JPH0557831A - Optical laminated sheet and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide optical laminated sheet having extremely excellent surface flatness, especially electrode substrate for producing liquid crystal display panel the industrially profitable manufacturing method of said optical laminated sheet. CONSTITUTION:After resin solution for forming crosslinkable resin hardened material layer is cast on lower layer, the cast solution is dried so as to bring the amount of residual solvent in semi-dried coating to 5-100wt.% of the absolute dry weight of the coating. Biaxially stretched polyethylene terephthalate film having the surface roughness of 0.004mum is brought into contact under pressure- contacting state with the semi-dried coating (2a) from above and, in succession, the hardening of the coating by drying is proceeded. Thus, the optical laminated sheet concerned having crosslinkable resin hardened material layer, the surface roughness of the free surface of which is 0.1mum or less, is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical laminated sheet having extremely excellent surface smoothness, and more particularly to an electrode substrate for producing a liquid crystal display panel. The present invention also relates to a method for industrially producing such an optical laminated sheet.

[0002]

2. Description of the Related Art Conventionally, glass has been used as a substrate for liquid crystal display transparent electrodes, but it cannot be made thin.
Due to problems such as inferior impact resistance and difficulty in mass production, plastic substrates have recently been used more frequently, and the applicant has also filed several applications as described below. There is.

For example, in Japanese Patent Laid-Open No. 63-71829, an aqueous anchor coat layer is provided on at least one surface of a base material layer made of a sheet of polycarbonate resin or the like and having a retardation value of 30 nm or less. There is shown an electrode substrate for a liquid crystal display panel, in which a single-layer or multi-layer protective layer made of a cured product of an air-permeable resin and / or a crosslinkable resin is provided thereon.

In JP-A-64-50021, a laminate of a gas-permeable synthetic resin film layer and a cured crosslinkable resin layer is adhered to each other with their gas-permeable synthetic resin film layer surfaces facing each other. An electrode substrate for a liquid crystal display panel is shown which has a structure in which it is laminated and integrated via an agent layer.

In JP-A-64-50022, a cross-linking agent capable of reacting with the gas-permeable synthetic resin film layer is used on both sides of the gas-permeable synthetic resin film layer formed by a casting method. There is disclosed a method for producing an electrode substrate for a liquid crystal display panel, in which the cured crosslinkable resin layer is directly formed by a casting method.

Japanese Patent Laid-Open No. 2-137922 discloses a retardation value of 30 having a resin layer having no solvent resistance.
For the production of liquid crystal display panels in which an alcohol-soluble UV-curable adhesive layer or a water-based thermosetting adhesive layer is laminated on the resin layer side of a substrate sheet having a thickness of nm or less, and a release sheet is further laminated on the adhesive layer. Is shown as an example of a base sheet, and a sheet having a layer structure of a resin sheet such as polycarbonate / anchor coating layer / air-permeable synthetic resin layer / phenoxyether-based crosslinked polymer layer is shown as an example of the base sheet. I have been given.

In Japanese Patent Application Laid-Open No. 2-149819, the electrode support film side of an electrode support film with a transparent electrode having a structure in which a transparent electrode is provided on one surface of an electrode support film that can be wound into a roll is referred to as a retardation value. Shows a liquid crystal cell substrate with a transparent electrode laminated and integrated on a base material having a light transmittance of 80 nm or less and a light transmittance of 60% or more. As an example of an electrode supporting film, a resin film layer / anchor coating layer / crosslinking is shown. Cured resin layer, resin film layer / anchor coating layer / air permeable synthetic resin film layer / crosslinkable resin cured product layer, crosslinkable resin cured product layer / air permeable synthetic resin film layer / anchor coating layer / resin film Layer / anchor coating layer / air-permeable synthetic resin film layer / crosslinkable resin cured material layer, crosslinkable resin cured material layer / air-permeable synthetic resin layer Film having a layer structure such as a film layer / adhesive layer / penetration resistance temper synthetic resin film layer / crosslinkable resin cured material layer is raised.

[0008]

When the above-mentioned sheet-like substrate is used as an electrode substrate for manufacturing a liquid crystal display panel, a transparent electrode such as ITO is formed on the cured crosslinkable resin layer, and further thereon. After the alignment film is provided on, the liquid crystal cell is assembled. In this case, the liquid crystal that can be contained between the substrates is TN.
In the case of (twisted nematic) liquid crystal, some irregularities on the substrate surface on the transparent electrode formation side have almost no effect on product quality. This is because a liquid crystal display panel assembled from a liquid crystal cell using TN liquid crystal has an achromatic color, and if the light and shade are clear, the panel is acceptable.

However, when the liquid crystal contained between the substrates is STN (super twisted nematic) liquid crystal, the STN liquid crystal twists about 270 ° although the gap between the substrates is only about 5 to 6 μm. Therefore, even if there is a slight unevenness on the substrate surface on the transparent electrode forming side, the display is colored purple, green, etc. and the screen becomes very difficult to see. It was the biggest weakness of LCD panels. The electrode substrate according to the applicant's application cited above has not sufficiently solved this problem.

Under such a background, the present invention provides an optical laminated sheet excellent in surface smoothness, particularly an electrode substrate for producing a liquid crystal display panel, and
It is an object of the present invention to provide a method for industrially producing such an optical laminated sheet.

[0011]

The optical laminated sheet of the present invention is a laminated sheet having a resin layer (2) formed by a cast film forming method on the outer layer side, wherein the resin layer (2) is free. The surface roughness of the surface is 0.5 μm or less, the retardation value is 60 nm or less, and the visible light transmittance is 60% or more.

Further, in the method for producing an optical laminated sheet of the present invention, after the resin solution for forming the resin layer (2) is cast on the lower layer (1), the residual solvent amount in the semi-dried film (2a) is reduced. Dry to 5 to 100% by weight of the absolute dry coating, contact the crimping material (3) with a surface roughness of 0.5 μm or less on the semi-dry coating (2a) in the crimped state, and then dry. It is characterized by advancing curing.

The present invention will be described in detail below.

As the resin constituting the resin layer (2), various kinds of resins can be used as long as they can be dissolved in a solvent to form a coating film. However, the purpose of the resin substrate is to manufacture an electrode substrate. In this case, heat resistance, solvent resistance, transparent electrode forming property and the like are required, and therefore it is particularly desirable to use a resin composition in which a crosslinking agent is mixed with a crosslinking agent.

Examples of such crosslinkable resins include phenoxyether type crosslinkable resins, epoxy resins, acrylic resins, acrylic epoxy resins, melamine resins, phenol resins and urethane resins. Of these, as typical examples, a phenoxyether type crosslinkable resin and an acrylic resin will be described in detail.

Among the crosslinkable resins, a particularly preferable resin is a phenoxy ether type polymer represented by the following chemical formula 1.

[0017]

[Chemical 1]

(Wherein R ^{1 to} R ⁶ are each hydrogen, a lower alkyl group having 1 to 3 carbon atoms or Br, R ⁷ is a lower alkylene group having 2 to 4 carbon atoms, m is an integer of 0 to 3, n is 2
It means an integer of 0 to 300, respectively. )

A phenoxyether-type crosslinked polymer is obtained by subjecting the hydrogen portion of the hydroxyl group of this polymer to a crosslinking reaction with a polyfunctional compound as a crosslinking agent. As the cross-linking agent (polyfunctional compound) to be reacted to obtain a cross-linked polymer, a group having a high reaction activity with a hydroxyl group, for example, an isocyanate group,
A compound having two or more carboxyl groups, a reactive group in the carboxyl group (for example, a halide, an active amide, an active ester, an acid anhydride group, etc.), mercapto or the like is used, and polyisocyanate is particularly important. ..

As the acrylic resin, a compound containing at least three or more acryloyloxy groups or / and methacryloyloxy groups in the molecule (hereinafter referred to as a polyfunctional (meth) acryloyloxy group-containing compound) is a main component. A composition containing a polyfunctional unsaturated monomer and / or an initial radical reaction product thereof as a main component can be mentioned. Particularly preferred is a polyfunctional unsaturated monomer containing at least 3 or more (meth) acryloyloxy groups in the molecule, in an amount of 50% by weight or more based on all unsaturated monomers,
A composition comprising an unsaturated monomer mixture or / and its initial radical reactant, which is preferably contained in an amount of 70% by weight, particularly preferably 90% by weight or more.

When the resin layer (2) is a cured crosslinkable resin layer, its thickness is usually 2 to 500 μm, preferably 3
It is often set to μm to 200 μm.

The surface roughness of the free surface of the resin layer (2) is 0.5 μm.
m or less, preferably 0.2 μm or less, more preferably
It is set to 0.1 μm or less. Generally, the surface roughness of a melt-extruded film is 3 to 4 μm for a film having a thickness of 100 μm, and the surface roughness of a cast film is 2-3 μm for a film having a thickness of 100 μm. A method of making the surface roughness so small that it can be said that it is beyond common sense will be described later.

The resin layer (2) has a retardation value of 60 nm or less, preferably 30 nm or less, and a visible light transmittance of 60% or more, preferably 70% or more, considering that it is used for optical applications. Is required.

The optical laminated sheet of the present invention is preferably
After casting the resin solution for forming the resin layer (2) on the lower layer (1), the amount of residual solvent in the semi-dry coating (2a) was 5% of the absolute dry coating weight.
To 100% by weight, and at the same time, the surface roughness of the semi-dry coating (2a) is 0.5 μm or less, preferably
Contact the crimping material (3) of 0.15 μm or less in the crimped state,
Then, it is manufactured by proceeding with dry curing.

Examples of the lower layer (1) include a base material layer, an air-permeable resin layer, a crosslinkable resin cured material layer, and a laminate of these layers. Particularly, the base material layer / air-permeable resin layer. , Base material layer / air-permeable resin layer / crosslinkable resin cured material layer, crosslinkable resin cured material layer / airpermeable resin layer / base material layer / airpermeable resin layer, crosslinkable resin cured material layer / transparent resistance Layer structure such as gas resin layer / base material layer / gas permeable resin layer / crosslinked resin cured product layer, crosslinkable resin cured product layer / gas permeable resin layer / gas permeable resin layer / crosslinked resin cured product layer is important. In the case of a laminated structure, an anchor coating layer or an adhesive layer can be provided between the layers.

Here, examples of the base material layer include polycarbonate, polymethylmethacrylate, polyethersulfone, polysulfone, polyarylate, amorphous polyolefin, polyparabanic acid resin, and polyamide. The base layer preferably has a heat distortion temperature of 80 ° C. or higher.

The base material layer is obtained by a casting method or an extrusion method, and its thickness is often about 30 μm to 3 mm.

The air-permeable resin constituting the air-permeable resin layer includes, for example, a layer formed of a polymer containing 50 mol% or more of an acrylonitrile component, a vinyl alcohol component or a vinylidene halide component. Polymers having a hydroxyl group such as polyvinyl alcohol or copolymer modified products or graft products thereof, and ethylene-vinyl alcohol copolymer having an ethylene content of 15 to 50 mol% are important.

The air-permeable resin layer is usually formed by a casting method and has an oxygen permeability (measured according to ASTM D-1434-75) of 30 cc / 24 hr · m ² · atm or less, especially 20 cc / 24 hr · m ² ·
Atm or less, more preferably 10 cc / 24 hr · m ² · atm or less. The air-permeable resin layer has a thickness of 1 to 50 μm
In particular, it is suitable to set in the range of 2 to 20 μm. If it is less than 1 μm, the air resistance is insufficient and it is 50 μm.
If it exceeds, it will be against the trend of thinning.

As the crosslinkable resin cured product layer, the resin layer is first prepared.
The crosslinkable resin cured product layer as described in the explanation of (2) is used.

After casting the resin solution for forming the resin layer (2) on the lower layer (1), the amount of residual solvent in the semi-dry coating (2a) is 5 to 100% by weight of the absolute dry coating weight, preferably Is dried to 15 to 80% by weight. If the degree of drying is too small, the semi-dry coating (2a) tends to flow, so a resin layer (2) with a smooth surface cannot be obtained, and the pressure-sensitive adhesive material (3) described below sticks and is difficult to peel off. On the other hand, if the drying is too much, the semi-dry coating (2a) will not be deformed, so the resin layer
The surface smoothness of (2) cannot be obtained, and the intended purpose cannot be achieved.

Then, when the amount of the residual solvent in the semi-dry coating (2a) becomes appropriate, a pressure-bonding material (3) having a surface roughness of 0.5 μm or less is pressed onto the semi-dry coating (2a). Contact with.

Particularly preferred materials for pressure-bonding (3) are biaxially stretched plastics films, especially biaxially stretched polyethylene terephthalate film, biaxially stretched polybutylene terephthalate film, biaxially stretched polyethylene naphthalate film and the like. It is an axially stretched polyester film. This is because the polyester film which does not contain a filler has the property that the surface smoothness is remarkably improved by biaxial stretching. Biaxially oriented polyester film has a surface roughness of 0.15μm or less, 0.05μm
Hereinafter, even films having a thickness of 0.01 μm or less are available, and it is desirable to use such a film as the pressure-bonding material (3).

As the pressure-bonding material (3), other crystalline plastic films having solvent resistance and smoothness (for example, biaxially stretched polypropylene film),
It is also possible to use a polished steel plate belt, a polished steel plate drum, or the like.

After the pressure-bonding material (3) having a surface roughness of 0.5 μm or less is brought into contact with the semi-dry coating (2a) in the pressure-bonded state as described above, the pressure-bonding material (3) is removed and further Either proceed with dry curing, or proceed with dry curing without removing the pressure-bonding material (3) and then remove the pressure-bonding material (3).

As a result, a laminated sheet having a layer structure of the lower layer (1) / resin layer (2) and having an extremely high surface smoothness of the free surface of the resin layer (2) can be obtained. A liquid crystal cell substrate can be manufactured by providing a transparent electrode on the resin layer (2) and further forming an alignment film on the transparent electrode.

For forming the transparent electrode, a vacuum deposition method, a sputtering method, an ion plating method, a metal spraying method, a metal plating method, a chemical vapor deposition method, a spray method, etc. are adopted.
The sputtering method is particularly important. As a material of the transparent electrode, a metal such as Sn, In, Ti, Pb, Tb or an oxide thereof is mainly used, and the layer thickness of the transparent electrode is at least 100 angstrom, and further 20
It is usually 0 angstrom or more.

The optical laminated sheet of the present invention is particularly important as an electrode substrate for manufacturing a liquid crystal display panel, but it can also be used for applications such as retardation plates, polarizing plates, optical disks and optical cards.

[0038]

In the optical laminated sheet of the present invention, the surface smoothness of the free surface of the resin layer (2) located on the surface of the laminated sheet is extremely high. Even when it is used as an electrode substrate, it does not cause a situation in which the screen is very difficult to see due to colors such as purple and green on the display.

[0039]

EXAMPLES The present invention will be further described with reference to examples. Hereinafter, “parts” means parts by weight.

Example 1 A polycarbonate sheet (thickness 90 μm, retardation value 10 nm) as one example of the base material layer (1a) was coated with a water-soluble quaternized ester urethane-based anchor coating agent and dried to a thickness. After providing an anchor coating layer of 1.0 μm in thickness, from above the anchor coating layer,
20 parts of ethylene-vinyl acetate copolymer having an ethylene content of 32 mol%, 45 parts of water, 50 parts of n-propanol, methylolated melamine (Sumitec M manufactured by Sumitomo Chemical Co., Ltd.)
-3) Casting a resin liquid having a composition of 4 parts at a temperature of 110
It was dried by passing through a dryer at ℃. As a result, the air-permeable resin layer (1b) having a thickness of 10 μm was formed.

Then, a phenoxyether resin (manufactured by Tohto Kasei Co., Ltd.) 4 was formed on the air-permeable resin layer (1b).
An applicator of a curable resin composition solution having a composition of 0 part, 40 parts of methyl ethyl ketone, 20 parts of cellosolve acetate, and 40 parts of a 75% solution of an adduct of tolylene diisocyanate and trimethylolpropane (Coronate L manufactured by Nippon Polyurethane Co., Ltd.) Apply using
It was dried at 80 ° C. for 4 minutes and then heated at 130 ° C. for 20 minutes to form a phenoxy ether resin-based crosslinkable resin cured product layer (1c) having a thickness of 8 μm. The layer structure at this time is (1
a) / (1b) / (1c).

Next, an anchor coating layer is provided on the other surface of the polycarbonate sheet (1a) in the same manner as described above, and the air-permeable resin having a thickness of 12 μm is formed on the anchor coating layer in the same manner as described above. Layer (1b) was formed. The layer structure at this time is (1b) / (1a) / (1b) / (1c).

Then, a curable resin composition solution having the same composition as described above was applied from above the air-permeable resin layer (1b) using an applicator and dried at 60 ° C. for 1 minute. The amount of residual solvent in the semi-dry coating (2a) was 30% by weight based on the weight of the absolutely dry coating.

The thus obtained (2a) / (1b) / (1a) /
A biaxially stretched polyethylene terephthalate film having a thickness of 100 μm and a surface roughness of 0.004 μm as an example of the pressure-bonding material (3) on the semi-dried film (2a) of the laminated sheet having the layer structure of (1b) / (1c) While applying an O type manufactured by Teijin Ltd., they were bonded by pressure bonding through a group of rolls under the conditions of a temperature of 80 ° C. and a pressing pressure of 10 kgf / cm ² . Then 3 at room temperature
After standing for 6 hours, the biaxially stretched polyethylene terephthalate film was peeled off from this laminated sheet (the peeling operation was smooth), and the temperature was raised to 125 ° C.
Aging was performed by heating for 0 minutes.

By the above operation, the semi-dry film (2a) is dried and hardened to form a cross-linkable resin hardened material layer (2) having a thickness of 10 μm, and the surface smoothness of its free surface is determined by utilizing the interference of light. It was 0.1 μm or less as measured by a contact type surface roughness meter.

The laminated sheet thus obtained had a retardation value of 18 nm, a visible light transmittance of 89%, and an oxygen transmittance (measured according to ASTM D-1434-75) of 0.5 cc / 24.
hr · m ² · atm, surface pencil hardness is 2H on both sides,
It had no moisture permeability. The total thickness was 132 μm.

Next, a transparent electrode composed of an ITO layer having a thickness of 500 angstrom was directly formed on the surface of the crosslinked resin cured product layer (2) on the smoothed side of the above laminated sheet by a sputtering method. Using this laminated sheet as an electrode substrate, an alignment film was formed and a rubbing treatment was performed, a liquid crystal cell was assembled, and a retardation plate and a polarizing plate were laminated according to a conventional method to produce a liquid crystal display panel. The obtained liquid crystal display panel showed no coloring unevenness in the display and had a performance comparable to that of a liquid crystal display panel using glass as a substrate.

Example 2 In Example 1, the curable resin composition solution was applied onto the air permeation resistant resin layer (1b) of the laminate having the layer structure of (1b) / (1a) / (1b) / (1c). Was applied using an applicator and air-dried at room temperature for 10 minutes. The amount of residual solvent in the semi-dry coating (2a) was 70% by weight based on the weight of the absolutely dry coating.

(2a) / (1b) / (1a) / thus obtained
While applying the same pressure-bonding material (biaxially stretched polyethylene terephthalate film) (3) as in Example 1 on the semi-dried coating (2a) of the laminated sheet having the layer structure of (1b) / (1c), press at room temperature. Under the condition of 50 kgf / cm ^2, the roll groups were pressed together and bonded. After 3 days, the biaxially stretched polyethylene terephthalate film was peeled off from the laminated sheet (the peeling operation was smooth), heated to 125 ° C., and heated at this temperature for 120 minutes for aging.

By the above operation, the semi-dry coating (2a) is dried and cured to form the crosslinked resin cured material layer (2), and the surface smoothness of its free surface is determined by the non-contact surface roughness utilizing light interference. It was 0.1 μm or less as measured by a thermometer.

The laminated sheet thus obtained had a retardation value of 15 nm, a visible light transmittance of 91%, and an oxygen transmittance (measured according to ASTM D-1434-75) of 0.3 cc / 24.
hr · m ² · atm, the pencil hardness of the surface was H on both sides, and it had no moisture permeability.

A liquid crystal display panel was produced using this laminated sheet in the same manner as in Example 1, and the same preferable result as in Example 1 was obtained.

Example 3 An anchor coating layer having a thickness of 0.5 μm was provided on the base material layer (polycarbonate sheet) (1a) in the same manner as in Example 1, and the same procedure as in Example 1 was performed from above the anchor coating layer. Then, an air-permeable resin layer (1b) having a thickness of 8 μm was formed.

Then, a phenoxy ether resin (manufactured by Tohto Kasei Co., Ltd.) 4 was formed on the air-permeable resin layer (1b).
0 part, dioxane 20 parts, cellosolve acetate 40
Part, “Coronate L” 40 parts curable resin composition solution having a composition is applied using an applicator, and 80 ° C.
Dry for 4 minutes, then heat at 130 ° C for 20 minutes,
A phenoxy ether resin-based crosslinkable resin cured product layer (1c) having a thickness of 8 μm was formed. The layer structure at this time is (1a) / (1
b) / (1c).

Next, an anchor coating layer is provided on the other surface of the polycarbonate sheet (1a) in the same manner as described above, and an air-permeable resin having a thickness of 8 μm is formed on the anchor coating layer in the same manner as described above. Layer (1b) was formed. The layer structure at this time is (1b) / (1a) / (1b) / (1c).

Then, a curable resin composition solution having the same composition as described above was applied from above the air-permeable resin layer (1b) using an applicator and dried at 50 ° C. for 6 minutes. The amount of residual solvent in the semi-dry coating (2a) was 23% by weight based on the weight of the absolutely dry coating.

(2a) / (1b) / (1a) / thus obtained
While applying the same pressure-bonding material (biaxially stretched polyethylene terephthalate film) (3) as in Example 1 on the semi-dried coating (2a) of the laminated sheet having the layer structure of (1b) / (1c), press at room temperature. Under the condition of 100 kgf / cm ^2, the roll groups were pressed together and bonded. After 3 days, the biaxially stretched polyethylene terephthalate film was peeled off from the laminated sheet (the peeling operation was smooth), the temperature was raised to 125 ° C., and heating was performed at this temperature for 60 minutes for aging.

By the above operation, the semi-dry coating (2a) is dried and cured to form the crosslinked resin cured material layer (2), and the surface smoothness of its free surface is determined by the non-contact surface roughness utilizing light interference. It was 0.1 μm or less as measured by a thermometer.

The laminated sheet thus obtained had a retardation value of 16 nm, a visible light transmittance of 90%, and an oxygen transmittance (measured according to ASTM D-1434-75) of 0.3 cc / 24.
hr · m ² · atm, the pencil hardness of the surface was H on both sides, and it had no moisture permeability.

A liquid crystal display panel was produced using this laminated sheet in the same manner as in Example 1, and the same preferable result as in Example 1 was obtained.

[0061]

In the optical laminated sheet of the present invention,
For example, even when this is used as an electrode substrate of a liquid crystal cell in which STN liquid crystal is sealed, a situation in which the display is colored purple or green and the screen becomes very difficult to see does not occur.

As the liquid crystal display panel becomes larger year by year,
Although the spread of the STN liquid crystal system is remarkable, the present invention enables display characteristics to be comparable even if a plastics substrate is used instead of the glass substrate for the purpose.

In particular, a laminate of a base material layer / a gas proof resin layer is used as the lower layer (1), and the surface roughness of the free surface as the resin layer (2) is 0.5 on the gas permeable resin layer of the laminate. When forming a crosslinkable resin cured product layer of μm or less, in addition to the achromaticity of the display, air resistance, moisture resistance, non-coloring, high surface hardness,
It comes to satisfy all heat resistance and organic chemical resistance.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location G02F 1/1333 500 7724-2K

Claims (5)

[Claims] 1. A laminated sheet having a resin layer (2) formed by a casting film forming method on the outer layer side, wherein the free surface of said resin layer (2) has a surface roughness of 0.5 μm or less and a retardation value. Is 6
An optical laminated sheet having a visible light transmittance of 0% or less and 60% or more. 2. The optical laminated sheet according to claim 1, wherein the resin layer (2) is a cured crosslinkable resin layer. 3. The optical laminated sheet according to claim 1, which is an electrode substrate for manufacturing a liquid crystal display panel. 4. After casting a resin solution for forming a resin layer (2) on the lower layer (1), the amount of residual solvent in the semi-dry coating (2a) is 5 to 100% by weight of the absolute dry coating weight. The optical layering is characterized in that it is dried until it comes to a contact state, and then the semi-drying film (2a) is contacted with a pressure-bonding material (3) with a surface roughness of 0.5 μm or less in a pressure-bonded state, and then dry curing is carried out. Sheet manufacturing method. 5. The method according to claim 4, wherein the pressure-bonding material (3) is a biaxially stretched plastic film having a surface roughness of 0.15 μm or less.