WO2010134494A2

WO2010134494A2 - Multi-layer polyester film

Info

Publication number: WO2010134494A2
Application number: PCT/JP2010/058299
Authority: WO
Inventors: 祥史上野; 隆信須藤
Original assignee: ソニーケミカル＆インフォメーションデバイス株式会社
Priority date: 2009-05-18
Filing date: 2010-05-17
Publication date: 2010-11-25
Also published as: JP5518374B2; JP2011000708A; WO2010134494A3

Abstract

Disclosed is a transparent electrode sheet which suppresses the precipitation of oligomers without forming a coating layer or an applied layer on the PET surface of the adhesive layer. To avoid heat shrinkage during annealing in the manufacturing process, a touch panel is pre-annealed by heat shrinking the first and second resin films (1, 2) prior to annealing. As a result of having been pre-annealed, when the first and second resin films (1, 2) are heated above glass transition temperature the oligomers within said films are precipitated and disperse. The oligomers, which pass from the resin films (1, 2), along the boundary surface between the films (1, 2) and the adhesive layer (3) and move to the adhesive layer (3), mix with said layer, made from polyethylene containing terephthalic acid and ethylene glycol, and are not precipitated as crystals. Even if the oligomers do not mix with the adhesive layer (3), the light refraction indexes of the oligomers and said layer (3) are almost equal and so the oligomers are not visible.

Description

Multilayer polyester film

The present invention relates to a technical field of a touch panel using a multilayer conductive transparent film, and particularly relates to a technique for suppressing precipitation of oligomers in an adhesive layer.
This application is based on Japanese Patent Application No. 2009-120332 filed on May 18, 2009 in Japan and Japanese Patent Application No. 2009-136530 filed on June 5, 2009. Priority is claimed and is incorporated into this application by reference to these applications.

The transparent conductive electrode used for the touch panel has a three-layer multilayer film in which an adhesive layer made of an acrylic resin is disposed between two film-like PET (polyethylene terephthalate), and further on one PET surface. A hard coat layer is formed, and a transparent electrically conductive thin film made of ITO or the like is formed on the other PET surface to form a touch panel sheet. Usually, this touch panel sheet is subjected to a pre-annealing process for causing thermal shrinkage of PET in advance so that the touch panel sheet is not thermally deformed even if it is annealed in the manufacturing process of the touch panel. When the pre-annealing processing temperature exceeds the glass transition temperature of PET, the diffusion of the oligomer contained in the PET proceeds, and the diffused oligomer is precipitated at the interface between the PET and the adhesive, so that it is not compatible with the adhesive and crystallizes. There was a problem that it turned into cloudy.

In the prior art, priority is given to obtaining adhesion during lamination, and sufficient mechanical strength cannot be obtained, and in order to avoid oligomer precipitation, pre-annealing is performed at an annealing temperature lower than the glass transition temperature of PET. ing. Therefore, the stress of PET is not sufficiently relaxed, and there is a problem that the multilayer film is thermally deformed when annealing is performed in the touch panel manufacturing process.

According to Patent Document 1 described below, oligomers are deposited by forming a coating layer composed of a polyester resin on at least one surface of a laminated polyester film, a compound having an acetylene group and a hydroxyl group in the molecule, and mineral oil. Suppressed.

According to Non-Patent Document 1 described below, oligomer deposition is suppressed by forming a special coating layer on the PET surface.

JP 2006-281498 A WO2004 / 070737 Japanese Patent Publication No. 4-46752 Japanese Patent No. 2667680 JP 2006-56117 A JP 2007-95660

Provide a technology for manufacturing touch panels where the oligomers contained in the resin film are not visible.

In order to solve the above problems, a first resin film made of polyethylene terephthalate, an adhesive layer made of polyester disposed on the surface of the first resin film, and disposed on the surface of the adhesive layer A multilayer polyester film having a second resin film made of polyethylene terephthalate, wherein the first and second resin films are bonded with the adhesive layer, and the multilayer polyester film is heat-treated and used for a touch panel. It is a multilayer polyester film used as a sheet.
In the present invention, the first and second resin films are obtained by polymerizing terephthalic acid and ethylene glycol, and the adhesive layer is a multilayer polyester film made of an adhesive containing terephthalic acid and ethylene glycol. .
This invention is a multilayer polyester film whose glass transition temperature of the said adhesive bond layer is less than 65 degreeC.
The present invention provides a multilayer polyester film according to any one of claims 1 to 3, a first transparent conductive thin film made of indium tin oxide disposed on the back surface of the first resin film, And a protective layer disposed on the surface of the second resin film, wherein at least the multilayer polyester film is heated at a temperature of 140 ° C. or higher and is an upper touch panel sheet used on a pressed surface side of the touch panel. .
The present invention includes an upper touch panel sheet and a lower touch panel sheet having a second transparent conductive thin film, wherein the upper touch panel sheet and the lower touch panel sheet are the first and second transparent conductive thin films. However, when the upper touch panel sheet is pressed so as to face and be separated, the upper touch panel sheet is curved, and the first transparent conductive thin film of the upper touch panel sheet is It is a touch panel in which a current flows in contact with the second transparent conductive thin film of the side touch panel sheet and a position in the contacted surface is required.
The present invention is the touch panel in which the Young's modulus of the adhesive layer of the upper touch panel sheet is 1.5 MPa or more and 3.0 MPa or less.
The present invention is the touch panel in which the adhesive layer of the upper touch panel sheet contains a curing agent that reacts at room temperature.
The present invention includes a touch panel and a liquid crystal display device, and the touch panel is a touch panel with a liquid crystal disposed on the liquid crystal display device.
According to the present invention, an adhesive is placed in contact between the first and second resin films, and the temperature of the adhesive is raised to a temperature of less than 140 ° C. Two resin films are bonded to create a multilayer polyester film, a transparent conductive thin film is disposed on the surface of the first resin film opposite to the surface on which the adhesive is disposed, and the second resin It is a manufacturing method of the upper side touch panel sheet which arrange | positions the said protective layer on the surface on the opposite side to the surface where the said adhesive agent is arrange | positioned of a film, Comprising: It has the heating process which heat-processes the said multilayer polyester film at the temperature of 140 degreeC or more. It is a manufacturing method of an upper side touch panel sheet.

In addition, this heating process is after a multilayer polyester film is made until it arrange | positions a transparent conductive thin film on the back surface of a 1st resin film, or a transparent conductive thin film on the back surface of a 1st resin film Between the time when the protective layer is placed on the surface of the second resin film and the time after the protective layer is placed on the surface of the second resin film.
Here, the adhesive represents an adhesive layer and an adhesive film described later.

The adhesive layer of the upper touch panel sheet of the present invention has an adhesive strength for bonding PET to each other, and the oligomer in the adhesive layer can be formed without forming a coating layer or a coating layer on the PET surface on the adhesive layer side. Even if it is not mixed with the adhesive layer and is not crystallized or not mixed, the refractive index of the light of the oligomer and the adhesive layer is almost the same, so it is not visually observed, so the touch panel sheet manufacturing process and cost can be reduced. .

FIG. 1 is a cross-sectional view of the first resin film. FIG. 2 is a cross-sectional view of the first resin film and the adhesive layer disposed on the first resin film. FIG. 3 is a cross-sectional view of the multilayer polyester film of the present invention. FIG. 4 is a cross-sectional view of the touch panel sheet of the present invention. FIG. 5 is a cross-sectional view of the upper touch panel sheet of the present invention. FIG. 6 is a cross-sectional view of the touch panel with a liquid crystal display according to the present invention. FIG. 7 is a view for explaining a method for producing the multilayer polyester film of the present invention using the first and second resin film rolls and the adhesive film roll.

1 is a first resin film made of PET (polyethylene terephthalate), which is a process object.

When a solution containing a polyester-based adhesive containing terephthalic acid and ethylene glycol is applied to the surface of the first resin film 1, and the temperature of the solution is raised to the evaporation temperature of the solvent (about 110 ° C. to 120 ° C.), The solvent evaporates, the adhesive layer 3 is formed on the surface of the first resin film 1, and the surface of the first resin film 1 and the back surface of the adhesive layer 3 are bonded (FIG. 2).

When the adhesive layer 3 formed on the first resin film 1 is heated to about 80 ° C. and the back surface of the second resin film 2 made of PET is bonded to the surface of the adhesive layer 3, The surface of the adhesive layer 3 and the second resin film 2 are bonded to form a multilayer polyester film 5 (FIG. 3).

When the first transparent conductive thin film 7 made of ITO (indium tin oxide) is formed on the back surface of the first resin film 1 of the multilayer polyester film 5 by sputtering or the like, the multilayer transparent conductive sheet 10 is formed. (FIG. 4).

In addition, the transparent conductive thin film formed into a film is not limited to ITO, What is necessary is just transparent electrodes, such as a tin oxide and a zinc oxide.

The surface of the second resin film 2 of the multilayer transparent conductive sheet 10 is coated with a resin paint containing an inorganic filler such as silicon nitride, alumina, silica, titanium oxide, etc., and the temperature of the solution rises above the evaporation temperature of the solvent. When the paint is cured, the hard coat layer 8 is formed as a protective layer on the surface of the second resin film 2, and the upper touch panel sheet 15 is formed (FIG. 5).

The order of laminating the first and

second resin films

1 and 2 through the adhesive layer 3 and the timing for forming the first transparent conductive thin film 7 and the hard coat layer 8 are within the scope of the object of the present invention. Can be selected arbitrarily.

<Heat treatment>
When the upper touch panel sheet 15 is subjected to an annealing process for drying at a temperature of about 140 ° C. or higher in the touch panel manufacturing process, the first and

second resin films

1 and 2 of the upper touch panel sheet 15 are thermally shrunk to the first. The wiring printed on the screen on the transparent conductive thin film 7 is distorted. In order to prevent thermal shrinkage during the annealing process, a pre-annealing process is performed in which the upper touch panel sheet 15 is heated in advance to heat-shrink the first and

second resin films

1 and 2 before the wiring is printed.

When the upper touch panel sheet 15 is heated to 140 ° C. or higher by the pre-annealing process, it exceeds 110 ° C., which is the glass transition temperature of the first and

second resin films

1 and 2. 2, the diffusion of the oligomer contained in 2 proceeds.

The oligomer moves from the first and

second resin films

1 and 2 to the adhesive layer 3 through the interface between the first and

second resin films

1 and 2 and the adhesive layer 3. Crystallization does not proceed by mixing with polyester which is a component of the agent layer 3. In addition, since the oligomer and the adhesive layer 3 are both polyester components, the refractive index of light is substantially equal, and even if it is crystallized, it is difficult to visually observe the portion.

The adhesive strength of the adhesive layer 3 bonded to the first and

second resin films

1 and 2 does not decrease even at a temperature of 140 ° C. or higher.

The multilayer polyester film 5 is more flexible than a single PET film having the same thickness as the total thickness of the first and

second resin films

1 and 2 and the adhesive layer 3.

<Touch panel>
The touch panel 50 includes the upper touch panel sheet 15 and the multilayer transparent conductive sheet 10. Here, the multilayer transparent conductive sheet 10 is used as the lower touch panel sheet 10a.

The upper touch panel sheet 15 and the lower touch panel sheet 10a are separated so that the first transparent conductive thin film 7 of the upper touch panel sheet 15 and the second transparent conductive thin film 7a of the lower touch panel sheet 10a face each other. Arranged.

FIG. 6 shows a liquid crystal touch panel 55 in which a touch panel 50 is arranged on the liquid crystal display device 11.

When a voltage is applied to the first and second transparent conductive

thin films

7 and 7a and the hard coat layer 8 of the upper touch panel sheet 15 is pressed with a pen or a finger, the upper touch panel sheet 15 is bent and the upper touch panel sheet. The first transparent conductive thin film 7 of 15 and the second transparent conductive thin film 7a of the lower touch panel sheet 10a come into contact with each other, a current flows, and the position in the plane of the contact point is obtained.

Since the upper touch panel sheet 15 has flexibility and impact resistance even when pressed, the upper touch panel sheet 15 bends even when pressed at the edge of the screen window of the upper touch panel sheet 15, and the first transparent conductive material of the upper touch panel sheet 15. When the conductive thin film 7 and the second transparent conductive thin film 7a of the lower touch panel sheet 10a come into contact with each other, a current flows and the position in the surface is obtained.

<Method for producing multilayer polyester film roll>
The code | symbol 20 of FIG. 7 is a multilayer polyester roll manufacturing apparatus, the 1st, 2nd resin film rolls 21 and 22, the adhesive bond layer application part 23, the 1st, 2nd bonding rolls 24 and 25, And a winding device 26.

The first and second resin film rolls 21 and 22 are wound with the first and

second resin films

31 and 32 made of PET, and the polyester containing terephthalic acid and ethylene glycol from the adhesive layer coating portion 23. A solution containing a system adhesive is applied onto the first resin film 31 and the solvent is evaporated to form the adhesive layer 33.

The first and second resin film rolls 21 and 22 and the adhesive layer application part 23 are arranged in front of the first and second bonding rolls 24 and 25, and the winding device 26 includes the first and second It arrange | positions in the back | latter stage of the two bonding rolls 24 and 25. FIG.

When the first and

second resin films

31 and 32 are pulled out from the first and second resin film rolls 21 and 22, and the adhesive layer 33 is applied and formed on the first resin film 31 by the adhesive layer application part 23. The first and second laminating rolls 24 and 25 are passed between the first and second bonding rolls 24 and 25 so as to be wound around the winding device 26.

The first resin film roll 21, the adhesive layer application part 23, and the second resin film roll 22 are arranged in this order from the bottom, and the tips of the first and

second resin films

31 and 32 are arranged. When the take-up device 26 is held and the take-up device 26 is operated, the first and

second resin films

31 and 32 are pulled out from the first and second resin film rolls 21 and 22, and the adhesive layer 33. Is applied and formed on the first resin film 31 from the adhesive layer application part 23.

The drawn first and

second resin films

31 and 32 are provided between the first and second laminating rolls 24 and 25 and the adhesive layer 33 formed on the first resin film 31 is interposed between them. And sandwiched between them. The first and

second resin films

31 and 32 bonded together through the adhesive layer 33 become a multilayer polyester film 35. When the film is wound around the winding device 26, a multilayer polyester film roll 39 is obtained.

<Example>
In Examples 1 to 6, the adhesive layer 3 was formed by changing the compounding ratio of the polyester resins A, B, and C having a glass transition temperature of 5 ° C., 65 ° C., and −20 ° C. and the curing agent, and the adhesive layer 3 Young's modulus and glass transition temperature (Tg) were measured. Also, the first and

second resin films

1 and 2 are bonded to each other through the adhesive layer 3 to create a multilayer polyester film 5, and the multilayer polyester film 5 is pre-annealed at a temperature of 140 ° C. or higher. An evaluation of the occurrence of oligomers in the adhesive layer and a 180 ° peel strength test were performed to examine the adhesive strength and impact resistance between the adhesive layer 3 and the first and

second resin films

1 and 2.
In addition, the dynamic viscoelasticity measuring apparatus (RSA3 made by a TA instrument company) was used for the measuring method of Young's modulus.
The glass transition temperature was measured from the tan delta peak value given by a dynamic viscoelasticity measuring device (RSA manufactured by TA Instruments).

In Comparative Example 1 to Comparative Example 4, the adhesive layer 3 is formed by changing the compounding ratio of the polyester resin B, the acrylic resin, and the photoinitiator, and the first and second resin films 1 are interposed via the adhesive layer 3. 2 and after pre-annealing at a temperature of 140 ° C. or higher, the generation of oligomers in the adhesive layer is evaluated, a 180 degree peel strength test is performed, and the adhesive layer 3 and the first and second resins The adhesive strength and impact resistance with the

films

1 and 2 were examined.

Table 1 showing the relationship between the Young's modulus and glass transition temperature of the adhesive layer 3 relative to the adhesive layer 3, the investigation of the occurrence of oligomers in the adhesive layer, the adhesive strength of the multilayer polyester film 5, and the impact resistance was obtained.

<Oligomer generation evaluation>
The size of the oligomer generated in the adhesive layer 3 was observed at a magnification of 1000 using a digital microscope (manufactured by KEYENCE). When the largest of the generated oligomers is observed with a maximum diameter of less than 5 μm, the largest one of the generated oligomers with a maximum diameter of 5 μm or more is observed as ◯ (preferred) X (not preferable).

<Adhesive strength>
When the 180 degree peel strength was 1 N / cm or more, A (preferred) was designated, and when the 180 degree peel strength was less than 1 N / cm, B (not preferred) was designated.

<Impact resistance>
C (preferred) when the peel state in the 180 degree peel strength test is interface fracture, cohesive fracture, or material breakage, and D (not preferred) when the peel state after the 180 degree peel strength test is jerky peel .

The evaluation of the generation of oligomers in Examples 1 to 6 is preferable. The oligomer is mixed with polyester as a component of the adhesive layer 3 so that crystallization does not proceed, or both the oligomer and the adhesive layer 3 are polyester. Therefore, even if it is crystallized, it is difficult to visually check that portion.

The Young's modulus of the adhesive layer 3 of Example 2 is larger than the Young's modulus of the adhesive layer 3 of Example 1 due to the addition of the curing agent isocyanate. Thus, even if a hardening | curing agent is added, if Young's modulus is the range of 1.5 MPa or more and 3.0 MPa or less, both adhesive strength and impact resistance will be compatible.

Although the glass transition temperature of the adhesive layer 3 of Example 5 is lower than that of the other examples, the adhesive strength and the impact resistance are compatible.

In Example 6, the impact resistance is jerky peeling, and the impact resistance of the adhesive layer 3 is weak compared to the impact resistance of Examples 1 to 5, so that it can be used as the upper touch panel sheet 15. Although it is not possible, since the evaluation of oligomer generation and the adhesive strength are preferable, it can be used as the lower touch panel sheet 10a.

In Example 6, the evaluation of oligomer generation is preferable, and the Young's modulus exceeds 3.0 MPa, which is larger than Examples 1 to 5, but is used as the lower touch panel sheet 10a because the adhesive strength is maintained. You can see that you can.

In Comparative Example 2, although a polyester resin is used for the adhesive layer 3, the glass transition temperature is higher than that in Examples 1 to 6, so that the adhesive strength and impact resistance are not preferable.

Although the Young's modulus and glass transition temperature of the adhesive layer of Comparative Example 3 are within the preferred ranges of the Young's modulus and glass transition temperature of Examples 1 to 5, the maximum diameter of the generated oligomers is the largest. Since the thing of 5 micrometers or more was observed, since it may be visually observed, it is not preferable.

According to the examples and comparative examples, the Young's modulus of the adhesive layer 3 of the upper touch panel sheet 15 is preferably in the range of 1.5 MPa to 3.0 MPa, and the adhesive layers of the upper touch panel sheet 15 and the lower touch panel sheet 10a. The glass transition temperature of 3 indicates that a range of less than 65 ° C. is preferable.

1,31 1st resin film, 2,32 2nd resin film, 3,33 adhesive layer, 5,35 multilayer polyester film, 7 transparent conductive thin film, 8 hard coat layer, 10 multilayer transparent conductive sheet, 10a Lower touch panel sheet, 11 Liquid crystal display device, 15 Upper touch panel sheet, 20 Multi-layer polyester roll manufacturing device, 21 First resin film roll, 22 Second resin film roll, 23 Adhesive layer application section, 24 First Laminating roll, 25, 2nd laminating roll, 26 winding device, 39 multilayer polyester film roll, 50 touch panel, 55 touch panel with liquid crystal

Claims

A first resin film made of polyethylene terephthalate;
An adhesive layer made of polyester disposed on the surface of the first resin film;
A multilayer polyester film having a second resin film made of polyethylene terephthalate disposed on the surface of the adhesive layer,
The first and second resin films are bonded with the adhesive layer,
The multilayer polyester film is a multilayer polyester film that is heated and used for a touch panel.
The multilayer polyester film according to claim 1, wherein the first and second resin films are obtained by polymerizing terephthalic acid and ethylene glycol, and the adhesive layer is made of an adhesive containing terephthalic acid and ethylene glycol.
The multilayer polyester film according to any one of claims 1 and 2, wherein a glass transition temperature of the adhesive layer is less than 65 ° C.
The multilayer polyester film according to any one of claims 1 to 3, wherein a glass transition temperature of the adhesive layer is -20 ° C or higher and 35 ° C or lower.
The multilayer polyester film according to any one of claims 1 to 4, wherein a Young's modulus of the adhesive layer is 1.5 MPa or more and 3.0 MPa or less.
The multilayer polyester film according to any one of claims 1 to 5,
A first transparent conductive thin film made of indium tin oxide disposed on the back surface of the first resin film;
A protective layer disposed on the surface of the second resin film,
At least the multilayer polyester film is heated at a temperature of 140 ° C. or higher, and is an upper touch panel sheet used on the surface side to be pressed of the touch panel.
The upper touch panel sheet according to claim 6,
A lower touch panel sheet having a second transparent conductive thin film,
The upper touch panel sheet and the lower touch panel sheet are arranged so as to face each other so that the first and second transparent conductive thin films face each other, and when the upper touch panel sheet is pressed, The touch panel sheet is curved, the first transparent conductive thin film of the upper touch panel sheet is in contact with the second transparent conductive thin film of the lower touch panel sheet, current flows, A touch panel that requires a position.
The touch panel according to claim 7, wherein a Young's modulus of the adhesive layer of the upper touch panel sheet is 1.5 MPa or more and 3.0 MPa or less.
The touch panel according to claim 7 or 8, wherein the adhesive layer of the upper touch panel sheet contains a curing agent that reacts at room temperature.
10. A touch panel with a liquid crystal, comprising: the touch panel according to claim 7; and a liquid crystal display device, wherein the touch panel is disposed on the liquid crystal display device.
An adhesive is placed in contact between the first and second resin films, and the temperature of the adhesive is raised to a temperature lower than 140 ° C., and the first and second resin films are interposed via the adhesive. To make a multilayer polyester film,
A transparent conductive thin film is disposed on the surface of the first resin film opposite to the surface on which the adhesive is disposed;
In the method of manufacturing the upper touch panel sheet, the protective layer is disposed on the surface opposite to the surface on which the adhesive of the second resin film is disposed,
The manufacturing method of the upper side touch panel sheet | seat which has a heating process which heat-processes the said multilayer polyester film at the temperature of 140 degreeC or more.