JP2014185253A - Double-sided adhesive sheet, double-sided sheet take-up body and laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of producing a double-sided adhesive sheet which is of a new non-carrier type and prevents de-wetting phenomena without use of a wet lamination method, an adhesive sheet, an adhesive sheet take-up body and a laminate.SOLUTION: A non-carrier double-sided adhesive sheet 31 has an adhesive layer (A) 32 and an end part material (B) 33 on a separator 34, and the adhesive composition forming the adhesive layer (A) 32 is higher in surface tension than the end part material (B) 33. The adhesive composition forming the adhesive layer (A) is an energy ray-curable adhesive composition containing a monomer and a polymerization initiator. Peel force between the adhesive layer (A) and the separator is 1 N/50 mm or smaller.

Description

  The present invention relates to a double-sided PSA sheet, a double-sided PSA sheet roll, and a laminate.

In recent years, display devices such as a liquid crystal display (LCD) and input devices used in combination with the display device such as a touch panel have been widely used in various fields. In the production of these display devices and input devices, a transparent double-sided pressure-sensitive adhesive sheet is used for the purpose of bonding optical members. Moreover, the transparent double-sided adhesive sheet is used also for bonding with a display apparatus and an input device.
As the double-sided pressure-sensitive adhesive sheet used for such applications, a non-carrier type without a base material has become common.

Such a non-carrier double-sided tape is manufactured by (1) applying a solvent-free adhesive coating to the first separator, bonding the second separator and then curing, (2) solvent Two methods are generally used: a method in which a pressure-sensitive adhesive diluted with (1) is applied onto a first separator, dried and cured, and then bonded to a second separator.
Among these, in the former production method, in particular, an active energy ray-curable adhesive coating is applied onto the first separator, and the second separator is bonded in a substantially liquid state (wet laminating method). ) Is often cured by active energy rays. This technique is disclosed in US Pat. No. 4,181,752 (Patent Document 1).

  By the way, the fundamental factor that the non-carrier type double-sided pressure-sensitive adhesive sheet (pressure-sensitive adhesive layer) can be peeled from the separator is that the surface tension of the double-sided pressure-sensitive adhesive sheet is higher than the surface tension of the separator (support). In other words, when the surface tension of the double-sided pressure-sensitive adhesive sheet is lower than that of the support, the double-sided pressure-sensitive adhesive tape has a sufficient adhesive force with the support, so that it is very difficult to peel the double-sided pressure-sensitive adhesive sheet from the support.

  Therefore, in the case of a solventless adhesive coating, in order to obtain a non-carrier type double-sided adhesive tape (adhesive layer), the adhesive coating must be higher than the separator surface tension. However, when this is applied to the first separator, a dewetting phenomenon such as a thick end (also referred to as framing or fat edge) occurs, resulting in a manufacturing problem.

One method for preventing the dewetting phenomenon is a wet laminating method. This is because the wet laminating method regulates the thickness of the pressure-sensitive adhesive and suppresses the flow of liquid. However, in the wet laminating method, the thickness of the pressure-sensitive adhesive changes due to a change in the tension of the web accompanying the conveyance of the web or a circumferential difference in the web conveyance roll, and as a result, the thickness of the pressure-sensitive adhesive layer tends to vary. Remains.

In the case of solvent-diluted adhesive coatings, the surface tension of the coating material is lower than the surface tension of the separator because it is diluted with a solvent with a low surface tension, and dewetting phenomena such as thick edges do not occur. . In the subsequent drying step, the surface tension of the coating agent increases with the volatilization of the solvent, but the viscosity also increases and the coating agent is immobilized, so that the dewetting phenomenon does not occur.

U.S. Pat. No. 4,181,752

  The present invention has been made in view of the above circumstances, and in a pressure-sensitive adhesive sheet in which a pressure-sensitive adhesive layer is formed with a solventless pressure-sensitive adhesive composition, a new non-carrier type that prevents the dewetting phenomenon without depending on the wet laminating method It aims at providing a double-sided adhesive sheet, a double-sided adhesive sheet winding body, and a laminated body.

The present invention for solving the above problems has the following aspects.
[1] A double-sided pressure-sensitive adhesive sheet in which a pressure-sensitive adhesive layer (A) and an end material (B) are formed on a separator, wherein the surface tension of the pressure-sensitive adhesive composition formed by the pressure-sensitive adhesive layer (A) is A non-carrier double-sided pressure-sensitive adhesive sheet characterized by being higher than the surface tension of the material (B).
[2] The non-carrier double-sided pressure-sensitive adhesive sheet according to [1], wherein the pressure-sensitive adhesive composition forming the pressure-sensitive adhesive layer (A) is an active energy ray-curable pressure-sensitive adhesive composition containing a monomer and a polymerization initiator.
[3] The non-carrier double-sided pressure-sensitive adhesive sheet according to [1] or [2], wherein a peeling force between the separator and the pressure-sensitive adhesive layer (A) is 1 N / 50 mm or less.
[4] The non-carrier double-sided pressure-sensitive adhesive sheet according to any one of [1] to [3], wherein a length in a width direction of the end material (B) is 5 to 10 mm.
[5] A non-carrier double-sided pressure-sensitive adhesive sheet for bonding members from which the end material (B) has been removed from the non-carrier double-sided pressure-sensitive adhesive sheet according to any one of [1] to [4].
[6] A non-carrier double-sided pressure-sensitive adhesive sheet winding body in which the non-carrier double-sided pressure-sensitive adhesive sheet according to any one of [1] to [4] is wound around a core material.
[7] A laminate obtained by bonding a pair of optical members via the non-carrier double-sided pressure-sensitive adhesive sheet according to any one of [1] to [5].

  According to the present invention, a non-carrier double-sided PSA sheet, a wound body or a laminate having an adhesive layer (A) can be obtained without causing a dewetting phenomenon without depending on a wet lamination method.

It is a figure which shows the adhesive sheet winding body which is embodiment of this invention. It is a figure which shows the cross section of the adhesive sheet which is embodiment of this invention.

The non-carrier double-sided pressure-sensitive adhesive sheet 31 of the present invention is a double-sided pressure-sensitive adhesive sheet in which a pressure-sensitive adhesive layer (A) 32 and an end material (B) 33 are formed on a separator 34, and the pressure-sensitive adhesive formed by the pressure-sensitive adhesive layer (A). The surface tension of the composition is higher than the surface tension of the end material (B). The description of the constituent elements described below is made based on typical embodiments and specific examples of the present invention, but the present invention is not limited to such embodiments and specific examples.

[Adhesive composition]
The pressure-sensitive adhesive composition forming the pressure-sensitive adhesive layer (A) has a surface tension higher than that of the end material (B). The pressure-sensitive adhesive composition having a high surface tension includes a solvent-less pressure-sensitive adhesive diluted with a solvent to such an extent that the surface tension does not become too low.
Hereinafter, the solventless pressure-sensitive adhesive will be described in detail.

[Solvent-free adhesive]
As the solvent-free technology for the pressure-sensitive adhesive, there are an emulsion type, a hot-melt type, and the like, but the present invention relates to a pressure-sensitive adhesive in which the coating material flows at room temperature.
Among them, the active energy ray-curable pressure-sensitive adhesive is a syrup pressure-sensitive adhesive obtained by thickening a pressure-sensitive adhesive material mainly composed of a monomer to a viscosity suitable for coating. Examples of the syrup manufacturing method include a method of dissolving the thickening polymer resin in the monomer and a method of partially polymerizing the monomer by bulk polymerization.
As a method of producing syrup by bulk polymerization, a method of polymerizing by supplying a monomer and a pyrolytic initiator, a method using a barrel type reactor equipped with a UV irradiation window of a UV transparent material, a reaction of an optical fiber A method of introducing UV into the layer and continuously or intermittently irradiating with UV has been proposed.

[Syrup by bulk polymerization and method for producing the same]
As a method for producing syrup by bulk polymerization, for example, the following method disclosed in Japanese Patent Application Laid-Open No. 2001-181589 can be given.

In the production of the syrup pressure-sensitive adhesive, a monomer having a polymerizable unsaturated bond is used as a monomer. The monomer having a polymerizable unsaturated bond is mainly composed of an acrylic acid alkyl ester, and examples of the monomer having such a polymerizable unsaturated bond include the following compounds.
Acrylic such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, pentyl acrylate, hexyl acrylate, -2-ethylhexyl acrylate, octyl acrylate, nonyl acrylate, decyl acrylate, dodecyl acrylate Acid alkyl esters; acrylic acid aryl esters such as phenyl acrylate and benzyl acrylate; alkoxyalkyl acrylates such as methoxyethyl acrylate, ethoxyethyl acrylate, propoxyethyl acrylate, butoxyethyl acrylate, ethoxypropyl acrylate Salts such as acrylic acid and alkali metal acrylates; salts such as methacrylic acid and alkali metal methacrylates; methyl methacrylate, ethyl methacrylate, propyl methacrylate, Methacrylic acid alkyl esters such as butyl crylate, pentyl methacrylate, hexyl methacrylate, -2-ethylhexyl methacrylate, octyl methacrylate, nonyl methacrylate, decyl methacrylate, dodecyl methacrylate; phenyl methacrylate, benzyl methacrylate Methacrylic acid aryl esters such as: methoxyethyl methacrylate, ethoxyethyl methacrylate, propoxyethyl methacrylate, butoxyethyl methacrylate, alkoxyalkyl methacrylates such as ethoxypropyl methacrylate; ethylene glycol diacrylate, diethylene glycol diacryl Acid esters, triethylene glycol diacrylate, polyethylene glycol diacrylate, propylene glycol (Poly) alkylene glycol diacrylates such as Cole diacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate; ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, tri Dimethacrylic of (poly) alkylene glycols such as ethylene glycol dimethacrylate, polyethylene glycol diacrylate, propylene glycol dimethacrylate, dipropylene glycol dimethacrylate, tripropylene glycol dimethacrylate Acid esters; polyacrylic esters such as trimethylolpropane triacrylate; trimethylolpro Polyvalent methacrylates such as pantrimethacrylates; acrylonitrile; methacrylonitrile; vinyl acetate; vinylidene chloride; vinyl halide compounds such as 2-chloroethyl acrylate and 2-chloroethyl methacrylate; cyclohexyl acrylate Acrylic esters of alicyclic alcohols such as: Methacrylic esters of alicyclic alcohols such as cyclohexyl methacrylate; 2-vinyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-iso Oxazoline group-containing polymerizable compounds such as propenyl-2-oxazoline; Aziridine group-containing polymerizable compounds such as acryloylaziridine, methacryloylaziridine, acrylate-2-aziridinylethyl acrylate, and 2-aziridinylethyl methacrylate; Allyl glycidyl ether, acrylic Epoxy group-containing vinyl monomers such as glycidyl ether, glycidyl methacrylate, glycidyl acrylate, acrylate-2-ethyl glycidyl ether, and methacrylic acid-2-ethyl glycidyl ether; -2-hydroxyethyl acrylate, methacryl Such as 2-hydroxyethyl acid, 2-hydroxypropyl acrylate, monoesters of acrylic acid or methacrylic acid and polypropylene glycol or polyethylene glycol, and adducts of lactones with 2-hydroxyethyl (meth) acrylate Hydroxyl group-containing vinyl compounds; fluorine-containing vinyl monomers such as fluorine-substituted methacrylic acid alkyl esters and fluorine-substituted acrylic acid alkyl esters; excluding (meth) acrylic acid, such as itaconic acid, crotonic acid, maleic acid, and fumaric acid Unsaturated carboxylic acids, their salts and their (partial) ester compounds and acid anhydrides; reactive halogen-containing vinyl monomers such as 2-chloroethyl vinyl ether and vinyl monochloroacetate; methacrylamide, N-methylol methacrylamide Amide group-containing vinyl monomers such as N-methoxyethyl methacrylamide and N-butoxymethyl methacrylamide; vinyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, allyltrimethoxysilane, trimethoxysilylpropylallylamine, Organosilicon group-containing vinyl compound monomers such as 2-methoxyethoxytrimethoxysilane; other macromonomers having a radical polymerizable vinyl group at the end of the monomer polymerized with vinyl groups (eg, fluorine-based monomers, silicon-containing monomers) Monomer It can be exemplified macromonomer, styrene, silicon, etc.).

These polymerizable unsaturated compounds can be used alone or in combination. However, the composition of the polymerizable unsaturated compound is such that the glass transition temperature according to the Fox formula is usually 0 ° C. or lower, preferably The composition is in the range of −85 to 0 ° C. In addition, there is no restriction | limiting in particular in content of the alkyl acrylate ester in the monomer which has a polymerizable unsaturated bond used in this bulk polymerization method.

In the bulk polymerization for producing the syrup used in the present invention, the monomer having the unsaturated bond is reacted substantially without using a reaction solvent. In this bulk polymerization, the monomer having an unsaturated bond is preferably polymerized using a specific polymerization initiator as shown below. As the polymerization initiator used here, a polymerization initiator having a 10-hour half-life temperature of 41.0 ° C. or lower, preferably in the range of 20 to 37.0 ° C., as exemplified below, is preferably used. Is done.

Examples of such polymerization initiators include isobutyryl peroxide (10-hour half-life temperature: 32.7 ° C.), α, α′-bis (neodecanoylperoxy) diisopropylbenzene (10-hour half-life temperature: 35.9 ° C), cumylperoxyneodecanoate (10-hour half-life temperature: 36.5 ° C), di-n-propyl peroxydicarbonate (10-hour half-life temperature: 40.3 ° C), diisopropyl par Oxydicarbonate (10-hour half-life temperature: 40.5 ° C), di-sec-butyl peroxydicarbonate (10-hour half-life temperature: 40.5 ° C), 1, 1, 3, 3, -tetramethylbutyl Peroxyneodecanoate (10-hour half-life temperature: 40.7 ° C), bis (4-butylcyclohexyl) peroxydicarbonate (10-hour half-life temperature: 40.8 ° C) and 2,2'-azobis ( 4-Methoxy-2,4-dimethylvaleronitrile ) (10-hour half-life temperature: 30.0 ° C.) can be mentioned.

These polymerization initiators can be used alone or in combination. Among these, isobutyryl peroxide (10-hour half-life temperature: 32.7 ° C), α, α'-bis (neodecanoylperoxy) diisopropylbenzene (10-hour half-life temperature: 35.9 ° C), kumi Luperoxyneodecanoate (10-hour half-life temperature: 36.5 ° C), 2,2'-azobis (4-methoxy-2,4-dimethylvaleronitrile) (10-hour half-life temperature: 30.0 ° C) It is preferable to use 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile) (10 hour half-life temperature: 30.0 ° C.).

The polymerization initiator is a thermal polymerization initiator, and its 10-hour half-life temperature is extremely low. For example, the conventionally used polymerization initiator tert-butyl peroxyisoptylate has a 10-hour half-life temperature of 72.1 ° C, and benzoyl peroxide has a 10-hour half-life temperature of 74 ° C. The 10 hour half-life temperature of 2,2'-azobisisobutyronitrile is 66 ° C. When such a thermal polymerization initiator having a high 10-hour half-life temperature is used, in the bulk polymerization reaction, the reaction proceeds rapidly immediately after the start of the reaction, and the control of the reaction becomes very difficult.

In the production of the syrup used in the present invention, instead of using a thermal polymerization initiator having a high 10-hour half-life temperature as described above, a small amount of a thermal polymerization initiator having a remarkably low 10-hour half-life temperature is used for polymerization. Allow the reaction to proceed. That is, in the present invention, such a polymerization initiator having a low 10-hour half-life temperature is within a range of 0.0001 to 0.5 parts by weight, preferably 100 parts by weight of the monomer having a polymerizable unsaturated bond, It is used in an amount in the range of 0.0005 to 0.1 parts by weight, more preferably in the range of 0.001 to 0.05 parts by weight. The amount of such a polymerization initiator used is very small compared to the amount used of a reaction initiator in a normal bulk polymerization or the like, and the amount of monomers reacted with this polymerization initiator is small. Accordingly, although the polymerization heat generation amount is relatively small, usually, after the reaction system is first heated to start the reaction, the operation of applying heat to the reaction system from the outside is not performed. When the reaction is started, the reaction system generates heat due to consumption of the polymerization initiator, but in the present invention, since the amount of the polymerization initiator used is small, the heat generation amount is small and the reaction runs out of control. The temperature does not rise rapidly, and the polymerization initiator with a low 10-hour half-life temperature is used, so the polymerization initiator is consumed in a very short time, and the temperature of the reactant rapidly rises to initiate polymerization. Once all of the agent has been consumed, the temperature of the reactants will no longer increase. When the amount of the polymerization initiator greatly deviates from the above lower limit, the polymerization initiator is consumed by the polymerization inhibitor that is normally blended so that the reaction of the monomer as a raw material does not proceed during storage, etc. The polymerization reaction does not proceed.

After the reaction starts, the maximum temperature of the reaction product is within the range of 100 to 140 ° C., preferably within the range of 100 to 130 ° C. by utilizing the self-heating of the reaction system due to consumption of the polymerization initiator. The upper limit of this temperature range should not be exceeded. Usually, after heating to start the polymerization reaction, the heating or heating operation is stopped, and the temperature of the reaction system is in the range of 100 to 140 ° C., preferably utilizing the self-heating accompanying the progress of the polymerization reaction, preferably It reaches within the range of 100 ° C. or more and less than 130 ° C.

When the temperature of the reaction system exceeds 140 ° C., the runaway reaction due to thermal polymerization starts, and it becomes difficult to control this thermal runaway reaction. Also, if the maximum temperature is less than 100 ° C., the bulk polymerization reaction cannot proceed to a preferred polymerization rate, the initiator remains in the reaction system, and the polymerization proceeds during storage of the reaction product. There are problems such as. When the scale of the reaction increases, especially in the production at the factory level where the reaction raw material exceeds 1000 kg, if the reaction system temperature is close to, for example, 150 ° C., the reaction runaway may occur if a normal cooling device is used. It is difficult to stop the runaway reaction unless a method such as adding a large amount of polymerization inhibitor is used, and it is difficult to stop the runaway reaction if the reaction temperature exceeds 180 ° C. That is, when a polymerization initiator having a high 10-hour half-life temperature as used conventionally is used, the initiator is not completely consumed at a temperature of 100 to 140 ° C., and the temperature of the reaction system rises. As the temperature rises, the thermal polymerization newly proceeds, and the temperature of the reaction system further rises. Finally, it becomes impossible to control the reaction. It is a runaway reaction in bulk polymerization.

In the syrup used in the present invention, the temperature of the reaction system is set to 100 by mainly utilizing the reaction heat generated by the polymerization reaction caused by using a small amount of a polymerization initiator having a low 10-hour half-life temperature of 41.0 ° C. or less. The temperature is rapidly increased within the range of ˜140 ° C., the polymerization initiator is consumed in a short time, and the maximum reaction temperature is suppressed to 140 ° C. or lower where the reaction can be controlled.

And it is preferable that the time which keeps the maximum temperature of such reaction in the range of 100-140 degreeC is short, and it is preferable to maintain the maximum temperature of reaction in the said range for 30 second-2 minutes. If the maximum temperature reached within the above temperature range is much shorter than the above lower limit and short, the polymerization reaction may not proceed effectively, and if it is long above the upper limit and long, an undesirable thermal polymer may be generated. There is.

Thus, a partial polymerization product in which 5 to 50% by weight of the monomer used as a raw material is polymerized can be obtained by a single polymerization reaction using the selected polymerization initiator. Then, if necessary, a new polymerization initiator is added and this process is repeated, so that at each stage, 5 to 50% by weight of the combined amount of the polymer and the monomer having a polymerizable unsaturated bond reacts. By repeating the operation, the polymer weight% of the partially polymerized product can be increased. Moreover, since the reaction in each step proceeds under mild conditions, there is no occurrence of a large number of short-chain polymers as in the case of a runaway bulk polymerization product, and a uniform polymer with a uniform molecular weight is not generated. Can be manufactured.

In such a method, the monomer is heated or heated to a temperature at which the polymerization reaction can proceed when a polymerization initiator is added, and the polymerization reaction proceeds by adding the prescribed amount of the predetermined initiator to the monomer. Let The temperature of the monomer when the polymerization initiator is added is usually 20 to 80 ° C., preferably 35 to 70 ° C., particularly preferably 40 to 65 ° C. The polymerization initiator is usually added to the monomer thus heated or heated with stirring.

Although the said example is an example which heats a monomer and adds a polymerization initiator, mixing and heating of this monomer and a polymerization initiator can be performed in arbitrary orders. For example, after mixing the monomer and the polymerization initiator, it can be heated to a temperature at which the reaction starts, or after adding the polymerization initiator after heating the monomer to the temperature at which the reaction starts, as described above. It can also be mixed.

The heating temperature of the monomer necessary for effectively initiating the polymerization reaction as described above is usually 20-80.
° C, preferably 35 to 70 ° C, particularly preferably 40 to 65 ° C. By heating to such a temperature, the polymerization initiator begins to act effectively and the polymerization reaction begins to proceed effectively. Once the polymerization reaction is started in this manner, the polymerization initiator is chain-decomposed and the reaction proceeds and the temperature of the reaction system is within the range of 100 to 140 ° C. It is not necessary to heat or warm, and as long as the polymerization initiator as described above is used as described above, the maximum temperature does not exceed 140 ° C., and thus cooling is not particularly required. However, the present invention does not exclude a temperature adjustment operation such as a heating operation, a heating operation, or a cooling operation for adjusting the temperature of the reaction system at such a stage.

Thus, the polymerization reaction starts, and when the reaction starts in this way, the temperature of the reaction system rises rapidly due to self-heating. When the maximum temperature reaches 100 to 140 ° C., the added polymerization initiator is almost completely consumed, so the amount of heat generated as the reaction proceeds decreases, and the amount of heat released from the reaction system increases. . Therefore, the temperature of the reaction system does not increase any more, and if left as it is, the temperature of the reaction system becomes lower than 100 ° C. In the present invention, the reactant that has reached the maximum temperature can be left to cool, but in the present invention, it is preferable to lower the temperature of the reaction system to less than 100 ° C. in as short a time as possible. Once the temperature reaches the maximum temperature, it is possible to use a cooling device provided in the reactor, or add unheated monomer to the reaction system (monomer thinning). The temperature can be lowered to 100 ° C. in a short time, or the temperature of the reaction system can be lowered to 100 ° C. or less by a known cooling operation or means such as a combination thereof. For the monomer thinning, it is preferable to use a monomer contained in the reaction system. In this case, the amount of the monomer used is usually 10 to 50 weights with respect to 100 parts by weight of the initially charged monomer. Parts, preferably 20-30 parts by weight.

By making it react in this way, the partial polymerization syrup which 15 to 50 weight% of the preparation monomer superposed | polymerized is obtained. The partially polymerized syrup obtained in this manner is usually obtained as a viscous liquid (measured using a B-type viscometer at 0.1 to 50 Pa · S). In particular, in order to apply on a support, it is preferable to use a partial polymer in which the viscosity of the partial polymer measured in the same manner is in the range of 1 to 50 Pa · S.

After cooling the syrup obtained as described above to a temperature of less than 100 ° C., a small amount of the above-mentioned polymerization initiator having a 10-hour half-life temperature of 41.0 ° C. or less is added and mixed, and heated again to polymerize. The operation of resuming can be performed. By repeating this operation, the polymerization rate of the partially polymerized syrup gradually increases. In the present invention, a monomer having a polymerizable unsaturated bond and a specific polymerization initiator are used in a specific amount as described above, but normal dodecyl mercaptan, butyl mercaptan, 3-mercaptopropionic acid, thioglycolic acid, A chain transfer agent such as thioglycolate may be used in combination. Such a chain transfer agent is usually used in an amount in the range of 0.001 to 10 parts by weight, preferably 0.01 to 0.5 parts by weight, with respect to 100 parts by weight of the monomer used.

The polymerization reaction is preferably performed with stirring, and the reaction is preferably performed in an inert atmosphere such as nitrogen gas. Furthermore, since oxygen dissolved in the raw material used may hinder the progress of the reaction, it is preferable to use it after removing dissolved oxygen in the raw material used. The acrylic pressure-sensitive adhesive tape of the present invention is obtained by applying a pressure-sensitive adhesive containing the partial polymer obtained as described above, a cross-linking agent, and a photopolymerization initiator on a support, followed by photopolymerization. The pressure-sensitive adhesive layer is formed on at least one surface of the support.

Here, as the crosslinking agent, an epoxy crosslinking agent or an isocyanate crosslinking agent is used alone or in combination. Examples of the epoxy crosslinking agent to be used include 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, N, N, N ′, N′-tetraglycyl-m-xylylenediamine and the like. . Examples of the isocyanate crosslinking agent include trimethylhexanemethylenediamine and isophorone diisocyanate.

As a photopolymerization initiator, 4- (2-hydroxyethoxy) phenyl (2-hydroxy-2-propyl)
Ketone, α-hydroxy-α, α'-dimethylacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2-hydroxy-2-cyclohexylacetophenone, benzyldimethyl ketal, halogenated ketone, acylphosphine oxide, acylphosphonate And so on. Such photopolymerization initiators can be used alone or in combination.

The crosslinking agent is usually used in an amount of 0.001 to 10 parts by weight with respect to 100 parts by weight of the partial polymer. The photopolymerization initiator is usually used in an amount of 0.0001 to 10 parts by weight, preferably 0.001 to 6 parts by weight, based on 100 parts by weight of the monomer. The pressure-sensitive adhesive composed of such components can be produced by blending the above components and stirring uniformly.

[Other optional ingredients]
The pressure-sensitive adhesive coating may optionally contain other components other than those described above as long as the effects of the present invention are not impaired. Examples of the other components include components known as additives for pressure-sensitive adhesives such as plasticizers, antioxidants, metal corrosion inhibitors, tackifiers, silane coupling agents, ultraviolet absorbers, hindered amine compounds, and the like. A stabilizer, a filler, an ionic liquid, and the like can be selected as necessary.
Examples of the plasticizer include non-functional acrylic polymers.
Examples of the antioxidant include phenolic antioxidants, amine-based antioxidants, lactone-based antioxidants, phosphorus-based antioxidants, sulfur-based antioxidants, and the like. These antioxidants may be used alone or in combination of two or more.
As the metal corrosion inhibitor, a benzoriazol-based resin is preferable because of the compatibility and high effect of the pressure-sensitive adhesive.
Examples of the tackifier include rosin resin, terpene resin, terpene phenol resin, coumarone indene resin, styrene resin, xylene resin, phenol resin, and petroleum resin.
Examples of the silane coupling agent include mercaptoalkoxysilane compounds (for example, mercapto group-substituted alkoxy oligomers).
Examples of the ultraviolet absorber include benzotriazole compounds and benzophenone compounds.
Examples of the ionic liquid include ionic liquids such as nitrogen-containing onium salts, sulfur-containing onium salts, and phosphorus-containing onium salts.

[Non-carrier double-sided adhesive sheet]
The non-carrier double-sided pressure-sensitive adhesive sheet 31 of the present invention includes a pressure-sensitive adhesive layer (A) 32 and an end material (B) 33 on a separator 34.
Here, the non-carrier double-sided pressure-sensitive adhesive sheet refers to a double-sided pressure-sensitive adhesive sheet that does not have a substrate or the like inside the pressure-sensitive adhesive layer.

〔separator〕
The separator 34 is a sheet having releasability on at least one side. The film used as the separator 34 is a peelable laminated film having a release film substrate and a release agent layer provided on one side of the release film substrate, or a polyethylene film, a polypropylene film, or the like as a low-polarity substrate. The polyolefin film is mentioned.
Papers and polymer films are used as the release film substrate in the peelable laminate film. As the release agent constituting the release agent layer, for example, a general-purpose addition type or condensation type silicone release agent or a long-chain alkyl group-containing compound is used.
Specific examples of silicone release agents include BY24-4527 and SD-7220 manufactured by Toray Dow Corning Silicone, KS-3600, KS-774, and X62-2600 manufactured by Shin-Etsu Chemical Co., Ltd. Is mentioned. Moreover, it is preferable to contain the silicone resin which is an organosilicon compound which has a SiO2 unit and a (CH3) 3SiO1 / 2 unit or CH2 = CH (CH3) SiO1 / 2 unit in a silicone type release agent. Specific examples of the silicone resin include BY24-843, SD-7292, SHR-1404, etc. manufactured by Toray Dow Corning Silicone, KS-3800, X92-183, manufactured by Shin-Etsu Chemical Co., Ltd., and the like.

  Although the thickness of the adhesion layer (A) 32 can be suitably set according to a use etc. and is not specifically limited, Usually, it exists in the range of 10-500 micrometers, and 20-350 micrometers is especially preferable. A non-carrier double-sided pressure-sensitive adhesive sheet can be easily produced when the thickness of the pressure-sensitive adhesive layer (A) 32 is not more than the upper limit.

  You may laminate | stack a 2nd separator on the surface on the opposite side to the surface which contact | connects the separator 34 of the adhesion layer (A) 32. In this case, in order to make it easy to peel, it is preferable that the separator 34 and the second separator laminated on the surface opposite to the surface in contact with the base material of the adhesive layer (A) 32 have different peelability. That is, if the peelability from one and the peelability from the other are different, it is easy to peel only the separator having the higher peelability first. In that case, what is necessary is just to adjust the peelability of one separator and the other separator according to the bonding method and the bonding order.

[End material (B)]
An end material (B) 33 is formed on the end 32 in the width direction of the non-carrier double-sided pressure-sensitive adhesive sheet.
The surface tension of the end material (B) 33 is larger than the surface tension of the separator 34 and larger than the surface tension of the pressure-sensitive adhesive composition forming the pressure-sensitive adhesive layer (A) 32.

  The length W in the width direction of the end material (B) 33 is preferably 5 mm or more, and more preferably 5 to 10 mm. When the width W is less than 5 mm, the end material (B) 33 is excessively narrow, and therefore, it is difficult to prevent dewetting. Moreover, when it exceeds 10 mm, there exists a possibility that the manufacturing cost of the double-sided adhesive sheet 31 may increase.

  The thickness T of the end material (B) 33 is preferably thinner than the adhesive layer (A) 32. Specifically, 0.95 times or less of the pressure-sensitive adhesive layer (A) is preferable, and 0.5 times or less is more preferable. If the thickness T of the end material (B) 33 exceeds the above range, there is a high risk of causing uneven thickness of the adhesive layer.

[Arrangement Method of End Material (B)]
The end material (B) 33 is formed on at least one width direction end of the non-carrier double-sided pressure-sensitive adhesive sheet 31 of the present invention. There are the following methods for forming the end material (B) 33 on the non-carrier double-sided pressure-sensitive adhesive sheet 31.
1. Separately prepared tape is sandwiched (arranged): The separately prepared end material (B) 33 is placed on at least one widthwise end of the double-sided pressure-sensitive adhesive sheet 31 when the non-carrier double-sided pressure-sensitive adhesive sheet 31 is manufactured. This is a method of obtaining the body 11.
2. Removal of release layer of separator: This is a method in which the release agent layer having release properties formed on the separator is removed using a good solvent of a release agent such as toluene to increase the surface tension.
3. Knurling: Knurling with a width of 5 mm was applied to the end of the separator in the width direction using a stamping roll as the end material (B). Also by this method, it is possible to remove a part of the release agent layer having releasability and increase the surface tension.

The non-carrier double-sided pressure-sensitive adhesive sheet 31 is formed, for example, by applying a pressure-sensitive adhesive composition that forms the pressure-sensitive adhesive layer (A) 32 on the separator 34 to form a coating film, and the polymerization reaction proceeds by irradiation with active energy rays. Thus, a cured product (adhesive layer (A) 32) is formed.
The adhesive coating can be applied using a known coating apparatus. Examples of the coating apparatus include a blade coater, an air knife coater, a roll coater, a bar coater, a gravure coater, a micro gravure coater, a rod blade coater, a lip coater, a die coater, and a curtain coater.

[Non-carrier double-sided PSA sheet for material bonding]
Although the non-carrier double-sided pressure-sensitive adhesive sheet 31 itself of the present invention can also be used for member bonding, the end portion of the non-carrier double-sided pressure-sensitive adhesive sheet 31 or the non-carrier double-sided pressure-sensitive adhesive sheet winding body 11 of the present invention by punching or slitting is used. By removing the material (B) 33, a non-carrier double-sided PSA sheet for bonding members can be obtained.
The non-carrier double-sided pressure-sensitive adhesive sheet for member bonding of the present invention is used for bonding with a member as will be described later.

[Non-carrier double-sided adhesive sheet roll]
As shown in FIG. 1, the pressure-sensitive adhesive sheet winding body 11 according to an embodiment of the present invention includes a core material 21 and a non-carrier double-sided sheet 31 wound around the core material surface 22. The core material 21 is formed in a horizontal cylindrical shape by a fiber reinforced plastic (FRP), an ABS plastic core, or the like, and the outer circumference in the cross section is less than 1 m. The non-carrier double-sided pressure-sensitive adhesive sheet 31 is formed of a synthetic resin material such as polyester, polypropylene, and nylon, and is used as a base film such as a coating film and a printing film in addition to being used for optical applications such as a liquid crystal display and a liquid crystal color television. Examples of the polyester include polyethylene terephthalate and polyethylene naphthalate. The non-carrier double-sided sheet 31 has a length in the length direction (longitudinal direction) of 50 to 15000 m, a length in the width direction (short direction) of 50 to 2000 mm, and a thickness of 30 to 500 μm.

[Laminate]
Using the non-carrier double-sided PSA sheet 31 of the present invention or the non-carrier double-sided PSA sheet for bonding members, two optical members can be bonded to produce a laminate. An optical member is each component in optical products, such as a touch panel and an image display apparatus. As a constituent member of the touch panel, for example, an ITO film in which an ITO film is provided on a transparent resin film, an ITO glass in which an ITO film is provided on the surface of a glass plate, a transparent conductive film in which a transparent polymer film is coated with a conductive polymer, Examples thereof include a hard coat film and an anti-fingerprint film. Examples of the constituent member of the image display device include an antireflection film, an alignment film, a polarizing film, a retardation film, and a brightness enhancement film used for a liquid crystal display device.
Examples of materials used for these members include glass, polycarbonate, polyethylene terephthalate, polymethyl methacrylate, polyethylene naphthalate, cycloolefin polymer, triacetyl cellulose, polyimide, and cellulose acylate.

  Examples of bonding a pair of optical members with a non-carrier double-sided pressure-sensitive adhesive sheet include bonding between ITO films inside the touch panel, bonding between the ITO film and ITO glass, bonding between the ITO film on the touch panel and the liquid crystal panel. Bonding of a cover glass and an ITO film, bonding of a cover glass and a decorative film, and the like can be mentioned.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated more concretely, this invention is not limited to these Examples.

[Example 1]
(Active energy ray-curable adhesive coating)
As an active energy ray-curable adhesive coating for forming the adhesive layer (A), a UV polymerization type solventless acrylic adhesive “SK Dyne Syrup” manufactured by Soken Chemical Co., Ltd. was used. This contains a photopolymerization initiator and the like.
(Separator with end material (B) formed)
A separator on which the end material (B) was formed was produced as follows. The mold release agent was removed from the width direction end of the polyethylene terephthalate film, which was manufactured by Toyobo Co., Ltd., only 5 mm wide using toluene to improve the surface tension of the width direction end. The part from which the release agent was removed was used as the end material (B).
(Production of double-sided PSA sheet)
The active energy ray-curable coating agent is applied onto the separator on which the end material (B) is formed, using a doctor blade YD type manufactured by Yoshimitsu Seiki Co., Ltd., so that the thickness after curing is 150 μm. It applied so that a coating liquid might be applied to edge part material (B). After leaving still for 3 minutes after coating, the adhesive layer (A) was obtained by irradiating an integrated light quantity of 5000 mJ / cm ² with an ultraviolet irradiator (ECS-301G1 manufactured by Eye Graphic Co., Ltd.).
A second separator (manufactured by Teijin DuPont Films Ltd.) was bonded to the adhesive layer (A) and the end material (B) to obtain a non-carrier double-sided adhesive sheet.

[Example 2]
Example 1 was performed except that the separator on which the end material (B) was formed was as follows.
(Separator with end material (B) formed)
A separator on which the end material (B) was formed was produced as follows. A polyethylene terephthalate film having a width of 5 mm that is not subjected to release treatment is pasted as an end material (B) on the end in the width direction of the release-treated polyethylene terephthalate film manufactured by Toyobo Co., Ltd. ) Was formed.

Example 3
The separator in which the end material (B) was formed was the same as in Example 1 except for the following.
(Separator with end material (B) formed)
A separator on which the end material (B) was formed was produced as follows. The end part in the width direction of the polyethylene terephthalate film subjected to release treatment manufactured by Toyobo Co., Ltd. was subjected to a knurling process having a width of 5 mm using a stamping roll as an end part material (B). By this knurling, the polyethylene terephthalate of the base material was exposed.

[Comparative Example 1]
A double-sided PSA sheet was obtained in the same manner as in Example 1 except that the end material (B) was not particularly disposed. Therefore, the separator corresponds to the end material (B).

〔Evaluation method〕
(Surface tension of adhesive coating)
The surface tension of the pressure-sensitive adhesive coating material forming the pressure-sensitive adhesive layer (A) was measured using a surface tension meter (CBVP-A3, manufactured by Kyowa Interface Science Co., Ltd.).
(Surface tension of separator and end material (B))
The surface tension of the separator and end material (B) was measured with a contact angle meter (manufactured by Kyowa Interface Chemical Co., Ltd., DM-501) as shown in Table 1 (liquids with known surface tension components: water and methylene iodide). Based on the Kaelble-Uy theory of Equation 1, the contact angle was calculated.

ここで、γ_Sは固体の表面張力、γ_Lはプローブ液体の表面張力、θは固体表面におけるプローブ液体の接触角である。この二元連立一次方程式を解けば表面張力が求められる。

Here, γ _S is the surface tension of the solid, γ _L is the surface tension of the probe liquid, and θ is the contact angle of the probe liquid on the solid surface. The surface tension can be obtained by solving this binary simultaneous linear equation.

(Evaluation of dewetting)
The width of the adhesive coating immediately after application was measured with a steel rule.
After 3 minutes from the application, UV irradiation was performed, and the width of the adhesive layer at that time was measured with a steel rule.
The obtained value was used as an index of dewetting by the following calculation formula.
100 × (width after UV irradiation) / (width immediately after application)
Pass (go): 95 or more and 100 or less, Fail (fail): Less than 95

(Evaluation of peel force)
The peeling force measured the peeling force of the adhesion layer (A) with respect to a to-be-coated separator based on the measurement of 180 degree peeling adhesive strength of JISZ0237: 2000. The width of the test piece was 50 mm, and the peeling speed was 300 mm / min.

While dewetting occurred in Comparative Example 1, no dewetting occurred in any of Examples 1 to 3.

DESCRIPTION OF SYMBOLS 11 ... Adhesive sheet winding body 21 ... Core material 22 ... Core material surface 31 ... Adhesive sheet 32 ... Adhesive layer (A)
33 ... End material (B)
34 ... Separator L ... Length T in the length direction of the pressure-sensitive adhesive sheet ... End material (B) thickness W ...... End material (B) width

The double-sided pressure-sensitive adhesive sheet, double-sided pressure-sensitive adhesive sheet roll and laminate of the present invention are useful for bonding optical members, for example, for producing a touch panel module, because dewetting phenomenon is unlikely to occur.

Claims (7)

A double-sided pressure-sensitive adhesive sheet in which a pressure-sensitive adhesive layer (A) and an end material (B) are formed on a separator, wherein the surface tension of the pressure-sensitive adhesive composition formed by the pressure-sensitive adhesive layer (A) is the end material (B A non-carrier double-sided pressure-sensitive adhesive sheet characterized by having a surface tension higher than   The non-carrier double-sided pressure-sensitive adhesive sheet according to claim 1, wherein the pressure-sensitive adhesive composition forming the pressure-sensitive adhesive layer (A) is an active energy ray-curable pressure-sensitive adhesive composition containing a monomer and a polymerization initiator. The non-carrier double-sided pressure-sensitive adhesive sheet according to claim 1 or 2, wherein a peeling force between the separator and the pressure-sensitive adhesive layer (A) is 1 N / 50 mm or less. The non-carrier double-sided pressure-sensitive adhesive sheet according to any one of claims 1 to 3, wherein a length in the width direction of the end material (B) is 5 to 10 mm. The non-carrier double-sided adhesive sheet for member bonding which removed the edge part material (B) from the non-carrier double-sided adhesive sheet in any one of Claims 1-4. The noncarrier double-sided adhesive sheet winding body which wound the noncarrier double-sided adhesive sheet in any one of Claims 1-4 to the core material. The laminated body formed by bonding a pair of optical member through the non-carrier double-sided adhesive sheet in any one of Claims 1-5.

Images