JP5518374B2 - Adhesive layer for suppressing oligomer precipitation of laminated laminated PET film - Google Patents

Description

  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.

  A transparent conductive electrode used for a touch panel is composed of a three-layer laminated film in which an adhesive layer made of an acrylic resin is disposed between two film-like PET (polyethylene terephthalate), and a hard surface is formed on one PET surface. A coating layer is formed, and a transparent electroconductive thin film made of ITO or the like is formed on the other PET surface to form a multilayer film. Usually, this multilayer film is pre-annealed in advance to cause thermal shrinkage of PET so that it will not be thermally deformed even if it is annealed in the touch panel manufacturing process. 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 pre-annealing is performed at an annealing temperature lower than the glass transition temperature of PET in order to avoid oligomer precipitation. 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 JP2007-95660 “Surface protective material for touch panel E-MASK / TP200”, Nitto Denko Technical Report, 2008, p. 53

  Provided is a technique for manufacturing a touch panel in which an oligomer contained in a resin film is not visually observed.

In order to solve the above problems, a first resin film made of polyethylene terephthalate, an adhesive layer made of polyester containing terephthalic acid and ethylene glycol, disposed on the surface of the first resin film, and the adhesive a multilayer polyester film and a second resin film made of polyethylene terephthalate, which is disposed on the surface of the adhesive layer, said first, second resin film are bonded with the adhesive layer, the adhesive the glass transition temperature of the layer is in the range of -20 ° C. or higher 35 ° C. or less, wherein the multilayer polyester film, is pressurized heat is a multilayer polyester film used in the touch panel.
The present invention includes a multi-layer polyester film, a first transparent conductive thin film made of arranged indium tin oxide on the back surface of the first resin film, disposed on a surface of the second resin film And a protective layer, 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 side of the touch panel to be pressed.
The present invention includes an upper touch panel sheet and a lower touch panel sheet having a second transparent conductive thin film, and 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 spaced apart, the upper touch panel sheet is curved, and the first transparent conductive thin film of the upper touch panel sheet is the lower 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.
In the present invention, an adhesive having a glass transition temperature of −20 ° C. or more and 35 ° C. or less is formed between polyesters containing terephthalic acid and ethylene glycol between first and second resin films made of polyethylene terephthalate. The first and second resin films are bonded to each other by raising the temperature of the adhesive to a temperature of less than 140 ° C. and bonding the first and second resin films through the adhesive, wherein the adhesive is disposed face the transparent conductive thin film on a surface opposite disposed, the second holding on a surface thereof opposite to the adhesive is disposed face of the resin film Mamoruso of resin film A method for producing an upper touch panel sheet, comprising a heating step of heat-treating the multilayer polyester film at a temperature of 140 ° C. or higher. It is.

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. .

Cross section of the first resin film Sectional drawing of the adhesive layer arrange | positioned on the 1st resin film and the 1st resin film Sectional view of the multilayer polyester film of the present invention Cross-sectional view of the touch panel sheet of the present invention Sectional drawing of the upper side touch panel sheet of this invention Sectional drawing of the touchscreen with a liquid crystal display of the present invention The figure for demonstrating the manufacturing method of the multilayer polyester film of this invention by the 1st, 2nd resin film roll and adhesive film roll

  Reference numeral 1 in FIG. 1 denotes a first resin film made of PET (polyethylene terephthalate), which is a process object.

  When a solution containing an adhesive made of polyester 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 a temperature higher than the evaporation temperature of the solvent (about 110 ° C. to 120 ° C.) The solvent evaporates, and 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 the multilayer polyester film 5 of the present invention (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 touch panel sheet 15 of the present invention 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 contracted 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 more by the pre-annealing process, the upper touch panel sheet 15 exceeds 110 ° C. which is the glass transition temperature of the first and second resin films 1 and 2. 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.

  Even if the adhesive layer 3 has a temperature of 140 ° C. or higher, the adhesive strength to be bonded to the first and second resin films 1 and 2 does not decrease.

  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 disposed 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 of the present invention 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, so The transparent 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 to flow current, and the position in the plane 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 an adhesive consisting of 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 winding device 26 is held and 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. Sandwiched between the two. 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 Example 1 to Example 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 a curing agent, 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 among 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, ○ (preferred) is marked as ○ (preferred) when the maximum of the generated oligomers with a maximum diameter of 5 μm or more is observed 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 that 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 it is the range of the Young's modulus of this invention, 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 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, evaluation of oligomer generation is preferable, and although Young's modulus is larger than those in Examples 1 to 5, it can be used as the lower touch panel sheet 10a because the adhesive strength is maintained. .

  In Comparative Example 2, although a polyester resin is used for the adhesive layer 3, the glass transition temperature is higher than those in Examples 1 to 6, and therefore, 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 above 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 layer 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.

  DESCRIPTION OF SYMBOLS 1, 31 ... First resin film 2, 32 ... Second resin film 3, 33 ... Adhesive layer 5, 35 ... Multi-layer 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 …… Multilayer polyester roll manufacturing device 21 …… First resin film roll 22 …… Second resin Film roll 23 …… Adhesive layer application part 24 …… First bonding roll 25 …… Second bonding roll 26 …… Rewinder 39 …… Multi-layer polyester film roll 50 …… Touch panel 55 …… With liquid crystal Touch panel

Claims (7)

A first resin film made of polyethylene terephthalate;
An adhesive layer disposed on the surface of the first resin film and made of polyester containing terephthalic acid and ethylene glycol ;
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 glass transition temperature of the adhesive layer is in the range of −20 ° C. or more and 35 ° C. or less,
The multilayer polyester film is a multilayer polyester film that is heated and used for a touch panel. A multilayer polyester film according to claim 1 ;
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 2 ,
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 3 , wherein 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. Wherein the adhesive layer of the upper panel sheet, according to claim 3 or any panel of one of claims 4 contains a curing agent which reacts at room temperature. A touch panel according to one of claims 3 to 5, a liquid crystal display device, the touch panel LCD with a touch panel disposed on the liquid crystal display device. Between the first and second resin films made of polyethylene terephthalate, made of polyester containing terephthalic acid and ethylene glycol, and positioned in contact with an adhesive having a glass transition temperature in the range of −20 ° C. to 35 ° C. The adhesive is heated to a temperature of less than 140 ° C., and the first and second resin films are bonded via the adhesive 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;
A method of manufacturing a top touch panel sheet to place the coercive Mamoruso on the opposite side to the adhesive is disposed face of the second resin film,
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.

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