KR20170018769A - Adhesive sheet and display - Google Patents

Abstract

Provided are an adhesive sheet capable of exhibiting high strength in coating films as well as outstanding stepped pulley following properties when applied in an adhesive layer, and a display object. To this end, the adhesive sheet (1) comprises: a single display object constitution member having a stepped pulley on a fused side at least; and the adhesive layer (11) for fusing another display object constitution member. When tensile strength of an adhesive making up the adhesive layer (11) is tested at 23 deg. C, the adhesive sheet (1) has shown at least 0.22 MPa of modulus and 30% stepped pulley following ratio in the adhesive layer (11) at a point when the adhesive is fractured before reaching 1000% modulus or 1000% elongation rates.

Description

ADHESIVE SHEET AND DISPLAY [0002]

The present invention relates to a pressure-sensitive adhesive sheet suitable for bonding a display body constituting member and a display body obtained by using the pressure-sensitive adhesive sheet.

2. Description of the Related Art Various mobile electronic devices such as smart phones and tablet terminals in recent years are equipped with a display using a display module having a liquid crystal element, a light emitting diode (LED element), an organic electroluminescence (organic EL) The display becomes a touch panel.

In the above-described display, a protective panel is usually provided on the surface side of the display module. With the thinning and lightening of electronic devices, the protective panel is changed from a conventional glass plate to a plastic plate such as an acrylic plate or a polycarbonate plate.

Between the protective panel and the display body module, a gap is formed so that the deformed protective panel does not hit the display body module even when the protective panel is deformed by an external force.

However, when such air gaps are present, there is a problem that the reflection loss of light due to the refractive index difference between the protective panel and the air layer and the refractive index difference between the air layer and the display module is large, and the image quality of the display is deteriorated.

Therefore, it has been proposed to improve the image quality of the display by embedding voids between the protective panel and the display module with a pressure-sensitive adhesive layer. However, on the display body module side of the protective panel, the printed layer on the frame may exist as a step. If the pressure-sensitive adhesive layer does not follow the step, the pressure-sensitive adhesive layer is excited near the step, thereby causing reflection loss of light. Therefore, the pressure-sensitive adhesive layer is required to follow the step.

In order to solve the above problems, Patent Document 1 discloses a pressure-sensitive adhesive layer for embedding voids between a protective panel and a display module, wherein the shear storage modulus (G ') at 25 ° C and 1 Hz is 1.0 × 10 ⁵ Pa or less , And a pressure-sensitive adhesive layer having a gel fraction of 40% or more.

Japanese Patent Application Laid-Open No. 2010-97070

Patent Document 1 attempts to improve the step-wise followability by lowering the storage modulus at room temperature in the pressure-sensitive adhesive layer. However, if the storage elastic modulus is lowered as such, the film strength of the pressure-sensitive adhesive layer is lowered and the processability is deteriorated. For example, when the pressure sensitive adhesive sheet is subjected to punch processing, a problem occurs that a pressure sensitive adhesive is adhered to the blade and a part of the pressure sensitive adhesive layer is removed. Further, when the pressure-sensitive adhesive sheet is stored, there is a problem that the pressure-sensitive adhesive layer seeps out from the pressure-sensitive adhesive layer.

It is an object of the present invention to provide a pressure-sensitive adhesive sheet and a pressure-sensitive adhesive sheet which can exert a high film strength while exhibiting excellent step-wise followability.

In order to achieve the above object, the present invention provides, firstly, a pressure-sensitive adhesive sheet having one display body constituting member having a step on a surface to be at least on the side to be conjugated, and a pressure-sensitive adhesive layer for bonding other display body constituting members, When the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is subjected to a tensile test at 23 占 폚, the modulus at break when the pressure-sensitive adhesive is broken before reaching 1000% modulus of the pressure-sensitive adhesive or the elongation percentage of 1000% is 0.22 MPa or more, Wherein the layer following step following rate is 30% or more (Invention 1).

The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet according to the invention (Invention 1) can exhibit high film strength as well as superior step-wise followability.

In the above invention (Invention 1), the tensile elongation when the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is subjected to tensile test at 23 캜 is preferably 500% or more (Invention 2).

In the above invention (Invention 1 or 2), the haze value of the pressure-sensitive adhesive layer is preferably 5% or less (Invention 3).

In the above invention (inventions 1 to 3), it is preferable that the pressure-sensitive adhesive sheet has two release sheets, and the pressure-sensitive adhesive layer is sandwiched between the release sheets so as to contact the release surfaces of the two release sheets (Invention 4).

Secondly, the present invention provides a display device comprising: a display body constructing member having at least a step on a side to be conjugated; another display body constructing member; and a second display body constructing member A display body provided with a pressure-sensitive adhesive layer, wherein the pressure-sensitive adhesive layer is a pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet (invention 1 to 4).

The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet and the display body according to the present invention can exhibit high film strength as well as excellent step-wise followability.

1 is a cross-sectional view of a pressure-sensitive adhesive sheet according to an embodiment of the present invention.
2 is a cross-sectional view of a laminate according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described.

[Adhesive sheet]

The pressure-sensitive adhesive sheet according to the embodiment of the present invention has one display member constituting member having a step on a surface to be at least on the side to be conjugated and a pressure-sensitive adhesive layer for bonding other display member constituent members. The display body and the display body constituting member will be described later.

1. Properties

(1) Modulus

When the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer was subjected to a tensile test at 23 ° C, the modulus at 1000% of the pressure-sensitive adhesive (when the pressure-sensitive adhesive was broken before reaching the elongation percentage of 1000%, the modulus at break was simply referred to as "modulus at break" ) Is not less than 0.22 MPa, preferably not less than 0.25 MPa, and particularly preferably not less than 0.27 MPa. Since the lower limit value of the 1000% modulus (or modulus at break) is 0.22 MPa or more, the film strength as a pressure-sensitive adhesive layer is high and workability is excellent. For example, when the pressure-sensitive adhesive sheet is subjected to punch machining, the problem that the pressure sensitive adhesive is adhered to the blade and part of the pressure-sensitive adhesive layer is removed is prevented from occurring. In addition, when the pressure sensitive adhesive sheet is stored, the pressure sensitive adhesive is prevented from leaking out from the pressure sensitive adhesive layer.

The upper limit value of the 1000% modulus (or modulus at break) is not particularly limited, but is preferably 2.0 MPa or lower, more preferably 1.0 MPa or lower, and is preferably 0.5 MPa or less Is more preferable. Here, the details of the tensile test are as shown in the following test examples.

(2) Step followability

The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet according to the present embodiment has a stepwise follow-up rate (%) represented by the following formula as a lower limit value of 30% or more, preferably 40% or more, and particularly preferably 50% or more. On the other hand, the upper limit value of the step following rate is not particularly limited, but is usually 80% or less, and particularly preferably 70% or less.

(%) = {(Height of stepped portion without bubble, lifting, peeling, etc. after the predetermined durability test and maintained in the embedded state) / (thickness of pressure-sensitive adhesive layer)} x 100

The predetermined durability test is a test in which the sample is stored at 85 캜 and 85% RH for 72 hours, and a specific test method of the step followability rate is as shown in the following test examples.

When the pressure sensitive adhesive sheet according to the present embodiment is attached to the display body constituting member having a step difference, the pressure sensitive adhesive layer is easily followed to the step because the step following rate of the pressure sensitive adhesive layer is in the above range, Is suppressed. In addition, even when it is left under such conditions of high temperature and high humidity, for example, under the conditions of 85 ° C and 85% RH for 72 hours, bubbling, lifting, peeling and the like are prevented from occurring near the step. Thereby, reflection loss of light is suppressed in the obtained display body.

As described above, the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet according to the present embodiment combines the contradictory physical properties of high film strength and excellent step-following property.

(3)

The tensile elongation of the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer when subjected to a tensile test at 23 캜 is preferably 500% or more, more preferably 800% or more, further preferably 1000% or more, Is most preferable. Since the elongation at break is 500% or more, the pressure-sensitive adhesive layer can easily satisfy the step-following response rate.

The upper limit of the elongation at break is not particularly limited, but is usually preferably not more than 3000%, more preferably not more than 2000%. Here, the tensile test of the elongation at break is performed by the same method as the tensile test of 1000% modulus (or modulus at break) described above.

(4) Adhesion

The adhesive strength of the pressure-sensitive adhesive sheet according to the present embodiment to soda lime glass is preferably 5 N / 25 mm or more as the lower limit value, more preferably 10 N / 25 mm or more, and further preferably 15 N / 25 mm or more. If the adhesive force of the pressure-sensitive adhesive sheet 1 is 5 N / 25 mm or more, the step following property under high temperature and high humidity becomes more excellent. The adhesive strength of the pressure-sensitive adhesive sheet according to the present embodiment to soda lime glass is preferably 50 N / 25 mm or less, more preferably 40 N / 25 mm or less, particularly preferably 35 N / 25 mm or less, / 25 mm or less. When the adhesive force of the adhesive sheet 1 is 50 N / 25 mm or less, adhesion of the adhesive to the blade at the time of cutting can be prevented. When the adhesive force is 25 N / 25 mm or less, good reworkability is obtained, It is possible to reuse expensive display member constituting members.

The adhesive force is basically the adhesive force measured by the 180 degree peeling method in accordance with JIS Z0237: 2009, but the measurement sample is set to have a width of 25 mm and a length of 100 mm, the measurement sample is attached to an adherend, 0.5 MPa and pressurized at 50 캜 for 20 minutes and then left at normal pressure, 23 캜 and 50% RH for 24 hours, and then measured at a peeling rate of 300 mm / min.

(5) wet heat adhesion

The adhesive force (hereinafter referred to as " wet heat adhesion force " in the present specification) of soda lime glass of the pressure-sensitive adhesive sheet according to the present embodiment is preferably 5 N / 25 mm or more as the lower limit value, more preferably 10 N / And more preferably 15 N / 25 mm or more. When the adhesive sheet 1 has a wet heat adhesive strength of 5 N / 25 mm or more, the step following property under high temperature and high humidity is more excellent. The upper limit of the adhesive strength of the adhesive sheet to the soda lime glass according to the present embodiment is preferably 50 N / 25 mm or less, more preferably 40 N / 25 mm or less, particularly preferably 30 N / More preferably 25 N / 25 mm or less. If the adhesive force of the adhesive sheet 1 is not more than 50 N / 25 mm, the adhesive can be prevented from adhering to the blade at the time of cutting, and if it is 25 N / 25 mm or less, good reworkability can be obtained, It is possible to reuse the display member constituting member at an expensive price.

Here, the above-mentioned wet heat adhesion is basically the adhesive force measured by the 180 degree peeling method according to JIS Z0237: 2009, but the measurement sample is set to have a width of 25 mm and a length of 100 mm, and the measurement sample is affixed to an adherend , The pressure was kept at 0.5 MPa and 50 캜 for 20 minutes and then allowed to stand for 24 hours under the conditions of 60 캜 and 90% RH. Subsequently, the substrate was left under the conditions of normal pressure, 23 캜 and 50% RH for 24 hours, min. < / RTI >

(6) Haze value

The haze value of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet according to the present embodiment is preferably 5% or less, more preferably 3% or less, particularly preferably 1% or less, further preferably 0.7% or less. If the haze value of the pressure-sensitive adhesive layer is 5% or less, the transparency is extremely high and is preferable for optical use (for a display). The haze value in this specification is a value measured in accordance with JIS K7136: 2000.

2. Adhesive layer

The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet according to the present embodiment satisfies the above-mentioned 1000% modulus (or modulus at break) and step following property, and preferably further satisfies the above-described elongation at break, adhesive force, As shown in Fig.

Such a pressure-sensitive adhesive is preferably a (meth) acrylic acid ester polymer containing a monomer having a hydroxyl group (a monomer containing a hydroxyl group in the molecule) and an alicyclic structure-containing monomer (a monomer containing an alicyclic structure in the molecule) (Hereinafter also referred to as " sticky composition P ") containing a cyclic oligosaccharide (A), a cyclic oligosaccharide-containing polyrotaxane compound (B) and an isocyanate cross-linking agent (C) Can be obtained. However, the present invention is not limited to this.

In the present specification, (meth) acrylic acid means both acrylic acid and methacrylic acid. The same is true of other similar terms. The term " polymer " includes the concept of " copolymer ".

When the adhesive composition P is crosslinked, the hydroxyl group derived from the hydroxyl group-containing monomer in the (meth) acrylic acid ester polymer (A) reacts with the isocyanate group of the isocyanate crosslinking agent (C) to form a three-dimensional network structure, Is obtained. The polyrotaxane compound (B) has a mechanical bond between a cyclic molecule and a linear molecule passing therethrough, and the cyclic molecule is allowed to move freely in a linear molecular phase. With this structure, the polyrotaxane compound (B) can impart excellent stress relaxation property to the resulting pressure-sensitive adhesive. Further, since the alicyclic structure-containing monomer has a large volume, it is presumed that the presence of the alicyclic structure monomer in the polymer widens the interval between the polymers, and the resulting pressure-sensitive adhesive can be made excellent in flexibility. Accordingly, when the pressure-sensitive adhesive composition P contains the polyrotaxane compound (B) and the (meth) acrylic acid ester polymer (A) has the alicyclic structure-containing monomer as a constituent monomer unit, , The step following ability is excellent, and the value of the step following ability can be satisfied.

Since the excellent step-following property can be obtained without lowering the storage modulus of the pressure-sensitive adhesive, the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive obtained by crosslinking the pressure-sensitive adhesive composition P can exhibit high film strength, Modulus) can be satisfied.

When the cyclic oligomer of the polyrotaxane compound (B) is a cyclic oligosaccharide having a hydroxyl group as a reactive group, the following actions and effects are particularly exhibited. That is, when the adhesive composition P is crosslinked, the isocyanate group of the isocyanate crosslinking agent (C) reacts with the hydroxyl group derived from the hydroxyl group-containing monomer in the (meth) acrylic acid ester polymer (A) The isocyanate group reacts with the hydroxyl group of the cyclic molecule of the polyrotaxane compound (B). Thereby, the (meth) acrylic acid ester polymer (A) is bonded to one cyclic molecule of the polyrotaxane compound (B) via the isocyanate crosslinking agent (C) by the hydroxyl group and likewise, the other (meth) acrylic acid ester It is presumed that the polymer (A) binds with other cyclic molecules of the polyrotaxane compound (B). As a result, it is presumed that the plurality of (meth) acrylic acid ester polymers (A) form a higher-order structure such as a three-dimensional network structure mechanically bonded to each other by the polyrotaxane compound (B). By such a higher order structure, it is possible to make the film strength higher, as compared with the same higher order structure, except that the polyrotaxane compound (B) is not provided, without deteriorating the stress relaxation property (the step traceability remains intact).

It is not necessary that all of the obtained pressure sensitive adhesive is the above estimated structure and that the two (meth) acrylic acid ester polymers (A) are directly bonded by the isocyanate crosslinking agent (C) without interposing the polyrotaxane compound (B) And the like.

(1) (Meth) acrylic acid ester polymer (A)

The (meth) acrylic acid ester polymer (A) preferably contains a monomer containing a hydroxyl group and a monomer containing an alicyclic structure as a monomer unit constituting the polymer.

Examples of the hydroxyl group-containing monomer include (meth) acrylic acid 2-hydroxyethyl, (meth) acrylic acid 2-hydroxypropyl, (meth) acrylic acid 3-hydroxypropyl, (meth) acrylic acid 2-hydroxybutyl, (Meth) acrylic acid hydroxyalkyl esters such as 3-hydroxybutyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate. Among them, 2-hydroxyethyl (meth) acrylate or (meth) acrylic acid (meth) acrylate is preferable from the viewpoints of reactivity with the isocyanate crosslinking agent (C) of the hydroxyl group in the resultant (meth) acrylic acid ester polymer 4-Hydroxybutyl is preferred. These may be used alone or in combination of two or more.

The (meth) acrylic acid ester polymer (A) preferably contains 3% by mass or more, particularly preferably 5% by mass or more, of the hydroxyl group-containing monomer as the lower limit value as the monomer unit constituting the polymer, and more preferably 10% By mass or more. When the content of the hydroxyl group-containing monomer is 3% by mass or more, the cohesive force of the obtained pressure-sensitive adhesive is improved, whereby the film strength becomes higher. The (meth) acrylic acid ester polymer (A) preferably contains a hydroxyl group-containing monomer as an upper limit of 30 mass% or less, more preferably 25 mass% or less as the monomer unit constituting the polymer, Is preferably contained in an amount of 20 mass% or less. When the content of the hydroxyl group-containing monomer is 30 mass% or less, it is easy to obtain an appropriate tackiness, and the tackiness of the pressure-sensitive adhesive is prevented from being too hard, and the step traceability is further improved.

The carbon ring of the alicyclic structure in the alicyclic structure-containing monomer may have a saturated structure or may have an unsaturated bond in a part thereof. The alicyclic structure may be a monocyclic alicyclic structure or a polycyclic alicyclic structure such as a bicyclic or tricyclic ring. From the viewpoint of making the mutual distances between the obtained (meth) acrylic acid ester copolymer (A) appropriate and giving higher stress relaxation property to the pressure-sensitive adhesive, the alicyclic structure is a polycyclic alicyclic structure (polycyclic structure) desirable. In consideration of the compatibility of the (meth) acrylic acid ester copolymer (A) with other components, the polycyclic structure is particularly preferably a divalent to tetravalent ring. In addition, from the viewpoint of imparting stress relaxation property as described above, the number of carbon atoms of the alicyclic structure (the total number of carbon atoms in the part forming the ring, and when plural rings are present independently, the total number of carbon atoms) It is generally preferably 5 or more, and particularly preferably 7 or more. On the other hand, the upper limit of the carbon number of the alicyclic structure is not particularly limited, but from the viewpoint of compatibility as described above, it is preferably 15 or less, and particularly preferably 10 or less.

Specific examples of the alicyclic structure-containing monomer include cyclohexyl (meth) acrylate, dicyclopentyl (meth) acrylate, adamantyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentenyl And dicyclopentenyloxyethyl (meth) acrylate. Of these, dicyclopentanyl (meth) acrylate (the number of carbon atoms in the alicyclic structure is 10), (meth) acrylic acid Adamantyl (the number of carbon atoms of the alicyclic structure: 10) or isobornyl (meth) acrylate (the number of carbon atoms of the alicyclic structure: 7) is preferable, and isobornyl (meth) acrylate is particularly preferable. These may be used singly or in combination of two or more kinds.

The (meth) acrylic acid ester polymer (A) preferably contains 1% by mass or more, particularly preferably 5% by mass or more, of the monomer unit containing the alicyclic structure as the monomer unit constituting the polymer, and more preferably 10% By mass or more. The (meth) acrylic acid ester polymer (A) preferably contains 50% by mass or less, more preferably 40% by mass or less, of the monomer unit containing the alicyclic structure as the monomer unit constituting the polymer, Is preferably contained in an amount of 30 mass% or less. When the content of the alicyclic structure-containing monomer is within the above range, the resulting pressure sensitive adhesive exhibits excellent step-wise followability and exhibits excellent adhesive strength to the transparent conductive film and plastic.

(Meth) acrylic acid ester polymer (A) is a monomer unit constituting the polymer, in addition to the monomer containing a hydroxyl group and the monomer containing an alicyclic structure, alkyl (meth) acrylate having an alkyl group of 5 to 20, especially 8 to 15, It is preferable to contain an ester (not including an alicyclic structure). This makes it possible to exhibit favorable tackiness without lowering the compatibility with the polyrotaxane compound (B). In addition, flexibility is imparted to the obtained pressure-sensitive adhesive, so that excellent step-following ability can be obtained. The alkyl group may be either straight chain or branched chain.

In view of the above, it is preferable that the (meth) acrylic acid ester polymer (A) contains 10 mass% or more of a (meth) acrylic acid alkyl ester having 5 to 20 carbon atoms in the alkyl group as the monomer unit constituting the polymer, More preferably 20 mass% or more, further preferably 50 mass% or more. When the above-mentioned (meth) acrylic acid alkyl ester is contained in an amount of 10 mass% or more, the obtained pressure-sensitive adhesive can exhibit favorable tackiness and superior step-like followability. The (meth) acrylic acid ester polymer (A) preferably contains 90 mass% or less of a (meth) acrylic acid alkyl ester having 5 to 20 carbon atoms in the alkyl group as the monomer unit constituting the polymer, By mass or less, more preferably 70% by mass or less. When the amount of the (meth) acrylic acid alkyl ester is 90% by mass or less, other monomer components can be preferably introduced into the (meth) acrylic acid ester polymer (A).

Examples of the (meth) acrylic acid alkyl ester having 5 to 20 carbon atoms in the alkyl group include n-pentyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) , N-decyl (meth) acrylate, n-dodecyl (meth) acrylate, myristyl (meth) acrylate and palmityl (meth) acrylate. Among them, 2-ethylhexyl (meth) acrylate is preferable from the standpoint of adhesiveness and compatibility with the polyrotaxane compound (B). These may be used alone or in combination of two or more.

On the other hand, the (meth) acrylic acid ester polymer (A) contains no (meth) acrylic acid alkyl ester having an alkyl group having 4 or less carbon atoms, or less than 60 mass%, preferably 50 mass% By mass or less, particularly preferably 30% by mass or less. As a result, other monomer components can be preferably introduced into the (meth) acrylic acid ester polymer (A) in a preferable amount.

It is also preferable that the (meth) acrylic acid ester polymer (A) contains a nitrogen atom-containing monomer as a monomer unit constituting the polymer. By having the nitrogen atom-containing monomer as a constituent unit in the polymer, a predetermined polarity is given to the pressure-sensitive adhesive, and the affinity to an adherend having a certain polarity such as glass can be made excellent. Examples of the nitrogen atom-containing monomer include monomers having an amino group, monomers having an amide group, monomers having a nitrogen-containing heterocyclic ring, and the like. Among them, from the viewpoint of imparting appropriate rigidity to the (meth) acrylic acid ester polymer (A) Monomers having a nitrogen-containing heterocycle are preferred.

Examples of the monomer having a nitrogen-containing heterocyclic ring include N- (meth) acryloylmorpholine, N- vinyl-2-pyrrolidone, N- (meth) acryloylpyrrolidone, N- (Meth) acryloylpyridine, N- (meth) acryloylpyrrolidine, N- (meth) acryloyl aziridine, aziridinyl ethyl (meth) acrylate, 2- vinylpyridine, Vinylimidazole, N-vinylcarbazole, N-vinylphthalimide and the like. Among them, N- (meth) acryloylmorpholine which exhibits more excellent adhesive strength is preferable, and in particular, N-acryloylmorpholines are preferred.

(Meth) acrylamide, N-methyl (meth) acrylamide, N-methylol (meth) acrylamide, N-tert- butyl (Meth) acrylamide, N, N-ethyl (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, N-isopropyl , (Meth) acrylamide, N-vinylcaprolactam, monomethylaminoethyl (meth) acrylate, monoethylaminoethyl (meth) acrylate, monomethylaminopropyl (meth) acrylate, monoethylamino Propyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, and the like.

These nitrogen atom-containing monomers may be used singly or in combination of two or more species.

When the (meth) acrylic acid ester polymer (A) contains a nitrogen atom-containing monomer as a monomer unit constituting the polymer, it preferably contains 0.5% by mass or more of the nitrogen atom-containing monomer, more preferably 1% By mass, more preferably 3% by mass or more. The (meth) acrylic acid ester polymer (A) preferably contains 20 mass% or less of the nitrogen atom-containing monomer as the monomer unit constituting the polymer, more preferably 15 mass% or less, Is preferably contained in an amount of 8 mass% or less. When the content of the nitrogen atom-containing monomer is within the above range, the obtained pressure-sensitive adhesive can sufficiently exert an excellent adhesive force to glass.

It is also preferable that the (meth) acrylic acid ester polymer (A) contains a hard monomer having a glass transition temperature (Tg) of 0 ° C or more as a homopolymer as a monomer unit constituting the polymer. The hard monomer may also include the various monomers described above. By containing the above-mentioned hard monomer as a monomer unit constituting the (meth) acrylic acid ester polymer (A), the resulting pressure sensitive adhesive exhibits improved cohesion and higher film strength. Particularly when (meth) acrylic acid alkyl ester (for example, (meth) acrylate 2-ethylhexyl) having an alkyl group of 5 to 20 carbon atoms is used as the monomer unit constituting the (meth) acrylic acid ester polymer , It is preferable to use the hard monomer because the cohesive force tends to be lowered. The glass transition temperature (Tg) of the hard monomer as the homopolymer is preferably 15 ° C or more as a lower limit value, and more preferably 80 ° C or more. The upper limit of the glass transition temperature (Tg) is preferably 200 占 폚 or lower, more preferably 180 占 폚 or lower.

Examples of the hard monomer include methyl acrylate (Tg 10 ° C), methyl methacrylate (Tg 105 ° C), isobornyl acrylate (Tg 94 ° C), isobornyl methacrylate (Tg 180 ° C) (Tg 115 ° C), adamantyl methacrylate (Tg 141 ° C), acryloylmorpholine (Tg 145 ° C), and cyclohexyl acrylate (Tg 19 ° C). These may be used alone or in combination of two or more.

When the (meth) acrylic acid ester polymer (A) contains the hard monomer as the monomer unit constituting the polymer, it preferably contains the hard monomer in an amount of 5 mass% or more, particularly preferably 10 mass% or more Do. By containing not less than 5 mass% of the hard monomer, the film strength can be further improved. The (meth) acrylic acid ester polymer (A) preferably contains the hard monomer in an amount of 40 mass% or less, particularly preferably 30 mass% or less, as the monomer unit constituting the polymer. By setting the content of the hard monomer to 40 mass% or less, it is possible to prevent the relative shortage of other monomer units in the (meth) acrylic acid ester polymer (A), and to obtain excellent tackiness and step traceability of the resulting pressure- .

The (meth) acrylic acid ester polymer (A) may contain other monomer as a monomer unit constituting the polymer as desired. The other monomer may be a monomer containing a reactive functional group (excluding a hydroxyl group), or may be a monomer containing no reactive functional group.

As the monomer containing a reactive functional group, a carboxyl group-containing monomer can be preferably exemplified. Examples of the carboxyl group-containing monomer include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid and citraconic acid. Among them, acrylic acid is preferable from the viewpoint of the effect of the reaction between the hydroxyl group derived from the hydroxyl group-containing monomer and the isocyanate cross-linking agent (C) and the copolymerization with other monomers. These may be used alone or in combination of two or more.

When the (meth) acrylic acid ester polymer (A) contains a monomer having a carboxyl group as a monomer unit constituting the polymer, the content thereof is preferably 0.5% by mass or more, particularly preferably 1% by mass or more. The upper limit value is preferably 20 mass% or less, more preferably 10 mass% or less.

Also, from the viewpoint of facilitating control of the cross-linking structure of the obtained pressure-sensitive adhesive, it is also preferable to use only the above-mentioned hydroxyl group-containing monomer as the monomer containing a functional group having reactivity.

On the other hand, examples of the monomer which does not contain a reactive functional group include (meth) acrylic acid alkoxyalkyl esters such as methoxy (meth) acrylate and ethoxyethyl (meth) acrylate, vinyl acetate and styrene . These may be used alone or in combination of two or more.

The polymerization of the (meth) acrylic acid ester polymer (A) may be a random copolymer or a block copolymer.

The weight average molecular weight of the (meth) acrylic acid ester polymer (A) is preferably 100,000 or more as the lower limit value, more preferably 200,000 or more, and further preferably 300,000 or more. If the lower limit of the weight-average molecular weight of the (meth) acrylic acid ester polymer (A) is higher than the above-mentioned range, the resulting pressure-sensitive adhesive has a higher film strength. The upper limit of the weight average molecular weight of the (meth) acrylic acid ester polymer (A) is preferably 90,000 or less, more preferably 800,000 or less, and further preferably 700,000 or less. When the upper limit of the weight average molecular weight of the (meth) acrylic acid ester polymer (A) is not more than the above value, the obtained pressure sensitive adhesive exhibits excellent step traceability. The weight average molecular weight in the present specification is a value in terms of standard polystyrene measured by Gel Permeation Chromatography (GPC).

In the sticky composition P, the (meth) acrylic acid ester polymer (A) may be used singly or in combination of two or more.

(2) The polyrotaxane compound (B)

The polyrotaxane compound (B) is a compound in which straight-chain molecules penetrate into the openings of at least two cyclic molecules and have block groups at both ends of the linear molecule. In this polyrotaxane compound (B), it is possible for the cyclic molecule to freely move in the linear molecular phase, but the structure is such that the cyclic molecule can not escape from the linear molecule by the block group. That is, the straight-chain molecule and the cyclic molecule are not chemical bonds such as covalent bonds, but maintain their shape by so-called mechanical bonding. When the pressure-sensitive adhesive composition P contains the polyrotaxane compound (B) having such a mechanical bond, the resulting pressure-sensitive adhesive is improved in 1000% modulus (or modulus at break) without lowering stress relaxation property. As a result, the pressure-sensitive adhesive layer has enhanced film strength and excellent workability.

The polyrotaxane compound (B) preferably has a cyclic oligosaccharide as a cyclic molecule. The use of a cyclic oligosaccharide as the cyclic molecule of the polyrotaxane compound (B) makes it possible to select an appropriate ring diameter, and thereby the effect of the cyclic molecule moving on the linear molecule is likely to be manifested. When the cyclic oligosaccharide has a hydroxyl group as a reactive group, the reaction with the isocyanate-based crosslinking agent (C) is easy. Further, introduction of various substituents and the like is facilitated, whereby the compatibility of the polyrotaxane compound (B) with the other components can be controlled by the polyrotaxane compound (B). In addition, there is an advantage that a cyclic oligosaccharide can be easily obtained. In the present specification, the "cyclic molecule" of "cyclic molecule" or "cyclic oligosaccharide" means substantially "cyclic". That is, if it is movable on a linear molecule, the cyclic molecule may not be completely ring closed, but may be, for example, a helical structure.

As the cyclic oligosaccharide, cyclodextrins such as? -Cyclodextrin,? -Cyclodextrin and? -Cyclodextrin can be preferably exemplified. Of these,? -Cyclodextrin is particularly preferable. The cyclic molecule of the polyrotaxane compound (B) may be mixed in the polyrotaxane compound (B) or in the adhesive composition P in combination.

When a cyclic molecule (cyclic oligosaccharide) of the polyrotaxane compound (B) has a hydroxyl group as a reactive group, the hydroxyl group may be a hydroxyl group having a cyclic oligosaccharide at the original (pre-modification) state, It also contributes to the fisheries.

The lower limit of the hydroxyl value of the cyclic molecule is preferably 10 mgKOH / g or more, more preferably 30 mgKOH / g or more, and particularly preferably 50 mgKOH / g or more. If the lower limit of the hydroxyl value is higher than the lower limit, the polyrotaxane compound (B) can sufficiently react with the isocyanate crosslinking agent (C). The upper limit of the hydroxyl value of the cyclic molecule is preferably 1000 mgKOH / g or less, more preferably 200 mgKOH / g or less, and particularly preferably 100 mgKOH / g or less. When the upper limit value of the hydroxyl value exceeds the above value, a large number of crosslinks are generated in the same cyclic molecule, so that the cyclic molecule itself becomes a crosslinking point and the crosslinking point effect as the whole polyrotaxane compound (B) can not be exhibited I think. As a result, it is conceivable that the stepwise followability by the addition of the polyrotaxane compound (B) will not have an effect of improving the film strength as it is.

The straight chain molecule of the polyrotaxane compound (B) is a molecule or a substance that is embedded in a cyclic molecule and can be integrated by mechanical bonding, not by chemical bonding such as covalent bonding, and is not limited as long as it is a straight chain. In the present specification, the term " linear chain " of " linear molecule " means substantially straight chain. That is, when the cyclic molecule is movable on the linear molecule, the linear molecule may have a branched chain.

Examples of the linear molecule of the polyrotaxane compound (B) include linear polyolefins such as polyethylene glycol, polypropylene glycol, polyisoprene, polyisobutylene, polybutadiene, polytetrahydrofuran, polyacrylic acid ester, polydimethylsiloxane, Propylene and the like are preferable, and these linear molecules may be mixed in two or more kinds among the adhesive composition P.

The number average molecular weight of the straight chain molecule of the polyrotaxane compound (B) is preferably 3,000 or more as the lower limit value, more preferably 10,000 or more, and further preferably 20,000 or more. If the lower limit of the number average molecular weight is above the above value, the amount of cyclic molecules on the linear molecule is secured, and the stress relaxation property of the pressure sensitive adhesive is sufficiently obtained. The upper limit of the number average molecular weight of the straight chain molecule of the polyrotaxane compound (B) is preferably 300,000 or less, more preferably 200,000 or less, further preferably 100,000 or less. If the upper limit of the number average molecular weight is not more than the above range, the solubility in the solvent of the polyrotaxane compound (B) and the compatibility with the (meth) acrylic acid ester polymer (A) become good.

The block group of the polyrotaxane compound (B) is not particularly limited as long as it is a group capable of maintaining the form in which the cyclic molecule is skewered by the linear molecule. Examples of such a group include a bulky group and an ionic group.

Specifically, the blocking group of the polyrotaxane compound (B) is preferably a block copolymer having a number average molecular weight of from 1,000 to 1,000,000, such as a dinitrophenyl group stream, a cyclodextrin group, an adamantane group stream, a trityl group stream, a fluorescein group, And the like. These block groups may be contained in the polyrotaxane compound (B) or in the adhesive composition P in combination of two or more.

The polyrotaxane compound (B) described above can be obtained by a conventionally known method (for example, a method described in Japanese Patent Application Laid-Open No. 2005-154675).

The content of the polyrotaxane compound (B) in the sticky composition P is preferably 3 parts by mass or more, particularly preferably 5 parts by mass or more, as a lower limit value with respect to 100 parts by mass of the (meth) acrylic acid ester polymer (A) More preferably 7 parts by mass or more. When the content of the polyrotaxane compound (B) is 3 parts by mass or more, 1000% modulus (or modulus at break) of the resultant pressure-sensitive adhesive increases, and the processability is further improved. In addition, when the content of the polyrotaxane compound (B) is 7 parts by mass or more, the stepwise followability of the obtained pressure sensitive adhesive is also improved. The upper limit of the content of the polyrotaxane compound (B) is preferably 30 parts by mass or less, more preferably 25 parts by mass or less, particularly preferably 20 parts by mass or less, and even more preferably 15 parts by mass or less. When the content of the polyrotaxane compound (B) is 30 parts by mass or less, the processability of the resultant pressure-sensitive adhesive is more excellent and the compatibility with the (meth) acrylic acid ester polymer (A) is maintained satisfactorily and the haze value of the obtained pressure- Can be suppressed to a low level. Further, when the content of the polyrotaxane compound (B) is 15 parts by mass or less, the stepwise followability of the resulting pressure sensitive adhesive is also improved.

(3) Isocyanate-based crosslinking agent (C)

The isocyanate crosslinking agent (C) is excellent in reactivity with the hydroxyl group of the hydroxyl group-containing monomer in the (meth) acrylic acid ester polymer (A) and the cyclic oligosaccharide in the cyclic molecule of the polyrotaxane compound (B) .

The isocyanate crosslinking agent (C) comprises at least a polyisocyanate compound. Examples of the polyisocyanate compound include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate and xylylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate Alicyclic polyisocyanates such as aliphatic polyisocyanates, and alicyclic polyisocyanates such as their buret resins, isocyanurate compounds, and furthermore, adducts with reaction products of low molecular active hydrogen such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylol propane, And the like. Among them, trimethylolpropane-modified aromatic polyisocyanates, especially trimethylolpropane-modified tolylene diisocyanate and trimethylolpropane-modified xylylene diisocyanate are preferable from the viewpoint of reactivity with hydroxyl groups. The isocyanate crosslinking agent (C) may be used alone or in combination of two or more.

The content of the isocyanate crosslinking agent (C) in the adhesive composition P is preferably 0.05 part by mass or more, particularly preferably 0.1 part by mass or more as a lower limit value with respect to 100 parts by mass of the (meth) acrylic acid ester polymer (A) Is preferably 0.2 parts by mass or more. If the lower limit of the content of the isocyanate crosslinking agent (C) is higher than the above-mentioned range, it is estimated that the above-mentioned higher-order structure can be formed satisfactorily, and the resulting pressure sensitive adhesive exhibits better step traceability under high temperature and high humidity. The content of the isocyanate crosslinking agent (C) is preferably not more than 3 parts by mass, particularly preferably not more than 2 parts by mass, and more preferably not more than 1 part by mass, per 100 parts by mass of the (meth) acrylic acid ester polymer (A) Or less. If the upper limit of the content of the isocyanate-based crosslinking agent (C) is not more than the above range, the degree of crosslinking can be set to be suitable, and the following step of the obtained pressure-sensitive adhesive can be satisfactorily ensured.

(4) Various additives

The pressure-sensitive adhesive composition P may contain various additives commonly used in acrylic pressure-sensitive adhesives, for example, silane coupling agents, reaction accelerators, reaction inhibitors, ultraviolet absorbers, antistatic agents, tackifiers, antioxidants, light stabilizers, A refractive index adjusting agent and the like may be added. It is also assumed that the polymerization solvent or diluting solvent to be described later is not included in the additive constituting the adhesive composition P.

The silane coupling agent is preferably an organosilicon compound having at least one alkoxysilyl group in the molecule, good compatibility with the (meth) acrylic acid ester polymer (A), and light transmittance.

Examples of such silane coupling agents include polymerizable unsaturated group-containing silicon compounds such as vinyltrimethoxysilane, vinyltriethoxysilane and methacryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, And silicon compounds having an epoxy structure such as 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3- (2-aminoethyl) -3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, -Aminopropylmethyldimethoxysilane, an amino group-containing silicon compound such as 3-chloropropyltrimethoxysilane, 3-isocyanatepropyltriethoxysilane, or a combination of at least one of these with methyltriethoxysilane, ethyltriethoxysilane , Methyltrimethoxy What may be a condensate of such an alkyl group-containing silicon compound, such as, ethyl trimethoxysilane. These may be used singly or in combination of two or more kinds.

When the sticky composition P contains a silane coupling agent, its content is preferably 0.01 part by mass or more, particularly preferably 0.05 part by mass or more as a lower limit value with respect to 100 parts by mass of the (meth) acrylic acid ester polymer (A) 0.1 part by mass or more. The upper limit of the content of the silane coupling agent is preferably 1 part by mass or less, more preferably 0.5 part by mass or less, further preferably 0.3 part by mass or less.

(5) Production of sticky composition

The adhesive composition P is obtained by preparing a (meth) acrylic acid ester polymer (A), mixing the obtained (meth) acrylic acid ester polymer (A), the polyrotaxane compound (B) and an isocyanate crosslinking agent , And adding an additive as desired.

The (meth) acrylic acid ester polymer (A) can be produced by polymerizing a mixture of monomers constituting the polymer by a conventional radical polymerization method. The polymerization of the (meth) acrylic acid ester polymer (A) is preferably carried out by a solution polymerization method using a polymerization initiator as desired. As the polymerization solvent, for example, ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, methyl ethyl ketone and the like may be used.

Examples of the polymerization initiator include an azo compound, an organic peroxide, and the like, and two or more types may be used in combination. Examples of the azo compound include 2,2'-azobisisobutyronitrile, 2,2'-azobis (2-methylbutyronitrile), 1,1'-azobis (cyclohexane 1-carbonitrile Azo compounds such as 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (2,4-dimethyl-4-methoxy valeronitrile) Azo compounds such as bis (2-methylpropionate), 4,4'-azobis (4-cyanovaleric acid), 2,2'-azobis (2-hydroxymethylpropionitrile) Bis [2- (2-imidazolin-2-yl) propane] and the like.

Examples of the organic peroxide include benzoyl peroxide, t-butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, di (2-ethoxyethyl) peroxydicarbonate, t-butyl peroxyneodecanoate, t-butyl peroxypivalate, (3,5,5-trimethylhexanoyl) peroxide, dipropionyl peroxide, and diacetyl peroxide.

In addition, the weight average molecular weight of the resulting polymer can be controlled by blending a chain transfer agent such as 2-mercaptoethanol in the polymerization step.

(B), an isocyanate-based crosslinking agent (C), and a diluting solvent and additives as required, are added to a solution of the (meth) acrylic acid ester polymer (A) And the mixture is sufficiently mixed to obtain a sticky composition P (coating solution) diluted with a solvent. In addition, in the case of using any of the above-mentioned components in a solid phase or in the case of causing precipitation when mixed with other components in a non-diluted state, the components are dissolved or diluted in a diluting solvent in advance , Or may be mixed with other components.

Examples of the diluting solvent include aliphatic hydrocarbons such as hexane, heptane and cyclohexane, aromatic hydrocarbons such as toluene and xylene, halogenated hydrocarbons such as methylene chloride and ethylene chloride, alcohols such as methanol, ethanol, propanol, Propanol and the like; ketones such as acetone, methyl ethyl ketone, 2-pentanone, isophorone and cyclohexanone; esters such as ethyl acetate and butyl acetate; cellosolve solvents such as ethyl cellosolve; Is used.

The concentration and viscosity of the coating solution thus prepared are not particularly limited and may be appropriately selected according to the circumstances. For example, it is diluted such that the concentration of the sticky composition P is 10 to 60 mass%. In addition, when obtaining the coating solution, it is not necessary to add a diluting solvent or the like, and a diluting solvent may not be added if the viscosity is such that the adhesive composition P can be coated. In this case, the adhesive composition P becomes a coating solution containing the polymerization solvent of the (meth) acrylic acid ester polymer (A) as it is as a diluting solvent.

(6) Production of pressure-sensitive adhesive

A pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet according to the present embodiment can be preferably obtained by crosslinking the pressure-sensitive adhesive composition P. The crosslinking of the adhesive composition P can be usually carried out by heat treatment. This heat treatment may also be used as a drying treatment for volatilizing a diluting solvent or the like from a coating film of the adhesive composition P applied to a desired object.

The heating temperature for the heat treatment is preferably 50 to 150 占 폚, particularly preferably 70 to 120 占 폚. The heating time is preferably 10 seconds to 10 minutes, particularly preferably 50 seconds to 2 minutes.

After the heat treatment, a curing period of about 1 to 2 weeks may be set at room temperature (for example, 23 DEG C, 50% RH), if necessary. If the curing period is necessary, after the curing period has elapsed, if the curing period is not necessary, the pressure-sensitive adhesive is formed after the heat treatment is finished.

The (meth) acrylic acid ester polymer (A) (and the polyrotaxane compound (B)) is sufficiently crosslinked by the heat treatment (and curing) through the isocyanate crosslinking agent (C). The pressure-sensitive adhesive obtained in this way is excellent in step-following property and exhibits high film strength.

(7) Gel fraction of the pressure-sensitive adhesive

The gel fraction of the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet according to the present embodiment, in particular, the pressure-sensitive adhesive composition obtained from the pressure-sensitive adhesive composition P is preferably 40% or more, more preferably 45% or more, particularly preferably 50% , And more preferably 60% or more. If the lower limit of the gel fraction of the pressure-sensitive adhesive is higher than the above-mentioned range, the cohesive force of the pressure-sensitive adhesive increases and the film strength of the pressure-sensitive adhesive layer becomes higher. The upper limit of the gel fraction of the pressure-sensitive adhesive obtained from the adhesive composition P is preferably 90% or lower, more preferably 85% or lower, further preferably 80% or lower. If the upper limit of the gel fraction of the pressure-sensitive adhesive is less than the above range, the pressure-sensitive adhesive is not excessively hard and the pressure-sensitive adhesive layer is more excellent in step-wise followability. Here, the measurement method of the gel fraction of the pressure-sensitive adhesive is as shown in the following test example.

(8) Thickness of the pressure-sensitive adhesive layer

The thickness of the pressure-sensitive adhesive layer (measured in accordance with JIS K7130) in the pressure-sensitive adhesive sheet according to the present embodiment is preferably 10 占 퐉 or more as the lower limit value, more preferably 25 占 퐉 or more, and particularly preferably 50 占 퐉 or more. If the lower limit of the thickness of the pressure-sensitive adhesive layer 11 is higher than the above-mentioned value, a desired adhesive force is easily exerted, and satisfactory step traceability to the ordinary step of the display member constituting member can be ensured. The upper limit of the thickness of the pressure-sensitive adhesive layer 11 is preferably 1000 占 퐉 or less, more preferably 400 占 퐉 or less, and particularly preferably 300 占 퐉 or less. If the upper limit of the thickness of the pressure-sensitive adhesive layer 11 is less than the above value, the workability becomes good. Further, the pressure-sensitive adhesive layer 11 may be formed as a single layer, or a plurality of layers may be laminated.

3. Specific composition of adhesive sheet

Fig. 1 shows a specific configuration as an example of the pressure-sensitive adhesive sheet according to the present embodiment.

1, the pressure-sensitive adhesive sheet 1 according to one embodiment is formed by two peeling sheets 12a and 12b and two peeling sheets 12a and 12b in contact with the peeling surfaces of the two peeling sheets 12a and 12b, And a pressure-sensitive adhesive layer 11 sandwiched between the sheets 12a and 12b. The release surface of the release sheet in the present specification means a surface having release properties in the release sheet and includes both the surface subjected to the release treatment and the surface exhibiting the release property without performing the release treatment.

(1) Pressure-sensitive adhesive layer

The pressure-sensitive adhesive layer (11) is composed of a pressure sensitive adhesive satisfying the above-mentioned physical properties, preferably a pressure sensitive adhesive obtained by crosslinking the pressure sensitive adhesive composition (P).

(2) Peeling sheet

The release sheets 12a and 12b protect the pressure-sensitive adhesive layer 11 by the use of the pressure-sensitive adhesive sheet 1 and are peeled off when the pressure-sensitive adhesive sheet 1 (pressure-sensitive adhesive layer 11) is used. In the pressure-sensitive adhesive sheet 1 according to the present embodiment, one or both of the release sheets 12a and 12b are not necessarily required.

As the release sheets 12a and 12b, for example, a polyethylene film, a polypropylene film, a polybutene film, a polybutadiene film, a polymethylpentene film, a polyvinyl chloride film, a vinyl chloride copolymer film, a polyethylene terephthalate film, (Meth) acrylic acid copolymer film, an ethylene / (meth) acrylic acid ester copolymer film, a polystyrene film, a polycarbonate film, a polyvinylidene fluoride film, a polyvinylidene fluoride film, Film, a polyimide film, a fluororesin film, or the like is used. These crosslinked films are also used. Further, these laminated films may be used.

It is preferable that a peeling treatment is performed on the peeling surface of the peeling sheets 12a and 12b (in particular, the surface in contact with the peeling layer 11). Examples of the releasing agent used in the peeling treatment include alkyd-based, silicone-based, fluorine-based, unsaturated polyester-based, polyolefin-based, and wax-based releasing agents. It is also preferable that one of the release sheets 12a and 12b is a heavy release type release sheet having a large release force and the other release sheet is a light release type release sheet having a small release force.

The thickness of the release sheets 12a, 12b is not particularly limited, but is usually about 20 to 150 mu m.

(3) Production of pressure-sensitive adhesive sheet

As one production example of the adhesive sheet 1, the application liquid of the adhesive composition P is applied to the release surface of one release sheet 12a (or 12b), heat-treated to thermally crosslink the adhesive composition P, After the layer is formed, the peeling surface of the other release sheet 12b (or 12a) is superimposed on the applied layer. When a curing period is required, a curing period is provided, and when the curing period is unnecessary, the applied layer becomes the pressure-sensitive adhesive layer (11). Thus, the pressure-sensitive adhesive sheet (1) is obtained. The conditions of the heat treatment and curing are as described above.

As another production example of the adhesive sheet 1, a coating liquid of the adhesive composition P is applied to the release surface of one release sheet 12a, heat treatment is performed to thermally crosslink the adhesive composition P, A release sheet 12a on which a coating layer is formed is obtained. The application liquid of the adhesive composition P is applied to the release surface of the other release sheet 12b and heat-treated to thermally crosslink the adhesive composition P to form a release layer. The release sheet 12b ). Then, the release sheet 12a on which the application layer is formed and the release sheet 12b on which the application layer is formed are bonded so that the both application layers come into contact with each other. When the curing period is required, the curing period is provided, and when the curing period is unnecessary, the laminated coating layer becomes the pressure-sensitive adhesive layer (11). Thus, the pressure-sensitive adhesive sheet (1) is obtained. According to this production example, even if the pressure-sensitive adhesive layer 11 is thick, it can be stably produced.

As a method for applying the coating liquid of the adhesive composition P, for example, a bar coating method, a knife coating method, a roll coating method, a blade coating method, a die coating method, a gravure coating method and the like can be used.

In the pressure-sensitive adhesive sheet 1 according to the present embodiment, since the adhesive strength of the pressure-sensitive adhesive layer 11 is high, when the pressure-sensitive adhesive sheet 1 is punched out, It is possible to suppress the occurrence of problems such as dropping out of the apparatus. In addition, when the adhesive sheet 1 is stored, the pressure-sensitive adhesive layer 11 is prevented from leaking out.

[Display]

As shown in Fig. 2, the display body 2 according to the present embodiment includes a first display body constituting member 21 (one display body constituting member) having a step on at least a surface to be conjugated, The pressure sensitive adhesive layer 11 which is located between the display body constituting member 22 (another display body constituting member) and the first display body constituting member 21 and the second display body constituting member 22 to be bonded to each other Respectively. In the display body 2 according to the present embodiment, the first display body constituting member 21 has a step on the surface of the pressure-sensitive adhesive layer 11 side, specifically, a stepped portion by the print layer 3 have.

The pressure sensitive adhesive layer 11 of the display body 2 is the pressure sensitive adhesive layer 11 of the pressure sensitive adhesive sheet 1 described above.

As the display body 2, for example, a liquid crystal (LCD) display, a light emitting diode (LED) display, an organic electroluminescence (organic EL) display, an electronic paper and the like may be mentioned. The display member 2 may be a member constituting a part of them.

The first display body constituting member 21 is preferably a protective panel made of a laminate or the like including a glass plate, a plastic plate and the like. In this case, the print layer 3 is generally formed as a frame on the side of the pressure-sensitive adhesive layer 11 of the first display body constituting member 21.

The glass plate is not particularly limited and examples thereof include chemical strengthened glass, alkali-free glass, quartz glass, soda lime glass, barium-strontium glass, aluminosilicate glass, lead glass, borosilicate glass, barium borosilicate glass, have. The thickness of the glass plate is not particularly limited, but is usually 0.1 to 5 mm, preferably 0.2 to 2 mm.

The plastic plate is not particularly limited, and examples thereof include an acrylic plate and a polycarbonate plate. The thickness of the plastic plate is not particularly limited, but is usually 0.2 to 5 mm, preferably 0.4 to 3 mm.

In addition, various functional layers (a transparent conductive film, a metal layer, a silica layer, a hard coat layer, an antiglare layer and the like) may be formed on one or both surfaces of the glass plate or the plastic plate, or optical members may be laminated. The transparent conductive film and the metal layer may be patterned.

The second display body constituting member 22 is constituted by an optical member to be affixed to the first display body constituting member 21, a display module (for example, a liquid crystal (LCD) module, a light emitting diode Luminescent (organic EL) module or the like), an optical member as a part of the display body module, or a display body module.

Examples of the optical member include a light-scattering film, a polarizing plate (polarizing film), a polarizer, a retardation film (phase difference film), a viewing angle compensation film, a brightness enhancement film, a contrast enhancement film, a liquid crystal polymer film, , And a transparent conductive film. Examples of the shake-prevention film include a hard coat film formed by forming a hard coat layer on one side of a base film.

The material constituting the print layer 3 is not particularly limited, and known materials for printing are used. The thickness of the printing layer 3, that is, the lower limit of the height of the stepped portion is preferably 3 mu m or more, more preferably 5 mu m or more, particularly preferably 7 mu m or more, most preferably 10 mu m or more. By setting the lower limit to the above value, it is possible to sufficiently secure concealment such as making the electric wiring from being invisible from the viewer side. The upper limit value is preferably 50 탆 or less, more preferably 35 탆 or less, particularly preferably 25 탆 or less, and more preferably 20 탆 or less. When the upper limit value is less than or equal to the upper limit value, it is possible to prevent degradation of the step traceability of the pressure-sensitive adhesive layer 11 with respect to the print layer 3.

In order to manufacture the display body 2, for example, one of the release sheets 12a of the pressure-sensitive adhesive sheet 1 is peeled off, and the exposed pressure-sensitive adhesive layer 11 of the pressure- To the side of the member (21) on which the print layer (3) is present. At this time, since the pressure-sensitive adhesive layer 11 is excellent in step-following ability, it is possible to suppress the occurrence of gap or lifting in the vicinity of the stepped portion by the printed layer 3.

Thereafter, the other release sheet 12b is peeled from the pressure-sensitive adhesive layer 11 of the pressure-sensitive adhesive sheet 1, and the exposed pressure-sensitive adhesive layer 11 and the second display member constituting member 22 of the pressure- It merges. As another example, the order of combining the first display body constituting member 21 and the second display body constituting member 22 may be changed.

In the display body 2 described above, since the pressure sensitive adhesive layer 11 has excellent step traceability even under high-temperature and high-humidity conditions, the display body 2 is kept under a high temperature and high humidity condition (for example, % RH), the occurrence of bubbles, lifting, peeling, and the like in the vicinity of the step is suppressed.

The embodiments described above are described for the purpose of facilitating understanding of the present invention and are not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design modifications and equivalents falling within the technical scope of the present invention.

For example, one or both of the release sheets 12a and 12b in the adhesive sheet 1 may be omitted, or a desired optical member may be laminated instead of the release sheets 12a and / or 12b. The first display body constituting member 21 may have a step difference other than the print layer 3. Further, not only the first display body constituting member 21 but also the second display body constituting member 22 may have a step on the pressure-sensitive adhesive layer 11 side.

[Example]

Hereinafter, the present invention will be described in more detail with reference to Examples and the like, but the scope of the present invention is not limited to these Examples and the like.

[Example 1]

1. Preparation of (meth) acrylic acid ester polymer

60 parts by mass of 2-ethylhexyl acrylate, 20 parts by mass of isobornyl acrylate, 5 parts by mass of 4-acryloylmorpholine and 15 parts by mass of 2-hydroxyethyl acrylate were copolymerized to obtain a (meth) acrylic acid ester polymer (A) It was prepared. The molecular weight of the (meth) acrylic acid ester polymer (A) was measured by the method described later, and the weight average molecular weight (Mw) was 60,000.

2. Preparation of adhesive composition

100 parts by mass of the (meth) acrylic acid ester polymer (A) obtained in the above Step 1 (solid content conversion value: the same in the following) and the polyrotaxane compound (B) (trade name: "SILM SUPER POLYMER SH3400P" manufactured by Advanced Soft Matrix Co., Cyclic dextrin having a hydroxyl group and caprolactone chain, block group: adamantane, weight average molecular weight (Mw) of 700,000, and hydroxyl value of 72 mgKOH / g), straight chain molecule: polyethylene glycol, cyclic molecule: , 0.25 parts by mass of trimethylolpropane-modified tolylene diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd., product name: Coronate L) as an isocyanate cross-linking agent (C), and 0.25 parts by mass of 3-glycidoxypropyltrimethoxy And 0.25 parts by mass of silane (product name: KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.) were mixed and sufficiently stirred and diluted with methyl ethyl ketone to obtain a sticking composition having a solid content concentration of 40% by mass To obtain a coating solution.

Table 1 shows the respective blend (solid content conversion value) of the adhesive composition when the (meth) acrylic acid ester polymer (A) was changed to 100 parts by mass (solid content conversion value). Details of the abbreviations and the like listed in Table 1 are as follows.

[(Meth) acrylic acid ester polymer (A)]

2EHA: 2-ethylhexyl acrylate

IBXA: isobornyl acrylate

ACMO: 4-acryloylmorpholine

HEA: 2-hydroxyethyl acrylate

BA: n-butyl acrylate

MMA: methyl methacrylate

CHA: cyclohexyl acrylate

MA: methyl acrylate

[Isocyanate crosslinking agent (C)]

TDI: trimethylolpropane-modified tolylene diisocyanate (product name "Coronate L", manufactured by Nippon Polyurethane Industry Co., Ltd.)

XDI: trimethylolpropane-modified xylylene diisocyanate (product name: " TD-75 ", manufactured by Soken Chemical &

3. Production of adhesive sheet

The coating solution of the sticky composition obtained in the above Step 2 was applied on a release treatment surface of a heavy-duty release sheet (product name "SP-PET752150", manufactured by Lin Tec Co., Ltd.) in which one side of the polyethylene terephthalate film was stripped with a silicone- Respectively. Then, the coated layer was heat-treated at 90 DEG C for 1 minute to form a coated layer.

Then, the coated layer on the heavy-weight releasing sheet obtained above and the light-receding type releasing sheet (product name: "SP-PET382120", manufactured by Lin Tec Co., Ltd.) in which one side of the polyethylene terephthalate film was peeled off with a silicone- Sensitive adhesive layer (thickness: 25 占 퐉) / light-weight receding peel sheet by curing for 7 days under conditions of 23 占 폚 and 50% RH. 1 pressure-sensitive adhesive sheet.

The coating solution of the adhesive composition obtained in the above step 2 was applied to the release treatment surface of a heavy-duty release sheet (product name: " SP-PET752150 ", manufactured by Lin Tec Co., Ltd.) in which one side of the polyethylene terephthalate film was stripped with a silicone- Coated with a coater, and then subjected to heat treatment at 90 占 폚 for 1 minute to form a coating layer (thickness: 25 占 퐉). Likewise, the coating solution of the sticky composition obtained in the above Step 2 was applied to a release treatment surface of a lightly receding type release sheet (product name: " SP-PET382120 ", manufactured by Lin Tec Co., Ltd.) in which one side of a polyethylene terephthalate film was peeled off with a silicone- Coated with a coater, and then subjected to heat treatment at 90 占 폚 for 1 minute to form a coating layer (thickness: 25 占 퐉).

Next, the heavy-duty releasing sheet on which the coating layer obtained above was formed and the lightly curled releasing sheet on which the coating layer obtained was formed were put in contact so that the both coating layers were in contact with each other, and cured for 7 days under conditions of 23 deg. Thereby forming a second adhesive sheet having a configuration of a heavy-duty releasing sheet / pressure-sensitive adhesive layer (thickness: 50 占 퐉) / light-duty releasing sheet.

Further, the thickness of the pressure-sensitive adhesive layer is a value measured using a static pressure thickness gauge (product name: "PG-02", manufactured by Tecklakk Co., Ltd.) in accordance with JIS K7130.

[Examples 2 to 15 and Comparative Examples 1 to 5]

(A), the type and ratio of each monomer constituting the (meth) acrylic acid ester polymer (A), the weight average molecular weight of the (meth) acrylic acid ester polymer (A), the blending amount of the polyrotaxane compound (B) A pressure-sensitive adhesive sheet was produced in the same manner as in Example 1, except that the kind and blending amount and the blending amount of the silane coupling agent were changed as shown in Table 1.

The weight average molecular weight (Mw) described above is a weight average molecular weight in terms of polystyrene measured by gel permeation chromatography (GPC) under the following conditions (GPC measurement).

<Measurement Conditions>

GPC measurement apparatus: HLC-8020 manufactured by Toso Co., Ltd.

· GPC column (pass in the following order): Toso Co., Ltd.

   TSK guard column HXL-H

   TSK gel GMHXL (× 2)

   TSK gel G2000HXL

Measurement solvent: tetrahydrofuran

· Measuring temperature: 40 ℃

[Test Example 1] (Measurement of gel fraction)

The first pressure-sensitive adhesive sheet (pressure-sensitive adhesive layer thickness: 25 占 퐉) obtained in Examples and Comparative Examples was cut into a size of 80 mm 占 80 mm, the pressure-sensitive adhesive layer was wrapped with a polyester mesh (mesh size 200) Was weighed with a precision balance, and the mass of the adhesive alone was calculated by subtracting the mass of the mesh alone. The mass at this time is defined as M1.

Next, the pressure-sensitive adhesive wrapped in the polyester mesh was immersed in ethyl acetate at room temperature (23 DEG C) for 24 hours. Thereafter, the pressure-sensitive adhesive was taken out and air-dried for 24 hours under an environment of a temperature of 23 ° C and a relative humidity of 50%, and further dried in an oven at 80 ° C for 12 hours. After drying, the mass was weighed with a precision balance, and the mass of the adhesive alone was calculated by subtracting the mass of the mesh alone. Let the mass at this time be M2. The gel fraction (%) is represented by (M2 / M1) x100. The results are shown in Table 2.

[Test Example 2] (Measurement of haze value)

(Manufactured by Nippon Denshoku Co., Ltd., product name: &quot; NDH-2000 &quot;) was used for the pressure-sensitive adhesive layer of the first pressure-sensitive adhesive sheet (pressure-sensitive adhesive layer thickness: 25 탆) obtained in Examples and Comparative Examples, according to JIS K7136: And the haze value (%) was measured. The results are shown in Table 2.

[Test Example 3] (Tensile test)

A plurality of pressure-sensitive adhesive layers of the second pressure-sensitive adhesive sheet (pressure-sensitive adhesive layer thickness: 50 占 퐉) obtained in the Examples and Comparative Examples were laminated to obtain a total thickness of 600 占 퐉 and then a sample of 10 mm width 占 75 mm length was cut out. The sample was set in a tensile tester (product name: "Tensilon" manufactured by Orientech Co., Ltd.) such that the sample measurement site was 10 mm wide × 20 mm length (elongation direction) At a tensile rate of 200 mm / min, and the stress value at which the elongation percentage was 1000% was measured as 1000% modulus (MPa). In addition, in the case where the specimen was broken before the elongation percentage reached 1000%, the stress value at the time of the fracture was measured (modulus at the time of fracture). The results are shown in Table 2 (the parentheses in Table 2 are the modulus at break).

In the tensile test, the sample was stretched until the sample was broken, and the elongation at break of the sample, that is, the elongation at break (%) was measured. The results are shown in Table 2.

[Test Example 4] (Measurement of adhesive force)

The lightly recoil peeling sheet was peeled from the first adhesive sheet (thickness of the pressure-sensitive adhesive layer: 25 mu m) obtained in Examples and Comparative Examples, and the exposed pressure-sensitive adhesive layer was laminated on a polyethylene terephthalate (PET) Manufactured by Toshiba Machine Co., Ltd., product name "PET A4300", thickness: 100 μm) to obtain a laminate of release sheet / pressure-sensitive adhesive layer / PET film. The obtained laminate was cut into a 25 mm width and a 100 mm length, and this was used as a sample.

The peelable release sheet was peeled off from the sample under the environment of 23 占 폚 and 50% RH, and the exposed pressure-sensitive adhesive layer was attached to soda lime glass (manufactured by Nippon Sheet Glass Co., Ltd.) MPa and 50 DEG C for 20 minutes. The adhesive strength (N / 25) was measured under the conditions of a peeling speed of 300 mm / min and a peeling angle of 180 degrees using a tensile tester (Tensilon manufactured by Orientec Co., Ltd.) Mm) was measured. Conditions other than those described herein were measured in accordance with JIS Z 0237: 2009. The results are shown in Table 2.

[Test Example 5] (Measurement of wet heat adhesion)

The sample obtained in the same manner as in Test Example 4 was peeled from the pressure-sensitive adhesive layer under the environment of 23 ° C and 50% RH, and the exposed pressure-sensitive adhesive layer was attached to soda lime glass (manufactured by Nippon Sheet Glass Co., Ltd.) , And pressurized at 0.5 MPa and 50 캜 for 20 minutes with an autoclave manufactured by Kurihara Seisakusho Co., Ltd. Thereafter, the film was allowed to stand under the conditions of 60 ° C and 90% RH for 24 hours, and then allowed to stand for 24 hours under the conditions of normal pressure, 23 ° C. and 50% RH. Thereafter, using a tensile tester (Tensilon manufactured by Orientec Co., Ltd.) (N / 25 mm) was measured under conditions of a speed of 300 mm / min and a peel angle of 180 degrees. Conditions other than those listed here were measured in accordance with JIS Z 0237: 2009. The results are shown in Table 2.

[Test Example 6] (Measurement of step following rate)

(Trade name: POS-911, manufactured by Teikoku Ink Co., Ltd.) was applied onto the surface of a glass plate (product name: "Corning Glass Eagle XG", length 90 mm × width 50 mm × thickness 0.5 mm, manufactured by NSG Precision) Screen printing was performed in a frame shape (outer shape: 90 mm in length × 50 mm in width and 5 mm in width) so that the coating thickness was any one of 5 μm, 10 μm, 15 μm, 20 μm and 25 μm. Subsequently, the printed ultraviolet curable ink was cured by irradiating ultraviolet rays (80 W / cm 2, a metal halide lamp 2 lamp, a lamp height of 15 cm, and a belt speed of 10 to 15 m / min) Height: 5 mu m, 10 mu m, 15 mu m, 20 mu m, and 25 mu m).

The lightly peelable release sheet was peeled off from the second pressure-sensitive adhesive sheet (pressure-sensitive adhesive layer thickness: 50 占 퐉) obtained in Examples and Comparative Examples, and the exposed pressure-sensitive adhesive layer was laminated on a polyethylene terephthalate film PET A4300 &quot;, thickness: 100 mu m). Subsequently, the heavy-duty release sheet was peeled off, and a pressure-sensitive adhesive layer was exposed. Then, the laminate was laminated on a glass plate having the respective steps so that the pressure-sensitive adhesive layer covers the entire printed surface on the frame, using a laminator (manufactured by Fuji Plastics Co., Ltd., product name "LPD3214").

The obtained evaluation sample was subjected to autoclave treatment at 50 캜 under 0.5 MPa for 30 minutes and then left at normal pressure, 23 캜, and 50% RH for 24 hours. Subsequently, the sample was stored for 72 hours under a high-temperature and high-humidity condition of 85 캜 and 85% RH (endurance test), and then the step traceability was evaluated. It is judged whether or not the printing step is completely embedded by the pressure-sensitive adhesive layer, and it is judged that the printing step can not be followed in the case where bubbles, lifting, peeling or the like are observed at the interface between the printing step and the pressure-sensitive adhesive layer . Here, the step following ability was evaluated as a step following rate (%) shown by the following equation. The results are shown in Table 2.

(%) = {(Height of stepped portion without bubbling, lifting, peeling, etc. after the endurance test and maintained in the embedded state) / (thickness of pressure-sensitive adhesive layer: 50 占 퐉)} x 100

[Test Example 7] (Evaluation of cut suitability)

A plurality of pressure-sensitive adhesive layers of the second pressure-sensitive adhesive sheet (pressure-sensitive adhesive layer thickness: 50 μm) obtained in Examples and Comparative Examples were laminated to obtain a laminate having a total thickness of 1 mm. The laminate was cut by a cutting device (product name: Super Cutter PN1-600, manufactured by Oginosei Co., Ltd.). The cut surface (length: 100 mm) of the pressure-sensitive adhesive layer after the cutting was visually confirmed, and the cut suitability was evaluated according to the following criteria. The results are shown in Table 2.

○: No peeling of the pressure-sensitive adhesive layer on the cut surface

△: Some adhesive layer was missing on the cut surface (less than 10% of the cut surface)

X: The pressure-sensitive adhesive layer is missing on the cut surface (10% or more of the cut surface)

As can be seen from Table 2, the pressure-sensitive adhesive sheet obtained in the Examples was excellent in step-following property and had good cutability, that is, high film strength.

The pressure-sensitive adhesive sheet of the present invention can be suitably used, for example, for bonding a protective panel having a step to a desired display body constituting member.

1: Pressure sensitive adhesive sheet
11: Pressure-sensitive adhesive layer
12a, 12b: peeling sheet
2:
21: first display body constituting member
22: second display body constituting member
3: Printing layer

Claims (5)

A pressure-sensitive adhesive sheet having one display body constructing member having a step on a side at least to be conjugated, and a pressure-sensitive adhesive layer for bonding other display body constructing members,
When the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is subjected to a tensile test at 23 占 폚, when the pressure-sensitive adhesive is broken before reaching 1000% modulus or elongation percentage of 1000% of the pressure-sensitive adhesive, the modulus at break is 0.22 MPa or more,
Wherein the stepwise follow-up rate of the pressure-sensitive adhesive layer is not less than 30%
Wherein the pressure-sensitive adhesive sheet is a pressure-sensitive adhesive sheet. The pressure-sensitive adhesive sheet according to claim 1, wherein the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer has a elongation at break of at least 500% when subjected to a tensile test at 23 ° C. The pressure-sensitive adhesive sheet according to claim 1, wherein the pressure-sensitive adhesive layer has a haze value of 5% or less. The pressure-sensitive adhesive sheet according to claim 1, wherein the pressure-sensitive adhesive sheet comprises two release sheets,
Wherein the pressure-sensitive adhesive layer is sandwiched between the peeling sheets so as to come into contact with the peeling surfaces of the two peeling sheets
Wherein the pressure-sensitive adhesive sheet is a pressure-sensitive adhesive sheet. A display element constituting member having a step on a surface of at least a side to be conjugated,
Another display body constituting member,
A pressure-sensitive adhesive layer for bonding the one display body constituting member and the other display body constituting member to each other
And a display body,
Wherein the pressure-sensitive adhesive layer is a pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet according to any one of claims 1 to 4
.

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