WO2013111717A1

WO2013111717A1 - Foam diffuse reflector

Info

Publication number: WO2013111717A1
Application number: PCT/JP2013/051128
Authority: WO
Inventors: 平尾　昭; 智紀兵藤
Original assignee: 日東電工株式会社
Priority date: 2012-01-24
Filing date: 2013-01-22
Publication date: 2013-08-01
Also published as: JP2013152271A; TW201335615A

Abstract

The purpose of the present invention is to provide a foam diffuse reflector that has a minutely controlled bubble structure with high air content and multiple minutely controlled fine surface openings, and exhibits excellent diffuse reflection, as well as excellent heat resistance and mechanical strength. The foam diffuse reflector according to the present invention includes a foam body which has a continuous bubble structure having through-holes between adjoining spherical bubbles, and the foam body includes a hydrophilic <span style='font-family:"Courier New"'>polyurethane</span> polymer. The average bubble diameter of the spherical bubbles is less than 20 μm and the average pore diameter of the through-holes is 5 µm or less. The foam body has surface openings with an average pore diameter of 20 µm or less on the surface thereof, and the diffuse reflection ratio within the wavelength range of 400 nm to 600 nm is 90% or more.

Description

Foam diffuse reflector

The present invention relates to a foamed diffuse reflector. In detail, it is related with the foaming diffused reflection body which has the special foaming surface structure formed by including specific resin.

Diffuse reflectors are provided in various light sources (for example, LED substrates, backlight devices for liquid crystal display devices, lighting devices such as fluorescent lamps, incandescent lamps, and light duct system devices such as natural lighting), and due to their diffuse reflection performance, Luminous efficiency from a device using an external light source is improved.

Usually, a diffuse reflector is required to have high diffuse reflection performance.

As a diffuse reflector with high diffuse reflection performance, the film contains a diffuse reflector formed by depositing a metal vapor-deposited film on the surface of a substrate such as metal to form a metal mirror surface, or a pigment or fine particles that enhance light scattering. Diffuse reflectors are known. However, the diffuse reflector formed with the metal mirror surface has a problem that the light scattering performance is low although the light reflecting performance is high. In addition, a diffuse reflector in which a film containing pigments and fine particles that enhance light scattering properties needs to increase the amount of pigments and fine particles added in order to suppress the leakage of light to the back side, There is a problem in that the loss due to light absorption cannot be ignored and the light reflection performance decreases as the amount of pigment or fine particles added increases.

A polyester foam containing fine bubbles has been reported as a new diffuse reflector (for example, Patent Document 1). This diffuse reflector utilizes the property that light is diffusely reflected by a large number of fine bubbles.

However, the polyester foam reported in Patent Document 1 has fine bubbles arranged inside the polyester foam and has an unfoamed skin layer near both surfaces. For this reason, there is a problem that fine bubbles do not exist in the vicinity of both surfaces, and sufficient diffuse reflection performance cannot be exhibited.

Furthermore, in recent years, light sources (for example, LEDs) have become more bright, and accordingly, the amount of heat generated from the light sources has increased, and the heat load on the reflector has also increased. Further, in addition to the LED light source, a diffuse reflector used in a natural light daylight duct device or the like deteriorates the diffuse reflection performance due to yellowing or deformation. For example, the diffuse reflector used in the device has light resistance. In addition, high heat resistance is required to prevent dimensional changes due to heat or the like.

Japanese Patent Publication No. 97/1117

An object of the present invention is a foamed diffuse reflector having a cell structure, the cell structure is precisely controlled, the cell rate is high, and has a large number of finely controlled surface openings. An object of the present invention is to provide a foamed diffuse reflector that can exhibit very excellent diffuse reflection performance and has excellent heat resistance and light resistance.

The foamed diffuse reflector of the present invention includes a foam having an open cell structure having through-holes between adjacent spherical cells, the foam includes a hydrophilic polyurethane polymer, and the average pore size of the spherical cells is 20 μm. The average pore diameter of the through-holes is 5 μm or less, the surface of the foam has a surface opening with an average pore diameter of 20 μm or less, and the diffuse reflectance in the wavelength region of 400 nm to 600 nm is 90% or more. is there.

In a preferred embodiment, the foamed diffuse reflector of the present invention has a thickness of 0.1 mm or more.

In a preferred embodiment, the foamed diffuse reflector of the present invention has a dimensional change rate of less than ± 5% when stored at 125 ° C. for 22 hours.

In a preferred embodiment, the foamed diffuse reflector of the present invention has a reflectance decrease of less than 10% at a wavelength of 550 nm before and after irradiation with ultraviolet rays having an illuminance of 90 mW / cm ² for 100 hours.

In a preferred embodiment, a light shielding layer is further provided on the surface opposite to the reflecting surface of the foamed diffuse reflector.

In a preferred embodiment, the foamed diffuse reflector of the present invention has a hole penetrating in the thickness direction of the foam diffuse reflector, and the diameter of the hole penetrating in the thickness direction is 20 mm to 60 mm.

According to another aspect of the present invention, a method for producing a foamed diffuse reflector is provided. The production method is a method of producing a foamed diffuse reflector including a foam having an open cell structure having a through-hole between adjacent spherical cells, the continuous oil phase component being immiscible with the continuous oil phase component The step (I) of preparing a W / O type emulsion containing the aqueous phase component, the step (II) of shaping the obtained W / O type emulsion, and polymerizing the shaped W / O type emulsion The step (III) and the step (IV) of dehydrating the obtained water-containing polymer are included, and the continuous oil phase component includes a hydrophilic polyurethane-based polymer, an ethylenically unsaturated monomer, and a crosslinking agent.

In a preferred embodiment, the crosslinking agent has at least one selected from polyfunctional (meth) acrylates, polyfunctional (meth) acrylamides, and polymerization reactive oligomers having a weight average molecular weight of 800 or more, and a weight average molecular weight. 1 or more types chosen from polyfunctional (meth) acrylate and polyfunctional (meth) acrylamide which are 500 or less are included.

In a preferred embodiment, the foamed diffuse reflector is obtained by the production method.

According to the present invention, the foam diffuse reflector having a cell structure, the cell structure is precisely controlled, the cell rate is high, and has a number of fine surface openings that are precisely controlled, It is possible to provide a foamed diffuse reflector that can exhibit very excellent diffuse reflection performance and has excellent heat resistance and light resistance. Since the foamed diffuse reflector of the present invention is excellent in dimensional stability even at high temperatures, it can maintain excellent diffuse reflection performance even at high temperatures, and can be preferably used for, for example, an LED substrate.

It is a schematic sectional drawing which shows preferable embodiment of the foaming diffused reflection body of this invention. It is a schematic sectional drawing which shows another preferable embodiment of the foaming diffused reflection body of this invention. It is a photograph figure of a section SEM photograph of a foaming diffused reflector of the present invention, and is a photograph figure clearly showing open cell structure which has a penetration hole between adjacent spherical bubbles. (A) is a foaming diffused reflection body by one Embodiment of this invention, and is a schematic sectional drawing which shows the foaming diffused reflection body which has an inclination through-hole. (B) is a schematic cross-sectional perspective view of the inclined through-hole. It is a photograph figure of the surface / cross-section SEM photograph which image | photographed the foaming diffused reflection body produced in Example 1 from diagonally.

≪ << A. Foam diffuse reflector >>>>
The foaming diffused reflection body of this invention contains the foam containing a hydrophilic polyurethane type polymer, and this foam has an open-cell structure which has a through-hole between adjacent spherical cells. Typical structures include a foam diffuse reflector 100 (FIG. 1) made of the foam 10, and a foam diffuse reflector 100 (FIG. 2) including a base material 20 (described later) between the foam 10a and the foam 10b. ). In FIG. 1 and FIG. 2, the release film 30 is provided for protecting the surface of the foaming diffuse reflector, but the release film may not be provided.

The thickness of the foamed diffuse reflector of the present invention is preferably 0.1 mm or more, more preferably 0.1 mm to 10 mm, still more preferably 0.2 mm to 5 mm, particularly preferably 0.2 mm to 1 mm. It is. The foamed diffuse reflector of the present invention is excellent in mechanical strength even if it is thin.

In the present specification, the “spherical bubble” does not have to be a strict true spherical bubble, and may be, for example, a substantially spherical bubble having a partial strain or a bubble composed of a space having a large strain. .

The average pore diameter of the spherical bubbles that the foam contained in the foamed diffuse reflector of the present invention may have is less than 20 μm, preferably 15 μm or less, more preferably 10 μm or less. The lower limit value of the average pore diameter of the spherical bubbles of the foam contained in the foamed diffuse reflector of the present invention is not particularly limited. For example, it is preferably 0.01 μm, more preferably 0.1 μm, and still more preferably. 1 μm. When the average pore diameter of the spherical bubbles contained in the foamed diffuse reflector of the present invention falls within the above range, the average pore diameter of the spherical bubbles of the foam contained in the foamed diffuse reflector of the present invention is precisely reduced. A novel foamed diffuse reflector that can be controlled and is excellent in flexibility and heat resistance can be provided.

The foam contained in the foamed diffuse reflector of the present invention has an open cell structure having through holes between adjacent spherical cells. This open cell structure may be an open cell structure having through holes between most or all adjacent spherical cells, or may be a semi-independent semi-open cell structure having a relatively small number of through holes. . By using a foam having such an open cell structure, the foamed diffuse reflector of the present invention can have a sufficient adhesive force. This is because, when the foam diffuse reflector is pressed against the adherend, the spherical bubbles and the through holes are compressed, and air is released from the foam surface to the outside. Is presumed to be exhibited. Specifically, since the open cell structure extends in all directions inside the foam, air easily escapes outward by pressing. As a result, it is presumed that a sufficient atmospheric pressure difference is generated and excellent adsorptivity is exhibited. Moreover, as above-mentioned, since the adhesive force of the foaming diffused reflection body of this invention utilizes adsorption power, peeling and sticking are possible any number of times. Since such a foaming diffused reflector is easy to attach and excellent in reworkability, for example, when used in an LED substrate or a backlight device, it can contribute to improvement in workability at the time of manufacture.

The through hole between adjacent spherical bubbles affects the physical properties of the foam diffuse reflector. For example, the strength of the foamed diffuse reflector tends to increase as the average hole diameter of the through holes decreases. FIG. 3 is a photographic view of a cross-sectional SEM photograph of the foamed diffuse reflector of the present invention, and shows a photographic view clearly showing an open cell structure having through holes between adjacent spherical bubbles.

The average pore diameter of the through holes between adjacent spherical bubbles is 5 μm or less, preferably 4 μm or less, more preferably 3 μm or less. The lower limit value of the average pore diameter of the through holes between adjacent spherical bubbles is not particularly limited, and is preferably 0.001 μm, and more preferably 0.01 μm, for example. When the average pore diameter of the through holes between adjacent spherical bubbles is within the above range, a novel foamed diffuse reflector having excellent flexibility and heat resistance can be provided.

The foam contained in the foamed diffuse reflector of the present invention has a surface opening on the surface. The average pore diameter of the surface opening is 20 μm or less, preferably less than 20 μm, more preferably 15 μm or less, further preferably 10 μm or less, further preferably 5 μm or less, and particularly preferably 4 μm or less. And most preferably 3 μm or less. The lower limit of the average pore diameter of the surface opening is not particularly limited, and is preferably 0.001 μm, and more preferably 0.01 μm, for example. When the foam contained in the foamed diffuse reflector of the present invention has a surface opening, and the average pore diameter of the surface opening is within the above range, very excellent diffuse reflection performance can be expressed.

The density of the foam contained in the foamed diffuse reflector of the present invention is preferably 0.15 g / cm ³ to 0.6 g / cm ³ , more preferably 0.15 g / cm ³ to 0.5 g / cm ^3. , and still more preferably from ^{0.15g / cm 3 ~ 0.45g / cm} 3, particularly preferably from ^{0.15g / cm 3 ~ 0.4g / cm} 3. When the density of the foam contained in the foamed diffuse reflector of the present invention falls within the above range, the range of density of the foam contained in the foamed diffuse reflector of the present invention is widely controlled, and flexibility and diffusion are achieved. A novel foaming diffused reflector excellent in reflectivity can be provided.

The foam contained in the foamed diffuse reflector of the present invention has a cell ratio of preferably 30% or more, more preferably 40% or more, and further preferably 50% or more. In the foamed diffuse reflector of the present invention, the foam ratio falls within the above range, so that the foam diffused reflector of the present invention can exhibit very excellent diffuse reflective performance, and has excellent flexibility and excellent diffuse reflectivity. Can have.

The foam contained in the foamed diffuse reflector of the present invention contains a hydrophilic polyurethane polymer. Since the foam contained in the foamed diffuse reflector of the present invention contains a hydrophilic polyurethane polymer, the cell structure is precisely controlled, the cell rate is high, and a large number of fine surface openings controlled precisely. It is possible to provide a novel foamed diffuse reflector that has a portion, can exhibit very excellent diffuse reflection performance, and has excellent flexibility and excellent heat resistance.

The details of the foam contained in the foamed diffuse reflector of the present invention and the details of the hydrophilic polyurethane polymer contained therein will be mentioned in the description of the production method described later.

In the foamed diffuse reflector of the present invention, the diffuse reflectance in the wavelength region of 400 nm to 600 nm is preferably 90% or more, more preferably 95% or more, still more preferably 98% or more, and particularly preferably. It is 99% or more, and most preferably 99.5% or more.

The foamed diffuse reflector of the present invention has a decrease in reflectance at a wavelength of 550 nm before and after being irradiated with ultraviolet rays having an illuminance of 90 mW / cm ² for 100 hours, preferably less than 20%, more preferably less than 10%, More preferably, it is less than 5%. When the reduction in reflectance before and after the ultraviolet irradiation falls within the above range, the foamed diffuse reflector of the present invention can have very excellent light resistance.

The foamed diffuse reflector of the present invention has a normal shear adhesive strength of preferably 1 N / cm ² or more, more preferably 3 N / cm ² or more, still more preferably 5 N / cm ² or more, and further preferably 7 N / cm ² or more, particularly preferably 9 N / cm ² or more, and most preferably 10 N / cm ² or more. When the normal shear adhesive strength falls within the above range, the foamed diffuse reflector of the present invention can exhibit sufficient adhesive strength.

The foamed diffuse reflector of the present invention has a 180 ° peel test force of preferably 1 N / 25 mm or less, more preferably 0.8 N / 25 mm or less, still more preferably 0.5 N / 25 mm or less. Preferably it is 0.3 N / 25 mm or less. When the 180 ° peel test force is within the above range, the foamed diffuse reflector of the present invention exhibits an excellent effect that it can be easily peeled despite its high adhesive strength as described above. obtain.

The foamed diffuse reflector of the present invention has a 100 ° C. holding force of preferably 0.5 mm or less, more preferably 0.4 mm or less, still more preferably 0.3 mm or less, and particularly preferably 0.2 mm. It is as follows. When the 100 ° C. holding force falls within the above range, the foamed diffuse reflector of the present invention can achieve both excellent heat resistance and sufficient adhesive strength.

In the foamed diffuse reflector of the present invention, the dimensional change rate when stored at 125 ° C. for 22 hours is preferably less than ± 5%, more preferably ± 3% or less, and further preferably ± 1% or less. is there. In the foamed diffuse reflector of the present invention, the dimensional change rate when stored at 125 ° C. for 22 hours is within the above range, whereby the foamed diffuse reflector of the present invention can have excellent heat resistance. Such a foamed diffuse reflector can prevent changes in reflection characteristics even at high temperatures.

The foamed diffuse reflector of the present invention can take any appropriate shape. In the foaming diffused reflection body of this invention, lengths, such as a long side and a short side, can take arbitrary appropriate values.

In one embodiment, the foamed diffuse reflector of the present invention is used for an LED substrate (for example, an LED substrate of a direct type backlight device). The foaming diffused reflector of the present invention can be used as an LED substrate itself, and can also be used as a reflector laminated on the LED substrate. When used as a reflector laminated on an LED substrate, the foamed diffuse reflector of the present invention is provided so as to allow the LED to pass through at a position corresponding to the LED on the LED substrate. May have a hole). The through hole can be obtained, for example, by perforating a foamed diffuse reflector obtained by polymerizing a W / O emulsion as described later by a known counterbore processing method. The plan view shape of the through hole may be a substantially circular shape or a substantially regular polygon. Preferably it is substantially circular. When the through hole has a substantially circular shape in plan view, the diameter is preferably 20 mm to 60 mm, more preferably 25 mm to 40 mm. When the through hole has a substantially regular polygonal shape in plan view, the diameter of a circle inscribed in the substantially regular polygon is preferably 20 mm to 60 mm, and more preferably 25 mm to 40 mm.

When the foamed diffuse reflection pair of the present invention is used as a reflector laminated on the LED substrate as described above, the through holes of the foamed diffuse reflector are preferably shown in FIGS. 4 (a) and 4 (b). As shown, it is an inclined through hole that forms a mortar-shaped inclined surface on the inside. FIG. 4A is a schematic perspective view of a foamed diffuse reflector according to one embodiment of the present invention, showing a foamed diffuse reflector having inclined through holes. FIG. 4B is a schematic cross-sectional perspective view of the inclined through hole. If it has the inclined through-hole 1, since the light from LED can be reflected by making an inclined surface into a reflective surface, the foaming diffused reflection body which can express the outstanding diffuse reflection performance can be provided. The inclined through hole 1 is provided at a position corresponding to the LED on the LED substrate. In FIG. 4A, a plurality of inclined through holes 1 are shown, but one inclined through hole 1 may be provided according to the number of LEDs on the LED substrate. The opening of the inclined through hole 1 may be substantially circular or substantially regular polygonal on both the upper and lower sides. Preferably, it is substantially circular as shown in FIGS. 4 (a) and 4 (b). When the upper opening of the inclined through hole 1 is substantially circular, the diameter a of the upper opening is preferably 25 mm to 60 mm, more preferably 30 mm to 40 mm. When the lower opening of the inclined through hole 1 is substantially circular, the diameter b of the lower opening is shorter than the diameter a of the upper opening, preferably 20 mm to 40 mm, more preferably 20 mm to 30 mm. . When the upper opening of the inclined through hole 1 is a substantially regular polygon, the diameter of a circle inscribed in the substantially regular polygon is preferably 25 mm to 60 mm, and more preferably 30 mm to 40 mm. When the lower opening of the inclined through hole 1 is a substantially regular polygon, the diameter of a circle inscribed in the substantially regular polygon is preferably 20 mm to 40 mm, and more preferably 20 mm to 30 mm. The inclination angle x of the inclined surface of the inclined through hole 1 is preferably 5 ° to 80 °, more preferably 15 ° to 70 °, and further preferably 25 ° to 60 °.

In another embodiment, the foamed diffuse reflector of the present invention is used as a diffuse reflector for an edge light type backlight device and a lighting fixture. When used for an edge light type backlight device, it is not necessary to provide a through hole. Further, when used as a diffuse reflector for illumination, a through hole can be provided as necessary. The surface of the foamed diffuse reflector can be a flat surface or an uneven surface.

The foamed diffuse reflector of the present invention may contain any appropriate base material as long as the effects of the present invention are not impaired. As a form in which the base material is contained in the foamed diffuse reflector of the present invention, for example, a form in which a layer of the base material is provided in one surface or inside of the foamed diffuse reflector can be mentioned. Examples of such a substrate include fiber woven fabric, fiber nonwoven fabric, fiber laminated fabric, fiber knitted fabric, resin sheet, metal foil film sheet, and inorganic fiber. In one embodiment, the substrate is a light shielding layer. In this embodiment, as the base material (light shielding layer), for example, a metallic processed resin sheet, a metal foil film sheet, or the like is used, and the base material (light shielding layer) is opposite to the reflecting surface of the foaming diffuse reflector. On the side surface.

As the fiber woven fabric, a woven fabric formed of any appropriate fiber can be adopted. Examples of such fibers include natural fibers such as plant fibers, animal fibers, and mineral fibers; artificial fibers such as regenerated fibers, synthetic fibers, semi-synthetic fibers, and artificial inorganic fibers. Examples of synthetic fibers include fibers obtained by melt spinning thermoplastic fibers. Further, the fiber woven fabric may be metallic processed by plating or sputtering.

As the fiber nonwoven fabric, a nonwoven fabric formed of any appropriate fiber can be adopted. Examples of such fibers include natural fibers such as plant fibers, animal fibers, and mineral fibers; artificial fibers such as regenerated fibers, synthetic fibers, semi-synthetic fibers, and artificial inorganic fibers. Examples of synthetic fibers include fibers obtained by melt spinning thermoplastic fibers. Moreover, the fiber nonwoven fabric may be metallic-processed by plating, sputtering, etc. More specifically, for example, a spunbond nonwoven fabric can be mentioned.

As the fiber laminated fabric, a laminated fabric formed of any appropriate fiber can be adopted. Examples of such fibers include natural fibers such as plant fibers, animal fibers, and mineral fibers; artificial fibers such as regenerated fibers, synthetic fibers, semi-synthetic fibers, and artificial inorganic fibers. Examples of synthetic fibers include fibers obtained by melt spinning thermoplastic fibers. In addition, the fiber laminated fabric may be metallic processed by plating, sputtering, or the like. More specifically, for example, a polyester fiber laminated fabric can be mentioned.

As the fiber knitted fabric, for example, a knitted fabric formed of any appropriate fiber can be adopted. Examples of such fibers include natural fibers such as plant fibers, animal fibers, and mineral fibers; artificial fibers such as regenerated fibers, synthetic fibers, semi-synthetic fibers, and artificial inorganic fibers. Examples of synthetic fibers include fibers obtained by melt spinning thermoplastic fibers. Further, the fiber knitted fabric may be metallically processed by plating or sputtering.

As the resin sheet, a sheet formed of any appropriate resin can be adopted. An example of such a resin is a thermoplastic resin. The resin sheet may be metallic processed by plating or sputtering. When the resin sheet is subjected to metallic processing, the resin sheet functions as a light shielding layer.

As the metal foil film sheet, a sheet formed of any appropriate metal foil film can be adopted.

Any appropriate inorganic fiber can be adopted as the inorganic fiber. Specific examples of such inorganic fibers include glass fibers, metal fibers, and carbon fibers.

In the foamed diffuse reflector of the present invention, when there are voids in the substrate, the same material as the foamed diffuse reflector may be present in part or all of the voids.

The substrate may be used alone or in combination of two or more.

≪≪B. Manufacturing method of foamed diffuse reflector >>>>
The foaming diffuse reflector of this invention can be manufactured by arbitrary appropriate methods. The foamed diffuse reflector of the present invention can be preferably produced by shaping and polymerizing a W / O emulsion.

As a method for producing the foamed diffuse reflector of the present invention, for example, a W / O type that can be used to continuously supply a continuous oil phase component and an aqueous phase component to an emulsifier to obtain the foamed diffuse reflector of the present invention. There is a “continuous method” in which an emulsion is prepared, and then the obtained W / O emulsion is polymerized to produce a water-containing polymer, and then the obtained water-containing polymer is dehydrated. As a method for producing the foamed diffuse reflector of the present invention, for example, an appropriate amount of an aqueous phase component is charged into an emulsifier with respect to the continuous oil phase component, and the aqueous phase component is continuously supplied while stirring. A W / O emulsion that can be used to obtain the foamed diffuse reflector of the present invention is prepared, and the resulting W / O emulsion is polymerized to produce a hydrous polymer, followed by the hydrous weight obtained. A “batch method” in which the coalescence is dehydrated can be mentioned.

A continuous polymerization method in which a W / O emulsion is continuously polymerized is a preferable method because it has high production efficiency and can most effectively utilize the effect of shortening the polymerization time and the shortening of the polymerization apparatus.

More specifically, the foamed diffuse reflector of the present invention is preferably
Step (I) of preparing a W / O type emulsion that can be used to obtain the foamed diffuse reflector of the present invention;
Step (II) of shaping the obtained W / O emulsion,
Polymerizing the shaped W / O emulsion (III);
Step (IV) of dehydrating the obtained hydrous polymer;
It can manufacture with the manufacturing method containing. Here, at least a part of the step (II) for shaping the obtained W / O emulsion and the step (III) for polymerizing the shaped W / O emulsion may be performed simultaneously.

<< B-1. Step for preparing W / O type emulsion (I) >>
The W / O type emulsion that can be used to obtain the foamed diffuse reflector of the present invention is a W / O type emulsion containing a continuous oil phase component and an aqueous phase component immiscible with the continuous oil phase component. More specifically, the W / O type emulsion is obtained by dispersing an aqueous phase component in a continuous oil phase component.

The ratio of the water phase component to the continuous oil phase component in the W / O type emulsion that can be used to obtain the foamed diffuse reflector of the present invention is any suitable ratio within a range in which the W / O type emulsion can be formed. It can be taken. The ratio of the water phase component and the continuous oil phase component in the W / O type emulsion that can be used to obtain the foamed diffuse reflector of the present invention is the structural ratio of the foam obtained by polymerization of the W / O type emulsion. It can be an important factor in determining mechanical and performance characteristics. Specifically, the ratio of the water phase component to the continuous oil phase component in the W / O emulsion that can be used to obtain the foamed diffuse reflector of the present invention is the foam obtained by polymerization of the W / O emulsion. It can be an important factor in determining the body density, bubble size, bubble structure, and dimensions of the wall forming the porous structure.

The ratio of the aqueous phase component in the W / O emulsion that can be used to obtain the foamed diffuse reflector of the present invention is preferably 30% by weight, more preferably 40% by weight, and still more preferably as the lower limit. Is 50% by weight, particularly preferably 55% by weight, and the upper limit is preferably 95% by weight, more preferably 90% by weight, still more preferably 85% by weight, and particularly preferably 80% by weight. % By weight. If the ratio of the aqueous phase component in the W / O emulsion that can be used to obtain the foamed diffuse reflector of the present invention is within the above range, the effects of the present invention can be sufficiently exhibited.

The W / O emulsion that can be used to obtain the foamed diffuse reflector of the present invention may contain any appropriate additive as long as the effects of the present invention are not impaired. Examples of such additives include tackifying resins; talc; calcium carbonate, magnesium carbonate, silicic acid and salts thereof, clay, mica powder, aluminum hydroxide, magnesium hydroxide, zinc white, bentonine, carbon black, Examples thereof include fillers such as silica, alumina, aluminum silicate, acetylene black, and aluminum powder; pigments; dyes; Only one kind of such an additive may be contained, or two or more kinds thereof may be contained.

Any appropriate method can be adopted as a method for producing a W / O type emulsion that can be used for obtaining the foamed diffuse reflector of the present invention. As a method for producing a W / O type emulsion that can be used for obtaining the foamed diffuse reflector of the present invention, for example, a continuous oil phase component and an aqueous phase component are continuously supplied to an emulsifier to obtain a W / O type. A W / O type emulsion can be obtained by adding an appropriate amount of aqueous phase component to the continuous oil phase component in an emulsion machine and supplying the aqueous phase component continuously with stirring. Examples include “batch method” to be formed.

When producing a W / O type emulsion that can be used to obtain the foamed diffuse reflector of the present invention, as a shearing means for obtaining an emulsion state, for example, a rotor stator mixer, a homogenizer, a microfluidizer or the like was used. Application of high shear conditions. In addition, as another shearing means for obtaining an emulsion state, for example, gentle mixing of continuous and dispersed phases by application of low shear conditions using a moving blade mixer or a pin mixer, low stirring conditions using a magnetic stir bar, etc. Can be mentioned.

Examples of the apparatus for preparing the W / O emulsion by the “continuous method” include a static mixer, a rotor stator mixer, and a pin mixer. More intense agitation may be achieved by increasing the agitation speed or by using an apparatus designed to finely disperse the aqueous phase component in the W / O emulsion by a mixing method.

Examples of the apparatus for preparing the W / O emulsion by the “batch method” include manual mixing and shaking, a driven blade mixer, and a three-propeller mixing blade. Specifically, “TK Ajihomomica (trade name)” and “TK Combimix (trade name)” manufactured by Primix Co., Ltd. produce the target W / O emulsion under reduced pressure. This is possible, and the resulting W / O emulsion greatly reduces the incorporation of bubbles.

Any appropriate method can be adopted as a method for preparing the continuous oil phase component. As a method for preparing the continuous oil phase component, typically, for example, a mixed syrup containing a hydrophilic polyurethane-based polymer and an ethylenically unsaturated monomer is prepared, and subsequently, a polymerization initiator, It is preferable to prepare a continuous oil phase component by blending a crosslinking agent and any other appropriate components.

Any appropriate method can be adopted as a method for preparing the hydrophilic polyurethane-based polymer. A typical method for preparing a hydrophilic polyurethane-based polymer is, for example, by reacting polyoxyethylene polyoxypropylene glycol and a diisocyanate compound in the presence of a urethane reaction catalyst.

<B-1-1. Water phase component>
The aqueous phase component can be any aqueous fluid that is substantially immiscible with the continuous oil phase component. From the viewpoint of ease of handling and low cost, water such as ion-exchanged water is preferable.

The water phase component may contain any appropriate additive as long as the effects of the present invention are not impaired. Examples of such additives include polymerization initiators and water-soluble salts. The water-soluble salt can be an effective additive for further stabilizing the W / O emulsion. Examples of such water-soluble salts include sodium carbonate, calcium carbonate, potassium carbonate, sodium phosphate, calcium phosphate, potassium phosphate, sodium chloride, potassium chloride and the like. Only one kind of such an additive may be contained, or two or more kinds thereof may be contained. The additive that can be contained in the aqueous phase component may be only one kind or two or more kinds.

<B-1-2. Continuous oil phase component>
The continuous oil phase component preferably contains a hydrophilic polyurethane polymer and an ethylenically unsaturated monomer. The content ratio of the hydrophilic polyurethane polymer and the ethylenically unsaturated monomer in the continuous oil phase component can take any appropriate content ratio as long as the effects of the present invention are not impaired.

The hydrophilic polyurethane-based polymer depends on the polyoxyethylene ratio in the polyoxyethylene polyoxypropylene glycol unit constituting the hydrophilic polyurethane-based polymer or the amount of the aqueous phase component to be blended. The hydrophilic polyurethane polymer is in the range of 10 to 30 parts by weight with respect to 70 to 90 parts by weight of the ethylenically unsaturated monomer, and more preferably hydrophilic with respect to 75 to 90 parts by weight of the ethylenically unsaturated monomer. The polyurethane polymer is in the range of 10 to 25 parts by weight. Further, for example, the hydrophilic polyurethane polymer is preferably in the range of 1 to 30 parts by weight, more preferably 1 to 25 parts by weight of the hydrophilic polyurethane polymer with respect to 100 parts by weight of the aqueous phase component. It is a range. If the content ratio of the hydrophilic polyurethane polymer is within the above range, the effects of the present invention can be sufficiently exhibited.

(B-1-2-1. Hydrophilic polyurethane polymer)
The hydrophilic polyurethane-based polymer preferably contains a polyoxyethylene polyoxypropylene unit derived from polyoxyethylene polyoxypropylene glycol, and 5 to 25% by weight of the polyoxyethylene polyoxypropylene unit is polyoxyethylene polyoxypropylene unit. Ethylene.

As described above, the content of polyoxyethylene in the polyoxyethylene polyoxypropylene unit is preferably 5% by weight to 25% by weight, and the lower limit is more preferably 10% by weight. More preferably, it is 25% by weight, and more preferably 20% by weight. The polyoxyethylene in the polyoxyethylene polyoxypropylene unit exhibits an effect of stably dispersing the aqueous phase component in the continuous oil phase component. When the content of polyoxyethylene in the polyoxyethylene polyoxypropylene unit is less than 5% by weight, it may be difficult to stably disperse the water phase component in the continuous oil phase component. If the polyoxyethylene content in the polyoxyethylene polyoxypropylene unit exceeds 25% by weight, there is a risk of phase inversion from a W / O type emulsion to an O / W type (oil-in-water type) emulsion as it approaches the HIPE condition. There is.

A conventional hydrophilic polyurethane polymer can be obtained by reacting a diisocyanate compound with a hydrophobic long-chain diol, polyoxyethylene glycol and derivatives thereof, and a low molecular active hydrogen compound (chain extender). Since the number of polyoxyethylene groups contained in the hydrophilic polyurethane polymer obtained in 1) is uneven, the emulsion stability of such a W / O emulsion containing such a hydrophilic polyurethane polymer may be reduced. There is. On the other hand, the hydrophilic polyurethane-based polymer contained in the continuous oil phase component of the W / O emulsion that can be used to obtain the foamed diffuse reflector of the present invention has a characteristic structure as described above. When included in the continuous oil phase component of the / O type emulsion, excellent emulsifiability and excellent stationary storage stability can be expressed without positively adding an emulsifier or the like.

The hydrophilic polyurethane polymer is preferably obtained by reacting polyoxyethylene polyoxypropylene glycol with a diisocyanate compound. In this case, the ratio between the polyoxyethylene polyoxypropylene glycol and the diisocyanate compound is NCO / OH (equivalent ratio), and the lower limit is preferably 1, more preferably 1.2, and still more preferably 1. .4, particularly preferably 1.6, and the upper limit is preferably 3, more preferably 2.5, and even more preferably 2. When NCO / OH (equivalent ratio) is less than 1, a gelled product may be easily formed when a hydrophilic polyurethane polymer is produced. When NCO / OH (equivalent ratio) exceeds 3, the residual diisocyanate compound increases, and the W / O emulsion that can be used to obtain the foamed diffuse reflector of the present invention may become unstable.

As polyoxyethylene polyoxypropylene glycol, for example, polyether polyol (ADEKA (registered trademark) Pluronic L-31, L-61, L-71, L-101, L-121, L-42 manufactured by ADEKA Corporation) , L-62, L-72, L-122, 25R-1, 25R-2, 17R-2) and polyoxyethylene polyoxypropylene glycol (Pronon (registered trademark) 052, 102, 202). As for polyoxyethylene polyoxypropylene glycol, only 1 type may be used and 2 or more types may be used together.

Examples of the diisocyanate compound include aromatic, aliphatic, and alicyclic diisocyanates, dimers and trimers of these diisocyanates, polyphenylmethane polyisocyanate, and the like. Aromatic, aliphatic, and alicyclic diisocyanates include tolylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, 1,5-naphthylene diisocyanate. 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, butane-1,4-diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, cyclohexane-1,4 -Diisocyanate, dicyclohexylmethane-4,4-diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane, methyl Cyclohexane diisocyanate, m- tetramethylxylylene diisocyanate. Examples of the diisocyanate trimer include isocyanurate type, burette type, and allophanate type. Only 1 type may be used for a diisocyanate compound and it may use 2 or more types together.

The diisocyanate compound may be selected as appropriate from the viewpoint of urethane reactivity with a polyol, and the like. From the viewpoint of rapid urethane reactivity with polyol and suppression of reaction with water, it is preferable to use alicyclic diisocyanate.

The weight average molecular weight of the hydrophilic polyurethane polymer is preferably 5000 as a lower limit, more preferably 7000, still more preferably 8000, particularly preferably 10,000, and preferably 50,000 as an upper limit. More preferably, it is 40000, more preferably 30000, and particularly preferably 20000.

The hydrophilic polyurethane-based polymer may have an unsaturated double bond capable of radical polymerization at the terminal. By having an unsaturated double bond capable of radical polymerization at the terminal of the hydrophilic polyurethane-based polymer, the effects of the present invention can be further exhibited.

(B-1-2. Ethylenically unsaturated monomer)
As the ethylenically unsaturated monomer, any appropriate monomer can be adopted as long as it is a monomer having an ethylenically unsaturated double bond. Only one type of ethylenically unsaturated monomer may be used, or two or more types may be used.

The ethylenically unsaturated monomer preferably contains a (meth) acrylic acid ester. The content ratio of the (meth) acrylic acid ester in the ethylenically unsaturated monomer is preferably 80% by weight, more preferably 85% by weight as the lower limit, and preferably 100% by weight as the upper limit. More preferably, it is 98% by weight. Only one (meth) acrylic acid ester may be used, or two or more may be used.

The (meth) acrylic acid ester is preferably an alkyl (meth) acrylate having an alkyl group having 1 to 20 carbon atoms (concept including a cycloalkyl group, an alkyl (cycloalkyl) group, and a (cycloalkyl) alkyl group). It is. The number of carbon atoms of the alkyl group is preferably 4-18. In addition, (meth) acryl means acryl and / or methacryl, and (meth) acrylate means acrylate and / or methacrylate.

Examples of the alkyl (meth) acrylate having an alkyl group having 1 to 20 carbon atoms include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, and s-butyl. (Meth) acrylate, t-butyl (meth) acrylate, isobutyl (meth) acrylate, n-pentyl (meth) acrylate, isopentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, isoamyl (meth) Acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, iso Sil (meth) acrylate, n-dodecyl (meth) acrylate, isomyristyl (meth) acrylate, n-tridecyl (meth) acrylate, n-tetradecyl (meth) acrylate, stearyl (meth) acrylate, lauryl (meth) acrylate, pentadecyl (Meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate, nonadecyl (meth) acrylate, eicosyl (meth) acrylate, isostearyl (meth) acrylate, isobornyl (meth) acrylate, etc. It is done. Among these, n-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and isobornyl (meth) acrylate are preferable. The alkyl (meth) acrylate having an alkyl group having 1 to 20 carbon atoms may be only one type or two or more types.

The ethylenically unsaturated monomer preferably further contains a polar monomer copolymerizable with (meth) acrylic acid ester. By including the polar monomer, the effects of the present invention can be further exhibited. The content of the polar monomer in the ethylenically unsaturated monomer is preferably 0% by weight, more preferably 2% by weight as the lower limit, and preferably 20% by weight, more preferably as the upper limit. 15% by weight. Only one type of polar monomer may be used, or two or more types may be used.

Examples of polar monomers include (meth) acrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, ω-carboxy-polycaprolactone monoacrylate, phthalic acid monohydroxyethyl acrylate, itaconic acid, maleic acid, and fumaric acid. Carboxyl group-containing monomers such as acid and crotonic acid; acid anhydride monomers such as maleic anhydride and itaconic anhydride; 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, (meth) acrylic acid 4-hydroxybutyl, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, (4-hydroxymethyl) Hydroxyl group-containing monomers such as (rucyclohexyl) methyl (meth) acrylate; amide group-containing monomers such as N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, and hydroxyethyl (meth) acrylamide; Can be mentioned.

(B-1-2-3. Polymerization initiator)
The continuous oil phase component preferably contains a polymerization initiator.

Examples of the polymerization initiator include radical polymerization initiators and redox polymerization initiators. Examples of the radical polymerization initiator include a thermal polymerization initiator and a photopolymerization initiator.

Examples of the thermal polymerization initiator include azo compounds, peroxides, peroxycarbonic acid, peroxycarboxylic acid, potassium persulfate, t-butylperoxyisobutyrate, 2,2′-azobisisobutyronitrile and the like. .

Examples of the photopolymerization initiator include 4- (2-hydroxyethoxy) phenyl (2-hydroxy-2-propyl) ketone (for example, Ciba Japan, trade name: Darocur-2959), α-hydroxy- α, α'-dimethylacetophenone (for example, Ciba Japan, trade name: Darocur-1173), methoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone (for example, Ciba Japan, trade name) Acetophenone-based photopolymerization initiators such as Irgacure-651) and 2-hydroxy-2-cyclohexylacetophenone (for example, product name; Irgacure-184 manufactured by Ciba Japan); Ketal-based photopolymerization initiators such as benzyldimethyl ketal Agents; Other halogenated ketones; Acylphosphine oxa (As an example, Ciba Japan Co., Ltd., trade name: Irgacure -819); de and the like.

The polymerization initiator may contain only 1 type, and may contain 2 or more types.

The content of the polymerization initiator is preferably 0.05% by weight, more preferably 0.1% by weight, more preferably 0.1%, and preferably 5.0% as a lower limit with respect to the entire continuous oil phase component. % By weight, more preferably 1.0% by weight. When the content of the polymerization initiator is less than 0.05% by weight based on the entire continuous oil phase component, the amount of unreacted monomer components increases, and the amount of residual monomer in the resulting foamed diffuse reflector may increase. There is. When the content of the polymerization initiator exceeds 5.0% by weight with respect to the entire continuous oil phase component, the mechanical properties of the obtained foamed diffuse reflector may be lowered.

Note that the amount of radicals generated by the photopolymerization initiator also varies depending on the type and intensity of irradiated light, the irradiation time, the amount of dissolved oxygen in the monomer and solvent mixture, and the like. And when there is much dissolved oxygen, the radical generation amount by a photoinitiator is suppressed, superposition | polymerization does not fully advance and an unreacted substance may increase. Therefore, it is preferable that an inert gas such as nitrogen is blown into the reaction system before the light irradiation, and oxygen is replaced with an inert gas or deaerated by a reduced pressure treatment.

(B-1-2-4. Crosslinking agent)
The continuous oil phase component preferably includes a cross-linking agent.

The cross-linking agent is typically used for linking polymer chains to build a more three-dimensional molecular structure. The selection of the type and content of the cross-linking agent depends on the structural, mechanical and fluid treatment characteristics desired for the resulting foam diffuse reflector. Selection of the specific type and content of the cross-linking agent is important in achieving a desirable combination of structural properties, mechanical properties, and fluid treatment properties of the foamed diffuse reflector.

In producing the foamed diffuse reflector of the present invention, preferably, at least two types of crosslinking agents having different weight average molecular weights are used as the crosslinking agent.

In producing the foamed diffuse reflector of the present invention, more preferably, as a crosslinking agent, "from a polyfunctional (meth) acrylate having a weight average molecular weight of 800 or more, a polyfunctional (meth) acrylamide, and a polymerization reactive oligomer. “One or more selected” and “one or more selected from polyfunctional (meth) acrylate and polyfunctional (meth) acrylamide having a weight average molecular weight of 500 or less” are used in combination. Here, the polyfunctional (meth) acrylate is specifically a polyfunctional (meth) acrylate having at least two ethylenically unsaturated groups in one molecule, and the polyfunctional (meth) acrylamide is Specifically, it is polyfunctional (meth) acrylamide having at least two ethylenically unsaturated groups in one molecule.

Examples of polyfunctional (meth) acrylates include diacrylates, triacrylates, tetraacrylates, dimethacrylates, trimethacrylates, and tetramethacrylates.

Examples of the polyfunctional (meth) acrylamide include diacrylamides, triacrylamides, tetraacrylamides, dimethacrylamides, trimethacrylamides, tetramethacrylamides and the like.

The polyfunctional (meth) acrylate can be derived from, for example, diols, triols, tetraols, bisphenol A and the like. Specifically, for example, 1,10-decanediol, 1,8-octanediol, 1,6 hexanediol, 1,4-butanediol, 1,3-butanediol, 1,4 butane-2-enediol , Ethylene glycol, diethylene glycol, trimethylolpropane, pentaerythritol, hydroquinone, catechol, resorcinol, triethylene glycol, polyethylene glycol, sorbitol, polypropylene glycol, polytetramethylene glycol, bisphenol A propylene oxide modified product, and the like.

Polyfunctional (meth) acrylamide can be derived from, for example, corresponding diamines, triamines, tetraamines and the like.

Examples of the polymerization-reactive oligomer include urethane (meth) acrylate, epoxy (meth) acrylate, copolyester (meth) acrylate, and oligomer di (meth) acrylate. Preferably, it is hydrophobic urethane (meth) acrylate.

The weight average molecular weight of the polymerization-reactive oligomer is preferably 1500 or more, more preferably 2000 or more. Although the upper limit of the weight average molecular weight of a polymerization reactive oligomer is not specifically limited, For example, Preferably it is 10,000 or less.

As the cross-linking agent, “one or more selected from polyfunctional (meth) acrylates having a weight average molecular weight of 800 or more, polyfunctional (meth) acrylamides, and polymerization reactive oligomers” and “a weight average molecular weight of 500 or less. When using together with “one or more selected from functional (meth) acrylate and polyfunctional (meth) acrylamide” ”,“ polyfunctional (meth) acrylate having a weight average molecular weight of 800 or more, polyfunctional (meth) acrylamide, and polymerization ” The amount of “one or more selected from reactive oligomers” is preferably 40% by weight as a lower limit with respect to the total amount of the hydrophilic polyurethane polymer and the ethylenically unsaturated monomer in the continuous oil phase component. The upper limit is preferably 100% by weight, and more preferably 80% by weight. The amount of use of “one or more selected from a polyfunctional (meth) acrylate having a weight average molecular weight of 800 or more, a polyfunctional (meth) acrylamide, and a polymerization reactive oligomer” is a hydrophilic polyurethane-based heavy in the continuous oil phase component When the amount is less than 40% by weight based on the total amount of the coalesced monomer and the ethylenically unsaturated monomer, the cohesive force of the resulting foamed diffuse reflector may be lowered, and it may be difficult to achieve both toughness and flexibility. There is. The amount of use of “one or more selected from a polyfunctional (meth) acrylate having a weight average molecular weight of 800 or more, a polyfunctional (meth) acrylamide, and a polymerization reactive oligomer” is a hydrophilic polyurethane-based heavy in the continuous oil phase component When it exceeds 100 weight% with respect to the total amount of a coalescence and an ethylenically unsaturated monomer, the emulsion stability of a W / O type emulsion will fall and there exists a possibility that a desired foaming diffused reflection body may not be obtained.

As the cross-linking agent, “one or more selected from polyfunctional (meth) acrylates having a weight average molecular weight of 800 or more, polyfunctional (meth) acrylamides, and polymerization reactive oligomers” and “a weight average molecular weight of 500 or less. When using together with “one or more selected from functional (meth) acrylate and polyfunctional (meth) acrylamide” ”,“ selected from polyfunctional (meth) acrylate and polyfunctional (meth) acrylamide having a weight average molecular weight of 500 or less ” The amount of “one or more” used is preferably 1% by weight, more preferably 5% as a lower limit with respect to the total amount of the hydrophilic polyurethane polymer and the ethylenically unsaturated monomer in the continuous oil phase component. The upper limit is preferably 30% by weight, and more preferably 20% by weight. Use amount of “one or more selected from polyfunctional (meth) acrylate having a weight average molecular weight of 500 or less and polyfunctional (meth) acrylamide” is a hydrophilic polyurethane polymer and ethylenic unsaturated in a continuous oil phase component When the amount is less than 1% by weight based on the total amount of monomers, the heat resistance is lowered, and the cell structure may be crushed by contraction in the step (IV) of dehydrating the water-containing polymer. Use amount of “one or more selected from polyfunctional (meth) acrylate having a weight average molecular weight of 500 or less and polyfunctional (meth) acrylamide” is a hydrophilic polyurethane polymer and ethylenic unsaturated in a continuous oil phase component When it exceeds 30% by weight with respect to the total amount of the monomers, the toughness of the foamed diffuse reflector to be obtained is lowered, and there is a possibility that brittleness is exhibited.

The crosslinking agent may contain only 1 type and may contain 2 or more types.

(B-1-2-5. Other components in the continuous oil phase component)
The continuous oil phase component may contain any appropriate other component as long as the effects of the present invention are not impaired. Examples of such other components typically include a catalyst, an antioxidant, a light stabilizer, and an organic solvent. Such other components may be only one type or two or more types.

Examples of the catalyst include a urethane reaction catalyst. Any appropriate catalyst can be adopted as the urethane reaction catalyst. Specific examples include dibutyltin dilaurate.

As the catalyst content ratio, any appropriate content ratio can be adopted depending on the target catalytic reaction.

The catalyst may contain only one type or two or more types.

Examples of the antioxidant include phenolic antioxidants, thioether antioxidants, and phosphorus antioxidants.

As the content ratio of the antioxidant, any appropriate content ratio can be adopted as long as the effects of the present invention are not impaired.

An antioxidant may contain only 1 type and may contain 2 or more types.

As the organic solvent, any appropriate organic solvent can be adopted as long as the effects of the present invention are not impaired.

Any appropriate content ratio can be adopted as the content ratio of the organic solvent as long as the effects of the present invention are not impaired.

The organic solvent may contain only 1 type, and may contain 2 or more types.

As the light stabilizer, any appropriate light stabilizer can be adopted as long as the effects of the present invention are not impaired.

Any appropriate content ratio can be adopted as the content ratio of the light stabilizer as long as the effects of the present invention are not impaired.

The light stabilizer may contain only 1 type, and may contain 2 or more types.

<< B-2. Step of shaping W / O type emulsion (II) >>
In the step (II), any appropriate shaping method can be adopted as a method for shaping the W / O emulsion. For example, there is a method in which a W / O emulsion is continuously supplied onto a traveling belt and shaped into a smooth sheet on the belt. Moreover, the method of apply | coating to one surface of a thermoplastic resin film, and shaping is mentioned.

In the step (II), as a method of shaping the W / O type emulsion, when adopting a method of coating and shaping on one surface of a thermoplastic resin film, as a method of coating, for example, a roll coater, Examples include a method using a die coater, a knife coater, or the like.

<< B-3. Step of polymerizing shaped W / O emulsion (III) >>
In the step (III), any appropriate polymerization method can be adopted as a method for polymerizing the shaped W / O emulsion. For example, the belt surface of a belt conveyor is heated by a heating device, and a W / O type emulsion is continuously supplied onto a traveling belt and shaped into a smooth sheet on the belt by heating. A W / O emulsion is continuously supplied onto the running belt, with a method of polymerization and a structure in which the belt surface of the belt conveyor is heated by irradiation of active energy rays, and a smooth sheet is formed on the belt. The method of superposing | polymerizing by irradiation of an active energy ray is mentioned, shaping.

In the case of polymerization by heating, the polymerization temperature (heating temperature) is preferably 23 ° C., more preferably 50 ° C., still more preferably 70 ° C., particularly preferably 80 ° C. as the lower limit. The upper limit is preferably 90 ° C, and is preferably 150 ° C, more preferably 130 ° C, and even more preferably 110 ° C. When the polymerization temperature is less than 23 ° C., the polymerization takes a long time, and industrial productivity may be reduced. When the polymerization temperature exceeds 150 ° C., the pore diameter of the foamed diffuse reflector obtained may be non-uniform or the strength of the foamed diffuse reflector may be reduced. The polymerization temperature need not be constant. For example, the polymerization temperature may be varied in two stages or multiple stages during the polymerization.

In the case of polymerization by irradiation with active energy rays, examples of the active energy rays include ultraviolet rays, visible rays, and electron beams. The active energy rays are preferably ultraviolet rays and visible rays, and more preferably visible to ultraviolet rays having a wavelength of 200 nm to 800 nm. Since the W / O type emulsion has a strong tendency to scatter light, it is possible to penetrate the W / O type emulsion by using visible to ultraviolet light having a wavelength of 200 nm to 800 nm. In addition, a photopolymerization initiator that can be activated at a wavelength of 200 nm to 800 nm is easily available and a light source is easily available.

The wavelength of the active energy ray is preferably 200 nm as a lower limit, more preferably 300 nm, and preferably 800 nm, more preferably 450 nm as an upper limit.

As a typical apparatus used for irradiation of active energy rays, for example, an ultraviolet lamp capable of performing ultraviolet irradiation includes an apparatus having a spectral distribution in a wavelength region of 300 nm to 400 nm. , Black light (trade name manufactured by Toshiba Lighting & Technology Co., Ltd.), metal halide lamp and the like.

The illuminance at the time of irradiation with active energy rays can be set to any appropriate illuminance by adjusting the distance from the irradiation device to the irradiated object and the voltage. For example, by the method disclosed in Japanese Patent Application Laid-Open No. 2003-13015, ultraviolet irradiation in each step is performed in a plurality of stages, and thereby the adhesive performance can be precisely adjusted.

In order to prevent the adverse effect of oxygen having an inhibitory action on the ultraviolet rays, for example, a W / O emulsion is applied to one surface of a substrate such as a thermoplastic resin film and then shaped under an inert gas atmosphere. UV rays such as polyethylene terephthalate coated with a release agent such as silicone after passing through a W / O emulsion on one surface of a substrate such as a thermoplastic resin film and shaping, but blocking oxygen It is preferable to carry out by covering the film.

As the thermoplastic resin film, any appropriate thermoplastic resin film can be adopted as long as it can be formed by coating a W / O emulsion on one surface. Examples of the thermoplastic resin film include plastic films and sheets such as polyester, olefin resin, and polyvinyl chloride. Further, the film may be subjected to a peeling treatment on one side or both sides thereof.

The inert gas atmosphere is an atmosphere in which oxygen in the light irradiation zone is replaced with an inert gas. Therefore, in the inert gas atmosphere, it is necessary that oxygen is not present as much as possible, and the oxygen concentration is preferably 5000 ppm or less.

<< B-4. Step of dehydrating the obtained water-containing polymer (IV) >>
In step (IV), the obtained water-containing polymer is dehydrated. In the water-containing polymer obtained in step (III), the aqueous phase component is present in a dispersed state. By removing the aqueous phase component by dehydration and drying, a foam contained in the foamed diffuse reflector of the present invention is obtained. The obtained foam can be directly used as the foamed diffuse reflector of the present invention. Further, as described later, by combining with a base material, the foamed diffuse reflector of the present invention can be obtained. Moreover, the foaming diffused reflection body in which the foaming diffused reflection body of this invention has the hole (through-hole) which penetrates in said thickness direction can be obtained by perforating a foaming diffused reflection body by the well-known counterbore processing method, for example. it can.

Any appropriate drying method can be adopted as the dehydration method in step (IV). Examples of such a drying method include vacuum drying, freeze drying, press drying, microwave drying, drying in a heat oven, drying with infrared rays, or a combination of these techniques.

<< B-5. When the foamed diffuse reflector of the present invention contains a base material >>
When the foamed diffuse reflector of the present invention contains a substrate, as one preferred embodiment of the method for producing the foamed diffuse reflector of the present invention, a W / O emulsion is applied to one surface of the substrate, W / O emulsion is polymerized by heating or irradiation with active energy rays in an active gas atmosphere or in a state where oxygen is blocked by coating with a UV transparent film coated with a release agent such as silicone. Examples of the water-containing polymer include dehydrating the obtained water-containing polymer to form a foamed diffuse reflector having a substrate / foamed layer laminate structure.

As another preferred embodiment of the method for producing a foamed diffuse reflector of the present invention, two sheets of W / O type emulsions coated on one surface of an ultraviolet transmissive film coated with a release agent such as silicone are prepared. Then, a base material is laminated on the application surface of one of the two W / O emulsion application sheets, and another W / O emulsion application sheet is provided on the other surface of the laminated base material. In a state where the coating surfaces are laminated so as to match, the W / O emulsion is polymerized by heating or irradiation with active energy rays to form a water-containing polymer, and the resulting water-containing polymer is dehydrated to produce foam. The form made into the foaming diffused reflection body which has the laminated structure of a layer / base material / foaming layer is mentioned.

Examples of the method of applying the W / O type emulsion to one side of the base material or one surface of the ultraviolet ray transmissive film coated with a release agent such as silicone include a roll coater, a die coater, and a knife coater.

Hereinafter, the present invention will be described based on examples, but the present invention is not limited thereto. The normal temperature means 23 ° C.

(Molecular weight measurement)
The weight average molecular weight was determined by GPC (gel permeation chromatography).
Equipment: “HLC-8020” manufactured by Tosoh Corporation
Column: “TSKgel GMH _HR- H (20)” manufactured by Tosoh Corporation
Solvent: Tetrahydrofuran Standard: Polystyrene

(Measurement of average pore diameter)
The obtained foam was cut in the thickness direction with a microtome cutter as a measurement sample. The cut surface of the measurement sample was photographed with a scanning electron microscope (Hitachi, S-3400N) at 800 to 5000 times. Using the photographed image, measure the pore diameter of an arbitrary range of spherical bubbles, the diameter of a through-hole penetrating between the spherical bubbles of an arbitrary range, and the pore diameter of the surface opening of an arbitrary range. The average hole diameter, the average hole diameter of the through holes, and the average hole diameter of the surface openings were calculated.

(Measurement of bubble rate)
Only the oil phase component at the time of producing the emulsion was polymerized, and the obtained polymer sheet was cut into five pieces of 100 mm × 100 mm to obtain test pieces, and the apparent density was obtained by dividing the weight by the volume. The average value of the apparent density obtained was taken as the density of the resin component constituting the foamed layer. The cell ratio of the foam layer was calculated by the following formula using the relative density obtained by dividing the density of the foam layer by the density of the resin component.
Bubble ratio = (1−relative density) × 100

(Diffuse reflectance, transmittance)
Using a spectrophotometer UV-2250 manufactured by Shimadzu Corporation equipped with an integrating sphere device, the diffuse reflectance and transmittance in the wavelength region of 220 nm to 800 nm were measured every 1 nm. Measurement incident light was incident on the foam at an incident angle of 0 °, and the reflectance at this time was defined as diffuse reflectance. At this time, the measuring apparatus was adjusted with the reflectance of the barium sulfate powder as 100%.

(Light resistance test)
Using a die plastic metal weather KU-R5N-W (manufactured by Daipura Wintes Co., Ltd.), ultraviolet rays with an illuminance of 90 mW / cm ² were continuously irradiated for 100 hours with a metal halide lamp under the conditions of a temperature of 63 ° C. and a humidity of 50%.

(Dimensional change rate when stored at 125 ° C for 22 hours)
The heating dimensional change of the obtained foamed diffuse reflector was measured in accordance with JIS-K-6767 dimensional stability evaluation at high temperature. That is, the obtained foamed diffuse reflector was cut into a size of 100 mm × 100 mm to form a test piece, stored in an oven at 125 ° C. for 22 hours, and then conformed to the dimensional stability evaluation at high temperature of JIS-K-6767. Then, the rate of change in dimensions before and after the heat storage treatment was determined.

(Measurement of 100 ° C holding power)
The obtained foamed diffuse reflector (3) was lined with a polyester adhesive tape (Nitto Denko No. 31B 80 μm). The obtained foam diffuse reflector (2) and the foam diffuse reflector (3) lined with polyester adhesive tape are cut to 10 mm x 100 mm, one separator is peeled off, and the foam surface is attached to the bake plate at 10 mm x 20 mm. Affixing was performed so as to have an attachment area, and a 2 kg roller was reciprocated once to perform pressure bonding. After the pressure bonding, a bake plate was fixed so that the sample was vertical in an atmosphere of 100 ° C., and a load of 500 g was applied to one of the foams and left for 2 hours. After leaving, the amount of deviation of the sample application position after 2 hours was measured.

[Production Example 1]: Preparation of mixed syrup 1 In a reaction vessel equipped with a cooling tube, a thermometer, and a stirrer, isobornyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., hereinafter "IBXA") was used as an ethylenically unsaturated monomer. 173.2 parts by weight, 100 parts by weight of Adeka (registered trademark) Pluronic L-62 (molecular weight 2500, polyether polyol manufactured by ADEKA Corporation) as polyoxyethylene polyoxypropylene glycol, and urethane reaction catalyst Dibutyltin dilaurate (manufactured by Kishida Chemical Co., Ltd., hereinafter abbreviated as “DBTL”) is added in an amount of 0.014 part by weight and stirred, while hydrogenated xylylene diisocyanate (Takeda Pharmaceutical Co., Ltd., Takenate 600, below). 12.4 parts by weight of the solution was added dropwise and reacted at 65 ° C. for 4 hours. In addition, the usage-amount of the polyisocyanate component and the polyol component was NCO / OH (equivalent ratio) = 1.6. Thereafter, 5.6 parts by weight of 2-hydroxyethyl acrylate (manufactured by Kishida Chemical Co., Ltd., hereinafter abbreviated as “HEA”) was added dropwise and reacted at 65 ° C. for 2 hours to mix a hydrophilic polyurethane polymer / ethylenically unsaturated monomer. A syrup was obtained. The weight average molecular weight of the obtained hydrophilic polyurethane polymer was 15,000. 24.7 parts by weight of 2-ethylhexyl acrylate (manufactured by Toa Gosei Co., Ltd., hereinafter abbreviated as “2EHA”) per 100 parts by weight of the obtained hydrophilic polyurethane polymer / ethylenically unsaturated monomer mixed syrup, IBXA 69.3 parts by weight, 10.5 parts by weight of acrylic acid (manufactured by Toa Gosei Co., Ltd., hereinafter abbreviated as “AA”) as a polar monomer, and a hydrophilic polyurethane polymer / ethylenically unsaturated monomer mixed syrup 1 It was.

[Production Example 2]: Preparation of mixed syrup 2 In a reaction vessel equipped with a condenser, a thermometer, and a stirrer, 173.2 parts by weight of 2EHA as an ethylenically unsaturated monomer, and ADEKA (polyoxyethylene polyoxypropylene glycol) (Registered trademark) Pluronic L-62 (molecular weight 2500, ADEKA, polyether polyol) 100 parts by weight and 0.014 parts by weight of DBTL as a urethane reaction catalyst were added, and 12.4 parts by weight of HXDI was added dropwise while stirring. , Reacted at 65 ° C. for 4 hours. In addition, the usage-amount of the polyisocyanate component and the polyol component was NCO / OH (equivalent ratio) = 1.6. Thereafter, 5.6 parts by weight of HEA was added dropwise and reacted at 65 ° C. for 2 hours to obtain a hydrophilic polyurethane polymer / ethylenically unsaturated monomer mixed syrup having acryloyl groups at both ends. The weight average molecular weight of the obtained hydrophilic polyurethane polymer having acryloyl groups at both ends was 15,000. 27.3 parts by weight of 2EHA, n-butyl acrylate (manufactured by Toa Gosei Co., Ltd., hereinafter “100 parts by weight of a hydrophilic polyurethane polymer having an acryloyl group at both ends / ethylenically unsaturated monomer mixed syrup”) 51.8 parts by weight, 17.6 parts by weight of IBXA, and 10.5 parts by weight of AA as a polar monomer were added to obtain a hydrophilic polyurethane polymer / ethylenically unsaturated monomer mixed syrup 2.

[Example 1]
To 100 parts by weight of the hydrophilic polyurethane-based polymer / ethylenically unsaturated monomer mixed syrup 1 obtained in Production Example 1, 15.9 parts by weight of 1,6-hexanediol diacrylate, and as a reactive oligomer, polytetra Polyurethane synthesized from methylene glycol (hereinafter abbreviated as “PTMG”) and isophorone diisocyanate (hereinafter abbreviated as “IPDI”), both ends of which are treated with HEA, urethane acrylate having ethylenically unsaturated groups at both ends (Hereinafter abbreviated as “UA”) (molecular weight 3720) 47.7 parts by weight, diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide (manufactured by BASF, trade name “Lucirin TPO”) 0.48 parts by weight Part, hindered phenolic antioxidant (Ciba Japan, trade name “Irganox” 010 ") 0.95 parts by weight of a light stabilizer (BASF Corp., trade name; TINUVIN123) 2 parts by weight were uniformly mixed, continuous oil phase component (hereinafter, was referred to as) an" oil phase ". On the other hand, 300 parts by weight of ion-exchanged water as an aqueous phase component (hereinafter referred to as “aqueous phase”) with respect to 100 parts by weight of the oil phase is continuously introduced into a stirring mixer that is an emulsifier charged with the oil phase at room temperature. Were added dropwise to prepare a stable W / O emulsion. The weight ratio of the water phase to the oil phase was 75/25.
The obtained W / O emulsion was stored at room temperature for 1 hour, and then applied onto a substrate that had been subjected to a release treatment so that the thickness after light irradiation was 0.5 mm, and was continuously molded. Further, a 38 μm-thick polyethylene terephthalate (PET) film subjected to a release treatment was placed thereon. This sheet was irradiated with ultraviolet light having a light illuminance of 5 mW / cm ² (measured with Topcon UVR-T1 having a peak sensitivity maximum wavelength of 350 nm) using black light (15 W / cm), and a highly water-containing crosslinked polymer having a thickness of 0.5 mm was obtained. Obtained. Next, the top film was peeled off, and the high water content crosslinked polymer was heated at 130 ° C. for 20 minutes to obtain a foamed diffuse reflector (1) containing a foam having a thickness of 0.5 mm.
The obtained foaming diffused reflection body (1) was used for the said evaluation. The results are shown in Table 1.
Moreover, the photograph figure of the surface / cross-section SEM photograph which image | photographed the obtained foaming diffused reflection body (1) from diagonally was shown in FIG.

[Example 2]
The W / O emulsion prepared in Example 1 is 0.135 mm in thickness after light irradiation on the PET surface side of an aluminum-deposited PET substrate (manufactured by Toray Film Processing Co., Ltd., Metal Me 25S). A foamed diffuse reflector having a total thickness of 0.16 mm (foam thickness: 0.135 mm, PET base material (light-shielding layer) thickness: 0.025 mm) by the same operation as in Example 1 except that the coating was performed as described above. (2) was obtained.
The obtained foaming diffused reflection body (2) was used for the said evaluation. The results are shown in Table 1.

Example 3
To 100 parts by weight of the hydrophilic polyurethane polymer / ethylenically unsaturated monomer mixed syrup 1 obtained in Production Example 2, 1,6-hexanediol diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., trade name “NK Ester A” -HD-N ") (molecular weight 226) 11.9 parts by weight, as a reactive oligomer, both ends of polyurethane synthesized from PTMG and IPDI were treated with HEA, UA having ethylenically unsaturated groups at both ends 47.7 parts by weight (molecular weight 3720), 0.48 parts by weight of diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide (manufactured by BASF, trade name “Lucirin TPO”) as a photoinitiator, hindered 0.95 parts by weight of a phenolic antioxidant (Ciba Japan, trade name “Irganox 1010”), light stabilizer (as an example Manufactured by BASF, trade name; TINUVIN123) 2 parts by weight were uniformly mixed, continuous oil phase component (hereinafter, was referred to as) an "oil phase". On the other hand, 300 parts by weight of ion-exchanged water as an aqueous phase component (hereinafter referred to as “aqueous phase”) with respect to 100 parts by weight of the oil phase is continuously introduced into a stirring mixer that is an emulsifier charged with the oil phase at room temperature. Were added dropwise to prepare a stable W / O emulsion. The weight ratio of the water phase to the oil phase was 75/25.
The W / O emulsion, which was stored at room temperature for 30 minutes from the preparation, was applied on the release-treated polyethylene terephthalate film with a thickness of 38 μm so that the thickness of the foamed layer after light irradiation was 150 μm. The sheet was continuously formed into a sheet shape. Furthermore, a 50 μm thick polyester fiber laminated fabric (trade name “MILIFE (registered trademark) TY0503FE” manufactured by JX Nippon Mining & Chemicals, Inc., Inc.), in which stretched polyester long fibers are aligned and stacked vertically, was laminated. . Further, separately from the preparation, the W / O type emulsion, which was stored at room temperature for 30 minutes, was placed on a PET film having a thickness of 38 μm, and the foamed layer after light irradiation had a thickness of 150 μm. A coated material was prepared, and the coated surface was covered with the polyester fiber laminated fabric. This sheet was irradiated with ultraviolet light having a light illuminance of 5 mW / cm ² (measured with Topcon UVR-T1 having a peak sensitivity maximum wavelength of 350 nm) using black light (15 W / cm) to obtain a highly hydrous crosslinked polymer having a thickness of 310 μm. . Next, the top film was peeled off, and the high water content crosslinked polymer was heated at 130 ° C. for 10 minutes, so that the total thickness was about 0.31 mm (foam thickness: 0.13 mm × 2, intermediate group). A foamed diffuse reflector (3) having a thickness of the material of 0.05 mm was obtained.
The obtained foaming diffused reflection body (3) was used for the said evaluation. The results are shown in Table 1.

In Table 1, there is an example in which the diffuse reflectance exceeds 100%, which is presumed to be caused by adjusting the measuring apparatus with the diffuse reflectance of the barium sulfate powder being 100%. The However, an example in which the measurement result of the diffuse reflectance when the barium sulfate powder that theoretically exhibits 100% diffuse reflectance is used as a comparative material exceeds 100% is equivalent to or higher than that of the barium sulfate powder. It is thought that it shows.

The foamed diffuse reflector of the present invention is useful as a diffuse reflector provided in lighting fixtures such as LED substrates, backlight devices of liquid crystal display devices, fluorescent lamps, incandescent lamps, and natural light daylight duct devices.

100 Foam Diffuse Reflector 10 Foam 10a Foam 10b Foam 20 Base Material 30 Release Film

Claims

Comprising a foam having an open cell structure with through-holes between adjacent spherical cells;
The foam comprises a hydrophilic polyurethane polymer;
The average pore size of the spherical bubbles is less than 20 μm,
The average pore diameter of the through holes is 5 μm or less,
The surface of the foam has a surface opening having an average pore diameter of 20 μm or less,
The diffuse reflectance in the wavelength region of 400 nm to 600 nm is 90% or more.
Foam diffuse reflector.
The foaming diffused reflection body of Claim 1 whose thickness is 0.1 mm or more.
The foaming diffused reflector of Claim 1 or 2 whose dimensional change rate when preserve | saved at 125 degreeC for 22 hours is less than +/- 5%.
The foaming diffused reflection body in any one of Claim 1 to 3 whose fall of the reflectance in wavelength 550nm before and behind irradiating the ultraviolet-ray with an illuminance of 90 mW / cm < 2 > for 100 hours is less than 10%.
The foamed diffuse reflector according to any one of claims 1 to 4, further comprising a light-shielding layer on a surface opposite to the reflective surface of the foamed diffuse reflector.
The foamed diffuse reflector according to any one of claims 1 to 5, which has a hole penetrating in the thickness direction of the foamed diffuse reflector, and a diameter of the hole penetrating in the thickness direction is 20 mm to 60 mm.
A method for producing a foamed diffuse reflector comprising a foam having an open-cell structure having a through-hole between adjacent spherical cells,
Step (I) for preparing a continuous oil phase component and a W / O emulsion containing an aqueous phase component immiscible with the continuous oil phase component, and a step (II) for shaping the obtained W / O emulsion And a step (III) of polymerizing the shaped W / O emulsion, and a step (IV) of dehydrating the obtained water-containing polymer,
The continuous oil phase component includes a hydrophilic polyurethane polymer, an ethylenically unsaturated monomer, and a crosslinking agent.
Method for producing foamed diffuse reflector.
The cross-linking agent is one or more selected from polyfunctional (meth) acrylates having a weight average molecular weight of 800 or more, polyfunctional (meth) acrylamides, and polymerization reactive oligomers, and polyfunctional having a weight average molecular weight of 500 or less. The manufacturing method of the foaming diffused reflection body of Claim 7 containing 1 or more types chosen from (meth) acrylate and polyfunctional (meth) acrylamide.
A foamed diffuse reflector obtained by the production method according to claim 7 or 8.