JP2001318213A - Reflection member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent clouding of a reflection plane and wrinkles and blisters of a reflection film in a folded and bent part in a reflection member, using a reflective material consisting of a reflection film, an adhesive layer and a support body. SOLUTION: At least reflection film (A), adhesive layer (D), and supporting body (E) are formed successively, and an adhesive or a pressure-sensitive adhesive, having >=0.1 and <=5 dynamic loss tangent (tanδ) at 1 Hz frequency at room temperature, is used for the adhesive layer (D).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bent reflecting member and a reflector using the same.

[0002] The reflecting member of the present invention is a lamp reflector for a backlight of a liquid crystal display device, a printer and a facsimile.
It is used for a reflector used for a mirror, a reflector for a fluorescent lamp, a reflector for a strobe, and the like. Other than these, it can be used for almost all light reflecting members to be bent.

[0003]

2. Description of the Related Art Generally used reflectors include sheets,
There are various shapes such as plates and molded bodies. A flat sheet is used for a suitable purpose, and a complicated shape having many curved surfaces is used for a molded object. A plate-shaped reflector that can be punched and bent can be easily processed and, because it is more rigid than a sheet, can retain its shape, and is therefore used for various purposes. In particular, it is used for a backlight lamp reflector of a liquid crystal display (LCD), a reflector for a fluorescent lamp, and the like. LCDs are becoming thinner, lighter, have larger screens, and have higher brightness. In response, LCD backlights have higher lamp brightness and higher density of members. The miniaturization of reflectors and the complexity of processing shapes are progressing, and the bending diameter during bending is becoming smaller.

[0004] In a reflection member in which an inorganic thin film is laminated on a plate-like substrate in multiple layers, countless fine cracks are likely to occur in the bent portion even when the bending diameter is large. Even in a reflection member in which organic thin films are stacked, similar cracks are likely to occur depending on the hardness of the organic thin film used. Such cracks may cause not only a change in the reflection characteristics but also a decrease in the durability of the reflection member. Reflectors with a structure in which a plate-shaped support and a reflective film are laminated can be easily manufactured by bonding with an adhesive or a pressure-sensitive adhesive, and can be combined with various plate-shaped substrates, so that they can be used properly according to the purpose of use. Is possible. A reflecting member formed by bending a reflector having such a structure can be used without any problem when the bending diameter is large, but when the bending diameter becomes, for example, about 4 mm in diameter, cloudiness of the reflection surface at the bent portion, The wrinkles and floating of the reflective film are likely to occur.

[0005]

The opacity of the bent portion, wrinkles and floating of the reflection film, which are caused by bending the reflection member having a configuration in which the plate-like substrate and the reflection film are laminated, change the reflection characteristics. May be caused. Also, LC
Since the density of the backlight unit for D is increasing, even a slight wrinkle or floating of the reflection film may cause a problem in use. Therefore, a reflecting member is required that does not cause opacity, wrinkles or floating of the reflective film in the bent portion even when the bending process is performed.

[0006]

The above object is achieved by the present invention described below.

That is, the present invention provides (1) at least:
A reflecting member which is formed of a reflecting film (A), an adhesive layer (D), and a support (E), and which is formed by bending the reflecting film (A) side of the ADE as a reflecting surface and the reflecting film (A) side as an inner side. Wherein the mechanical loss tangent (tan δ) of the adhesive or pressure-sensitive adhesive used for the adhesive layer (D) is 0.1 to 5 at room temperature and a frequency of 1 Hz, or (2) a reflective film (A). ) Is composed of a transparent polymer film (B) and a metal thin film layer (C).
And the reflective member according to (1), wherein the transparent polymer film (B) side is a reflective surface, or (3) the reflective film (A) is inwardly bent when bent at 180 ° with a diameter of 4 mm. (1) The reflective member according to any one of (1) and (2), in which no white turbidity, floating of the reflective film, and wrinkles occur, or (4) punching is performed.
(1) to (4), wherein the reflecting member according to any one of (1) to (3), or (5) the reflecting film (A) is bent inward and installed so as to cover the light source. The reflective member described above is a gist.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, referring to the attached drawings, FIGS. 1 and 2 are sectional views showing the structure of a reflection member according to the present invention.
The reflection member referred to here is a member using a reflector that returns incident light to the original medium. The reflector here mainly returns 80% or more of light in the visible region to the original medium. An object, more preferably an object that returns 90% or more of light in the visible region to the original medium. In FIG. 1, light incident on the reflective film 10 is reflected on the surface of the reflective film 10 and returns to the original medium again. FIG. 2 shows the reflection film 1
0 is a case where the metal thin film layer 30 is formed on the transparent polymer film 20, and most of the light incident from the transparent polymer film 20 side passes through the transparent polymer film 20 and 30, the metal thin film layer 30
, And passes through the transparent polymer film 20, and returns to the original medium again. As a method for manufacturing the reflection member shown in FIG. 1, there is a method in which an adhesive layer 40 is applied to the reflection surface opposite to the reflection surface of the reflection film 10 and the adhesive surface and the support 50 are laminated.

As the reflection film, a white reflection film or FIG.
As shown in FIG. 2, a reflective film in which a metal thin film layer 30 as a reflective layer is formed on a transparent polymer film 20 is used. More preferably used is a reflective film in which a metal thin film layer is formed on a transparent polymer film. For the metal thin film layer, a metal having high reflectivity such as silver, aluminum, or an alloy thereof is used. Silver having high reflectivity is preferably used.

The transparent polymer film 20 includes polyethylene (PE), polystyrene (PS), polyethylene terephthalate (PET), and polyether sulfone (PE).
S), polycarbonate (PC), cellulose triacetate-based resin, polyarylate-based resin, polysulfone-based resin, and the like can be used, but are not necessarily limited thereto, provided that they are transparent and have a somewhat high glass transition temperature. Can be used. Further, if necessary, additives such as an ultraviolet absorber, an adhesion promoter, and a wetting property improver may be mixed.

Further, the surface of the transparent polymer film may be subjected to a physical and chemical surface modification treatment such as a corona discharge treatment, a glow discharge treatment, a surface chemical treatment and a surface roughening treatment. Although the thickness of the transparent polymer film is not limited, a thickness of about 25 to 100 μm is preferably used. When the thickness is smaller than this value, there is no problem in performance as a reflection member, but the handling property is poor. If the thickness is larger than this value, wrinkling or floating of the film is likely to occur when the film is bent. The optical characteristics of the polymer film used are wavelength 5
The light transmittance at 50 nm is preferably 80% or more. More preferably, the light transmittance is 80% or more for light in the wavelength range of 500 to 700 nm, and still more preferably, the light transmittance is 80% or more for light in the wavelength range of 350 to 750 nm. If the light transmittance is lower than this value, the reflectance when used as a reflecting member falls below 90%, which is not preferable in terms of performance as a reflecting member.

The method for forming the metal thin film layer includes a wet method and a dry method. The wet method is a general term for the plating method, and is a method of depositing a metal such as silver from a solution to form a film. Specific examples include a silver mirror reaction. On the other hand, the dry method is a general term for a vacuum film forming method, and specific examples thereof include a resistance heating type vacuum deposition method, an electron beam heating type vacuum deposition method, an ion plating method, and an ion beam assisted vacuum deposition method. And a sputtering method. In particular, a vacuum film forming method capable of a roll-to-roll method for continuously forming a film is preferably used in the present invention.

In the vacuum deposition method, a metal raw material is melted by an electron beam, resistance heating, induction heating, or the like, the vapor pressure is increased, and the metal is deposited on the surface of the base material at preferably 0.1 mTorr (about 0.01 Pa) or less. At this time, a gas such as argon may be introduced at a pressure of 0.1 mTorr (about 0.01 Pa) or more to cause high frequency or direct current glow discharge.

In the sputtering method, a DC magnetron sputtering method, an rf magnetron sputtering method, an ion beam sputtering method, an ECR sputtering method, a conventional rf sputtering method, a conventional DC sputtering method, or the like can be used. In the sputtering method, a raw material may be a metal plate target such as silver or aluminum, and the sputtering gas may be helium, neon, argon, krypton, or the like.
Xenon or the like can be used, but preferably argon is used. The purity of the gas is preferably at least 99%, more preferably at least 99.5%.

The thickness of the metal thin film layer is 70 nm to 300 n.
m is preferable, and more preferably 100 nm to 200 nm.
It is. If the thickness is much smaller than this value, the film thickness is not sufficient, so that there is light to be transmitted and the reflectance is reduced. In particular, when aluminum is used, it is oxidized in the environment and the reflectance is reduced. On the other hand, if the thickness is too large beyond this value, the reflectance does not increase, showing a tendency to saturate, and the adhesion of the metal thin film layer to the polymer film is undesirably reduced. The metal thin film layer has a degree that does not harm the performance,
Metals such as gold, copper, nickel, iron, cobalt, tungsten, molybdenum, tantalum, chromium, indium, manganese, and titanium may be included.

The film thickness can be measured by a stylus roughness meter, a repetitive reflection interferometer, a microbalance, a quartz oscillator method, etc.
The crystal oscillator method is suitable for obtaining a desired film thickness because the film thickness can be measured during film formation. There is also a method in which the conditions for film formation are determined in advance, a film is formed on a sample substrate, the relationship between the film formation time and the film thickness is examined, and the film is controlled by the film formation time.

The metal thin film layer may have a multilayer structure in which other metals, alloys, oxides thereof, or the like are laminated in addition to the reflective layer for the purpose of protecting the rear surface of the reflective layer. The present inventors have already disclosed that when silver is used for the metal thin film layer, it is preferable that the polymer film has a property of absorbing ultraviolet rays in order to improve the light resistance of silver (Japanese Patent Application Laid-Open (JP-A) No) 5-162227, US-5276600).
In addition, before forming the silver thin film layer, the surface of the transparent polymer film on which the silver thin film layer is formed is subjected to a surface treatment using a plasma containing a metal, and then a silver film is formed, thereby increasing the light-heat resistance of the reflector. The present inventors have already disclosed that they are preferable in terms of improvement (JP-A-09-150482).

The thus obtained reflective film and a support are laminated with an adhesive (including an adhesive). The adhesive is applied to the opposite side of the reflection surface of the reflection film. When a silver reflective film is used, since the transparent polymer film side is the reflective surface, an adhesive layer is applied to the metal thin film layer side. As the adhesive used for the lamination, one having a mechanical loss tangent (tan δ) at room temperature (about 25 ° C.) at room temperature and a frequency of 1 Hz at the time of measurement of 0.1 to 5 is used. More preferably, 0.5 or more is used.

Tan δ is expressed by the following equation. tan δ = E ″ / E ′ E ′: dynamic elastic modulus, E ″:
If the dynamic loss tan δ is lower than the value shown, floating and wrinkling of the reflective film are likely to occur at the bent portion when the reflective member is bent. Further, when a silver reflection film is used as the reflection film, the reflection surface is likely to be clouded at the bent portion. If the value is higher than the indicated value, workability deteriorates.

The type of the adhesive is a polyester-based adhesive,
Acrylic adhesives, urethane adhesives, silicone adhesives, epoxy adhesives, and the like can be used, but are not limited to these types, as long as they have practical adhesive strength. Specific examples include SK Dyne 5273 manufactured by Soken Chemical Co., Ltd. as a polyester-based adhesive, Bond KU10 manufactured by Konishi Co., Ltd., and EPOX AH-602 manufactured by Mitsui Chemicals, Inc. as a polyurethane-based adhesive. Adhesive strength measured at 180 ° peeling is 100 g / cm
The above is sufficient, preferably 500 g / cm or more, more preferably 1000 g / cm or more.
If it does not reach 100 g / cm, when the reflector is bent to a radius of curvature of about 1 to 5 mm, a situation such as the reflection film rising from the support is caused, which is not preferable.

The thickness of the adhesive is 0.5 μm to 50 μm.
μm is preferred, more preferably 1 μm to 20 μm, and still more preferably 2 μm to 10 μm. If the thickness is too large, the cost increases from the viewpoint of material costs, which is not preferable. If it is too thin, sufficient adhesive strength cannot be obtained.

Examples of the method of applying the adhesive include a bar coating method, a Meyer bar coating method, a reverse coating method, a gravure coating method, and a die coating method. The selection is made in consideration of the coating speed, the obtained surface condition, and the like.

The lamination is generally carried out after the application of the adhesive, but in addition, the application step and the lamination step can be carried out separately. For example, when using a thermoplastic polyester adhesive, lamination can be performed at any time by melting the applied adhesive with a hot roll or the like.

Although the support is not particularly limited, a metal plate is particularly preferably used in consideration of shape retention.
Examples of the metal plate used as the support include an aluminum plate, an aluminum alloy plate, a brass plate, a stainless steel plate, a steel plate, and the like, but are not necessarily limited thereto, and are selected according to the use of the reflection member. For example, aluminum is lightweight, has excellent workability, and has high thermal conductivity, which can effectively release the heat applied to the atmosphere. Therefore, aluminum is suitably used as a reflection member used in backlights of LCDs such as notebook computers. it can. Since aluminum alloy is lightweight and has high mechanical strength, it can be suitably used as a reflection member also serving as a structural member. Since stainless steel has high mechanical strength and excellent corrosion resistance, it is suitably used for applications requiring a thinner material, such as a reflection member used outdoors. Brass (brass), that is, a copper-zinc alloy, has a high mechanical strength and is easily used for soldering, so that it is suitably used for a reflection member requiring grounding. Since steel plates are inexpensive, they are suitably used for reflectors for fluorescent lamps, which are applications in which cost is prioritized.

The thickness of the metal as the support is preferably thin from the viewpoint of cost reduction and easiness of bending, and is preferably thick from the viewpoint of ease of lamination with a reflective film or the like and shape retention. The preferred thickness of the metal plate is 0.05 mm to 5 mm, more preferably 0.1 mm to 5 mm.
mm to 0.8 mm.

The reflective member of the present invention may be provided with a transparent protective layer on the reflective surface side of the reflective film. With such a protective layer, the influence of external environmental factors such as surface hardness, light resistance, gas resistance, and water resistance of the reflection member can be further suppressed. Examples of substances that can be used to form such a protective layer include, for example, acrylic resins such as polymethyl methacrylate, polyacrylonitrile resins, polymethacrylonitrile resins, silicone resins such as polymers obtained from ethyl silicate, polyesters, and the like. In addition to organic substances such as resins and fluororesins, inorganic substances such as silicon oxide, zinc oxide and titanium oxide are useful.

As a method for forming the transparent protective layer, existing methods such as coating and laminating a film can be used. In addition, the thickness of the transparent protective layer is required to exhibit a protective effect within a range that does not reduce the light reflectivity and does not impair the flexibility, and is appropriately changed depending on the material and application. Can be The plate-shaped reflector obtained as described above is punched and bent to form a reflection member.

The reflecting member installed and used so as to cover the light source can be manufactured, for example, by punching and punching a desired shape into a desired shape from a flat plate material, and then bending. Bending is a method of bending a plate material along a straight edge. For example, V-shaped bending and U-shaped bending using a press, and folding using a tangent bender are used.

The above-mentioned processing method is used to set the transparent polymer film side inward and to cover the light source. The reflecting member to be used is, for example, a lamp reflector of a backlight of a liquid crystal display device, a printer, a facsimile, and the like. And a reflector for fluorescent lamps and a reflector for strobe.

The lamp reflector of the backlight of the liquid crystal display device is installed and used so as to cover a lamp (cold cathode tube) as shown in FIG. 3, and has a U-shaped or U-shaped cross section. Often have. The reflection member thus obtained was bent at a bending diameter of 4 mm, and the bent portion was observed. As a result, no opacity of the reflection surface, wrinkles and floating of the reflection film were observed.

[0031]

The present invention will be described below with reference to examples. Transparent polymer film (Teijin Co., Ltd.)
Polyester film, Tetron film type HB
3, thickness 25 μm, total light transmittance = 88.1%), on a target of 99.99% purity silver and 99.5% purity argon as sputtering gas by DC magnetron sputtering. One formed to have a thickness of 150 nm was used. An aluminum plate having a thickness of 0.3 mm was used as a support.

The adhesive was applied to the silver surface of the reflection film using a bar coater (No. 20). After drying to evaporate the solvent, the solution was passed through a heated laminating roll together with the support, and then laminated by a hot press. The evaluation was performed by measuring the adhesive strength between the reflective film and the support, and conducting a bending test.

Since the measurement of the adhesive strength is performed in the state of a flat plate,
The punching process and the bending process were performed on the reflection plate. The sample was cut to a width of 1 cm, and the reflective film was cut from the support at a crosshead speed of 50 mm / min. At 180 °. For measurement, Orientec Co., Ltd. Tensilon U
CT-5T was used.

A bending test sample may be evaluated by bending it into a lamp reflector shape, but it is difficult to evaluate since the lamp reflector shape varies depending on the type of LCD backlight. Therefore, instead of the bending, bending was performed using a bending tester described in JIS K-5400, and the state of the bent portion was observed. This bending tester was used to evaluate the bending resistance of the coating film, and was used because it was bent at a constant bending diameter. The bending diameter was 2 mm and 4 mm.

The mechanical loss tangent of the adhesive was measured as follows. The adhesive was dried and cured to prepare a sample having a length of about 22 mm, a width of about 3 mm, and a thickness of about 0.03 to 0.6 mm, and RSA2 manufactured by Rheometrics Inc. Dynamic viscoelasticity measurement and temperature dispersion (strain control) ) Measured in tensile mode. The measurement conditions were a temperature rise of 3 ° C. per minute, a set temperature of −80 to 150 ° C., a frequency of 1 Hz, and an Air atmosphere.

Example 1 A solvent type hot melt type polyester adhesive having a tan δ at 25 ° C. of 0.99 was used.

Example 2 A two-pack, room-temperature-curing, solvent-type polyurethane adhesive having a tan δ of 0.19 at 25 ° C. was used.

Example 3 A three-part thermosetting solvent type epoxy adhesive having a tan δ of 0.13 at 25 ° C. was used.

[Comparative Example] The tan δ at 25 ° C. was 0.1.
05, a two-part cold-setting epoxy adhesive was used. With respect to the samples obtained in Examples 1 to 3 and Comparative Example, an adhesive strength measurement and a bending test were performed. Table 1 shows the results.

[0040]

[Table 1] From Table 1, it can be seen that when an adhesive having a mechanical loss tangent of 0.1 or more and 5 or less is used, there is no problem even if the adhesive is bent at 4 mm in diameter.

[0041]

By using an adhesive or pressure-sensitive adhesive having a mechanical loss tangent (tan δ) of not less than 0.1 and not more than 5 at a frequency of 1 Hz at room temperature in a laminate of the reflective film and the support, the bent portion can be formed. As a result, it was possible to suppress the occurrence of white turbidity on the reflection surface, wrinkles and floating of the reflection film.

[Brief description of the drawings]

FIG. 1 is a structural sectional view of a reflecting member of the present invention.

FIG. 2 is a structural sectional view of a reflecting member of the present invention.

FIG. 3 is a schematic view showing an example of a use example of a reflection member according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Reflective film 20 Transparent polymer film 30 Metal thin film layer 40 Adhesive layer 50 Support body 60 Light guide plate 70 Reflecting member (lamp reflector) 80 Lamp

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03B 15/02 G03B 15/02 K 15/05 15/05 F term (Reference) 2H042 DA04 DA11 DA21 DC02 DC07 DC11 DD05 DE04 2H053 CA08 4F100 AB01C AB10 AK01A AK41 AK41G AR00A AT00B BA03 BA07 BA10A BA10B CB00 CB03 EH66 GB90 JK14 JK20G JM02C JN01A JN06A YY00G

Claims (5)

[Claims] At least the reflecting film (A) side of the ADE comprising the reflecting film (A), the adhesive layer (D) and the support (E) is a reflecting surface, and the reflecting film (A) side is an inner side. In the bent reflective member, the adhesive or the adhesive used for the adhesive layer (D) has a mechanical loss tangent (tan δ) of 0.1 or more and 5 or less when the frequency is 1 Hz at room temperature. 2. The reflection film (A) according to claim 1, wherein the reflection film (A) has a constitution BC composed of a transparent polymer film (B) and a metal thin film layer (C), and the transparent polymer film (B) side is a reflection surface. Reflective member 3. The reflective film (A) side inward and the diameter of 4
3. The reflecting member according to claim 1, wherein the reflecting member does not have white turbidity, floating of the reflecting film, and wrinkles when bent at 180 ° in mm. 4. The reflecting member according to claim 1, wherein punching is performed. 5. The reflection member according to claim 1, wherein the reflection film (A) side is bent inward and installed so as to cover the light source.