester resin was changed as shown in Table 1.

In addition, acrylic resin containing film A8, A11 added the following ultraviolet absorber and produced dope.

(A8)
Tinuvin 109 (Ciba Specialty Chemicals Co., Ltd.) 1.5 parts by mass Tinuvin 171 (Ciba Specialty Chemicals Co., Ltd.) 0.7 parts by mass (A11)
LA-31 (manufactured by ADEKA) 1.5 parts by mass KT75 (manufactured by Denki Kagaku Kogyo), Delpet 80N (manufactured by Asahi Kasei Chemicals), dialnal BR80, BR83, BR85, BR88 (manufactured by Mitsubishi Rayon) went. K1 (Mw: 800,000 acrylic resin, MMA-MA)
Table 1 shows the contents of the various acrylic resin-containing films A1 to A28.

In the column of cellulose ester resin in Table 1, the numbers in the columns indicated by the symbols ac, p, b, bz, and ph represent the degree of substitution of the substituents as follows.

ac: acetyl substitution degree, p: propionyl substitution degree, b: butyryl substitution degree, bz: benzoyl group, ph: phthalyl group, T: total substitution degree << Evaluation Method >>
First, the film material was sufficiently conditioned for one day and night under the condition of 23 ° C. and 55% RH.

(Tension softening point)
The following evaluation was performed using a Tensilon tester (ORIENTEC, RTC-1225A).

The acrylic resin-containing film is cut out at 120 mm (length) x 10 mm (width) and continuously heated at a heating rate of 30 ° C./min while being pulled with a tension of 10 N under the conditions of 23 ° C. and 55% RH. The temperature at that time was measured three times and the average was calculated.

(Ductile fracture)
Acrylic resin-containing film is cut out at 100 mm (length) x 10 mm (width), and the film overlaps exactly at the center in the vertical direction with a radius of curvature of 0 mm and a bending angle of 180 ° under the conditions of 23 ° C. and 55% RH. As described above, the folds were folded once into two, one into a mountain fold and one into a valley fold, and this evaluation was measured three times and evaluated as follows. In addition, breaking of evaluation here represents having broken and isolate | separated into two or more pieces.

○: Cannot be folded 3 times.

X: Fold at least once out of 3 times.

(Film deformation)
The film sample was left in an atmosphere of 90 ° C. and DRY (relative humidity 5% RH or less) for 1000 hours, and the degree of film deformation was visually observed under the conditions of 23 ° C. and 55% RH.

○: No film deformation.

Δ: Deformation of the film is observed.

X: Significant film deformation is observed.

(Cutting property)
The film was torn under conditions of 23 ° C. and 55% RH using a light load tear tester (manufactured by Toyo Seiki Co., Ltd.), and evaluated as follows.

◯: The tear surface is very smooth and is torn straight.

△: There is a slight burr on the tear surface, but it is torn straight.

X: There is a lot of burrs on the tear surface or it is not torn straight.

(Film appearance)
Regarding the produced film, the film appearance was visually evaluated under the condition of 23 ° C. and 55% RH, and evaluated as follows.

○: Very smooth flatness.

△: Slight creases, wrinkles and steps can be confirmed.

X: Clear, creased, and step can be confirmed.

Table 2 shows the above evaluation results.

As is apparent from the results shown in Table 2, it can be seen that the acrylic resin-containing film of the present invention is excellent in evaluation of the tension softening point, ductile fracture, film deformation, cutting property, and film appearance.

Example 2
In the production conditions of the films A1, A12, and A14 performed in Example 1, various acrylic resin-containing films A1-1 to A1-18, A12-1 to A12-8, and A14-1 to A14 were used under the conditions shown in Table 3. -4 was prepared and evaluated as follows.

Further, A14-5 was produced in the same manner as A14-1 except that 0.05% by mass of zonyl UR (manufactured by DuPont) was added to the dope of A14 as a release agent with respect to the mass of the dope.

(productivity)
Productivity was evaluated based on the following criteria.

○: Productivity is high with no failure or defect.

△: There are a lot of failures and defects, and productivity is inferior.

X: Many failures and defects and poor productivity.

(Film appearance)
In the same manner as described above, evaluation was performed based on the following criteria.

○: Very smooth flatness.

△: Slight creases, wrinkles and steps can be confirmed.

X: Clear, creased, and step can be confirmed.

(Haze)
With respect to each of the produced film samples, one film sample was measured according to JIS K-7136 using a haze meter (NDH2000 type, manufactured by Nippon Denshoku Industries Co., Ltd.).

Table 3 summarizes the contents and evaluation results of various acrylic resin-containing films.

As is clear from the results shown in Table 3, it can be seen that the acrylic resin-containing film of the present invention is excellent in evaluation of the productivity film appearance and haze.

Example 3
Film formation was carried out in the same manner except that BR85 was used in place of the acrylic resin (K1) under the production conditions for the A17 film, to produce an acrylic resin-containing film C1.

In addition, the following acrylic fine particles AP1, and commercially available acrylic fine particles, Staphyloid AC-3355 (manufactured by Ganz Kasei Co., Ltd.), Delpet SRB215 (manufactured by Asahi Kasei Chemicals Co., Ltd.) are manufactured in the same manner as C1 with the compositions shown in Table 4. Thus, acrylic resin-containing films C2 to C7 were produced.
<Preparation of acrylic fine particle AP1>
A reactor with a reflux condenser with an internal volume of 60 liters was charged with 38.2 liters of ion-exchanged water and 111.6 g of sodium dioctylsulfosuccinate, and the temperature was raised to 75 ° C. under a nitrogen atmosphere while stirring at a rotational speed of 250 rpm. The effect of oxygen was virtually eliminated. 0.36 g of APS was added, and after stirring for 5 minutes, a monomer mixture consisting of 1657 g of MMA, 21.6 g of BA, and 1.68 g of ALMA was added all at once. Completed.

Next, 3.48 g of APS was added, and after stirring for 5 minutes, a monomer mixture consisting of BA 8105 g, PEGDA (200) 31.9 g, and ALMA 264.0 g was continuously added over 120 minutes. Hold for a minute to complete the soft layer polymerization. Next, 1.32 g of APS was added, and after stirring for 5 minutes, a monomer mixture consisting of 2106 g of MMA and 201.6 g of BA was continuously added over 20 minutes. The polymerization of was completed. Next, 1.32 g of APS was added, and after 5 minutes, a monomer mixture consisting of 3148 g of MMA, 201.6 g of BA, and 10.1 g of n-OM was continuously added over 20 minutes, and the mixture was held for another 20 minutes after the addition was completed. Next, the temperature was raised to 95 ° C. and held for 60 minutes to complete the polymerization of the outermost hard layer 2.

A small amount of the polymer latex thus obtained was collected, and the particle diameter was measured by an electrophoretic light scattering photometer ELS-800 (manufactured by Otsuka Electronics Co., Ltd.) and found to be 0.10 μm. The remaining latex was put into a 3% by mass sodium sulfate warm aqueous solution, salted out and coagulated, and then dried after repeated dehydration and washing to obtain acrylic fine particles AP1 having a three-layer structure.

The above abbreviations are the following materials.

MMA; methyl methacrylate BA; n-butyl acrylate ALMA; allyl methacrylate PEGDA; polyethylene glycol diacrylate (molecular weight 200)
n-OM; n-octyl mercaptan APS; ammonium persulfate The contents and evaluation results of the various acrylic resin-containing films obtained above are shown in Tables 4 and 5. The evaluation method is the same as in Examples 1 and 2.

As is apparent from the results shown in Table 5, it can be seen that the acrylic resin-containing film of the present invention is excellent in the evaluation of haze, tension softening point, ductile fracture, film deformation, cutting property, and film appearance.

Claims

An acrylic resin-containing film containing an acrylic resin as a main constituent, containing an acrylic resin and a cellulose ester resin in a mass ratio of 95: 5 to 30:70, and having a total substitution degree of acyl groups of the cellulose ester resin 2.00 to 2.99, acetyl group substitution degree is 0.10 to 1.89, carbon number of acyl group other than acetyl group is 3 to 7, and weight average molecular weight is 75000 to 280000, An acrylic resin-containing film, wherein the resin-containing film has a haze of less than 1%, a tension softening point of 105 to 145 ° C., and does not cause ductile fracture.
The acrylic resin-containing film according to claim 1, comprising 0.05 to 45 parts by mass of acrylic fine particles with respect to 100 parts by mass of the total mass of the acrylic resin and the cellulose ester resin.
It is a manufacturing method of the acrylic resin containing film of Claim 1 or 2 which has the process of peeling after dope a dope composition to an endless belt, Comprising: The said dope composition is methylene chloride, carbon number A dope composition having a solid content of 15 to 45% by mass containing 1 to 4 linear or branched aliphatic alcohol, acrylic resin, and cellulose ester resin, wherein the ratio of methylene chloride to aliphatic alcohol ( MA represented by the following formula (i) is 4 to 20, and 30 to 240 seconds after casting the dope composition onto an endless belt, the residual solvent concentration represented by the following formula (ii) is 50 A method for producing an acrylic resin-containing film, wherein the film is peeled off in a state of ˜120%.
Formula (i): MA = mass of aliphatic alcohol / (mass of aliphatic alcohol + mass of methylene chloride) × 100
Formula (ii): Residual solvent concentration (%) = (mass of cast film−mass of dry film) / mass of dry film × 100 (%)