JP2014152281A - Method for producing transparent resin laminate film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a resin laminate film capable of being suitably used for a display faceplate which is excellent in transparency, surface hardness and scratch resistance and suppressed in generation of curls.SOLUTION: There is provided a transparent resin laminate film having a first hard coat layer, a layer of a transparent resin film and a second hard coat layer in order from the front side, wherein a coating material for forming a hard coat and conditions of forming a hard coat are selected so that a force causing the transparent resin laminate film to curl in one direction and a force causing the transparent resin laminate film to curl in the other direction are offset to become zero.

Description

The present invention relates to a method for producing a transparent resin laminated film. More particularly, the present invention relates to a method for producing a resin laminated film that can be suitably used for a display face plate and the like that are excellent in transparency, surface hardness, and scratch resistance and curling is suppressed.

Conventionally, a transparent resin film, for example, a film made of an acrylic resin or a polycarbonate resin has been used as a display face plate instead of glass. In these applications, the transparent resin film has a lower surface hardness and scratch resistance than glass, so it is generally performed to form a hard coat layer on the surface by applying and curing a curable resin paint. ing. On the other hand, when the hard coat layer is formed, the laminated film is curled, and there is a problem that the process of processing the laminated film into a display is hindered.

Therefore, many proposals have been made as techniques for suppressing the occurrence of curling.
(1) An active energy ray-curable resin composition having small shrinkage during curing (for example, Patent Documents 1 and 2).
(2) A composition for forming a hard coat layer that uses a monomer that is highly permeable to a substrate and a monomer that is difficult to penetrate, that is, (a) dimethyl carbonate, (b) three or more unsaturated groups in one molecule A compound having a double bond and a weight average molecular weight of 500 or more, (c) a compound having two or less unsaturated double bonds in one molecule and a weight average molecular weight of less than 500, and (d) light A composition for forming a hard coat layer containing a polymerization initiator (Patent Document 3).
(3) A method in which the surface portion of the coating layer is heated to a higher temperature than other portions to selectively cure the surface portion, that is, curing that can be cured by heat on the surface of the base material made of a thermoplastic resin. A step (A) of forming a coating layer by applying a functional material, and a step (B) of obtaining a hard coat layer by curing the coating layer, wherein the step (B) is a surface of the coating layer. Including a step (b1) in which the portion is heated to a temperature higher than the portion other than the surface portion of the coating layer and the base material, and the maximum heating temperature Th1 of the coating layer in the step (b1), The manufacturing method of a hard coat film whose difference Th1-Ts with Vicat softening temperature Ts of a thermoplastic resin is larger than -20 degreeC (patent document 4).
(4) A method for producing a hard coat film comprising a step of coating a composition containing a photopolymerizable compound on a substrate and then polymerizing the photopolymerizable compound by light irradiation to form a hard coat layer. Then, in the step of forming the hard coat layer, the film surface temperature when performing the light irradiation is controlled to 20 ° C. to 30 ° C., the light irradiation is performed twice or more, and 10 seconds to 60 seconds between each light irradiation. A manufacturing method of a hard coat film which provides a non-irradiation time of 2 seconds (Patent Document 5)
However, any technique for suppressing the occurrence of curling is insufficient to obtain a transparent resin laminated film used for a display face plate.

JP 2012-062385 A JP 2012-180487 A JP 2012-141459 A JP 2012-166140 A JP 2012-215705 A

The subject of this invention is providing the manufacturing method of the resin laminated | multilayer film which can be used suitably for the display faceplate etc. which were excellent in transparency, surface hardness, and scratch resistance, and the generation | occurrence | production of the curl was suppressed. is there.

As a result of earnest research, the present inventor tried to curl the transparent resin laminated film to one side in the transparent resin laminated film having the first hard coat layer, the transparent resin film layer, and the second hard coat layer in order from the surface side. It has been found that the above-described problem can be achieved by canceling out the force to be curled and the force to curl to the other to zero.

That is, the present invention is a method for producing a transparent resin laminated film,
(1) The transparent resin laminated film has a first hard coat layer, a transparent resin film layer, and a second hard coat layer in this order from the surface side.
(2) The first hard coat layer forming paint and the second hard coat layer forming paint have the same potential to generate a force to curl the transparent resin laminated film,
(3) After applying the first hard coat layer-forming paint on one surface of the transparent resin film and the second hard coat layer-forming paint on the other surface so as to have the same wet thickness, In this method, the hard coat layer and the second hard coat layer are cured so as to have the same thickness after curing.

The transparent resin laminated film obtained by the production method of the present invention is excellent in transparency, surface hardness, scratch resistance, and curling is suppressed, so that it can be suitably used as a display face plate such as a touch panel. it can.

The transparent resin laminated film obtained by the production method of the present invention has a first hard coat layer, a transparent resin film layer, and a second hard coat layer in order from the surface side. Thus, by providing the hard coat layer on both sides of the transparent resin film, the transparent resin laminated film will be curled to one side (hereinafter abbreviated as curling force) and curled to the other side. Both of these forces will work. The occurrence of curling can be suppressed by canceling these two curling forces to zero.

In order to cancel the above two forces to zero, firstly generate the curling force of the first hard coat layer forming paint and the second hard coat layer forming paint curl force. It is necessary to make the potential to be the same. When the potentials for generating the curl force are different, it is industrially difficult to make the curl force of the first hard coat layer and the curl force of the second hard coat layer the same.

The potential for generating the curling force of the paint can be made the same by setting the components that are strong control factors (hereinafter abbreviated as control factor components) to the same composition.

If only curling suppression needs to be considered, the first hard coat layer forming paint and the second hard coat layer forming paint are all prepared with the same composition, that is, the same paint. May be. However, when the obtained transparent resin laminated film is used for a display face plate, contradictory characteristics are required on the front surface side and the back surface side. For example, the front surface side (touch surface side) is required to have stain resistance (a property of repelling hand grease), while the back surface side is required to have printability (oil-based ink wettability). Therefore, as described above, the dominant factor component has the same composition, while the component that has no substantial influence on the potential to generate the curling force of the paint (hereinafter abbreviated as a non-dominant factor component) is curled. By designing the coating material according to various required characteristics other than the suppression of curling, both curling suppression and other required characteristics can be achieved.

Here, “the same potential for generating the curling force” should not be interpreted as completely the same in a strict physicochemical sense. It should be construed as the same within the range of quality control that is usually performed industrially. For example, paints prepared according to a recipe that uses the same grade for each of the raw materials containing the governing factor component and have the same mixing ratio of these raw materials fall under “the same potential to generate curling power” .

Industrially, even if the grade is the same, the quality is controlled within a certain range of runout, and the quality is controlled within the range of some runout in the preparation of the paint. Therefore, the same lot / batch of the same grade is used for each raw material containing the controlling factor component, and the same lot / batch intermediate paint prepared according to the same paint recipe is used for both hard coat layer forming paints. It is preferable to prepare for the preparation and obtain the first hard coat layer forming paint and the second hard coat layer forming paint by blending each non-dominating factor component in the intermediate paint, respectively.

Next, after coating the first hard coat layer forming paint on one side of the transparent resin film and the second hard coat layer forming paint on the other side so as to have the same wet thickness, It is necessary to cure the first hard coat layer and the second hard coat layer so that the thickness after curing is the same. By setting the same wet thickness and the same thickness after curing, the first hard coat layer and the second hard coat layer have the same degree of cure (shrinkage) of the paint, that is, the curl force of the paint is generated. The potential is pulled out the same, and the curling force of the first hard coat layer and the curling force of the second hard coat layer can be made the same. When at least one of the wet thickness and the thickness after curing is different, the curl force of the first hard coat layer and the curl force of the second hard coat layer cannot be made the same, and curling occurs. .

Here, “the same wet thickness” and “the same thickness after curing” should not be construed as completely the same thickness in a strict physicochemical sense. The thickness should be construed as the same thickness within the range of process / quality control that is usually performed in industry. This is because the object of the present application can be sufficiently achieved if the thickness is the same within the range of the amplitude of the process and quality control that are usually performed industrially.

For example, since the thickness after curing is usually controlled in process and quality with a width of about −1 to +1 μm, the thickness after curing of 19 μm and 21 μm should be interpreted as the same. Similarly, since the wet thickness is usually subjected to process / quality control with a width of about −2 to +2 μm, the wet thickness of 38 μm and the same of 42 μm should be interpreted as the same.

Needless to say, these process / quality control widths are preferably as narrow as possible. The thickness after curing is preferably about -0.5 to +0.5 μm, and the wet thickness is preferably about −1 to +1 μm. Should be quality controlled.

Further, it is preferable that the first hard coat layer and the second hard coat layer have the same method for curing the paint. As such a curing method, for example, when an active energy ray-curable coating is used, a drying / curing furnace having the same irradiation device on each of the first hard coat layer side and the second hard coat layer side And a method of curing both layers at the same time by operating both irradiation devices to have the same irradiation pattern. Here, “same” should be construed to be the same within the scope of process control that is usually performed industrially.

As a coating material for forming the first hard coat layer and the second hard coat layer, in order to suppress the occurrence of curling, the controlling factor component has the same composition, and the potential to generate the force to curl the transparent resin laminated film There is no particular limitation except that the ability is the same and the transparency is excellent for the purpose of being used for the display face plate, and any paint can be used.

Examples of preferable paints include those capable of forming a hard coat excellent in surface hardness and scratch resistance. Specifically, an active energy ray-curable resin composition can be exemplified.

The active energy ray-curable resin composition can be polymerized and cured by active energy rays such as ultraviolet rays and electron beams to form a coating film. For example, polyurethane (meth) acrylate, polyester (meta ) Acrylate, polyacryl (meth) acrylate, epoxy (meth) acrylate, polyalkylene glycol poly (meth) acrylate, and (meth) acryloyl group-containing prepolymer or oligomer such as polyether (meth) acrylate; methyl (meth) Acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentenyl (meth) acrylate Rate, dicyclopentenyloxyethyl (meth) acrylate, phenyl (meth) acrylate, phenyl cellosolve (meth) acrylate, 2-methoxyethyl (meth) acrylate, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, 2 -(Meth) acryloyl group-containing monofunctional reactive monomers such as acryloyloxyethyl hydrogen phthalate, dimethylaminoethyl (meth) acrylate, trifluoroethyl (meth) acrylate, and trimethylsiloxyethyl methacrylate; N-vinylpyrrolidone, styrene, etc. Monofunctional reactive monomers: diethylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate Polyethylene glycol di (meth) acrylate, 2,2′-bis (4- (meth) acryloyloxypolyethyleneoxyphenyl) propane, and 2,2′-bis (4- (meth) acryloyloxypolypropyleneoxyphenyl) (Meth) acryloyl group-containing bifunctional reactive monomers such as propane; (meth) acryloyl group-containing trifunctional reactive monomers such as trimethylolpropane tri (meth) acrylate and trimethylolethane tri (meth) acrylate; pentaerythritol tetra ( One or more selected from (meth) acryloyl group-containing tetrafunctional reactive monomers such as (meth) acrylate; and (meth) acryloyl group-containing hexafunctional reactive monomers such as dipentaerythritol hexaacrylate, or the above one or more Configure A composition containing a resin as a monomer together with a compound having two or more isocyanate groups (—N═C═O) and / or a photopolymerization initiator in one molecule can be given. The components exemplified here are all dominant factor components.

In this specification, (meth) acrylate means acrylate or methacrylate.

Examples of the compound having two or more isocyanate groups in one molecule include methylene bis-4-cyclohexyl isocyanate; a trimethylolpropane adduct of tolylene diisocyanate, a trimethylolpropane adduct of hexamethylene diisocyanate, and a trimethylolpropane adduct of isophorone diisocyanate. Polyisocyanates such as methylolpropane adduct, isocyanurate of tolylene diisocyanate, isocyanurate of hexamethylene diisocyanate, isocyanurate of isophorone diisocyanate, biuret of hexamethylene diisocyanate; and block isocyanates of the above polyisocyanates A urethane cross-linking agent can be used. These can be used alone or in combination of two or more. Further, at the time of crosslinking, a catalyst such as dibutyltin dilaurate or dibutyltin diethylhexoate may be added as necessary. The components exemplified here are all dominant factor components.

Examples of the photopolymerization initiator include benzophenone, methyl-o-benzoylbenzoate, 4-methylbenzophenone, 4,4′-bis (diethylamino) benzophenone, methyl o-benzoylbenzoate, 4-phenylbenzophenone, 4- Benzophenone compounds such as benzoyl-4'-methyldiphenyl sulfide, 3,3 ', 4,4'-tetra (tert-butylperoxycarbonyl) benzophenone, 2,4,6-trimethylbenzophenone; benzoin, benzoin methyl ether, Benzoin compounds such as benzoin ethyl ether, benzoin isopropyl ether and benzyl methyl ketal; acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexyl phenyl ketone Acetophenone compounds; anthraquinone compounds such as methylanthraquinone, 2-ethylanthraquinone, 2-amylanthraquinone; thioxanthone compounds such as thioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone; alkyls such as acetophenone dimethyl ketal Phenone compounds; triazine compounds; biimidazole compounds; acyl phosphine oxide compounds; titanocene compounds; oxime ester compounds; oxime phenylacetate compounds; hydroxy ketone compounds; and aminobenzoate compounds. Can do. These can be used alone or in combination of two or more. The components exemplified here are all dominant factor components.

The active energy ray-curable resin composition may contain one kind of additives such as an antioxidant, a weather resistance stabilizer, a light resistance stabilizer, an ultraviolet absorber, a heat stabilizer, a colorant, and a filler as necessary. Or two or more of them may be contained. The components exemplified here are all dominant factor components.

In addition, the active energy ray-curable resin composition may include one kind of additives such as an antistatic agent, a surfactant, a leveling agent, a thixotropic agent, a stain prevention agent, and a printability improving agent, if necessary. Two or more kinds may be included. All of the components exemplified here are non-dominating factor components.

Preferable optional components include fine particles having a particle diameter of 1 nm to 300 nm. The hardness of the hard coat layer can be increased by using the fine particles in an amount of 1 to 300 parts by weight, preferably 100 to 200 parts by weight, based on 100 parts by weight of the active energy ray-curable resin component. The fine particles are a dominant factor component. In addition, all the components exemplified in the following paragraphs 0029 to 0031 are also governing factor components.

As the fine particles, either inorganic fine particles or organic fine particles can be used. Examples of the inorganic fine particles include silica (silicon dioxide); metal oxide fine particles such as aluminum oxide, zirconia, titania, zinc oxide, germanium oxide, indium oxide, tin oxide, indium tin oxide, antimony oxide, and cerium oxide; Metal fluoride fine particles such as magnesium fluoride and sodium fluoride; metal fine particles; metal sulfide fine particles; metal nitride fine particles; Examples of the organic fine particles include resin beads such as a styrene resin, an acrylic resin, a polycarbonate resin, an ethylene resin, and a cured resin of an amino compound and formaldehyde. These can be used alone or in combination of two or more.

In addition, for the purpose of increasing the dispersibility of the fine particles in the paint or increasing the hardness of the obtained hard coat layer, the surface of the fine particles is treated with a silane coupling agent such as vinylsilane or aminosilane; a titanate coupling agent; aluminum Nate coupling agents; Organic compounds having an ethylenically unsaturated bond group such as (meth) acryloyl group, vinyl group and allyl group and reactive functional groups such as epoxy group; Surface treatment agents such as fatty acids and fatty acid metal salts You may use what was processed by.

Among these, in order to obtain a hard coat layer with higher hardness, fine particles of silica and aluminum oxide are preferable, and fine particles of silica are more preferable. Examples of commercially available silica fine particles include Snowtex (trade name) manufactured by Nissan Chemical Industries, Ltd., Quartron (trade name) manufactured by Fuso Chemical Industries, Ltd., and the like.

The particle diameter of the fine particles needs to be 300 nm or less in order to maintain the transparency of the hard coat layer. If the particle size is coarse, the effect of improving the hardness of the hard coat layer may not be obtained. Preferably it is 200 nm or less, More preferably, it is 120 nm or less. On the other hand, there is no particular lower limit of the particle diameter, but normally available particles are at most about 1 nm even if they are fine.

In this specification, the particle size of the fine particles is the cumulative value from the smaller particle size in a particle size distribution curve measured using a laser diffraction / scattering particle size analyzer “MT3200II” (trade name) manufactured by Nikkiso Co., Ltd. Is a particle size of 50% by mass.

Moreover, since the said active energy ray curable resin composition is diluted to the density | concentration which is easy to apply, it may contain the solvent as needed. The solvent is not particularly limited as long as it does not react with the components of the curable resin composition and other optional components or does not catalyze (promote) the self-reaction (including deterioration reaction) of these components. For example, known materials such as 1-methoxy-2-propanol, n-butyl acetate, toluene, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, and diacetone alcohol can be used.
Although these solvents are originally non-dominating factor components, they are usually used in large quantities, so by setting the same wet thickness and the same post-curing thickness, the curling force of the first hard coat layer can be increased. Since it is necessary to make the curl force of the second hard coat layer the same, it is preferable to treat it as a dominant factor component.

The active energy ray-curable resin composition can be obtained by mixing and stirring these components.

The thickness of the hard coat layer after curing is preferably 0.5 μm or more. If it is thinner than this, the effect of improving the scratch resistance may not be obtained. More preferably, it is 10 micrometers or more, More preferably, it is 15 micrometers or more. On the other hand, there is no particular upper limit for the thickness of the hard coat layer after curing. However, since an unnecessarily thick hard coat layer only increases the cost, the thickness is 60 μm at most.

The method for applying the paint is not particularly limited, and a known web application method can be used. Specifically, methods such as roll coating, gravure coating, reverse coating, roll brushing, spray coating, air knife coating, and die coating can be used.

The said transparent resin film is a film used as the base material of a glass alternative display face plate, and high transparency is required, and what is excellent also in rigidity and surface hardness is preferable. Moreover, the thing without curl is preferable.

Examples of such transparent resin films include thermoplastic resins such as acrylic resins, aromatic polycarbonate resins, polyamide resins, polyester resins, polyarylate resins, polymer-type urethane acrylate resins, and polyimide resins. Examples of the film include non-stretched film, uniaxially stretched film, and biaxially stretched film.

The thickness of the transparent resin film is usually 50 to 1000 μm. If it is thinner than this, the rigidity tends to be insufficient. If it is thicker than this, it will be difficult to meet the demand for thinner displays. Preferably it is 100-500 micrometers, More preferably, it is 200-300 micrometers.

Examples of the acrylic resin film include, for example, poly (meth) methyl acrylate, poly (meth) ethyl acrylate, poly (meth) acrylate propyl, poly (meth) acrylate butyl, methyl (meth) acrylate, ( (Meth) acrylic acid butyl copolymer, (meth) acrylic acid ethyl ester, (meth) acrylic acid butyl copolymer, etc .; (meth) acrylic acid ester; ethylene (meth) methyl acrylate copolymer, styrene (meta) 1) A copolymer containing (meth) acrylic acid ester such as methyl acrylate copolymer; 1 type or a mixture of two or more types of acrylic resin (A1-1) and methacrylic acid ester / styrene / butadiene rubber Graft copolymer, acrylonitrile / styrene / butadiene rubber graft copolymer, acrylonitrile / styrene / Tylene / propylene rubber graft copolymer, acrylonitrile / styrene / acrylate ester graft copolymer, methacrylate ester / acrylate ester rubber graft copolymer, methacrylate ester / acrylonitrile / acrylate ester rubber graft copolymer, etc. Examples thereof include an unstretched film, a uniaxially stretched film, and a biaxially stretched film made of an acrylic resin composition containing one or a mixture of two or more kinds of core-shell rubber (A1-2). In addition, (meth) acryl means acryl or methacryl.

The blending ratio of (A1-1) and (A1-2) is preferably (A1-1) 30 to 100 parts by mass, (A1-2) 30 to 30 parts when the total of both is 100 parts by mass. 0 parts by mass, more preferably (A1-1) 90-100 parts by mass and (A1-2) 10-0 parts by mass.

Further, optional components that can be included in the acrylic resin composition include thermoplastic resins other than acrylic resins and core-shell rubbers; pigments, inorganic fillers, organic fillers, resin fillers; lubricants, antioxidants, weathering stabilizers, heat And additives such as stabilizers, release agents, antistatic agents, and surfactants. The amount of these optional components is usually about 0.1 to 10 parts by mass when the total of (A1-1) and (A1-2) is 100 parts by mass.

Examples of the aromatic polycarbonate resin film include a polymer obtained by an interfacial polymerization method of an aromatic dihydroxy compound such as bisphenol A and phosgene; an aromatic dihydroxy compound such as bisphenol A and a carbonic diester such as diphenyl carbonate. A polymer obtained by transesterification; a mixture of one or more aromatic polycarbonate resins (A2-1) such as methacrylate ester / styrene / butadiene rubber graft copolymer, acrylonitrile / styrene / butadiene Rubber graft copolymer, acrylonitrile / styrene / ethylene / propylene rubber graft copolymer, acrylonitrile / styrene / acrylic ester graft copolymer, methacrylate / acrylic ester rubber And an aromatic polycarbonate-based resin composition comprising one or a mixture of two or more core-shell rubbers (A2-2) such as a copolymer, a methacrylic acid ester / acrylonitrile / acrylic acid ester rubber graft copolymer, etc. A stretched film, a uniaxially stretched film, and a biaxially stretched film can be mentioned.

The blending ratio of the above (A2-1) and the above (A2-2) is preferably (A1-1) 30 to 100 parts by mass, (A1-2) 30 to 30 when the total of both is 100 parts by mass. 0 parts by mass, more preferably (A1-1) 90-100 parts by mass and (A1-2) 10-0 parts by mass.

The optional components that can be included in the aromatic polycarbonate resin composition include thermoplastic resins other than aromatic polycarbonate resins and core-shell rubbers; pigments, inorganic fillers, organic fillers, resin fillers; lubricants, antioxidants, and weather resistance. And additives such as stabilizers, heat stabilizers, mold release agents, antistatic agents, and surfactants. The amount of these optional components is usually about 0.1 to 10 parts by mass when the total of (A2-1) and (A2-2) is 100 parts by mass.

A more preferable transparent resin film is a multilayer film having a first acrylic resin layer, an aromatic polycarbonate resin layer, and a second acrylic resin layer in order from the surface side, wherein the first acrylic resin layer and the first acrylic resin layer A multilayer film characterized in that the two acrylic resin layers are made of an acrylic resin having the same composition and have the same layer thickness. Here, the acrylic resin means one or a mixture of two or more of (A1-1) and a resin composition thereof. Preferably, it is a resin composition as described in said paragraph 0041-0043. Here, the aromatic polycarbonate-based resin means one or a mixture of two or more of (A2-1) and a resin composition thereof. Preferably, it is a resin composition as described in said paragraphs 0044-0046.

Acrylic resin films have excellent surface hardness but have weak impact resistance, whereas aromatic polycarbonate resin films have excellent impact resistance but have weak surface hardness. Therefore, by using the above-mentioned layer structure, the weak points of both are compensated, and a transparent laminated resin film excellent in both surface hardness and impact resistance is obtained.

In addition, in the laminated film which consists of a hard-coat layer and a base film layer, it is common knowledge of those skilled in the art that the surface hardness of a base film has big influence on the surface hardness by the side of the hard-coat layer of a laminated film. (For example, refer to paragraphs 0005 and 0006 of JP2007-084655A.)

The first acrylic resin layer and the second acrylic resin layer are made of an acrylic resin having the same composition and have the same layer thickness so that the transparent resin film itself does not curl. Because.

Here, “the same layer thickness” should not be interpreted as the same thickness in a strict physicochemical sense. It should be construed as the same layer thickness within the range of the process / quality control that is usually carried out industrially. This is because the object of the present application can be achieved as long as the layer thickness is the same within the range of the amplitude of the process and quality control that are usually performed industrially. For example, in the case of a non-stretched film by a coextrusion method, since the process and quality control are usually performed with a width of about -5 to +5 μm, the layer thickness 65 μm and the same 75 μm should be interpreted as the same. .

The “same composition” should not be construed as the same composition in a physicochemically strict sense. It should be construed as the same within the range of quality control that is usually performed industrially. For example, each raw material of acrylic resin, for example, the acrylic resin (A1-1), core-shell rubber (A1-2), and optional components, each using the same grade and manufactured according to the same recipe When a 1st acrylic resin layer and a 2nd acrylic resin layer are formed into a film using a resin, it should be interpreted as the same composition.

In addition, the polymer material may cause curling or non-curling of the film formed by forming the film depending on the film forming method and film forming conditions. Therefore, the first acrylic resin layer and the second acrylic type are used. The resin layer is preferably formed by the same film forming method under the same film forming conditions. Specifically, the T-die coextrusion method is preferable.

More preferably, the same layer thickness of the first acrylic resin layer and the second acrylic resin layer is 60 μm or more. By setting the thickness to 60 μm or more, a pencil hardness of 7H or more can be obtained.

EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to this.

Measurement method (a) Curling resistance film Samples of 10 cm in length and 10 cm in width were collected from a total of 15 locations at 5 locations every 50 m in the direction of the film MD at 3 locations in the center, left end, and right end in the CD direction. . The curled height at the four corners when the collected sample was placed on a horizontal surface was measured. The worst of all 15 samples (large curl height) was determined according to the following criteria.
A: Curl height is less than 5 mm B: Curl height is 5 mm or more and less than 10 mm Δ: Curl height is 10 mm or more and less than 25 mm x: Curl height is 25 mm or more

(B) Total light transmittance Measured according to JIS K 7361-1: 1997 using a turbidimeter “NDH2000” (trade name) manufactured by Nippon Denshoku Industries Co., Ltd.

(C) Haze Measured according to JIS K 7136: 2000 using a turbidimeter “NDH2000” (trade name) manufactured by Nippon Denshoku Industries Co., Ltd.

(D) Pencil Hardness According to JIS K 5600-5-4, the hardness of the surface of the first hard coat layer was evaluated using a pencil “Uni” (trade name) manufactured by Mitsubishi Pencil Co., Ltd. under a load of 200 g.

(E) Scratch resistance A sample having a length of 200 mm and a width of 25 mm was collected and placed on a JIS L 0849 Gakushin Tester so that the first hard coat layer was on the surface. Subsequently, after # 0000 steel wool was attached to the friction terminal of the Gakushin Tester, a 250 g load (1 cm × 1 cm) was placed, and the surface of the test piece was rubbed 10 times. The surface was visually observed and evaluated according to the following criteria.
◎: 0 to 5 scratches ○: 6 to 10 scratches ×: 11 or more scratches

Raw materials used (Pa) Dipentaerythritol hexaacrylate:
Nippon Kayaku Co., Ltd., 6-functional acrylic UV curable resin, solid content 100%
(Pb) Urethane acrylate:
“UM-901M” (trade name) manufactured by Negami Kogyo Co., Ltd., mass average molecular weight 3600, number of functional groups 9
(Pc) Modified silica dispersion:
After dropwise addition of 20.6 parts by mass of isophorone diisocyanate at 50 ° C. over 1 hour to a solution consisting of 7.8 parts by mass of mercaptopropyltrimethoxysilane and 0.2 parts by mass of dibutyltin dilaurate in dry air. , And stirred at 60 ° C. for 3 hours. 71.4 parts by mass of pentaerythritol triacrylate was added dropwise thereto at 30 ° C. over 1 hour, and the mixture was heated and stirred at 60 ° C. for 3 hours to obtain a silane compound as an alkoxysilane compound. This was designated as Silane Compound A. Analysis of the amount of residual isocyanate in the product was 0.1% or less, indicating that the reaction was almost quantitatively completed. Subsequently, 8.1 parts by mass of the silane compound A, colloidal silica methyl ethyl ketone dispersion (average particle size 10 to 20 nm, silica concentration 30%) “Methanol silica sol MEK-ST” (trade name) 90 manufactured by Nissan Chemical Co., Ltd. After stirring a liquid mixture of 0.5 parts by mass and 0.1 parts by mass of ion-exchanged water at 60 ° C. for 3 hours, 1.3 parts by mass of orthoformate methyl ester was added, and further heated and stirred at the same temperature for 1 hour. A colorless and transparent dispersion was obtained. This was used as a modified silica dispersion.
(Pd) Photopolymerization initiator:
"Irgacure 127" (trade name) manufactured by Ciba Specialty Chemicals
(Pe) Solvent:
50:50 (mass ratio) mixed solvent of methyl ethyl ketone and propylene glycol monomethyl ether

(Q) A multilayer film having a first acrylic resin layer, an aromatic polycarbonate resin layer, and a second acrylic resin layer in order from the surface of the transparent resin film, the first acrylic resin layer and the second acrylic resin A T-die coextruded film having a total thickness of 250 μm, wherein the resin layer is made of an acrylic resin having the same composition and has the same layer thickness of 70 μm.

Example 1

Preparation of intermediate paint:
60 parts by mass of the raw material (Pa), (Pb) 40 parts by mass, (Pc) 286 parts by mass (100 parts by mass as a solid content), (Pd) 7 parts by mass, (Pe) 120 parts by mass, An intermediate paint was obtained.

Preparation of paint for forming first hard coat layer (P1):
With respect to a total of 100 parts by mass of the intermediate paint component (Pa) and the component (Pb), the intermediate paint obtained above and the fluorine-based contamination inhibitor “RS-75 (trade name) of DIC Corporation” The mixture was mixed and stirred at a mixing ratio of 0.5 parts by mass of the contamination inhibitor to obtain a first hard coat layer-forming coating material (P1).

Preparation of paint for forming second hard coat layer (P2):
The intermediate paint obtained above was used as the second hard coat layer forming paint (P2) as it was.

Using a coating apparatus having two gravure-type coating parts, the paint (P1) was applied to one surface of the film (Q) so as to have a wet thickness of 35 μm in the first coating part, and then the film (Q ) Was turned upside down and conveyed to the second coating part, and the coating material (P2) was applied to the other surface of the film (Q) so as to have a wet thickness of 35 μm in the second coating part. In any coating part, the wet thickness was monitored by an on-line thickness meter of the coating apparatus, and the coating conditions were appropriately adjusted so as to be a predetermined wet thickness of −1 to +1 μm.

Subsequently, after pre-drying at 80 ° C., using the same high pressure mercury lamp type ultraviolet irradiation device from the top and bottom of the web and irradiating with ultraviolet rays in the same pattern, both are wet so that the thickness after curing is 17 μm. The coating film was cured to form a first hard coat layer and a second hard coat layer. In addition, the thickness after hardening of any hard-coat layer was monitored with the on-line thickness meter, and hardening conditions were adjusted suitably so that it might become predetermined thickness -0.5- + 0.5 micrometer after hardening.

The obtained transparent resin laminated film was subjected to the above tests (a) to (e). The results are shown in Table 1.

Example 2
Except that the predetermined wet thickness was changed to 60 μm and the predetermined post-curing thickness was changed to 30 μm, all operations were performed in the same manner as in Example 1. The results are shown in Table 1.

Example 3
All operations were performed in the same manner as in Example 1 except that the wet thickness management width was changed to −2 to +2 μm and the post-curing thickness management width was changed to −1 to +1 μm. The results are shown in Table 1.

Comparative Example 1
All operations were performed in the same manner as in Example 1, except that the wet thickness management width was changed to −6 to +6 μm, and the post-curing thickness management width was changed to −3 to +3 μm. The results are shown in Table 1.

Comparative Example 2
Except for using a paint using ditrimethylolpropane tetraacrylate (manufactured by Nippon Kayaku Co., Ltd., tetrafunctional acrylic UV curable resin, solid content 100%) as the paint (P2) instead of the component (Pa) All were performed in the same manner as in Example 1. The results are shown in Table 1.

The laminated films obtained in Examples 1 to 3 which are the production methods of the present invention are excellent in transparency, surface hardness and scratch resistance, and curling is suppressed. The sample with the highest curl height in Example 1 had a thickness after curing of the first hard coat layer of 17.3 μm and a thickness after curing of the second hard coat layer of 16.6 μm. Example 2 was 29.7 micrometers and 30.5 micrometers in order. Example 3 was 16.1 μm and 17.8 μm in this order.

On the other hand, Comparative Example 1 is too wide in manufacturing control and deviates from the requirement of the present invention that “the same wet thickness is applied and then the cured thickness is the same”. Therefore, the curl resistance is insufficient. The sample with the highest curl height in Comparative Example 1 had a thickness after curing of the first hard coat layer of 14.1 μm and a thickness of cured second hard coat layer of 19.6 μm.

In Comparative Example 2, the curable resin of the controlling factor component is different between the paint (P1) and the paint (P2), which is outside the requirement of “the same potential for generating curling force” of the present invention. The curl resistance is poor. The sample with the highest curl height in Comparative Example 2 had a thickness after curing of the first hard coat layer of 16.7 μm and a thickness after curing of the second hard coat layer of 17.3 μm.

Claims (4)

A method for producing a transparent resin laminated film,
(1) The transparent resin laminated film has a first hard coat layer, a transparent resin film layer, and a second hard coat layer in this order from the surface side.
(2) The first hard coat layer forming paint and the second hard coat layer forming paint have the same potential to generate a force to curl the transparent resin laminated film,
(3) After applying the first hard coat layer-forming paint on one surface of the transparent resin film and the second hard coat layer-forming paint on the other surface so as to have the same wet thickness, A method comprising curing the hard coat layer and the second hard coat layer so as to have the same thickness after curing.
The transparent resin film is a multilayer film having a first acrylic resin layer, an aromatic polycarbonate resin layer, and a second acrylic resin layer in order from the surface side,
The first acrylic resin layer and the second acrylic resin layer are multilayer films characterized by being made of an acrylic resin having the same composition and having the same layer thickness. The method of claim 1.
The method according to claim 2, wherein the same thickness of the first acrylic resin layer and the second acrylic resin layer is 60 µm or more.
The transparent resin laminated film manufactured by the method of any one of Claims 1-3.