JPH11198284A - Light reflecting element excellent in press processability - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light reflecting element (plate) easy to produce and hardly released between a film having a silver membrane layer high in light reflectivity formed thereto and a metal support in a press molding process such as bending processing, punching processing, squeeze processing or the like. SOLUTION: A light reflecting element excellent in press processability is obtained by laminating a polyester resin film with a thickness of 5-50 μm and an m.p. of 160-250 deg.C to the single surface of an aluminium thin plate and thermally fusing the surface having a silver membrane layer not formed thereto of a biaxially stretched polyethylene terephthalate film with a thickness of 20-60 μm having the silver membrane layer formed to single surface thereof to the surface of the polyester resin film within a temp. range of 240-280 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light reflector (or light reflector) having excellent press workability. More specifically, the present invention relates to a light reflector suitable as a reflector such as a fluorescent lamp.

[0002]

2. Description of the Related Art A light reflecting film using a flexible substrate such as a plastic film is light in weight and excellent in flexibility.
What is bonded to a metal thin plate such as an aluminum thin plate by pressing, etc.
Demand for a high-reflecting plate for a fluorescent lamp, a reflecting plate for a backlight of a liquid crystal display device, and the like, in particular, as a liquid crystal display device has been made thinner and smaller, the demand for a reflecting plate (body) for a backlight is expanding.

Conventionally, as a light reflector (light reflector), a metal support such as an aluminum thin plate is formed into a curved surface in advance by press working such as bending, and a light reflecting film is inserted into the inside of the curved surface to form an adhesive. Many materials fixed via an agent are used. However, the work of inserting and fixing a film formed of a metal thin film of high reflectivity such as silver or aluminum on the surface of a metal support at a predetermined position on a curved surface that has been subjected to a bending process is very complicated. Yes, and the inserted film is shifted,
There were drawbacks such as a decrease in the brightness as a light reflector.

Further, as a light reflector, a highly reflective metal thin film is formed on a flexible film on a metal support such as an aluminum thin plate via a thermosetting adhesive such as epoxy or urethane. A laminated body in which the formed films are laminated is prepared in advance, and the laminated body is subjected to press working such as bending, punching, and drawing to obtain a target light reflector. However, the light reflector manufactured by this method is subjected to a pressing process such as a bending process, a punching process, and a drawing process.
There is a disadvantage that the adhesion (adhesion) surface between the metal support and the film on which the high-reflectance metal thin film is formed is easily peeled off.

[0005]

Under such circumstances, the present inventors have made intensive studies to provide a light reflector which has solved the above-mentioned disadvantages all at once, and as a result, have completed the present invention. Things. The objects of the present invention are as follows. (1) Light reflector (light reflector) that is easy to manufacture and has excellent brightness
To provide. (2) In a pressing process such as a bending process, a punching process, and a drawing process, an adhesive (adhesion) surface between a film on which a high-reflectance metal thin film is formed and a metal support is hardly peeled off. Reflector).

[0006]

According to the present invention, a polyester resin film having a thickness of 5 μm to 50 μm and a melting point of 160 ° C. to 250 ° C. is laminated on one side of an aluminum thin plate. On the surface of the polyester resin film, a surface on which a silver thin film layer is formed on one surface and the silver thin film layer of a biaxially stretched polyethylene terephthalate film having a thickness of 20 μm to 60 μm is formed at 240 ° C. Provided is a light reflector excellent in press workability, which is characterized by being thermally fused in a temperature range of up to 280 ° C.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
In the present invention, examples of the aluminum thin plate include a thin plate made of an alloy of aluminum and magnesium (5000 series) and an alloy of aluminum and manganese (3000 series) according to JIS H4000 from the viewpoint of workability and strength. However, the present invention is not limited to this. In addition, the surface of the thin aluminum plate is subjected to normal chromate treatment,
Chemical treatments such as zirconium treatment and titanate treatment,
Physical surface treatment such as electrolytic etching may be performed. The thickness of the thin plate can be selected in a range of 0.1 mm to 0.8 mm, and a thickness of 0.15 mm to 0.45 mm is particularly preferable.

[0008] A biaxially stretched polyethylene terephthalate film (hereinafter abbreviated as "film B") having a silver thin film layer formed on one side of the aluminum thin plate (hereinafter may be abbreviated as "a thin plate A"). Are sometimes laminated), and a polyester resin film (C) is interposed between the two.
Place. The polyester resin film (hereinafter sometimes abbreviated as “film C”) has excellent adhesion to the film B and functions to reinforce the strength of the film B. That is, when the film B is directly laminated on the thin plate A by heat, the film B is thermally degraded and the adhesive strength is reduced. Even if the film B is laminated on the thin plate A at a low temperature in order to prevent the thermal deterioration of the film B, the bonding (adhesion) surface is not strong enough to withstand the press working.

The above polyester resin film (C)
In the polyester resin, a part of repeating units of polyethylene terephthalate and ester is terephthalic acid, phthalic acid, isophthalic acid, oxalic acid,
One or more acid components such as succinic acid, glutaric acid, adipic acid, pimelic acid, speric acid, azelaic acid, sebacic acid and dodecadionic acid;
Polyhydric alcohols such as 1,2-propylene glycol, 1,4-butanediol, 1,5-pentadiol, 1,6-hexadiol, diethylene glycol, and triethylene glycol. And a copolymer with polyethylene terephthalate. The polyester resin is not limited to those exemplified above as long as the melting point is in the range of 160 to 260 ° C. A resin additive such as an ultraviolet ray can be added to the polyester-based resin as needed.

The polyester resin has a melting point of 160 ° C.
It must be in the range of 250 ° C. If the melting point exceeds 250 ° C., it is necessary to heat the film B to a temperature exceeding 250 ° C. when heat-sealing the film B to the film C, so that the adhesion (adhesion) force with the film B is reduced, and the press of the light reflector is performed. A peeling phenomenon is likely to occur in the processing step.
When the temperature is lower than 60 ° C., the adhesion (adhesion) strength is low, and especially the adhesion (adhesion) strength under high temperature and high humidity is low, and both are not preferable.

The thickness of the polyester resin film (C) is selected in the range of 5 μm to 50 μm. If the thickness is less than 5 μm, the adhesive strength between both the thin plate A and the film B cannot be improved, and the film B
The function to reinforce the strength is not sufficient, which is not preferable. If the thickness exceeds 50 μm, the film (C) itself becomes too hard and small cracks are generated in the step of pressing the light reflector, which is not preferable.

The light reflector (light reflector) according to the present invention is formed by laminating a biaxially stretched polyethylene terephthalate film (film B) having a silver thin film layer formed on one surface on the surface of a film C. The film B is laminated on the thin plate A and performs a function of reflecting light. Film B has a thickness of 2
A silver thin film layer is formed on one side of a biaxially stretched polyethylene terephthalate film of 0 μm to 60 μm. If the thickness of the film B is less than 20 μm, not only is the strength insufficient and it is difficult to form a silver thin film layer, but also the lamination with the film C becomes difficult. Film B
If the thickness exceeds 60 μm, small cracks are generated in the step of pressing the light reflector, which is not preferable.

In order to form a silver thin film layer on one side of a biaxially stretched polyethylene terephthalate film, silver atoms are formed by evaporating silver atoms and attaching them to the film surface. Can be performed by a method such as The thickness of the silver thin film layer is 100 to
A range of 1000 angstroms is preferred. If the thickness of the silver thin film layer is less than 100 angstroms, the reflectance is inferior, and if it exceeds 1000 angstroms, the bending processability is poor, such as cracks occurring during the bending process.

The lamination of the biaxially stretched polyethylene terephthalate film (film B) having a silver thin film layer on the surface of the film C is preferably performed by a heat fusion method. The temperature at the time of heat fusion shall be selected in the range of 240 ° C to 280 ° C. When the temperature at the time of heat fusion is less than 240 ° C,
The adhesion (adhesion) between the biaxially oriented polyethylene terephthalate film having a silver thin film layer is poor, and when the temperature exceeds 280 ° C., the adhesion (adhesion) between the silver thin film layer and the biaxially oriented polyethylene terephthalate layer decreases. This is likely to cause a peeling phenomenon in the press working step, which is not preferable. When heat-sealing to the surface of the film C, the surface of the film B where the silver thin film layer is not formed is heat-sealed.

According to an experiment, a thin film made of an epoxy resin, a fatty acid or a hydroxy-substituted phenol was heat-treated on a surface of the thin plate A in advance at a temperature of 300 to 500 ° C. (hereinafter referred to as “coating D”). (May be abbreviated as).
It turns out that the power can be greatly improved. According to an experiment, when a thin metal plate is bonded to a resin film, when used as a thermosetting adhesive such as a polyester resin, a urethane resin, or an alkyd resin, the adhesive strength with the film B is high. It was found that peeling occurred during press workability, which was not preferable. In addition, when these thermosetting adhesives are used, there is a drawback that the equipment becomes large because a solvent is used.

According to experiments, when an aluminum thin plate and a resin film are bonded together, an ethylene-acrylic acid copolymer resin, an ethylene-ethyl acrylate copolymer resin, and an ethylene-methyl methacrylate copolymer resin are used. When a thermoplastic type thermo-adhesive resin such as ionomer is used, the adhesion between the two is good, but when the resin film is a biaxially stretched polyethylene terephthalate film having a silver thin film layer, both of them are used. It was found that the adhesion (adhesion) was poor.

As the epoxy resin for forming the coating D,
For example, bisphenol-type epoxy resins, more specifically, bisphenol A monoglycidyl ether, bisphenol A glycidyl ether and the like can be mentioned. In addition, various epoxy resins such as bisphenol F type and resosyl type epoxy resin can be used. The epoxy resin preferably has a molecular weight of about 300 to 3000 and an epoxy equivalent of 150 to 3200.

The fatty acid forming the film D is generally RCOOH (R is a saturated or unsaturated hydrocarbon).
And may contain a lower fatty acid and a higher fatty acid. Lower grades are obtained by chemical synthesis, and those with R of 6 or more are obtained by hydrolysis of natural fats and oils. Specifically, palmitic acid,
Stearic acid, oleic acid, lauric acid, myristic acid,
Examples include behenic acid, but are not limited to those exemplified. Hydroxymethyl-substituted pheno-
Examples of alcohol include salicylic acid alcohol, o-hydroxymethyl-p-cresol and the like.

In order to form the film D on the thin plate A, it is necessary to apply the above-mentioned epoxy resin, fatty acid or hydroxymethyl-substituted phenol to the surface of the thin aluminum plate, heat-treat it, and thermally denature it. The method of applying to the surface of the aluminum thin plate varies depending on the form of the thin plate surface.For example, in the case of a plate, the epoxy resin or the like is used alone or with an organic solvent such as methyl ethyl ketone, acetone, toluene, and trichlene. After dilution, gravure roll method, reverse roll method, kiss roll method, air
An ordinary coating method such as a knife coating method or a dip coating method can be used.

The amount of coating varies depending on the type of the aluminum sheet, etc.
It can be selected in the range of 1 μm to 10 μm. When the thickness is less than 0.01 μm, sufficient adhesive strength cannot be obtained, and peeling occurs during press workability.
When the ratio exceeds the above range, the peel strength is lowered, and both are not preferable. A particularly preferred range in the above range is from 0.02 μm to
7 μm.

In order to form the film B on the surface of the thin plate A, first, a film D is formed on the surface of the thin plate A, or a film C is formed without forming the film D. The method for forming the film C on the surface of the thin plate A depends on the form of the surface of the thin plate A, but a coat hanger attached to the tip of the extruder.
A die, a T-die, a die such as an I-die, and a lamination while the extruded film is in a molten state are generally applied by a melt lamination method. In addition, a separately manufactured film C is used. The method of laminating on the thin plate A, the method of laminating the separately manufactured film C on the surface of the thin plate A heated above the softening temperature of the film C, thermocompression with a nipple, and the method of crimping with a press machine can be used. it can.
As described above, it is preferable to laminate the film B on the surface of the film C by the heat fusion method.

The light reflector according to the present invention is processed into a desired shape by a press working method such as bending, punching, drawing or the like, and is used as a reflector for a copying machine, a high light reflector for a fluorescent lamp,
It is suitably used for applications such as a reflector for a backlight of a liquid crystal display device.

[0023]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the present invention is limited to the following Examples without departing from the spirit of the invention.

In the following description examples, the evaluation of the resin-coated light reflector (light reflector) was performed by the following method. (1) Adhesion: A method of visually observing whether or not peeling of a film from a metal thin plate is observed when a 6 mm extrusion is performed using a drawing Erichsen tester based on JIS Z2247.
When no peeling of the film was observed, it was judged as "good", and when peeling of the film was observed, it was judged as "poor".

(2) Punching workability: A disc having a diameter of 100 mm is punched from a resin-coated light reflector, and the punched end face is visually observed. Those recognized were judged as x. (3) Impact resistance: 1/2 '× 5 on the laminated surface of the film using a Dupont impact tester based on JIS K5400.
A method of applying a shock of 00 g × 500 mm and visually observing whether or not peeling of the film from the metal thin plate was observed. When the peeling of the film was not observed, it was judged as ○, and when the peeling of the film was observed, it was judged as ×. did.

(4) Bendability: When the aluminum thin plate of the resin-coated light reflector is bent outward by 180 ° using a vise bending tester based on JIS Z2248, peeling of the film from the thin metal plate at the bent portion. By a method of visually observing whether or not the film was observed, it was judged that the film was not peeled off, and that the film was peeled was evaluated as x.

(5) Drawing workability: A disk-shaped resin-coated light reflector having a diameter of 99 mm is disposed on the film side, and the diameter (d) is 55 mm, the length (L) is 20 mm, and the capacity is Drawing into a cylindrical container of about 20 liters (D / d = 1.8, L /
D = 0.2), after drawing, a method of visually observing whether or not peeling of the film from the metal thin plate was observed. X was determined.

(6) Durability (moisture resistance test): A # -type notch is formed on the film surface of the resin-coated light reflector, and an Erichsen test piece extruded 4 mm from the aluminum thin plate side is prepared. After leaving for 500 hours under the condition of a humidity of 95%, a method of visually observing whether or not the film was peeled was observed. Judged.

(7) Durability (heat resistance test): A # -type notch is formed on the film surface of the resin-coated light reflector, and an Erichsen test piece extruded 4 mm from the aluminum thin plate side is prepared. After standing for 500 hours under the conditions, the film was visually observed to determine whether or not peeling of the film was observed. When no peeling of the film was observed, it was judged as ○, and when the peeling of the film was observed, it was judged as ×.

[Test Examples 1 to 6] An aluminum thin plate having a thickness of 0.2 mm (JIS H4000 A3004)
P) A bisphenol-type epoxy resin (molecular weight: 380, epoxy equivalent: 180-200) was dissolved in tricrene on one side of (thin plate A), and this solution was applied to a thickness of 1 μm by a roll coater method. And then apply the epoxy resin coating surface of this aluminum thin plate to 3
Heat treatment was performed at 50 ° C. to form a heat-modified coating (coating D). A 15 μm-thick polyester resin film (trade name: Melinex 850, manufactured by ICI Japan) (film C) was laminated at a temperature of 250 ° C. on the surface of the heat-modified coating of the aluminum thin plate to form a laminate.

A biaxially stretched polyethylene terephthalate film (manufactured by Reiko Co., Ltd., having a thickness of 42 μm) having a silver thin film layer formed on the surface of the polyester resin film (film C) of the laminate obtained above. Name: Ruil Mira-37W
01) (Film B) at 150 ° C. (Test Example 1), 20
0 ° C (Test Example 2), 230 ° C (Test Example 3), 260 ° C
(Test Example 4) Lamination was performed at temperatures of 290 ° C. (Test Example 5) and 300 ° C. (Test Example 6). The various evaluation tests described above were performed on the obtained laminate. The results are shown in Table 1.

[0032]

[Table 1]

From Table 1, the following becomes clear. (1) The light reflector having a temperature of 260 ° C. when the film B is thermally fused to the film C laminated on the surface of the thin plate A is used for pressing such as adhesion, impact, bending, punching, and drawing. It is also excellent in workability, durability (moisture resistance, heat resistance), etc. (see Test Example 4). (2) On the other hand, if the temperature at the time of heat fusion is 240 ° C. or less, the obtained light reflector has press workability such as adhesion, impact, bending, punching, and drawing. When the temperature at the time of heat fusion exceeds 280 ° C., the obtained light reflector is inferior in durability (moisture resistance, heat resistance) and the like (see Test Examples 1 to 3). Is inferior in drawability (see Test Examples 5 and 6).

[Test Examples 7 to 10] 0.2 mm in thickness
On one surface of an aluminum thin plate (same type as used in Test Example 1) (thin plate A), a trichlorene solution of the same type of bisphenol-type epoxy resin as used in Test Example 1 was roll-coated.
The coating method is applied by a tar method so that the coating thickness becomes 1 μm.
Then, the surface of the thin aluminum plate coated with the epoxy resin was heated at 200 ° C. (Test Example 7), 250 ° C. (Test Example 8), 30 ° C.
Heat treatment was performed at 0 ° C. (Test Example 9) and 350 ° C. (Test Example 10) to form a heat-modified coating (coating D). A 15 μm-thick polyester resin film (same type as used in Test Example 1) (Film C) was
The laminate was laminated at a temperature of 50 ° C. to form a laminate.

On the surface of the polyester resin film (film C) of the laminate obtained above, a biaxially stretched polyethylene terephthalate film (same type as used in Test Example 1) having a thickness of 42 μm (film B) Were laminated at a temperature of 250 ° C. The various evaluation tests described above were performed on the obtained laminate. Table 2 shows the results.

[0036]

[Table 2]

The following becomes clear from Table-2. (1) When laminating the film C on the surface of the thin plate A, if the thermal denaturation temperature of the coating D interposed therebetween is 300 ° C. or more, the light reflector has adhesion, impact properties, bending, Excellent in press workability such as punching and drawing, durability (moisture resistance, heat resistance), etc. (Test Example 9 and Test Example 1)
0). (2) On the other hand, when the thermal denaturation temperature of the coating D is lower than 300 ° C., the obtained light reflector is inferior in press workability such as adhesion, impact, bending, punching, and drawing. In addition, the durability (moisture resistance, heat resistance) and the like are also inferior (see Test Examples 7 and 8).

[Test Examples 11 to 14] Thickness: 0.2
mm thin aluminum plate (same type as used in Test Example 1)
On one side of (thin plate A), a polyester resin film (same type as used in Test Example 1) (film C) having a thickness of 15 μm was laminated at 250 ° C. Next, a biaxially oriented polyethylene terephthalate film having the silver thin film layer (same type as used in Test Example 1) (film B) was heated at 200 ° C.
(Test Example 11), 220 ° C. (Test Example 12), 240 ° C.
(Test Example 13) and laminated at a temperature of 260 ° C. (Test Example 14). The various evaluation tests described above were performed on the obtained laminate. The results are shown in Table-3.

[0039]

[Table 3]

From Table 3, the following becomes clear. (1) When laminating the film C on the surface of the thin plate A,
When the film D is not formed on the surface of the film C, and the lamination temperature of the film C is 240 ° C. or less, the obtained light reflector has a pressing property such as adhesion, impact property, bending, punching, and drawing. Poor workability and durability (moisture resistance, heat resistance)
(See Test Examples 11 to 12). (2) On the other hand, even if the coating D is not formed on the surface of the thin plate A, if the lamination temperature of the film C is 240 ° C. or 260 ° C., the obtained light reflector is slightly inferior in drawability. However, it is excellent in adhesion, impact resistance, bending, durability (moisture resistance, heat resistance), etc. (see Test Examples 13 to 14).

[Test Examples 15 and 16] A thickness of 0.2
mm thin aluminum plate (same type as used in Test Example 1)
On one side of (thin plate A), a polyester resin film (manufactured by Toa Gosei Co., Ltd., trade name: Alonmelt PES111EEF
(Melting point = 120 ° C.) (Test Example 15), 128E (melting point =
150 ° C.) (Test Example 16)
Laminated at a temperature of ° C. Next, a biaxially stretched polyethylene terephthalate film (same type as used in Test Example 1) having a silver thin film layer and having a thickness of 42 μm (Film B) was prepared as follows.
Each was laminated at a temperature of 0 ° C. The various evaluation tests described above were performed on the obtained laminate. The results are shown in Table-4.

[Test Example 17] A polyester film (manufactured by Diafoil Hoechst, trade name: Diafoil) was placed on one side of an aluminum thin plate (same type as used in Test Example 1) (thin plate A) having a thickness of 0.2 mm. T100E, melting point = 260
° C) (film C) was laminated at a temperature of 280 ° C. Next, a biaxially stretched polyethylene terephthalate film (same type as used in Test Example 1) (film B) having a silver thin film layer and having a thickness of 42 µm was laminated at a temperature of 280 ° C.
The various evaluation tests described above were performed on the obtained laminate. The results are shown in Table-4.

[0043]

[Table 4]

Table 4 shows that the melting point of the resin of the film C (polyester resin) laminated on the surface of the thin plate A is 160 ° C.
If it is lower, the drawability and durability (moisture resistance, heat resistance) of the obtained light reflector are inferior (Test Example 1).
5, see Test Example 16), and when the melting point is higher than 250 ° C., it is also apparent that the drawability, durability (moisture resistance, heat resistance) and the like of the obtained light reflector are similarly deteriorated (see FIG. 5). See Test Example 17).

[0045]

The present invention has been described in detail above, and has the following particularly advantageous effects, and its industrial utility value is extremely large. 1. The light reflector (plate) according to the present invention does not employ a method in which a light reflection film is inserted inside a curved surface formed in advance and fixed via an adhesive as in a conventional product, and a silver thin film is previously formed on an aluminum thin plate. Since the biaxially stretched polyethylene terephthalate film on which the layer is formed is laminated via a polyester resin film, the production is easy and the luminance is excellent. 2. In the light reflector (plate) according to the present invention, the bonding (adhesion) surface between the film on which the high-reflectance metal thin film is formed and the metal support is formed by a pressing process such as bending, punching, or drawing. It is hard to peel off and has excellent press workability. 3. The light reflector (plate) according to the present invention is obtained by heat-treating a thin film made of an epoxy resin, a fatty acid or a hydroxy-substituted phenol between a thin aluminum plate and a polyester resin film in a temperature range of 300 ° C to 500 ° C. When a modified coating is interposed, the adhesion (adhesion) force between the aluminum thin plate and the polyester resin film is improved, which is preferable.

Claims (2)

[Claims] 1. An aluminum thin plate having a thickness of 5
A polyester resin film having a melting point of 160 ° C. to 250 ° C. having a thickness of 20 μm to 60 μm and a silver thin film layer formed on one surface and a thickness of 20 μm to 60 μm is laminated on the polyester resin film. A light reflector excellent in press workability, characterized in that a surface of a stretched polyethylene terephthalate film on which a silver thin film layer is not formed is heat-fused in a temperature range of 240 ° C to 280 ° C. 2. An aluminum thin plate having a thickness of 5 μm to 5 μm.
A thin film made of an epoxy resin, a fatty acid or a hydroxy-substituted phenol is placed between a polyester resin film having a melting point of 160 ° C. and 250 ° C.
The light reflector excellent in press workability according to claim 1, wherein the light reflector is formed by laminating with a heat-modified coating heat-treated in a temperature range of 0 ° C interposed therebetween.