Illumination device and storage shelf

Abstract

To provide a lighting device that has a certain light diffusivity and also can add a certain flexibility to a lighting cover.SOLUTION: A lighting device 10 is equipped with a light source 11 and a lighting cover 12 that is disposed so as to cover the light source 11 and has an air bubble containing layer 13 having air bubbles inside.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a lighting device and a storage shelf provided with the lighting device.

Background Art

[0002] Conventionally, lighting devices using light sources such as fluorescent lamps and incandescent lamps have been common. In recent years, however, LED lighting devices using LED light-emitting elements have been widely put into practical use because of their long lifespan and low power consumption. The lighting device is often used as illumination light after being diffused by a cover member with high light diffusibility. For example, Patent Document 1 discloses that a cover provided to face an LED light-emitting element has diffusibility and is formed of a translucent resin such as a polycarbonate resin or an acrylic resin.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, the cover formed of the translucent resin described in Patent Document 1 needs to be blended with light diffusing particles or the like for imparting light diffusibility. In addition, since the cover formed of a conventional translucent resin is generally formed of a hard material, a certain space is required for installing the cover, and the space constraint is also large.

[0005] Furthermore, in recent years, lighting devices have been considered for installation not only on the ceiling surface but also in various locations in the living space. However, lighting devices installed on parts other than the ceiling surface may be collided with by users in daily life. Conventionally, covers made of a translucent resin are generally hard and can cause relatively significant pain to users when collided with, making it difficult to use them with a sense of security.

[0006] Therefore, an object of the present invention is to provide a lighting device that has a certain light diffusing property without blending an additive for light diffusion such as light diffusing particles in a lighting cover, and can also impart a certain flexibility to the lighting cover.

Means for Solving the Problems

[0007] As a result of intensive studies, the inventors of the present invention have found that the above problems can be solved by using a bubble-containing layer having bubbles inside as a lighting cover, and have completed the following present invention. That is, the present invention has the following gists [1] to

[16] . [1] A lighting device including a light source and a lighting cover disposed so as to cover the light source and having a bubble-containing layer having bubbles inside. [2] The lighting device according to [1] above, wherein the bubble-containing layer is a foam. [3] The lighting device according to [1] or [2] above, wherein the lighting cover further includes a surface layer, and the bubble-containing layer and the surface layer are arranged in this order from the light source side. [4] The lighting device according to any one of [1] to [3] above, wherein the total light transmittance of the bubble-containing layer is 0.3% or more. [5] The lighting device according to any one of [1] to [4] above, wherein at least a part of the light source is arranged so as to be embedded inside the bubble-containing layer. [6] The lighting device according to any one of [1] to [5] above, wherein the light source includes an LED. [7] The lighting device according to any one of [1] to [6] above, wherein the light source includes a plurality of light-emitting elements and a base sheet, and the plurality of light-emitting elements are arranged on the base sheet. [8] The lighting device according to any one of [1] to [7] above, comprising a reflective layer, wherein the reflective layer is provided on the side opposite to the side where the lighting cover of the light source is provided. [9] The lighting device according to any one of [1] to [8] above, which is disposed in a recess provided in a part of a ceiling, a wall surface, or a floor surface.

[10] The lighting device according to any one of [1] to [8] above, which is suspended and disposed from a ceiling.

[11] A storage shelf including the lighting device according to any one of [1] to [8] above.

[12] The storage shelf according to

[11] above, wherein the lighting device is attached to at least one of a shelf board and a side board of the storage shelf.

[13] The storage shelf according to

[11] or

[12] above, wherein a part of the shelf board is pulled out to form a workbench of a desk.

[14] The storage shelf according to

[11] or

[12] above, which is a storage shelf disposed on a desk.

[15] The storage shelf according to

[14] above, wherein the lighting device is attached to a shelf board disposed on the upper surface of the desk.

[16] The storage shelf according to

[14] or

[15] above, comprising a shelf board disposed on the upper surface of the desk and a side board over which the shelf board is bridged, and the lighting device is attached to the side board. [Effect of the Invention]

[0008] According to the present invention, it is possible to provide a lighting device that has a certain light diffusibility and can also impart a certain flexibility to the lighting cover without blending an additive for light diffusion such as light diffusing particles in the lighting cover. [Brief Description of the Drawings]

[0009]

Figure 1

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Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Embodiments for Carrying Out the Invention

[0010] <Lighting Device> In the present invention, the lighting device includes a light source and a lighting cover that is arranged to cover the light source and has a bubble-containing layer having bubbles inside.

[0011] [Light Source] The light source used in the present invention may be any light source used as the light source of a lighting device such as a fluorescent lamp, an incandescent lamp, an LED, or an organic EL element. Among these, LEDs and organic EL elements are preferred, and among them, LEDs are more preferred. LEDs are also referred to as light-emitting diodes or inorganic LEDs.

[0012] As the LED, it is preferable to use a point light source composed of an LED chip or the like. The point light source LED has high light linearity, but by using a lighting cover having a bubble-containing layer, appropriate light diffusion can be achieved as described later. In addition, the point light source has a small thickness and can also make the lighting device thin. Note that the shape of the LED, which is a point light source, is not particularly limited and may be, for example, a square or any other shape. Also, the size of the LED, which is a point light source, is not particularly limited. For example, the area may be about 5 cm 2 or less, or about 1 cm 2 or less, or about 1 cm 2 or less, and for example, it may be 0.001 cm 2 or more, or 0.005 cm 2 or more.

[0013] Also, as the light source, a plurality of light-emitting elements arranged side by side may be used. For example, a plurality of LEDs may be arranged side by side and used. Specifically, for example, the light-emitting elements may be arranged linearly, or may be arranged in any form such as a checkerboard pattern or a staggered pattern. Also, the light source may be a light source sheet in which a plurality of light-emitting elements are arranged on a sheet. Among them, an LED sheet in which a plurality of LEDs are arranged on a base sheet is preferable. Each LED in the LED sheet is usually the above-described point light source. By using a light source sheet such as an LED sheet, a lighting device capable of irradiating a relatively large area can be obtained with a simple configuration. Also, when an organic EL element is used as the light source, a sheet-like organic EL element may be used as the light source sheet.

[0014] The base sheet used for the light source sheet is preferably a resin film, but other than a resin film may be used. The base film may have transparency or may be a colored film or the like. By using a colored film as the base sheet, the light from the light-emitting element can be reflected, making it easier to emit the light as illumination light to the front side where the lighting cover is provided. The colored film is preferably colored in a color with a relatively high reflectance such as white, light color, or metallic color. Among them, a white film is preferable.

[0015] [Lighting Cover] The lighting cover is arranged to cover the above-described light source and includes a bubble-containing layer. In the present invention, since the lighting cover includes the bubble-containing layer, the light from the light source can be diffused by the bubbles, enabling uniform and uneven-free lighting. In addition, a light source with high light linearity such as an LED tends to have local brightness, and there is also a risk of eye damage when directly viewing the light source. However, in the present invention, even when using a light source with high light linearity, by using a lighting cover having a bubble-containing layer, the light from the light source can be diffused, enabling uniform and uneven-free lighting. Furthermore, as will be described later, by adjusting the foaming ratio and the like to appropriately adjust the degree of diffusion in the bubble-containing layer, even a light source that emits highly linear light such as an LED can be made into soft light such as indirect lighting, thus creating a comfortable space.

[0016] The lighting cover may be composed of the bubble-containing layer alone, but in addition to the bubble-containing layer, it is preferably provided with a surface layer. When the surface layer is provided, in the lighting cover, the bubble-containing layer and the surface layer are preferably arranged in this order from the light source side. The lighting cover (that is, the bubble-containing layer or the laminate of the bubble-containing layer and the surface layer) may be appropriately formed into a desired shape. Examples of the forming method include vacuum forming, compression molding, stamping molding, and the like.

[0017] <Bubble-containing layer> The bubble-containing layer used for the lighting cover is preferably composed of a foam. By making the bubble-containing layer a foam, bubbles uniformly formed inside can be easily contained. In addition, it is easy to ensure flexibility and easy to deform, so the space constraints for installing the lighting cover are reduced. Also, the touch becomes soft and it is easy to give the user a sense of security. The thickness of the bubble-containing layer is, for example, 6 mm or less, preferably 5 mm or less, more preferably 4 mm or less, and is, for example, 0.1 mm or more, preferably 0.5 mm or more, more preferably 1 mm or more. By setting the thickness of the bubble-containing layer within the above range, it becomes easier to diffuse the light from the light source in the bubble-containing layer, and it also becomes easier to irradiate the light from the light source to the outside through the lighting cover.

[0018] (Total light transmittance) The total light transmittance of the bubble-containing layer is, for example, 0.3% or more. By setting the total light transmittance of the bubble-containing layer to 0.3% or more, the lighting cover is made light-transmissive, and it becomes easier to emit a certain amount or more of the light emitted from the light source to the outside. The total light transmittance of the bubble-containing layer is preferably 5% or more, more preferably 10% or more, still more preferably 20% or more, and even more preferably 30% or more. Also, from the perspective of light transmittance, the higher the total light transmittance of the bubble-containing layer, the better. However, from the perspective of facilitating the enhancement of light diffusibility, it may be, for example, 95% or less, 90% or less, or 85% or less.

[0019] (Haze value) The haze value of the bubble-containing layer is preferably 60% or more. By setting the haze value of the bubble-containing layer to 60% or more, it becomes easier to diffuse the light from the light source with the lighting cover. From the perspective of light diffusibility, the haze value is preferably 70% or more, more preferably 80% or more, and still more preferably 90% or more. The upper limit of the haze value is not particularly limited, but from the perspective of light transmittance, it may be less than 100%. The total light transmittance and the haze value can be within the above ranges by appropriately adjusting the expansion ratio, resin components, compounds formulated in the resin, etc. The total light transmittance can be measured using a haze meter in accordance with ASTM D1003. Also, the haze value can be measured using a haze meter in accordance with ASTM D1003.

[0020] (Apparent density) In the present invention, the apparent density of the bubble-containing layer is preferably 0.025 to 0.60 g / cm 3 . When the apparent density of the bubble-containing layer is within the above range, while improving light transmittance, a certain flexibility and mechanical strength are imparted. Also, the haze value can be easily adjusted within a desired range. From these viewpoints, the apparent density is more preferably 0.05 to 0.50 g / cm 3 , even more preferably 0.10 to 0.40 g / cm 3 , still more preferably 0.10 to 0.33 g / cm 3 .

[0021] <25% Compressive Strength> The 25% compressive strength of the bubble-containing layer is preferably 10 to 2500 kPa. When the 25% compressive strength is equal to or less than the above upper limit value, the flexibility of the bubble-containing layer is improved, and it can be deformed into various shapes with fewer restrictions on the space for installing the lighting cover. Also, it is easier to give users a sense of security. On the other hand, by setting it to be equal to or greater than the lower limit value, the mechanical strength of the bubble-containing layer becomes good. From these viewpoints, the 25% compressive strength of the bubble-containing layer is more preferably 30 to 2000 kPa, even more preferably 50 to 1500 kPa, and still more preferably 80 to 900 kPa. Note that the 25% compressive strength is a value measured by a measurement method based on JIS K6767.

[0022] <Expansion Ratio> When the bubble-containing layer is a foam, the expansion ratio of the foam is preferably 1.3 to 40 times, more preferably 1.5 to 20 times, even more preferably 2 to 15 times, and still more preferably 3 to 10 times. When the expansion ratio is equal to or greater than the above lower limit value, the foam is appropriately foamed, and while the light transmittance is improved, the flexibility is also good. On the other hand, although the light transmittance tends to improve as the expansion ratio increases, it is preferably equal to or less than the above upper limit value in order to ensure mechanical strength. Note that the expansion ratio can be calculated by dividing the density of the foam before foaming by the density (apparent density) of the foam after foaming.

[0023] The resin constituting the foam is not particularly limited, and various types of resins can be used. Specifically, urethane resins, acrylic resins, polyolefin resins, polystyrene resins, various elastomers, rubber components, etc. can be used, and among these, polyolefin resins are preferred. By using polyolefin resins, appropriate flexibility and mechanical strength can be imparted to the foam sheet. Also, from the viewpoint of facilitating foaming, the resin is preferably a thermoplastic resin.

[0024] The foam may be one formed by foaming a foamable composition containing a resin, but it is preferably one formed by foaming a foamable composition containing at least a polyolefin resin, and more preferably one formed by crosslinking and foaming a foamable composition containing a polyolefin resin. Examples of polyolefin resins include polyethylene resins, polypropylene resins, ethylene-vinyl acetate copolymers, etc., and from the viewpoint of flexibility, among these, polyethylene resins are preferred.

[0025] <Crosslinking degree (gel fraction)> The foam of the present invention is preferably crosslinked as described above, and its crosslinking degree (gel fraction) is preferably 10 to 70% by mass. When the gel fraction is at least the above lower limit value, sufficient crosslinking is formed in the foam, so the mechanical strength tends to be high. Also, when the crosslinking degree is at most the above upper limit value, it becomes easier to ensure the flexibility etc. of the foam. From such a viewpoint, the crosslinking degree is more preferably 15 to 60% by mass, and still more preferably 20 to 55% by mass.

[0026] Hereinafter, the foam (polyolefin resin foam) in the case of using a polyolefin resin as the resin constituting the foam will be described in more detail.

[0027] [Polyolefin resin foam] The polyolefin resin foam of the present invention is a polyolefin resin foam formed by foaming a polyolefin resin composition containing a polyolefin resin. In addition, in the polyolefin resin foam, it is preferable that the polyolefin resin is the main component. Specifically, the content of the polyolefin resin is preferably 65% by mass or more based on the total amount of the resin components contained in the polyolefin resin composition. In the polyolefin resin foam using the polyolefin resin as the main component, generally, the light transmittance tends to decrease. However, in the present invention, by appropriately adjusting the foaming ratio, resin components, compounds blended in the resin, etc., a polyolefin resin foam excellent in total light transmittance can be obtained.

[0028] <Polyolefin resin> As the polyolefin resin, at least one selected from polyethylene resin, polypropylene resin, and ethylene-vinyl acetate copolymer is preferable. These resins may be used alone or in combination of two or more. The polyolefin resin foam of the present invention preferably has a polyolefin resin as the main component. Specifically, the content of the polyolefin resin is preferably 65% by mass or more based on the total amount of the resin components contained in the polyolefin resin composition. When the content of the polyolefin resin is 65% by mass or more, it becomes easier to ensure the mechanical strength, flexibility, etc. of the foam. Also, as will be described later, it becomes easier to use one type of polyolefin resin as the main component resin. From these viewpoints, the content of the polyolefin resin is preferably 70 to 100% by mass, more preferably 75 to 100% by mass, based on the total amount of the resin components contained in the foam resin composition. Hereinafter, the total amount of the resin components contained in the polyolefin resin composition will be simply referred to as "based on the total amount of the resin components".

[0029] ≪Polyethylene resin≫ As the polyethylene resin, low-density polyethylene resin (0.93 g / cm 3 Hereinafter, LDPE), medium-density polyethylene resin (greater than 0.930 g / cm 3 and less than 0.942 g / cm 3 MDPE), high-density polyethylene resin (0.942 g / cm 3Examples of the above include HDPE. In addition, preferred specific examples of the low-density polyethylene resin include linear low-density polyethylene resin (LLDPE).

[0030] Among these, linear low-density polyethylene resin and high-density polyethylene resin are preferred, and linear low-density polyethylene resin is more preferred. By using these resins, it is easier to lower the rate of change in the compression strength of the foam. Note that the density of the linear low-density polyethylene resin is preferably 0.90 g / cm 3 or more, more preferably 0.91 g / cm 3 or more and 0.93 g / cm 3 or less. Also, the density of the high-density polyethylene resin is preferably 0.98 g / cm 3 or less, more preferably 0.95 g / cm 3 or more and 0.97 g / cm 3 or less. By setting the density of the high-density polyethylene resin and the linear low-density polyethylene resin within these ranges, it is easier to lower the compression strength and the like without impairing the flexibility of the foam.

[0031] The polyethylene resin may be a homopolymer of ethylene, or may be a copolymer of ethylene and a small amount of α-olefin with ethylene as the main component (preferably 75% by mass or more, more preferably 90% by mass or more of all monomers). Examples of the α-olefin preferably have 3 to 12 carbon atoms, more preferably 4 to 10 carbon atoms, and specifically include 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-octene, and the like. In the copolymer, these α-olefins can be used alone or in combination of two or more. Also, the polyethylene resin may be used alone or in combination of two or more.

[0032] ≪Polypropylene resin≫ As the polypropylene resin, homopolypropylene which is a homopolymer of propylene may be used, or a copolymer of propylene and a small amount of ethylene and an α-olefin other than propylene with propylene as the main component (preferably 75% by mass or more, more preferably 90% by mass or more of all monomers) etc. may be mentioned. Examples of the copolymer of propylene and an α-olefin other than ethylene and propylene include block copolymers (block polypropylene), random copolymers (random polypropylene), random block copolymers etc. Examples of the α-olefin other than propylene include α-olefins having about 4 to 10 carbon atoms such as 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-octene etc. Among these, ethylene is preferable from the viewpoints of moldability and heat resistance. In the copolymer, these α-olefins can be used alone or in combination of two or more. Further, the polypropylene resin may be used alone or two or more kinds may be used in combination.

[0033] In the present invention, any of polyethylene resin, polypropylene resin, or a mixture thereof polymerized with a polymerization catalyst such as a Ziegler-Natta compound, a metallocene compound, a chromium oxide compound etc. may be used. By using a polyethylene resin, particularly linear low density polyethylene obtained by a polymerization catalyst of a metallocene compound, it becomes easy to obtain a foam having high flexibility.

[0034] ≪Ethylene-vinyl acetate copolymer≫ Examples of the ethylene-vinyl acetate copolymer used as the polyolefin-based resin include ethylene-vinyl acetate copolymers containing 50% by mass or more of structural units derived from ethylene. Since the ethylene-vinyl acetate copolymer has high compatibility with polyethylene resin and polypropylene resin, the light transmittance of the foam is improved by using in combination the ethylene-vinyl acetate copolymer and one or more selected from polyethylene resin and polypropylene resin. The density of the ethylene-vinyl acetate copolymer is preferably 0.92 g / cm3 More preferably, it is 0.93 g / cm or more 3 Still more preferably, it is 0.94 g / cm or more 3 or more, and preferably 0.97 g / cm or less 3 More preferably, it is 0.96 g / cm or less 3 By setting the density of the ethylene-vinyl acetate copolymer within these ranges, it becomes easier to lower the compression strength and the like without impairing the flexibility of the foam.

[0035] In the present invention, it is preferable to use any one of the above-described polyolefin resins as the main component resin. Here, the main component resin means that any one of the polyolefin resins is contained in an amount of 65% by mass or more based on the total amount of the resin components. Therefore, it is preferable to contain any one of polypropylene resin, polyethylene resin, or ethylene-vinyl acetate copolymer in an amount of 65% by mass or more. Generally, when two or more resins are blended, the resins do not mix completely with each other and cloudiness occurs due to the blending. However, in the present invention, by using a specific single resin (i.e., a single resin component) as the main component resin, cloudiness due to blending is less likely to occur and the light transmittance of the foam is enhanced.

[0036] Among the above-described resins, the resin used as the main component resin is preferably either polypropylene resin or polyethylene resin, and more preferably polypropylene resin. By using polypropylene resin as the main component resin, the foam has excellent heat resistance and can be used for a long period even when heated by a light source. More specifically, when using polypropylene resin as the main component resin, it is advisable to contain the polypropylene resin in an amount of 65% by mass or more based on the total amount of the resin components, preferably 75% by mass or more, more preferably 85% by mass or more, and most preferably 100% by mass. Also, preferably, among the polypropylene resins, a specific type of resin is contained in an amount of 65% by mass or more based on the total amount of the resin components. For example, block polypropylene may be 65% by mass or more, or random polypropylene may be 65% by mass or more. In this case as well, these specific types of resin are preferably contained in an amount of 75% by mass or more, more preferably 85% by mass or more, and most preferably 100% by mass.

[0037] Similarly, when using a polyethylene resin as the main component resin, it is preferable to contain the polyethylene resin in an amount of 65% by mass or more based on the total amount of the resin components, preferably 75% by mass or more, and more preferably 85% by mass or more. Also, preferably, among the polyethylene resins, a specific type of resin is contained in an amount of 65% by mass or more based on the total amount of the resin components. For example, LDPE may be 65% by mass or more. In this case as well, these specific types of resin are preferably 75% by mass or more, and more preferably 85% by mass or more.

[0038] When using a polypropylene resin as the main component resin, as a polyolefin resin, the polypropylene resin may be used alone, but in addition to the polypropylene resin, at least one selected from a polyethylene resin and an ethylene-vinyl acetate copolymer may be used in combination. When the polypropylene resin is used alone, there is no need to compatibilize it with other polyolefin resins, so a decrease in transparency due to mixing of the resins is prevented. Also, by using in combination the polypropylene resin and at least one selected from an ethylene-vinyl acetate copolymer and a polyethylene resin, the compatibility becomes good and the transparency is maintained well. Furthermore, since it becomes easier to adjust the degree of crosslinking and the expansion ratio, it becomes easier to adjust the total light transmittance of the foam. In this case, based on the total amount of the resin components, the content of the polypropylene resin is preferably 65 to 95% by mass, and at least one selected from a polyethylene resin and an ethylene-vinyl acetate copolymer is preferably 5 to 35% by mass. Also, the former being 75 to 95% by mass and the latter being 5 to 25% by mass is more preferable, and the former being 85 to 95% by mass and the latter being 5 to 15% by mass is even more preferable. Moreover, the resin to be used in combination is preferably either a polyethylene resin or an ethylene-vinyl acetate copolymer, and more preferably an ethylene-vinyl acetate copolymer. When using a polypropylene resin as the main component resin, an elastomer may be further used as described later. The content of the elastomer in this case is as described later.

[0039] On the other hand, when using a polyethylene resin as the main component resin, as a polyolefin resin, in addition to the polyethylene resin, at least one selected from a polypropylene resin and an ethylene-vinyl acetate copolymer may be used in combination, but it is preferable to use the polyethylene resin alone. However, when using the polyethylene resin alone, it is preferable to further use the elastomer described later, and the content of the elastomer at that time is as described later.

[0040] The resin constituting the polyolefin-based resin foam may be composed of only the polyolefin-based resin, or may be a mixture of the polyolefin-based resin and an elastomer. By including an elastomer in the polyolefin-based resin composition, the crystallinity of the polyolefin-based resin can be lowered, and the total light transmittance of the foam is improved. That is, in the present invention, it is preferable to use an elastomer that functions as a so-called clarifying agent. Moreover, by using an elastomer, the flexibility and impact absorbency of the foam can be improved.

[0041] As the elastomer, an elastomer having good compatibility with the polyolefin-based resin is used, and specifically, ethylene-propylene-diene rubber (EPDM), ethylene-propylene rubber (EPM), styrene rubber, etc. are exemplified. Moreover, thermoplastic elastomers are also exemplified as the elastomer. Examples of the thermoplastic elastomer include olefin-based thermoplastic elastomers and styrene-based thermoplastic elastomers. The elastomer may be used alone or in combination of two or more of the above components. From the viewpoint of easily adjusting the total light transmittance of the foam within the above range, styrene rubber, olefin-based thermoplastic elastomer, and styrene-based thermoplastic elastomer are preferable, and among them, styrene rubber and styrene-based thermoplastic elastomer are more preferable.

[0042] Examples of the styrene rubber include various polymers such as a random copolymer of styrene and a conjugated diene compound, and its hydrogenated product may also be used. Specifically, styrene-butadiene copolymer (SBR), or its hydrogenated product (HSBR), etc. may be mentioned.

[0043] Examples of the olefin-based thermoplastic elastomer include a blend type and a dynamic crosslinking type. More specifically, there are thermoplastic elastomers using a thermoplastic crystalline polyolefin such as polypropylene or polyethylene for the hard segment and a fully vulcanized or partially vulcanized rubber for the soft segment. Examples of the soft segment component include butyl rubber, halobutyl rubber, EPDM, EPM, acrylonitrile / butadiene rubber, NBR, natural rubber, etc., and EPDM is preferably used. In addition, the olefin-based thermoplastic elastomer also includes a block copolymer type. Examples of the block copolymer type include those having a crystalline block and a soft segment block. More specifically, crystalline olefin block-ethylene·butylene copolymer-crystalline olefin block copolymer (CEBC) is exemplified. In CEBC, the crystalline olefin block is preferably a crystalline ethylene block, and examples of commercially available products of such CEBC include "DYNARON 6200P" manufactured by JSR Corporation, etc.

[0044] Examples of the styrene-based thermoplastic elastomer include block copolymers having a polymer or copolymer block of styrene and a polymer or copolymer block of a conjugated diene compound. Examples of the conjugated diene compound include isoprene, butadiene, etc. The styrenic thermoplastic elastomer used in the present invention may or may not be hydrogenated. When hydrogenation is carried out, it can be performed by a known method.

[0045] The styrenic thermoplastic elastomer is usually a block copolymer, and examples thereof include styrene-isoprene block copolymer, styrene-isoprene-styrene block copolymer, styrene-butadiene block copolymer, styrene-butadiene-styrene block copolymer, styrene-ethylene / butylene-styrene block copolymer (SEBS), styrene-ethylene / propylene-styrene block copolymer (SEPS), styrene-ethylene / butylene block copolymer (SEB), styrene-ethylene / propylene block copolymer (SEP), styrene-ethylene / butylene-crystalline olefin block copolymer (SEBC), and the like. Among the above-mentioned styrenic thermoplastic elastomers, block copolymers are preferred, and among them, SEBC is more preferred. By using such an elastomer in combination with a polyolefin resin and further adjusting the foaming ratio, it becomes possible to improve the light transmittance of the foam.

[0046] Examples of commercially available styrenic thermoplastic elastomers include "DYNARON 1320P" (styrene content: 10% by mass), manufactured by JSR Corporation, "DYNARON 8600P" (styrene content: 15% by mass), and "DYNARON 4600P" (styrene content: 20% by mass).

[0047] In the present invention, when a polyolefin resin and an elastomer are used in combination as the resin component, the content of the elastomer is preferably 5 to 30% by mass, more preferably 8 to 22% by mass, based on the amount of the resin component. If the content of the elastomer is within these ranges, the light transmittance of the foam can be further improved while maintaining the mechanical strength of the foam.

[0048] <Foaming agent> The polyolefin-based resin foam of the present invention is obtained by foaming a resin composition containing a polyolefin-based resin and a foaming agent. As the foaming agent, a thermal decomposition type foaming agent is preferred. As the thermal decomposition type foaming agent, organic foaming agents and inorganic foaming agents can be used. Examples of the organic foaming agent include azo compounds such as azodicarbonamide, metal salts of azodicarboxylic acid (such as barium azodicarboxylate), azobisisobutyronitrile, nitroso compounds such as N,N'-dinitrosopentamethylenetetramine, hydrazodicarbonamide, hydrazine derivatives such as 4,4'-oxybis(benzenesulfonylhydrazide) and toluenesulfonylhydrazide, semicarbazide compounds such as toluenesulfonyl semicarbazide, and the like. Examples of the inorganic foaming agent include ammonium carbonate, sodium carbonate, ammonium bicarbonate, sodium bicarbonate, ammonium nitrite, sodium borohydride, monosodium anhydrous citrate, and the like. Among these, from the viewpoints of obtaining fine bubbles, economy, and safety, azo compounds are preferred, and azodicarbonamide is more preferred. The thermal decomposition type foaming agent may be used alone or in combination of two or more.

[0049] The content of the foaming agent in the polyolefin-based resin composition is preferably 1 to 30 parts by mass, more preferably 2 to 25 parts by mass, and even more preferably 2 to 20 parts by mass with respect to 100 parts by mass of the polyolefin-based resin. By setting the blending amount of the foaming agent to 1 part by mass or more, the resin composition can be moderately foamed, and appropriate flexibility and shock absorbency can be imparted to the foam. Also, by setting the blending amount of the foaming agent to 30 parts by mass or less, it is possible to prevent the foam from foaming more than necessary and to improve the mechanical strength and the like of the foam.

[0050] <Additive> The polyolefin-based resin composition may contain components such as a nucleating agent, a crosslinking aid, a decomposition temperature adjuster, and an antioxidant.

[0051] <Nucleating agent> As the nucleating agent used in the present invention, there is no particular limitation as long as it has the effect of improving the progress rate of the crystal nucleation process. By adding a nucleating agent to a polyolefin resin such as a polyethylene resin or a polypropylene resin, the size of the resulting crystals can be reduced, thereby improving the transparency of the foam. As the nucleating agent used in the present invention, substances having the effect of promoting molecular chain orientation through the adsorption process of the polymer molecular chain and having the effect of improving the progress rate of the crystal nucleation process can be mentioned. More specifically, high melting point polymers, organic carboxylic acids or their metal salts, aliphatic alcohol groups, dibenzylidene sorbitol or its derivatives, partial metal salts of rosin acid, amide compounds, inorganic fine particles, organic phosphoric acid compounds or their metal salts, imides, quinacridones, quinones, aromatic sulfonates or their metal salts, saccharides, and mixtures thereof can be mentioned. These may be used alone or in combination of two or more.

[0052] When using a nucleating agent in the present invention, the content of the nucleating agent in the polyolefin resin composition is preferably 0.5 to 10 parts by mass, more preferably 1.5 to 8 parts by mass, and even more preferably 2 to 7 parts by mass with respect to 100 parts by mass of the polyolefin resin. When the content of the nucleating agent is at least the lower limit value, the transparency of the foam is improved. On the other hand, when the content of the nucleating agent is at most the upper limit value, the transparency of the foam can be improved while suppressing the production cost. The polyolefin resin composition of the present invention may have both a nucleating agent and an elastomer, but it is preferably to have either one of them. By having either one of them, the light transmittance can be effectively improved.

[0053] As the crosslinking aid, a polyfunctional monomer can be used. By adding a crosslinking aid to the polyolefin resin, the amount of ionizing radiation irradiated in step (2) described later is reduced, and the cleavage and degradation of resin molecules accompanying the irradiation of ionizing radiation are prevented. Specific examples of the crosslinking aid include compounds having three functional groups in one molecule, such as trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, triallyl trimellitate, triallyl 1,2,4-benzenetricarboxylate, and triallyl isocyanurate; compounds having two functional groups in one molecule, such as 1,6-hexanediol dimethacrylate, 1,9-nonanediol dimethacrylate, 1,10-decanediol dimethacrylate, and divinylbenzene; and diallyl phthalate, diallyl terephthalate, diallyl isophthalate, ethyl vinylbenzene, neopentyl glycol dimethacrylate, lauryl methacrylate, stearyl methacrylate, and the like. These crosslinking aids may be used alone or in combination of two or more.

[0054] The addition amount of the crosslinking aid is preferably 0.5 to 10 parts by mass, more preferably 1.0 to 8 parts by mass, and still more preferably 1.5 to 5 parts by mass with respect to 100 parts by mass of the polyolefin resin. By setting the addition amount to 0.5 part by mass or more, it becomes possible to stably obtain the desired degree of crosslinking of the foam, and by setting it to 10 parts by mass or less, it becomes easy to control the degree of crosslinking of the foam.

[0055] A decomposition temperature regulator may be blended in the polyolefin resin composition. The decomposition temperature regulator is blended to lower the decomposition temperature of the thermal decomposition type foaming agent, increase the decomposition rate, or adjust it. Specific examples of the compound include zinc oxide, zinc stearate, urea, and the like. The decomposition temperature regulator is blended in an amount of, for example, 0.01 to 5 parts by mass with respect to 100 parts by mass of the polyolefin resin in order to adjust the surface state of the foam and the like.

[0056] An antioxidant may be incorporated into the polyolefin resin composition. Examples of the antioxidant include phenolic antioxidants such as 2,6-di-t-butyl-p-cresol and pentaerythritol tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], sulfur antioxidants such as dilauryl thiodipropionate, phosphorus antioxidants, and amine antioxidants. The antioxidant is incorporated in an amount of 0.01 to 5 parts by mass, for example, per 100 parts by mass of the polyolefin resin. In addition to these, additives generally used for foams such as heat stabilizers, colorants, flame retardants, antistatic agents, and fillers may be incorporated into the polyolefin resin composition.

[0057] [Method for producing foam] Although there is no particular limitation on the method for producing the polyolefin resin foam, it can be produced by heating a foamable sheet composed of a polyolefin resin composition containing at least a resin and a thermal decomposition type foaming agent to cause the thermal decomposition type foaming agent to foam. More specifically, the production method preferably includes the following steps (1) to (3). Step (1): A step of forming a foamable sheet composed of a polyolefin resin composition containing at least a resin and a thermal decomposition type foaming agent Step (2): A step of irradiating the foamable sheet with ionizing radiation to crosslink the foamable sheet Step (3): A step of heating the crosslinked foamable sheet to cause the thermal decomposition type foaming agent to foam to obtain a foam

[0058] In step (1), the method for forming the foamable sheet is not particularly limited. For example, the resin and additives may be supplied to an extruder, melt-kneaded, and the polyolefin resin composition may be extruded in a sheet form from the extruder for forming. Alternatively, the foam may be formed by pressing the polyolefin resin composition. The forming temperature of the foamable sheet (i.e., the temperature during extrusion or the temperature during pressing) is preferably 50°C or higher and 250°C or lower, more preferably 80°C or higher and 180°C or lower.

[0059] As a method for crosslinking the polyolefin resin composition in step (2), a method of irradiating the foaming sheet with ionizing radiation such as electron beams, α-rays, β-rays, γ-rays, etc. is used. The irradiation dose of the above ionizing radiation may be adjusted so that the crosslinking degree of the obtained foam falls within the above-mentioned desired range, but it is preferably 1 to 12 Mrad, and more preferably 1.5 to 8 Mrad.

[0060] In step (3), when heating the polyolefin resin composition to foam the thermally decomposable foaming agent, the heating temperature may be equal to or higher than the foaming temperature of the thermally decomposable foaming agent, but is preferably 200 to 300 °C, and more preferably 220 to 280 °C.

[0061] Also, in this manufacturing method, the foam may be stretched in either one or both of MD or TD. The stretching of the foam may be performed after obtaining the foam by foaming the foaming sheet, or may be performed while foaming the foaming sheet. When stretching the foam after obtaining the foam by foaming the foaming sheet, the foam may be continuously stretched while maintaining the molten state during foaming without cooling the foam, or after cooling the foam, the foam may be heated again to a molten or softened state and then the foam may be stretched. The foam becomes easier to make thinner by stretching. Also, when stretching the foam, the foam may be heated to, for example, 100 to 280 °C, preferably 150 to 260 °C. In the present invention, by stretching the foam, the cell diameter of the foam becomes larger along either one or both of MD or TD, and the light transmittance tends to be higher.

[0062] However, this manufacturing method is not limited to the above, and foams may be obtained by methods other than the above. For example, instead of irradiating with ionizing radiation, an organic peroxide may be previously blended in the polyolefin resin composition, and crosslinking may be performed by a method such as heating the foaming sheet to decompose the organic peroxide. Also, in the production of the foam of the present invention, the obtained foam may be sliced to obtain a foam having a desired thickness.

[0063] [Surface layer] As described above, it is preferable to provide a surface layer on the surface side of the foam (i.e., the side opposite to the side where the light source is provided). By providing the surface layer, the foam is not exposed on the surface, so that the design property of the lighting cover can be enhanced. Note that the surface layer may also be called a surface decorative sheet or the like. Specific examples of the surface layer used for the lighting cover include resin sheets such as polyvinyl chloride sheets, mixed resins of polyvinyl chloride and ABS resins, and thermoplastic elastomer sheets, woven fabrics, knitted fabrics, non-woven fabrics using natural fibers or artificial fibers, and leather such as artificial leather and synthetic leather. Among these, a resin sheet is preferable as the surface layer.

[0064] The surface layer may be appropriately provided with unevenness of a geometric pattern or the like, or printing or the like may be applied to the surface. Further, from the viewpoint of preventing damage, various coatings may be applied to the surface of the surface layer. As the unevenness, from the viewpoint of enhancing the design property, a embossed pattern or the like formed on the surface of the surface layer may be used. Also, a silicone stamper or the like with unevenness transferred from genuine leather, stone, wood, etc. may be used to attach a leather grain or wood grain pattern or the like to the surface of the surface layer. The printing applied to the surface of the surface layer is not particularly limited, and may be, for example, wood grain-like or leather-like printing.

[0065] It is preferable to use a surface layer having light transmissivity. By having light transmissivity, the light emitted from the light source can be appropriately irradiated to the outside through the bubble-containing layer and the surface layer. The total light transmittance of the surface layer is, for example, 0.3% or more, preferably 1% or more, more preferably 5% or more, and still more preferably 10% or more in order to enhance the light emission efficiency from the light source. Also, in order to make the bubble-containing layer such as the foam difficult to be visually recognized from the outside, the total light transmittance of the surface layer is, for example, 80% or less, preferably 60% or less, more preferably 50% or less, and still more preferably 40% or less.

[0066] The thickness of the surface layer is not particularly limited. For example, it is 0.08 to 5 mm, preferably 0.1 to 2 mm, and more preferably 0.2 to 1 mm. By setting the thickness of the surface layer within these ranges, while improving the mechanical strength of the surface layer, high light transmittance and the like can also be ensured. Also, by increasing the thickness of the surface layer, it is possible to prevent the interior such as the foam from being seen through.

[0067] The surface layer may be bonded to the bubble-containing layer. Examples of methods for bonding the surface layer to the bubble-containing layer include, for example, the extrusion lamination method, the adhesive lamination method in which an adhesive is applied and then bonded, the thermal lamination method (heat fusion method), the hot melt method, the high-frequency welder method, and the like. Also, the surface layer may be bonded to the bubble-containing layer with an adhesive, an adhesive tape, etc., but both may be bonded by any method.

[0068] The lighting cover of the present invention may have layers other than the above-described surface layer such as a printing layer and the bubble-containing layer. For example, by providing a printing layer on the outermost surface of the lighting cover (for example, the surface of the surface layer, or the surface of the foam when the surface of the surface layer is not provided), the design property of the lighting cover can be enhanced. Also, a light-shielding region where illumination light is not transmitted may be provided by the printing layer. As a method for forming the printing layer, a known method such as the inkjet method can be appropriately used.

[0069] In the present invention, even when providing the surface layer as described above, it is preferable to have a total light transmittance of a certain level or more. Therefore, the transmittance of the lighting cover may be any value as long as it is a certain level or more. The total light transmittance of the lighting cover may be, for example, 0.3% or more in order to increase the light emission efficiency from the light source, but preferably 1% or more, more preferably 5% or more, and even more preferably 10% or more. Also, the total light transmittance of the lighting cover may be, for example, 95% or less, 80% or less, 50% or less, or 30% or less. Incidentally, as described above, the lighting cover has a printed layer provided on the surface layer and the bubble-containing layer, and there is a region where the total light transmittance is partially reduced. In such a case, it means the total light transmittance of the region where the total light transmittance of the lighting cover is maximized. Incidentally, the total light transmittance of the lighting cover can be adjusted by the thickness, composition, etc. of the surface layer and the bubble-containing layer.

[0070] The specific configuration of the lighting device of the present invention will be described in more detail with reference to FIGS. 1 to 4. In the following description, the case where a light source sheet is used as the light source 11 is exemplified, but the light source is not limited to the light source sheet. Also, in FIGS. 1 to 4, an example in which the lighting cover includes a surface layer and a bubble-containing layer is shown, but the surface layer may be omitted as appropriate. As shown in FIG. 1, the lighting device 10 includes, for example, a light source 11 and a lighting cover 12, and may be arranged such that the lighting cover 12 is laminated on the surface of the light source 11, for example. Also, the lighting cover 12 may have a laminated structure in which a bubble-containing layer 13 and a surface layer 14 are arranged in this order from the light source 11 side.

[0071] (Reflection layer) Also, the lighting device may have a reflection layer. As shown in FIG. 2, the reflection layer 16 may be provided on the back side of the light source 11, that is, on the side opposite to the side where the lighting cover 12 is provided. When the reflection layer 16 is provided, stray light radiated from the light source to the back side is reflected by the reflection layer 16 and emitted to the front side, and the light emission efficiency of the light from the light source in the lighting device becomes good. The reflection layer is not particularly limited, but for example, a colored film or a colored plate is used. The colored film is preferably colored in a color with a relatively high reflectance such as white, light color, or metallic color, and among them, a white film is preferable. The colored plate is preferably colored in a color with a relatively high reflectance such as white, light color, or metallic color, and among them, a white plate is preferable. As the colored film, a known colored film may be used. For example, a resin film containing a colorant such as titanium oxide, silicon dioxide, or calcium carbonate is used. Also, examples of the colored plate include a resin plate containing a colorant. Note that the reflective layer 16 is effective when the light from the light source 11 is radiated to the back side. For example, when the light source 11 is a light source sheet, it is effective to use it when the base sheet constituting the light source sheet has light transmissivity.

[0072] The above-described reflective layer is not particularly limited, but it is preferably bonded to the light source. The reflective layer may be bonded to the light source using, for example, an adhesive or an adhesive tape. Further, when the reflective layer is a resin film, it may be bonded to the light source by, for example, an extrusion lamination method, an adhesive lamination method in which an adhesive is applied and then bonded, a thermal lamination method (heat fusion method), a hot melt method, a high-frequency welder method, etc., but it may be bonded to the light source by any method.

[0073] Further, the reflective layer 16 may be a coating film formed on the back surface of the light source (for example, a light source sheet), or a coating film formed on the front side of a heat dissipation layer composed of a metal plate, a graphite sheet, etc., which will be described later. The coating film may be, for example, a colored layer, and may be a layer formed by applying an ink containing a coloring agent. Specific examples of the coloring agent are as described above.

[0074] (Heat dissipation layer) Further, the lighting device may have a heat dissipation layer. As shown in FIG. 3, the heat dissipation layer 17 is preferably provided on the back side of the light source 11, that is, on the side opposite to the side where the lighting cover 12 is provided. The heat dissipation layer 17 is a layer formed of a material having high thermal conductivity, and may be, for example, a metal layer composed of a metal plate such as an aluminum plate or a stainless steel plate, or a layer other than a metal layer such as a graphite sheet. Further, when the heat dissipation layer is composed of a metal layer, it also functions as a reflective layer. When the heat dissipation layer 17 is provided in the lighting device 10, the heat dissipation layer 17 may be provided together with the reflective layer 16. In this case, as shown in FIG. 4, it is preferably provided in the order of the reflective layer 16 and the heat dissipation layer 17 from the light source 11 side. The heat dissipation layer 17 is not particularly limited, but it is preferably bonded to the back surface of the light source (such as a light source sheet) or the reflective layer using, for example, an adhesive or an adhesive tape.

[0075] FIG. 5 shows an example of a specific example of a laminated structure of an LED sheet and a bubble-containing layer when the light source is an LED sheet. As shown in FIG. 1, the LED sheet 20 includes a base sheet 21 and a plurality of LEDs 22 provided on one surface of the base sheet 21. Further, typically, the bubble-containing layer 13 is laminated on the LED sheet 20. However, since the bubble-containing layer 13 has flexibility as described above, it is compressed and deformed at the portion where the LEDs 22 are provided, and the LEDs 22 are arranged so as to be embedded inside the bubble-containing layer 13. Thus, in the present invention, by arranging a part of the light source to be embedded inside the bubble-containing layer 13, the lighting device can be made thinner. In the above description, an example in which an LED sheet is used as the light source has been described. However, even in the case other than the LED sheet, at least a part of the light source such as a light-emitting element may be embedded, and in the present invention, it is not always necessary for at least a part of the light source to be embedded inside the bubble-containing layer 13.

[0076] <Usage method> The lighting device of the present invention can be used for various applications. For example, it is provided on the ceiling and used for lighting indoors and the like. The lighting device provided on the ceiling may be a so-called embedded type. The embedded lighting device is a lighting device provided in a recess provided in a part of the ceiling. Since the lighting device of the present invention can be made thin by using a light source sheet such as an LED sheet, when it is an embedded type, the lighting device can be installed inside a relatively shallow recess. The embedded lighting device can be made into a highly designed lighting device by arranging the surface (for example, the surface layer) of the lighting cover on the same plane as the ceiling surface.

[0077] In addition, the lighting device provided on the ceiling is not limited to the embedded type, and may be a suspended type. The suspended lighting device is one that suspends the above lighting device from the ceiling surface using a jig or the like. However, the lighting device provided on the ceiling is not limited to the embedded type and the suspended type, and any type may be used. For example, the lighting device may be attached to the ceiling surface other than the recess without being suspended. The lighting device of the present invention may be provided other than on the ceiling. For example, it may be provided on a wall surface, a floor surface, or the like. The lighting device provided on a wall surface, a floor surface, or the like may be an embedded type disposed in a recess provided in a part of the wall surface or the floor surface, but may also be other than the embedded type.

[0078] The lighting device of the present invention may be other than those attached to and used on a ceiling surface, a wall surface, a floor surface, etc., and may be attached to a part other than the ceiling surface, the wall surface, and the floor surface of a building, particularly a residential building. Further, the lighting device may be attached to and used on furniture or the like. The lighting device is not particularly limited, but may be attached to furniture, a ceiling surface, a wall surface, a floor surface, or other parts by any fixing means such as an adhesive tape, an adhesive, or a screw.

[0079] Among them, it is preferable that the lighting device is attached to and used on a storage shelf. The storage shelf may be any type of storage shelf, but typically has a shelf board arranged along the horizontal direction. Further, the storage shelf typically also has side plates arranged along the vertical direction, and the shelf board may be spanned between the side plates. Also, the topmost shelf board may be referred to as a top board, and the lowermost shelf board may be referred to as a bottom board. Generally, the storage shelf stores stored items such as clothes, books, daily necessities, and foodstuffs thereon. The storage shelf may be any type of storage shelf, such as a bookshelf, a clothes storage shelf, a food storage shelf, or the like. Further, the storage shelf may be a storage shelf provided on a desk or the like.

[0080] FIG. 6 shows a first embodiment of a storage shelf. In this embodiment, the storage shelf is a storage shelf 50 provided on a desk. The storage shelf 50 includes a shelf board 52 disposed on the upper surface (desk surface) of the desk 51, and the shelf board 52 is spanned between both side plates 53, 53 provided on the upper surface of the desk 51. In this embodiment, the lighting device 10 is attached to the front end surface 52A of the shelf board 52. The lighting device 10 can be made thin and does not protrude more than the front end surface 52A, so it does not give a sense of pressure to the user and also has excellent design. Here, the shelf board 52 to which the lighting device 10 is attached is a shelf board arranged at a position close to the upper surface of the desk 51. The upper surface of the desk 51 can be illuminated by the lighting device 10 attached to the front end surface 52A of the shelf board 52 and can be effectively used as hand-held lighting. Furthermore, by providing the lighting device 10 with a flexible bubble-containing layer, the touch feeling can be soft and a sense of security can be given to the user.

[0081] FIG. 7 shows a second embodiment of a storage shelf provided on a desk. The storage shelf 60 shown in FIG. 7 includes a plurality of shelf boards 62, 62, and further includes side plates 63, 63 across which the shelf boards 62 are spanned. The side plates 63, 63 are attached to the upper surface of the desk 51. Also, the storage shelf 60 is provided with a back plate 64 on the back side, but the back plate 64 may be omitted as appropriate. In the present embodiment, as shown in FIG. 7, the lighting device 10 is arranged on the front end surface 62A of the shelf board 62 arranged at the position closest to the desk among the plurality of shelf boards 62. Also, the lighting device 10 is provided on the front end surface 63A of the side plate 63. Note that the lighting device 10 provided on the front end surface of the side plate 63 is arranged in the lower portion of the side plate 63 in the present embodiment. The lower portion of the side plate 63 is, for example, a portion below the shelf board 62 arranged at the position closest to the desk and is a portion connecting the shelf board 62 and the upper surface of the desk 51.

[0082] Also in the present embodiment, the lighting device 10 can be made thin and, even when attached to the front end surfaces 62A, 63A, does not protrude more than the front end surfaces 62A, 63A and can be made excellent in design. Also, by arranging the lighting device at the lower portions of the front end surface 62A of the shelf board 62 and the front end surface 63A of the side plate 63, which are close to the upper surface of the desk 51, the upper surface of the desk 51 can be appropriately illuminated. Furthermore, by providing the lighting device 10 with a flexible bubble-containing layer, the touch feeling can be soft and a sense of security can be given to the user.

[0083] Note that the storage shelf in which the lighting device is provided on at least one of the front end surfaces of the side plate and the shelf board as described above is not limited to the storage shelf provided on the desk and can be any storage shelf. In addition, in the above-described second embodiment, the position where the lighting device 10 is arranged is an example and is not limited to the above-described arrangement position. For example, the lighting device may be arranged on the inner surface of the shelf board 62, the inner surface of the side board 63, or on the front surface of the back board 64. Even in such a case, the shelf board 62, the side board 63, and the back board 64 on which the lighting device is arranged are not particularly limited. However, in order to appropriately illuminate the upper surface of the desk 51, among the plurality of shelf boards 62, it is preferable that the shelf board 62 is arranged at the position closest to the desk (desk surface), or the side board 63 or the back board 64 in the portion below the shelf board 62 arranged at the position closest to the desk.

[0084] FIG. 8 shows another form (third embodiment) of the storage shelf. The storage shelf 70 in this embodiment is box-shaped, and both side plates 73, 73, the top plate 75, and the bottom plate 76 respectively constitute the side surface, the top surface, and the bottom surface of the storage shelf 70. Further, the storage shelf 70 is provided with a back board 74 that constitutes the back surface. Also, a shelf board 72 is provided, and the shelf board 72 is spanned between both side plates 73, 73. The storage shelf 70 is not particularly limited, but may be a fixed type or a movable type with casters. Also, the storage shelf 70 is generally provided with a door (not shown) that can be opened and closed on the front surface.

[0085] In the storage shelf 70, as shown in FIG. 8, the lighting device 10 is provided, for example, on the inner surfaces of both side plates 73, the top plate 75, and the bottom plate 76 (that is, both side surfaces, the top surface, and the bottom surface) respectively. The storage shelf 70 is box-shaped and the inside is likely to become dark. However, by providing the lighting device 10 on the inner surface, the inside of the storage shelf 70 can be appropriately illuminated. Also, the lighting device 10 is small in size and does not protrude more than the inner surface of the storage shelf. Therefore, even when provided on the inner surface of the storage shelf 70, there is no sense of oppression and the storage space is not made smaller than necessary, and it is also excellent in design. Furthermore, the touch is soft and can give the user a sense of security.

[0086] Also, in the present embodiment, the lighting device 10 is disposed on the front side of the inner surface (i.e., both side surfaces, the top surface, and the bottom surface). By being disposed on the front side in this way, it becomes easier to appropriately illuminate with low power consumption in a place where it is difficult for the user to visually recognize. And the lighting device 10 disposed on the front side is preferably disposed so as to extend along the circumferential direction inside the storage shelf 70, whereby the inside of the storage shelf 70 can be illuminated from both sides and vertically and horizontally.

[0087] However, the position where the lighting device 10 is disposed is not particularly limited, and it may be provided on substantially the entire surface of each of the both side surfaces, the top surface, and the bottom surface. Also, as shown in FIG. 9, the lighting device 10 may be disposed so as to extend in the depth direction (i.e., the front-rear direction). In this case, for example, it may be disposed at the four corners of the storage shelf 70 (i.e., the connection portion or its vicinity between the side plate and the top surface, and the connection portion or its vicinity between the side plate and the top surface). Also, as shown in FIG. 10, the storage shelf may be provided with a partition plate 77 provided along the vertical direction.

[0088] Also, the storage shelf may be provided with a lighting device on a portion other than the side surface, the top surface, and the bottom surface. For example, as shown in FIG. 11, the lighting device may be attached to the main surface of the partition plate 77 or the main surface of the shelf board 72 other than the top surface and the bottom surface. By attaching the lighting device 10 to the partition plate 77 and the shelf board 72 as well, as shown in FIG. 11, each space partitioned by the shelf board 72 and the partition 77 can be appropriately illuminated by the lighting device 10. When the lighting device 10 is attached to the partition plate 77 or the shelf board 72, the position where the lighting device 10 is attached is not particularly limited. However, as shown in FIG. 11, in relatively large spaces S1, S2, it may be provided at the four corners. Also, in relatively small spaces S3 to S6, instead of being provided at the four corners, for example, the lighting device 10 may be provided on both sides so as to sandwich each space, and the space may be illuminated from both sides. Of course, although not shown, the lighting device 10 may be provided above and below the space to illuminate the space from above and below, or other modes may be used. Further, for example, as shown in FIG. 12, for each space formed by being partitioned into a plurality, it may be arranged to extend along the circumferential direction of each space so as to surround substantially the entire circumference. Thereby, each space is more likely to be appropriately illuminated by the lighting devices provided on both sides and above and below. In the box-shaped storage shelf described above, the lighting device may be provided on the inner surface of the back plate 74 or the like in addition to the above.

[0089] Note that the storage shelves shown in FIGS. 8 to 12 may be of a type in which at least a part of the shelf boards including the top board and the bottom board are pulled out in front of other shelf boards to form a workbench (desk surface) of a desk. The shelf board may be slid and pulled out forward to become a desk surface, or a folded one may be pulled out to become a desk surface, or a board leaned against the back plate may be set to become a desk surface. In this case, the lighting device provided on the storage shelf may irradiate the desk surface. In that case, the arrangement position of the lighting device that irradiates the desk surface may be the same as the arrangement position when the storage shelf is provided on the desk as described in the second embodiment.

[0090] Also, in the third embodiment shown in FIGS. 8 to 12, an example of a box-shaped storage shelf is shown, but it is not limited to the box-shaped storage shelf. For example, a building, particularly a residential building, has a storage part called a closet or the like, and a lighting device may be provided on the inner surface of the storage part. For example, the inner surface of the storage part generally has side surfaces, a top surface, a bottom surface, and a back surface, similar to the storage shelf shown in FIGS. 8 to 12, and a lighting device may be provided on any one or all of these inner surfaces. Also, in the storage part, any of the modes shown in FIGS. 8 to 12 can be adopted. Therefore, in the storage part, the lighting device may be provided on the front side of the inner surface of the storage space as shown in FIG. 8, or may be arranged to extend inward as shown in FIG. 9, or may be arranged in other modes. In addition, the storage section does not necessarily have to be a storage shelf, and it may be one without a shelf board or a partition board. Further, when a storage shelf or a partition board is provided in the storage section, as shown in FIGS. 11 and 12, a lighting device may be provided on the shelf board or the partition board.

[0091] Then, in a box-shaped storage shelf or storage section, the lighting device may be attached in any manner as long as it is attached to at least one of the inner surfaces of both side surfaces, the top surface, the bottom surface, and the back surface, and the main surfaces of the partition board and the shelf board. In addition, in the storage shelf, as shown in the first and second embodiments, while being attached to the front end surface of the side plate or the shelf board, as shown in the third embodiment, it may be attached to at least one of the inner surfaces of both side surfaces, the top surface, the bottom surface, and the back surface, and the main surfaces of the partition board and the shelf board.

Example

[0092] The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples in any way.

[0093] [Measurement method] The measurement methods for each physical property in this specification are as follows. <Apparent density> The apparent density of the foam was measured in accordance with JIS K7222:2005. <Expansion ratio> The expansion ratio was calculated by dividing the density of the foamable sheet before foaming by the density (apparent density) of the foam after foaming.

[0094] <Degree of crosslinking (gel fraction)> An approximately 100 mg test piece was taken from the foam sheet, and the weight A (mg) of the test piece was precisely weighed. Next, this test piece was immersed in 30 cm of xylene at 120°C 3 and left for 24 hours, then filtered through a 200-mesh wire mesh to collect the insoluble matter on the wire mesh, vacuum-dried, and the weight B (mg) of the insoluble matter was precisely weighed. From the obtained values, the degree of crosslinking (mass %) was calculated by the following formula. Degree of crosslinking (mass %) = (B / A) × 100

[0095] <25% Compressive Strength> The 25% compressive strength was measured by a measurement method conforming to JIS K6767.

[0096] <Total Light Transmittance> The total light transmittance of the foam was measured using a haze meter for the foam adjusted to the thickness described in Table 1 in accordance with ASTM D1003.

[0097] <Illumination Light Evaluation> An LED light source, which is a point light source, was arranged above the irradiated table, and light from the LED light source was irradiated onto the irradiated table through an illumination cover arranged so as to be in contact with the lower side of the LED light source, and the maximum diameter S2 of the region where the light was irradiated on the irradiated table was measured. Also, with the illumination cover removed, the maximum diameter S1 of the region where the light was irradiated on the irradiated table was measured in the same manner. When the following formula holds, it was evaluated as "A" assuming that the light diffusibility of the illumination cover is good, and when it does not hold, it was evaluated as "B". In the following formula, h represents the distance between the light source and the irradiated table. S2 > S1 + h × tan20°

[0098] <Flexibility Evaluation> Regarding the illumination covers of each example and comparative example, the flexibility was evaluated according to the following evaluation criteria by touch. A: High flexibility, easily deformed, and the touch is soft, giving a sense of security to the user. B: Low flexibility, unable to be deformed, and the touch is hard, not giving a sense of security to the user.

[0099] <Raw Materials Used> The materials used in the examples shown in Table 1 are as follows. 〔Polyolefin Resin〕 PP: "Noblen AD571" manufactured by Sumitomo Chemical Co., Ltd. (Density: 0.900 g / cm 3 ) LLDPE: "Nipolon-Z ZF231B" of Tosoh Corporation (Density: 0.917 g / cm 3 ) EVA(1): Tosoh Corporation's "Ultra Senn 636" (density: 0.941 g / cm 3 ) EVA(2): Tosoh Corporation's "Ultra Senn 710" (density: 0.949 g / cm 3 )

[0100] 〔Elastomer〕 HSBR: JSR Corporation's "DYNARON 1320P"

[0101] Nucleating agent: Saccharide-based, Tokyo Ink Co., Ltd.'s "NAT-95" Blowing agent: Eiwa Kasei Co., Ltd.'s "AC#R" (azodicarbonamide) Crosslinking aid: Kyoeisha Chemical's "Light Ester 1.9-ND" (1,9-nonanediol dimethacrylate) Antioxidant: BASF Japan's "Irganox 1010"

[0102] Example 1 80 parts by mass of polypropylene resin (PP), 19 parts by mass of polyethylene resin (LLDPE), 2 parts by mass of nucleating agent, 8 parts by mass of blowing agent, 3 parts by mass of crosslinking aid, and 0.8 parts by mass of antioxidant were melt-kneaded and then pressed to obtain a foaming sheet with a thickness of 0.3 mm. Electron beams were irradiated on both sides of the obtained foaming sheet at an acceleration voltage of 500 keV at 3 Mrad to crosslink the foaming sheet. Next, the crosslinked foaming sheet was heated to 250 °C to foam it, obtaining a foam with an apparent density of 0.09 g / cm 3 , a thickness of 1.0 mm. The obtained foam was used as a lighting cover for various evaluations. The evaluation results are shown in Table 1.

[0103] Examples 2 to 5 The formulation of the polyolefin-based resin composition was changed as shown in Table 1, and the electron beam irradiation dose was adjusted to achieve the crosslinking degree shown in Table 1, and then the procedure was the same as in Example 1. The obtained foam was used as a lighting cover for various evaluations. The evaluation results are shown in Table 1.

[0104] <Comparative Example 1> A commercially available diffuser plate (product name: "Sumipex", manufactured by Sumitomo Chemical Co., Ltd.) was used as the lighting cover instead of the foam for various evaluations.

[0105]

Table 1

[0106] In each example of the present invention, by using a foam, which is a bubble-containing layer, as the lighting cover, it was possible to improve flexibility, appropriately diffuse light in the lighting cover, and transmit a certain amount or more of light through the lighting cover. On the other hand, although the diffuser plate used as a conventional lighting cover can appropriately diffuse light and transmit a certain amount or more of light through the lighting cover, it could not improve flexibility well.

Explanation of Reference Numerals

[0107] 10 Lighting device 11 Light source 12 Lighting cover 13 Bubble-containing layer 14 Surface layer 16 Reflective layer 17 Heat dissipation layer 20 LED sheet 21 LED 50, 70 Storage shelf 51 Desk 52, 72 Shelf board 52A Front end face 53, 73 Side plate

Claims

1. A lighting device comprising a light source and a lighting cover disposed so as to cover the light source and having a bubble-containing layer with bubbles inside. The bubble-containing layer is a foam obtained by foaming a foaming composition containing a polyolefin resin. The 25% compression strength of the foam is 10 to 900 kPa, and the total light transmittance of the lighting cover is 10% or more.

2. The lighting device according to claim 1, wherein the gel fraction of the foam is 10 to 70% by mass.

3. The lighting device according to claim 1 or 2, wherein the lighting cover further comprises a surface layer, and the bubble-containing layer and the surface layer are arranged in this order from the light source side.

4. The lighting device according to any one of claims 1 to 3, wherein the total light transmittance of the bubble-containing layer is 0.3% or more.

5. The lighting device according to any one of claims 1 to 4, wherein at least a part of the light source is disposed so as to be embedded inside the bubble-containing layer.

6. The lighting device according to any one of claims 1 to 5, wherein the light source comprises an LED.

7. The lighting device according to any one of claims 1 to 6, wherein the light source comprises a plurality of light-emitting elements and a base sheet, and the plurality of light-emitting elements are arranged on the base sheet.

8. The lighting device according to any one of claims 1 to 7, further comprising a reflective layer, wherein the reflective layer is provided on the side opposite to the side where the lighting cover of the light source is provided.

9. The lighting device according to any one of claims 1 to 8, which is disposed in a recess provided in a part of a ceiling, a wall surface, or a floor surface.

10. The lighting device according to any one of claims 1 to 8, which is suspended from a ceiling for arrangement.

11. A storage shelf comprising the lighting device according to any one of claims 1 to 8.

12. The storage shelf according to claim 11, wherein the lighting device is attached to at least one of a shelf board and a side board of the storage shelf.

13. The storage shelf according to claim 11 or 12, wherein a part of the shelf board of the storage shelf is pulled out to form a workbench of a desk.

14. The storage shelf according to claim 11 or 12, which is a storage shelf disposed on a desk.

15. The storage shelf according to claim 14, wherein the lighting device is attached to a shelf board disposed on the upper surface of the desk.

16. The storage shelf according to claim 14 or 15, comprising a shelf board disposed on the upper surface of the desk and a side board over which the shelf board is spanned, and the lighting device is attached to the side board.

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