JP5732436B2 - Method for producing pressure-sensitive adhesive sheet and method for producing laminate for touch panel - Google Patents

Description

  The present invention relates to a method for producing a pressure-sensitive adhesive sheet used for a laminate for a touch panel and a method for producing a laminate for a touch panel by sticking members using the pressure-sensitive adhesive sheet obtained by this method.

  At present, the touch panel units mainly used are roughly classified into a resistance film type touch panel and a capacitance type touch panel, both of which are laminates of various materials. System adhesive is used. Since the touch panel unit is disposed on the outermost surface of the screen, the acrylic pressure-sensitive adhesive to be used is required to have high transparency, and further, characteristics such as high heat resistance and moisture heat resistance are required. Specifically, since the touch panel unit, which is a laminate of various materials, is disposed on the outermost surface of the touch panel device, whitening may occur due to the ingress of moisture from the outside. There is a problem that poor appearance occurs due to foaming by entraining and foaming by outgas generated from the material to be laminated.

  Moreover, in the resistive film type touch panel which has been the mainstream of touch panels so far, various adhesives have been used for attaching polycarbonate (PC) or in-mold film (IMD).

  However, as a characteristic of the PC material, outgas is generated under high temperature conditions, and since PC easily passes moisture, foaming occurs under heat resistant conditions, and the whitening phenomenon of the adhesive layer due to moisture inflow under wet heat conditions is suppressed. There is also the problem that it is difficult. Furthermore, since the IMD has a step of submicron order, there is also a problem that the pressure-sensitive adhesive cannot follow the step and bubbles are involved.

  Conventionally, the above problems have been solved by adding an acid component to the pressure-sensitive adhesive. In other words, the acid component has the function of dispersing the mixed water and preventing it from being deposited, and the water that has entered the pressure-sensitive adhesive layer is dispersed and not precipitated in the pressure-sensitive adhesive layer by the dispersion force of the acid component. The pressure-sensitive adhesive layer was prevented from being whitened and also formed with hydrogen bonds, so the generation of bubbles in heat-resistant foaming was suppressed by the high cohesive force due to the hydrogen bonds.

  Recently, with the enhancement of functions such as multi-touch, capacitive touch panels are becoming the mainstream instead of resistive touch panels. In this capacitive touch panel, the characteristics required for the resistive touch panel are of course necessary, but in addition, because the adhesive is in direct contact with the conductive layer forming the wiring, The property that the adhesive does not change the properties of the conductive layer is required. The conductive layer is made of a metal or metal oxide such as indium tin oxide (ITO), which causes corrosion due to contact with an acid and increases its resistance value. Means for securing properties such as heat resistance and wet heat resistance using components cannot be used.

  Regarding the corrosion of such transparent electrodes made of metal such as ITO or metal oxide, Patent Document 1 (Japanese Patent Laid-Open No. 2010-77287) discloses a polymer mainly composed of alkoxyalkyl acrylate. In this Patent Document 1, it is disclosed to use an alkoxyalkyl acrylate polymer having a weight average molecular weight of 400,000 to 1.6 million and not using a carboxyl group-containing monomer.

  By not containing a carboxyl group-containing monomer in this way, the corrosion of transparent electrodes made of metals such as ITO or metal oxides is improved to some extent, but sufficient effects are obtained with respect to performance such as wet heat whitening and heat resistant foaming. Not got. Furthermore, workability is not sufficient.

  Furthermore, since the weight average molecular weight of the polymer disclosed in Patent Document 1 is as large as 400,000 to 1.6 million, the viscosity of the polymer solution increases when the solid content increases when this is dissolved in a solvent to prepare a coating solution. Is too high. In touch panel applications, particularly capacitive touch panel applications, it is necessary to form a thick adhesive layer in order to adhere a surface support and a conductive film such as ITO, but the weight average molecular weight is 400,000 to Since a coating liquid with a high solid content cannot be prepared using 1.6 million alkoxyalkyl acrylate polymers, it is necessary to prepare a coating liquid with a low solid content and apply repeatedly. There is a problem that it is difficult to form an adhesive layer having a thickness required for coating.

JP 2010-77287 A

  The present invention is excellent in coatability, and has good cutting properties when cutting into a desired shape, and does not cause a string drawing phenomenon from the cut end, and conforms to the shape when bonding is performed under heating. It aims at providing the method of manufacturing an adhesive film with good property.

  Furthermore, the present invention is an adhesive sheet which is excellent in coating property and has a good cutting property when it is cut into a desired shape, and does not cause a string drawing phenomenon from the cut end portion. An object of the present invention is to provide a method for producing a laminate for a touch panel using a pressure-sensitive adhesive sheet having good form following characteristics.

The method for producing the pressure-sensitive adhesive sheet of the present invention includes the following components (a-1) to (a-4):
(a-1) alkyl (meth) acrylate having 8 to 18 carbon atoms in the alkyl group
80 to 93% by weight ,
(a-2) 1 to 5% by weight of a hydroxyl group-containing monomer,
(a-3) 6-9% by weight of nitrogen-containing monomer and
(a-4) Other monomers containing 0 to 13% by weight of acrylic acid ester (the total of the above components (a-1) to (a-4) is 100% by weight) are copolymerized in the presence of an organic solvent. Forming an acrylic polymer (A) solution having a weight average molecular weight of substantially 50,000 or more and less than 400,000, which has substantially no acidic group.
The isocyanate-based crosslinking agent (B) is used in the acrylic polymer (A) solution in an amount within the range of 0.1 to 30 parts by weight with respect to 100 parts by weight of the solid content in the acrylic polymer (A) solution. the crosslinked structure is formed Te, the isocyanate the acrylic polymer cross-linked structure is formed by a crosslinking agent (a) solution was cast, with the production of pressure-sensitive adhesive sheet to remove the solvent and formed from the PSA sheet A pressure-sensitive adhesive sheet test piece having a thickness of 200 μm and a width of 10 mm is formed by forming a pseudo-crosslinked structure so that the breaking distance of the tensile test at each temperature is gradually shortened as the measurement temperature is increased at a speed of 100 mm / min. It is said.

In the present invention, the pressure-sensitive adhesive sheet has a breaking distance at 23 ° C. in the range of 150 to 50 mm, a breaking distance at 60 ° C. in the range of 143 to 40 mm, and a breaking distance at 80 ° C. in the range of 136 to 30 mm. In addition, it is preferable to form a pseudo-crosslinked structure so that the breaking distances at 23 ° C., 60 ° C., and 80 ° C. have a relationship represented by the following formula (1).
23 ° C. breaking distance> 60 ° C. breaking distance> 80 ° C. breaking distance (1)
The breaking distance at 60 ° C. of the pressure-sensitive adhesive sheet is in the range of 50 to 95% of the breaking distance at 23 ° C., and the breaking distance of 80 ° C. is in the range of 50 to 95% of the breaking distance at 60 ° C. Preferably there is.

The laminate for a touch panel of the present invention has the following components (a-1) to (a-4):
(a-1) alkyl (meth) acrylate having 8 to 18 carbon atoms in the alkyl group
80 to 93% by weight ,
(a-2) 1 to 5% by weight of a hydroxyl group-containing monomer,
(a-3) 6-9% by weight of nitrogen-containing monomer and
(a-4) Other monomers containing 0 to 13% by weight of acrylic acid ester (the total of the above components (a-1) to (a-4) is 100% by weight) are copolymerized in the presence of an organic solvent. Forming an acrylic polymer (A) solution having a weight average molecular weight of substantially 50,000 or more and less than 400,000, which has substantially no acidic group.
The isocyanate-based crosslinking agent (B) is used in the acrylic polymer (A) solution in an amount within the range of 0.1 to 30 parts by weight with respect to 100 parts by weight of the solid content in the acrylic polymer (A) solution. the crosslinked structure is formed Te, the isocyanate the acrylic polymer cross-linked structure is formed by a crosslinking agent (a) solution was cast, with the production of pressure-sensitive adhesive sheet to remove the solvent and formed from the PSA sheet A pressure-sensitive adhesive sheet in which a pseudo-crosslinked structure is formed so that the breaking distance of a tensile test at each temperature under a speed condition of 100 mm / min for a pressure-sensitive adhesive sheet test piece having a thickness of 200 μm and a width of 10 mm gradually decreases as the measurement temperature increases. It is characterized by sticking a transparent substrate and an electrode.

In the manufacturing method of the laminated body for touchscreens of this invention, the breaking distance in 23 degreeC of the said adhesive sheet exists in the range of 150-50 mm, and the breaking distance in 80 degreeC is in the range whose breaking distance in 60 degreeC is 143-40 mm. It is preferable that the pseudo-crosslinked structure is formed so that the breaking distance at 23 ° C., 60 ° C. and 80 ° C. has a relationship represented by the following formula (1) while being in the range of 136 to 30 mm.
23 ° C. breaking distance> 60 ° C. breaking distance> 80 ° C. breaking distance (1)
Moreover, in the manufacturing method of the laminated body for touchscreens of this invention, the breaking distance in 60 degreeC exists in the range of 50 to 95% of the breaking distance of 23 degreeC, and the breaking distance of 80 degreeC is a breaking distance of 60 degreeC. It is preferable that it exists in 30 to 95% of range.

  In the manufacturing method of the laminated body for touchscreens of this invention, it is preferable that the said adhesive sheet is an adhesive sheet for electrostatic capacitance type touch panels which contacts a metal or a metal oxide directly.

  Since the pressure-sensitive adhesive sheet obtained by the method for producing a pressure-sensitive adhesive sheet of the present invention does not substantially contain an acid component, deterioration due to corrosion of a metal or metal oxide such as silver, ITO, ATO, or tin oxide. Can be effectively suppressed.

  Furthermore, since the weight average molecular weight (Mw) of the acrylic polymer used for the pressure-sensitive adhesive sheet obtained by the method for producing a pressure-sensitive adhesive sheet of the present invention is 50,000 or more and less than 40, the solid content is kept at a high concentration in the solvent. It is possible to apply a sufficient thickness in a single coating process.

  In the pressure-sensitive adhesive obtained by the method for producing a pressure-sensitive adhesive sheet of the present invention, the pressure-sensitive adhesive constituting the pressure-sensitive adhesive sheet has, for example, a structure represented by —OH caused by a hydroxyl group-containing monomer and, for example, R caused by a nitrogen-containing monomer. It is presumed that a structure represented by —N—R (R is an alkyl group or a hydrogen atom) coexists, and a pseudo-crosslinked structure similar to a hydrogen bond is formed between these structures at low temperatures. On the other hand, the cohesive force due to such pseudo-crosslinking is weak in a high temperature state such as during heat sticking. Therefore, the breaking distance (SS curve) measured at different temperatures becomes longer because the strength due to pseudo-crosslinking is compensated at low temperatures, but becomes shorter because the strength compensation due to pseudo-crosslinking decreases at higher temperatures. .

  For this reason, when it sticks under heating, the adhesive which comprises this adhesive tape becomes very soft, shows favorable form followability, and a bubble is not formed in a frame printing part. On the contrary, when the adhesive tape is cut into a predetermined shape, since this cutting is performed at room temperature, a considerable amount of pseudo-crosslinking is formed in the adhesive constituting the adhesive tape. It is quite hard. For this reason, even when the cutter blade and the adhesive come into contact with each other, the adhesive does not adhere to the cutter blade, and the adhesive adheres to the cutter blade and the adhesive is stretched. Phenomenon (string drawing phenomenon) hardly occurs.

FIG. 1 is a cross-sectional view schematically showing an example of a touch panel unit in a resistive film type touch panel incorporating the laminate for a touch panel of the present invention. FIG. 2 is a cross-sectional view schematically showing an example of a touch panel unit in a capacitive touch panel incorporating the laminate for a touch panel of the present invention. FIG. 3 is a cross-sectional view schematically showing an example of the configuration of the end portion of the capacitive touch panel. FIG. 4 is a cross-sectional view schematically showing the adhesive state of the adhesive sheet to the frame print portion formed at the end of the touch panel. FIG. 5 is a cross-sectional view for explaining the state of foaming that occurs in the laminate for a touch panel. FIG. 6 is a cross-sectional view for explaining the occurrence of a whitening phenomenon that occurs in the laminate for a touch panel. FIG. 7 is an SS curve showing the breaking distances of 23 ° C., 60 ° C. and 80 ° C. of the pressure-sensitive adhesive sheet produced in Example 1. FIG. 8 is an SS curve showing the break distances of the pressure-sensitive adhesive sheet produced in Comparative Example 2 at 23 ° C., 60 ° C., and 80 ° C.

Next, the manufacturing method of the adhesive sheet of this invention and the manufacturing method of the laminated body for touchscreens are demonstrated concretely.
The method for producing the pressure-sensitive adhesive sheet of the present invention comprises a specific amount of (a-1) an alkyl group having 8 to 18 carbon atoms (meth) acrylate, (a-2) a hydroxyl group-containing monomer, and (a-3) a nitrogen-containing monomer. And, if necessary, (a-4) an acrylic polymer (A) is obtained by copolymerizing other acrylic acid esters in the presence of an organic reaction solvent, and this acrylic polymer (A) is converted into a specific amount of isocyanate-based polymer. This is a method for producing a pressure-sensitive adhesive sheet by cross-linking with a cross-linking agent (B) to obtain a liquid for pressure-sensitive adhesive, and then cultivating and curing the liquid. And in the manufacturing method of this invention, when it consists of an acryl-type polymer (A) and an isocyanate crosslinking agent (B), a tensile test was done at a speed | rate of 100 mm / min to the adhesive layer of thickness 200 micrometers and width 10mm. A weak intermolecular cross-linked structure between the cross-linked structure of the isocyanate cross-linking agent and the adhesive molecule forming the acrylic polymer (A) (pseudo) so that the elongation distance measured at each temperature gradually decreases with increasing temperature. A crosslinked structure).

  Specifically, the method for producing the pressure-sensitive adhesive sheet of the present invention comprises (a-1) an alkyl (meth) acrylate having 8 to 18 carbon atoms of an alkyl group, (a-2) a hydroxyl group-containing monomer, (a-3) ) A cross-linked structure is formed on the acrylic polymer (A) formed by copolymerizing a nitrogen-containing monomer and, if necessary, (a-4) other acrylic acid ester using the isocyanate cross-linking agent (B). At the same time, the acrylic polymer (A) is represented by (a-2) a structure represented by —OH resulting from a hydroxyl group-containing monomer and (a-3) represented by, for example, R—N—R resulting from a nitrogen-containing monomer. In the state where the temperature is low by utilizing the coexistence of the structure (R is an alkyl group or a hydrogen atom), the charge bias between “OH” and “N” in these structures A kind of weak binding force is expressed. Such weak bond strength (bond strength due to pseudo-crosslinking) is obtained by adding an isocyanate-based crosslinking agent (B) to an acrylic polymer (A) solution obtained by copolymerizing the above-mentioned components, and isocyanate-based crosslinking. After the cross-linked structure is formed by the agent, this solution is poured to remove the solvent and cure. The pseudo-crosslinked structure, which is a weak binding force formed in this way, acts like a kind of crosslinked structure that bridges the structures. Therefore, it is presumed that such a pseudo-crosslinked structure is formed everywhere in a relatively low temperature state. As a result, the pressure-sensitive adhesive of the pressure-sensitive adhesive sheet obtained by the production method of the present invention has a relatively low temperature state. It behaves as if it was a high-density cross-linked acrylic adhesive. That is, under a relatively low temperature condition, this pressure-sensitive adhesive exhibits characteristics like a hard pressure-sensitive adhesive. Accordingly, when the pressure-sensitive adhesive sheet obtained by the production method of the present invention is cut into a desired shape, the pressure-sensitive adhesive hardly adheres to the blade of the cutter, and the threading phenomenon of the pressure-sensitive adhesive does not occur. Moreover, generation | occurrence | production of a bubble etc. can be suppressed.

  On the other hand, the pseudo-crosslinking formed as described above has a weaker interaction with an increase in temperature, and a crosslinked structure with an isocyanate-based crosslinking agent remains in the final product. Since the crosslinking density due to this isocyanate-based crosslinking agent is not so high, the pressure-sensitive adhesive becomes soft as the temperature rises, and exhibits very good form following properties when sticking under heating.

In the method for producing the pressure-sensitive adhesive sheet of the present invention having such a crosslinked structure, an acrylic polymer (A) is first produced.
This acrylic polymer (A)
(a-1) an alkyl (meth) acrylate having 8 to 18 carbon atoms in the alkyl group;
(a-2) a hydroxyl group-containing monomer,
(a-3) Nitrogen-containing monomer and, if necessary
(a-4) Copolymers with other acrylic esters.

  Examples of the alkyl (meth) acrylate having 8 to 18 carbon atoms of the alkyl group (a-1) used in the production method of the pressure-sensitive adhesive sheet of the present invention include 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, Examples include isooctyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, undeca (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, and isostearyl (meth) acrylate. These can be used alone or in combination.

  In the acrylic polymer of the present invention, the alkyl (meth) acrylate having 8 to 18 carbon atoms of the (a-1) alkyl group is 50 to 100% in 100% by weight of the monomer that forms the acrylic polymer (A). It is used in an amount of 94.9% by weight, preferably 70-94.5% by weight, more preferably 80-93% by weight. (a-1) When the amount of the alkyl (meth) acrylate having 8 to 18 carbon atoms in the alkyl group is more than 94.9% by weight, the monomer inevitably has a crosslinkable functional group (a-2) The amount of component (a-3) used is reduced, and a sufficient crosslinking density cannot be formed. On the other hand, if it is less than 50% by weight, a flexible pressure-sensitive adhesive layer coating film is not formed, and the breaking distance at a relatively low temperature (23 ° C.) is shortened.

  (A-1) An acrylic cross-linking agent that forms an acrylic polymer (A) by copolymerization with an alkyl (meth) acrylate having 8 to 18 carbon atoms in the alkyl group should use an isocyanate crosslinking agent A (meth) acrylate compound having a hydroxyl group as a crosslinkable functional group is preferred. Examples of the hydroxyl group-containing monomer (a-2) include 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 3-chloro-2-hydroxypropyl (meth) acrylate, 4-hydroxy Examples thereof include butyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, and 8-hydroxyoctyl (meth) acrylate. As the hydroxyl group-containing monomer as described above, 2-hydroxyethyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate are preferable, and these hydroxyl group-containing monomers can be used alone or in combination.

  In the acrylic polymer of the present invention, the (a-2) hydroxyl group-containing monomer is 0.1 to 10% by weight, preferably 0.5%, in 100% by weight of the monomer that forms the acrylic polymer (A). It is used in an amount of ˜5% by weight, more preferably 1 to 5% by weight. (a-2) If the amount of the hydroxyl group-containing monomer is more than 10% by weight, the crosslinking density formed by the isocyanate-based crosslinking agent becomes excessively high, and the pressure-sensitive adhesive produced by the method of the present invention becomes hard, and the level difference follows. The characteristics such as sexuality are reduced. On the other hand, when the amount is less than 0.1% by weight, the crosslinked structure formed by the isocyanate-based crosslinking agent cannot be effectively formed, the water resistance is lowered, and the strength required for the crosslinked sheet is not exhibited.

In the present invention, an acrylic polymer (A) is formed by using the (a-1) alkyl group having 8 to 18 carbon atoms (meth) acrylate and (a-2) a hydroxyl group-containing monomer (a-3) Examples of nitrogen-containing monomers include amino group-containing monomers such as dimethylaminoethyl (meth) acrylate and diethylaminoethyl (meth) acrylate,
Amide group-containing monomers such as (meth) acrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-propyl (meth) acrylamide, N-hexyl (meth) acrylamide,
Nitrogen-containing heterocycle-containing monomers such as vinylpyrrolidone, acryloylmorpholine, vinylcaprolactam,
Cyano group-containing monomers such as cyano (meth) acrylate Maleimides such as maleimide monomers such as maleimide, methylmaleimide, ethylmaleimide, propylmaleimide, butylmaleimide, hexylmaleimide, octylmaleimide, dodecylmaleimide, stearylmaleimide, phenylmaleimide and cyclohexylmaleimide Mention may be made of group-containing monomers.

  In the present invention, the (a-3) nitrogen-containing monomer is 5 to 10% by weight, preferably 5 to 9% by weight, and more preferably 6 to 10% by weight in 100% by weight of the monomer that forms the acrylic polymer (A). Copolymerize in an amount of 9% by weight. (a-3) When the amount of the nitrogen-containing monomer is more than 10% by weight, the pseudo-crosslinking density by hydrogen bonding becomes high and the pressure-sensitive adhesive of the present invention becomes hard. On the other hand, when the amount is less than 5% by weight, a pseudo-crosslinked structure due to hydrogen bonding cannot be effectively formed, and the cutting property at normal temperature, durability, and water resistance are lowered.

In this nitrogen-containing monomer (a-3), the H ₂ C═CH— group present in the molecule contributes to the copolymerization reaction, and the nitrogen atom does not participate in this polymerization reaction. Therefore, even if the nitrogen-containing monomer (a-3) is copolymerized, the nitrogen-containing group in the nitrogen-containing monomer (a-3) has the form as it is. The nitrogen atom forming this nitrogen-containing group has an unshared electron pair having the structure of N :, and in the state where molecular motion is not so active under relatively low temperature conditions, it is in the vicinity of this unshared electron pair. In addition, for example, when a non-shared electron pair such as: O: exists, the two attract each other to act as if a covalent bond is formed, and a weak binding force is generated between the two. In the present invention, this is called a pseudo-crosslinked structure. This pseudo-crosslinked structure exists stably in a low temperature state where the molecular activity is low, but the binding force becomes weak as the temperature rises and the molecular activity becomes active, and this binding force is very weak in the region above about 80 ° C. Become. This bond formation is reversible and a pseudo-crosslinked structure is formed again when the temperature is lowered.

  The acrylic polymer (A) produced in the present invention comprises the above (a-1) alkyl (meth) acrylate having 8 to 18 carbon atoms of the alkyl group, (a-2) a hydroxyl group-containing monomer, and (a-3) containing nitrogen. Although it is a copolymer of monomers, other acrylates copolymerizable with (a-4) (a-1) to (a-3) may also be copolymerized.

  Here, examples of other acrylic acid esters that may form the acrylic polymer (A) include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, iso-propyl (meth) acrylate, n-butyl (meth) acrylate, iso-butyl (meth) acrylate, tert-butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, etc. C1-C7 alkyl (meth) acrylate, 2-methoxymethyl (meth) acrylate, 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, methoxydiethylene glycol (meth) acrylate, 3-methoxypropyl (meth) acrylate, 3-ethoxypropyl (meth) acrylate , Aryls such as 4-methoxybutyl (meth) acrylate, alkoxy (meth) acrylates such as 4-ethoxybutyl (meth) acrylate, alkylene glycol (meth) acrylate, benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, etc. ) Acrylate and the like. These monomers can be used alone or in combination. Among these, it is preferable to use alkyl (meth) acrylates having 1 to 7 carbon atoms of alkyl groups such as butyl (meth) acrylate and methyl (meth) acrylate.

  In the acrylic polymer of the present invention, the above (a-4) other acrylic ester is 0 to 44.9% by weight, preferably 0 to 24%, in 100% by weight of the monomer constituting the acrylic polymer (A). It is copolymerized in an amount of 0.5% by weight, more preferably 0-13% by weight. (a-4) When the amount of the other copolymerizable monomer is more than 44.9% by weight, the main monomer (a-1) is an alkyl (meth) acrylate having 8 to 18 carbon atoms in the alkyl group. The flexibility of the pressure-sensitive adhesive layer coating film will be lost. Since the lower limit of the copolymerization amount of the (a-4) other acrylate ester is 0% by weight, it is not necessary to copolymerize the (a-4) other acrylate ester in the present invention.

In the production method of the pressure-sensitive adhesive sheet of the present invention, the components (a-1) to (a-4) shown below when producing the acrylic polymer (A)
(a-1) an alkyl (meth) acrylate having 8 to 18 carbon atoms in the alkyl group;
(a-2) a hydroxyl group-containing monomer,
(a-3) Nitrogen-containing monomer and, if necessary
(a-4) Other acrylic acid ester is copolymerized, but other monomers may be copolymerized within a range not impairing the properties of the acrylic polymer (A).

  Examples of other monomers that can be copolymerized here include vinyl acetate; (meth) acrylonitrile; cyclohexyl (meth) acrylate, benzyl (meth) acrylate, phenyl (meth) acrylate; styrene, methylstyrene, dimethylstyrene, and trimethylstyrene. Styrene, such as alkyl styrene such as propyl styrene, butyl styrene, hexyl styrene, heptyl styrene and octyl styrene, fluoro styrene, chloro styrene, bromo styrene, dibromo styrene, iodo styrene, nitro styrene, acetyl styrene and methoxy styrene A monomer etc. can be used in the range which does not impair the effect of this application, Preferably it is 0 to 5 weight%.

  The acrylic polymer (A) obtained by the method for producing a pressure-sensitive adhesive sheet of the present invention has substantially no acidic group. Here, having no acidic group means that a monomer having an acidic group is not added intentionally at the time of copolymerization, and it is usually 0.5 mgKOH / g or less in terms of the acid value of the resulting polymer. . Examples of the monomer having an acidic group include a monomer having a carboxyl group such as (meth) acrylic acid, maleic acid, and itaconic acid, a monomer having a phosphoric acid group, and a monomer having a sulfuric acid group. When the acrylic polymer (A) is produced in the method for producing the pressure-sensitive adhesive sheet of the present invention, the above acidic group-containing monomer is not copolymerized. Since the acid group-containing monomer is not copolymerized in this way, the acrylic polymer (A) does not corrode even if it comes into direct contact with the metal or metal oxide wiring, and the pressure-sensitive adhesive sheet of the present invention Even if the wiring comes into contact with the pressure-sensitive adhesive forming the wire, it is possible to impart the characteristic that the resistance value of the wiring is not changed over a long period of time.

  Furthermore, the weight average molecular weight of the acrylic monomer (A) obtained by the method for producing the pressure-sensitive adhesive sheet of the present invention is 50,000 or more and less than 400,000, preferably 200,000 to 380,000. By using the acrylic polymer (A) having such a weight average molecular weight, the viscosity does not increase remarkably even if the solid content of the coating solution is increased. Therefore, a sheet having a desired thickness can be obtained without repeated fluting. Can be manufactured.

The acrylic polymer (A) is produced by solution polymerization.
As the polymerization solvent used here, for example, ethyl acetate, methyl ethyl ketone, toluene, acetone, isopropyl alcohol and the like can be used. Specifically, a polymerization solvent and a monomer are charged into a reaction vessel, a polymerization initiator is added in an inert gas atmosphere such as nitrogen gas, and the reaction start temperature is usually 40 to 100 ° C., preferably 50 to 80 ° C. The reaction system is maintained at a temperature of usually 50 to 90 ° C., preferably 70 to 90 ° C. for 4 to 20 hours.

  Examples of the reaction initiator used for solution polymerization include azo initiators and peroxide initiators. These initiators are usually used in an amount in the range of 0.01 to 5 parts by weight with respect to 100 parts by weight of the monomer. Further, a polymerization initiator, a chain transfer agent, a monomer, and a solvent may be appropriately added during the polymerization reaction.

  Under the above conditions, the weight average molecular weight can be adjusted by adjusting reaction conditions such as the type of solvent used, the type and amount of polymerization initiator, the reaction time, the reaction start temperature, and the reaction temperature.

  The glass transition temperature (Tg) of the acrylic polymer (A) obtained by the above method can be calculated, for example, according to the Fox equation. When the acrylic polymer (A) as described above is produced, the glass transition temperature (Tg) of the acrylic polymer obtained from the Fox formula for the pressure-sensitive adhesive obtained by selecting the monomer to be used is usually -70 ° C. ˜0 ° C., preferably −70 ° C. to −50 ° C. By using the acrylic polymer (A) having such a glass transition temperature (Tg), a pressure-sensitive adhesive having excellent adhesive strength at room temperature can be obtained.

  After producing the acrylic polymer (A) as described above, in the method for producing the pressure-sensitive adhesive sheet of the present invention, the acrylic polymer (A) is crosslinked with the isocyanate crosslinking agent by blending an isocyanate crosslinking agent.

  Examples of the isocyanate-based crosslinking agent (B) used in the present invention include molecules such as tolylene diisocyanate, xylylene diisocyanate, chlorophenylene diisocyanate, hexamethylene diisocyanate, tetramethylene diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate. A compound having two or more isocyanate groups: a compound obtained by addition reaction with a polyhydric alcohol such as trimethylolpropane or pentaerythritol, an isocyanurate compound, a burette type compound, a known polyether polyol or polyester polyol, Two or more polymers are added in the urethane prepolymer type molecule that has undergone addition reaction with acrylic polyol, polybutadiene polyol, polyisoprene, etc. Mention may be made of compounds having a socyanate group.

  Among these, xylylene diisocyanate and its trimethylolpropane adduct are preferable in that it can improve conformability to the adherend and reduce entrainment of bubbles during bonding, and can suppress outgassing at high temperatures, In addition, hexamethylene diisocyanate, its trimethylolpropane adduct, and isocyanurate derivatives are preferable in that the step following property of the attached surface can be improved and the heat-resistant foaming property can be improved.

Such isocyanate-based crosslinking agents (B) can be used alone or in combination.
By blending the isocyanate-based crosslinking agent (B) in this way, the cohesive force of the pressure-sensitive adhesive is improved, and even if air bubbles are slightly involved at the time of pasting, expansion of the air bubbles can be suppressed.

  In the manufacturing method of the adhesive sheet of this invention, 0.1-30 weight part of isocyanate type crosslinking agents (B) are preferable with respect to 100 weight part of said acrylic polymer (A) and this acrylic polymer (A), Is blended in an amount of 0.1 to 10 parts by weight.

  In the present invention, a mixed liquid of an acrylic polymer (A) and an isocyanate crosslinking agent (B) can be used as a coating liquid. In the production method of the present invention, the acrylic polymer (A) is supplied as a solution in an organic solvent, and the isocyanate crosslinking agent as described above is dissolved in the organic solvent. Therefore, only the isocyanate crosslinking agent (B) is added with stirring. The acrylic polymer (A) and the isocyanate crosslinking agent (B) can be easily mixed.

  In the present invention, the coating solution obtained as described above is poured on the surface of the support (1) subjected to the peeling process. For fluency, a known method can be used, and examples thereof include spin coating, a doctor blade, and a calender roll.

  The coating solution containing the acrylic polymer (A) and isocyanate crosslinking agent (B) used in the present invention in the solvent has a low weight average molecular weight (Mw) of the acrylic polymer (A), so that ethyl acetate, methyl ethyl ketone The concentration of non-volatile components can be adjusted to a desired concentration using a solvent such as acetone, toluene, and isopropyl alcohol. Therefore, by using the pressure-sensitive adhesive constituting the pressure-sensitive adhesive sheet of the present invention, the thickness of the pressure-sensitive adhesive after coating can be easily set to a desired thickness. In particular, the pressure-sensitive adhesive of the present invention can easily prepare a solution having a high nonvolatile content, and for example, the nonvolatile content can be adjusted within a range of 10 to 70%, preferably 20 to 60%. A pressure-sensitive adhesive layer having a desired thickness can be formed with a small number of coatings. Further, by using a solution having a high nonvolatile content as described above, the leveling property of the coating film after coating and drying is improved, and the drying time is shortened and the workability is improved. Furthermore, since the amount of volatile solvent is small, the burden on the environment is also reduced.

  Utilizing such characteristics, the pressure-sensitive adhesive sheet of the present invention is coated with the above pressure-sensitive adhesive to a thickness in the range of 25 to 1000 μm, preferably in the range of 25 to 500 μm, and after removing the solvent. It is obtained by curing.

  In the production method of the present invention, the pressure-sensitive adhesive sheet can use a mixed liquid of the acrylic polymer (A) and the isocyanate crosslinking agent (B) as a coating liquid. The non-volatile content of this coating solution is usually adjusted to 10 to 70%, preferably 20 to 60%. The coating solution prepared in this manner is dried on the surface of a support (eg, release-treated PET) whose surface has been subjected to a release treatment. The dry thickness is in the range of 10 to 1000 μm, preferably in the range of 25 to 500 μm. It is obtained by applying a cover film having a surface peeled off to the surface of the formed pressure-sensitive adhesive layer and then curing it. The pressure-sensitive adhesive sheet of the present invention is applied by applying the coating liquid on the support (1) peel-processed as described above, removing the solvent, and then curing by placing another support (2) on the application surface. Therefore, the support is not contained near the inside of the pressure-sensitive adhesive sheet, and is a double-sided adhesive pressure-sensitive adhesive sheet without a support. However, the pressure-sensitive adhesive sheet of the present invention may be a three-layered pressure-sensitive adhesive sheet in which pressure-sensitive adhesive layers are formed on both surfaces of a support.

  After applying the coating solution to the support (1) thus peeled off, the solvent is usually removed by heating. The temperature at this time can be variously selected depending on the type of solvent used, but is usually 50 to 150 ° C, preferably 60 to 100 ° C.

After removing the solvent as described above, the surface of the surface where the pressure-sensitive adhesive layer is released is covered with a support (2) and cured.
In the present invention, the curing is usually performed at a temperature of 0 to 50 ° C. for 1 day to 10 days as described above. During this curing, the crosslinking reaction by the isocyanate-based crosslinking agent, N and OH, N and NH, and Between these, a pseudo-crosslinked structure is formed. The cross-linking reaction with the isocyanate-based cross-linking agent formed here does not break the bond even when the temperature rises and forms a stable cross-linked structure, but pseudo-cross-linking is comparative at a relatively low temperature (for example, 23 ° C.). Is forming a stable bond, but as the temperature rises, the activity of the molecules forming the pressure-sensitive adhesive increases, and the weak binding force forming the pseudo-crosslink cannot resist the active activity of the molecules. The pseudo-crosslinking density decreases with increasing temperature. For this reason, the breaking distance of the pressure-sensitive adhesive obtained by the method of the present invention is shortened by the amount by which the bonding force due to pseudo-crosslinking is weakened.

That is, the pressure-sensitive adhesive tape obtained by the production method of the present invention has a characteristic that the breaking distance measured by a predetermined method becomes shorter as the temperature rises. In order to express such characteristics clearly, FIG. 7 shows fracture distances at 20 ° C., 60 ° C., and 80 ° C. As shown in FIG. 7, the breaking distance at 23 ° C. of the pressure-sensitive adhesive sheet is usually in the range of 150 to 50 mm, preferably in the range of 110 to 50 mm, and the breaking distance at 60 ° C. is usually 143 to 40 mm. Within the range, preferably within the range of 100 to 40 mm, the breaking distance at 80 ° C. is usually within the range of 136 to 30 mm, preferably within the range of 90 to 30 mm. In addition, said value is the breaking distance of the tension test in each temperature on the conditions of the speed of 100 mm / min about the adhesive sheet test piece of thickness 200 micrometers and width 10mm formed from the adhesive sheet manufactured by the manufacturing method of this invention. It is a value when is measured. And it is preferable to form a pseudo-crosslinked structure so that the breaking distances at 23 ° C., 60 ° C. and 80 ° C. measured under the above conditions have a relationship represented by the following formula (1).
23 ° C. breaking distance> 60 ° C. breaking distance> 80 ° C. breaking distance (1)
Such a tendency is a tendency not to be observed when only an isocyanate-based crosslinking agent is used as a crosslinking agent. In the pressure-sensitive adhesive obtained by the production method of the present invention, in addition to the crosslinked structure by an isocyanate-based crosslinking agent, the above-described tendency is observed. This confirms that a pseudo-crosslinked structure is formed between (a-2) the oxygen atom in the hydroxyl group-containing monomer and (a-3) the nitrogen atom in the nitrogen-containing monomer.

  In the production method of the pressure-sensitive adhesive sheet of the present invention, the pressure-sensitive adhesive forming the pressure-sensitive adhesive sheet comprises (a-1) an alkyl (meth) acrylate having 8 to 18 carbon atoms in an alkyl group, and (a-2) A specific amount of an isocyanate polymer obtained by copolymerizing a hydroxyl group-containing monomer, (a-3) a nitrogen-containing monomer, and (a-4) other acrylic ester at a predetermined ratio A pressure-sensitive adhesive sheet in which the breaking distance measured at a speed of 100 mm / min for a pressure-sensitive adhesive sheet test piece having a thickness of 200 μm and a width of 10 mm obtained by forming a pseudo-crosslink is shortened with increasing temperature while being crosslinked using a crosslinking agent. In the present invention, in addition to the acrylic polymer (A), in the present invention, a low molecular weight (having a hydrogen-bonding functional group and having substantially no acidic group and having a weight average molecular weight of less than 100,000 ( (Meth) acrylic polymer It may be blended.

The low molecular weight (meth) acrylic polymer that can be used in the present invention is usually a copolymer of a hydrogen-bonding functional group-containing monomer and another monomer.
As the hydrogen-bonding functional group-containing monomer that forms this low molecular weight (meth) acrylic polymer, the above-mentioned hydroxyl group-containing monomer (a-2) and nitrogen-containing monomer (a-3) can usually be used, and If necessary, it can be obtained by copolymerizing other monomers.

  Examples of other monomers used here include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, iso-propyl (meth) acrylate, n-butyl (meth) acrylate , Iso-butyl (meth) acrylate, tert-butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, nonyl Aliphatic (meth) acrylates such as (meth) acrylate, decyl (meth) acrylate, undeca (meth) acrylate, dideca (meth) acrylate and the like; alicyclic rings such as cyclohexyl (meth) acrylate and isobornyl (meth) acrylate Genus (meth) acrylate; benzyl (meth) acrylate, Aromatic (meth) acrylates such as nyl (meth) acrylate; furthermore, styrene, methyl styrene, dimethyl styrene, trimethyl styrene, propyl styrene, butyl styrene, hexyl styrene, heptyl styrene, octyl styrene and other alkyl styrene, fluoro styrene Styrene monomers such as chlorostyrene, bromostyrene, dibromostyrene, iodinated styrene, nitrostyrene, acetylstyrene and methoxystyrene; glycidyl (meth) acrylate, vinyl acetate, acrylonitrile and the like. In the present invention, methyl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate and the like can be preferably used. These monomers can be used alone or in combination.

  In the low molecular weight (meth) acrylic polymer that can be used in the present invention, the hydrogen-bonding functional group-containing monomer and the other monomer are usually in a weight ratio of 0.1-20: 99.9-80, preferably Is copolymerized in a weight ratio of 0.5 to 15: 99.5 to 85.

  The low molecular weight (meth) acrylic polymer used in the present invention has a weight average molecular weight (Mw) of less than 100,000, preferably 5,000 or more and less than 50,000. When a low molecular weight (meth) acrylic polymer having such a weight average molecular weight (Mw) is used together with the above-mentioned acrylic polymer (A), good cohesive force and step following ability are exhibited.

  The low molecular weight (meth) acrylic polymer that can be used in the present invention also has substantially no acidic group. Here, having no acidic group has the same meaning as in the acrylic monomer (A). Thus, since the low molecular weight (meth) acrylic polymer used in the present invention is not copolymerized with an acidic group-containing monomer, the low molecular weight (meth) acrylic polymer used in the present invention is a metal or metal oxide. Even if it is in direct contact with a wiring made of a material, these are not corroded, and the pressure-sensitive adhesive of the present invention can be given a characteristic that the resistance value of the wiring is not changed over a long period of time.

  In the present invention, when producing the low molecular weight (meth) acrylic polymer as described above, the glass transition temperature (Tg) of the low molecular weight (meth) acrylic polymer obtained by the Fox formula obtained is usually −70. The monomer is selected so that it is within the range of from ℃ to 110 ℃, preferably from -65 ℃ to 100 ℃. By using a low molecular weight (meth) acrylic polymer having such a glass transition temperature (Tg), a pressure-sensitive adhesive having excellent adhesive strength at room temperature can be obtained.

  In addition, when the pressure-sensitive adhesive of the present invention uses the acrylic polymer (A) and the low molecular weight (meth) acrylic polymer in combination, the weight average molecular weight of the acrylic polymer (A) is low molecular weight. The relationship between the weight average molecular weight of the (meth) acrylic polymer is always larger than the weight average molecular weight of the (meth) acrylic polymer, and the difference between the weight average molecular weight of the acrylic polymer (A) and the weight average molecular weight of the low molecular weight (meth) acrylic polymer is It is preferable to select the acrylic polymer (A) and the low molecular weight (meth) acrylic polymer so that they are within the range of 80,000 to 390,000.

  The pressure-sensitive adhesive constituting the pressure-sensitive adhesive sheet of the present invention includes an antioxidant, a light stabilizer, a metal corrosion inhibitor, a tackifier, a plasticizer, and an antistatic agent as long as the effects of the pressure-sensitive adhesive of the present invention are not impaired. Further, a crosslinking accelerator, a reworking agent and the like can be blended.

The gel fraction of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet thus obtained is usually 10 to 80%, preferably 40 to 70%.
Thus, the pressure-sensitive adhesive sheet obtained by the production method of the present invention has the above-described configuration, and the above-mentioned acrylic polymer (A ) And the isocyanate compound (B) ensure good characteristics.

The pressure-sensitive adhesive sheet thus obtained can be attached to various members, and is particularly suitable for attaching a laminate for a touch panel in which different types of members are attached.
The manufacturing method of the laminated body for touchscreens of this invention sticks a touchscreen formation member using the adhesive sheet formed as mentioned above.

As shown in FIGS. 1 and 2, the touch panel unit includes a resistive touch panel unit (see FIG. 1) and a capacitive touch panel unit (see FIG. 2).
FIG. 1 shows an example of a resistive film type touch panel unit 10-1.

  As shown in FIG. 1, the resistive touch panel unit 10-1 is formed by bonding the upper laminate 11-1 and the lower laminate 13-1 so that the gap 34 is formed by the bonding agent 30. In the gap 34, the spacer 32 is disposed in order to effectively secure the gap width.

  In the upper laminate 11-1, a transparent conductive film 27-1 made of metal or metal oxide is disposed facing the gap 34. This transparent conductive film 27-1 is formed of a conductive material having transparency such as ITO (indium tin oxide), ATO (antimony tin oxide) tin oxide, and is usually made of polyethylene terephthalate (PET) as shown in FIG. ), Polycarbonate (PC), polymethyl methacrylate (PMMA), or a transparent member such as glass.

  A surface support 21-1 is disposed on the outermost surface of the upper laminate 11-1. This surface support 21-1 is usually a transparent member such as highly transparent glass, or a transparent plastic such as polyethylene terephthalate (PET), polycarbonate (PC), polymethyl methacrylate (PMMA), cycloolefin polymer (COP). Film or plastic board.

In order to adhere the surface support 21-1 and the upper electrode support 25-1, an adhesive layer 23-1 made of the adhesive of the present invention is formed.
Similarly, a transparent conductive film 27-2 made of a metal or metal oxide is formed on the lower laminated body 13-1 so as to face the gap 34. The transparent conductive film 27-2 is made of ITO, ATO, oxidation, or the like. It is made of a conductive material having transparency such as tin. Usually, the transparent electrode film 27-2 is made of a transparent film such as polyethylene terephthalate (PET), polycarbonate (PC), polymethyl methacrylate (PMMA) or a transparent member such as glass as shown in FIG. Form on the surface of -2.

  A deep surface support 21-2 is formed at the deepest portion of the lower laminate 13-1 so as to face the surface of a flat panel display (FPD). The deep surface support 21-2 is made of glass or the like. It is formed using a transparent member, a transparent plastic film such as polyethylene terephthalate (PET), polycarbonate (PC), polymethyl methacrylate (PMMA), or cyclopolyolefin polymer (COP), or a highly transparent member such as a plastic plate.

In the lower laminate 13-1, in order to bond the deep surface support 21-2 and the lower electrode support 25-2, an adhesive layer 23-2 made of an adhesive sheet obtained by the production method of the present invention. Form.
Moreover, the adhesive sheet obtained by the manufacturing method of this invention may be used as the bonding agent 30. FIG.

  Note that a circuit is formed in the transparent conductive films 27-1 and 27-2, and by applying pressure with a finger or the like from above the surface support 21-1, a gap 34 in a portion where pressure is applied is formed. It disappears and the transparent conductive films 27-1 and 27-2 come into contact with each other and are energized to detect the pressed portion.

  In the resistive film type touch panel unit 10-1, the thickness of the surface support 21-1 is usually 25 to 2000 μm, and the thickness of the upper transparent electrode film 27-1 is usually 25 to 100 nm. The thickness of the body 25-1 is usually 25 to 2000 μm. As described above, the thickness of the pressure-sensitive adhesive layer 23-1 for laminating them is in the range of 10 to 1000 μm, preferably in the range of 25 to 500 μm.

  Similarly, in the resistance film type touch panel unit, the thickness of the deep support 21-2 is usually 25 to 2000 μm, and the thickness of the lower transparent electrode film 27-2 is usually 25 to 100 nm. The thickness of the body 25-2 is usually 25 to 2000 μm. As described above, the thickness of the pressure-sensitive adhesive layer 23-2 on which these layers are laminated is in the range of 25 to 1000 μm, preferably in the range of 25 to 500 μm.

Further, in the resistive film type touch panel unit 10-1, the width of the gap formed at the center is usually in the range of 1 to 2000 μm.
On the other hand, the capacitive touch panel unit 10-2 generally has a central support made of a highly transparent member such as glass, polycarbonate (PC), polyethylene terephthalate (PET), cycloolefin polymer (COP), polymethyl methacrylate, and the like. The upper laminate 15-1 and the lower laminate 15-2 are often arranged with the body 60 in between.

  In the upper laminate 15-1 of the capacitive touch panel 10-2, a transparent conductive film 57-1 is disposed so as to be in contact with the central support 60, and a cover glass or polyethylene terephthalate (PET) is provided on the outermost surface. A surface support 51-1 made of a light transmitting member such as polycarbonate (PC), polymethyl methacrylate (PMMA), or cyclopolyolefin polymer (COP) is disposed. A pressure-sensitive adhesive layer 53-1 made of a pressure-sensitive adhesive sheet obtained by the production method of the present invention is disposed so that the transparent conductive film 57-1 and the surface support 51-1 are bonded. The pressure-sensitive adhesive layer 53-1 is in direct contact with the transparent conductive film 57-1.

  On the other hand, in the upper laminate 15-2 in the capacitive touch panel unit 10-2, a transparent conductive film 57-2 is disposed so as to be in contact with the central support 60, and a cover glass or polyethylene terephthalate is provided at the deepest portion. A surface support 51-2 made of a light transmissive member such as (PET), polycarbonate (PC), polymethyl methacrylate (PMMA), cyclopolyolefin polymer (COP) is disposed. The pressure-sensitive adhesive layer 53-2 made of the pressure-sensitive adhesive sheet obtained by the production method of the present invention is disposed so as to bond the transparent conductive film 57-2 and the deepest surface support 51-2. The pressure-sensitive adhesive layer 53-2 is in direct contact with the transparent conductive film 57-2.

In the capacitive touch panel unit 10-2, the deepest surface support 51-2 is disposed so as to face the flat panel display.
In the capacitive touch panel unit 10-2, the thickness of the upper laminate 51-1 is usually 175 to 3000 μm, and the thickness of the upper transparent electrode film 57-1 is usually 25 to 100 nm. The thickness of the pressure-sensitive adhesive layer 53-1 to be bonded is 10 to 1000 μm as described above. In the lower laminate 15-2, the thickness of the lower transparent electrode film 57-2 is usually 25 to 100 nm, and the thickness of the deepest surface support 51-2 is usually 25 to 2000 μm. As described above, the thickness of the pressure-sensitive adhesive layer for adhering is 25 to 1000 μm. Further, the thickness of the central support 60 between the upper laminate 15-1 and the lower laminate 15-2 is usually in the range of 25 to 2000 μm.

  The upper electrode film 51-1 and the lower electrode film 51-2 form a circuit. Further, in the capacitive touch panel unit 10-2 shown in FIG. 2, the upper electrode film 10-2 is formed as two series of circuits provided independently in the X-axis direction and the Y-axis direction, respectively. The laminated body 15-2 can also be omitted.

In the capacitive touch panel, the contact position is detected by reading the change in the capacitance of the contact portion caused by the finger touching the surface of the touch panel unit 10-2.
For the touch panel unit as described above, for example, frame printing is performed on the surface of the edge surface support 51-1 that is in contact with the adhesive shown by A in FIG. This frame printing portion is shown in an enlarged manner in FIG. In FIG. 3, the frame printing portion is indicated by the number 62. The thickness (t ₀ ) of the frame printing portion 62 is normally 10 to 50 μm, and its cross section is formed in a substantially rectangular shape. Since the pressure-sensitive adhesive layer 53-1 is formed by sticking the pressure-sensitive adhesive sheet obtained by the above-described production method of the present invention to the surface support 51-1, the pressure-sensitive adhesive layer formed on the pressure-sensitive adhesive sheet is hard. If the shape followability is poor, as shown in FIG. 4 (a), the adhesive layer 53-1 is located at the end of the frame printing portion 62 and between the surface support 51-1 and the surface support 51-1. In addition, a gap 64 that does not contact any of the edge portions of the frame printing portion 62 is formed. Originally, as shown in FIG. 4 (b), the adhesive layer 53-1 must be in close contact with the edge portions of the surface support 51-1 and the frame printing portion 62 without forming the gap 64.

  However, in the pressure-sensitive adhesive based on a pressure-sensitive adhesive having a weight average molecular weight of 400,000 to 1.6 million as in the past, the shape of the pressure-sensitive adhesive layer cannot be changed due to such a very fine shape change, and the gap 64 is formed. It will be formed. In particular, a pressure-sensitive adhesive sheet having a high weight average molecular weight and a high density of isocyanate crosslinking cannot follow the fine changes in the shape as described above, and easily forms voids.

  The pressure-sensitive adhesive layer 53-1 constituting the laminate for a touch panel obtained by the production method of the present invention in which the surface support, the pressure-sensitive adhesive layer, and the transparent electrode film (which may have a support) are laminated is as described above. The acrylic polymer (A) having a specific composition and having a weight average molecular weight (Mw) of 50,000 or more and less than 400,000 is cross-linked with an isocyanate cross-linking agent (C) and forms a simulated strength. Thus, the shape followability is extremely excellent at a high temperature, and the gap 64 is not formed around the frame printing portion 62.

  When the laminate for a touch panel formed by the manufacturing method of the present invention uses a member that easily generates outgas such as polycarbonate (PC) as the support 51-2 as shown in FIG. When the test is performed under the condition of 80 ° C., outgas from the support may be generated to generate bubbles 66 between the support and the pressure-sensitive adhesive layer. Even if a support that does not generate outgas is used, bubbles 68 may be involved when the support and the pressure-sensitive adhesive layer are bonded to each other, and if this bubble grows due to a temperature change, it will cause foaming. The pressure-sensitive adhesive forming the pressure-sensitive adhesive sheet obtained by the production method of the present invention has a specific composition, and an acrylic polymer (A) having a weight average molecular weight (Mw) of 50,000 or more and less than 400,000 is an isocyanate crosslinking agent ( B) is cross-linked as well as forming a pseudo-crosslink, so it has a very high cohesive force at low temperatures, and foaming due to outgassing and entrained bubble growth as described above is caused by high cohesive force. It can be suppressed. Therefore, the foaming as described above is hardly observed in the laminate for a touch panel formed by the production method of the present invention.

  Moreover, in the laminated body for touch panels, when a member is left under durability test conditions (60 ° C., 90%), moisture may enter from the support side and the end as shown in FIG. Under high temperature conditions, the infiltrated moisture does not precipitate, but when the temperature decreases, the infiltrated moisture precipitates, forming visible droplets, and the touch panel laminate is whitened. The haze value increases. The pressure-sensitive adhesive layer that forms the laminate for a touch panel manufactured by the method of the present invention has a specific composition, so that moisture is dispersed in the pressure-sensitive adhesive layer even if moisture enters from the support layer or the end portion, Since no visible droplets are formed, the haze value is hardly increased due to the whitening phenomenon.

  Furthermore, since the pressure-sensitive adhesive forming the pressure-sensitive adhesive sheet obtained by the production method of the present invention does not substantially contain acidic groups, the pressure-sensitive adhesive directly contacts a transparent conductive film made of metal or metal oxide. Even so, the change in the resistance value of the transparent electrode film is about 10% at the maximum, and this change is an amount that does not cause any problem in driving the touch panel.

  As described above, the laminate for a touch panel formed by the production method of the present invention has an alkyl polymer (A) having a specific composition as a pressure-sensitive adhesive constituting the pressure-sensitive adhesive sheet and having a weight average molecular weight of 50,000 or more and less than 400,000, The support sheet and the transparent conductive film are adhered to each other using an adhesive sheet having an isocyanate-based crosslinking agent (B), and has an excellent form following ability. No voids are formed, foaming due to entrainment can be suppressed, and moisture is not precipitated, so that the pressure-sensitive adhesive layer is not whitened and the haze value is not increased.

EXAMPLES Next, the present invention will be described in more detail with reference to examples of the present invention, but the present invention is not limited thereto.
By the method shown below, the weight average molecular weight, gel fraction, nonvolatile content, wet heat whitening property, heat-resistant foaming property, ITO corrosiveness, coating property, workability, step following property, adhesive strength, breaking distance (SS The curve was measured.
〔Measuring method〕
<Molecular weight>
The weight average molecular weight (Mw) in terms of standard polystyrene was determined using gel permeation chromatography (GPC).
Measuring condition apparatus: HLC-8120GPC (manufactured by Tosoh Corporation)
Column: TSK-GEL HXL-H (guard column, manufactured by Tosoh Corporation)
TSK-GEL 7000HXL (manufactured by Tosoh Corporation)
TSK-GEL GMHXL (manufactured by Tosoh Corporation)
TSK-GEL GMHXL (manufactured by Tosoh Corporation)
TSK-GEL G2500HXL (manufactured by Tosoh Corporation)
Sample concentration: diluted with tetrahydrofuran to 1.0 mg / cm ³ Mobile phase solvent: tetrahydrofuran Flow rate: 1.0 cm ³ / min
Column temperature: 40 ° C
<Gel fraction>
About 0.1 g of adhesive after aging at 23 ° C. for 7 days was collected in a sampling bottle, 30 cc of ethyl acetate was added and shaken for 4 hours, and then the contents of this sample bottle were filtered through a 200 mesh stainless steel wire mesh. The residue on the wire mesh was dried at 100 ° C. for 2 hours, and the dry weight was measured.
Gel fraction (%) = (Dry weight / Adhesive sampling weight) × 100
<Haze>
The release sheet on one side of the obtained pressure-sensitive adhesive sheet was peeled off, and a 38 μm-thick polyethylene terephthalate film was bonded together and cut into a size of 50 mm × 50 mm. Next, the other release film was peeled off, bonded to a 2 mm thick PC plate, treated in an autoclave at 50 ° C. and 5 atm for 20 minutes, and then allowed to stand for 1 hour to prepare a test piece.

  After measuring the haze before the endurance test of the prepared test piece, it was left to stand in an environment of 85 ° C. and 85%. After 500 hours, the test piece was taken out and allowed to stand at room temperature for 1 hour, and then the haze was measured to determine the difference from the haze before the durability test.

For the measurement of haze, MH-150 (manufactured by Murakami Color Research Laboratory Co., Ltd.) was used.
<Foaming>
The release sheet on one side of the obtained pressure-sensitive adhesive sheet was peeled off, and a 38 μm thick polyethylene terephthalate film on which ITO was vapor-deposited was bonded and cut into a size of 50 mm × 50 mm. Next, the other release film was peeled off, bonded to a glass substrate having a thickness of 2 mm, treated in an autoclave at 50 ° C. and 5 atm for 2 minutes, and then allowed to stand for 1 hour to prepare a test piece.

After measuring the haze for the durability test of the prepared test piece, it was allowed to stand at 60 ° C., 90% environment, 85 ° C., dry environment, 85 ° C., 85% environment. The test piece after the elapse of 500 hours was taken out and allowed to stand at room temperature for 1 hour, and then the degree of foaming was visually confirmed.
The criteria for evaluation are as follows.
(Evaluation) (Content)
○: No bubbles can be visually confirmed in the adhesive layer.
X: Large bubbles can be confirmed. Alternatively, the pressure-sensitive adhesive layer is floating from the substrate or the adherend.

<ITO resistance change rate>
In the foaming test, the resistance value before the foaming test was measured in advance, and then the resistance value of the test piece placed in an environment of 85 ° C. and 85% was measured to obtain the rate of change of the resistance value.

The resistance value was measured using a tester (manufactured by Sanwa Denki Keiki Co., Ltd., Digital Multimeter PC510).
<Adhesive strength to ITO>
A peeled polyethylene terephthalate film (PET film) on one side of the obtained pressure-sensitive adhesive sheet was peeled off, a 25 μm PET film was bonded, and cut into a width of 25 mm to prepare a test piece.

Next, the other peelable PET film of the test piece was peeled off and bonded to a PET film on which ITO was deposited.
The test piece was peeled off and the adhesive strength against ITO was determined from the peel strength.
<Step following capability>
The peeled PET film on one side of the obtained pressure-sensitive adhesive sheet was peeled off, a 25 μm PET film was bonded, and cut into 50 mm × 50 mm to prepare a test piece.

Next, the PET film cut to 25 mm × 25 mm is placed on the glass plate, the peeled PET film on the other side of the prepared test piece is peeled off, and the PET film on the glass plate is pasted so as to cover the entire surface. The sample was allowed to stand in an 80 ° C. environment for 500 hours and then allowed to stand at room temperature for 1 hour, and the appearance of the step portion was visually observed.
(Evaluation) (Content)
○: Bubbles cannot be visually confirmed in the stepped portion.
X: Bubbles can be clearly confirmed visually at the stepped portion.

<Measurement of SS curve breaking distance>
The SS curve breaking distance measurement test uses a strip-shaped test piece with a thickness of 200 μm, a width of 10 mm, and a length of 2 cm. The chuck is set to 1 cm, and the upper end and lower end of the above test piece are fixed. The test piece was pulled at a rate of 100 mm / min at temperatures of 23 ° C., 60 ° C., and 80 ° C., and the distance to break was measured.
[Example 1]
In a reactor equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen introduction tube, 90 parts by weight of 2-ethylhexyl acrylate (2EHA), 2 parts by weight of 2-hydroxyethyl acrylate (2-HEA), 8 parts by weight of acrylamide (AM) Parts, 100 parts by weight of ethyl acetate (EtAc) and 20 parts by weight of methyl ethyl ketone (MEK) were added, and the temperature was raised to 63 ° C. while introducing nitrogen gas.

Next, 0.1 part by weight of azobisisobutyronitrile (AIBN) was added, and a polymerization reaction was performed at 63 ° C. for 5 hours in a nitrogen atmosphere.
After completion of the reaction, the reaction mixture was diluted with ethyl acetate (EtAc) and adjusted to a solid content concentration of 30% to obtain acrylic polymer 1 (polymer 1) having a weight average molecular weight of 350,000. The glass transition temperature (Tg) calculated | required by the formula of Fox about the obtained polymer 1 is -60 degreeC.

  To the polymer 1 obtained as described above, Takenate D-110N (manufactured by Mitsui Chemicals, Inc.) as an isocyanate curing agent was added at a ratio of 0.4 part by weight with respect to 100 parts by weight of the solid content of polymer 1. Thus, a pressure-sensitive adhesive composition was produced (solid content: 30% by weight).

  The obtained pressure-sensitive adhesive composition was applied onto a release-treated polyethylene terephthalate (PET) film to a dry thickness of 50 μm, dried at 80 ° C. for 2 minutes to remove the solvent, A PET film that had been subjected to a release treatment was bonded to the pressure-sensitive adhesive surface and aged at 23 ° C. for 7 days to produce a pressure-sensitive adhesive sheet.

  The obtained adhesive sheet was measured for the breaking distance at 23 ° C., 60 ° C. and 80 ° C. according to the method described above. The pressure-sensitive adhesive sheet thus produced has a breaking distance at 23 ° C. of 100 mm, a breaking distance at 60 ° C. is 90 mm, a breaking distance at 80 ° C. is 70 mm, and a breaking distance at 60 ° C. is 90% of the breaking distance at 23 ° C. %, And the breaking distance at 80 ° C. corresponds to 78% of the breaking distance at 60 ° C.

FIG. 7 shows the SS curve of the breaking distance obtained as described above, and Table 1 shows the breaking distance.
In addition, the obtained pressure-sensitive adhesive sheet was evaluated for gel fraction, haze change, glass foaming property, step following property, ITO resistance change rate, workability and thick coating suitability, and are shown in Table 1.
[Example 2]
In a reactor equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen introduction tube, 88 parts by weight of 2-ethylhexyl acrylate (2EHA), 2 parts by weight of 2-hydroxyethyl acrylate (2-HEA), 10 parts by weight of acrylamide (AM) Parts, 100 parts by weight of ethyl acetate (EtAc) and 20 parts by weight of methyl ethyl ketone (MEK) were added, and the temperature was raised to 63 ° C. while introducing nitrogen gas.

Next, 0.1 part by weight of azobisisobutyronitrile (AIBN) was added, and a polymerization reaction was performed at 70 ° C. for 5 hours in a nitrogen atmosphere.
After completion of the reaction, the reaction mixture was diluted with ethyl acetate (EtAc) and adjusted to a solid content concentration of 30% to obtain acrylic polymer 2 (polymer 2) having a weight average molecular weight of 350,000. The glass transition temperature (Tg) calculated | required by the formula of Fox about the obtained polymer 2 is -58 degreeC.

  To the polymer 2 obtained as described above, Takenate D-110N (manufactured by Mitsui Chemicals, Inc.) as an isocyanate curing agent was added at a ratio of 0.4 part by weight based on 100 parts by weight of the solid content of the polymer 2. Thus, a pressure-sensitive adhesive composition was obtained (solid content: 30% by weight).

  The obtained pressure-sensitive adhesive composition was applied onto a release-treated polyethylene terephthalate (PET) film to a dry thickness of 50 μm, dried at 80 ° C. for 2 minutes to remove the solvent, The release-treated PET film was bonded to the pressure-sensitive adhesive surface and aged at 23 ° C. for 7 days to obtain a pressure-sensitive adhesive sheet.

  The obtained adhesive sheet was measured for the breaking distance at 23 ° C., 60 ° C. and 80 ° C. according to the method described above. The pressure-sensitive adhesive sheet thus produced has a breaking distance at 23 ° C. of 80 mm, a breaking distance at 60 ° C. of 60 mm, a breaking distance at 80 ° C. of 40 mm, and a breaking distance of 60 ° C. is 75% of the breaking distance of 23 ° C. The breaking distance at 80 ° C. corresponds to 67% of the breaking distance at 60 ° C.

Using the pressure-sensitive adhesive sheet obtained as described above, the gel fraction, haze change, glass foamability, step following ability, ITO resistance change rate, workability and thick coating suitability are evaluated and described in Table 1. To do.
Example 3
In a reactor equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen introduction tube, 93 parts by weight of 2-ethylhexyl acrylate (2EHA), 2 parts by weight of 2-hydroxyethyl acrylate (2-HEA), 5 parts by weight of acrylamide (AM) Parts, 100 parts by weight of ethyl acetate (EtAc) and 20 parts by weight of methyl ethyl ketone (MEK) were added, and the temperature was raised to 63 ° C. while introducing nitrogen gas.

Next, 0.1 part by weight of azobisisobutyronitrile (AIBN) was added, and a polymerization reaction was performed at 70 ° C. for 5 hours in a nitrogen atmosphere.
After completion of the reaction, the mixture was diluted with ethyl acetate (EtAc) and adjusted to a solid content concentration of 30% to obtain an acrylic polymer 3 (polymer 3) having a weight average molecular weight of 350,000. The glass transition temperature (Tg) calculated | required by the formula of Fox about the obtained polymer 3 is -63 degreeC.

  To the polymer 3 obtained as described above, Takenate D-110N (manufactured by Mitsui Chemicals, Inc.) as an isocyanate curing agent was added at a ratio of 0.4 part by weight based on 100 parts by weight of the solid content of the polymer 3. Thus, a pressure-sensitive adhesive composition was obtained (solid content: 30% by weight).

  The obtained pressure-sensitive adhesive composition was applied onto a release-treated polyethylene terephthalate (PET) film to a dry thickness of 50 μm, dried at 80 ° C. for 2 minutes to remove the solvent, The release-treated PET film was bonded to the pressure-sensitive adhesive surface and aged at 23 ° C. for 7 days to obtain a pressure-sensitive adhesive sheet.

  The obtained adhesive sheet was measured for the breaking distance at 23 ° C., 60 ° C. and 80 ° C. according to the method described above. The pressure-sensitive adhesive sheet thus produced has a breaking distance at 23 ° C. of 110 mm, a breaking distance at 60 ° C. of 100 mm, a breaking distance at 80 ° C. of 95 mm, and a breaking distance of 60 ° C. is 91 of the breaking distance of 23 ° C. The breaking distance at 80 ° C. corresponds to 95% of the breaking distance at 60 ° C.

Using the pressure-sensitive adhesive sheet obtained as described above, the gel fraction, haze change, glass foamability, step following ability, ITO resistance change rate, workability and thick coating suitability are evaluated and described in Table 1. To do.
Example 4
In a reactor equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen inlet tube, 91 parts by weight of 2-ethylhexyl acrylate (2EHA), 1 part by weight of 2-hydroxyethyl acrylate (2-HEA), 8 parts by weight of acrylamide (AM) Parts, 100 parts by weight of ethyl acetate (EtAc) and 20 parts by weight of methyl ethyl ketone (MEK) were added, and the temperature was raised to 63 ° C. while introducing nitrogen gas.

Next, 0.1 part by weight of azobisisobutyronitrile (AIBN) was added, and a polymerization reaction was performed at 70 ° C. for 5 hours in a nitrogen atmosphere.
After completion of the reaction, the reaction mixture was diluted with ethyl acetate (EtAc) and adjusted to a solid content concentration of 30% to obtain acrylic polymer 4 (polymer 4) having a weight average molecular weight of 350,000. The glass transition temperature (Tg) calculated | required by the formula of Fox about the obtained polymer 4 is -60 degreeC.

  To the polymer 4 obtained as described above, Takenate D-110N (manufactured by Mitsui Chemicals, Inc.) as an isocyanate curing agent was added at a ratio of 0.4 part by weight with respect to 100 parts by weight of the solid content of the polymer 4. Thus, a pressure-sensitive adhesive composition was obtained (solid content: 30% by weight).

  The obtained pressure-sensitive adhesive composition was applied onto a release-treated polyethylene terephthalate (PET) film to a dry thickness of 50 μm, dried at 80 ° C. for 2 minutes to remove the solvent, The release-treated PET film was bonded to the pressure-sensitive adhesive surface and aged at 23 ° C. for 7 days to obtain a pressure-sensitive adhesive sheet.

  The obtained adhesive sheet was measured for the breaking distance at 23 ° C., 60 ° C. and 80 ° C. according to the method described above. The pressure-sensitive adhesive sheet thus produced has a breaking distance at 23 ° C. of 130 mm, a breaking distance at 60 ° C. of 110 mm, a breaking distance at 80 ° C. of 90 mm, and a breaking distance of 60 ° C. is 85 of the breaking distance of 23 ° C. The breaking distance at 80 ° C. corresponds to 82% of the breaking distance at 60 ° C.

Using the pressure-sensitive adhesive sheet obtained as described above, the gel fraction, haze change, glass foamability, step following ability, ITO resistance change rate, workability and thick coating suitability are evaluated and described in Table 1. To do.
Example 5
In a reaction apparatus equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen introduction tube, 87 parts by weight of 2-ethylhexyl acrylate (2EHA), 5 parts by weight of 2-hydroxyethyl acrylate (2-HEA), 8 parts by weight of acrylamide (AM) Parts, 100 parts by weight of ethyl acetate (EtAc) and 20 parts by weight of methyl ethyl ketone (MEK) were added, and the temperature was raised to 63 ° C. while introducing nitrogen gas.

Next, 0.1 part by weight of azobisisobutyronitrile (AIBN) was added, and a polymerization reaction was performed at 70 ° C. for 5 hours in a nitrogen atmosphere.
After completion of the reaction, the reaction mixture was diluted with ethyl acetate (EtAc) and adjusted to a solid content concentration of 30% to obtain acrylic polymer 5 (polymer 5) having a weight average molecular weight of 350,000. The glass transition temperature (Tg) calculated | required by the formula of Fox about the obtained polymer 5 is -59 degreeC.

  To the polymer 5 obtained as described above, Takenate D-110N (manufactured by Mitsui Chemicals, Inc.) as an isocyanate curing agent was added at a ratio of 0.4 part by weight based on 100 parts by weight of the solid content of the polymer 5. Thus, a pressure-sensitive adhesive composition was obtained (solid content: 30% by weight).

  The obtained pressure-sensitive adhesive composition was applied onto a release-treated polyethylene terephthalate (PET) film to a dry thickness of 50 μm, dried at 80 ° C. for 2 minutes to remove the solvent, The release-treated PET film was bonded to the pressure-sensitive adhesive surface and aged at 23 ° C. for 7 days to obtain a pressure-sensitive adhesive sheet.

  The obtained adhesive sheet was measured for the breaking distance at 23 ° C., 60 ° C. and 80 ° C. according to the method described above. The pressure-sensitive adhesive sheet thus produced has a breaking distance at 23 ° C. of 90 mm, a breaking distance at 60 ° C. of 75 mm, a breaking distance at 80 ° C. of 60 mm, and a breaking distance of 60 ° C. is 83 of the breaking distance of 23 ° C. The break distance at 80 ° C. corresponds to 80% of the break distance at 60 ° C.

Using the pressure-sensitive adhesive sheet obtained as described above, the gel fraction, haze change, glass foamability, step following ability, ITO resistance change rate, workability and thick coating suitability are evaluated and described in Table 1. To do.
Example 6
In a reactor equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen introduction tube, 84 parts by weight of 2-ethylhexyl acrylate (2EHA), 8 parts by weight of 2-hydroxyethyl acrylate (2-HEA), 8 parts by weight of acrylamide (AM) Parts, 100 parts by weight of ethyl acetate (EtAc) and 20 parts by weight of methyl ethyl ketone (MEK) were added, and the temperature was raised to 63 ° C. while introducing nitrogen gas.

Next, 0.1 part by weight of azobisisobutyronitrile (AIBN) was added, and a polymerization reaction was performed at 70 ° C. for 5 hours in a nitrogen atmosphere.
After completion of the reaction, the reaction mixture was diluted with ethyl acetate (EtAc) and adjusted to a solid content concentration of 30% to obtain acrylic polymer 6 (polymer 6) having a weight average molecular weight of 350,000. The glass transition temperature (Tg) calculated | required by the formula of Fox about the obtained polymer 6 is -57 degreeC.

  To the polymer 6 obtained as described above, Takenate D-110N (manufactured by Mitsui Chemicals Co., Ltd.) as an isocyanate curing agent was added at a ratio of 0.4 part by weight relative to 100 parts by weight of the solid content of the polymer 6. Thus, a pressure-sensitive adhesive composition was obtained (solid content: 30% by weight).

  The obtained pressure-sensitive adhesive composition was applied onto a release-treated polyethylene terephthalate (PET) film to a dry thickness of 50 μm, dried at 80 ° C. for 2 minutes to remove the solvent, The release-treated PET film was bonded to the pressure-sensitive adhesive surface and aged at 23 ° C. for 7 days to obtain a pressure-sensitive adhesive sheet.

  The obtained adhesive sheet was measured for the breaking distance at 23 ° C., 60 ° C. and 80 ° C. according to the method described above. The pressure-sensitive adhesive sheet thus produced has a breaking distance at 23 ° C. of 70 mm, a breaking distance at 60 ° C. is 60 mm, a breaking distance at 80 ° C. is 50 mm, and a breaking distance at 60 ° C. is 86 of the breaking distance at 23 ° C. The breaking distance at 80 ° C. corresponds to 83% of the breaking distance at 60 ° C.

Using the pressure-sensitive adhesive sheet obtained as described above, the gel fraction, haze change, glass foamability, step following ability, ITO resistance change rate, workability and thick coating suitability are evaluated and described in Table 1. To do.
Example 7
In a reactor equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen inlet tube, 90 parts by weight of 2-ethylhexyl acrylate (2EHA), 2 parts by weight of 4-hydroxybutyl acrylate (4-HBA), 8 parts by weight of acrylamide (AM) Parts, 100 parts by weight of ethyl acetate (EtAc) and 20 parts by weight of methyl ethyl ketone (MEK) were added, and the temperature was raised to 63 ° C. while introducing nitrogen gas.

Next, 0.1 part by weight of azobisisobutyronitrile (AIBN) was added, and a polymerization reaction was performed at 70 ° C. for 5 hours in a nitrogen atmosphere.
After completion of the reaction, the reaction mixture was diluted with ethyl acetate (EtAc) and adjusted to a solid content concentration of 30% to obtain acrylic polymer 7 (polymer 7) having a weight average molecular weight of 350,000. The glass transition temperature (Tg) calculated | required by the formula of Fox about the obtained polymer 7 is -61 degreeC.

  To the polymer 7 obtained as described above, Takenate D-110N (manufactured by Mitsui Chemicals, Inc.) as an isocyanate curing agent was added at a ratio of 0.4 part by weight based on 100 parts by weight of the solid content of the polymer 7. Thus, a pressure-sensitive adhesive composition was obtained (solid content: 30% by weight).

  The obtained pressure-sensitive adhesive composition was applied onto a release-treated polyethylene terephthalate (PET) film to a dry thickness of 50 μm, dried at 80 ° C. for 2 minutes to remove the solvent, The release-treated PET film was bonded to the pressure-sensitive adhesive surface and aged at 23 ° C. for 7 days to obtain a pressure-sensitive adhesive sheet.

  The obtained adhesive sheet was measured for the breaking distance at 23 ° C., 60 ° C. and 80 ° C. according to the method described above. The pressure-sensitive adhesive sheet thus produced has a breaking distance at 23 ° C. of 100 mm, a breaking distance at 60 ° C. is 90 mm, a breaking distance at 80 ° C. is 70 mm, and a breaking distance at 60 ° C. is 90% of the breaking distance at 23 ° C. %, And the breaking distance at 80 ° C. corresponds to 78% of the breaking distance at 60 ° C.

Using the pressure-sensitive adhesive sheet obtained as described above, the gel fraction, haze change, glass foamability, step following ability, ITO resistance change rate, workability and thick coating suitability are evaluated and described in Table 1. To do.
Example 8
In a reactor equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen introduction tube, 90 parts by weight of 2-ethylhexyl acrylate (2EHA), 2 parts by weight of 2-hydroxyethyl acrylate (2-HEA), 8 parts by weight of acrylamide (AM) And 120 parts by weight of methyl ethyl ketone (MEK) were charged, and the temperature was raised to 63 ° C. while introducing nitrogen gas.

Next, 0.1 part by weight of azobisisobutyronitrile (AIBN) was added, and a polymerization reaction was performed at 70 ° C. for 5 hours in a nitrogen atmosphere.
After completion of the reaction, the reaction mixture was diluted with ethyl acetate (EtAc) and adjusted to a solid content concentration of 30% to obtain acrylic polymer 8 (polymer 8) having a weight average molecular weight of 100,000. The glass transition temperature (Tg) calculated | required by the formula of Fox about the obtained polymer 8 is -60 degreeC.

  To the polymer 8 obtained as described above, Takenate D-110N (manufactured by Mitsui Chemicals, Inc.) as an isocyanate curing agent was added at a ratio of 0.4 part by weight based on 100 parts by weight of the solid content of the polymer 8. Thus, a pressure-sensitive adhesive composition was obtained (solid content: 30% by weight).

  The obtained pressure-sensitive adhesive composition was applied onto a release-treated polyethylene terephthalate (PET) film to a dry thickness of 50 μm, dried at 80 ° C. for 2 minutes to remove the solvent, The release-treated PET film was bonded to the pressure-sensitive adhesive surface and aged at 23 ° C. for 7 days to obtain a pressure-sensitive adhesive sheet.

  The obtained adhesive sheet was measured for the breaking distance at 23 ° C., 60 ° C. and 80 ° C. according to the method described above. The pressure-sensitive adhesive sheet thus produced has a breaking distance at 23 ° C. of 90 mm, a breaking distance at 60 ° C. is 80 mm, a breaking distance at 80 ° C. is 70 mm, and the breaking distance at 60 ° C. is 89% of the breaking distance at 23 ° C. The breaking distance at 80 ° C. corresponds to 88% of the breaking distance at 60 ° C.

Using the pressure-sensitive adhesive sheet obtained as described above, the gel fraction, haze change, glass foamability, step following ability, ITO resistance change rate, workability and thick coating suitability are evaluated and described in Table 1. To do.
Example 9
In a reactor equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen introduction tube, 50 parts by weight of 2-ethylhexyl acrylate (2EHA), 40 parts by weight of lauryl acrylate (LA), 2-hydroxyethyl acrylate (2-HEA) 2 Part by weight, 8 parts by weight of acrylamide (AM), 100 parts by weight of ethyl acetate (EtAc) and 20 parts by weight of methyl ethyl ketone (MEK) were charged, and the temperature was raised to 63 ° C. while introducing nitrogen gas.

Next, 0.1 part by weight of azobisisobutyronitrile (AIBN) was added, and a polymerization reaction was performed at 70 ° C. for 5 hours in a nitrogen atmosphere.
After completion of the reaction, the mixture was diluted with ethyl acetate (EtAc) and adjusted to a solid content concentration of 30% to obtain an acrylic polymer 9 (polymer 9) having a weight average molecular weight of 350,000. The glass transition temperature (Tg) calculated | required by the formula of Fox about the obtained polymer 9 is -35 degreeC.

  To the polymer 9 obtained as described above, Takenate D-110N (manufactured by Mitsui Chemicals Co., Ltd.) as an isocyanate curing agent was added at a ratio of 0.4 part by weight with respect to 100 parts by weight of the solid content of the polymer 9. Thus, a pressure-sensitive adhesive composition was obtained (solid content: 30% by weight).

  The obtained pressure-sensitive adhesive composition was applied onto a release-treated polyethylene terephthalate (PET) film to a dry thickness of 50 μm, dried at 80 ° C. for 2 minutes to remove the solvent, The release-treated PET film was bonded to the pressure-sensitive adhesive surface and aged at 23 ° C. for 7 days to obtain a pressure-sensitive adhesive sheet.

  The obtained adhesive sheet was measured for the breaking distance at 23 ° C., 60 ° C. and 80 ° C. according to the method described above. The pressure-sensitive adhesive sheet thus produced has a breaking distance at 23 ° C. of 100 mm, a breaking distance at 60 ° C. is 90 mm, a breaking distance at 80 ° C. is 70 mm, and a breaking distance at 60 ° C. is 90% of the breaking distance at 23 ° C. %, And the breaking distance at 80 ° C. corresponds to 78% of the breaking distance at 60 ° C.

  Using the pressure-sensitive adhesive sheet obtained as described above, the gel fraction, haze change, glass foamability, step following ability, ITO resistance change rate, workability and thick coating suitability are evaluated and described in Table 1. To do.

〔比較例１〕
攪拌機、環流冷却器、温度計および窒素導入管を備えた反応装置に、２−エチルヘキシルアクリレート（2EHA）８６重量部、2-ヒドロキシエチルアクリレート（2-HEA）２重量部、アクリルアミド（AM）１２重量部および酢酸エチル（EtAc）１００重量部、メチルエチルケトン（MEK）２０重量部を仕込み、窒素ガスを導入しながら６３℃に昇温した。

[Comparative Example 1]
In a reactor equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen introduction tube, 86 parts by weight of 2-ethylhexyl acrylate (2EHA), 2 parts by weight of 2-hydroxyethyl acrylate (2-HEA), 12 parts by weight of acrylamide (AM) Parts, 100 parts by weight of ethyl acetate (EtAc) and 20 parts by weight of methyl ethyl ketone (MEK) were added, and the temperature was raised to 63 ° C. while introducing nitrogen gas.

Next, 0.1 part by weight of azobisisobutyronitrile (AIBN) was added, and a polymerization reaction was performed at 70 ° C. for 5 hours in a nitrogen atmosphere.
After completion of the reaction, the reaction mixture was diluted with ethyl acetate (EtAc) and adjusted to a solid content concentration of 30% to obtain acrylic polymer 10 (polymer 10) having a weight average molecular weight of 350,000. The glass transition temperature (Tg) calculated | required by the formula of Fox about the obtained polymer 10 is -55 degreeC.

  To the polymer 10 obtained as described above, Takenate D-110N (manufactured by Mitsui Chemicals, Inc.) as an isocyanate curing agent was added at a ratio of 0.4 part by weight with respect to 100 parts by weight of the solid content of the polymer 10. Thus, a pressure-sensitive adhesive composition was obtained (solid content: 30% by weight).

  The obtained pressure-sensitive adhesive composition was applied onto a release-treated polyethylene terephthalate (PET) film to a dry thickness of 50 μm, dried at 80 ° C. for 2 minutes to remove the solvent, The release-treated PET film was bonded to the pressure-sensitive adhesive surface and aged at 23 ° C. for 7 days to obtain a pressure-sensitive adhesive sheet.

  The obtained adhesive sheet was measured for the breaking distance at 23 ° C., 60 ° C. and 80 ° C. according to the method described above. The pressure-sensitive adhesive sheet thus produced has a breaking distance at 23 ° C. of 60 mm, a breaking distance at 60 ° C. of 50 mm, a breaking distance at 80 ° C. of 40 mm, and a breaking distance of 60 ° C. is 83 of the breaking distance of 23 ° C. The break distance at 80 ° C. corresponds to 80% of the break distance at 60 ° C.

Using the pressure-sensitive adhesive sheet obtained as described above, the gel fraction, haze change, glass foamability, step following ability, ITO resistance change rate, workability, and thick coating suitability are evaluated and listed in Table 2.
[Comparative Example 2]
In a reactor equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen introduction tube, 97 parts by weight of 2-ethylhexyl acrylate (2EHA), 2 parts by weight of 2-hydroxyethyl acrylate (2-HEA), 1 part by weight of acrylamide (AM) Parts, 100 parts by weight of ethyl acetate (EtAc) and 20 parts by weight of methyl ethyl ketone (MEK) were added, and the temperature was raised to 63 ° C. while introducing nitrogen gas.

Next, 0.1 part by weight of azobisisobutyronitrile (AIBN) was added, and a polymerization reaction was performed at 70 ° C. for 5 hours in a nitrogen atmosphere.
After completion of the reaction, the reaction mixture was diluted with ethyl acetate (EtAc) and adjusted to a solid content concentration of 30% to obtain acrylic polymer 11 (polymer 11) having a weight average molecular weight of 350,000. The glass transition temperature (Tg) calculated | required by the formula of Fox about the obtained polymer 11 is -68 degreeC.

  To the polymer 11 obtained as described above, Takenate D-110N (manufactured by Mitsui Chemicals, Inc.) as an isocyanate curing agent was added at a ratio of 0.4 part by weight with respect to 100 parts by weight of the solid content of the polymer 11. Thus, a pressure-sensitive adhesive composition was obtained (solid content: 30% by weight).

  The obtained pressure-sensitive adhesive composition was applied onto a release-treated polyethylene terephthalate (PET) film to a dry thickness of 50 μm, dried at 80 ° C. for 2 minutes to remove the solvent, The release-treated PET film was bonded to the pressure-sensitive adhesive surface and aged at 23 ° C. for 7 days to obtain a pressure-sensitive adhesive sheet.

  The obtained adhesive sheet was measured for the breaking distance at 23 ° C., 60 ° C. and 80 ° C. according to the method described above. The pressure-sensitive adhesive sheet thus produced has a breaking distance at 23 ° C. of 90 mm, a breaking distance at 60 ° C. is 90 mm, a breaking distance at 80 ° C. is 100 mm, and a breaking distance at 60 ° C. is 100 of the breaking distance at 23 ° C. The breaking distance at 80 ° C. corresponds to 111% of the breaking distance at 60 ° C.

FIG. 8 shows the SS curve of the breaking distance obtained as described above, and Table 2 shows the breaking distance.
In addition, the obtained pressure-sensitive adhesive sheet is evaluated for gel fraction, haze change, foamability against glass, step following ability, ITO resistance change rate, workability and suitability for thick coating, and are shown in Table 2.
[Comparative Example 3]
In a reactor equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen introduction tube, 80 parts by weight of 2-ethylhexyl acrylate (2EHA), 12 parts by weight of 2-hydroxyethyl acrylate (2-HEA), 8 parts by weight of acrylamide (AM) Parts, 100 parts by weight of ethyl acetate (EtAc) and 20 parts by weight of methyl ethyl ketone (MEK) were added, and the temperature was raised to 63 ° C. while introducing nitrogen gas.

Next, 0.1 part by weight of azobisisobutyronitrile (AIBN) was added, and a polymerization reaction was performed at 70 ° C. for 5 hours in a nitrogen atmosphere.
After completion of the reaction, the reaction mixture was diluted with ethyl acetate (EtAc) and adjusted to a solid content concentration of 30% to obtain acrylic polymer 12 (polymer 12) having a weight average molecular weight of 350,000. The glass transition temperature (Tg) calculated | required by the formula of Fox about the obtained polymer 12 is -55 degreeC.

  To the polymer 12 obtained as described above, Takenate D-110N (manufactured by Mitsui Chemicals, Inc.) as an isocyanate curing agent was added at a ratio of 0.4 part by weight with respect to 100 parts by weight of the solid content of polymer 12. Thus, a pressure-sensitive adhesive composition was obtained (solid content: 30% by weight).

  The obtained pressure-sensitive adhesive composition was applied onto a release-treated polyethylene terephthalate (PET) film to a dry thickness of 50 μm, dried at 80 ° C. for 2 minutes to remove the solvent, The release-treated PET film was bonded to the pressure-sensitive adhesive surface and aged at 23 ° C. for 7 days to obtain a pressure-sensitive adhesive sheet.

  The obtained adhesive sheet was measured for the breaking distance at 23 ° C., 60 ° C. and 80 ° C. according to the method described above. The pressure-sensitive adhesive sheet thus produced has a breaking distance at 23 ° C. of 90 mm, a breaking distance at 60 ° C. of 75 mm, a breaking distance at 80 ° C. of 60 mm, and a breaking distance of 60 ° C. is 83 of the breaking distance of 23 ° C. The break distance at 80 ° C. corresponds to 80% of the break distance at 60 ° C.

Using the pressure-sensitive adhesive sheet obtained as described above, the gel fraction, haze change, glass foamability, step following ability, ITO resistance change rate, workability, and thick coating suitability are evaluated and listed in Table 2.
[Comparative Example 4]
In a reactor equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen introduction tube, 90 parts by weight of 2-ethylhexyl acrylate (2EHA), 2 parts by weight of 2-hydroxyethyl acrylate (2-HEA), 8 parts by weight of acrylamide (AM) And 120 parts by weight of ethyl acetate (EtAc) were charged, and the temperature was raised to 63 ° C. while introducing nitrogen gas.

Next, 0.1 part by weight of azobisisobutyronitrile (AIBN) was added, and a polymerization reaction was performed at 70 ° C. for 5 hours in a nitrogen atmosphere.
After completion of the reaction, the reaction mixture was diluted with ethyl acetate (EtAc) and adjusted to a solid content concentration of 30% to obtain acrylic polymer 13 (polymer 13) having a weight average molecular weight of 600,000. The glass transition temperature (Tg) calculated | required by the formula of Fox about the obtained polymer 13 is -60 degreeC.

  To the polymer 13 obtained as described above, Takenate D-110N (manufactured by Mitsui Chemicals, Inc.) as an isocyanate curing agent was added at a ratio of 0.4 part by weight with respect to 100 parts by weight of the solid content of the polymer 13. Thus, a pressure-sensitive adhesive composition was obtained (solid content: 30% by weight).

  The obtained pressure-sensitive adhesive composition was applied onto a release-treated polyethylene terephthalate (PET) film to a dry thickness of 50 μm, dried at 80 ° C. for 2 minutes to remove the solvent, The release-treated PET film was bonded to the pressure-sensitive adhesive surface and aged at 23 ° C. for 7 days to obtain a pressure-sensitive adhesive sheet.

  The obtained adhesive sheet was measured for the breaking distance at 23 ° C., 60 ° C. and 80 ° C. according to the method described above. The pressure-sensitive adhesive sheet thus produced has a breaking distance at 23 ° C. of 100 mm, a breaking distance at 60 ° C. is 90 mm, a breaking distance at 80 ° C. is 70 mm, and a breaking distance at 60 ° C. is 90% of the breaking distance at 23 ° C. %, And the breaking distance at 80 ° C. corresponds to 78% of the breaking distance at 60 ° C.

Using the pressure-sensitive adhesive sheet obtained as described above, the gel fraction, haze change, glass foamability, step following ability, ITO resistance change rate, workability, and thick coating suitability are evaluated and listed in Table 2.
[Comparative Example 5]
In a reactor equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen introduction tube, 90 parts by weight of butyl acrylate (BA), 2 parts by weight of 2-hydroxyethyl acrylate (2-HEA), 8 parts by weight of acrylamide (AM) and 100 parts by weight of ethyl acetate (EtAc) and 20 parts by weight of methyl ethyl ketone (MEK) were charged, and the temperature was raised to 63 ° C. while introducing nitrogen gas.

Next, 0.1 part by weight of azobisisobutyronitrile (AIBN) was added, and a polymerization reaction was performed at 70 ° C. for 5 hours in a nitrogen atmosphere.
After completion of the reaction, the reaction mixture was diluted with ethyl acetate (EtAc) and adjusted to a solid content concentration of 30% to obtain acrylic polymer 14 (polymer 14) having a weight average molecular weight of 350,000. The glass transition temperature (Tg) calculated | required by the formula of Fox about the obtained polymer 14 is -44 degreeC.

  To the polymer 14 obtained as described above, Takenate D-110N (manufactured by Mitsui Chemicals, Inc.) as an isocyanate curing agent was added at a ratio of 0.4 part by weight with respect to 100 parts by weight of the solid content of the polymer 14. Thus, a pressure-sensitive adhesive composition was obtained (solid content: 30% by weight).

  The obtained pressure-sensitive adhesive composition was applied onto a release-treated polyethylene terephthalate (PET) film to a dry thickness of 50 μm, dried at 80 ° C. for 2 minutes to remove the solvent, The release-treated PET film was bonded to the pressure-sensitive adhesive surface and aged at 23 ° C. for 7 days to obtain a pressure-sensitive adhesive sheet.

  The obtained adhesive sheet was measured for the breaking distance at 23 ° C., 60 ° C. and 80 ° C. according to the method described above. The pressure-sensitive adhesive sheet thus produced has a breaking distance at 23 ° C. of 100 mm, a breaking distance at 60 ° C. is 90 mm, a breaking distance at 80 ° C. is 70 mm, and a breaking distance at 60 ° C. is 90% of the breaking distance at 23 ° C. %, And the breaking distance at 80 ° C. corresponds to 78% of the breaking distance at 60 ° C.

Using the pressure-sensitive adhesive sheet obtained as described above, the gel fraction, haze change, glass foamability, step following ability, ITO resistance change rate, workability, and thick coating suitability are evaluated and listed in Table 2.
[Comparative Example 6]
In a reactor equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen introduction tube, 60 parts by weight of butyl acrylate (BA), 30 parts by weight of methyl acrylate (MA), 2 parts by weight of 2-hydroxyethyl acrylate (2-HEA) Then, 8 parts by weight of acrylamide (AM), 100 parts by weight of ethyl acetate (EtAc) and 20 parts by weight of methyl ethyl ketone (MEK) were charged, and the temperature was raised to 63 ° C. while introducing nitrogen gas.

Next, 0.1 part by weight of azobisisobutyronitrile (AIBN) was added, and a polymerization reaction was performed at 70 ° C. for 5 hours in a nitrogen atmosphere.
After completion of the reaction, the reaction mixture was diluted with ethyl acetate (EtAc) and adjusted to a solid content concentration of 30% to obtain acrylic polymer 15 (polymer 15) having a weight average molecular weight of 350,000. The glass transition temperature (Tg) calculated | required by the formula of Fox about the obtained polymer 15 is -27 degreeC.

  To the polymer 15 obtained as described above, Takenate D-110N (manufactured by Mitsui Chemicals, Inc.) as an isocyanate curing agent was added at a ratio of 0.4 part by weight based on 100 parts by weight of the solid content of the polymer 15. Thus, a pressure-sensitive adhesive composition was obtained (solid content: 30% by weight).

  The obtained pressure-sensitive adhesive composition was applied onto a release-treated polyethylene terephthalate (PET) film to a dry thickness of 50 μm, dried at 80 ° C. for 2 minutes to remove the solvent, The release-treated PET film was bonded to the pressure-sensitive adhesive surface and aged at 23 ° C. for 7 days to obtain a pressure-sensitive adhesive sheet.

  The obtained adhesive sheet was measured for the breaking distance at 23 ° C., 60 ° C. and 80 ° C. according to the method described above. The pressure-sensitive adhesive sheet thus produced has a breaking distance at 23 ° C. of 80 mm, a breaking distance at 60 ° C. of 70 mm, a breaking distance at 80 ° C. of 60 mm, and a breaking distance of 60 ° C. is 88 of the breaking distance of 23 ° C. The break distance at 80 ° C. corresponds to 86% of the break distance at 60 ° C.

Using the pressure-sensitive adhesive sheet obtained as described above, the gel fraction, haze change, glass foamability, step following ability, ITO resistance change rate, workability, and thick coating suitability are evaluated and listed in Table 2.
[Comparative Example 7]
In a reaction apparatus equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen introduction tube, 89 parts by weight of 2-ethylhexyl acrylate (2EHA), 2 parts by weight of 2-hydroxyethyl acrylate (2-HEA), 8 parts by weight of acrylamide (AM) Parts, 1 part by weight of acrylic acid (AA), 100 parts by weight of ethyl acetate (EtAc) and 20 parts by weight of methyl ethyl ketone (MEK) were added, and the temperature was raised to 63 ° C. while introducing nitrogen gas.

Next, 0.1 part by weight of azobisisobutyronitrile (AIBN) was added, and a polymerization reaction was performed at 70 ° C. for 5 hours in a nitrogen atmosphere.
After completion of the reaction, the reaction mixture was diluted with ethyl acetate (EtAc) and adjusted to a solid content concentration of 30% to obtain acrylic polymer 16 (polymer 16) having a weight average molecular weight of 350,000. The glass transition temperature (Tg) calculated | required by the formula of Fox about the obtained polymer 16 is -43 degreeC.

  To the polymer 16 obtained as described above, Takenate D-110N (manufactured by Mitsui Chemicals, Inc.) as an isocyanate curing agent was added at a ratio of 0.4 part by weight with respect to 100 parts by weight of the solid content of the polymer 16. Thus, a pressure-sensitive adhesive composition was obtained (solid content: 30% by weight).

  The obtained pressure-sensitive adhesive composition was applied onto a release-treated polyethylene terephthalate (PET) film to a dry thickness of 50 μm, dried at 80 ° C. for 2 minutes to remove the solvent, The release-treated PET film was bonded to the pressure-sensitive adhesive surface and aged at 23 ° C. for 7 days to obtain a pressure-sensitive adhesive sheet.

  The obtained adhesive sheet was measured for the breaking distance at 23 ° C., 60 ° C. and 80 ° C. according to the method described above. The pressure-sensitive adhesive sheet thus produced has a breaking distance at 23 ° C. of 100 mm, a breaking distance at 60 ° C. of 120 mm, a breaking distance at 80 ° C. of 130 mm, and a breaking distance of 60 ° C. is 120 ° of the breaking distance of 23 ° C. %, The break distance at 80 ° C. corresponds to 108% of the break distance at 60 ° C.

  Using the pressure-sensitive adhesive sheet obtained as described above, the gel fraction, haze change, glass foamability, step following ability, ITO resistance change rate, workability, and thick coating suitability are evaluated and listed in Table 2.

比較例１は粘着シートを製造する際にアクリルアミドを１２重量部使用しており、アクリルアミドから誘導される繰返し単位が過剰になり発泡が生ずる。比較例２は窒素含有モノマーであるアクリルアミドを１重量部使用しており、疑似架橋構造の形成が充分でないため破断距離は高温で大きくなっている。比較例４は、重量平均分子量が６０万であることから、塗工液の粘度が高くなり厚塗り適性が劣ると共に段差追従性が劣る。比較例７はアクリル酸を共重合したことにより粘着シートが酸性基を有することになりＩＴＯ電極に腐蝕が発生氏ＩＴＯ抵抗変化が大きい。

In Comparative Example 1, 12 parts by weight of acrylamide is used when producing the pressure-sensitive adhesive sheet, and the repeating unit derived from acrylamide becomes excessive and foaming occurs. Comparative Example 2 uses 1 part by weight of acrylamide, which is a nitrogen-containing monomer, and the formation of a pseudo-crosslinked structure is not sufficient, so that the breaking distance increases at high temperatures. Since the comparative example 4 has a weight average molecular weight of 600,000, the viscosity of the coating liquid becomes high, and the suitability for thick coating is inferior and the step following ability is inferior. In Comparative Example 7, the pressure-sensitive adhesive sheet has an acidic group due to copolymerization of acrylic acid, and the ITO electrode is corroded, resulting in a large change in ITO resistance.

10-1 ... resistive film type touch panel unit 10-2 ... capacitive touch panel unit 11-1 ... upper laminate 13-1 ... lower laminate 15-1 ... upper part Laminate 15-2 ... Lower laminate 21-1 ... Surface support 21-2 ... Deep surface support 23-1 ... Adhesive layer 23-2 ... Adhesive layer 25 -1 ... Upper electrode support 25-2 ... Lower electrode support 27-1 ... Transparent conductive film 27-2 ... Transparent conductive film 30 ... Bonding agent 32 ... Spacer 34 ... Gap 51-1 ... Surface support 51-2 ... Surface support 53-1 ... Adhesive layer 57-1 ... Transparent conductive film 57-2 ... Transparent conductive film 60 ... Center support 62 ... Frame printing part 64 ... Gap 66 ... Bubble 68 ... Bubble

Claims (8)

The following components (a-1) to (a-4)
(a-1) alkyl (meth) acrylate having 8 to 18 carbon atoms in the alkyl group
80 to 93% by weight ,
(a-2) 1 to 5% by weight of a hydroxyl group-containing monomer,
(a-3) 6-9% by weight of nitrogen-containing monomer and
(a-4) Other monomers containing 0 to 13% by weight of acrylic acid ester (the total of the above components (a-1) to (a-4) is 100% by weight) are copolymerized in the presence of an organic solvent. Forming an acrylic polymer (A) solution having a weight average molecular weight of substantially 50,000 or more and less than 400,000, which has substantially no acidic group.
The isocyanate-based crosslinking agent (B) is used in the acrylic polymer (A) solution in an amount within the range of 0.1 to 30 parts by weight with respect to 100 parts by weight of the solid content in the acrylic polymer (A) solution. the crosslinked structure is formed Te, the isocyanate the acrylic polymer cross-linked structure is formed by a crosslinking agent (a) solution was cast, with the production of pressure-sensitive adhesive sheet to remove the solvent and formed from the PSA sheet A pressure-sensitive adhesive sheet test piece having a thickness of 200 μm and a width of 10 mm is formed by forming a pseudo-crosslinked structure so that the breaking distance of the tensile test at each temperature is gradually shortened as the measurement temperature is increased at a speed of 100 mm / min. A method for producing an adhesive sheet. The pressure-sensitive adhesive sheet has a breaking distance at 23 ° C. in the range of 150 to 50 mm, a breaking distance at 60 ° C. in the range of 143 to 40 mm, a breaking distance at 80 ° C. in the range of 136 to 30 mm, The method for producing a pressure-sensitive adhesive sheet according to claim 1, wherein the crosslinked structure is formed so that the breaking distances at 23 ° C, 60 ° C and 80 ° C have a relationship represented by the following formula (1):
23 ° C. breaking distance> 60 ° C. breaking distance> 80 ° C. breaking distance (1)   The breaking distance at 60 ° C. is in the range of 50 to 95% of the breaking distance at 23 ° C., and the breaking distance at 80 ° C. is in the range of 30 to 95% of the breaking distance at 60 ° C. The method for producing a pressure-sensitive adhesive sheet according to claim 2.   The method for producing a pressure-sensitive adhesive tape according to claim 1, wherein the pressure-sensitive adhesive sheet is a pressure-sensitive adhesive sheet for a capacitive touch panel in direct contact with a metal or metal oxide. The following components (a-1) to (a-4)
(a-1) alkyl (meth) acrylate having 8 to 18 carbon atoms in the alkyl group
80 to 93% by weight ,
(a-2) 1 to 5% by weight of a hydroxyl group-containing monomer,
(a-3) 6-9% by weight of nitrogen-containing monomer and
(a-4) Other monomers containing 0 to 13% by weight of acrylic acid ester (the total of the above components (a-1) to (a-4) is 100% by weight) are copolymerized in the presence of an organic solvent. Forming an acrylic polymer (A) solution having a weight average molecular weight of substantially 50,000 or more and less than 400,000, which has substantially no acidic group.
The isocyanate-based crosslinking agent (B) is used in the acrylic polymer (A) solution in an amount within the range of 0.1 to 30 parts by weight with respect to 100 parts by weight of the solid content in the acrylic polymer (A) solution. the crosslinked structure is formed Te, the isocyanate the acrylic polymer cross-linked structure is formed by a crosslinking agent (a) solution was cast, with the production of pressure-sensitive adhesive sheet to remove the solvent and formed from the PSA sheet A pressure-sensitive adhesive sheet in which a pseudo-crosslinked structure is formed so that the breaking distance of a tensile test at each temperature under a speed condition of 100 mm / min for a pressure-sensitive adhesive sheet test piece having a thickness of 200 μm and a width of 10 mm gradually decreases as the measurement temperature increases. A method for producing a laminate for a touch panel, comprising: attaching a transparent substrate and an electrode. The pressure-sensitive adhesive sheet has a breaking distance at 23 ° C. in the range of 150 to 50 mm, a breaking distance at 60 ° C. in the range of 143 to 40 mm, a breaking distance at 80 ° C. in the range of 136 to 30 mm, The method for producing a laminate for a touch panel according to claim 5, wherein the crosslinked structure is formed so that the breaking distances at 23 ° C, 60 ° C, and 80 ° C have a relationship represented by the following formula (1): ;
23 ° C. breaking distance> 60 ° C. breaking distance> 80 ° C. breaking distance (1)   The breaking distance at 60 ° C. is in the range of 50 to 95% of the breaking distance at 23 ° C., and the breaking distance at 80 ° C. is in the range of 50 to 95% of the breaking distance at 60 ° C. The manufacturing method of the laminated body for touchscreens of Claim 6.   6. The method for producing a laminate for a touch panel according to claim 5, wherein the pressure-sensitive adhesive sheet is a pressure-sensitive adhesive sheet for a capacitive touch panel that is in direct contact with a metal or a metal oxide.

Images