JP7441102B2 - Resin film and light diffusion film - Google Patents

Description

The present invention relates to a resin film and a light diffusion film.

In recent years, the number of illuminated signboards that use LEDs as internal light sources has increased, and in order to diffuse the linear light of the LEDs and make it difficult to see the internal light sources from the outside, thermoplastic resin films with light blocking properties are used. has been done.

Thermoplastic resin films are transparent to light and are used as display layers of illuminated signboards that have electric lights such as LEDs inside.

For example, Patent Document 1 describes a light diffusing sheet containing a transparent resin, a light diffusing agent that is a spherical body containing a crosslinked melamine resin, and 2-ethylhexyl-2-cyano-3,3-diphenylacrylate. There is.

Japanese Patent Application Publication No. 2011-175227 (published on September 8, 2011)

For example, unlike the resin film described in Patent Document 1, a resin film formed from a thermoplastic resin containing inorganic particles is a light-diffusing film from the viewpoint that the inorganic particles have high stability against heat and light. expected to be used in However, films made of thermoplastic resins containing inorganic particles have a problem of insufficient light diffusivity. Furthermore, when the content of inorganic particles is increased in order to improve light diffusivity, there is also the problem that the film becomes brittle and difficult to handle.

The present invention has been made in view of the above problems, and its purpose is to provide a novel resin film with high light diffusivity and low brittleness, and its related technology.

In order to solve the above problems, a resin film according to one embodiment of the present invention contains a first thermoplastic resin, a second thermoplastic resin, and inorganic particles, and contains 100 parts by mass of the first thermoplastic resin. The content of the second thermoplastic resin relative to the resin is 5 parts by mass or more, and the content of the inorganic particles relative to 100 parts by mass of the first thermoplastic resin is 10 parts by mass or more and 60 parts by mass or less. .

Advantageous Effects of Invention According to the present invention, it is possible to provide a novel resin film with high light diffusivity and low brittleness, and techniques related thereto.

1 is a diagram schematically explaining a resin film 1 according to one embodiment of the present invention. 1 is a diagram schematically explaining a light diffusion film 10 including a resin film 1 according to one embodiment of the present invention. FIG. 1 is a diagram schematically explaining a light diffusion film 11 including a resin film 1 according to one embodiment of the present invention. It is a figure explaining the outline of use of light diffusion film 11 concerning one aspect of the present invention.

In this specification, a numerical range indicated using "-" indicates a range that includes the numerical values written before and after "-" as the minimum and maximum values, respectively.

Hereinafter, one embodiment of the present invention will be described in detail.
<Resin film>
A resin film 1 according to one embodiment of the present invention shown in FIG. 1 is formed from a resin composition containing a first thermoplastic resin, a second thermoplastic resin, and inorganic particles. Furthermore, the resin film according to one embodiment may contain other additives.

It is preferable that the resin film 1 has a haze of 70% or more and 98% or less. If the haze is 70% or more, high light diffusivity can be imparted to the resin film. Light diffusibility refers to the diffusibility of light that is irradiated onto a resin film from a light source and transmitted through the resin film. Further, if the haze is 98% or less, it is possible to prevent the brightness of the light emitted from the light source, transmitted through the resin film, and illuminated from the surface of the resin film from decreasing excessively. Therefore, the resin film 1 according to one embodiment can be suitably used as a display layer of an internally illuminated signboard, for example.

Furthermore, the elongation at break of the resin film 1 is preferably 20% or more, more preferably 50% or more. In addition, when the resin film has a breaking elongation of 20% or more, it is possible to suitably prevent breakage when handling the resin film for use as a display layer having a large area, and from breakage after pasting. Note that the method for measuring the elongation at break is explained in detail in the Examples section.

The resin film 1 preferably has a thickness of 20 to 100 μm, more preferably 30 to 60 μm. The resin film according to one embodiment of the present invention has a thin resin film having a thickness of 20 to 100 μm by containing 15 parts by mass or more and 50 parts by mass of inorganic particles based on 100 parts by mass of the first thermoplastic resin described below. Even when formed into a film, it has a high haze of 70% or more and 98% or less, and has a high elongation at break.

In the resin film according to one aspect of the present invention, the content of the inorganic particles is 10 parts by mass or more and 60 parts by mass or less with respect to 100 parts by mass of the first thermoplastic resin, so that the printed layer can be formed as described below. The ink for forming can be applied uniformly.

[First thermoplastic resin]
The first thermoplastic resin contained in the resin film is the main resin component of the continuous phase containing inorganic particles as a dispersed phase.

The storage modulus of the first thermoplastic resin at 23°C is higher than that of the second thermoplastic resin at 23°C, and the storage modulus of the first thermoplastic resin at 23°C is 1000 to 2500 MPa. It is preferably 1,250 to 2,000 MPa, and more preferably 1,250 to 2,000 MPa. If the storage modulus of the first thermoplastic resin at room temperature (23° C.) is 1000 MPa or more, for example, the resin film will not soften excessively, and deformation when used as a display layer can be suitably prevented. Moreover, if the storage elastic modulus of the first thermoplastic resin at room temperature of 23° C. is 2500 Pa or less, it is possible to suitably prevent embrittlement of the resin film.

The conditions for measuring the storage modulus at 23°C of the first thermoplastic resin and the second thermoplastic resin described later are a temperature range of -60 to 200°C, a heating rate of 2°C/min, and a frequency of 1Hz. It may be determined based on the measurement results of the viscoelastic spectrum obtained by.

Selected from the group consisting of vinyl chloride resins, (meth)acrylic resins, polycarbonate resins, polystyrene resins, cyclic olefin resins, polyester resins, polyurethane resins, ABS resins, etc., having a storage modulus of 1000 to 2500 MPa at 23°C. It is preferable to select and use the first thermoplastic resin. Among these, from the viewpoint of outdoor weather resistance, the first thermoplastic resin is preferably a vinyl chloride resin or a (meth)acrylic resin, and since they have good moldability into a film, The plastic resin is more preferably a vinyl chloride resin. Note that the vinyl chloride resin may contain other monomer units, and may be, for example, a vinyl chloride-vinyl acetate copolymer.

[Second thermoplastic resin]
The resin film according to one embodiment of the present invention includes a second thermoplastic resin. In this embodiment, the second thermoplastic resin may be a thermoplastic resin whose content in the resin film is smaller than that of the first thermoplastic resin. In the resin film according to one embodiment of the present invention, the second thermoplastic resin is compatible with the first thermoplastic resin and can form a continuous phase in which inorganic particles are dispersed.

The storage modulus of the second thermoplastic resin at 23°C is preferably lower than the storage modulus of the first thermoplastic resin at 23°C. The storage modulus of the second thermoplastic resin at 23° C. is preferably 10 MPa or more, more preferably 20 MPa. Further, the storage modulus of the second thermoplastic resin at 23°C is preferably 2000 MPa or less, more preferably 1200 MPa or less, and even more preferably 600 MPa. If the storage modulus of the second thermoplastic resin at room temperature of 23°C is below the above upper limit, dispersing inorganic particles in the second thermoplastic resin in advance may cause dot dropouts in the resin film. Aggregates of the inorganic particles can be eliminated and the inorganic particles can be more uniformly dispersed. This improvement in dispersibility improves light diffusivity and improves the brittleness of the resin film. Moreover, if the storage elastic modulus of the second thermoplastic resin at room temperature of 23° C. is equal to or higher than the above lower limit value, for example, embrittlement of the resin film can be suitably prevented.

The second thermoplastic resin is a thermoplastic resin selected from the group consisting of polyurethane resin, (meth)acrylic resin, polyester resin, and ethylene-vinyl acetate resin, and has a storage modulus at 23°C within the above range. It is preferable to select and use it for the resin film. Among these, the second thermoplastic resin is preferably a polyurethane resin or a (meth)acrylic resin from the viewpoint of having high weather resistance and good compatibility with the first thermoplastic resin.

[Inorganic particles]
The resin film according to one embodiment of the present invention includes inorganic particles as light-diffusing particles. The inorganic particles are a dispersed phase dispersed within a continuous phase that includes first and second thermoplastic resins. The dispersed phase of inorganic particles contained in the resin film is preferably dispersed in the continuous phase as primary particles of the inorganic particles.

The refractive index of the inorganic particles is preferably 1.40 to 2.80, more preferably 1.4 to 1.70. By using inorganic particles with a refractive index of 1.40 to 2.80, high light diffusivity can be imparted to the resin film.

Further, the volume median diameter of the inorganic particles is preferably 1 μm to 10 μm, more preferably 1 μm or more and 5 μm or less. Since the parallel light transmittance of the light diffusive particles shows a minimum value, the shape of the light source is sufficiently visible through the film attached to the light source (adherent) through the adhesive layer formed from the adhesive composition. can be hidden. Note that the volume median diameter of the inorganic particles can be measured by a laser diffraction method.

Based on the above refractive index and volume median diameter, inorganic particles include, for example, calcium carbonate, silica, magnesium carbonate, talc, aluminum hydroxide, alumina, zirconia, titania, barium sulfate, and hydrotalcites. . Two or more types of these inorganic particles may be used in combination.

Further, the content of the inorganic particles with respect to 100 parts by mass of the first thermoplastic resin is preferably 10 parts by mass or more and 60 parts by mass or less. If the content of the inorganic particles is 10 parts by mass or more and 60 parts by mass or less with respect to 100 parts by mass of the first thermoplastic resin, a resin film with high haze and high elongation at break can be obtained. Moreover, a resin film having excellent printability with ink or the like on the surface can be suitably formed.

[Other additives]
The resin film according to one embodiment preferably contains a plasticizer, a stabilizer, and a lubricant as other additives.

[Plasticizer]
The resin film according to one embodiment preferably contains a plasticizer. Examples of plasticizers include polyester plasticizers, including phthalate plasticizers such as dioctyl terephthalate (DOP) and diisononyl terephthalate (DINP), and aromatic polyester plasticizers such as trimellitic acid ester plasticizers. Examples include plasticizers and fatty acid polyester plasticizers such as adipate esters. Among these, aliphatic polyester plasticizers having a number average molecular weight (Mn) of 1,000 to 10,000 are more preferred because they are less likely to bleed onto the surface of the resin film. Other plasticizers include paraffinic mineral oil softeners, liquid paraffin, polybutene, and the like. These plasticizers may be appropriately selected depending on the type of first thermoplastic resin.

The content of the plasticizer is preferably 10 to 50 parts by mass, more preferably 20 to 40 parts by mass, based on 100 parts by mass of the first thermoplastic resin.

[Stabilizer]
The resin composition according to one embodiment more preferably contains a stabilizer. Examples of the stabilizer include a heat stabilizer, a light stabilizer, and a stabilizing aid.

Further, examples of the heat stabilizer include phosphite compounds, hindered amine compounds, and perchlorate metal salts. Further, when the thermoplastic resin is a vinyl chloride resin, the heat stabilizer further includes a metal tin stabilizer and a metal salt of an organic acid.

For example, phosphite compounds include, for example, triphenyl phosphite, trisnonylphenyl phosphite, and 4,4'-isopropylidene-diphenol-alkyl phosphite, and perchlorate metal salts include, for example, , sodium perchlorate, barium perchlorate, and the like. In addition, examples of hindered amine compounds include 2,2,6,6-tetramethyl-4-piperidyl stearate, 1,2,2,6,6-pentamethyl-4-piperidyl stearate, 2,2,6 , 6-tetramethyl-4-piperidyl benzoate, bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, Tetrakis(2,2,6,6-tetramethyl-4-piperidyl)butanetetracarboxylate, Tetrakis(1,2,2,6,6-pentamethyl-4-piperidyl)butanetetracarboxylate, Bis(1,2 , 2,6,6-pentamethyl-4-piperidyl) di(tridecyl)-1,2,3,4-butanetetracarboxylate, 3,9-bis[1,1-dimethyl-2-{tris(2 ,2,6,6-tetramethyl-4-piperidyloxycarbonyloxy)butylcarbonyloxy}ethyl]-2,4,8,10-tetraoxaspiro[5.5]undecane, 3,9-bis[1, 1-dimethyl-2-{tris(1,2,2,6,6-pentamethyl-4-piperidyloxycarbonyloxy)butylcarbonyloxy}ethyl]-2,4,8,10-tetraoxaspiro[5.5 ]Undecane, bis(1,2,2,6,6-pentamethyl-4-piperidyl)-2-butyl-2-(3,5-di-tert-butyl-4-hydroxybenzyl)malonate, 1-(2- hydroxyethyl)-2,2,6,6-tetramethyl-4-piperidinol/diethyl succinate polycondensate, 1,6-bis(2,2,6,6-tetraethyl-4-piperidylamino)hexane/dibromo Ethane polycondensate, 1,6-bis(2,2,6,6-tetramethyl-4-piperidylamino)hexane/2,4-dichloro-6-morpholino-s-triazine polycondensate, 1,6- Bis(2,2,6,6-tetramethyl-4-piperidylamino)hexane/2,4-dichloro-6-tertiary octylamino-s-triazine polycondensate, 1,5,8,12-tetrakis [ 2,4-bis(N-butyl-N-(2,2,6,6-tetramethyl-4-piperidyl)amino)-s-triazin-6-yl]-1,5,8,12-tetraaza Dodecane, 1,5,8,12-tetrakis[2,4-bis(N-butyl-N-(1,2,2,6,6-pentamethyl-4-piperidyl)amino)-s-triazine-6- yl]-1,5,8,12-tetraazadodecane, 1,6,11-tris[2,4-bis(N-butyl-N-(2,2,6,6-tetramethyl-4-piperidyl) ) amino)-s-triazin-6-ylamino]undecane, and 1,6,11-tris[2,4-bis(N-butyl-N-(1,2,2,6,6-pentamethyl-4- Examples include piperidyl)amino)-s-triazin-6-ylamino]undecane.

Stabilizers include, for example, tin-based stabilizers such as dialkyltin dicarboxylates, dialkyltin maleate esters, and dialkyltin mercaptides, as well as organic acids (octanoic acid, 2-ethylhexanoic acid, capric acid, lauric acid, myristic acid, etc.). acids, palmitic acid, stearic acid, oleic acid, eicosanoic acid, behenic acid, and benzoic acid, etc.) metals (Li, Na, K, Cs, Cu, Be, Mg, Ca, Sr, Ba, Zn, Cd) , Sn, and Pb) salts. These stabilizers are preferably used when vinyl chloride resin is used.

Light stabilizers include benzophenone compounds, benzotriazole compounds, and cyanoacrylate compounds.

Examples of benzophenone compounds include 2,3'-dihydroxy-4,4'-dimethoxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, and 2,2',4,4'-tetrahydroxybenzophenone. Can be mentioned.

Examples of benzotriazole compounds include 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-5'-methylphenyl)-5,6-dichlorobenzotriazole, 2-(2'-hydroxy-5'-t-butylphenyl)benzotriazole, 2-(2'-hydroxy-3'-methyl-5'-t-butylphenyl)benzotriazole, 2-(2'-hydroxy -3',5'-di-t-butylphenyl)-5-chloro-benzotriazole, 2-(2'-hydroxy-5'-phenylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy -3',5'-di-t-butylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3'-t-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3',5'-di-t-amylphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-di-t-butylphenyl)benzotriazole, 2- (2'-hydroxy-5'-t-octylphenyl)benzotriazole, 2-{2'-hydroxy-3'-(3'',4'',5'',6''-tetrahydrophthalimidomethyl)-5'-methyl phenyl}benzotriazole, and 2-{2-hydroxy-3,5-bis(α,α′-dimethylbenzyl)phenyl}-2-hydroxybenzotriazole.

Examples of the anoacrylate compound include ethyl-2-cyano-3,3-diphenylacrylate and 2-ethylhexyl-2-cyano-3,3-diphenylacrylate.

Other stabilizing aids include epoxy compounds such as epoxidized soybean oil, epoxidized linseed oil, bisphenol A diglycidyl ether, and hydrogenated bisphenol A diglycidyl ether, as well as benzoylacetone, dibenzoylmethane, and stearoylbenzoylmethane. β-diketone compounds such as the following may also be used.

[Lubricant]
The resin film according to one embodiment may contain a lubricant. Lubricants are broadly classified into external lubricants and internal lubricants. External lubricants include waxes, fatty acid metal soaps, and fatty acid esters. Examples of waxes include polyethylene wax, amide wax, paraffin wax, etc.; examples of fatty acid metal soaps include zinc stearate, barium stearate, magnesium stearate, calcium stearate, etc.; Examples of the fatty acid ester include monoglycerin fatty acid ester, diglycerin fatty acid ester, polyglycerin fatty acid ester, and sorbitan fatty acid ester. Further, examples of the internal lubricant include fatty acid esters, and examples of the fatty acid esters include butyl stearate, monoglycerin fatty acid ester, diglycerin fatty acid ester, polyglycerin fatty acid ester, and sorbitan fatty acid ester. Other internal lubricants include epoxidized soybean oil.

[Other additives]
The additives contained in the resin film are not limited to the above-mentioned plasticizers, stabilizers, and lubricants, but may also include colorants, antistatic agents, processing aids, and the like.

<Light diffusion film 10>
As shown in FIG. 2, a light diffusing film 10 according to one embodiment of the present invention includes a base layer made of a resin film 1 according to one embodiment of the present invention, and an adhesive layer formed on one surface of the resin film 1. and a coating layer 2. Further, in the light diffusion film 10 according to one embodiment, the adhesive layer 2 may be protected by the release film 4. Note that since the resin film 1 is one embodiment of the resin film according to the present invention, its description will be omitted.

[Adhesive layer 2]
The adhesive layer 2 may be formed of a known adhesive such as an acrylic adhesive, a silicone rubber adhesive, or a synthetic rubber adhesive. The adhesive composition for forming the adhesive layer 2 is more preferably an acrylic adhesive because it has excellent light transmittance, light stability, and thermal stability.

The acrylic copolymer contained in the acrylic adhesive includes an acrylic ester monomer as the main copolymer unit, and other monomers include an acrylic ester monomer having a hydroxyl group, and a carboxyl ester monomer. It is preferable that the monomer contains an acrylic acid ester monomer having a group. The acrylic pressure-sensitive adhesive can be crosslinked with a crosslinking agent by containing an acrylic ester monomer having a hydroxyl group and an acrylic ester monomer having a carboxyl group as monomer units. Examples of such acrylic adhesives include the Nissetsu (registered trademark) series (manufactured by Nippon Carbide Industries Co., Ltd.).

Examples of crosslinking agents include isocyanate crosslinking agents, melamine crosslinking agents, benzoguanamine crosslinking agents, urea crosslinking agents, metal chelate crosslinking agents, organosilane crosslinking agents, epoxy crosslinking agents, and acid anhydride crosslinking agents. It is more preferable that the crosslinking agent is an isocyanate-based crosslinking agent. Examples of isocyanate-based crosslinking agents include CK-117 (manufactured by Nippon Carbide Industries, Ltd.), and examples of melamine-based crosslinking agents include Nikalac (registered trademark) MS-11 and MS-001 (both manufactured by Nippon Carbide Industries, Ltd.). Co., Ltd.) and Mycoat 715 (manufactured by Japan Cytec Industries Co., Ltd.; "Mycoat" is a registered trademark of Allnex Japan Co., Ltd.).

The thickness of the adhesive layer 2 is within the range of 1 μm or more and 200 μm or less, more preferably 5 μm or more and 100 μm or less. When the thickness of the adhesive layer 2 is 1 μm or more, the adhesive layer 5 with suitable adhesiveness can be formed, and when the thickness of the adhesive layer 5 is 200 μm or less, the light diffusion film 10 can be formed. can be attached to suitably follow the curved surface or unevenness of the adherend.

In addition, it is preferable that the adhesive layer 2 included in the light diffusion film 10 according to one embodiment contains inorganic particles and resin particles.

The inorganic particles contained in the adhesive layer 2 are the same as those contained in the resin film described above. In addition, the resin particles include cross-linked benzoguanamine resin beads (refractive index 1.65 to 1.66), cross-linked melamine resin beads (refractive index 1.65 to 1.66), silicone resin beads (refractive index 1.42), and acrylic resin beads. Examples include resin beads (1.50).

In addition, the adhesive layer 2 may contain, for example, antioxidants, stabilizers such as ultraviolet absorbers, leveling agents, antisettling agents, antifoaming agents, wetting and dispersing agents, etc., within the range that does not impair the effects of the present invention. It may also contain additives such as activators, plasticizers, etc. as other components.

(Release film 4)
The release film 4 is a film that can protect the adhesive layer 2 before the light-diffusing film is attached to the adherend, and its type is not limited as long as it has releasability. Examples of such a release film include a polyethylene terephthalate (PET) resin film whose surface is treated with a silicone resin, a fluororesin, or the like.

[Light diffusion film]
Using FIGS. 3 and 4, use of the light diffusion film 11 according to one embodiment of the present invention will be described. FIG. 3 is a diagram schematically illustrating a light diffusion film 11 according to one embodiment of the present invention.

In the light diffusing film 11 according to one embodiment of the present invention shown in FIG. 3, a printed layer 3 is formed on the back side of the surface of the light diffusing film 10 on which the adhesive layer 2 is formed. Description of the light diffusion film 10 will be omitted.

[Printing layer 3]
The printing layer 3 included in the light diffusion film 11 shown in FIG. 3 is a layer formed by applying ink onto the resin film 1. The ink may be any known ink used in inkjet printing or screen printing, and includes, for example, solvent-based ink, water-based emulsion-based ink, photocurable ink, and the like. Furthermore, the printing layer 3 does not need to be a single ink layer; for example, it may include a clear ink layer made of clear ink on a color ink layer, or an overlaminate layer may be provided.

As described above, the light diffusion film 11 includes the resin film 1, and the resin film 1 has a content of inorganic particles of 10 parts by mass or more and 60 parts by mass or less with respect to 100 parts by mass of the first thermoplastic resin. Printability with ink or the like on the surface of the film 1 is excellent.

Note that the release film 4 of the light diffusion film 11 is peeled off before being attached to the light source 5, which is an adherend.

FIG. 4 is a diagram illustrating the outline of use of the light diffusion film 11. As shown in FIG. 4, a light diffusion film 11 according to one embodiment of the present invention is used by being attached to a light-transmitting base material 5b provided in a light source 5. The light diffusion film 11 attached to the light-transmitting base material 5b is irradiated with light L from the light-emitting source 5a through the light-transmitting base material 5b. The light diffusion film 11 has a haze of 70% or more and 98% or less while containing inorganic particles. Therefore, while suitably diffusing the light L, the light L is not excessively blocked. Therefore, it is suitably used as a light diffusion film for internally illuminated display devices such as internally illuminated signs, screens for transmission type projectors, panels for diffusing natural light, windows, lighting boards, arcades, etc.

Examples of the light emitting source 5a include, but are not limited to, light emitting diodes (LEDs), fluorescent lights, and the like.

The light-transmitting base material 5b may be a base material molded from glass or transparent resin. Examples of the glass used for the light-transmitting base material 5b include various glasses represented by soda-lime glass, borosilicate glass, lead glass, aluminosilicate glass, borate glass, and phosphate glass.

Further, examples of the transparent resin used for the light-transmitting base material 5b include acrylic resin, halogen-containing resin represented by vinyl chloride, polystyrene, polyester, polycarbonate, and polyolefin.

<Manufacture of resin film>
A method for manufacturing a resin film according to one embodiment of the present invention includes a step of kneading inorganic particles and a thermoplastic resin to obtain a kneaded product, and a step of molding a resin film from the kneaded product.

The process of manufacturing a resin film includes a step of pre-kneading a second thermoplastic resin and inorganic particles to obtain a pre-kneaded product, and a step of kneading the obtained pre-kneaded product with the first thermoplastic resin. It is more preferable that it contains.

At the stage of obtaining a pre-kneaded product, the second thermoplastic resin and inorganic particles are pre-kneaded to eliminate agglomerates of inorganic particles that cause dot dropouts, and the inorganic particles are dispersed as a uniform dispersed phase in the resin film. can be distributed. Preliminary kneading of the second thermoplastic resin and inorganic particles may be performed using, for example, a stirring device such as a Henschel mixer. Further, the temperature at which the second thermoplastic resin and the inorganic particles are pre-kneaded may be determined depending on the type of the second thermoplastic resin. good.

In the step of kneading the preliminary kneaded material and the first thermoplastic resin, a kneading device such as a roll mixer, a Banbury mixer, a pressure kneader, and a twin-screw extruder may be used. Here, the kneading temperature may be determined depending on the type of the first thermoplastic resin, and may be, for example, 150 to 200°C.

In the step of forming a resin film from the kneaded material, various film forming methods such as extrusion method, calendar method, sol cast method, melt cast method, etc. can be used depending on the type of the first thermoplastic resin.

<Manufacture of light diffusion film>
A method for manufacturing a light diffusing film according to one embodiment of the present invention includes a step of manufacturing a resin film according to one embodiment of the present invention, and a step of forming an adhesive layer on one side of the manufactured resin film. ing. The step of forming the adhesive layer may include the steps of applying an adhesive composition and drying the applied adhesive composition.

The step of applying the adhesive composition may be a step of applying the adhesive composition on a resin film or a release film, and methods for applying the adhesive composition include known coating methods. . Examples of such coating methods include screen printing, gravure printing, bar coating, knife coating, roll coating, comma coating, blade coating, die coating, spray coating, electrostatic coating and dip coating. included. Note that, from the viewpoint of coating workability, the adhesive composition preferably contains a known diluting solvent such as ethyl acetate.

The step of drying the applied adhesive composition may be, for example, a step of drying the coating liquid composition or ink by heating with a known heating device, and the known heating device includes, for example, an infrared heater, a hot air heater, etc. Examples include a heater or a heating device such as an oven or a hot plate. In the step of forming the adhesive layer, the evaporation of the diluent contained in the adhesive composition and the crosslinking reaction of the resin contained in the adhesive composition are promoted, and the adhesive layer can be formed.

In the step of forming the adhesive layer, when the adhesive layer is formed on the resin film, a release film may be attached to the adhesive layer to protect the adhesive layer. Furthermore, when an adhesive layer is formed on a release film, it is preferable to attach a resin film to the adhesive layer.

Thereafter, a printed layer may be formed on the surface of the resin film by inkjet printing or screen printing.

〔summary〕
The resin film according to one aspect of the present invention contains a first thermoplastic resin, a second thermoplastic resin, and inorganic particles, and the second thermoplastic resin is added to 100 parts by mass of the first thermoplastic resin. The content of the inorganic particles is 5 parts by mass or more, and the content of the inorganic particles is 10 parts by mass or more and 60 parts by mass or less relative to 100 parts by mass of the first thermoplastic resin. This greatly increases the dispersibility of the inorganic particles in the first and second thermoplastic resins. Therefore, aggregates of inorganic particles that cause missing dots can be eliminated, and the inorganic particles can be dispersed as a uniform dispersed phase in the resin film. Therefore, the resin film has high light diffusivity and low brittleness while containing inorganic particles. Moreover, the resin film has high printability on the surface of the resin film by containing inorganic particles.

Further, in the resin film according to one aspect of the present invention, the storage elastic modulus of the second thermoplastic resin at 23°C is 10 to 1200 MPa, which is higher than the storage elastic modulus of the first thermoplastic resin at 23°C. It is also preferable that the temperature is also low. Thereby, the dispersibility of the inorganic particles in the resin film is sufficiently increased, and embrittlement of the resin film is sufficiently suppressed.

Further, the resin film according to one embodiment of the present invention preferably has a haze of 70% or more and 98% or less. Thereby, the resin film can be suitably used for, for example, an internally illuminated display device.

Further, in the resin film according to one aspect of the present invention, it is preferable that the inorganic particles are one or both of calcium carbonate and silica. Thereby, high printability can be imparted to the surface of the resin film while providing high light diffusivity.

Further, the second thermoplastic resin contained in the resin film according to one embodiment of the present invention is at least one thermoplastic resin selected from the group consisting of polyurethane resin, (meth)acrylic resin, and polyester resin. . The second thermoplastic resin selected from these thermoplastic resins can further improve the dispersibility of the inorganic particles.

The resin film according to one embodiment of the present invention more preferably contains a polyurethane resin as the second thermoplastic resin. From the viewpoint of weather resistance and compatibility with the first thermoplastic resin, it is preferable to use a polyurethane resin as the second thermoplastic resin.

In the resin film according to one aspect of the present invention, the content of the second thermoplastic resin relative to 100 parts by mass of the first thermoplastic resin is more preferably 15 parts by mass or less. Thereby, the brittleness of the resin film is suppressed, and a resin film having sufficient strength as a display film can be obtained.

Moreover, in the resin film according to one aspect of the present invention, it is preferable that the thermoplastic resin contains a vinyl chloride resin. As a result, a resin film with good outdoor weather resistance can be obtained.

In the light-diffusing film according to one aspect of the present invention, an adhesive layer may be formed on one surface of a resin film, and the adhesive layer may include light-diffusing particles.

Thereby, the light diffusion film is provided with high light diffusion by both the resin film layer and the adhesive layer.

Further, in the light diffusion film according to one aspect of the present invention, a printed layer is formed on the back side of the surface of the resin film layer on which the adhesive layer is formed. The light diffusion film can provide high printability to the surface of the resin film.

The present invention is not limited to the embodiments described above, and various modifications can be made within the scope of the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. are also included within the technical scope of the present invention.

Examples of the present invention will be described below.
Films according to Examples 1 to 9 and Comparative Examples 1 to 5 were produced and evaluated for haze, tensile elongation, and dot dropout.

<Preparation of resin film>
Resin films of Examples 1 to 9 and Comparative Examples 1 to 5 were produced using the materials shown below.
[First thermoplastic resin]
Vinyl chloride resin-1:
Kanevinyl (registered trademark) S1008, manufactured by Kaneka Co., Ltd. Average degree of polymerization: 800, storage modulus 1709MPa (23°C)
[Second thermoplastic resin]
Polyurethane resin-1:
Pandex (registered trademark) T-R3080
Manufactured by DIC Covestro Polymer Co., Ltd., storage modulus 37 MPa (23°C)
(Meth)acrylic resin-1:
Parapet (registered trademark) SA-1000-FP
Manufactured by Kuraray Co., Ltd., storage modulus 54 MPa (23°C)
(Meth)acrylic resin-2:
Parapet (registered trademark) GR-F
Manufactured by Kuraray Co., Ltd., storage modulus 1024 MPa (23°C)
Polyester resin-1:
Byron (registered trademark) 600
Manufactured by Toyobo Co., Ltd. [Inorganic particles]
Inorganic particles-1: SL-1500 (calcium carbonate, manufactured by Takehara Chemical Industry Co., Ltd.)
Volume median diameter 2.0 μm, refractive index 1.65
Inorganic particles-2: Silicia 445 (Silica, Fuji Silicia Co., Ltd.)
Volume median diameter 3.5μm, refractive index 1.45
[Other additives]
Plasticizer-1: ADEKASIZER (registered trademark) PN-446 (manufactured by ADEKA Co., Ltd.)
Adipic acid polyester, number average molecular weight 2000, solid content 100% by mass
Stabilizer-1: ADEKA STAB (registered trademark) AC-258 (manufactured by ADEKA Co., Ltd.)
Barium/zinc type (Ba/Zn type) stabilizer, solid content 100% by mass
Stabilizer-2: ADEKA STAB (registered trademark) CPL-1563 (manufactured by ADEKA Co., Ltd.)
Solid content: 100% by mass
External lubricant-1: AC-6A (Honeywell)
Polyethylene wax internal lubricant-1: Butyl stearate (Kawaken Fine Chemical Co., Ltd.)

[Example 1]
Polyurethane resin-1 and inorganic particles-1 were kneaded with the contents shown below using a twin-screw extruder in opposite directions, and pelletized to obtain pellets of pre-kneaded product I.
Polyurethane resin - 1: 8 parts by mass Inorganic particles - 1: 15 parts by mass

Next, using a Henschel mixer, vinyl chloride resin-1, plasticizer-1, stabilizer-1, stabilizer-2, external lubricant-1 and internal lubricant-1 were heated to 90°C with the following contents: The mixture was stirred until the temperature reached 100 degrees, and then cooled to room temperature to obtain a pre-kneaded product II.
Vinyl chloride resin-1: 100 parts by mass Plasticizer-1: 30 parts by mass Stabilizer-1: 2.7 parts by mass Stabilizer-2: 1.2 parts by mass External lubricant-1: 0.2 parts by mass Internal lubricant -1: 2.0 parts by mass

After that, the pre-kneaded material II obtained was re-stirred in the Henschel mixer, and the entire amount of pellets of the pre-kneaded material I was added, and then using a two-roll roll mixer, the roll temperature was 160 ° C. for 10 minutes. A compound was obtained by melt-kneading. After melt-kneading, the compound was rolled using four calendar rolls arranged in an inverted L shape at a roll temperature of 175°C to 185°C to form a film with a thickness of 50 μm.

[Examples 2 to 10, Comparative Examples 1 to 4]
The resin films of Examples 2 to 10 and the resin films of Comparative Examples 1 to 4 were produced under the same conditions as in Example 1, except that Prekneaded Materials I were produced with the compositions shown in Table 1.

<Haze measurement>
Haze was measured using a haze meter (manufactured by Nippon Denshoku Kogyo Co., Ltd., NDH-2000). Table 1 shows the haze evaluation results.

<Tensile test (breaking elongation)>
The resin films of Examples 1 to 10 and the resin films of Comparative Examples 1 to 4 were each cut to a width of 150 mm x 10 mm to obtain test pieces. The elongation at break was evaluated by pulling the test piece using a tensile tester at a tensile speed of 200 mm/min, a distance between chucks of 100 mm, and a measurement temperature of 10° C., and measuring the elongation at break. The evaluation criteria for elongation at break are as shown below, and Table 1 shows the evaluation results for elongation at break.
〔Evaluation criteria〕
Excellent: Elongation at break was 100% or more.
Good: The elongation at break was 50% or more and less than 100%.
Fair: The elongation at break was 20% or more and less than 50%.
Not acceptable: The elongation at break was less than 20%.

<Evaluation of missing dots>
The resin films of Examples 1 to 10 and the resin films of Comparative Examples 1 to 4 were each cut into 200 mm square pieces to obtain test pieces. For evaluation of missing dots, an LED light source was placed to illuminate the back side of the test piece from a position 100 mm away, and the number of missing dots confirmed as black spots was counted when the film was viewed from the front. The evaluation criteria for missing dots are as shown below, and Table 1 shows the evaluation results for missing dots.
〔Evaluation criteria〕
Good: There were no missing dots.
Fair: There were 1 to 3 missing dots.
Not acceptable: There were 4 or more missing dots.

As shown in Table 1, the resin films of Examples 1 to 9 had a haze of between 70 and 98% and a high elongation at break of 20% or more. In the resin film of Example 10, it was confirmed that the haze increases when the second thermoplastic resin is large. The resin film of Comparative Example 1 had a low content of inorganic particles-1 and a low haze. In addition, from the results of Comparative Example 2 and Comparative Example 3 resin films, it was confirmed that when the amount of inorganic particles-1 is large or the amount of the second thermoplastic resin is small, the haze is as high as 99% and the elongation at break becomes low. did. Moreover, since the resin film of Comparative Example 4 did not contain the second thermoplastic resin, the elongation at break was low.

The present invention is used for an internally illuminated display device (also referred to as an internally illuminated display device) that displays information using light from inside, and a light diffusion sheet that diffuses natural light. Specifically, lighting equipment using lighting covers, illuminated signboards such as light pillars and light walls, internally illuminated display devices such as illuminated signboards and internally illuminated signs, internally illuminated displays used in gaming machines, vending machines, etc. It is possible to provide light diffusion sheets used for devices, screens of transmission type projectors, panels for diffusing natural light, windows, daylighting boards, arcades, etc.

1 Resin film 2 Adhesive layer 3 Print layer 4 Release film 5 Light source 5a Light source (light source)
5b Light-transparent base material (light source)
10 Light Diffusion Film 11 Light Diffusion Film

Claims (6)

Containing a first thermoplastic resin, a second thermoplastic resin and inorganic particles,
The content of the second thermoplastic resin relative to 100 parts by mass of the first thermoplastic resin is 5 parts by mass or more,
The content of the inorganic particles relative to 100 parts by mass of the first thermoplastic resin is 10 parts by mass or more and 60 parts by mass or less,
the first thermoplastic resin includes a vinyl chloride resin,
the second thermoplastic resin includes a polyurethane resin,
The inorganic particles have a refractive index of 1.40 to 2.80, and the volume median diameter of the inorganic particles is 1 μm to 10 μm ,
The storage modulus of the second thermoplastic resin at 23° C. is 10 MPa or more and 1200 MPa or less, and is lower than the storage modulus of the first thermoplastic resin at 23° C.
resin film. The resin film according to claim 1, having a haze of 70% or more and 98% or less. The resin film according to claim 1 or 2, wherein the content of the second thermoplastic resin with respect to 100 parts by mass of the first thermoplastic resin is 15 parts by mass or less. The resin film according to any one of claims 1 to 3, wherein the inorganic particles are one or both of calcium carbonate and silica . An adhesive layer is formed on one side of the resin film according to any one of claims 1 to 4,
A light-diffusing film in which the adhesive layer includes light-diffusing particles. The light diffusing film according to claim 5, wherein a printing layer is formed on the back side of the surface of the resin film layer on which the adhesive layer is formed.

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