JP7777916B2 - light reflector - Google Patents

Description

The present invention relates to a light reflector with excellent light reflectivity.

Conventionally, there are light reflectors made of crystalline polyester resin foam (Patent Document 1).

However, there is a demand for even higher light reflectivity.

JP 2015-197449 A

The present invention has been made in consideration of the above points, and aims to provide a light reflector with excellent light reflectivity.

The first aspect relates to a light reflector comprising a resin foam of a polymer composition containing a polyolefin and a rubber component and/or a polystyrene-based thermoplastic elastomer.

A second aspect is the first aspect , characterized in that the resin foam is compressed and fixed.

A third aspect is the first aspect , characterized in that a plurality of the resin foams are laminated and compressed and fixed.

A fourth aspect is any one of the first to third aspects , characterized in that a light-reflecting resin film is laminated on the resin foam.

A fifth aspect is the fourth aspect , characterized in that the light-reflecting resin film has titanium oxide dispersed in the resin film or a metal layer vapor-deposited thereon.

A sixth aspect is characterized in that, in any one of the first to fifth aspects , the resin foam has a bubble diameter of 5 to 250 μm, and the bubble diameter increases from the surface toward the inside.

A seventh aspect is any one of the first to sixth aspects , characterized in that the resin foam is a supercritical foam.

The present invention provides a light reflector with excellent light reflectivity. Furthermore, by laminating a light-reflecting resin film onto a resin foam, the light reflectivity of the light reflector can be further improved.

FIG. 2 is a cross-sectional view of the light reflecting plate according to the first embodiment. FIG. 10 is a cross-sectional view of a light reflecting plate according to a second embodiment. FIG. 2 is a schematic diagram showing the state of bubbles in a resin foam. 1 is a table showing the configurations and light reflectances of Examples 1 to 7 and Comparative Examples 1 and 2. 1 is a table showing the formulations of Examples 1 to 12. 1 is a table showing the configurations and light reflectances of Examples 1, 3, 5, and 7, Comparative Examples 1 and 2, and Examples 13 to 17.

The light reflecting plate 10 of the first embodiment shown in Figure 1 is composed of a resin foam 11 made of a polymer composition containing (A1) polyolefin and (A2) a rubber component and/or a polystyrene-based thermoplastic elastomer. The resin foam 11 has a cellular structure and is formed by supercritical foam molding.

Supercritical foam molding is a well-known foam molding method in which a gas (nitrogen or carbon dioxide) in a supercritical state, where the temperature and pressure exceed the critical state, is dissolved in a molten resin, and then the pressure is suddenly reduced to generate fine bubbles.
The resin foam 11 constituting the light reflector 10 is in the form of a sheet having a cellular structure formed by extrusion molding using a supercritical foam molding method.

Resin foam 11 extrusion-molded using supercritical foam molding preferably has air bubbles with a diameter (air bubble diameter) of 5 to 250 μm. As shown in FIG. 3, the diameter of the air bubbles 13 increases from the surface of resin foam 11 toward the interior. This increase in the air bubble diameter from the surface toward the interior of resin foam 11 increases the diffuse reflection of light that enters resin foam 11, resulting in high light reflectivity. The air bubble diameter is determined by taking a microscope image of a cross section of resin foam 11 cut along its thickness direction, measuring the diameters of 30 air bubbles in the resulting image, and averaging the measured values. Resin foam 11 also has thin skin layers 15 on both sides. The skin layers 15 have a dense surface structure formed during supercritical foam molding, which enhances light reflectivity.

(A1) Examples of polyolefins (excluding ethylene-propylene rubber) include polyethylene, polypropylene, polybutene-1, ethylene-propylene copolymers, ethylene-α-olefin copolymers, and polymer blends of these.

Polyethylene may be high-density polyethylene, medium-density polyethylene, linear low-density polyethylene, low-density polyethylene, etc. Polypropylene may be atactic, isotactic, syndiotactic, random, etc. Polypropylene with high elongational viscosity, such as polypropylene with long-chain branches in the main chain (HMS-PP), which is considered suitable for foaming, or polypropylene with a wide molecular weight distribution containing high molecular weight components, may also be used. Copolymers may be random or block copolymers, and may be thermoplastic resins or thermoplastic elastomers. Ethylene-propylene copolymers include ethylene-propylene copolymers (EPR), which cure to become rubber-like elastomers. However, since this is included in the rubber component, it is excluded from the polyolefins of the present invention. Resinous ethylene-propylene copolymers are included in the polyolefins of the present invention. Other thermoplastic polymers may also be present as long as they do not impair the properties of the resin foam of the present invention.

Examples of the rubber component (A2) include ethylene and propylene copolymers such as EPR (EPM), styrene-ethylene-butadiene-styrene rubber (SEBS), styrene-butadiene rubber (SBR), styrene-butadiene-styrene rubber (SBS), styrene-ethylene-propylene rubber (SEP), isoprene-butadiene rubber, styrene-isoprene-butadiene rubber, styrene-isoprene rubber, and ethylene-propylene-diene copolymer rubber (EPDM).

Since it is difficult to form a foam using a method of reducing pressure from a supercritical state when the rubber component has a low molecular weight, a high molecular weight component with a weight-average molecular weight of 200,000 or more is preferred. In particular, ethylene-propylene-diene copolymer rubber (EPDM) and styrene-ethylene-butadiene-styrene rubber (SEBS) with a weight-average molecular weight of 200,000 or more are preferred rubber components, and it is preferable to use ethylene-propylene-diene copolymer rubber (EPDM) together with polypropylene and polyethylene.

The polystyrene-based thermoplastic elastomer (A2) may be a block copolymer in which polystyrene is bonded to one or both ends of a polymer consisting of a hydrocarbon chain. Examples include block copolymers of styrene and butadiene, isoprene, isobutylene, etc., or further hydrogenated versions of these block copolymers. Examples include styrene-butadiene-styrene block copolymer (SBS), styrene-ethylene-butylene-styrene block copolymer (SEBS) obtained by hydrogenating SBS, styrene-isoprene-styrene block copolymer (SIS), styrene-ethylene-propylene-styrene block copolymer (SEPS) obtained by hydrogenating SIS, styrene-isoprene-butadiene-isoprene-styrene block copolymer, and styrene-ethylene-propylene-styrene block copolymer (SEEPS) obtained by hydrogenating the styrene-vinylisoprene-styrene block copolymer, and hydrogenated versions thereof, styrene-isobutylene-styrene block copolymer, styrene-butadiene block copolymer, and hydrogenated versions thereof, styrene-isobutylene-styrene block copolymer, and hydrogenated versions thereof, styrene-isobutylene-block copolymer, and hydrogenated versions thereof, and styrene-isobutylene block copolymer, and hydrogenated versions thereof. These may be used alone or in combination. The average molecular weight of the polystyrene-based thermoplastic elastomer is preferably high. It may also be extended with process oil before use. The polystyrene-based thermoplastic elastomer is used as is without undergoing a crosslinking reaction.

The amount of (A1) polyolefin is preferably 70 to 90 parts by weight, and the amount of (A2) rubber component and/or polystyrene thermoplastic elastomer is preferably 30 to 10 parts by weight per 100 parts by weight of the polymer composition.
When polypropylene and polyethylene are used as the polyolefin (A1) and (A2) is a rubber component, it is preferable that the polypropylene is 45 to 70 parts by weight, the polyethylene is 33 to 5 parts by weight (the total amount of polypropylene and polyethylene is 75 to 85 parts by weight), and the rubber component is 15 to 25 parts by weight.

In addition, a nonionic surfactant may be blended into the polymer composition. Examples of the nonionic surfactant include alkyl polyethers such as polyoxyethylene (polyoxypropylene) alkyl ethers, fatty acid polyether esters such as polyoxyethylene (polyoxypropylene) fatty acid esters, dipolyoxyethylene (dipolyoxypropylene) alkylamines such as di(dioxyethylene)stearylamine, polyoxyethylene (polyoxypropylene) dialkylamines, polyoxyethylene (polyoxypropylene) alkyl alkylenediamines, sorbitan esters such as polyoxyethylene (polyoxypropylene) sorbitan esters and sorbitan alkyl esters, polyoxyethylene (polyoxypropylene) alkyl glyceryl ethers, alkyl glyceryl polyethers or esters such as monoglyceryl stearate and polyoxyethylene (polyoxypropylene) fatty acid glyceryl, alkanolamides such as fatty acid (di)ethanolamides, and mixtures thereof. The number of carbon atoms in the alkyl, fatty acid, and alkylene is preferably 10 or more in terms of compatibility with the polyolefin polymer composition, and examples thereof include C12 (lauryl or laurate, etc.), C18 (stearyl or stearate, etc.), and C22 (behenyl or behenylate, etc.). The number of repeating units of oxyalkyl such as polyoxyethylene and polyoxypropylene is preferably 1 to 20, and more preferably 10 or less. The number of repeating units of polyglyceryl is also preferably 1 to 20, and more preferably 10 or less.
Furthermore, one or a mixture of alkyl polyether amines, fatty acid glyceryl, and fatty acid (di)ethanolamides can be preferably used, and higher alcohols such as stearyl alcohol may also be added.
On the other hand, anionic surfactants and cationic surfactants have problems such as not being able to form open cells, being poorly degradable, and being highly toxic, causing protein denaturation, skin disorders, and other human and environmental pollution problems.

When a nonionic surfactant is added, the amount of nonionic surfactant is preferably 0.2 to 10 parts by weight, more preferably 0.3 to 5 parts by weight, and even more preferably 0.5 to 3 parts by weight per 100 parts by weight of the polymer composition.

Optional ingredients that can be added to give the resulting foam suitable properties or to facilitate the production and processing of the foam include lubricants such as liquid paraffin, hydrocarbon processing oil, higher fatty acid glycerin esters, and higher fatty acid amides; flame retardants such as phosphate esters, melamine phosphate or piperazine phosphate, aluminum hydroxide, magnesium hydroxide, antimony oxide, zinc carbonate, chlorinated paraffins, and hexachlorocyclopentadiene; antioxidants such as aromatic amines, benzimidazoles, dithiocarbamates, phenolic compounds, and phosphites; and 2,6 It can also contain antioxidants such as 2,6-di-t-butylphenol, 2,6-di-t-butyl-4-ethylphenol, 4,4'-butylidenebis(3-methyl-6-t-butylphenol), and 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane; conductive materials such as conductive carbon black, copper powder, nickel powder, and tin oxide; colorants such as carbon black, organic pigments, dyes, and masterbatches containing these; and fillers such as silica, alumina, titanium oxide, and the various additives listed above that function as fillers.

The resin foam 11 may be either uncompressed or compressed and fixed, but compressed and fixed is more preferable. Compressing and fixing the resin foam 11 can further enhance light reflectivity. Compressing and fixing the resin foam 11 involves compressing the resin foam and then cooling it to fix the thickness at the time of compression. The heating temperature is set to 140 to 160°C, and hot compression processing is performed using rolls. The roll delivery speed is preferably 4 to 6 m/min. The compression rate (%), calculated by dividing the thickness after molding by the original thickness x 100, is preferably 40% or less, and more preferably 10 to 30%. The clearance between the rolls is preferably 0.4 mm or more.

The resin foam 11 consists of a single layer (one layer) or multiple layers (two or more layers). In the case of multiple layers, multiple resin foams are stacked and thermally compressed, fusion-bonding them together and then compressed and fixed.

The thickness of the light reflector 10, which is made of uncompressed or compressed and fixed resin foam 11, can be determined as appropriate, but is preferably 0.2 to 2.0 mm.

The light reflector 20 of the second embodiment shown in Figure 2 has a light-reflecting resin film 21 laminated on the surface of the resin foam 11. The resin foam 11 is the same as in the light reflector 10 of the first embodiment, and may be either uncompressed or compressed and fixed, and may be either a single layer (one layer) or multiple layers (two or more layers).

It is preferable to provide a light-reflecting resin film 21 on one side of the light reflector 20 so that light that enters the resin foam 11 from the surface on the side where the light-reflecting resin film 21 is not present is reflected by the light-reflecting resin film 21 on the opposite surface, thereby increasing the reflectivity of the light reflector 20.

The light-reflecting resin film 21 is preferably one in which a white pigment is dispersed in the resin, or a metal layer is vapor-deposited onto the resin film to impart light reflectivity. Examples of white pigments include titanium oxide. Furthermore, the resin constituting the resin film is preferably a thermoplastic resin such as vinyl chloride resin or olefin-based resin. From the perspective of improving flame retardancy, vinyl chloride resin is preferred. The white pigment content is preferably 1 to 10 parts by weight. The thickness of the light-reflecting resin film 21 is preferably 50 to 200 μm. If the thickness of the light-reflecting resin film 21 is too thin, light transmittance will increase, and conversely, if it is too thick, light diffusion will decrease.

The light reflecting resin film 21 may be laminated on the resin foam 11 by any of direct lamination, hot melt lamination, and extrusion lamination.
Direct lamination is a method in which a light-reflecting resin is extruded in the form of a film and directly laminated onto a resin foam 11 extruded from an extruder.
The hot melt lamination is Sekisui Fuller Co., Ltd. olefin-based hot melt JM-5009-F.
For the extrusion laminate, PA03A manufactured by SunAllomer Co., Ltd. was used.
When the resin foam 11 is compressed and fixed, the resin foam 11 may be compressed and fixed either before or after laminating the light reflecting resin film 21 .

<Example of First Embodiment>
An example of the light reflecting plate 10 of the first embodiment made of the resin foam 11 shown in FIG. 1 will be described below.
A polymer composition consisting of 50 parts by weight of homopolypropylene (product name: EA9, manufactured by Japan Polypropylene Corporation) as the polypropylene, 33 parts by weight of low-density polyethylene (product name: NUC8042, manufactured by NUC Corporation) as the polyethylene, 110°C, melting point: 110°C, and 17 parts by weight of EPDM as the rubber component was used, and two types of resin foams with thicknesses of 1.8 mm and 0.9 mm were formed by extrusion molding using a supercritical foam molding method, to construct the light reflectors of Examples 1 to 6 having the layer structure shown in Figure 4.

The polypropylene used was 70 parts by weight of random polypropylene (product name: PC630S, manufactured by SunAllomer Co., Ltd.) with a melting point of 160°C; the polyethylene used was 5 parts by weight of low-density polyethylene (product name: NUC8042, manufactured by NUC Co., Ltd.) with a melting point of 110°C; and the polystyrene-based thermoplastic elastomer used was 25 parts by weight of SEBS (hydrogenated styrene-butadiene reblock polymer, product name: Tuftec H1062, manufactured by Asahi Kasei Corporation) with a styrene content of 20% and a number-average molecular weight of 100,000. This polymer composition was extruded using a supercritical foam molding method to form a resin foam with a thickness of 1.8 mm, and the light reflector of Example 7, with the layer structure shown in Figure 4, was constructed. Example 7 is an example in which a polystyrene-based thermoplastic elastomer (SEBS) was blended in place of the EPDM (rubber component) used in Examples 1 to 6.

In addition, an ultrafine foam light reflector (product name: MCPET, manufactured by Furukawa Electric Co., Ltd.) was prepared as the light reflector for Comparative Example 1, and a reflective film (product name: Lumirror E60V, manufactured by Toray Industries, Inc.) was prepared as the light reflector for Comparative Example 2.

The light reflectance of the light reflectors of each example and each comparative example was measured in the wavelength range of 300 to 780 μm. Light reflectance was measured using a UV-Visible-Near-Infrared Spectrophotometer V-650 (manufactured by JASCO Corporation), with a measurement wavelength range of 300 to 780 nm, light sources of deuterium (D2) lamp and tungsten (WI) lamp, and a standard white plate of barium sulfate. Three samples were used.

Example 1 had a thickness of 1.8 mm after molding, was not compressed and fixed, and had a single layer structure with an original thickness of 1.8 mm. The maximum light reflectance (MAX) was 92.49%, the minimum light reflectance (MIN) was 82.10%, the difference between the maximum and minimum values (R) was 10.39, the average light reflectance was 89.87%, the standard deviation σ was 2.09, and the standard deviation 3σ was 6.27.

Example 2 had a thickness of 0.9 mm after molding, was not compressed and fixed, and had a single layer structure with an original thickness of 0.9 mm. The MAX light reflectance was 83.02%, the MIN was 77.81%, R was 5.20, the average light reflectance was 80.23%, the standard deviation σ was 1.14, and the standard deviation 3σ was 3.42.

Example 3 has a post-molding thickness of 0.5 mm, is compressed and fixed, has a single layer structure with an original thickness of 1.8 mm, a compression rate of 28%, a MAX light reflectance of 93.81%, a MIN light reflectance of 83.90%, an R value of 9.91, an average light reflectance of 91.09%, a standard deviation σ of 1.87, and a standard deviation 3σ of 5.61.

Example 4 has a post-molding thickness of 0.25 mm, is compressed and fixed, has a single layer structure with an original thickness of 1.8 mm, a compression rate of 14%, a MAX light reflectance of 91.70%, a MIN light reflectance of 81.28%, an R light reflectance of 10.43, an average light reflectance of 87.99%, a standard deviation σ of 1.82, and a standard deviation 3σ of 5.46.

Example 5 has a post-molding thickness of 0.5 mm, is compressed and fixed, has a two-layer structure with an original thickness of 1.8 mm + 1.8 mm, a compression rate of 13%, a MAX light reflectance of 98.12%, a MIN light reflectance of 84.59%, R of 13.53, an average light reflectance of 94.92%, a standard deviation σ of 2.71, and a standard deviation 3σ of 8.13.

Example 6 has a post-molding thickness of 0.25 mm, is compressed and fixed, has a two-layer structure with an original thickness of 1.8 mm + 0.9 mm, a compression rate of 9%, a MAX light reflectance of 88.11%, a MIN light reflectance of 74.57%, an R value of 13.54, an average light reflectance of 84.76%, a standard deviation σ of 2.58, and a standard deviation 3σ of 7.73.

Example 7 has a post-molding thickness of 0.5 mm, is compressed and fixed, has a single layer structure with an original thickness of 1.8 mm, a compression rate of 28%, a MAX light reflectance of 5.76%, a MIN light reflectance of 35.59%, an R value of 46.16, an average light reflectance of 80.35%, a standard deviation σ of 10.64, and a standard deviation 3σ of 31.91.

Comparative example 1 has a thickness of 0.5 mm, a MAX light reflectance of 98.87%, a MIN of -3.95%, R of 102.82, an average light reflectance of 80.84%, a standard deviation σ of 34.84, and a standard deviation 3σ of 104.51. Note that the minimum light reflectance (MIN) is a negative value, which suggests that light is transmitted.

Comparative example 2 had a thickness of 0.25 mm, a MAX light reflectance of 100.98%, a MIN light reflectance of 4.52%, an R of 96.46, an average light reflectance of 81.62%, a standard deviation σ of 33.79, and a standard deviation 3σ of 101.36.

The light reflectors of Examples 1 to 7 have the same or higher average light reflectance in the wavelength range of 300 to 780 μm as the light reflectors of Comparative Examples 1 and 2, demonstrating excellent light reflectivity. Furthermore, the light reflectors of Examples 1 to 7 have a smaller standard deviation 3σ of light reflectance than the light reflectors of Comparative Examples 1 and 2, meaning that the reflected light is scattered with a uniform illuminance, resulting in high-quality reflected light.

In addition, by varying the blending ratio of polypropylene and polyethylene in Examples 1 to 6, light reflectors were formed from the resin foam of Examples 8 to 12 shown in Figure 5. The amount of homopolypropylene (polypropylene) varied from 45 to 65 parts by weight, the amount of low-density polyethylene (polyethylene) varied from 20 to 40 parts by weight, and the amount of EPDM (rubber component) varied from 15 to 35 parts by weight. When the light reflectance of each sample was measured without compressing and fixing it to a thickness of 1.8 mm, the MAX (maximum value) of the light reflectance was 90% or more, the MIN (minimum value) was 80% or more, and the 3σ was 10 or less. The block polypropylene used in Example 12 had a melting point of 162°C and was product name: EC9, manufactured by Japan Polypropylene Corporation.

For the resin foams of Examples 1 to 12 (before compression), cross sections cut along the thickness direction were photographed using a microscope, and the diameters of 30 bubbles were measured from the obtained images. The average values were all between 5 and 250 μm, and the bubble diameter increased from the surface toward the interior of the resin foam.

<Example of the second embodiment>
An example of the light reflector 20 of the second embodiment, which is made of a laminate of the resin foam 11 and the light reflecting resin film 21 shown in FIG. 2, will be described below.
Two types of resin foams with thicknesses of 1.8 mm and 0.9 mm were formed by extrusion molding using a supercritical foam molding method from polymer compositions with the same formulations as in Examples 1 to 6 of the first embodiment, and a light-reflecting resin film was laminated onto the resin foams by direct lamination to obtain the light reflectors of Examples 13 to 17 shown in Figure 6. For examples requiring compression fixation of the resin foam, compression fixation was performed on the resin foam after lamination of the light-reflecting resin film. For comparison, Figure 6 also shows Examples 1, 3, 5, and 7 of the first embodiment and Comparative Examples 1 and 2, which are not laminated with a light-reflecting resin film.

Three types of light-reflecting resin films were used: A, B, and C. Light-reflecting resin film A is a 100μm thick polypropylene resin film containing 10% by weight of white pigment, a prototype manufactured by I-Sheet. Light-reflecting resin film B is a 60μm thick vinyl chloride resin film manufactured by 3M under the product name Diffuser Film 3635-70. Light-reflecting resin film C is a 60μm thick vinyl chloride resin film containing titanium oxide, under the product name Diffuser Film 3635-300, manufactured by 3M.

The light reflectance of the light reflectors of Examples 13 to 17 was measured in the wavelength range of 300 to 780 μm. Light reflectance was measured using a UV-Visible-Near-Infrared Spectrophotometer V-650 (manufactured by JASCO Corporation) with a measurement wavelength range of 300 to 780 nm, a deuterium (D2) lamp and a tungsten (WI) lamp as light sources, and a barium sulfate standard white plate. Three samples were used. Light reflectivity was evaluated based on light reflectance. A rating of "◎" was given when the light reflectance was 80% or greater in all regions at 300 nm, 555 nm, and 780 nm. A rating of "〇" was given when the light reflectance was 30% or greater in all regions at 300 nm, 555 nm, and 780 nm, but less than 80% in any of those regions. A rating of "X" was given when the light reflectance was less than 30% in any of the regions at 300 nm, 555 nm, and 780 nm.

Flamme retardancy was also measured for the light reflectors of Examples 13 to 17, Examples 1, 3, 5, and 7 of the first embodiment, and Comparative Examples 1 and 2. Flame retardancy was measured based on the HBF test of the UL94 flame retardancy standard, and samples that met the HBF test criteria (burning rate between 100 mm marked lines of 40 mm/min or less, or burning distance of less than 125 mm) were rated as passing; samples that did not meet the HBF test criteria were rated as failing.

In Example 13, the light-reflecting resin film A had a thickness of 100 μm, the resin foam was the same as in Example 3, the thickness after molding was 0.5 mm, there was compression fixing, the layer structure was a single layer with an original thickness of 1.8 mm, and the compression rate was 28%.
The light reflectance of Example 13 was 85% at 300 nm, 97% at 555 nm, and 98% at 780 nm, and the light reflectivity was rated as "Excellent" and the flame retardancy was judged to be "Pass".
The light reflector of Example 13 had higher light reflectance and better flame retardancy than the light reflector of Example 3, which had the same resin foam structure but no light-reflecting resin film laminated thereon.

Example 14 has a light-reflecting resin film A, a light-reflecting resin film having a thickness of 100 μm, a resin foam similar to that of Example 5, a thickness of 0.5 mm after molding, compression fixing, a layer structure of two layers with an original thickness of 1.8 mm + 1.8 mm, and a compression rate of 13%.
The light reflectance of Example 14 was 85% at 300 nm, 98% at 555 nm, and 99% at 780 nm, and the light reflectivity was rated as "Excellent" and the flame retardancy was judged to be "Pass".
The light reflector of Example 14 had higher light reflectance and better flame retardancy than the light reflector of Example 5, which had the same resin foam structure but no light-reflecting resin film laminated thereon.

Example 15 is a light-reflecting resin film B, the thickness of the light-reflecting resin film is 70 μm, the resin foam is the same as that of Example 3, the thickness after molding is 0.5 mm, there is compression fixing, the layer structure is a single layer with an original thickness of 1.8 mm, and the compression rate is 28%.
The light reflectance of Example 15 was 94% at 300 nm, 98% at 555 nm, and 98% at 780 nm, and the light reflectance was rated as "Excellent" and the flame retardancy was judged to be "Pass".
The light reflector of Example 15 had higher light reflectance and better flame retardancy than the light reflector of Example 3, which had the same resin foam structure but no light-reflecting resin film laminated thereon.

Example 16 is a light-reflecting resin film B, the thickness of the light-reflecting resin film is 70 μm, the resin foam is the same as that of Example 5, the thickness after molding is 0.5 mm, there is compression fixing, the layer structure is two layers of original thickness 1.8 mm + 1.8 mm, and the compression rate is 13%.
The light reflectance of Example 16 was 85% at 300 nm, 98% at 555 nm, and 99% at 780 nm, and the light reflectivity was rated as "Excellent" and the flame retardancy was judged to be "Pass".
The light reflector of Example 16 had higher light reflectance and better flame retardancy than the light reflector of Example 5, which had the same resin foam structure but no light-reflecting resin film laminated thereon.

Example 17 is a light-reflecting resin film C, the thickness of the light-reflecting resin film is 30 μm, the resin foam is the same as that of Example 3, the thickness after molding is 0.5 mm, there is compression fixing, the layer structure is a single layer with an original thickness of 1.8 mm, and the compression rate is 28%.
The light reflectance of Example 16 was 83% at 300 nm, 95% at 555 nm, and 95% at 780 nm, and the light reflectivity was rated as "Excellent" and the flame retardancy was judged to be "Pass".
The light reflector of Example 16 had higher light reflectance and better flame retardancy than the light reflector of Example 3, which had the same resin foam structure but no light-reflecting resin film laminated thereon.

As shown in Figure 6, Examples 1, 3, 5, and 7, which were not laminated with a light-reflecting resin film, all achieved a "fail" rating for flame retardancy. Furthermore, Comparative Examples 1 and 2 achieved a "pass" rating for flame retardancy, but had poor light reflectivity at 300 nm, resulting in a light reflectivity rating of "x."

As described above, the light reflecting plate of the present invention has excellent light reflectivity and can provide high-quality reflected light.
The light reflecting plate of the present invention, which has excellent light reflectivity, is suitable for a backlight type surface illumination device in which light is reflected and diffused within the housing.

10, 20 Light reflecting plate 11 Resin foam 13 Air bubbles 15 Skin layer 21 Light reflecting resin film

Claims (2)

Polyolefin and
a resin foam of a polymer composition containing a rubber component and/or a polystyrene-based thermoplastic elastomer,
The resin foam is a light reflector having a bubble diameter of 5 to 250 μm, or
Polyolefin and
A light reflector made of a resin foam of a polymer composition containing at least one of EPR (EPM), which is a copolymer of ethylene and propylene, isoprene-butadiene rubber, and ethylene-propylene-diene copolymer rubber (EPDM),
The resin foam comprises a compressed resin foam having a skin layer on the surface , and the bubble diameter before compression is 5 to 250 μm, and the bubble diameter increases from the surface toward the inside . Polyolefin and
a resin foam of a polymer composition containing a rubber component and/or a polystyrene-based thermoplastic elastomer,
The resin foam is a light reflector having a bubble diameter of 5 to 250 μm, or
Polyolefin and
A light reflector made of a resin foam of a polymer composition containing at least one of EPR (EPM), which is a copolymer of ethylene and propylene, isoprene-butadiene rubber, and ethylene-propylene-diene copolymer rubber (EPDM),
The resin foam comprises two compressed resin foams each having a skin layer on the surface , and the bubble diameter before compression is 5 to 250 μm, and the bubble diameter increases from the surface toward the inside .