JP2020042199A - Antireflection hard coat film for molding - Google Patents

Abstract

To provide an antireflection hard coat film for molding which is an optical film for molding that has low reflectivity and is excellent in elongation property, and is suitable for three-dimensional molding such as insert molding, as a decoration for vehicle interior such as an electronic apparatus and an automobile.SOLUTION: An antireflection hard coat film for molding has a hard coat resin layer on one surface of a thermoplastic transparent base material film and has a low refractive index layer on the hard coat layer surface, in which the hard coat resin layer contains polyfunctional urethane (meth)acrylate oligomer (A) having a skeleton obtained by reaction of low-molecular-weight polyol and polyisocyanate, (meth)acrylate (B) having a fluorene skeleton, and a photopolymerization initiator (C).SELECTED DRAWING: None

Description

The present invention relates to an antireflection hard coat film used for forming a film.

  Acrylic photocurable resins have been used in many fields to impart special properties to the surface of plastic films and molded plastics. For example, a hard coat film coated on a PET (polyethylene terephthalate) film to impart high hardness is used in large quantities as a film for a touch panel or a film for molding.

  Among these, especially for molding, an insert film that prints a picture on a film surface and then performs three-dimensional molding in a state of being softened by heating is well known, and is widely used for a cover of a display. Recently, it has been required to prevent reflection of external light in order to improve visibility, particularly when used in displays in the field of vehicles.

  To meet such demands, for example, urethane acrylate oligomers having 6 or more (meth) acryloyl groups and / or polyfunctional (meth) acrylates or oligomers having 3 or more (meth) acryloyl groups, hollow silica, An antireflection film for molding coated with an ultraviolet curable resin comprising an initiator has been proposed. However, when the resin is used to provide an anti-reflection function, the thickness of the resin layer is 1 μm or less due to the relationship of the reflectance, so that the hard coat performance is insufficient. Film was required.

JP 2017-171715 A

The present invention is an optical film for molding excellent in extensibility with low reflectivity, and for decoration of a vehicle interior such as an electronic device or an automobile, which is suitable for three-dimensional molding such as insert molding. It is to provide a coat film.

The invention according to claim 1 has a hard coat resin layer on one surface of a thermoplastic transparent base film, a low refractive index layer on the hard coat resin layer surface, and the hard coat resin layer has a low molecular weight. A polyfunctional urethane (meth) acrylate oligomer (A) having a skeleton obtained by reacting a polyol and a polyisocyanate, a (meth) acrylate (B) having a fluorene skeleton, and a photopolymerization initiator (C). An antireflection hard coat film for molding is provided.

The antireflection hard coat for molding according to claim 1, wherein the low molecular weight polyol forming the skeleton of the polyfunctional urethane (meth) acrylate oligomer (A) is ethylene glycol. Provide a film.

  The invention according to claim 3, wherein the polyfunctional urethane (meth) acrylate oligomer (A) has a weight average molecular weight of 2,000 to 30,000, and the antireflection hardening mold according to claim 1 or 2. Provide a coated film.

  The invention according to claim 4 is characterized in that the blending amount of the (meth) acrylate (B) having a fluorene skeleton is 35 to 80% by weight based on the total solid content. The present invention provides an antireflective hard coat film for molding.

The invention according to claim 5 provides an antireflection hard coat film for molding according to any one of claims 1 to 4, which is for insert molding.

The hard coat film of the present invention has low reflectivity and excellent extensibility, and is used as a decoration anti-reflection hard coat film suitable for three-dimensional molding such as insert molding, for decoration of vehicle interiors such as electronic devices and automobiles. Useful.

  Hereinafter, the present invention will be described in detail.

The composition of the composition of the present invention comprises a polyfunctional urethane (meth) acrylate oligomer (A), a (meth) acrylate (B) having a fluorene skeleton, and a photopolymerization initiator (C). In this specification, (meth) acrylate includes both acrylate and methacrylate.

The polyfunctional urethane (meth) acrylate oligomer (A) used in the present invention is produced, for example, by reacting both ends of a compound obtained by reacting a low molecular weight polyol with a polyisocyanate with hydroxy (meth) acrylate, This is a structure having two or more (meth) acryloyl groups and a urethane bond in one molecule. The number of functional groups is preferably 4 or more, more preferably 6 or more, from the balance between reactivity and optical properties. If the number of functional groups is one, the reactivity at the time of polymerization is low and the molecular weight does not increase, which is unsuitable. If the number of functional groups is four or more, the reaction is performed without using a monomer other than the (meth) acrylate (B) having a fluorene skeleton. This is preferable because the refractive index can be increased because the refractive index can be ensured.

Examples of the low molecular weight polyol used in (A) include ethylene glycol, propylene glycol, diethylene glycol, butanediol, cyclohexanediol, and the like, and these can be used alone or in combination of two or more. Among these, ethylene glycol having the smallest carbon number of the alkyl group is preferable because the urethane bond concentration in the oligomer can be increased. By increasing the concentration of urethane bonds, a tough cured film can be formed. Even with the same ethylene glycol type, it is impossible to use polyethylene glycol which is a polyether skeleton because the urethane bond concentration is low and the chemical resistance is poor.

Examples of the polyisocyanate used in the above (A) include hexamethylene diisocyanate (hereinafter HDI), isophorone diisocyanate (hereinafter IPDI), diphenylmethane diisocyanate, tolylene diisocyanate, dicyclohexylmethane-4,4′-diisocyanate, hydrogenated xylylene diisocyanate , Methylcyclohexylene diisocyanate, HDI isocyanurate, IPDI isocyanurate, etc., and these may be used alone or in combination of two or more. Among them, preferred are aliphatic and alicyclic diisocyanates which have low weather resistance and are not easily yellowed, and particularly preferred are IPDI having high bulk and high rigidity.

Examples of the hydroxy (meth) acrylate used in the above (A) include, for example, trimethylolpropane di (meth) acrylate, glycerin di (meth) acrylate, pentaerythritol di (meth) acrylate, diglycerin di (meth) acrylate, Methylolpropane di (meth) acrylate, dipentaerythritol di (meth) acrylate, etc., trifunctional or more diglycerin tri (meth) acrylate, ditrimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, dipenta There are erythritol tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, and dipentaerythritol penta (meth) acrylate. Among these, trifunctional or more functional groups (the number of functional groups of the synthesized (A) is equivalent to 6 or more functional groups) are preferable, and pentaerythritol triacrylate (hereinafter, PETA) having high curability is particularly preferable.

The weight average molecular weight (Mw) of (A) is preferably from 2,000 to 30,000, more preferably from 2,500 to 20,000, particularly preferably from 3,000 to 10,000. When it is 2,000 or more, sufficient strength and elongation as a cured film can be secured, and when it is 30,000 or less, it becomes easy to adjust the viscosity to an appropriate value as a coating agent. Mw was measured and calculated by gel permeation chromatography using a column using a filler based on styrenedivinylbenzene, using a tetrahydrofuran eluent as a standard polystyrene equivalent molecular weight.

The blending amount of (A) with respect to the total solid content is preferably 15 to 64% by weight, more preferably 18 to 60% by weight. When the content is 15% by weight or more, sufficient cohesive force and film strength can be secured, and when the content is 64% by weight or less, the viscosity of the composition can be appropriately controlled and good workability can be secured.

  The (meth) acrylate (B) having a fluorene skeleton used in the present invention is blended to increase the refractive index of the hard coat resin layer. In order to lower the reflectance of the antireflection film, it is effective to increase the refractive index difference from the low refractive index layer laminated on the hard coat resin layer. It is necessary to make it higher or lower the refractive index of the low refractive index layer. The refractive index (nD25, after curing) of (B) is about 1.5, which is about 1.6, while that of general (meth) acrylate is about 1.5, so that the refractive index of the hard coat resin layer is about 0.1. Can be higher.

The refractive index (nD25, after curing) of (B) is preferably from 1.555 to 1.675, more preferably from 1.600 to 1.655. By setting it in this range, there is an effect of increasing the refractive index of the hard coat resin layer, and it is possible to keep the reflectance low. The number of functional groups is preferably bifunctional so that the crosslink density that hinders the elongation of the cured film does not become high.

  The amount of (B) is preferably 35 to 80% by weight, more preferably 38 to 77% by weight, based on the total solid content. When the content is 35% by weight or more, the refractive index can be increased, and when the content is 80% by weight or less, a sufficient elongation can be secured. Further, in order to increase the refractive index, it is preferable that the monomer to be reacted with (A) is (B) alone. In that case, the number of functional groups in (A) is preferably 6 or more in order to increase the curing reactivity.

The photopolymerization initiator (C) used in the present invention generates radicals upon irradiation with ultraviolet rays or electron beams, and the radicals trigger the polymerization reaction. Benzyl ketals, acetophenones, and phosphine oxides are used. General-purpose photopolymerization initiators can be used. By arbitrarily selecting the light absorption wavelength of the polymerization initiator, curability can be imparted over a wide wavelength range from the ultraviolet region to the visible light region. Specifically, 2.2-dimethoxy-1.2-diphenylethan-1-one is used as a benzyl ketal type, and 1-hydroxy-cyclohexyl-phenyl-ketone and 1- [4- (2- Hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one is 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropane-1 as an α-aminoacetophenone system. -One is an acylphosphine oxide-based compound such as 2.4.6-trimethylbenzoyl-diphenyl-phosphine oxide and bis (2.4.6-trimethylbenzoyl) -phenylphosphine oxide. Can be used in combination. Among these, it is preferable to include an α-hydroxyacetophenone-based compound which is hardly yellowed, and examples of commercially available products include Irgacure 184 and Irgacure 2959 (trade name: manufactured by BASF Japan).

  The ratio of (C) to 100 parts by weight of the ultraviolet curable resin component is preferably 1 part by weight to 10 parts by weight, and more preferably 3 to 8 parts by weight. When the amount is 1 part by weight or more, sufficient curability is exhibited, and when the amount is 10 parts by weight or less, excessive addition is not caused, and yellowing of the coating film and deterioration in storage stability can be prevented.

The hard coat resin forming the hard coat layer of the present invention is diluted with a solvent to a solid content of 10 to 70% in order to improve coatability on the thermoplastic transparent substrate film. Examples of the solvent include alcohol solvents such as ethanol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, and diacetone alcohol; ketone solvents such as acetone, methyl ethyl ketone (hereinafter MEK), methyl isobutyl ketone, and cyclohexanone. , Methyl acetate, butyl acetate, ester solvents such as propylene glycol monomethyl ether acetate (hereinafter, PGMEA), and ether solvents such as propylene glycol monomethyl ether (hereinafter, PGM), diethyl ether, diisopropyl ether and the like. These can be used in combination. Among these, MEK, PGM, PGMEA, and the like having good compatibility with (A) and (B) are preferable.

In addition, the photocurable resin composition of the present invention may contain a reactive diluent, an antioxidant, an ultraviolet absorber, a (near) infrared absorber, a fluorescent whitening agent, if necessary, as long as the performance is not impaired. Sensitizers, flame retardants, fillers, organic fine particles, inorganic fine particles, dispersants, silane coupling agents, leveling agents, defoamers, surfactants, anti-fingerprint agents, antistatic agents, antibacterial agents, antiviral agents, Additives such as polymerization inhibitors, coloring agents such as pigments, dyes and dyes, and plasticizers can be used in combination.

The low refractive index layer provided on the hard coat layer surface of the present invention may be a vapor-deposited film such as a silicon oxide film or a wet coating film. Coatings are preferred. In this case, the binder resin is preferably an acrylic resin having good adhesion to the hard coat layer, and examples of the raw material to be mixed for lowering the refractive index include hollow silica and a fluorine compound. . As a commercially available coating agent, there is Z-825-12L (IPA) (trade name: manufactured by Aika Kogyo KK, acrylic resin, refractive index: 1.35).

  As the thermoplastic transparent base film to which the hard coat resin of the present invention is applied, a polyethylene terephthalate (PET) film, a polyethylene naphthalate film, a polyvinyl chloride film, a polystyrene film, an acrylic film, a polycarbonate film, a cycloolefin (CO) Examples thereof include polymer films, polyimide films, polyolefin films (PP, PE, etc.) and composite films thereof. Among these, a PET film that has been biaxially stretched in terms of price, processability, dimensional stability, and the like, and an acrylic film, a polycarbonate film, or a laminated film thereof are preferably used in terms of weather resistance.

For the purpose of improving the adhesiveness with the hard coat resin, the thermoplastic transparent base film is treated with a primer, a corona, a sand blast method, a surface treatment with a solvent treatment or the like, a chromic acid treatment, an ozone treatment. A surface treatment such as an oxidation treatment of the surface such as an ultraviolet irradiation treatment can be performed.

Examples of the method of applying the hard coat resin of the present invention to a thermoplastic transparent base film include a bar coater method, an applicator method, a curtain coater method, a roll coater method, a gravure coater method, a reverse coater method, a comma coater method, and a lip coater method. A known method such as a die coater method can be applied. The applied film thickness is typically 1 to 20 μm as a dry film thickness, but is not particularly specified and can be selected as needed.

After applying the hard coat resin, it is dried at 60 to 120 ° C. to evaporate the solvent, and is cured using an ultraviolet irradiator. The ultraviolet irradiation ^conditions, the irradiation intensity of ^{500mW / cm 2 ~3,000mW / cm 2} , 100mJ / cm 2 ~2,000mJ / cm 2 can be exemplified as the cumulative amount of light. Known light sources such as a high-pressure mercury lamp, a medium-pressure mercury lamp, a low-pressure mercury lamp, a metal halide lamp, a xenon lamp, an LED lamp, and an electrodeless ultraviolet lamp can be used as the light source.

The thickness of the molded sheet is appropriately determined depending on the application. However, if the thickness is too small, the strength is insufficient, and if the thickness is too large, the moldability is reduced. For example, the thickness is 50 μm to 300 μm. There is no problem. Further, a coating film that imparts another function may be formed on the surface of a molded sheet using the photocurable resin composition, or a composite sheet in which other materials are further laminated may be used. When a PET film substrate having a sheet thickness of 125 μm is used, if the elongation percentage at an ambient temperature of 130 ° C. is 50% or more, moldability as a molded sheet for decorative use can be ensured.

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples, but it shows specific examples and does not particularly limit the present invention. In addition, when there is no description, the measurement was performed under the condition of room temperature of 25 ° C. and relative humidity of 65%. In addition, the compounding amount shows a weight part.

Synthesis of urethane acrylate (hereinafter Urech) A 200 parts by weight of ethylene glycol (hereinafter EG) and 778 parts by weight of IPDI (trade name : Desmodur I manufactured by Sumika Bayer Urethane Co., Ltd., 37.5% of NCO group) are MEK. The mixture was added to a solvent (solid content: 60%), stirred and reacted at 30 ° C. for 30 minutes, and the reaction was terminated when the peak of the isocyanate group reached a predetermined amount by infrared absorption analysis. Next, 150 parts by weight of PETA (trade name: PET30, 100% solid content, manufactured by Nippon Kayaku Co., Ltd.) was added, and the mixture was stirred and reacted at 10 ° C. for 30 minutes. Analysis confirmed that the isocyanate group had disappeared, and adjusted the solid content to 60% with MEK. 4,200 hexafunctional ureacs A were obtained.

Synthesis of ureac B 200 parts by weight of ethylene glycol (hereinafter referred to as EG) and 892 parts by weight of IPDI (trade name: Desmodur I, 37.5% NCO group, manufactured by Sumika Bayer Urethane Co., Ltd.) in MEK solvent (solid content) 40%), and the mixture was stirred and reacted at 30 ° C. for 30 minutes. The reaction was terminated when the peak of the isocyanate group reached a predetermined amount in infrared absorption analysis. Next, 150 parts by weight of PETA (trade name: PET30, 100% solid content, manufactured by Nippon Kayaku Co., Ltd.) was added, and the mixture was stirred and reacted at 10 ° C. for 30 minutes. The analysis confirmed that the isocyanate group had disappeared, and the solid content was adjusted to 40% by PGM. 8,000 hexafunctional ureac B were obtained.

Hard coat resin composition 1-8
Urea A and B as (A), OGSOL EA-025P (trade name, manufactured by Osaka Gas Chemical Co., difunctional, refractive index 1.626, PGMEA 50% dilution) as (B), and Irgacure 2959 (product as (C)) Name: BASF Japan Co., Ltd., and ureac C (reacting IPTA with PETA, Mw 1,400, 6-functional) and D (reacting HDI with PETA, Mw 800, 6-functional) and DPHA (dipentaerythritol hexaacrylate) Was diluted with PGM so as to have a solid content of 30% in the composition shown in Table 1 and stirred until it was uniformly dissolved to prepare a hard coat resin composition of compositions 1 to 8 (hereinafter referred to as a resin composition).

Test film A
The hard coat resin compositions 1 to 8 are coated on a PET film 125U403 (trade name: manufactured by Toray Industries, Inc., thickness: 125 μm) so as to have a dry film thickness of 3 μm, and dried at 80 ° C. for 1 minute in a constant temperature bath. Thereafter, a test film A was prepared by irradiating ultraviolet rays with an electrodeless lamp so that the output was 1,000 mW / cm 2 and the integrated light amount was 150 mJ.

Test film B
On the resin composition layer of the test film A, Z-825-12L (IPA) (trade name: manufactured by Aika Kogyo Co., Ltd.) is applied as a low refractive index layer so as to have a film thickness of 100 nm after drying, and is kept at a constant temperature. After drying in a bath at 80 ° C. for 1 minute, a test film B was prepared by irradiating ultraviolet rays under an atmosphere of nitrogen with an electrodeless lamp so that the output was 1,000 mW / cm 2 and the integrated light amount was 150 mJ.

Table 1

The evaluation method was as follows.

Total light transmittance: Test films A and B were measured using a haze meter-Haze-gard 2 manufactured by Toyo Seiki Seisakusho in accordance with JIS K7361-1. In the case of film B, 93% or more was evaluated as ○, and less than 93% was evaluated as ×.

Elongation: The test film A was cut into 25 mm x 50 mm, and a tensile test was conducted using a Minebea tensile tester TGI-1 kN at an ambient temperature of 130 ° C and a crosshead speed of 300 mm / min. The percentage was 50% or more, and ○ was less than 50%.
Calculation formula: Calculated based on how many mm elongate based on 50 mm.
Elongation rate (%) = Elongated length (mm) / 50 mm × 100

Refractive index: A curable resin composition was applied to a PET film 125U403 (trade name: 125 μm, manufactured by Toray Industries, Inc.) with a bar coater to a thickness of 5 μm to obtain a test film. The refractive index at a D line of 589 nm was measured using an Atago Co. refractometer DR-M2. The test film was set on the prism surface, and 1-bromonaphthalene was used as the intermediate solution.

  Minimum reflectance: Using test films A and B, apply a uniform scratch to the surface opposite to the coated surface with sandpaper, paint it with a black pigment marker, and then apply a black PET film on the opposite side. The reflectance of the surface is set to 0%. Using a spectrophotometer V650 manufactured by JASCO Corporation, the reflectance is plotted every 1 nm in the range of 380 to 780 nm, and the smallest reflectance is measured. Is indicated by x.

Evaluation results Table 2

Each of the resin compositions of Examples obtained good results in the evaluation items of total light transmittance, elongation, and minimum reflectance.

On the other hand, Comparative Example 1 in which (B) was not blended had a large minimum reflectance, and Comparative Examples 2 and 3 using hexafunctional ureacs other than (A), and Comparative Example 4 using hexafunctional acrylate, showed an elongation percentage. And all were not suitable for the present invention.

The invention of the present application is an optical film for molding excellent in extensibility with low reflectivity, and used as a decoration anti-reflection hard suitable for three-dimensional molding such as insert molding for decorating a vehicle interior such as an electronic device or an automobile. Useful as a coat film.

Claims (5)

  Having a hard coat resin layer on one surface of the thermoplastic transparent substrate film, having a low refractive index layer on the hard coat resin layer surface, the hard coat resin layer reacted a low molecular weight polyol and polyisocyanate An antireflection hard for molding, comprising: a polyfunctional urethane (meth) acrylate oligomer (A) having a skeleton; a (meth) acrylate (B) having a fluorene skeleton; and a photopolymerization initiator (C). Coat film.   The antireflection hard coat film for molding according to claim 1, wherein the low molecular weight polyol forming the skeleton of the polyfunctional urethane (meth) acrylate oligomer (A) is ethylene glycol. The antireflection hard coat film for molding according to claim 1, wherein the polyfunctional urethane (meth) acrylate oligomer (A) has a weight average molecular weight of 2,000 to 30,000.   The antireflection hard coat film for molding according to any one of claims 1 to 3, wherein the compounding amount of the (meth) acrylate (B) having a fluorene skeleton is 35 to 80% by weight based on the total solid content. . The antireflection hard coat film for molding according to any one of claims 1 to 4, which is for insert molding.