JP2014029432A - Flexible light guide plate and method for manufacturing flexible light guide plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flexible light guide plate that maintains a small color difference between incident light color and emission light color over a long period of time from an initial time, is excellent in light source color reproducibility, emits light uniformly and effectively, can be used while being bent in any forms due to a good flexibility, and, in addition, that is excellent in UV light resistance.SOLUTION: The flexible light guide plate includes: a polyol component; a polyisocyanate component; and thermosetting polyurethane obtained by thermally setting a curing agent in the presence of a non-amine-based catalyst. The polyol component is polycarbonate polyol. The isocyanate component is aliphatic polyisocyanate. The thermosetting polyurethane has transmittance of 80%/3 mm or more of light of wavelength 375 nm measured after UV radiation.

Description

The present invention relates to a flexible light guide plate, particularly a flexible light guide plate suitable for using UV-LED light as a light source, and a method for manufacturing the same.

Conventionally, a light guide plate made of a hard and highly transparent resin material such as polymethyl methacrylate (PMMA) or polycarbonate introduces light from the side or back thereof by a fluorescent lamp, a cold cathode tube, an LED, etc. As a planar light source that emits light, it has been used in liquid crystal displays such as televisions, personal computers, and mobile phones, as well as lighting and electric signs.
However, since the light guide plate made of these transparent resin materials is poor in flexibility, when it is used for a curved display, or when it is used for lighting, signboard, etc. having a design such as an arc shape or a wave shape. In order to obtain such a molded product in advance, it is necessary to prepare a mold for each molded product, and there is a problem that the versatility is low and the manufacturing cost increases. there were. It is also possible to reduce the thickness of the light guide plate made of PMMA or polycarbonate to give flexibility, but in this case, it becomes difficult to efficiently guide light from the light source into the light guide plate. However, there are problems such as a reduction in the efficiency of introducing the light guide plate and the light guide plate being easily damaged.

In addition, as a light guide plate having flexibility (flexibility) (referred to as a flexible light guide plate in this specification), a light guide plate made of silicone rubber or a resin composition mainly composed of an acrylic resin. A light guide plate is also proposed (see, for example, Patent Documents 1 to 3).
However, although the light guide plate made of silicone rubber is excellent in transparency, the mechanical strength is low, and particularly the tear strength is low, so that the light guide plate is easily damaged and easily torn.
In addition, the light guide plate mainly composed of acrylic resin is not only difficult to develop into a flexible light guide plate due to its brittleness, but also the emitted light when white light is incident due to the influence of catalyst residues during the synthesis of acrylic resin. There was a problem that became yellowish.

Furthermore, as other materials of the flexible light guide plate, transparent rubbers such as urethane rubber and urethane-based elastomer have been proposed (see, for example, Patent Document 3).
However, with flexible light guide plates made of urethane rubber, urethane elastomer, etc., even when white light is incident, the emitted light may be colored yellow, resulting in inferior light source color reproducibility and reduced display color reproducibility. Or the color of the print media on which advertisements are drawn cannot be accurately reproduced.

On the other hand, in Patent Document 4, in the light guide plate made of thermoplastic polyurethane resin, the light guide plate deteriorates (yellows), and as a result, the problem that the emitted light is colored yellow when white light is incident is solved. Therefore, it has been proposed to form a deterioration preventing layer made of an acrylic resin on the surface of the flexible light guide plate.
Thus, a flexible light guide plate made of polyurethane has already been proposed.

JP 2008-140698 A JP 2008-20748 A JP 2008-34337 A JP 2011-9125 A

However, as a result of repeated examination of the flexible light guide plate made of polyurethane by the present applicant, the problem that the emitted light is colored yellow when white light is incident is not only due to deterioration with time (yellowing) of polyurethane. However, immediately after molding the flexible light guide plate made of polyurethane, it is clear that even if the appearance is colorless and transparent, there may be a problem that the emitted light is colored yellow when white light is incident. became.

Therefore, the present applicant made extensive studies to solve the above problems, and thermally cured a urethane prepolymer obtained by reacting a specific polyol component and a specific isocyanate component in the presence of a non-amine catalyst. A flexible light guide plate made of thermosetting polyurethane has already been proposed (Japanese Patent Application No. 2011-085366). Such a flexible light guide plate made of thermosetting polyurethane has a small color difference between the incident light color and the emitted light color (excellent light source color reproducibility) for a long period from the beginning (initial), and emits light efficiently and uniformly. In addition, it is rich in flexibility and can be bent into an arbitrary shape.

On the other hand, the present applicant examined not only using white light as a light source but also using UV light as a light source for a flexible light guide plate made of such thermosetting polyurethane. When the flexible light guide plate is used as a surface light source for UV light, for example, when curing a UV curable resin composition applied to the surface of a three-dimensional processed product having a complicated surface shape, UV light is efficiently emitted. Expect to be able to irradiate. It can also be expected to be used as a light source for a sterilizer.
However, the flexible light guide plate made of the thermosetting polyurethane described above may be deteriorated by UV light when a UV-LED or the like is used as a light source.

Therefore, the present inventors have made further studies to provide a flexible light guide plate excellent in UV resistance, and in the flexible light guide plate made of the thermosetting polyurethane described above, polycarbonate polyol is used as a polyol component. By using an aliphatic polyisocyanate as the isocyanate component, the basic characteristics described above (the color difference between the incident light color and the emitted light color is small over a long period from immediately after production, and the light is efficiently and uniformly emitted, and the flexibility is increased. The present invention has been completed by discovering that it has an excellent UV resistance performance, and is capable of being bent and used in an arbitrary shape.
Moreover, the invention which concerns on the manufacturing method suitable for manufacturing such a flexible light-guide plate was also completed.

The flexible light guide plate of the present invention is a flexible light guide plate made of a thermosetting polyurethane obtained by thermosetting a polyol component, a polyisocyanate component and a curing agent in the presence of a non-amine catalyst,
The polyol component is a polycarbonate polyol,
The isocyanate component is an aliphatic polyisocyanate,
The thermosetting polyurethane is characterized in that the transmittance of light having a wavelength of 375 nm measured after UV irradiation is 80% / 3 mm or more.

In the flexible light guide plate of the present invention, the aliphatic polyisocyanate component is preferably isophorone diisocyanate.
In the flexible light guide plate, the thermosetting polyurethane preferably has a tan δ peak temperature of 50 ° C. or higher.

The manufacturing method of the 1st flexible light-guide plate of this invention is a method of manufacturing the said flexible light-guide plate,
After forming a silicone rubber layer inside a rotatable cylindrical mold, a material composition containing at least a polyol component, a polyisocyanate component, a curing agent, and a non-amine catalyst is poured into the mold, and The material composition is thermoset by rotating while heating the mold.

Moreover, the manufacturing method of the 2nd flexible light-guide plate of this invention is a method of manufacturing the said flexible light-guide plate,
A material composition containing at least a polyol component, a polyisocyanate component, a curing agent, and a non-amine catalyst is passed through a casting machine into a gap of a gap maintaining member that is continuously sent out by a pair of spaced apart rolls. The gap maintaining member holding the material composition in the gap is introduced into a heating apparatus, and the material composition is thermally cured while being held by the gap maintaining member.

In the method for manufacturing the second flexible light guide plate, the interval maintaining member is preferably made of a polyethylene terephthalate (PET) sheet.
In the method for manufacturing the second flexible light guide plate, the roll is preferably a heating roll.

Moreover, the manufacturing method of the 3rd flexible light-guide plate of this invention is a method of manufacturing the said flexible light-guide plate,
The groove portion of the molding drum that is rotated while being heated, provided with a groove portion engraved over the entire circumference of the outer peripheral surface of a material composition containing at least a polyol component, a polyisocyanate component, a curing agent, and a non-amine catalyst. The thermosetting polyurethane is discharged by being thermally cured in a state where the material composition is filled in a space portion formed by the groove portion and an endless belt that covers the groove portion and rotates following the forming drum. It is characterized by molding continuously.

The flexible light guide plate of the present invention is composed of a thermosetting polyurethane that uses a specific component as a polyol component and an isocyanate component and is thermoset in the presence of a non-amine catalyst. It is excellent in reproducibility, emits light efficiently and uniformly, and is flexible so that it can be bent into any shape.
In addition, the above thermosetting polyurethane has excellent durability against UV light because the polyol component is polycarbonate polyol and the isocyanate component is aliphatic polyisocyanate, and UV light is emitted from the UV light source using a UV-LED or the like. Even in this case, it is possible to maintain a high transmittance with respect to UV light over a long period of time, and to ensure a high transmittance over the entire short wavelength region to long wavelength region (380 to 780 nm). Can do.
In addition, the color difference between the incident light color and the emitted light color is small (excellent light source color reproducibility) for a long time from the beginning, and the light is efficiently and uniformly emitted, and it is flexible and used in an arbitrary shape. It is possible.
Furthermore, when used in an environment in which UV light is irradiated onto the flexible light guide plate, such as when used outdoors, it does not deteriorate over a long period of time and is excellent in reliability.
Moreover, according to the manufacturing method of the 1st-3rd flexible light-guide plate of this invention, the flexible light-guide plate of this invention which has the outstanding thickness precision and surface smoothness can be manufactured.

FIG. 1 is a perspective view schematically showing an example of a planar light source using the flexible light guide plate of the present invention. FIGS. 2A and 2B are both perspective views schematically showing an example of how the planar light source shown in FIG. 1 is used. Fig.3 (a) is sectional drawing which shows typically the centrifugal molding machine used with the manufacturing method of the flexible light-guide plate of 1st this invention, (b) is the sectional view on the AA line of (a). is there. 4 is a partial enlarged cross-sectional view of a portion B in FIG. FIG. 5 is a schematic view for explaining the method for producing the flexible light guide plate of the second present invention. (A) is sectional drawing which shows a 3rd manufacturing method typically, (b) is a perspective view which shows only the heating drum used with a 3rd manufacturing method, (c) is a 3rd It is sectional drawing which shows the state in the middle of hardening in this manufacturing method. FIG. 7 is a photograph showing the color tone when LED light is incident on the flexible light guide plates of Examples 1 and 6 and Comparative Examples 6 and 7 from the side surface on the width side.

Hereinafter, embodiments of the present invention will be described in detail.
First, the flexible light guide plate of the present invention will be described.
The flexible light guide plate of the present invention is a flexible light guide plate made of a thermosetting polyurethane obtained by thermosetting a polyol component, a polyisocyanate component and a curing agent in the presence of a non-amine catalyst,
The polyol component is a polycarbonate polyol,
The isocyanate component is an aliphatic polyisocyanate,
The thermosetting polyurethane is characterized in that the transmittance of light having a wavelength of 375 nm measured after UV irradiation is 80% / 3 mm or more.

Since the said flexible light-guide plate consists of thermosetting polyurethane, it becomes a flexible light-guide plate which is less distorted and excellent in transparency compared with what shape | molded the thermoplastic polyurethane.

The thermosetting polyurethane is obtained by thermosetting a polycarbonate polyol (polyol component), an aliphatic polyisocyanate (polyisocyanate component), and a curing agent in the presence of a non-amine catalyst.
The thermosetting polyurethane is obtained by thermally curing such a specific polyol component and a specific isocyanate component together with a curing agent in the presence of a non-amine catalyst. Even when UV light is introduced into the light guide plate using a UV-LED or the like, high UV light transmittance can be maintained over a long period of time, and the short wavelength region to long wavelength can be maintained. It is particularly excellent in that high transmittance can be ensured (transparency is ensured) over the entire region.
In addition, it is excellent in light source color reproducibility over a long period from the beginning, emits light efficiently and uniformly, and is flexible so that it can be bent into an arbitrary shape for use.

In the present invention, it is particularly important that the polyol component is a polycarbonate polyol. Use of such a polyol component is excellent in durability against UV light, and UV light is guided using a UV-LED or the like. Even when it is introduced into the optical plate, it is considered that it contributes most to the thermosetting polyurethane having the characteristic that high UV light transmittance can be maintained over a long period of time.
Moreover, since the said polyol component is a polycarbonate polyol, the said thermosetting polyurethane has the characteristic that it is excellent in water resistance (hydrolysis resistance), weather resistance, and heat resistance.

Examples of the polycarbonate polyol include polycarbonate glycol, polycarbonate triol, polycarbonate tetraol, derivatives in which side chains are introduced or branched structures are introduced, modified products, and mixtures thereof.

The polycarbonate polyol preferably has a number average molecular weight of 200 to 10,000.
The reason is that when the number average molecular weight is less than 200, the reaction is too fast and molding becomes difficult, or the molded article loses flexibility and becomes brittle. On the other hand, when it exceeds 10,000, the viscosity becomes too high and molding may become difficult, or the molded product may crystallize and become cloudy.

In the thermosetting polyurethane, the isocyanate component is an aliphatic polyisocyanate.
In the present invention, it is also important that the isocyanate component is an aliphatic polyisocyanate. This is because the thermosetting polyurethane can have excellent light source color reproducibility from the initial state.
Further, when the isocyanate component is an aliphatic polyisocyanate, the thermosetting polyurethane is discolored by light or heat emitted from the light source and light or heat from outside such as sunlight, and the light source color reproducibility is lowered (and, This does not cause problems such as a decrease in display color reproducibility due to this, a decrease in color reproducibility of print media on which advertisements are drawn, etc.) and a decrease in brightness of the light exit surface. Excellent light source color reproducibility can be maintained over a long period of time.
On the other hand, when the isocyanate component is an isocyanate component other than the aliphatic polyisocyanate, the above-described problems occur.

Examples of the aliphatic polyisocyanate include hexamethylene diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated MDI, isophorone diisocyanate, lysine diisocyanate, isopropylidenebis (4-cyclohexylisocyanate), norbornane diisocyanate, modified products and multimers thereof. Etc. These may be used alone or in combination of two or more.

Of these, isophorone diisocyanate is preferred.
This is because when the isocyanate component is isophorone diisocyanate, it is particularly suitable for securing a high transmittance for UV light and visible light before and after UV irradiation.

In addition, since isophorone diisocyanate is an aliphatic polyisocyanate, the thermosetting polyurethane is discolored by light and heat emitted from the light source and from the outside such as sunlight, and the light source color reproducibility is reduced (and This does not cause problems such as a decrease in display color reproducibility due to this, a decrease in color reproducibility of print media on which advertisements are drawn, etc.) and a decrease in brightness of the light exit surface. Excellent light source color reproducibility can be maintained over a long period from the initial state.

The curing agent is not particularly limited, and examples thereof include aliphatic or alicyclic low molecular weight glycols, triols such as trimethylolpropane and glycerin, and polyhydric alcohols such as pentaerythritol and sorbitol.
These may be used alone or in combination of two or more.

The thermosetting polyurethane is obtained by thermosetting in the presence of a non-amine catalyst.
Examples of the non-amine catalyst include organic tin compounds such as di-n-butyltin dilaurate, dimethyltin dilaurate, dibutyltin oxide, and octane tin, organic titanium compounds, organic zirconium compounds, carboxylic acid tin salts, and carboxylic acids. Examples thereof include bismuth acid salts.
And since the said non-amine catalyst is used, the said flexible light-guide plate is excellent in light source color reproducibility from an initial state (immediately after manufacture), and can maintain this outstanding reproducibility over a long period of time. It can be discolored for a long time.
On the other hand, in the thermosetting polyurethane obtained by using an amine-based catalyst as the catalyst, the emitted light tends to become yellow when white light is incident, and the appearance is colored over time. There is a problem that the reproducibility with respect to is also lowered.
As the non-amine catalyst, di-n-butyltin dilaurate and dimethyltin dilaurate are preferable. This is because good curing is exhibited with a small amount of addition.

The non-amine catalyst is preferably added to the material composition so as to be 0.0005 wt% to 3 wt%.
If the amount is less than 0.0005% by weight, the reaction rate cannot be sufficiently increased, and thus a molded product may not be obtained efficiently. On the other hand, if the amount exceeds 3% by weight, the reaction rate is too high, and thus uniform. It may not be possible to obtain a molded body having a thickness, the heat resistance and weather resistance of the molded body may be reduced, the light transmittance may be reduced, and the molded body may be colored. .

The thermosetting polyurethane is obtained by thermosetting a polycarbonate polyol, an aliphatic polyisocyanate, and a curing agent in the presence of a non-amine catalyst.
Here, the thermosetting polyurethane may be produced by a one-shot method, or may be produced by a prepolymer method or a pseudo-prepolymer method.

In the one-shot method, a polycarbonate polyol, an aliphatic polyisocyanate, and a curing agent are charged all together and cured to produce a thermosetting polyurethane molded body.
In the prepolymer method, a polycarbonate polyol and a stoichiometric excess amount of an aliphatic polyisocyanate are reacted to prepare a prepolymer having an isocyanate group at the terminal in advance, and a predetermined amount of a curing agent is mixed therewith. Then, a thermosetting polyurethane molded body may be prepared by curing the prepolymer.
In the pseudo-prepolymer method, a part of the polycarbonate polyol is mixed in advance with a curing agent, and a prepolymer is prepared from the remaining polycarbonate polyol and aliphatic polyisocyanate. What is necessary is just to produce the thermosetting polyurethane molded object by mixing and hardening these mixtures.

The thermosetting polyurethane may be prepared by any method. However, when the prepolymer method and the pseudo-prepolymer method are used, the prepolymer is a viscous liquid. When the thermosetting polyurethane is molded by the first to third manufacturing methods, scattering and undulation of the prepolymer is small. Therefore, the flexible light guide plate made of the thermosetting polyurethane has excellent surface smoothness and thickness accuracy. It becomes. Moreover, a flexible light guide plate can be obtained with a high yield.

The thermosetting polyurethane preferably does not contain an acrylic skeleton (acrylic skeleton or methacrylic skeleton).
Accordingly, the thermosetting polyurethane is preferably, for example, a thermosetting polyurethane excluding acrylic-modified polyurethane.
Thermosetting polyurethane with an acrylic skeleton may impair the flexibility of the polyurethane and reduce the mechanical strength such as abrasion resistance and tear strength. Furthermore, it is used to introduce an acrylic skeleton or an acrylic skeleton. This is because the emitted light may be colored (for example, yellow) due to the remaining catalyst.

In addition, the thermosetting polyurethane has various additives such as a colorant, a light stabilizer, a heat stabilizer, an antioxidant, an antifungal agent, a flame retardant, and the like as long as the required characteristics are not impaired. You may contain.

The thermosetting polyurethane has a transmittance of 375 nm wavelength light measured after UV irradiation of 80% / 3 mm or more.
By satisfying the above transmittance even after UV irradiation, the performance as a flexible light guide plate using a UV light source and / or used in an environment irradiated with UV light can be reliably ensured. Because it can.

In the present invention, the transmittance of light having a wavelength of 375 nm measured after UV irradiation is a value measured by the following method using a thermosetting polyurethane having a mirror-like surface and a thickness of 3 mm as a measurement sample.
That is, a process of irradiating UV light having a wavelength of 365 nm with 1037 mJ / cm ² for 10 seconds using a high-pressure mercury lamp lamp or the like is repeated at intervals of 10 seconds, and 25925 mJ / cm ² of UV light is irradiated to the thermosetting polyurethane for a total of 250 seconds. Then, the transmittance of 375 nm light (% / 3 mm) is a value measured using a spectrophotometer.
In this way, the UV resistance can be evaluated by intermittently irradiating the UV light to eliminate the influence of heat, and by irradiating the UV light with the above integrated light amount, it is practical to some extent. It is considered that UV resistance can be evaluated.

The thermosetting polyurethane has a light transmittance in the wavelength range of 400 to 500 nm of 80% or more and a light transmittance of 380 to 780 nm (400 to 500 nm) after UV irradiation using the same method as described above. The transmittance of light in the wavelength range of (except for) is preferably 80% or more.
Here, the wavelength range of 400 to 500 nm is a wavelength region where the light transmittance is particularly lowered in the thermosetting polyurethane, and when the flexible light guide plate of the present invention is used as a light guide plate for visible light, It is important that a high light transmittance of 80% or more is secured in the region. When the light transmittance is less than 80%, when white light is introduced, the emitted light is yellowish, so that the reproducibility of the light source color and the color of the print media is lowered.
Moreover, high light transmittance as the whole flexible light-guide plate is securable by making the transmittance | permeability of the light in the wavelength range of 380-780 nm (except 400-500 nm) 80% or more. When the transmittance is less than 80%, the light extraction efficiency is lowered, and the luminance of the light emitting surface may be lowered.
In this case, it means that there is no wavelength below the transmittance in the wavelength range.

The flexible light guide plate has an arithmetic average value of light transmittance of 80% or more measured every 1 nm in a wavelength range of 380 to 780 nm using a spectrophotometer, and in a wavelength range of 400 to 500 nm. It is also preferable that the arithmetic average value of the light transmittance measured every 1 nm is 80% or more.
This is also because, when satisfying such characteristics, the luminance of the light emitting surface is increased and the reproducibility of the light source color is excellent.

Further, the thermosetting polyurethane preferably has a light transmittance of 375 nm with respect to light transmittance before UV irradiation of 85% or more.
This is because the required characteristics as a light guide plate when using a UV-LED or the like as a light source can be sufficiently satisfied.

In addition, the light transmittance is 85% or more in the wavelength range of 400 to 500 nm before UV irradiation, and the light transmittance is 90% or more in the wavelength range of 380 to 780 nm (excluding 400 to 500 nm). Is also preferable. This is because the luminance of the light emitting surface is high and the reproducibility of the light source color is excellent.
Further, for the light transmittance before UV irradiation, the arithmetic average value of the light transmittance measured every 1 nm in a wavelength range of 380 to 780 nm using a spectrophotometer is 90% or more, and 400 to 500 nm. It is also preferable that the arithmetic average value of the light transmittance measured every 1 nm in the wavelength range is 85% or more. This is because the same effect is obtained in this case.

The thermosetting polyurethane preferably has a tan δ peak temperature (glass transition temperature Tg) of 50 ° C. or higher.
When the UV-LED is used as the light source for the flexible light guide plate of the present invention, the UV-LED generates heat up to about 80 ° C. Therefore, when the tan δ peak temperature is less than 50 ° C., the UV-LED -When LED is used as a light source, the flexible light guide plate becomes too soft.
The flexible light guide plate is usually used in combination with a sheet such as a reflection sheet, a diffusion sheet, a color filter, a prism sheet, a condensing lens sheet, a surface protection sheet, and an advertising medium. When the tan δ peak temperature is less than 50 ° C., the sheets are likely to be in close contact with the flexible light guide plate (thermosetting polyurethane). There is a possibility that an air pocket is generated between the light guide plate and the light emitting surface of the flexible light guide plate may not emit light uniformly.
The tan δ peak temperature is more preferably 55 ° C.
The peak temperature of tan δ may be measured using a dynamic viscoelastic property measuring apparatus.

The thermosetting polyurethane preferably has a JIS-A hardness of 90 to 99 °.
If the JIS-A hardness is less than 90 °, these sheets will stick to a part of the flexible light guide plate when used in combination with other sheets such as a reflection sheet and a diffusion sheet. This is because uniform light emission of the flexible light guide plate may be hindered. On the other hand, when the JIS-A hardness exceeds 99 °, the flexibility of the flexible light guide plate is reduced, and distortion and wrinkles are likely to remain when the flexible light guide plate is deformed.
More preferable JIS-A hardness is 90 to 95 °.

The flexible light guide plate of the present invention is made of such a thermosetting polyurethane.
The flexible light guide plate may be an edge light type light guide plate or a full pitch type light guide plate.

Although the thickness of the said flexible light-guide plate is not specifically limited, It is preferable that it is about 0.5-5 mm. If the thickness is less than 0.5 mm, the light source light may not be efficiently incident when used in an edge light system. On the other hand, if it exceeds 5 mm, flexibility may be impaired.
The thickness accuracy of the flexible light guide plate is preferably 0.1 mm or less, and more preferably 0.05 mm or less.

In the case of the edge light system, a reflective layer for reflecting the light inside the light guide plate toward the light emitting surface may be provided on the surface opposite to the light emitting surface of the flexible light guide plate. Here, the reflective layer can be formed, for example, by screen-printing a white paint containing titanium oxide particles, silica particles, precipitated barium sulfate particles and the like in a dot pattern.
The reflective layer may be formed by a gravure printing method or a patterning method using an ink jet or a drawing method using a dispenser. Furthermore, it may be formed by a method of providing irregularities using a V-groove cutter, a laser microfabrication device, or a water jet device, a method of transferring a mold having an irregular surface, or a reflective layer made of a cured resin by stereolithography. You may form by the method of laminating.
Of course, when using the flexible light guide plate of the present invention, a reflective sheet may be separately provided and used.

The surface shape of the flexible light guide plate is preferably a mirror surface. This is because a high-luminance and uniform light-emitting surface can be obtained.
Here, in order to make the surface of the flexible light guide plate into a mirror surface, for example, the flexible light guide plate may be manufactured by first to third manufacturing methods described later.

The said flexible light-guide plate is so preferable that yellowness (YI) is small. This is because as the yellowness (YI) increases, the light source color reproducibility decreases.
Specifically, the yellowness (YI) in the initial state is preferably 1.0 or less, and the reliability was obtained under the condition of standing for 1000 hours in a constant temperature and humidity chamber at a temperature of 60 ° C. and a relative humidity of 85%. The yellowness (YI) after the property test is preferably 3.0 or less.

The flexible light guide plate having such a structure is a surface light source used for lighting, advertisement display boards, electric signboards, electric bulletin boards, etc., a surface light emitter for UV irradiation, and further, a liquid crystal television, a personal computer, a mobile phone. Can be used for various applications such as light guide plates for liquid crystal displays, etc., but is particularly suitable as a planar light source (surface emitter) for irradiating UV light and a planar light source used outdoors. .

FIG. 1 is a perspective view schematically showing an example of a planar light source using the flexible light guide plate of the present invention. FIGS. 2A and 2B both use the planar light source shown in FIG. It is a perspective view which shows an example of an aspect typically.

As shown in FIG. 1, the flexible light guide plate 1 of the present invention has, for example, UV light from a UV-LED light source with support members 2 and 3 provided with UV-LED light sources (not shown) on both sides. Can be used as the planar light source 10A by holding the remaining edges with the flexible frames 4a and 4b.
A reflective layer (not shown) is formed on the back surface of the flexible light guide plate 1 (the lower surface in FIG. 1).

The planar light source 10A can be used as a cylindrical planar light source 10B that emits light on the inner surface side by deforming the flexible light guide plate 1 so as to be curved as shown in FIG. Moreover, as shown in FIG.2 (b), it can also be used as the circular-arc-shaped planar light source 10C by deform | transforming so that the flexible light-guide plate 1 may curve. Furthermore, when the flexible light guide plate is deformed into a cylindrical shape as shown in FIG. 2A, the outer surface may be deformed so that light is emitted.
Of course, since the flexible light guide plate of the present invention is excellent in flexibility (flexibility), it can be used by being deformed into an arbitrary shape as well as the shape shown in FIG.

Specific examples of usage include, for example, a three-dimensional processed product having a surface coated with a UV curable resin composition inside a cylindrical surface light source or inside an arc-shaped surface light source. An example of irradiating the three-dimensional processed product with UV light from the surroundings.

In addition, the flexible light guide plate of the present invention has, for example, the configuration shown in FIG. 1, without forming a reflective layer on the back surface, and separately providing a reflective sheet, or providing a diffusion sheet on the light emitting surface side. In addition, sheets such as a color filter, a prism sheet, a condensing lens sheet, a surface protective sheet, and an advertising medium may be appropriately disposed and used.
Conventionally known sheets can be used as these sheets.

Such a flexible light guide plate made of thermosetting polyurethane can be manufactured by, for example, the first to third methods of manufacturing the flexible light guide plate of the present invention described later. Each of these manufacturing methods is also one aspect of the present invention.

Next, the manufacturing method of a 1st flexible light-guide plate is demonstrated.
A manufacturing method of the first flexible light guide plate (also simply referred to as a first manufacturing method) is a method of manufacturing the flexible light guide plate,
After forming a silicone rubber layer inside a rotatable cylindrical mold, a material composition containing at least a polyol component, a polyisocyanate component, a curing agent, and a non-amine catalyst is poured into the mold, and The material composition is thermoset by rotating while heating the mold.

The first production method uses a centrifugal molding method in which a thermosetting material composition is poured and cured while rotating a heated rotatable cylindrical mold.

In the first manufacturing method, a centrifugal molding method is used. However, it is not necessary to use a new molding machine or mold for the centrifugal molding method, and it has been conventionally used as shown in FIG. A centrifugal molding machine 20 can be used. In the figure, 21 is a mold, 22 is a heat insulating chamber, 23 is a heater, 24 is a front door, and 25 is a rotating shaft.

In the first production method, first, a solvent-free two-component liquid silicone rubber is poured into the inside of the mold to form a molded body of the two-component liquid silicone rubber inside the mold.
FIG. 4 is a cross-sectional view schematically showing a part of a mold (corresponding to part B in FIG. 3) when centrifugal molding is performed by the first manufacturing method.

In the first manufacturing method, since the solvent-free two-component liquid silicone rubber is first poured into the mold 21, the silicone rubber layer 28 is formed on the inner surface of the mold 21 as shown in FIG. Since the silicone rubber layer 28 is first formed on the inner surface of the mold 21 by the two-component liquid silicone rubber having excellent releasability, the thermosetting polyurethane 27 formed thereon can be used without using any release agent. The flexible light guide plate can be peeled off very easily.
In the first production method, since a solvent-free two-component liquid silicone rubber to which no organic solvent is added is used, the health of the work environment can be kept good without harming the health of the worker.

The two-component liquid silicone rubber is not particularly limited, and examples thereof include a condensation type two-component liquid silicone rubber and an addition type two-component liquid silicone rubber. Of these, the condensed type is preferable. The addition-type two-component liquid silicone rubber has a rapid change in reaction rate due to temperature. For example, the curing reaction is too early at a temperature around 140 ° C. necessary for molding a thermosetting polyurethane. On the other hand, if a condensation type two-component liquid silicone rubber is used, the reaction rate can be easily controlled.

Here, the thickness of the silicone rubber layer 28 is preferably 0.5 to 3 mm. If the thickness is less than 0.5 mm, the thickness of the silicone rubber layer 28 is too thin to have strength, and when peeling from the mold, everything cannot be peeled cleanly. In some cases, heat cannot be effectively transferred, and the characteristics of the molded flexible light guide plate may be adversely affected.

In the first manufacturing method, the material composition of the thermosetting polyurethane is subsequently poured into the mold 21 and cured to produce the sheet-like thermosetting polyurethane. In this case, the thickness accuracy of the sheet-like material can be 0.1 mm or less.
Specifically, the polycarbonate polyol and aliphatic polyisocyanate (or urethane prepolymer comprising these), a curing agent, and a material composition containing a non-amine catalyst described above may be poured and cured. .

Here, the curing conditions may be set as appropriate according to the material composition, and are not particularly limited. For example, the curing conditions are a temperature: 60 to 160 ° C., a time: 5 to 180 minutes, and a rotation speed: 200 to 2500 rpm. Just do it.

According to the first manufacturing method, since a mirror-like surface is formed on the air side surface 28a of the silicone rubber layer 28 that has been poured first, the sheet of the thermosetting polyurethane 27 that has been molded by pouring the material composition subsequently. Both sides of the shaped product are mirror-like.
Further, in the first manufacturing method, when the solvent-free two-component liquid silicone rubber is poured into the mold without precisely processing the mold so that the deflection accuracy of the molding mold is good, The liquid silicone rubber is cured in the form of absorbing the vibration of the mold 21, and the silicone rubber layer 28 having the inner air side surface 28 a having a mirror surface and having high vibration accuracy is formed. Therefore, in the first manufacturing method, the thickness accuracy of the flexible light guide plate can be made extremely high, at least 0.1 mm or less.

In the first manufacturing method, after completion of the molding of the thermosetting polyurethane, the sheet-like material is taken out from the mold and cut into a predetermined size to obtain a flexible light guide plate.
In addition, after taking out from a metal mold | die, you may postcure.

Although it does not specifically limit as a method of cutting the thermosetting polyurethane of the said sheet-like material, For example, it is preferable to cut using an ultrasonic cutter.
This is because the cut surface can be made extremely smooth, and even when this cut surface is used as the light incident surface, the loss upon incidence can be kept small. Further, no polishing process is required.

Next, a method for manufacturing the second flexible light guide plate will be described.
A second flexible light guide plate manufacturing method (also simply referred to as a second manufacturing method) is a method of manufacturing the flexible light guide plate,
A material composition containing at least a polyol component, a polyisocyanate component, a curing agent, and a non-amine catalyst is passed through a casting machine into a gap of a gap maintaining member that is continuously sent out by a pair of spaced apart rolls. The gap maintaining member holding the material composition in the gap is introduced into a heating apparatus, and the material composition is thermally cured while being held by the gap maintaining member.

FIG. 5 is a schematic view schematically showing the second manufacturing method.
As shown in FIG. 5, in the second production method, the material composition 30a is drawn into a pair of spaced apart heating rolls 33a, 33b via a casting machine 31, and continuously sent out. The PET sheet 32a, 32b holding the material composition 30a is poured into the gap between the terephthalate sheets (PET sheets) 32a, 32b, and the material composition 30a is held by the PET sheets 32a, 32b. In this state, the sheet is thermoset to form a sheet of thermosetting polyurethane 30.

Here, the material composition 30a is the same as the material composition of the thermosetting polyurethane put into the mold by the first manufacturing method.
Further, the PET sheets 32a and 32b have a function as a gap maintaining member, and the gap can be maintained at a constant thickness. Thereby, since the material composition 30a held between the PET sheets 32a and 32b is cured in a state where a certain thickness is maintained, a sheet-like material of thermosetting polyurethane having excellent thickness accuracy is obtained. The thickness accuracy can be made 0.1 mm or less.

Further, when the material composition 30a is supplied from the casting machine 31, the position of the head part 31a of the casting machine 31 is from the central part of the heating rolls 33a and 33b (the central part of the gap formed by the PET sheets 32a and 32b). These are preferably unevenly distributed on the side of one of the heating rolls, and at this time, the uneven distribution distance is preferably not more than the radius of the heating roll. That is, it is preferable that the position directly below the head portion 31a of the casting machine 31 is located at any position from the central portion of the pair of heating rolls 33a and 33b to the center (axis) of one heating roll.
Moreover, it is preferable that the distance (distance with the nearest part of the surface of a heating roll) of the front-end | tip part of the head part 31a and the surface of a heating roll is 3 cm or less.
By disposing the head portion 31a at such a position, the thickness accuracy of the thermosetting polyurethane sheet-like material is further improved, bubbles are less likely to be mixed, and the mixed bubbles are easily removed. .

The heating rolls 33a and 33b are not necessarily heating rolls as long as at least the PET sheets 32a and 32b can be continuously fed out, and may have only a transport function, but are heating rolls. Is preferred.
In this case, since the material composition 30a starts to be cured immediately after being held in the gap between the PET sheets 32a and 32b, the thickness is more uniformly maintained until it is introduced into the heating device 36. This is because it is possible to produce a sheet-like material of thermosetting polyurethane having more excellent thickness accuracy.
Here, it is preferable to set the conveyance surface temperature of the heating rolls 33a and 33b to 10 to 60 ° C.
If it is less than 10 degreeC, while the viscosity of a material composition becomes high and it becomes difficult to remove a bubble, hardening reaction may become slow and the thickness precision of a molded product may fall, On the other hand, if it exceeds 60 degreeC, on a heating roll In some cases, the material composition may harden or bubbles may enter the molded product.

The heating device 36 is a heating furnace provided with a heater, and may be anything that can raise the temperature in the furnace to the curing temperature of the thermosetting polyurethane.
Moreover, the heating conditions (curing conditions) in the heating device 36 are not particularly limited, and may be appropriately set according to the composition of the material composition, for example, temperature: 40 ° C. to 160 ° C., time: 10 to 180 minutes. It is sufficient to perform under the conditions.

In FIG. 5, reference numeral 34 denotes a conveyance roller for sending out the PET sheets 32 a and 32 b, 35 denotes an auxiliary roller, and 37 denotes a conveyor belt for conveying the PET sheets 32 a and 32 b holding the material composition in the heating device 36. It is.

In the second manufacturing method, the gap maintaining member is not limited to a PET sheet, and may be, for example, a sheet-like material made of another resin material such as a polyolefin resin or a metal material.
However, it is preferable that the gap maintaining member is not subjected to a surface treatment such as a mold release treatment on the portion in contact with the material composition 30a, so that the formed thermosetting polyurethane sheet-like material can be peeled off. A PET sheet is preferred because of its superiority.
The reason why it is desirable that the mold release treatment or the like is not performed is to avoid that the mold release agent adheres to the surface of the flexible light guide plate made of the produced thermosetting polyurethane and the optical characteristics are deteriorated. The surface treatment may be performed as long as the treatment agent is not likely to adhere to the flexible light guide plate.
The gap maintaining member may be an endless belt that can be used continuously and repeatedly.
The material of the gap maintaining member needs to be selected according to the curing conditions. For example, when curing at a high temperature around 160 ° C., the gap maintaining member is made of a metal such as a steel belt. It is preferable to select a gap maintaining member.

In the second manufacturing method, after completion of the molding of the thermosetting polyurethane 30 (after unloading from the heating device), the sheet-like material is peeled off from the gap maintaining member and cut into a predetermined size to obtain a flexible light guide plate. it can.
In addition, after peeling from the gap maintaining member, post-curing may be performed.

The method for cutting the thermosetting polyurethane of the sheet-like material is not particularly limited, and the same method as the first production method can be used.

Next, a method for manufacturing the third flexible light guide plate will be described.
A third flexible light guide plate manufacturing method (also simply referred to as a third manufacturing method) is a method of manufacturing the flexible light guide plate,
The groove portion of the molding drum that is rotated while being heated, provided with a groove portion engraved over the entire circumference of the outer peripheral surface of a material composition containing at least a polyol component, a polyisocyanate component, a curing agent, and a non-amine catalyst. The thermosetting polyurethane is discharged by being thermally cured in a state where the material composition is filled in a space portion formed by the groove portion and an endless belt that covers the groove portion and rotates following the forming drum. It is characterized by molding continuously.

FIG. 6A is a cross-sectional view schematically showing a third manufacturing method, FIG. 6B is a perspective view showing only a heating drum used in the third manufacturing method, and FIG. It is sectional drawing which shows the state in the middle of hardening in a 3rd manufacturing method.

As shown in FIG. 6, in the third manufacturing method, first, the material composition 40 a is molded from the head portion 41 a of the casting machine 41 to the molding groove 51 of the molding drum 50 (see FIGS. 6B and 6C). Discharge inside.
At this time, the forming drum 50 rotates counterclockwise at a predetermined speed around the rotation shaft 53, and a necessary amount of material corresponding to the peripheral speed of the forming drum 50 and the depth and width of the forming groove 51 is obtained. The composition is continuously injected through the head portion 41a.
Here, the material composition 40a is the same as the material composition of the thermosetting polyurethane put into the mold by the first manufacturing method.

The material composition 40a is the same as the molding drum 50 after the curing reaction is started from the point a just below the head portion 41a of the molding drum 50 to the point b (position immediately before the start of contact of the endless belt 54). The molding endless belt 54 heated to the temperature is heated and held from the point b to the point c of the molding drum 50 to advance the curing reaction. Thereby, the curing reaction of the material composition 40a is almost completed, and the thermosetting polyurethane 40 having a necessary width and thickness and having a smooth mirror surface is formed.

The endless belt 54 is stretched over a preheating roll 56 that preheats the endless belt 54, a guide roll 58 that adjusts belt running, a tension roll 57 that applies tension to the endless belt 54, and a cooling roll 55 that cools the endless belt 54. It is configured to rotate in the same direction following the rotation of the forming drum 50.
Further, the preheating roll 56 is configured to be able to approach and separate from the forming drum 50, and is configured to be able to adjust the contact start point between the outer peripheral surface of the forming drum 50 and the endless belt 54, that is, the heating start position of the material composition. ing. Therefore, the heating time between points a and b can be finely adjusted without changing the peripheral speed of the forming drum 50 in response to the variation in the reactivity of the raw material composition.

Here, it is preferable that the molding drum 50 is heated to 100 to 150 ° C., and further, the speed is adjusted so as to rotate once in 30 to 300 seconds.
Moreover, it is preferable that the preheating roll 56 is heated at 100-150 degreeC.

Next, the molded thermosetting polyurethane 40 is peeled from the molding groove 51 of the molding drum 50 at the point c and guided onto the endless conveyor belt 61 a of the cooling conveyor 61. Here, since the endless conveyor belt 61a is cooled by the cooling device 64, the thermosetting polyurethane 40 is conveyed while being cooled to near normal temperature (around 20 ° C.) on the endless conveyor belt 61a. In the figure, 62 and 63 are rollers, and cooling water may be circulated therein.
Then, it can be set as a flexible light-guide plate by cutting the thermosetting polyurethane 40 to a predetermined size. In addition, before and after cutting the thermosetting polyurethane 40, post-curing may be performed as necessary.
The method for cutting is not particularly limited, and the same method as the first manufacturing method can be used.
As an example of a manufacturing apparatus used in the third manufacturing method, for example, an apparatus having the same configuration as the manufacturing apparatus disclosed in Japanese Patent Laid-Open No. 9-141761 can be used.

According to such first to third manufacturing methods, the flexible light guide plate of the present invention can be preferably manufactured by any method. Each of the first to third manufacturing methods is also one aspect of the present invention.

EXAMPLES Hereinafter, although an Example is hung up and demonstrated in more detail about this invention, this invention is not limited only to these Examples.

Example 1
(1) First, a predetermined amount (53.16 g) of isophorone diisocyanate (IPDI) is measured so that NCO% = 10.3 in advance with respect to 100 g of polycarbonate polyol having an average molecular weight of 2000 (Kuraray Polyol C2090, manufactured by Kuraray Co., Ltd.). I kept it.
Next, an equivalent ratio of 1,4-butanediol and trimethylolpropane is 40:60 so that NCO index = [NCO _IPDI ]-[OH _polyol ] / [OH _{curing agent} ] = 1.05. Addition and stirring of the curing agent (16.1 g) prepared in step 1 and a catalyst (Neostan U-100, manufactured by Nitto Kasei Co., Ltd.), and further adding and stirring isophorone diisocyanate, which has been measured in advance, are thermosetting. A composition for polyurethane was obtained.
The amount of the catalyst added was 0.05% by weight with respect to the entire thermosetting polyurethane.

(2) Apart from the above (1), a molding die drum (inner diameter: 700 mm, depth: 500 mm, runout accuracy at room temperature: 0.06 mm, number of rotations during molding: 800 rpm, rough surface state: Ra = 0. 30) is heated to 140 ° C., and a mixed liquid of TSE35 (main agent) and CE (curing agent) manufactured by GE Toshiba Silicone is cured as a two-component liquid silicone rubber material. The silicone rubber layer was formed by pouring into the molding die drum and heating and curing for 30 minutes. The obtained silicone rubber layer had a uniform mirror surface on the air side surface and a thickness of 0.7 mm.

(3) The material composition prepared in the above (1) is put into the molding die drum in which the silicone rubber layer is formed in the above (2), and cured by heating at a rotation speed of 1200 rpm and a heating temperature of 110 ° C. for 60 minutes. It was. Thereafter, post-crosslinking was carried out at 80 ° C. for 12 hours to obtain a polyurethane sheet having a thickness of 3 mm. The obtained polyurethane sheet had a uniform mirror surface on both surfaces.
Thereafter, the obtained polyurethane sheet was cut into 250 × 50 mm to complete a flexible light guide plate having a thickness of 3 mm.

(Examples 2 and 3)
A flexible light guide plate was produced in the same manner as in Example 1 except that the amount of isophorone diisocyanate relative to 100 g of the polycarbonate polyol was adjusted so that the NCO% corresponding to the complete prepolymer would be the value shown in Table 1.
The “complete prepolymer equivalent NCO%” represents the NCO% of the prepolymer assumed from the polyol and isocyanate.

(Examples 4 and 5)
A flexible light guide plate was produced in the same manner as in Example 1 except that the equivalent ratio of 1,4-butanediol and trimethylolpropane was changed as shown in Table 1.

(Example 6)
A flexible light guide plate was produced in the same manner as in Example 1 except that polycarbonate polyol having an average molecular weight of 2000 (Nippolan 982R, manufactured by Nippon Polyurethane Co., Ltd.) was used as the polyol component.

(Example 7)
A flexible light guide plate was produced in the same manner as in Example 1 except that the thermosetting polyurethane composition prepared by the following method was used.
1,4-butanediol and trimethylolpropane were added to a polycarbonate polyol / isophorone diisocyanate (IPDI) prepolymer (manufactured by Nippon Polyurethane Co., Ltd., HC242) so that NCO index = 1.05 with respect to 100 g of this prepolymer. A curing agent (10.5 g) prepared at an equivalent ratio of 40:60 and a catalyst (Neoto Chemical Co., Ltd., Neostan U-100) were added and stirred to obtain a thermosetting polyurethane composition.
The amount of the catalyst added was 0.05% by weight with respect to the entire thermosetting polyurethane.

(Comparative Example 1)
A flexible light guide plate was produced in the same manner as in Example 1 except that the thermosetting polyurethane composition prepared by the following method was used.
An equivalent ratio of 1,4-butanediol and trimethylolpropane was added to a polyether polyol / hydrogenated MDI prepolymer (DIC, GW1340) such that NCO index = 1.05 with respect to 100 g of this prepolymer. A curing agent (10.5 g) prepared at 40:60 and a catalyst (manufactured by Nitto Kasei Co., Ltd., Neostan U-100) were added and stirred to obtain a thermosetting polyurethane composition.
The amount of the catalyst added was 0.05% by weight with respect to the entire thermosetting polyurethane.

(Comparative Examples 2 to 5)
As an isocyanate component, instead of IPDI, H ₁₂ -MDI (hydrogenated MDI / hydrogenated diphenylmethane diisocyanate) was used in Comparative Example 2, and H ₆ -XDI (hydrogenated XDI / hydrogenated xylene diisocyanate) was used in Comparative Example 3, respectively. A flexible light guide plate was produced in the same manner as in Example 1 except that NBDI (norbornene diisocyanate) was used in Comparative Example 4 and HDI (hexamethylene diisocyanate) was used in Comparative Example 5.

(Comparative Examples 6 and 7)
As the isocyanate component, in place of IPDI, in Comparative Example 6, NBDI (norbornene diisocyanate) was used, and in Comparative Example 7, H ₆ -XDI (hydrogenated XDI / hydrogenated xylene diisocyanate) was used. Thus, a flexible light guide plate was manufactured.

(Comparative Example 8)
A flexible light guide plate was produced in the same manner as in Example 6 except that polytetramethylene ether glycol (manufactured by Hodogaya Chemical Co., Ltd., PTG2000SN) was used as the polyol component.

(Evaluation)
The following evaluation was performed about the flexible light-guide plate manufactured in Examples 1-7 and Comparative Examples 1-8. The results are shown in Table 1.

(1) JIS-A hardness Measured using a JIS-A type rubber hardness meter manufactured by Kobunshi Keiki. Note that four samples were stacked and adhered, and the thickness was measured at 12 mm.

(2) tan δ peak temperature was measured using a dynamic viscoelastic property measurement apparatus (TA Instruments, PSAIII). Here, the measurement conditions were as follows.
Temperature range: -60 ° C to + 100 ° C (2 ° C / min)
Frequency: 10Hz

(3) Light transmittance The light transmittance of light having a wavelength of 375 nm was measured using a spectrophotometer (manufactured by Hitachi High-Technologies Corporation, U-3500).
Moreover, the light transmittance for every 1 nm was measured in the wavelength range of 380 to 780 nm, and the arithmetic average value was calculated.
Each light transmittance is measured by repeating the process of irradiating UV light having a wavelength of 365 nm with 1037 mJ / cm ² for 10 seconds using a high pressure mercury lamp lamp before irradiating the flexible light guide plate with UV light at intervals of 10 seconds. , After irradiating 25925 mJ / cm ² of UV light for a total of 250 seconds.
Further, for the flexible light guide plates produced in Example 7 and Comparative Examples 1 and 8, the treatment of irradiating with 1055 mJ / cm ² of UV light with a wavelength of 365 nm for 10 seconds using a high-pressure mercury lamp was repeated at 10 second intervals for a total of 1630. This was performed after irradiating 171965 mJ / cm ² of UV light for a ^second .

(4) A flexible light guide plate cut into a color tone width 3 cm × length 6 cm × thickness 3 mm from edge light is used as a test piece, and an LED bar (MC-P35-3-30, 3 mm × 3 mm) is formed from the side surface on the width side. The white light was used and the color of the flexible light guide plate at that time was visually observed. Moreover, the photograph which image | photographed the color tone about the flexible light-guide plate of Examples 1 and 6 and Comparative Examples 6 and 7 was shown in FIG.

From the results of Examples and Comparative Examples, as in the flexible light guide plate of the present invention, by using polycarbonate polyol as a polyol component, it has excellent durability against UV light, and UV light is emitted using a UV-LED or the like. Even when a light source is used, it is clear that a high transmittance with respect to UV light can be maintained over a long period of time, and that a high transmittance can be secured over the entire short wavelength region to long wavelength region. It became.

DESCRIPTION OF SYMBOLS 1 Flexible light guide plate 2, 3 Support member 4a, 4b Frame 10A, 10B, 10C Planar light source 27, 30, 40 Thermosetting polyurethane 28 Silicone rubber layer 32a, 32b PET sheet 33a, 33b Heating roll 36 Heating apparatus 50 Molding drum 51 Molding groove 54 Endless belt 61 Cooling conveyor

Claims (8)

A flexible light guide plate comprising a thermosetting polyurethane obtained by thermosetting a polyol component, a polyisocyanate component and a curing agent in the presence of a non-amine catalyst,
The polyol component is a polycarbonate polyol,
The isocyanate component is an aliphatic polyisocyanate,
The flexible light guide plate, wherein the thermosetting polyurethane has a transmittance of light having a wavelength of 375 nm measured after UV irradiation of 80% / 3 mm or more. The flexible light guide plate according to claim 1, wherein the aliphatic polyisocyanate component is isophorone diisocyanate. The flexible light guide plate according to claim 1, wherein the thermosetting polyurethane has a peak temperature of tan δ of 50 ° C. or higher. It is a manufacturing method of the flexible light-guide plate in any one of Claims 1-3,
After forming a silicone rubber layer inside a rotatable cylindrical mold, a material composition containing at least a polyol component, a polyisocyanate component, a curing agent and a non-amine catalyst is poured into the mold, A method for producing a flexible light guide plate, wherein the material composition is thermoset by rotating while heating a mold. It is a manufacturing method of the flexible light-guide plate in any one of Claims 1-3,
A material composition containing at least a polyol component, a polyisocyanate component, a curing agent, and a non-amine catalyst is passed through a casting machine into a gap of a gap maintaining member that is continuously sent out by a pair of spaced apart rolls. A flexible light guide plate is produced, wherein the gap maintaining member holding the material composition in the gap is introduced into a heating device, and the material composition is thermally cured while being held by the gap maintaining member. Method. The manufacturing method of the flexible light-guide plate of Claim 5 which the said space | interval maintenance member consists of a polyethylene terephthalate (PET) sheet. The method for manufacturing a flexible light guide plate according to claim 5, wherein the roll is a heating roll. It is a manufacturing method of the flexible light-guide plate in any one of Claims 1-3,
The groove portion of the molding drum that is rotated while being heated, provided with a groove portion engraved over the entire circumference of the outer peripheral surface of a material composition containing at least a polyol component, a polyisocyanate component, a curing agent, and a non-amine catalyst. The thermosetting polyurethane is discharged by being thermally cured in a state where the material composition is filled in a space portion formed by the groove portion and an endless belt that covers the groove portion and rotates following the forming drum. A method for producing a flexible light guide plate, wherein the flexible light guide plate is continuously formed.