JP7698500B2 - Lighting equipment and storage shelves - Google Patents

Description

The present invention relates to a lighting device and a storage shelf equipped with a lighting device.

Conventionally, lighting devices using light sources such as fluorescent lamps and incandescent lamps were common, but in recent years, LED lighting devices using LED light emitting elements have come into widespread use due to their long device life and low power consumption.
Illumination devices are often used as illumination light after light is diffused by a cover member having high light diffusion properties. For example, Patent Document 1 discloses that a cover provided to face an LED light-emitting element has diffusion properties and is made of a translucent resin such as polycarbonate resin or acrylic resin.

JP 2021-68715 A

However, the cover made of the translucent resin described in Patent Document 1 needs to be blended with light-diffusing particles to impart light diffusion properties. Furthermore, covers made of conventional translucent resins are generally made of hard materials, so a certain amount of space is required to install the cover, and there are significant space constraints.

Furthermore, in recent years, it has been considered to install lighting devices not only on the ceiling surface but also in various places in living spaces. However, lighting devices installed in places other than the ceiling surface may be bumped by users in daily life. However, covers made of conventional translucent resins are generally hard and cause relatively great pain to users when bumped, making it difficult to use them with a sense of security.

Therefore, the objective of the present invention is to provide a lighting device that has a certain degree of light diffusion without the need to incorporate additives for light diffusion, such as light-diffusing particles, into the lighting cover, and that can also impart a certain degree of flexibility to the lighting cover.

As a result of extensive investigations, the present inventors have found that the above problems can be solved by using a bubble-containing layer having bubbles therein for a lighting cover, and have completed the present invention as described below.
That is, the present invention relates to the following [1] to [16].
[1] A lighting device comprising: a light source; and a lighting cover arranged to cover the light source and having a bubble-containing layer having bubbles therein.
[2] The lighting device according to the above [1], wherein the bubble-containing layer is a foam.
[3] The lighting device according to the above [1] or [2], wherein the lighting cover further includes a surface layer, and the bubble-containing layer and the surface layer are disposed in this order from the light source side.
[4] The lighting device according to any one of the above [1] to [3], wherein the bubble-containing layer has a total light transmittance of 0.3% or more.
[5] The lighting device according to any one of the above [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 the above [1] to [5], wherein the light source comprises an LED.
[7] The lighting device according to any one of the above [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 the above [1] to [7], further comprising a reflective layer, the reflective layer being provided on a side of the light source opposite to a side on which the lighting cover is provided.
[9] The lighting device according to any one of the above [1] to [8], which is placed in a recess provided in a part of a ceiling, a wall, or a floor.
[10] The lighting device according to any one of the above [1] to [8], which is hung from a ceiling.
[11] A storage shelf equipped with the lighting device according to any one of [1] to [8] above.
[12] The storage shelf according to the above [11], wherein a lighting device is attached to at least one of the shelf boards and side boards of the storage shelf.
[13] The storage shelf according to [11] or [12] above, wherein a portion of the shelf can be pulled out to serve as a desk workbench.
[14] The storage shelf according to [11] or [12] above, which is placed on a desk.
[15] The storage shelf according to the above [14], wherein the lighting device is attached to a shelf placed on the top surface of the desk.
[16] A storage shelf as described in [14] or [15] above, comprising a shelf board placed on the top surface of the desk and a side board across which the shelf board is spanned, and the lighting device is attached to the side board.

The present invention provides a lighting device that has a certain degree of light diffusion without the need to incorporate additives for light diffusion, such as light-diffusing particles, into the lighting cover, and that can also impart a certain degree of flexibility to the lighting cover.

1 is a cross-sectional view of an embodiment of a lighting device of the present invention. FIG. 2 is a cross-sectional view of another embodiment of a lighting device of the present invention. FIG. 2 is a cross-sectional view of another embodiment of a lighting device of the present invention. FIG. 2 is a cross-sectional view of another embodiment of a lighting device of the present invention. FIG. 2 is an enlarged cross-sectional view showing the structure of a light source and a bubble-containing layer in the lighting device. 1 is a perspective view showing a first embodiment of a storage shelf of the present invention; FIG. 11 is a perspective view showing a second embodiment of the storage shelf of the present invention. FIG. 11 is a perspective view showing a third embodiment of the storage shelf of the present invention. FIG. 11 is a perspective view showing a modified example of the third embodiment of the storage shelf of the present invention. FIG. 13 is a perspective view showing another modified example of the third embodiment of the storage shelf of the present invention. FIG. 13 is a perspective view showing another modified example of the third embodiment of the storage shelf of the present invention. FIG. 13 is a perspective view showing another modified example of the third embodiment of the storage shelf of the present invention.

<Lighting equipment>
In the present invention, the lighting device includes a light source and a lighting cover that is disposed to cover the light source and has a bubble-containing layer having bubbles therein.

[light source]
The light source used in the present invention may be any light source used as a light source for lighting devices, such as a fluorescent lamp, an incandescent lamp, an LED, or an organic EL element, among which LEDs and organic EL elements are preferred, and LEDs are more preferred. LEDs are also called light-emitting diodes or inorganic LEDs.

As the LED, it is preferable to use a point light source composed of an LED chip or the like. The LED of the point light source has high light linearity, but by using a lighting cover having a bubble-containing layer, the light can be appropriately diffused as described below. In addition, the point light source has a small thickness, and it is possible to make the lighting device thin.
The shape of the LED as a point light source is not particularly limited, and may be a rectangle or any other shape. The size of the LED as a point light source is not particularly limited, and may be, for example, an area of about 5 ^cm2 or less, about 1 ^cm2 or less, or about 1 ^cm2 or less, or may be, for example, 0.001 ^cm2 or more, or 0.005 ^cm2 or more.

The light source may be an array of a plurality of light emitting elements, for example, an array of a plurality of LEDs. Specifically, the light emitting elements may be arranged in a line, or in any pattern such as a grid or staggered pattern.
The light source may be a light source sheet in which a plurality of light emitting elements are arranged on a sheet, and an LED sheet in which a plurality of LEDs are arranged on a base sheet is preferred. Each LED in the LED sheet is usually a point light source as described above. By using a light source sheet such as an LED sheet, a lighting device capable of irradiating a relatively wide area can be obtained with a simple configuration. In addition, when an organic EL element is used as the light source, a sheet-shaped organic EL element may be used as the light source sheet.

The base sheet used in the light source sheet is preferably a resin film, but may be a film other than a resin film. The base film may be transparent or may be a colored film. By using a colored film as the base sheet, the light from the light emitting element is reflected and easily emitted as illumination light to the front side where the illumination cover is provided.
The colored film is preferably colored in a color having a relatively high reflectance, such as white, a pale color, or a metallic color, and among these, a white film is preferable.

[Lighting cover]
The lighting cover is disposed so as to cover the light source and includes a bubble-containing layer. In the present invention, the lighting cover includes a bubble-containing layer, which allows the light from the light source to be diffused by the bubbles, thereby enabling uniform and even illumination.
In addition, light sources with high light linearity, such as LEDs, tend to have localized brightness and may cause eye damage when looking directly at the light source. However, in the present invention, even when a light source with high light linearity is used, the light from the light source can be diffused by using a lighting cover having an air bubble-containing layer, making it possible to provide uniform, even lighting.
Furthermore, as described below, 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 to emit soft light like indirect lighting, thereby creating a comfortable space.

The lighting cover may be composed of only the bubble-containing layer, but preferably includes a surface layer in addition to the bubble-containing layer. When the surface layer is provided, the bubble-containing layer and the surface layer are preferably arranged in this order from the light source side in the lighting cover.
The lighting cover (i.e., the bubble-containing layer or the laminate of the bubble-containing layer and the surface layer) may be appropriately molded into a desired shape by vacuum molding, compression molding, stamping molding, or the like.

<Bubble-containing layer>
The bubble-containing layer used in the lighting cover is preferably made of a foam. By using a foam for the bubble-containing layer, bubbles can be easily formed evenly inside. In addition, flexibility is easily ensured and the layer is easily deformed, so there are fewer space restrictions for installing the lighting cover. In addition, the layer is soft to the touch, which makes it easier for the user to feel at ease.
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 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, the bubble-containing layer can easily diffuse the light from the light source, and the light from the light source can easily be irradiated to the outside through the lighting cover.

(Total light transmittance)
The total light transmittance of the bubble-containing layer is, for example, 0.3% or more. By making the total light transmittance of the bubble-containing layer 0.3% or more, the lighting cover is made light-transmitting, and it becomes easy to emit light emitted from the light source to the outside at a certain amount or more. The total light transmittance of the bubble-containing layer is preferably 5% or more, more preferably 10% or more, even more preferably 20% or more, and even more preferably 30% or more. In addition, the total light transmittance of the bubble-containing layer is the higher the better from the viewpoint of light transmittance, but from the viewpoint of easily increasing light diffusion, it may be, for example, 95% or less, 90% or less, or 85% or less.

(Haze value)
The haze value of the bubble-containing layer is preferably 60% or more. By making the haze value of the bubble-containing layer 60% or more, the light from the light source can be easily diffused by the lighting cover. From the viewpoint of light diffusion, the haze value is preferably 70% or more, more preferably 80% or more, and even more preferably 90% or more. The upper limit of the haze value is not particularly limited, but from the viewpoint of light transmittance, it is sufficient if it is less than 100%.
The total light transmittance and the haze value can be set within the above ranges by appropriately adjusting the expansion ratio, the resin components, the compounds to be blended in the resin, etc. The total light transmittance can be measured using a haze meter in accordance with ASTM D1003. The haze value can be measured using a haze meter in accordance with ASTM D1003.

<Apparent density>
In the present invention, the apparent density of the bubble-containing layer is preferably 0.025 to 0.60 g/ ^cm3 . When the apparent density of the bubble-containing layer is within the above range, the light transmittance is improved while a certain degree of flexibility and mechanical strength is imparted. In addition, 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/ ^cm3 , even more preferably 0.10 to 0.40 g/ ^cm3 , and even more preferably 0.10 to 0.33 g/ ^cm3 .

<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 upper limit, the flexibility of the bubble-containing layer is improved, and the bubble-containing layer can be deformed into various shapes, reducing the space constraints for installing the lighting cover. In addition, it is easier to give the user a sense of security. On the other hand, when the 25% compressive strength is equal to or more than the lower limit, the mechanical strength of the bubble-containing layer is improved. From these viewpoints, the 25% compressive strength of the bubble-containing layer is more preferably 30 to 2000 kPa, more preferably 50 to 1500 kPa, and even more preferably 80 to 900 kPa.
The 25% compressive strength is a value measured by a method conforming to JIS K6767.

<Expansion ratio>
When the bubble-containing layer is a foam, the foam has an expansion ratio of preferably 1.3 to 40 times, more preferably 1.5 to 20 times, even more preferably 2 to 15 times, and even more preferably 3 to 10 times. When the expansion ratio is equal to or more than the lower limit, the foam is appropriately expanded, and the light transmittance is improved while the flexibility is also good. On the other hand, the light transmittance tends to be improved as the expansion ratio increases, but in order to ensure mechanical strength, it is preferable to set the expansion ratio to equal to or less than the upper limit. The expansion ratio can be calculated by dividing the density of the foam before expansion by the density (apparent density) of the foam after expansion.

The resin constituting the foam is not particularly limited, and various types of resins can be used. Specifically, urethane resin, acrylic resin, polyolefin resin, polystyrene resin, various elastomers, rubber components, etc. can be used, but among these, polyolefin resin is preferred. By using polyolefin resin, it is possible to impart appropriate flexibility and mechanical strength to the foam sheet. In addition, from the viewpoint of facilitating foaming, it is preferable that the resin is a thermoplastic resin.

The foam may be any foam obtained by foaming a foamable composition containing a resin, but it is preferable that the foam is obtained by foaming a foamable composition containing at least a polyolefin-based resin, and it is more preferable that the foam is obtained by crosslinking and foaming a foamable composition containing a polyolefin-based resin.
Examples of polyolefin resins include polyethylene resins, polypropylene resins, and ethylene-vinyl acetate copolymers. Among these, polyethylene resins are preferred from the viewpoint of flexibility.

<Degree of crosslinking (gel fraction)>
The foam of the present invention is preferably crosslinked as described above, and the degree of crosslinking (gel fraction) is preferably 10 to 70% by mass. When the gel fraction is equal to or more than the lower limit, sufficient crosslinking is formed in the foam, and the mechanical strength is likely to be high. When the degree of crosslinking is equal to or less than the upper limit, the flexibility of the foam is easily ensured. From this viewpoint, the degree of crosslinking is more preferably 15 to 60% by mass, and even more preferably 20 to 55% by mass.

The following provides a more detailed explanation of foams (polyolefin resin foams) that use polyolefin resin as the resin that constitutes the foam.

[Polyolefin resin foam]
The polyolefin resin foam of the present invention is a polyolefin resin foam obtained 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 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, the light transmittance generally tends to decrease, but in the present invention, by appropriately adjusting the expansion ratio, the resin components, the compounding materials to be mixed with the resin, etc., it is possible to obtain a polyolefin resin foam having excellent total light transmittance.

<Polyolefin resin>
The polyolefin resin is preferably at least one selected from the group consisting of polyethylene resin, polypropylene resin, and ethylene-vinyl acetate copolymer. These resins may be used alone or in combination of two or more.
The polyolefin resin foam of the present invention preferably contains a polyolefin resin as a main component, and specifically, the content of the polyolefin resin is preferably 65% by mass or more based on the total amount of resin components contained in the polyolefin resin composition. When the content of the polyolefin resin is 65% by mass or more, the mechanical strength, flexibility, etc. of the foam can be easily ensured. In addition, as described later, it is easy 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 resin components contained in the foam resin composition. In the following, the total amount of resin components contained in the polyolefin resin composition is simply referred to as "total amount of resin components".

<Polyethylene resin>
Examples of the polyethylene resin include low-density polyethylene resin (0.93 g/ ^cm3 or less, LDPE), medium-density polyethylene resin (more than 0.930 g/ ^cm3 and less than 0.942 g/ ^cm3 , MDPE), and high-density polyethylene resin (0.942 g/ ^cm3 or more, HDPE). A specific example of a suitable low-density polyethylene resin is linear low-density polyethylene resin (LLDPE).

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 becomes easier to reduce the rate of change in compressive strength of the foamed product.
The density of the linear low density polyethylene resin is preferably 0.90 g/ ^cm3 or more, more preferably 0.91 g/ ^cm3 or more and 0.93 g/ ^cm3 or less. The density of the high density polyethylene resin is preferably 0.98 g/cm3 or ^less , more preferably 0.95 g/ ^cm3 or more and 0.97 g/ ^cm3 or less. By setting the density of the high density polyethylene resin and the linear low density polyethylene resin within these ranges, it becomes easy to reduce the compressive strength, etc., without impairing the flexibility of the foam.

The polyethylene resin may be a homopolymer of ethylene, or may be a copolymer of ethylene and a small amount of α-olefin, in which ethylene is the main component (preferably 75% by mass or more, more preferably 90% by mass or more of the total monomers). The α-olefin preferably has 3 to 12 carbon atoms, more preferably 4 to 10 carbon atoms, and specific examples thereof include 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, and 1-octene. In the copolymer, these α-olefins may be used alone or in combination of two or more kinds.
The polyethylene resin may be used alone or in combination of two or more kinds.

<Polypropylene resin>
The polypropylene resin may be a homopolypropylene, which is a homopolymer of propylene, 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 the total monomers).
Examples of the copolymer of propylene with an α-olefin other than ethylene and propylene include block copolymers (block polypropylene), random copolymers (random polypropylene), and random block copolymers.
Examples of α-olefins 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, and 1-octene, and among these, ethylene is preferred 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 kinds.
The polypropylene resin may be used alone or in combination of two or more kinds.

In the present invention, any of polyethylene resin, polypropylene resin, or mixtures thereof polymerized with a polymerization catalyst such as a Ziegler-Natta compound, a metallocene compound, or a chromium oxide compound may be used. By using a polyethylene resin, particularly linear low-density polyethylene, obtained with a polymerization catalyst of a metallocene compound, it becomes easier to obtain a highly flexible foam.

Ethylene-vinyl acetate copolymer
The ethylene-vinyl acetate copolymer used as the polyolefin resin may be, for example, an ethylene-vinyl acetate copolymer containing 50% by mass or more of structural units derived from ethylene. Since the ethylene-vinyl acetate copolymer has high compatibility with polyethylene resins and polypropylene resins, the light transmittance of the foam is improved by using the ethylene-vinyl acetate copolymer in combination with one or more resins selected from the polyethylene resin and the polypropylene resin.
The density of the ethylene-vinyl acetate copolymer is preferably 0.92 g/cm ^or more, more preferably 0.93 g/cm or ^more , even more preferably 0.94 g/cm or ^more , and is preferably 0.97 g/cm ^or less, more preferably 0.96 g/cm ^or less. By setting the density of the ethylene-vinyl acetate copolymer within these ranges, it becomes easy to reduce the compressive strength, etc., without impairing the flexibility of the foam.

In the present invention, the polyolefin resin composition preferably uses any one of the above-mentioned polyolefin resins as a main component resin. Here, the main component resin means that any one of the polyolefin resins is contained in an amount of 65 mass% or more based on the total amount of the resin components, and therefore, it is preferable that the polyolefin resin composition contains any one of polypropylene resin, polyethylene resin, or ethylene-vinyl acetate copolymer in an amount of 65 mass% or more.
Generally, when two or more types of resins are blended, the resins do not mix completely, and cloudiness occurs due to mixing. However, in the present invention, by using one specific type of 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 improved.

The resin as the main component resin is preferably either a polypropylene resin or a polyethylene resin, and more preferably a polypropylene resin, among the above-mentioned resins. By using a polypropylene resin as the main component resin, the foam has excellent heat resistance and can be used for a long period of time even when heated by a light source.
More specifically, when a polypropylene resin is used as the main component resin, the polypropylene resin is contained in an amount of 65 mass% or more, preferably 75 mass% or more, more preferably 85 mass% or more, and most preferably 100 mass% based on the total amount of the resin components.
Also, preferably, one specific resin among polypropylene resins is contained in an amount of 65% by mass or more based on the total amount of resin components. For example, block polypropylene may be contained in an amount of 65% by mass or more, or random polypropylene may be contained in an amount of 65% by mass or more. In this case, the specific resin is contained in an amount of preferably 75% by mass or more, more preferably 85% by mass or more, and most preferably 100% by mass.

Similarly, when a polyethylene resin is used as the main component resin, the polyethylene resin should be contained in an amount of 65 mass% or more, preferably 75 mass% or more, and more preferably 85 mass% or more, based on the total amount of the resin components.
Also, preferably, one specific resin among polyethylene resins is contained in an amount of 65% by mass or more based on the total amount of resin components. For example, LDPE may be contained in an amount of 65% by mass or more, and in this case, the amount of the specific resin is preferably 75% by mass or more, more preferably 85% by mass or more.

In addition, when polypropylene resin is used as the main component resin, polypropylene resin may be used alone as a polyolefin resin, but in addition to polypropylene resin, at least one selected from polyethylene resin and ethylene-vinyl acetate copolymer may be used in combination. When polypropylene resin is used alone, it is not necessary to make it compatible with other polyolefin resins, so that the decrease in transparency caused by mixing of resins is prevented. In addition, by using polypropylene resin in combination with at least one selected from ethylene-vinyl acetate copolymer and polyethylene resin, compatibility is improved and transparency is maintained well. Furthermore, since it is easy to adjust the degree of crosslinking and the expansion ratio, it is easy to adjust the total light transmittance of the foam.
In this case, the content of polypropylene resin is preferably 65 to 95 mass% and at least one selected from polyethylene resin and ethylene-vinyl acetate copolymer is preferably 5 to 35 mass% based on the total amount of resin components, more preferably 75 to 95 mass% for the former and 5 to 25 mass% for the latter, and even more preferably 85 to 95 mass% for the former and 5 to 15 mass% for the latter.
The resin used in combination is preferably either a polyethylene resin or an ethylene-vinyl acetate copolymer, and more preferably an ethylene-vinyl acetate copolymer.
When the polypropylene resin is used as the main component resin, an elastomer may be further used as described below. In this case, the content of the elastomer is as described below.

On the other hand, even when polyethylene resin is used as the main component resin, at least one selected from polypropylene resin and ethylene-vinyl acetate copolymer may be used in combination with polyethylene resin as the polyolefin resin, but it is preferable to use polyethylene resin alone. However, when using polyethylene resin alone, it is preferable to further use an elastomer described below, and the content of the elastomer in this case is as described below.

The resin constituting the polyolefin resin foam may be composed of only polyolefin resin, or may be a mixture of polyolefin resin and elastomer. When the polyolefin resin composition contains an elastomer, the crystallinity of the polyolefin resin can be reduced, 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.
Furthermore, by using an elastomer, the flexibility and impact absorption properties of the foam can be improved.

As the elastomer, an elastomer having good compatibility with polyolefin resin is used, and specific examples thereof include ethylene-propylene-diene rubber (EPDM), ethylene-propylene rubber (EPM), and styrene rubber.
The elastomer also includes a thermoplastic elastomer, such as an olefin-based thermoplastic elastomer or a styrene-based thermoplastic elastomer.
The elastomer may be one of the above components alone or two or more of them may be used in combination. 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 preferred, and among them, styrene rubber and styrene-based thermoplastic elastomer are more preferred.

Styrene rubbers include various polymers such as random copolymers of styrene and conjugated diene compounds, and may be hydrogenated products thereof. Specific examples include styrene-butadiene copolymers (SBR) and hydrogenated products thereof (HSBR).

Examples of olefin-based thermoplastic elastomers include blend types and dynamic crosslinking types, and more specifically, examples of thermoplastic elastomers include those using thermoplastic crystalline polyolefins such as polypropylene and polyethylene as hard segments and fully vulcanized or partially vulcanized rubber as soft segments. Examples of soft segment components include butyl rubber, halobutyl rubber, EPDM, EPM, acrylonitrile/butadiene rubber, NBR, natural rubber, etc., and preferably EPDM is used.
Further, the olefin-based thermoplastic elastomer may be a block copolymer type. Examples of the block copolymer type include those having a crystalline block and a soft segment block, and more specifically, a crystalline olefin block-ethylene-butylene copolymer-crystalline olefin block copolymer (CEBC) is exemplified. In the 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.

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, such as isoprene and butadiene.
The styrene-based thermoplastic elastomer used in the present invention may be hydrogenated or may not be hydrogenated. When hydrogenated, the hydrogenation can be carried out by a known method.

The styrene-based 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), and styrene-ethylene/butylene-crystalline olefin block copolymer (SEBC).
The styrene-based thermoplastic elastomer is preferably a block copolymer, and more preferably SEBC. By using such an elastomer in combination with a polyolefin-based resin and further adjusting the expansion ratio, it is possible to improve the light transmittance of the foam.

Commercially available styrene-based thermoplastic elastomers include the product name "DYNARON 1320P" (styrene content 10% by mass) manufactured by JSR Corporation, the product name "DYNARON 8600P" (styrene content 15% by mass), and the product name "DYNARON 4600P" (styrene content 20% by mass).

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 mass %, and more preferably 8 to 22 mass %, based on the amount of the resin component. If the content of the elastomer is within these ranges, the optical transparency of the foam can be improved while maintaining the mechanical strength of the foam.

<Foaming Agent>
The polyolefin resin foam of the present invention can be obtained by foaming a polyolefin resin composition containing a resin including a polyolefin resin, a foaming agent, etc. As the foaming agent, a thermal decomposition type foaming agent is preferable.
As the thermal decomposition type blowing agent, organic blowing agents and inorganic blowing agents can be used. Examples of the organic blowing agent include azo compounds such as azodicarbonamide, azodicarboxylate metal salts (e.g., barium azodicarboxylate), azobisisobutyronitrile, etc., nitroso compounds such as N,N'-dinitrosopentamethylenetetramine, etc., hydrazine derivatives such as hydrazodicarbonamide, 4,4'-oxybis(benzenesulfonylhydrazide), toluenesulfonylhydrazide, etc., and semicarbazide compounds such as toluenesulfonylsemicarbazide, etc.
Examples of inorganic foaming agents include ammonium carbonate, sodium carbonate, ammonium hydrogen carbonate, sodium hydrogen carbonate, ammonium nitrite, sodium borohydride, and anhydrous monosodium citrate.
Among these, from the viewpoint of obtaining fine bubbles, and from the viewpoints of economy and safety, azo compounds are preferred, and azodicarbonamide is more preferred.
The thermally decomposable foaming agents may be used alone or in combination of two or more kinds.

The content of the foaming agent in the polyolefin 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, per 100 parts by mass of the polyolefin resin. By making the amount of foaming agent 1 part by mass or more, the resin composition is foamed appropriately, making it possible to impart appropriate flexibility and impact absorption properties to the foam. In addition, by making the amount of foaming agent 30 parts by mass or less, the foam is prevented from foaming more than necessary, and the mechanical strength, etc. of the foam can be improved.

<Additives>
The polyolefin resin composition may contain components such as a nucleating agent, a crosslinking aid, a decomposition temperature regulator, and an antioxidant.

<Nucleating Agent>
The nucleating agent used in the present invention is not particularly limited as long as it has the effect of improving the rate of progress 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 generated crystals can be reduced, thereby improving the transparency of the foam.
The nucleating agent used in the present invention is effective in increasing the rate of progress of the crystal nucleation process, and may be a substance that has the effect of promoting molecular chain orientation via the adsorption process of polymer molecular chains.
More specifically, examples of the compounds include high melting point polymers, organic carboxylic acids or metal salts thereof, aliphatic alcohols, dibenzylidene sorbitol or derivatives thereof, partial metal salts of rosin acid, amide compounds, inorganic fine particles, organic phosphoric acid compounds or metal salts thereof, imides, quinacridones, quinones, aromatic sulfonic acid salts or metal salts thereof, sugars, and mixtures thereof. These compounds may be used alone or in combination of two or more.

In the present invention, when a nucleating agent is used, 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, per 100 parts by mass of the polyolefin resin. When the content of the nucleating agent is equal to or more than the lower limit, the transparency of the foam is improved. On the other hand, when the content of the nucleating agent is equal to or less than the upper limit, the transparency of the foam can be improved while suppressing the production cost.
The polyolefin resin composition of the present invention may contain both a nucleating agent and an elastomer, but preferably contains either one of them. By containing either one of them, light transmittance can be effectively improved.

The crosslinking aid may be a polyfunctional monomer. By adding the crosslinking aid to the polyolefin resin, the amount of ionizing radiation irradiated in the step (2) described below is reduced, and the scission and deterioration of the resin molecules caused by the irradiation of ionizing radiation is prevented.
Specific examples of the crosslinking aid include compounds having three functional groups in one molecule, such as trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, trimellitic acid triallyl ester, 1,2,4-benzenetricarboxylic acid triallyl ester, 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; diallyl phthalate, diallyl terephthalate, diallyl isophthalate, ethylvinylbenzene, neopentyl glycol dimethacrylate, lauryl methacrylate, and stearyl methacrylate.
These crosslinking assistants may be used alone or in combination of two or more.

The amount of crosslinking aid added is preferably 0.5 to 10 parts by mass, more preferably 1.0 to 8 parts by mass, and even more preferably 1.5 to 5 parts by mass, per 100 parts by mass of polyolefin resin. By adding an amount of 0.5 parts by mass or more, it becomes possible to stably obtain the desired degree of crosslinking in the foam, and by adding an amount of 10 parts by mass or less, it becomes easier to control the degree of crosslinking in the foam.

The polyolefin resin composition may contain a decomposition temperature regulator. The decomposition temperature regulator is added to lower the decomposition temperature of the thermally decomposable foaming agent or to accelerate or adjust the decomposition rate. Specific examples of such compounds include zinc oxide, zinc stearate, and urea. The decomposition temperature regulator is added in an amount of, for example, 0.01 to 5 parts by mass per 100 parts by mass of the polyolefin resin in order to adjust the surface condition of the foam.

The polyolefin resin composition may contain an antioxidant. Examples of the antioxidant include phenol-based antioxidants such as 2,6-di-t-butyl-p-cresol and pentaerythritol tetrakis [3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], sulfur-based antioxidants such as dilauryl thiodipropionate, phosphorus-based antioxidants, and amine-based antioxidants. The antioxidant is blended in an amount of, for example, 0.01 to 5 parts by mass per 100 parts by mass of the polyolefin resin.
In addition to the above, the polyolefin resin composition may contain additives that are generally used in foams, such as a heat stabilizer, a colorant, a flame retardant, an antistatic agent, and a filler.

[Method of manufacturing foam]
The method for producing the polyolefin resin foam is not particularly limited, but the polyolefin resin foam can be produced by heating a foamable sheet made of a polyolefin resin composition containing at least a resin and a thermally decomposable foaming agent to foam the thermally decomposable foaming agent. More specifically, the production method preferably includes the following steps (1) to (3).
Step (1): A step of forming a foamable sheet made of a polyolefin resin composition containing at least a resin and a thermally decomposable 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 foam the thermally decomposable foaming agent and obtain a foam.

In the step (1), the method for forming the foamable sheet is not particularly limited, but may be, for example, by feeding the resin and additives to an extruder, melt-kneading the mixture, and extruding the polyolefin resin composition from the extruder into a sheet. The foam may be formed by pressing the polyolefin resin composition.
The molding temperature of the foamable sheet (that is, the temperature during extrusion or pressing) is preferably 50°C or higher and 250°C or lower, and more preferably 80°C or higher and 180°C or lower.

In step (2), the method for crosslinking the polyolefin resin composition is to irradiate the foamable sheet with ionizing radiation such as electron beams, α-rays, β-rays, or γ-rays. The dose of the ionizing radiation may be adjusted so that the crosslinking degree of the resulting foam falls within the desired range described above, but is preferably 1 to 12 Mrad, and more preferably 1.5 to 8 Mrad.

In step (3), the heating temperature when the polyolefin resin composition is heated to expand the thermally decomposable foaming agent 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.

In the present manufacturing method, the foam may be stretched in either MD or TD or both. The stretching of the foam may be performed after the foam sheet is foamed to obtain a foam, or may be performed while the foam sheet is being foamed. In addition, when the foam is stretched after the foam sheet is foamed to obtain a foam, the foam may be stretched while maintaining the molten state at the time of foaming without cooling the foam, or the foam may be stretched after cooling the foam by heating it again to a molten or softened state. Stretching the foam makes it easier to make it thinner. In addition, the foam may be heated to, for example, 100 to 280°C, preferably 150 to 260°C, during stretching. In the present invention, by stretching the foam, the bubble diameter of the foam becomes larger along either MD or TD or both, and light transmittance tends to be increased.

However, the present production method is not limited to the above, and a foam may be obtained by a method other than the above. For example, instead of irradiating ionizing radiation, crosslinking may be performed by a method in which an organic peroxide is blended in advance with the polyolefin resin composition, and the foamable sheet is heated to decompose the organic peroxide.
In the production of the foam of the present invention, the obtained foam may be sliced to obtain a foam having a desired thickness.

[Surface layer]
As described above, it is preferable that a surface layer is provided 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 of the lighting cover can be improved. The surface layer is sometimes called a surface decorative sheet or the like.
Specific examples of the surface layer used for the lighting cover include resin sheets exemplified by polyvinyl chloride sheets, mixed resins of polyvinyl chloride and ABS resin, and thermoplastic elastomer sheets, as well as woven fabrics, knitted fabrics, and nonwoven fabrics using natural fibers or artificial fibers, and leathers such as artificial leathers and synthetic leathers. Of these, resin sheets are preferred as the surface layer.

The surface layer may be provided with a suitable geometric pattern of projections and recesses, or the surface may be printed, etc. Furthermore, from the viewpoint of preventing scratches, the surface of the surface layer may be provided with various coatings.
The unevenness may be a grain pattern formed on the surface of the surface layer from the viewpoint of enhancing the design. Alternatively, a leather or wood grain pattern may be applied to the surface of the surface layer using a silicone stamper or the like having unevenness transferred from genuine leather, stone, wood, etc. The printing applied to the surface of the surface layer is not particularly limited, and may be a wood grain or leather print.

It is preferable to use a surface layer that is light-transmitting. When the surface layer has light-transmitting properties, the light emitted from the light source can be appropriately irradiated to the outside through the bubble-containing layer and the surface layer. In order to increase the efficiency of light emission from the light source, 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 even more preferably 10% or more. In order to make the bubble-containing layer such as a foam less visible 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 even more preferably 40% or less.

The thickness of the surface layer is not particularly limited, but is, for example, 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, it is possible to ensure high light transmittance while improving the mechanical strength of the surface layer. In addition, by increasing the thickness of the surface layer, it is possible to prevent the inside of a foam or the like from being seen through.

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 extrusion lamination, adhesive lamination in which an adhesive is applied and then bonded, thermal lamination (heat fusion), hot melt, and high-frequency welder methods. The surface layer may be bonded to the bubble-containing layer with an adhesive or adhesive tape, but the two may be bonded together by any method.

The lighting cover of the present invention may have a layer other than the above-mentioned surface layer, such as a printed layer, and the bubble-containing layer. For example, a printed layer may be provided 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), thereby improving the design of the lighting cover. In addition, the printed layer may provide a light-shielding area through which illumination light does not pass. A known method such as an inkjet method may be used as a method for forming the printed layer.

In the present invention, even when a surface layer is provided as described above, it is sufficient to have a certain level of total light transmittance, and therefore the transmittance of the lighting cover is sufficient as long as it is at least a certain level. The total light transmittance of the lighting cover may be, for example, 0.3% or more in order to increase the efficiency of light emission from the light source, but is preferably 1% or more, more preferably 5% or more, and even more preferably 10% or more. 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.
As described above, the lighting cover has a region where the total light transmittance is partially decreased due to the provision of a printed layer on the surface layer or the bubble-containing layer, and in such a case, the total light transmittance of the region where the total light transmittance of the lighting cover is maximum is meant. The total light transmittance of the lighting cover can be adjusted by the thickness, composition, etc. of the surface layer or the bubble-containing layer.

The specific configuration of the lighting device of the present invention will be described in more detail with reference to Figures 1 to 4. In the following description, a case where a light source sheet is used as the light source 11 is illustrated, but the light source is not limited to the light source sheet. Also, in Figures 1 to 4, an example is shown in which the lighting cover includes a surface layer and a bubble-containing layer, but the surface layer may be omitted as appropriate.
1, the lighting device 10 includes, for example, a light source 11 and a lighting cover 12, and may be arranged such that, for example, the lighting cover 12 is laminated on the surface of the light source 11. 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.

(reflective layer)
The lighting device may also have a reflective layer. As shown in Fig. 2, the reflective layer 16 may be provided on the rear side of the light source 11, i.e., the side opposite to the side where the lighting cover 12 is provided. When the reflective layer 16 is provided, stray light emitted from the light source to the rear side is reflected by the reflective layer 16 and emitted to the front side, improving the emission efficiency of light from the light source in the lighting device.
The reflective layer is not particularly limited, but may be, for example, a colored film or a colored plate. The colored film is preferably colored in a color with a relatively high reflectance, such as white, a light color, or a metallic color, and among these, a white film is preferred. The colored plate is preferably colored in a color with a relatively high reflectance, such as white, a light color, or a metallic color, and among these, a white plate is preferred.
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, calcium carbonate, etc. Also, as the colored plate, a resin plate containing a colorant may be used.
The reflective layer 16 is effective when light from the light source 11 is emitted to the rear side. For example, when the light source 11 is a light source sheet, it is effective to use the reflective layer 16 when the base sheet constituting the light source sheet has light transparency.

The reflective layer described above may be attached to the light source, although there is no particular limitation to this. The reflective layer may be attached to the light source using, for example, an adhesive or an adhesive tape. If the reflective layer is a resin film, it may be attached to the light source by, for example, an extrusion lamination method, an adhesive lamination method in which an adhesive is applied and then attached, a thermal lamination method (thermal fusion method), a hot melt method, a high-frequency welder method, or the like, but it may be attached to the light source by any method.

The reflective layer 16 may also be a coating formed on the back surface of a light source (e.g., a light source sheet), or a coating formed on the front surface of a heat dissipation layer composed of a metal plate, graphite sheet, or the like, which will be described later. The coating may be, for example, a colored layer, and may be a layer formed by applying an ink containing a colorant. Specific examples of colorants are as described above.

(heat dissipation layer)
The lighting device may also have a heat dissipation layer. As shown in Fig. 3, the heat dissipation layer 17 may be provided on the back side of the light source 11, i.e., on the side opposite to the side on which the lighting cover 12 is provided. The heat dissipation layer 17 is a layer formed of a material with high thermal conductivity, and may be a metal layer formed of a metal plate such as an aluminum plate or a stainless steel plate, or may be a layer other than a metal layer such as a graphite sheet. When the heat dissipation layer is formed of a metal layer, it also functions as a reflective layer.
When the lighting device 10 is provided with a heat dissipation layer 17, the heat dissipation layer 17 may be provided together with the reflective layer 16. In this case, it is preferable that the reflective layer 16 and the heat dissipation layer 17 are provided in this order from the light source 11 side as shown in FIG.
The heat dissipation layer 17 is not particularly limited, but may be attached 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.

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 side of the base sheet 21. In addition, a bubble-containing layer 13 is typically laminated on the LED sheet 20, and 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 disposed so as to be embedded inside the bubble-containing layer 13. In this way, in the present invention, by disposing a part of the light source so as to be embedded inside the bubble-containing layer 13, it is possible to make the lighting device thinner.
In the above explanation, an example has been described in which an LED sheet is used as a light source, but even in cases other than an LED sheet, at least a portion of a light source such as a light-emitting element may be embedded, and in the present invention, it is not necessarily required that at least a portion of the light source be embedded inside the bubble-containing layer 13.

<How to use>
The lighting device of the present invention can be used for various purposes, for example, it is installed on a ceiling and used to illuminate a room or the like. The lighting device installed on the ceiling may be a so-called embedded type. The embedded type lighting device is a lighting device installed in a recessed portion provided in a part of the ceiling. The lighting device of the present invention can be made thin by using a light source sheet such as an LED sheet, so that in the embedded type, the lighting device can be installed inside a relatively shallow recessed portion. The embedded type lighting device can be made into a lighting device with a high design quality by arranging the surface (for example, the surface layer) of the lighting cover on the same plane as the ceiling surface.

Furthermore, the lighting device installed on the ceiling is not limited to the embedded type, but may be a hanging type. A hanging type lighting device is used by suspending the lighting device from the ceiling surface using a jig or the like. However, the lighting device installed on the ceiling surface is not limited to the embedded type or the hanging type, but may be of any type, and for example, the lighting device may be attached to the ceiling surface other than the recessed portion without being suspended.
The lighting device of the present invention may be installed on a place other than a ceiling, for example, on a wall surface, a floor surface, etc. The lighting device installed on a wall surface, a floor surface, etc. may be an embedded type arranged in a recess provided in a part of the wall surface or the floor surface, or may be a type other than the embedded type.

The lighting device of the present invention may be used in a manner other than that of being attached to a ceiling, wall, floor, etc., and may be attached to a portion of a building, particularly a residential building, other than a ceiling, wall, or floor. The lighting device may also be used in a manner of being attached to furniture, etc.
The lighting device may be attached to furniture, a ceiling surface, a wall surface, a floor surface, or other parts by any fixing means, including, but not limited to, adhesive tape, adhesive, screws, or the like.

Among them, it is preferable that the lighting device is attached to a storage shelf for use. The storage shelf may be any type of storage shelf, but typically has shelves arranged in a horizontal direction. The storage shelf also typically has side panels arranged in a vertical direction, and the shelves may be bridged between the side panels. The uppermost shelf panel may be called a top panel, and the lowermost shelf panel may be called a bottom panel. Generally, items such as clothes, books, household goods, and food are stored on the storage shelf.
The storage shelf may be any type of storage shelf, such as a bookshelf, a clothing shelf, a food shelf, etc. Also, the storage shelf may be a shelf provided on a desk or the like.

6 shows a first embodiment of the 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 arranged on the upper surface (desk surface) of a desk 51, and the shelf board 52 is bridged between two side panels 53, 53 installed on the upper surface of the desk 51. In this embodiment, the lighting device 10 is attached to a front end surface 52A of the shelf board 52. The lighting device 10 can be made thin and does not protrude significantly beyond the front end surface 52A, so that it does not give a feeling of oppression to the user and has excellent design.
Here, the shelf board 52 to which the lighting device 10 is attached is a shelf board located in a position close to the top surface of the desk 51, and the lighting device 10 attached to the front end surface 52A of the shelf board 52 can illuminate the top surface of the desk 51, and can be effectively used as a hand lamp. Furthermore, the lighting device 10 has a flexible bubble-containing layer, which makes it soft to the touch and gives the user a sense of security.

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 shelves 62, 62, and further includes side panels 63, 63 across which the shelves 62 are spanned. The side panels 63, 63 are attached to the top surface of the desk 51. The storage shelf 60 also includes a back panel 64 on the back side, but the back panel 64 may be omitted as appropriate.
7, the lighting device 10 is disposed on a front end surface 62A of the shelf board 62 that is disposed closest to the desk among the plurality of shelf boards 62. The lighting device 10 is also provided on a front end surface 63A of the side board 63. Note that, in this embodiment, the lighting device 10 provided on the front end surface of the side board 63 is disposed on a lower portion of the side board 63. The lower portion of the side board 63 is, for example, a portion that is lower than the shelf board 62 that is disposed closest to the desk, and is a portion that connects the shelf board 62 and the upper surface of the desk 51.

In this embodiment, the lighting device 10 can also be made thin and, even when attached to the front end faces 62A, 63A, does not protrude significantly beyond the front end faces 62A, 63A, resulting in an excellent design. Furthermore, by arranging the lighting device on the lower portion of the front end face 62A of the shelf board 62 and the front end face 63A of the side board 63, which are located close to the top surface of the desk 51, the top surface of the desk 51 can be properly illuminated. Furthermore, the lighting device 10 is provided with a flexible bubble-containing layer, which makes it soft to the touch and provides a sense of security to the user.

The storage shelf in which the lighting device is provided on the front end surface of at least one of the side panels and the shelf board as described above is not limited to a storage shelf provided on a desk, but may be any storage shelf.
In the second embodiment described above, the position where the lighting device 10 is arranged is one example, and is not limited to the above-mentioned arrangement position, and for example, the lighting device may be arranged on the inner surface of the shelf board 62 or the inner surface of the side board 63, or may be arranged in front of the back board 64. In such a case, the shelf board 62, side board 63, and back board 64 on which the lighting device is arranged are not particularly limited, but in order to properly illuminate the upper surface of the desk 51, it is preferable that the shelf board 62 arranged closest to the desk (desk surface) among the multiple shelf boards 62, or the side board 63 or back board 64 in a portion lower than the shelf board 62 arranged closest to the desk.

8 shows another form of the storage shelf (third embodiment). The storage shelf 70 in this embodiment is box-shaped, with both side panels 73, 73, a top panel 75, and a bottom panel 76 constituting the sides, top surface, and ground of the storage shelf 70. The storage shelf 70 is also provided with a back panel 74 that constitutes the back surface. A shelf panel 72 is also provided, and the shelf panel 72 is bridged between the both side panels 73, 73.
The storage shelf 70 is not particularly limited, but may be a fixed type or a movable type equipped with casters. The storage shelf 70 is generally provided with an openable door (not shown) on the front side.

8, the lighting devices 10 are provided on the inner surfaces of both side panels 73, a top panel 75, and a bottom panel 76 (i.e., both side surfaces, the top surface, and the ground surface) of the storage shelf 70. The storage shelf 70 is box-shaped and the inside tends to be dark, but by providing the lighting devices 10 on the inner surfaces, the inside of the storage shelf 70 can be properly illuminated.
In addition, the lighting device 10 is small in size and does not protrude too far from the inner surface of the storage shelf. Therefore, even if the lighting device 10 is installed on the inner surface of the storage shelf 70, it does not feel oppressive and does not make the storage space smaller than necessary, and it has excellent design. Furthermore, it is soft to the touch and gives the user a sense of security.

In addition, in this embodiment, the lighting device 10 is arranged on the front side of the inner surface (i.e., both side surfaces, the top surface, and the ground). By being arranged on the front side in this way, it becomes easier to properly illuminate areas that are easily visible to the user with less power consumption. Furthermore, the lighting device 10 arranged on the front side is preferably arranged so as to extend along the circumferential direction inside the storage shelf 70, so that the interior of the storage shelf 70 can be illuminated from both sides and from above and below.

However, the position where the lighting device 10 is arranged is not particularly limited, and the lighting device 10 may be arranged on substantially the entire surface of each of both side surfaces, the top surface, and the ground. Also, as shown in Fig. 9, the lighting device 10 may be arranged so as to extend toward the back (i.e., in the front-to-rear direction). In this case, for example, the lighting device 10 may be arranged at the four corners of the storage shelf 70 (i.e., at or near the connection portion between the side panel and the top surface, and at or near the connection portion between the side panel and the top surface).
As shown in FIG. 10, the storage shelf may be provided with a partition plate 77 extending in the vertical direction.

Furthermore, the storage shelf may be provided with lighting devices on parts other than the side, top, and ground, and for example, as shown in Fig. 11, lighting devices may be attached to the main surface of a partition board 77 or to the main surface of a shelf board 72 other than the top and ground. By attaching lighting devices 10 to the partition board 77 and shelf board 72 as well, each space partitioned by the shelf board 72 and partition 77 can be appropriately illuminated by lighting devices 10 as shown in Fig. 11.
When the lighting devices 10 are attached to the partition boards 77 or the shelf boards 72, the positions at which the lighting devices 10 are attached are not particularly limited, but as shown in Fig. 11, in the relatively large spaces S1 and S2, the lighting devices 10 may be attached to the four corners. Also, in the relatively small spaces S3 to S6, instead of being attached to the four corners, the lighting devices 10 may be provided on both sides of each space so as to sandwich the space therebetween, so as to illuminate the space from both sides. Of course, although not shown, the lighting devices 10 may be provided above and below the space so as to illuminate the space from above and below, or other configurations may be used.
12, the light source 10 may be disposed so as to extend along the circumferential direction of each space so as to surround the entire periphery of each space, which makes it easier for each space to be appropriately illuminated by the lighting devices disposed 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 panel 74 or the like in addition to the above.

The storage shelves shown in Figures 8 to 12 may be of a type in which at least a portion of the shelf boards, including the top board and bottom board, can be pulled out further forward than the other shelf boards to become a work table (desk surface) of a desk. The shelf boards may be slid forward to become the desk surface, or folded up and pulled out to become the desk surface, or a board leaned against the back panel may be set to become the desk surface. In this case, the lighting device provided on the storage shelf may illuminate the desk surface. In this case, the position of the lighting device that illuminates the desk surface may be the same as the position when the storage shelf is provided on a desk, as described in the second embodiment.

8 to 12 show an example of a box-shaped storage shelf, but the present invention is not limited to the box-shaped storage shelf. For example, buildings, particularly residential buildings, have a storage section called a closet, and a lighting device may be provided on the inner surface of the storage section.
For example, the inner surface of the storage section generally has two side surfaces, a top surface, a base surface, and a back surface, similar to the storage shelves shown in Figures 8 to 12, and a lighting device may be provided on the inner surfaces of any or all of these surfaces.
Also, in the storage section, any of the aspects shown in Fig. 8 to 12 may be adopted. Thus, in the storage section, 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 so as to extend toward the back as shown in Fig. 9, or may be arranged in other ways.
Furthermore, the storage section does not necessarily have to be a storage shelf, and may be one that does not have a shelf board, a partition board, etc. Furthermore, when the storage section is provided with a storage shelf or a partition board, a lighting device may be provided on the shelf board or the partition board as shown in Figs.

In a box-shaped storage shelf or storage section, the lighting device may be in any form as long as it is attached to at least one of the inner surfaces of both side surfaces, the top surface, the ground surface, and the back surface, and the main surfaces of the partition boards and shelves.
In addition, in a storage shelf, the lighting device may be attached to the front end surface of a side panel or shelf as shown in the first and second embodiments, and may also be attached to at least one of the inner surfaces of both side surfaces, the top surface, the ground surface, and the back surface, and the main surfaces of the partition panels and shelf panels as shown in the third embodiment.

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

[Measurement method]
The methods for measuring the various physical properties 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 expandable sheet before expansion by the density (apparent density) of the foam after expansion.

<Degree of crosslinking (gel fraction)>
A test piece of about 100 mg was taken from the foam sheet, and the weight A (mg) of the test piece was precisely weighed. Next, the test piece was immersed in 30 ^cm3 of xylene at 120°C and left for 24 hours, and then filtered through a 200-mesh wire net to collect the insoluble matter on the wire net, which was then vacuum-dried, and the weight B (mg) of the insoluble matter was precisely weighed. From the obtained value, the degree of crosslinking (mass%) was calculated using the following formula.
Degree of crosslinking (mass%) = (B/A) x 100

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

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

<Illumination light evaluation>
An LED light source, which is a point light source, was placed above the irradiated table, and light from the LED light source was irradiated onto the irradiated table through a lighting cover placed so as to be in contact with the lower side of the LED light source, and the maximum diameter S2 of the area irradiated with light on the irradiated table was measured. In addition, the lighting cover was removed and the maximum diameter S1 of the area irradiated with light on the irradiated table was similarly measured. When the following formula was satisfied, the light diffusion of the lighting cover was evaluated as "A" as being good, and when it was not satisfied, 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°

<Flexibility assessment>
The flexibility of the lighting covers of each of the Examples and Comparative Examples was evaluated by touch according to the following evaluation criteria.
A: It is highly flexible and easily deformable, and has a soft feel that gives the user a sense of security.
B: The flexibility is low and the material cannot be deformed, and the texture is hard and the user cannot feel comfortable.

<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: Tosoh Corporation "Nipolon-Z ZF231B" (density: 0.917 g/cm ³ )
EVA (1): Tosoh Corporation "Ultrathene 636" (density: 0.941 g/cm ³ )
EVA (2): Tosoh Corporation "Ultrathene 710" (density: 0.949 g/cm ³ )

[Elastomer]
HSBR: JSR Corporation "DYNARON 1320P"

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

Example 1
80 parts by weight of polypropylene resin (PP), 19 parts by weight of polyethylene resin (LLDPE), 2 parts by weight of nucleating agent, 8 parts by weight of foaming agent, 3 parts by weight of crosslinking assistant agent, and 0.8 parts by weight of antioxidant were melt-kneaded and pressed to obtain a foamable sheet having a thickness of 0.3 mm. Both sides of the obtained foamable sheet were irradiated with an electron beam of 3 Mrad at an acceleration voltage of 500 keV to crosslink the foamable sheet. Next, the crosslinked foamable sheet was heated to 250°C to foam, and a foam with an apparent density of 0.09 g/cm ³ and a thickness of 1.0 mm was obtained. The obtained foam was used as a lighting cover and various evaluations were performed. The evaluation results are shown in Table 1.

Examples 2 to 5
The same procedure as in Example 1 was carried out, except that the formulation of the polyolefin resin composition was changed as shown in Table 1, and the amount of electron beam irradiation was adjusted to obtain the degree of crosslinking shown in Table 1. The obtained foam was used as a lighting cover and various evaluations were carried out. The evaluation results are shown in Table 1.

<Comparative Example 1>
Various evaluations were carried out using a commercially available diffusion plate (product name "Sumipex", manufactured by Sumitomo Chemical Co., Ltd.) as a lighting cover instead of the foam.

In each embodiment of the present invention, by using a foam that is a bubble-containing layer as the lighting cover, it is possible to properly diffuse light in the lighting cover while maintaining good flexibility, and to transmit a certain amount of light or more through the lighting cover. On the other hand, a diffusion plate used as a conventional lighting cover can properly diffuse light while allowing a certain amount of light or more to transmit through the lighting cover, but does not provide good flexibility.

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 surface 53, 73 Side board

Claims (16)

A lighting cover is provided, the lighting cover being disposed so as to cover the light source and having an air bubble-containing layer having air bubbles therein ;
the bubble-containing layer is a foam obtained by foaming a foamable composition containing a polyolefin-based resin, the foam has a 25% compressive strength of 10 to 900 kPa, and the lighting cover has a total light transmittance of 10% or more . 2. The lighting device according to claim 1, wherein the foam has a gel fraction of 10 to 70 mass % . 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. 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. The lighting device according to any one of claims 1 to 4, wherein at least a portion of the light source is disposed so as to be embedded inside the bubble-containing layer. The lighting device according to any one of claims 1 to 5, wherein the light source comprises an LED. 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. The lighting device according to any one of claims 1 to 7, further comprising a reflective layer, the reflective layer being provided on the side of the light source opposite the side on which the lighting cover is provided. The lighting device according to any one of claims 1 to 8, which is placed in a recess provided in a part of a ceiling, a wall, or a floor. The lighting device according to any one of claims 1 to 8, which is suspended from a ceiling. A storage shelf equipped with a lighting device according to any one of claims 1 to 8. The storage shelf according to claim 11, in which a lighting device is attached to at least one of the shelf boards and side boards of the storage shelf. The storage shelf according to claim 11 or 12, in which a part of the shelf of the storage shelf can be pulled out to serve as a desk workbench. The storage shelf according to claim 11 or 12, which is a storage shelf placed on a desk. The storage shelf according to claim 14, in which the lighting device is attached to a shelf placed on the top surface of the desk. 16. The storage shelf according to claim 14, further comprising a shelf board arranged on an upper surface of the desk and a side board across which the shelf board is spanned, the lighting device being attached to the side board.