TW201902946A - Photocurable resin composition for light guide, cured product for light guide, light guide, and optical integrator - Google Patents

Abstract

Provided are: a light guide body having superior light resistance; a photocurable resin composition for light guide bodies, which is used to obtain such a light guide body; a cured product for light guide bodies, which is obtained by curing the photocurable resin composition; and a light integrator. Specifically, the photocurable resin composition for light guide bodies contains: (A) a bifunctional (meth)acrylate; and (B) a hexafunctional (meth)acrylate including (b1) an aliphatic hydrocarbon group which contains or does not contain an oxygen atom, and (b2) a (meth)acryloyl group.

Description

Photocurable resin composition for light guide, hardened material for light guide, light guide, and optical integrator

The present invention relates to a photocurable resin composition for a light guide, a cured product for a light guide, a light guide, and an optical integrator.

Color liquid crystal display devices have been widely used in various fields for the following applications: mobile phones, digital cameras, digital video cameras, portable game consoles, notebook computers, and LCD televisions. This liquid crystal display device basically includes a surface light source device. As the surface light source device, there are an edge lighting method and a direct type, and generally, an edge lighting method is often used. The edge illumination method is a method in which a light-transmitting flat-shaped light guide (light guide plate) is used, and a light source is disposed on a side surface (incident surface) of the light guide, so that light is emitted from the entire surface of the light guide. (Refer to Patent Documents 1 and 2) In general, screens of notebook computers, desktop computers, and smartphones have adopted this edge lighting method.

In the currently popular surface light source devices, the light emitted from the light source is incident from the incident surface of the side surface of the light guide and is introduced into the light guide. The light introduced into the light guide body is deflected and reflected in a reflection groove provided on the reflection surface (back surface) of the light guide body, and then is emitted from the exit surface (surface) of the light guide body. Although a part of the light is emitted from the reflecting surface side, it is reflected by a reflector disposed opposite to the reflecting surface, and then enters the light guide again. The light emitted from the exit surface (surface) of the light guide is diffused and deflected by the optical film, and is emitted toward the normal direction of the optical film (see Patent Document 3).

However, in recent years, mounting-type component devices, so-called wearable terminals, have been attracting attention. They are different from smart phones and notebook computers and can be used while being worn on the body. Examples of the form of the wearable terminal include glasses and watches, and any form is desperately desired to be miniaturized and lightened.回应 In response to such a request, a miniaturization and weight reduction of a light source device used in a wearable terminal or the like is being sought, and the light source device is used to project an image. However, when trying to miniaturize and lighten the light source device, the distance between the light source and the light guide body will be closer. Therefore, the light resistance required for the light guide body is higher than before, and the light guide body is required. The materials are further studied. As a material of the light guide, for example, Patent Document 4 has listed an acrylic resin, which is typified by polymethyl methacrylate resin (PMMA). [Prior Art Literature] (Patent Literature)

Patent Literature 1: Japanese Patent Laid-Open No. 2005-142078 Patent Literature 2: Japanese Patent Laid-Open No. 2008-218418 418 Patent Literature 3: Japanese Patent Laid-Open No. 2015-055772 Patent Literature 4: Japanese Patent Laid-Open No. 2015-194628

[Problems to be Solved by the Invention] However, after conducting research, the present inventors found the following facts: Although the type of acrylic resin varies, the color may change due to the light from the light source, which may cause the brightness to decrease. It may not be able to satisfy the severe light resistance sought for, for example, a light guide for a wearable terminal, and there is still room for further improvement. Therefore, the problem to be solved by the present invention is to provide: a light guide having excellent light resistance; a photocurable resin composition for a light guide used to obtain such a light guide; and a light guide to be hardened An object, which is obtained by curing the light-curable resin composition for a light guide; and an optical integrator. [Technical means to solve the problem]

The present inventors have made intensive research in order to solve the above-mentioned problems to be solved. As a result, they found that if it is a photocurable resin composition, they can solve the above-mentioned problems and are suitable for use as light guides. The photocurable resin composition contains: (A) a 2-functional (meth) acrylate; and (B) a 6-functional (meth) acrylate, which is an aliphatic group containing or not containing an oxygen atom. A hydrocarbon group (b1) and a (meth) acrylfluorenyl group (b2). The present invention has been completed based on such a technical idea.

The present invention relates to the following techniques [1] to [20]. [1] A light-curable resin composition for a light guide, comprising: (A) a bifunctional (meth) acrylate; and (B) a 6-functional (meth) acrylate, which contains or does not contain An oxygen atom-containing aliphatic hydrocarbon group (b1) and a (meth) acrylfluorenyl group (b2). [2] The photocurable resin composition for a light guide according to the above [1], in a content ratio of the component (A) and the component (B), a total number of functional groups of the component (A) (A) / (B) with respect to the total number of functional groups of the said (B) component is 1.1-8. [3] The photocurable resin composition for a light guide according to the above [1] or [2], in the content ratio of the component (A) and the component (B), the component (A) The total number of functional groups is 1.3 to 5 with respect to the total number of functional groups of the component (B), that is, (A) / (B). [4] The photocurable resin composition for a light guide according to any one of the above [1] to [3], wherein in the content ratio of the component (A) and the component (B), the component The total functional group number of the component (A) is 1.3 to 3.60, that is, the total functional group number of the component (B), that is, (A) / (B). [5] The photocurable resin composition for a light guide according to any one of the above [1] to [4], further containing a total amount of the component (A) and the component (B) It is 5 mol (mol)% or less of a 6-functional (meth) acrylate containing an urethane bond or a 6-functional (meth) acrylate containing an urethane bond. [6] The photocurable resin composition for a light guide according to any one of the above [1] to [5], which does not contain a 6-functional (meth) acrylate containing an amine ester bond. [7] The photocurable resin composition for a light guide according to any one of the above [1] to [6], wherein the component (A) contains a component containing a structure represented by the following formula (A1) 2-functional (meth) acrylate: In the formula (A1), m ¹ is an integer of 1 to 10, and * represents a site bonded to another group. [8] The photocurable resin composition for a light guide according to any one of the above [1] to [7], wherein the component (A) contains a component containing a structure represented by the following formula (A2) 2-functional (meth) acrylate: In formula (A2), n ¹ and n ² are each independently an integer of 1 to 5, and satisfy 2 ≦ n ¹ + n ² ≦ 10, X is a linking group containing an aromatic hydrocarbon group, and * represents a bond with another group The location. [9] The photocurable resin composition for a light guide according to any one of the above [1] to [8], wherein the molecular weight of the component (A) is 150 to 700. [10] The photocurable resin composition for a light guide according to any one of the above [1] to [9], wherein the component (A) contains a compound comprising a polyethylene glycol diacrylate and an epoxy resin. At least one selected from the group consisting of ethane-modified bisphenol A diacrylate. [11] The photocurable resin composition for a light guide according to any one of the above [1] to [10], wherein the component (A) contains polyethylene glycol diacrylate and ethylene oxide Modified bisphenol A diacrylate. [12] The photocurable resin composition for a light guide according to the above [11], wherein the content ratio of the ethylene oxide modified bisphenol A diacrylate to the polyethylene glycol diacrylate is That is, the ethylene oxide modified bisphenol A diacrylate / polyethylene glycol diacrylate has a molar ratio of 0.40 or less. [13] The photocurable resin composition for a light guide according to any one of the above [1] to [12], wherein the component (B) includes a structure represented by the following formula (B1): In the formula (B1), * represents a site bonded to another group. [14] The photocurable resin composition for a light guide according to any one of the above [1] to [13], wherein the molecular weight of the component (B) is 350 to 3,000. [15] The photocurable resin composition for a light guide according to any one of the above [1] to [14], wherein the component (B) is selected from the following compounds (B1-1) to ( B1-3) At least one selected from the group consisting of: In the above formulae (B1-1) to (B1-3), * ¹ represents a bond with any one of the *, and R ² is a hydrogen atom or a methyl group; in a compound, a plurality of R ² may be the same or different. . [16] A cured product for a light guide, which is obtained by curing the photocurable resin composition for a light guide according to any one of [1] to [15]. [17] The cured product for a light guide according to the above [16], wherein the elastic modulus is 400 to 1,000 MPa. [18] A light guide having: an incident surface on which incident light from a light source is incident; and an exit surface, which is incident light incident from the aforementioned incident surface, propagates through a medium provided therein as an exit surface. The emitted light is emitted from the emitting surface; and the medium is a hardened material for a light guide according to [16] or [17]. [19] The light guide according to the above [18], wherein the exit light emitted from the exit surface is more uniform than the incident light incident from the entrance surface. [20] An optical integrator composed of the light guide body described in [18] or [19] above. [efficacy]

According to the present invention, it is possible to provide: a light guide having excellent light resistance; a light-curable resin composition for a light guide for obtaining such a light guide; and a hardened material for a light guide which uses The light guide is hardened with a photocurable resin composition; and an optical integrator. The light guide of the present invention can reduce the size and weight of the light source device.

Hereinafter, the present invention will be described in detail. In the numerical range described in the present invention, the upper limit value or lower limit value of the numerical range may be replaced with the value disclosed in the embodiment. In addition, the lower limit value and the upper limit value of the numerical range can be arbitrarily combined with the lower limit value and the upper limit value of other numerical ranges, respectively.态 Any combination of the matters described in this specification is also included in the present invention.

[Photocurable resin composition for light guide] 光 The photocurable resin composition for light guide of the present invention contains (A) a bifunctional (meth) acrylate [sometimes referred to as (A) component] ; And, (B) a 6-functional (meth) acrylate composed of an aliphatic hydrocarbon group (b1) with or without an oxygen atom and a (meth) acrylfluorenyl group (b2) [sometimes called ( B) Ingredients]. In addition, in the present invention, "bifunctional" and "6-functional" mean that they have two (meth) acrylfluorene groups and six (meth) acrylfluorene groups, even if they have (meth) acrylfluorene The functional group other than the functional group and the functional group other than the (meth) acrylfluorene group are not included in the number of the functional groups referred to herein. The number of functional groups when referred to as "the number of functional groups" or "the total number of functional groups" also refers to the number of (meth) acrylfluorenyl groups, and does not include functional groups other than (meth) acrylfluorene. For example, a compound having two (meth) acrylfluorenyl groups and having a functional group (for example, a hydroxyl group) other than one (meth) acrylfluorene group is a "bifunctional (meth) acrylate". Hereinafter, the components contained in the photocurable resin composition for a light guide of the present invention will be described in order.

((A) Bifunctional (meth) acrylate) The (A) component is used to impart flexibility to a cured product of the photocurable resin composition for a light guide of the present invention, and has a function of adjusting the refractive index. The bifunctional (meth) acrylate used as the (A) component may be any of a bifunctional acrylate and a bifunctional methacrylate. Among these, a bifunctional acrylate is preferable from the viewpoint that the reaction proceeds rapidly. From the viewpoint of light resistance, it is preferred that the component (A) does not contain an amine ester bond. The component (A) preferably has one (meth) acrylfluorenyl group at each end of the molecule. The molecular structure other than the (meth) acrylfluorenyl group is not particularly limited, and from the viewpoint of imparting flexibility to the cured product, the component (A) preferably contains 2 containing a structure represented by the following formula (A1) Functional (meth) acrylate. In the formula (A1), m ¹ is an integer of 1 to 10, and * represents a site bonded to another group.

M ¹ in the aforementioned formula (A1) is preferably an integer of 2 to 8, more preferably an integer of 2 to 6, more preferably an integer of 3 to 5, and particularly preferably 4. ＊ indicates a bonding site with other groups. The ＊ may be directly bonded to a (meth) acrylfluorenyl group, and may also be connected via any linking group (where the linking group does not contain an aromatic hydrocarbon group, the linking group For example, an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, and a combination of these) are bonded to a (meth) acrylfluorenyl group. The number of carbon atoms in the linking group is not particularly limited. For example, 1 to 20 is preferable, 1 to 10 is preferable, and 1 to 5 is more preferable.

From the viewpoint of improving the affinity with other components and imparting flexibility to the cured product, the bifunctional (meth) acrylate containing the structure represented by the formula (A1) is preferably the following A bifunctional (meth) acrylate represented by the formula (A1-1). In formula (A1-1), m ¹ is in the formula (A1) m the same ^1, R ¹ are each independently a hydrogen atom or a methyl group. As R ¹ in formula (A1-1), a hydrogen atom is preferred from the viewpoint that the reaction proceeds rapidly.

Moreover, (A) component may contain the bifunctional (meth) acrylate containing the structure represented by following formula (A2). Containing a bifunctional (meth) acrylate containing a structure represented by the following formula (A2), it tends to increase the refractive index and heat resistance. In formula (A2), n ¹ and n ² are each independently an integer of 1 to 5 and satisfy 2 ≦ n ¹ + n ² ≦ 10, X is a linking group containing an aromatic hydrocarbon group, and * represents a bond with another group The location.

N ¹ and n ² in the formula (A2) are each preferably an integer of 1 to 3 independently. n ¹ and n ² preferably satisfy 2 ≦ n ¹ + n ² ≦ 6, and more preferably satisfy 3 ≦ n ¹ + n ² ≦ 6. ＊ indicates a bonding site with other groups, and the ＊ may be directly bonded to a (meth) acrylfluorenyl group, and may also be connected via any linking group (where the linking group does not contain an aromatic hydrocarbon group, the linking group For example, an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, and a group composed of these) are bonded to a (meth) acrylfluorenyl group. The number of carbon atoms in the linking group is not particularly limited. For example, 1 to 20 is preferable, 1 to 10 is preferable, and 1 to 5 is more preferable.

X is a linking group containing an aromatic hydrocarbon group. The aromatic hydrocarbon group is preferably an aromatic hydrocarbon group having a total carbon number of 6 to 20 of the aromatic ring, and more preferably an aromatic hydrocarbon group having a total number of carbons of the aromatic ring. Still more preferred are aromatic hydrocarbon groups having a total of 6 to 12 carbon atoms in the aromatic ring. The aromatic hydrocarbon group may be composed only of an aromatic hydrocarbon group, and a part of the aromatic hydrocarbon group may include at least one selected from the group consisting of an aliphatic hydrocarbon group and an alicyclic hydrocarbon group. Specific examples of the aromatic hydrocarbon group include a group formed by benzene, a group formed by naphthalene, a group formed by biphenyl, a group formed by anthracene, and a group formed by fluorene. Groups formed, groups formed from diphenylmethane, groups formed from diphenylpropane, groups formed from 9,9-diphenylfluorene, and the like. Among these, the aromatic hydrocarbon group is preferably a group formed from benzene, a group formed from diphenylpropane, and more preferably a group formed from diphenylpropane.

Examples of the linking group containing an aromatic hydrocarbon group represented by X include linking groups selected from the following groups. Among them, it is not particularly limited to such a linking group, and it may have a substituent, and a bond for connecting a plurality of aromatic hydrocarbon groups may be long, and may include other various similar structures. The above ** indicates a site bonded to an oxygen atom.

As the linking group containing an aromatic hydrocarbon group represented by X, the following linking group is preferred. The above ** indicates a site bonded to an oxygen atom.

(A) A component may be used individually by 1 type, and may use 2 or more types together. The component (A) may contain both a bifunctional (meth) acrylate containing a structure represented by the formula (A1) and a bifunctional (meth) acrylate containing a structure represented by the formula (A2). , And may contain any of them. When the component (A) contains both a bifunctional (meth) acrylate containing a structure represented by the aforementioned formula (A1) and a bifunctional (meth) acrylate containing a structure represented by the aforementioned formula (A2), The content of the bifunctional (meth) acrylate having the structure represented by the formula (A2) with respect to the content of the bifunctional (meth) acrylate containing the structure represented by the formula (A1), that is, (A2) / (A1) is preferably in a molar ratio of 0.40 or less. If the ratio (A2) / (A1) (molar ratio) is 0.40 or less, it is possible to reduce absorption of light at a short wavelength (450 nm or less), particularly light-emitting diode (LED) light, and further improve light resistance. Propensity. From the same point of view, the ratio (A2) / (A1) (molar ratio) is preferably 0.35 or less, more preferably 0.30 or less, and particularly preferably 0.25 or less. The lower limit value is not particularly limited and may be 0.01 Above, and also 0.05 or more.

From the viewpoint of fluidity during molding, and tensile strength, impact resistance, and chemical resistance of the hardened material, the molecular weight of the component (A) is preferably 150 to 700, more preferably 200 to 650, and 250 to 600 is better. In particular, the molecular weight of the bifunctional (meth) acrylate containing the structure represented by the aforementioned formula (A1) is preferably 150 to 500, more preferably 200 to 400, and includes the structure represented by the aforementioned formula (A2). The molecular weight of the bifunctional (meth) acrylate is preferably 350 to 700, more preferably 400 to 650, and even more preferably 400 to 600.

More specifically, the component (A) preferably contains at least one selected from the group consisting of polyethylene glycol diacrylate and ethylene oxide modified bisphenol A diacrylate, and more Preferably, it contains at least polyethylene glycol diacrylate, and also contains polyethylene glycol diacrylate and ethylene oxide modified bisphenol A diacrylate. The ratio of the content of the ethylene oxide modified bisphenol A diacrylate to the content of the polyethylene glycol diacrylate, that is, the content of the ethylene oxide modified bisphenol A diacrylate / polyethylene glycol diacrylate The ester, in terms of mole ratio, is preferably 0.40 or less, more preferably 0.35 or less, even more preferably 0.30 or less, particularly preferably 0.25 or less. The lower limit value is not particularly limited, and may be 0.01 or more, and may also be Above 0.05.

((B) 6-functional (meth) acrylate, which is composed of an aliphatic hydrocarbon group (b1) with or without an oxygen atom and a (meth) acrylfluorenyl group (b2))) Such a function is described to improve the rigidity of the cured product of the photocurable resin composition for a light guide of the present invention, to improve heat resistance, to improve latent resistance, and to adjust the refractive index. (6) The 6-functional (meth) acrylate used as the (B) component may be any of a 6-functional acrylate and a 6-functional methacrylate. Among these, a 6-functional acrylate is preferable from the viewpoint that the reaction proceeds rapidly. The component (B) is composed of an aliphatic hydrocarbon group (b1) with or without an oxygen atom and a (meth) acrylfluorenyl group (b2) and does not contain an amine ester bond. The aliphatic hydrocarbon group (b1) is preferably a saturated aliphatic hydrocarbon group (b1 '). The component (B) is made of an aliphatic hydrocarbon group (b1) with or without an oxygen atom, and a (meth) acrylfluorenyl group (b2), and does not contain an amine ester bond, so that the light resistance can be extremely excellent.

The component (B) preferably contains a structure represented by the following formula (B1). In the formula (B1), * represents a site bonded to another group.

The structure represented by the aforementioned formula (B1) is a structure remaining after removing 6 hydrogen atoms from dipentaerythritol, and * indicates a site bonded to another group, and the * may be bonded to (meth) acrylfluorenyl (b2) They are directly bonded together, and may also be bonded to (meth) acrylfluorenyl (b2) via any linking group. In the formula (B1), each * is preferably directly or indirectly bonded to one (meth) acrylfluorenyl group (b2). Examples of the linking group include the following linking groups. In the formula, p is an integer of 1 to 8, q is an integer of 1 to 3, * ¹ represents a site bonded to an oxygen atom in formula (B1), and * ² represents a (meth) acrylfluorenyl group (b2). Bonding site. p is the number of repeating units of a methylene group, and an integer of 3 to 7 is preferable, an integer of 4 to 6 is preferable, and 5 is more preferable. q is the number of repeating units of the group surrounded by [] in the above formula, and is preferably 1 or 2, and may be 1 or 2. The aforementioned linking group is preferably the following linking group. In the formula, * ¹ represents a site bonded to an oxygen atom in formula (B1), and * ² represents a site bonded to (meth) acrylfluorenyl (b2).

The component (B) is more preferably at least one selected from the group consisting of the following compounds (B1-1) to (B1-3), and even more preferably is selected from the following compound (B1-1) ) ～ (B1-3) One selected from the group consisting of: In the above formulae (B1-1) to (B1-3), * ¹ represents a bond with any one of the *, and R ² is a hydrogen atom or a methyl group; in a compound, a plurality of R ² may be the same or different. . In the above formulae (B1-1) to (B1-3), from the viewpoint that the reaction proceeds rapidly, R ² is preferably a hydrogen atom. In one compound, a plurality of R ^{2 are} preferably the same, and more preferably all of them are hydrogen atoms.

(B) A component may be used individually by 1 type, and may use 2 or more types together. From the viewpoint of fluidity during molding and tensile strength, impact resistance, and chemical resistance of the hardened material, the molecular weight of the component (B) is preferably 350 to 3,000, more preferably 350 to 2,000, and 450 to 2,000. More preferably, it is particularly preferably 550 to 1,800. For example, the molecular weight of (B) component may be 350-1,000, and may be 550-1,000, and may be 550-650. In addition, it may be 700 to 900, and may be 1,200 to 2,000, and may be 1,500 to 2,000, and may be 1,500 to 1,800.

(Content ratio of (A) component and (B) component) In the photocurable resin composition for a light guide of the present invention, the content ratio of the (A) component and the (B) component is not particularly limited. From the viewpoint, the total number of functional groups of the component (A) is preferably 1.1 to 8 with respect to the total number of functional groups of the component (B), that is, (A) / (B). In addition to the light resistance, from the viewpoint that the photocurable resin composition for a light guide of the present invention has a moderate modulus of elasticity and excellent cuttability of the cured product, it is more preferable that The total number of functional groups is 1.3 to 5, that is, the total number of functional groups of the (B) component, that is, (A) / (B), and more preferably the total number of functional groups of the (A) component relative to the total of the (B) component. The number of functional groups, that is, (A) / (B) is 1.3 to 3.60. When the photocurable resin composition for a light guide of the present invention contains a 6-functional (meth) acrylate not corresponding to the component (B), the denominator of the above ratio can be replaced with the component (B). The total number of functional groups and the number of functional groups of the 6-functional (meth) acrylate not corresponding to the (B) component, and in this case, the preferred numerical range is also the same as described above. Here, the term “excellent dicing property” means that the cured product of the photocurable resin composition for a light guide of the present invention can be cut smoothly and no chips are generated during cutting. When fragments are generated when a cured product is cut to form a light guide, the reflection performance is lowered, and therefore, excellent cutting properties tend to be sought.

Furthermore, if the elastic modulus of the hardened | cured material of the photocurable resin composition for light guides of this invention is too low, that is, a hardened | cured material is too soft, it will load a cutting blade when cutting, and it is unpreferable. On the other hand, if the elastic modulus of the cured product of the photocurable resin composition for a light guide of the present invention is too high, that is, the cured product is too hard, fragments are likely to be generated during cutting, and the reflection performance tends to decrease. Not good. Therefore, from the viewpoint of obtaining excellent cutting properties, the elastic modulus of the cured product of the photocurable resin composition for a light guide of the present invention is preferably 400 to 1,000 MPa, more preferably 450 to 1,000 MPa, and 500 ~ 1,000 MPa is better.

(Other components) 光 The photocurable resin composition for a light guide of the present invention may contain other components than the aforementioned (A) component and the aforementioned (B) component as long as the effects of the invention are not impaired. As the other component, a conventional component that can be used as a material of a light guide can be used. Examples include (meth) acrylate compounds, photopolymerization initiators, scattering particles, antioxidants, light stabilizers, and flame retardants that do not correspond to any of the components (A) and (B). Agents, flame retardant additives, chain transfer agents, etc., but are not limited by these. Examples of the (meth) acrylate compound that does not correspond to any of the (A) component and the (B) component include amine esters such as a 6-functional (meth) acrylate containing an amine ester bond. Acrylate.

In particular, from the viewpoints of light resistance and dicing property, the photocurable resin composition for a light guide of the present invention preferably contains the total amount of the component (A) and the component (B). It is 5 mole% or less of 6-functional (meth) acrylates containing amine ester bonds, or 6-functional (meth) acrylates containing amine ester bonds, and more preferably: 6 containing amine ester bonds Functional (meth) acrylate. The content of the 6-functional (meth) acrylate containing an amine ester bond is more preferably 3 mol% or less with respect to the total amount of the aforementioned (A) component and the aforementioned (B) component, and still more preferably relative to the aforementioned ( The total amount of the component A) and the component (B) is 2 mol% or less. When the content of the 6-functional (meth) acrylate containing an amine ester bond is suppressed within the above range or is not contained, there is a tendency that the light resistance can be improved and the discoloration due to light can be suppressed.

In addition, from the viewpoint of light resistance and dicing property, it is preferable that the photocurable resin composition for a light guide of the present invention does not contain only "6-functional" (meth) acrylate containing an amine ester bond. , And also does not contain (meth) acrylates containing amine ester bonds. Therefore, it can also be said that it is preferable to contain an amine ester bond-containing (meth) acrylate or not to contain an amine ester in an amount of 5 mol% or less based on the total amount of the component (A) and the component (B). The (meth) acrylate having a bond is more preferably free of a (meth) acrylate having an amine ester bond. In addition, the content of the (meth) acrylate containing an amine ester bond is more preferably 3 mol% or less with respect to the total amount of the component (A) and the component (B), and further more preferably relative to the aforementioned ( The total amount of the component A) and the component (B) is 2 mol% or less. When the content of the (meth) acrylic acid ester containing an amine ester bond is small, there is a tendency that the light resistance can be improved and the discoloration due to light can be suppressed. From the same viewpoint, it is also preferable that the photocurable resin composition for a light guide of the present invention does not contain a (meth) acrylate containing a nitrogen atom.

As the photopolymerization initiator, a conventional photopolymerization initiator that can be contained in a photocurable resin composition can be used. For example: fluorenyl phosphine oxide based photopolymerization initiator, aromatic ketone based photopolymerization initiator, quinone based photopolymerization initiator, alkylphenyl ketone based photopolymerization initiator, acridine based photopolymerization start Agent, phenylglycine-based photopolymerization initiator, coumarin-based photopolymerization initiator, oxime ester-based photopolymerization initiator, imidazole-based photopolymerization initiator, and the like. Among these, an alkylphenylketone-based photopolymerization initiator is preferred. The photopolymerization initiator may be used alone or in combination of two or more.

The refractive index of the scattering particles is different from a cured product of a photocurable resin composition for a light guide other than the scattering particles. The scattering particles have a function of changing the angle of light traveling through the light guide to scatter the light. As the scattering particles, for example, crosslinked polystyrene fine particles and the like can be mentioned. If it is a highly transparent material, plastic particles and glass particles of other materials can also be used. Among them, in order to scatter light, it is important to have a refractive index difference. It is preferable that the refractive index difference between the hardened | cured material of the photocurable resin composition for light guides other than this scattering particle, and a scattering particle is 0.005 or more. From the viewpoint of suppressing a decrease in light extraction efficiency and easily obtaining an effect of homogenizing light by scattering, the refractive index difference is preferably 0.005 to 0.015. Here, either the refractive index of the cured product of the photocurable resin composition for light guides other than the scattering particles or the refractive index of the scattering particles may be larger. The refractive index difference means the absolute value of the difference in refractive index between the two. The shape of the tritium scattering particles is not particularly limited, and a spherical shape is preferred. The average particle diameter of the thallium scattering particles is not particularly limited, but is preferably 0.5 to 5 μm, and more preferably 1.5 to 3.5 μm. By setting the average particle diameter of the scattering particles to 0.5 μm or more, it is possible to suppress a situation in which light is excessively scattered and the light extraction efficiency is reduced. In addition, by setting the average particle diameter of the scattering particles to 5 μm or less, a sufficient light diffusion effect can be obtained while maintaining a high light extraction efficiency.

The antioxidant is not particularly limited, and a phenol-based antioxidant is preferred. Rhenium is not particularly limited as a light stabilizer, and examples thereof include a hindered amine light stabilizer. Rhenium is not particularly limited as a flame retardant, and examples thereof include metal hydrates and phosphorus flame retardants. Rhenium is not particularly limited as a flame retardant additive, and examples thereof include inorganic flame retardant additives such as antimony trioxide and zinc molybdate. The chain transfer agent is not particularly limited, and examples thereof include 2-mercaptoethanol, laurylmercaptan, glycidylmercaptan, thioglycolic acid, 2-ethylhexyl thioglycolate, and 2,3-dimercapto-1- Thiol compounds such as propanol, 1,4-bis (3-mercaptobutyryloxy) butane, and pentaerythritol (3-mercaptobutyrate).

(Method for preparing light-curable resin composition for light guide) The method for preparing the light-curable resin composition for light guide of the present invention is not particularly limited, and the above-mentioned components can be prepared by mixing and stirring the components Photocurable resin composition for light body. Stirring is preferably performed at room temperature (about 5 to 30 ° C). Furthermore, the scattering particles may be mixed together when the components are mixed, and the components other than the scattering particles may be mixed and sufficiently stirred, and then the scattering particles may be mixed and stirred. Further, in order not to adversely affect the characteristics of the light guide, the photocurable resin composition for a light guide is preferably free of air bubbles. Thus, while not particularly limited, preferred are, for example: using ultrasonic cleaning at a frequency of 31 Hz to be processed 5 to 20 minutes, and further with a planetary mixer, a well around the number of 1,000 ~ 2,000 min ^{- 1,} since the number of around 60 ~ 100 min ^{- 1} to be stirred for 10 to 20 minutes for defoaming.

[Hardened Product for Light Guide] The hardened product obtained by curing the photocurable resin composition for a light guide of the present invention can be effectively used as a light guide. In other words, this invention also provides the hardened | cured material for light guides which hardened | cured the photocurable resin composition for light guides. (Manufacturing method of hardened | cured material for light guides) The manufacturing method of hardened | cured material for light guides is not specifically limited, A well-known manufacturing method can be used. Next, an example of the manufacturing method of the hardened | cured material for light guides is demonstrated. The material of the medium 8 described later, that is, the photocurable resin composition for a light guide of the present invention is introduced into a predetermined mold. At this time, at least one of the upper and lower surfaces of the mold is, for example, a transparent body such as glass in advance, so that an active energy ray can be previously irradiated to the photocurable resin composition for light guides from the outside. The light-curable resin composition for a light guide is hardened by irradiating active energy rays, and the hardened | cured material for a light guide can be manufactured. It can also be used directly as a light guide described later, and as described later, it can be used as a light guide by cutting the outer periphery of the hardened material appropriately to cut into a target shape and size. Hardening can use active energy rays. The active energy ray is not particularly limited, and examples thereof include ultraviolet rays, electron beams, α rays, and β rays. Among these, ultraviolet rays are preferred. When irradiating ultraviolet rays, its light source is preferably an ultraviolet irradiation device, which has, for example, a xenon lamp, a high-pressure mercury lamp, or a metal halide lamp. There are no particular restrictions on the hardening conditions. For example, when the standard of the thickness of the hardened material for the light guide is 1 mm, the exposure is preferably performed so that the exposure amount becomes 10 to 900 mJ / cm ² . Exposure is performed so that the amount becomes 50 to 150 mJ / cm ² .

[Light Guide] 硬化 The cured product for a light guide of the present invention can also be used directly as a light guide, and a cutting process can be appropriately performed to obtain a light guide of a desired shape and size. The cutting method is not particularly limited, and a general cutting processing device that can be used when manufacturing a light guide body such as a cutter can be used. Hereinafter, an example of the light guide of the present invention obtained by the above-mentioned method will be described with reference to the drawings. However, since the drawings are only schematic, the specific dimensions are not limited by the drawings.

An example of the light guide of the present invention will be described using FIGS. 1 to 5. The light guide 1 includes an incident surface 2 to which incident light 9 from a light source 7 (see FIG. 4) is incident, and an exit surface 3 to which incident light from the incident surface 2 is incident on the side surface 4. After propagating through the medium 8 included in the enclosed interior, the medium 8 is emitted from the emitting surface as the outgoing light 10; and the medium 8 is a hardened material for a light guide of the present invention. The light guide 1 has a function of efficiently emitting light (incident light 9) incident from the incidence surface 2 from the emission surface 3. Here, the term “good efficiency” means that the light extraction efficiency is good. The closer the ratio of the brightness of the emitted light 10 on the emitting surface 3 to the brightness of the incident light 9 on the incident surface 2 is, the better the efficiency is. The brightness refers to the brightness per unit area (cd / m ² ) when viewed from the normal direction of the entrance surface 2 or the exit surface 3. According to Snell's law, it is known that light with a larger incident angle than the critical angle cannot travel from medium 8 with high refractive index (inside light guide 1) to medium with low refractive index (inside air) ), And will be totally reflected. The side surface 4 has a function of confining light (not shown) incident from the incident surface 2 to the side surface 4 inside the light guide 1 by total reflection.

(Shape) As shown in FIG. 1, as an example of the outer shape of the light guide 1, for example, an approximate quadrangular prism having a length L, a width W, and a height H may be used, but is not limited thereto. The so-called approximate quadrangular prism means substantially a quadrangular prism, and although it includes a complete quadrangular prism, of course, it means that each side can be slightly shifted from completely parallel within a range in which the function of the light guide can be exhibited. The length L is not particularly limited, but preferably exceeds three times the width W or the height H. If the length L, that is, the optical path length is long, the probability that the light and the scattering particles 6 touch will increase. Therefore, it is easy to satisfy the color mixing property and uniformity by adjusting the filling rate of the scattering particles 6. When the length L is set to more than three times the width W, the efficiency can be maintained while maintaining the uniformity (color mixing and uniformity) of the emitted light 10 by adjusting to reduce the filling rate of the scattering particles 6. .

The incident surface 2 and the exit surface 3 are preferably approximately parallel. The reason is that at this time, light rays tend to be incident and emitted while maintaining the average angle of light that is incident perpendicularly, and an advantage in terms of efficiency can be expected. Here, the term “approximately parallel” means substantially parallel, and although it includes complete parallelism as a matter of course, it means that a slight deviation from perfect parallelism can occur within a range in which the function of the light guide can be exhibited. In addition, it is preferable that the incident surface 2 and the exit surface 3 have approximately the same shape. At this time, there is a tendency that light leakage on the side surface 4 can be reduced and reflection on the side surface 4 can be performed efficiently. The term “approximately the same shape” means that the shape is substantially the same, and although it includes the completely same shape, it means that the shape may be slightly shifted within a range in which the function of the light guide can be exhibited.

The height H and the width W of the incident surface 2 are preferably each equal to or larger than the length that can include the incident light 9. By setting in this way, the incident light 9 from the light source 7 will surely contact the incident surface 2, so it is possible to reduce the incident loss of light caused by the light not touching the incident surface 2 and not propagating in the light guide 1. .

The brightness of light emitted through the exit surface 3 is inversely proportional to the area of the exit surface 3. Therefore, for example, setting the area (emission area) of the exit surface 3 to be the same as the area (incident area) of a region of light incident on the incident surface 2 can reduce the The brightness of the exit surface 3 is reduced relative to the brightness of the entrance surface 2. In addition, compared with the case where the emission area is set to be larger than the incidence area, the sealing effect (the ratio of the luminance at the emission surface 3 to the luminance at the incidence surface 2) can be improved, and the color mixing effect can also be improved. Therefore, as compared with a case where the emission area is larger than the incidence area, the filling rate of the scattering particles 6 can be reduced and the efficiency can be further improved.

The side surface 4 preferably has a surface roughness (Ra) of about 1.0 μm or less. Reducing the surface roughness of the side surface 4 can reduce the leakage of light from the side surface 4 and can output a higher light amount. Here, the surface roughness (Ra) is an arithmetic average roughness specified in JIS B 0601 (2001).

(Light source) 光源 The light source 7 refers to a substance that generates light (incident light 9) to be incident on the incident surface 2 of the light guide 1. In FIGS. 4 and 5, a chip-type LED package 7 is used as the light source 7. The LED package 7 is a multi-chip light source, and is mounted in a frame to emit red, green, and blue wavelengths. The red LED chip 7a, the green LED chip 7b, and the blue LED chip 7c with the light.

The light in the red, green, and blue wavelength bands emitted from the light source 7 (see FIG. 4) is incident from the incident surface 2 of the light guide 1. If the red LED chip 7a, the green LED chip 7b, and the blue LED chip 7c mounted on the light source 7 are included in the inside of the contour of the incident surface 2, light will not leak out on the incident surface 2 and the efficiency will be good.

(Light Diffusion Means) In the light guide of the present invention, it is possible to adopt a state in which the exit light 10 emitted from the exit surface 3 is more uniform than the incident light 9 incident from the incident surface 2, that is, Can be used as an optical integrator. Herein, in the present invention, the "uniformization" means that the variation between the minimum brightness and the maximum brightness in the emission surface is reduced compared to the incidence surface. More specifically, it refers to a state in which when the ratio of the minimum brightness to the maximum brightness in a plane is set to B (B = minimum brightness / maximum brightness), the ratio of the minimum brightness to the maximum brightness in the aforementioned incident surface 2 B ₂ , and the ratio B ₃ between the minimum brightness and the maximum brightness in the exit surface 3 is B ₂ <B ₃ . The closer the B value is to 1, the more uniform the in-plane brightness is. In general, when 0.9 <B, the naked eye can easily feel uniform. As a method of making the emitted light 10 more uniform than the incident light 9, for example, a method of diffusing the incident light can be mentioned. As a method of diffusing light, for example, as shown in FIG. 2, a method in which a sheet-like diffuser 5 is provided on the outside of the exit surface 3 of the light guide 1; and the inside of the light guide 1 is provided. Method of light diffusion function. As the diffuser 5, a conventional light guide used in lighting can be used. As a method of imparting a light diffusion function to the inside of the light guide 1, for example, as shown in FIG. 3, a method of including the scattering particles 6 inside the light guide 1 may be mentioned. The scattering particles 6 are scattering particles described as components contained in a photocurable resin composition for a light guide. The light guide 1 is filled with scattering particles 6 as a medium having a refractive index different from that of the medium 8 other than the scattering particles 6 alone. According to Snell's law, when light passes through a medium with a different refractive index, it will exit at an angle different from the angle of incidence. The scattering particles 6 have a function of using this principle to change the angle of light traveling through the medium 8 and scatter the light. [Example]

Next, the present invention is described in more detail by the following examples, but these examples are not intended to limit the present invention in any sense. Using the cured product of the photocurable resin composition prepared in each example, each evaluation was performed according to the following method.

[Evaluation method] <1. Brightness reduction rate: light resistance> The brightness reduction rate was determined according to the following method, and it was set as an index of light resistance. The lower the brightness reduction rate, the higher the light resistance (LED light resistance). First, the brightness in the initial state was measured by the following method. As the light source, a chip-type LED "LTRB R8SF" (manufactured by OSRAM) was used. The red, green, and blue LED chips 7a, 7b, and 7c mounted in the LED package are arranged so as to include the incident surface 2 of the light guide obtained in each example. Set the anode as common, insert a 1 kΩ resistor between the ground and the red LED chip, insert a 150 Ω resistor between the ground and the blue LED chip, and insert no resistor between the ground and the green LED chip. 7 A voltage of 2.7 V was applied to emit light, and the front luminance of the light-emitting surface 3 of the light guide 1 was evaluated. The measurement was performed using a two-dimensional color distribution measuring device "CA-1500" (manufactured by KONICA MINOLTA Co., Ltd.). For the emission surface 3, the brightness data were measured with 121 equal divisions divided into 11 equal divisions in the width direction and 11 equal divisions in the height direction, and the average value of the measured frontal luminance at 121 points was set to the initial state. Brightness b1 (cd / m ² ). Then, the LED light was irradiated in the following method. As a light source, a wafer-type LED "OSTAR Stage LERTDUWS2W" (manufactured by OSRAM) was used. The white LED chip mounted on the LED package is arranged so as to be closely adhered to the incident surface 2 of the light guide. 3.45 V, 700 mA was applied to the wafer to emit light for 3 hours. Then, the brightness b2 (cd / m ² ) after irradiation was measured by the same method as the brightness measurement in the initial state, and the brightness reduction rate was calculated by the following formula (1). Brightness reduction rate (%) = ｛(b1-b2) / b1｝ × 100 (1)

<2. Elastic modulus> (Production of light guide for measuring elastic modulus) A center plate with a thickness of 2.0 mm is cut out with a length of 50 mm and a width of 35 mm as a spacer, and the glass plate is placed there. A gap having a length of 50 mm, a width of 35 mm, and a depth of 2 mm was made under the spacer, and a light-curable resin composition was introduced into the gap with the light guide, and then the glass plate was covered from above. At this time, it is performed so that air does not enter into the inside. Then, the photocurable resin composition for a light guide is sufficiently hardened by irradiating it with a UV (ultraviolet) lamp through a glass to obtain a cured product for a light guide. Using a cutter (DAC552, manufactured by DISCO Corporation), the obtained cured light guide was cut into a width of 25.0 mm and a length of 40.0 mm to obtain a light guide for measuring elastic modulus. (Measurement of Elastic Modulus) Use digital dynamometer "ZTS-50" (made by IMADA Co., Ltd.) and measuring stand "KV-50N-S" (made by IMADA Co., Ltd.) in accordance with JIS K7171 (2016) Method to measure the elastic modulus (MPa) of the light guide for measuring the elastic modulus.

<3. Cutability> Using a cutter (DAC552, manufactured by DISCO Co., Ltd.), the hardened material for light guides obtained in each example was cut into a width of 1.05 mm and a length of 4.15 mm with a cutter number of 4,800. During the cutting process, the spindle current value does not exceed 90% of the upper limit value, that is, 1.4 A, and when the cutting surface of the 20 light guides cut out is not observed, cracks and fragments of more than 100 μm cannot be observed. It is evaluated as cutting Good sex (A). Other cases were evaluated as poor dicing (B).

Hereinafter, each component used in an Example and a comparative example is demonstrated.

[(A) Ingredient]-(A1-1): "PE-200" (trade name, manufactured by Daiichi Kogyo Co., Ltd.), a bifunctional acrylate represented by the following formula

・ (A2-1): "FA-324A" (trade name, manufactured by Hitachi Chemical Co., Ltd.), a bifunctional acrylate represented by the following formula (containing an aromatic hydrocarbon group)

[(B) component]-(B1-1): "KAYARAD DPCA-20" (trade name, manufactured by Nippon Kayaku Co., Ltd.), a 6-functional acrylate represented by the following formula In the above formula, * ¹ means bonding to any one of *.

・ (B1-2): "KAYARAD DPCA-120" (trade name, manufactured by Nippon Kayaku Co., Ltd.), a 6-functional acrylate represented by the following formula In the above formula, * ¹ means bonding to any one of *.

・ (B1-3): "A-DPH" (trade name, manufactured by Shin Nakamura Chemical Industry Co., Ltd.), dipentaerythritol hexaacrylate (6-functional acrylate) represented by the following formula In the above formula, * ¹ means bonding to any one of *.

[Other ingredients] ・ Phenol-based antioxidant: "ADEKA STAB (registered trademark) AO-80" (manufactured by ADEKA Co., Ltd.)-Photopolymerization initiator 1: Alkyl phenone-based photopolymerization initiator "MICURE CP -4 "(Hydroxycyclohexylphenyl ketone, manufactured by Toyo Chemicals Co., Ltd.) ・ Photopolymerization initiator 2: Alkylphenylketone-based photopolymerization initiator" DAROCUR 1173 "(α-hydroxyα-methylbenzene Acetone, manufactured by BASF Japan Co., Ltd.)

The photocurable resin composition used in Comparative Example 1 was obtained in Production Example 1 below and included a 6-functional acrylate containing an amine ester bond. (Production Example 1) (2) A stirrer, a thermometer, a cooling tube, and an air introduction tube were attached to a 2 L three-necked flask. After air was introduced into this three-necked flask, pentaerythritol tri and tetraacrylate (manufactured by Toa Synthesis Co., Ltd., trade name: ARONIX M305) 113.32 g, polyethylene glycol 200 diacrylate (Daiichi Pharmaceutical Co., Ltd.) were added. (Product name: PE-200) 49.36 g, p-methoxybenzoquinone as a polymerization inhibitor 0.08 g, and catalyst dibutyltin dilaurate (manufactured by Tokyo Fine Chemical Co., Ltd., product name: L101) 0.05 g and warmed to 75 ° C. After heating, 40.5 g of hexamethylene diisocyanate (manufactured by Asahi Kasei Chemical Co., Ltd., trade name: DURANATE D-101) and polyethylene glycol 200 diacrylate (Daiichi Pharmaceutical Co., Ltd.) were added dropwise while stirring for 2 hours. Co., Ltd., trade name: PE-200) 26.6 g, and reacted. After the dripping was completed, after holding at 72 to 78 ° C. for about 4 hours, 9.5 g of polyethylene glycol 200 diacrylate (produced by Daiichi Kogyo Co., Ltd., trade name: PE-200) was poured. Then, 34.0 g of polyethylene glycol 200 diacrylate (made by Daiichi Kogyo Co., Ltd., trade name: PE-200) was added while the temperature was lowered to 40 to 60 ° C, and then phenol based was added at 40 to 60 ° C. Antioxidant (manufactured by ADEKA Co., Ltd., trade name: ADEKA STAB AO-80) 7.69 g, alkyl phenyl ketone photopolymerization initiator (manufactured by BASF Japan Co., Ltd., trade name: DAROCUR 1173) 11.5 g, light Polymerization initiator (hydroxycyclohexylphenyl ketone, manufactured by Toyo Chemicals Co., Ltd., trade name: MICURE CP-4) 11.5 g, polyethylene glycol 200 diacrylate (manufactured by Daiichi Kogyo Co., Ltd., trade name : PE-200) 418.9 g, modified ethylene oxide (EO) bisphenol A diacrylate (manufactured by Hitachi Chemical Co., Ltd., trade name: FA-324A) while maintaining heat while preparing a photocurable resin composition (For Comparative Example 1) containing a 6-functional acrylate containing an amine ester bond. Table 1 shows the components in this photocurable resin composition and their mass ratios (the numerical values in parentheses in Table 1 are mole ratios).

The photocurable resin composition used in Comparative Example 2 was obtained in the following Production Example 2 and contained a 6-functional acrylate containing an amine ester bond. (Production Example 2) (2) A stirrer, a thermometer, a cooling tube, and an air introduction tube were attached to a 2 L three-necked flask. After air was introduced into the three-necked flask, pentaerythritol tri and tetraacrylate (manufactured by Toa Synthesis Co., Ltd., trade name: ARONIX M305) 117.4 g, polyethylene glycol 200 diacrylate (Daiichi Pharmaceutical Co., Ltd.) were added. (Trade name: PE-200) 51.1 g, p-methoxybenzoquinone 0.09 g as a polymerization inhibitor, and dibutyltin dilaurate (manufactured by Tokyo Fine Chemical Co., Ltd., trade name: L101) 0.05 g and warmed to 75 ° C. After heating, 43.2 g of hexamethylene diisocyanate (manufactured by Asahi Kasei Chemicals Co., Ltd., trade name: DURANATE D-101) and polyethylene glycol 200 diacrylate (Daiichi Pharmaceutical Co., Ltd.) were added dropwise while stirring for 2 hours. Co., Ltd., trade name: PE-200) 27.6 g, and reacted. After completion of the dropping, heat was maintained at 72 to 78 ° C. for about 4 hours, and then 9.8 g of polyethylene glycol 200 diacrylate (produced by Daiichi Kogyo Co., Ltd., trade name: PE-200) was poured. Then, while the temperature was lowered to 40 to 60 ° C, 35.2 g of polyethylene glycol 200 diacrylate (produced by Daiichi Kogyo Co., Ltd., trade name: PE-200) was added, and then phenol based was added at 40 to 60 ° C. Antioxidant (made by ADEKA Co., Ltd., trade name: ADEKA STAB AO-80) 8.1 g, alkyl phenyl ketone-based photopolymerization initiator (made by BASF Japan Co., Ltd., trade name: DAROCUR 1173) 12.2 g, light Polymerization initiator (hydroxycyclohexylphenyl ketone, manufactured by Toyo Chemicals Co., Ltd., trade name: MICURE CP-4) 12.2 g, polyethylene glycol 200 diacrylate (manufactured by Daiichi Pharmaceutical Co., Ltd., trade name : PE-200) 433.8 g, modified ethylene oxide (EO) bisphenol A diacrylate (manufactured by Hitachi Chemical Co., Ltd., trade name: FA-324A) while maintaining heat while preparing a photocurable resin composition (For Comparative Example 2) containing a 6-functional acrylate containing an amine ester bond. Table 1 shows the components in this photocurable resin composition and their mass ratios (the numerical values in parentheses in Table 1 are mole ratios).

[Examples 1 to 13 and Comparative Examples 1 to 2] (Preparation of photocurable resin composition for light guide) In Examples 1 and 4 to 13, the descriptions in Table 1 were performed at room temperature (20 ° C). After each component was introduced into the reactor and fully stirred using a stirrer, cross-linked polystyrene microparticles (manufactured by Sekisui Chemical Industry Co., Ltd.) as scattering particles 6 were further added in an amount of 0.6% of the entire volume. , Trade name: Techpolymer (registered trademark) SSX-302ABE, approximately spherical, average particle size = about 2 μm, about 95% of the whole particles are monodisperse particles with a difference within 0.5 μm from the aforementioned average particle diameter), and stirred About 5 minutes, the photocurable resin composition for a light guide was prepared. On the other hand, in Examples 2 to 3, in accordance with the methods described in Production Examples 1 to 2, the contents of each component were adjusted and added appropriately so that the content of each component was as shown in Table 1 (B ) Component, while modulating the photocurable resin composition, the aforementioned crosslinked polystyrene fine particles were added so as to be 0.6% of the entire volume, and stirred for about 5 minutes to prepare a photocurable resin composition for a light guide. . In Comparative Examples 1 and 2, each of the crosslinked polystyrene fine particles was added to the photocurable resin composition obtained in the aforementioned Production Examples 1 and 2 so as to be 0.6% of the entire volume, and The light-curable resin composition for a light guide was prepared by stirring for about 5 minutes. Each of the above light guide body modulated light curable resin composition using the ultrasonic cleaner at a frequency of 31 Hz to 15 minutes, and further with a planetary mixer, a well around Number 1,500 min ^{- 1} (1,500 rpm), rotation speed 80 min ^{- 1} (80 rpm), and stirred for 15 minutes to defoam. Using the obtained photocurable resin composition for a light guide, the hardened | cured material for light guides was manufactured according to the said measuring method, and the elasticity modulus of this hardened | cured material was measured. (Manufacture of hardened body for light guide) A center plate with a thickness of 1.05 mm was cut into a length of 50 mm and a width of 7 mm as a spacer, and a glass plate was placed under the spacer to produce a length of 50 mm, After a gap having a width of 7 mm and a depth of 1.05 mm was introduced into the gap with a photocurable resin composition prepared by the method described above, the glass plate was covered from above. At this time, it is performed so that air does not enter into the inside. Then, the photocurable resin composition for a light guide is fully hardened by irradiating with a UV (ultraviolet) lamp through glass, and the hardened | cured material for light guides is obtained. Using this cured product for light guides, dicing properties were evaluated in accordance with the aforementioned method. The results are shown in Table 1. In addition, a cutter (DAC552, manufactured by DISCO Co., Ltd.) was used to cut the obtained light guide hardened product into a width of 1.05 mm and a length of 4.15 mm to obtain a light guide. At this time, the surface roughness (Ra) of the side surface 4 is 1.0 μm, and the surface roughness (Ra) of the light incident surface and the light exit surface is 2.0 μm. Using this light guide, light resistance was evaluated in accordance with the aforementioned measurement method. The results are shown in Table 1.

[Table 1]

As is clear from the results in Table 1, when the photocurable resin composition for a light guide of the present invention is used, even if an LED is used as a light source, the brightness reduction rate is extremely small, and it has very excellent light resistance. On the other hand, when the photocurable resin composition for a light guide of the comparative example is used, if an LED is used as a light source, the brightness reduction rate is large and the light resistance is insufficient. In addition, it was found that in Examples 1 to 6 and 11 to 13, the cured product had moderate flexibility and good cutting properties, and it was easy to produce a light guide having a desired size and shape. [Industrial availability]

The light guide of the present invention can be used for a light source device of a wearable terminal such as glasses or a watch, and particularly has an optical integrator used as the light source device.

1‧‧‧ light guide

2‧‧‧ incidence plane

3‧‧‧ exit surface

4‧‧‧ side

5‧‧‧ diffuser

6‧‧‧ scattering particles

7‧‧‧light source or LED package

7a‧‧‧Red LED Chip

7b‧‧‧Green LED Chip

7c‧‧‧Blue LED Chip

8‧‧‧ Medium

9‧‧‧ incident light

10‧‧‧ Emitted light

FIG. 1 is a schematic view (perspective view) showing an example of a light guide according to an embodiment of the present invention. (2) FIG. 2 is a schematic view (perspective view) showing an example in which a diffusion function is provided to the exit surface side of the light guide. FIG. 3 is a schematic view (perspective view) showing an example of imparting a diffusion function to the inside of the light guide. FIG. 4 is a schematic view (perspective view) showing a positional relationship between a light source and a light guide. Fig. 5 is a schematic view (front view) showing Fig. 4 as viewed from the light emitting surface side.

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Claims (20)

A light-curable resin composition for a light guide, comprising: (A) 2-functional (meth) acrylate; and, (B) 6-functional (meth) acrylate, which contains or does not contain an oxygen atom. It is composed of an aliphatic hydrocarbon group (b1) and a (meth) acrylfluorenyl group (b2). The photocurable resin composition for a light guide according to claim 1, wherein in the content ratio of the component (A) and the component (B), the total number of functional groups of the component (A) is relative to the component ( B) The total number of functional groups of the component, that is, (A) / (B) is 1.1 to 8. The photocurable resin composition for light guides according to claim 1 or 2, wherein in the content ratio of the component (A) to the component (B), the total number of functional groups of the component (A) is relative to The total number of functional groups of the aforementioned (B) component, that is, (A) / (B) is 1.3 to 5. The photocurable resin composition for light guides according to any one of claims 1 to 3, wherein in the content ratio of the component (A) and the component (B), a total of the component (A) The number of functional groups is 1.3 to 3.60, that is, the total number of functional groups of the component (B), that is, (A) / (B). The photocurable resin composition for a light guide according to any one of claims 1 to 4, further comprising 5 mol% or less based on the total amount of the component (A) and the component (B). 6-functional (meth) acrylates with or without amine ester linkages. The photocurable resin composition for a light guide according to any one of claims 1 to 5, which does not contain a 6-functional (meth) acrylate containing an amine ester bond. The photocurable resin composition for a light guide according to any one of claims 1 to 6, wherein the component (A) contains a bifunctional (methyl) group including a structure represented by the following formula (A1) Acrylate: In the formula (A1), m ¹ is an integer of 1 to 10, and * represents a site bonded to another group. The photocurable resin composition for light guides according to any one of claims 1 to 7, wherein the component (A) contains a bifunctional (methyl) group including a structure represented by the following formula (A2) Acrylate: In formula (A2), n ¹ and n ² are each independently an integer of 1 to 5 and satisfy 2 ≦ n ¹ + n ² ≦ 10, X is a linking group containing an aromatic hydrocarbon group, and * represents a group bonded to other groups. Parts. The photocurable resin composition for light guides as described in any one of Claims 1-8 whose molecular weight of the said (A) component is 150-700. The photocurable resin composition for light guides according to any one of claims 1 to 9, wherein the component (A) contains a bisphenol modified from a polyethylene glycol diacrylate and ethylene oxide. At least one selected from the group consisting of A diacrylate. The photocurable resin composition for light guides according to any one of claims 1 to 10, wherein the component (A) contains polyethylene glycol diacrylate and ethylene oxide modified bisphenol A di Acrylate. The light-curable resin composition for a light guide according to claim 11, wherein the content ratio of the ethylene oxide modified bisphenol A diacrylate to the polyethylene glycol diacrylate is epoxy. The ethane-modified bisphenol A diacrylate / polyethylene glycol diacrylate has a molar ratio of 0.40 or less. The photocurable resin composition for light guides according to any one of claims 1 to 12, wherein the component (B) includes a structure represented by the following formula (B1): In the formula (B1), * represents a site bonded to another group. The photocurable resin composition for light guides as described in any one of Claims 1-13 whose molecular weight of the said (B) component is 350-3,000. The photocurable resin composition for light guides according to any one of claims 1 to 14, wherein the component (B) is composed of the following compounds (B1-1) to (B1-3) At least one selected from the group: In the above formulae (B1-1) to (B1-3), * ¹ represents a bond with any one of the *, and R ² is a hydrogen atom or a methyl group; in a compound, a plurality of R ² may be the same or different. . A cured product for a light guide, which is obtained by curing the photocurable resin composition for a light guide according to any one of claims 1 to 15. The cured product for light guides according to claim 16, wherein the elastic modulus is 400 to 1,000 MPa. A light guide has: (i) an incident surface from which incident light from a light source is incident; (ii) an exit surface from which the incident light incident from the aforementioned incident surface propagates through a medium provided therein, and is emitted as light from the The emitting surface emits; and the medium is a hardened material for a light guide according to claim 16 or 17. The light guide according to claim 18, wherein the exit light emitted from the exit surface is more uniform than the incident light after entering from the incident surface. An optical integrator composed of the light guide according to claim 18 or 19.