JP2008291071A - Pressure-sensitive adhesive composition and stacked body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pressure-sensitive adhesive composition which has excellent cohesion and suppresses peeling and light leakage attributed to the generation of residual stress when used for a heat shrinkable optical film, particularly for a polarizing plate stacked body. <P>SOLUTION: The pressure-sensitive adhesive composition contains a block resin which is obtained by polymerizing ethylenically unsaturated monomers including an ethylenically unsaturated monomer (A) having a hydroxyl group, and has a hydroxyl value of 0.3-30 mgKOH/g and a structure represented by [X]-[Y]-[Z], wherein the blocks [X] and [Z] of the block resin are blocks each independently having a glass transition temperature (Tg) of ≥10°C, the block [Y] is a block having a glass transition temperature (Tg) of ≤-10°C, and weight percentages of the blocks [X], [Y] and [Z] are 3-30 wt.%, 50-94 wt.% and 3-40 wt%, respectively. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a pressure-sensitive adhesive composition and a laminate comprising the pressure-sensitive adhesive composition. More specifically, the present invention relates to a pressure-sensitive adhesive composition suitable for use in laminating optical materials. The present invention also relates to a laminate in which an optical member is laminated on an adhesive layer formed from an adhesive composition, and provides a liquid crystal display device that can be used in a liquid crystal display device and has excellent visibility. It relates to a laminate that can be made.

  It is known that a solvent-type acrylic pressure-sensitive adhesive exhibits a holding power and a cohesive force by radical polymerization of a monomer having a functional group by general thermal radical polymerization and then curing with a curing agent. However, the laminate in which the optical member that is thermally shrunk by the pressure-sensitive adhesive is inferior in the suitability for use in an optical film because the stress remaining in the optical member remains. In particular, when this optical member was a polarizing plate, light leakage (heat unevenness) occurred due to residual stress.

On the other hand, studies have been reported in which a curing agent is blended in a resin having a functional group near the end designed by living radical polymerization and used as an adhesive composition. By performing such a design, a highly reactive functional group near the resin end can be used effectively, and high curability and cohesion can be obtained with a small amount of curing agent. However, even when such a resin is used with the above-mentioned pressure-sensitive adhesive composition for optical members, satisfactory physical properties have not been obtained. (Patent Documents 1 and 2)
Japanese Patent Laid-Open No. 11-236428 JP 2002-523570 A

  The present invention is a pressure-sensitive adhesive that has excellent cohesive force when used in a heat-shrinkable optical film, particularly a polarizing plate laminate, and also suppresses the occurrence of peeling and light leakage due to the occurrence of residual stress. An object is to provide a composition.

In the present invention, a hydroxyl value obtained by polymerizing an ethylenically unsaturated monomer containing an ethylenically unsaturated monomer (A) having a hydroxyl group is 0.3 to 30 mgKOH / g, and [X]-[Y]-[Z A block resin having a structure represented by:
A pressure-sensitive adhesive composition comprising a compound (B) having at least two functional groups capable of reacting with a hydroxyl group,
Blocks [X] and [Z] of the block resin are blocks each having a glass transition temperature (Tg) of 10 ° C. or higher independently, and block [Y] is a block having a glass transition temperature (Tg) of −10 ° C. or lower. And
The weight ratio of the blocks [X], [Y] and [Z] is [X] 3 to 40% by weight, [Y] 50 to 94% by weight, [Z] 3 to 40% by weight, and
The present invention relates to a pressure-sensitive adhesive composition characterized in that 80 to 100% by weight of the ethylenically unsaturated monomer (A) having a hydroxyl group is contained in blocks [X] and [Z].

  Furthermore, this invention relates to the said adhesive composition whose glass transition temperature (Tg) of block resin is -55-0 degreeC.

  Furthermore, this invention relates to the said adhesive composition whose weight average molecular weight (Mw) of block resin is 3000-300000.

  Furthermore, this invention relates to the said adhesive composition whose polydispersity [weight average molecular weight (Mw) / number average molecular weight (Mn)] of block resin is 1.1-2.5.

  Furthermore, the present invention relates to the pressure-sensitive adhesive composition obtained by polymerizing a block resin by an atom transfer radical polymerization method.

  Furthermore, the present invention provides the pressure-sensitive adhesive, wherein the functional group capable of reacting with a hydroxyl group in the compound (B) having at least two functional groups capable of reacting with a hydroxyl group is 1 to 50 mol% based on the hydroxyl group in the block resin. Relates to the composition.

  Furthermore, this invention relates to the laminated body by which an optical member is laminated | stacked on the adhesive layer formed from the said adhesive composition.

  Furthermore, this invention relates to the member for liquid crystal cells in which the glass member for liquid crystal cells, the adhesive layer formed from the said adhesive composition, and an optical member are laminated | stacked sequentially.

  According to the present invention, it was possible to provide a pressure-sensitive adhesive composition that has excellent cohesive force and suppresses the occurrence of peeling and light leakage due to the occurrence of residual stress.

  First, the block resin having a structure represented by [X]-[Y]-[Z] contained in the pressure-sensitive adhesive composition of the present invention will be described. The block resin of the present invention has a hydroxyl value of 0.3 to 30 mgKOH / g obtained by polymerizing an ethylenically unsaturated monomer containing an ethylenically unsaturated monomer (A) having a hydroxyl group. Furthermore, the blocks [X] and [Z] of the block resin are blocks having a glass transition temperature (Tg) of 10 ° C. or higher, and the block [Y] is a block having a glass transition temperature (Tg) of −10 ° C. or lower. Yes, the weight ratio of the blocks [X], [Y] and [Z] is [X] 3 to 40% by weight, [Y] 50 to 94% by weight, [Z] 3 to 40% by weight, 80 to 100% of the ethylenically unsaturated monomer (A) having the above is contained in the blocks [X] and [Z].

  The block resin of the present invention can be produced by a known method, but is preferably synthesized by sequential addition of monomers by living polymerization, particularly atom transfer radical polymerization. In this case, in consideration of deactivation of the active terminal of the polymerization, the monomer forming the block [X] is polymerized (first step), and after the polymerization yield exceeds 85% to 99%, the polymerization system is blocked. Polymerization is performed by adding a monomer that forms [Y] (second step). After the polymerization yield exceeds 85% to 99%, a monomer that forms block [Z] is added to the polymerization system. It is preferable to perform polymerization (third step). The obtained resin may be a block resin having a gradient structure, and therefore the block resin of the present invention includes a gradient structure.

  The block resin synthesized by such a method is composed of blocks [X] and [Z] having hydroxyl groups in the resin and a block [Y] having little or a small amount of hydroxyl groups in the properties of living polymerization. . The blocks [X] and [Z] having a hydroxyl group develop a cohesive force by a crosslinking reaction with a curing agent, and the block [Y] having no hydroxyl group or a small amount has an adhesive force or mechanical strength of the pressure-sensitive adhesive composition. It contributes to the characteristics.

  Further, the blocks [X] and [Z] may be constituted only by the ethylenically unsaturated monomer (A) having a hydroxyl group, but when only the ethylenically unsaturated monomer (A) having a hydroxyl group is polymerized, a resin In some cases, the resin may precipitate due to insufficient solubility in a general polymerization solvent, an ethylenically unsaturated monomer (A) having a hydroxyl group, and an ethylenically unsaturated monomer having no hydroxyl group that maintains the solubility of the resin; Is then copolymerized to form an ethylenically unsaturated monomer having no hydroxyl group and, if necessary, an ethylenically unsaturated monomer having a small amount of hydroxyl group (A) to polymerize the block. The block [Z] is synthesized by adding [Y] and adding an ethylenically unsaturated monomer (A) having a hydroxyl group and an ethylenically unsaturated monomer having no hydroxyl group. It is preferred.

  Examples of the ethylenically unsaturated monomer (A) having a hydroxyl group include, but are not limited to, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, glycerol mono (Meth) acrylic monomers having a hydroxyl group such as (meth) acrylate, 4-hydroxyvinylbenzene, 2-hydroxy-3-phenoxypropyl acrylate, polyalkylene glycol (meth) acrylates such as diethylene glycol mono (meth) acrylate, and the like. Can be mentioned. In addition, aromatic vinyl monomers having a hydroxyl group such as styrene derivatives such as hydroxystyrene, hydroxymethylstyrene, and hydroxyethylstyrene can be used. Furthermore, caprolactone adducts of these monomers are also included. These monomers may be used alone or in combination of two or more.

Known ethylenically unsaturated monomers having no hydroxyl group can be used, such as ethylene, buta-1,3-diene, 2-methylbuta-1,3-diene, 2-chlorobuta-1,3-diene. Dienes such as;
Styrenes such as styrene and α-methylstyrene;
Methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, normal butyl (meth) acrylate, tertiary butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, ethylhexyl (meth) acrylate , Cyclohexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, undecyl (meth) acrylate, lauryl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl (Meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acryl Over DOO, nonadecyl (meth) acrylate, eicosyl (meth) acrylate, heneicosyl (meth) acrylate, docosyl (meth) acrylate, alkyl (meth) acrylates having 1 to 22 carbon atoms such as isobornyl (meth) acrylate;
Benzyl (meth) acrylate, paracumylphenol EO modified (meth) acrylate, glycidyl (meth) acrylate, alkoxy polyethylene glycol (meth) acrylate, phenoxy polyethylene glycol (meth) acrylate, acrylamide, (meth) acrylamide, acrylonitrile, methacrylonitrile (Meth) acrylic acid derivatives such as;
Vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate and vinyl butyrate;
Vinyl ethers such as vinyl methyl ether and vinyl ethyl ether;
N-vinyl compounds such as vinyl methyl ketone, vinyl hexyl ketone, vinyl ketones, N-vinyl pyrrole, N-vinyl carbazole, N-vinyl indole, N-vinyl pyrrolidone;
Allyl compounds such as allyl chloride, allyl acetate, vinyl chloride, vinylidene chloride;
Examples thereof include (meth) acrylic acid esters having a fluorine alkyl group such as vinyl fluoride and vinylidene fluoride. These may be used alone or in combination of two or more.

  Although the monomer used for the block [Y] can be appropriately selected depending on the adhesiveness and heat resistance of the resin, it is preferable to use an alkyl (meth) acrylate monomer from the viewpoint of polymerization reactivity.

  In the present invention, the Tg of the blocks [X] and [Z] is 10 ° C. or higher, and the Tg of the block [Y] is 0 ° C. or lower. When the Tg of the blocks [X] and [Z] is less than 10 ° C., the cohesive force of the pressure-sensitive adhesive decreases. Although the upper limit of Tg of blocks [X] and [Z] depends on the high Tg known monomer used, it is preferably up to about 120 ° C. Moreover, when Tg of block [Y] exceeds 0 degreeC, the adhesive force of an adhesive will fall. Although the lower limit of Tg of block [Y] depends on the low Tg known monomer to be used, it is generally preferably up to −80 ° C. The Tg of each block referred to in the present invention was a value calculated by the following Fox equation.

1 / Tg = W1 / Tg1 + W2 / Tg2 +... + Wn / Tgn
W1 to Wn indicate the weight fraction of the monomer used, and Tg1 to Tgn indicate the glass transition temperature (unit: absolute temperature “K”) of each homopolymer.

The Tg of the main homopolymer used for the calculation is exemplified below.
2-ethylhexyl acrylate: -55 ° C (218K)
Normal butyl acrylate: -45 ° C (228K)
Lauryl methacrylate: -65 ° C (208K)
Isodecyl methacrylate: -41 ° C (232K)
Ethylhexyl methacrylate: -10 ° C (263K)
Acrylonitrile: 96 ° C (369K)
Methyl methacrylate: 105 ° C (378K)
Methyl acrylate: 10 ° C (283K)
Styrene: 100 ° C (373K)
Acrylamide: 153 ° C (426K)
Hydroxyethyl methacrylate: 55 ° C (328K)
2-hydroxypropyl methacrylate: 26 ° C (299K)

  In the atom transfer radical polymerization used in the present invention, in order to suppress side reactions that occur during general radical polymerization, depending on the charging ratio of the initiator of the atom transfer radical polymerization added during polymerization and the radical polymerizable monomer, The molecular weight of the resin and the ratio of the blocks [X], [Y], and [Z] can be freely controlled. In the block resin contained in the pressure-sensitive adhesive composition of the present invention, the weight ratio of the blocks [X], [Y] and [Z] is [X] 3 to 40% by weight, [Y] 50 to 94% by weight, [Z] 3 to 40% by weight. When the weight ratio of the blocks [X] and [Z] is less than 3% by weight, the cohesive force is insufficient, the adhesive remains on the adherend, and the heat resistance is significantly reduced. Mechanical properties cannot be obtained. On the other hand, if the weight ratio of the block [Y] is less than 50% by weight, the adhesive strength is insufficient.

  In the present invention, it is preferable to use 6 to 60% by weight of a monomer having a Tg of a homopolymer of 20 ° C. or higher based on the entire block resin. If the monomer having a Tg of 20 ° C. or higher in the homopolymer is less than 6% by weight, durability and cohesion may be insufficient, and if it exceeds 60% by weight, the adhesive strength may be lowered.

  The block resin of the present invention is characterized in that 80 to 100% by weight of the ethylenically unsaturated monomer (A) having a hydroxyl group is contained in the blocks [X] and [Z]. When the ethylenically unsaturated monomer (A) contained in the blocks [X] and [Z] is less than 80% by weight, the ratio of the hydroxyl group introduced near the resin terminal having high reactivity decreases, The reaction does not proceed and not only the cohesive force of the pressure-sensitive adhesive is obtained, but also the mechanical properties of the pressure-sensitive adhesive are lowered, and physical properties such as heat resistance, heat-and-moisture resistance and heat unevenness in optical applications are deteriorated.

  The hydroxyl value of the block resin used in the present invention is 0.3 to 30 mgKOH / g. More preferably, it is 1-20 mgKOH / g, Most preferably, it is 5-15 mgKOH / g. If the hydroxyl value of the resin is less than 0.3 mg KOH / g, the reaction site with the curing agent will be insufficient and the cohesive strength and durability will be impaired. If it exceeds 30 mg KOH / g, the mechanical properties as an adhesive will be impaired. Also, the optical characteristics and durability are deteriorated.

  The Tg of the block resin used in the present invention is preferably −55 to 0 ° C. More preferably, it is −40 to −20 ° C. If the Tg of the resin is less than -55 ° C, the heat resistance of the adhesive may be impaired, and if it exceeds 0 ° C, the adhesive strength may be insufficient.

  As a weight average molecular weight (Mw) of the block resin in this invention, 3000-300000 are preferable and 10,000-100,000 are especially preferable. If the Mw is less than 3000, the cohesive strength of the resin may be insufficient when used as an adhesive, and a large amount of curing agent may be required, and sufficient resistance cannot be obtained when used as a cured coating film. There is. If Mw exceeds 300,000, synthesis may take a long time.

  The polydispersity of the molecular weight of the block resin in the present invention [weight average molecular weight (Mw) / number average molecular weight (Mn)] is preferably 1.1 to 2.5, and particularly preferably 1.3 to 2.3. If the polydispersity of the molecular weight exceeds 2.5, a polymer having a low molecular weight is substantially increased, and further, a block resin having a structure represented by [X]-[Y]-[Z] is mixed. The adhesive properties may be adversely affected.

  The block resin in the present invention may newly introduce a functional group using a hydroxyl group contained in the resin. For example, a part of the hydroxyl group can be converted to a carboxyl group by reacting with an acid anhydride group in a polycarboxylic acid anhydride. By this reaction, a carboxyl group can be introduced into the block resin.

  Moreover, a part of the hydroxyl group contained in the resin is converted into an alkoxysilyl group by reacting with an alkoxysilyl group and a functional group capable of reacting with a hydroxyl group in a compound having a functional group capable of reacting with the hydroxyl group. . By this reaction, an alkoxysilyl group can be introduced into the block resin.

  The substituent converted from the hydroxyl group by the above method can be cured using a known catalyst or curing agent.

  Moreover, it can superpose | polymerize using the initiator which has a reactive functional group, or can introduce | transduce a functional group into the polymerization termination terminal of a polymer by a well-known method, and can utilize for reaction with a hardening | curing agent.

  Living polymerization is preferably used for the synthesis of the block resin of the present invention, and living radical polymerization is preferably used from the viewpoint of ease of synthesis and direct polymerization of a monomer having a polar group. It is particularly preferable to use an atom transfer radical polymerization method in view of speed. For atom transfer radical polymerization, known methods can be used for synthesis and catalyst removal.

  When water is mixed into the resin solution during the catalyst treatment process, the reaction between the block resin of the present invention and the curing agent may be inhibited. Therefore, a solvent miscible with water is added to the resin solution for azeotropic dehydration. It is desirable to remove moisture from the resin solution by such a process.

  The solution viscosity of the obtained block resin is not particularly limited and is selected depending on the use of the resin, but is preferably 100 to 50000 mP · s (25 ° C.). When used as an adhesive composition, 500 to 50000 mP · s (25 ° C.). When the viscosity exceeds 50000 mP · s (25 ° C.), coating is difficult, and when the viscosity is lower than 100 mP · s (25 ° C.), the resin flows during coating, which may make coating difficult.

  The pressure-sensitive adhesive composition of the present invention comprises the block resin and a compound (B) having at least two functional groups capable of reacting with a hydroxyl group as a curing agent. Furthermore, if necessary, a curing catalyst can be blended to form an adhesive composition. At this time, a solvent may be appropriately added in order to adjust the viscosity at the time of coating.

  In the pressure-sensitive adhesive composition, the compounding amount of the compound (B) is such that the functional group capable of reacting with the hydroxyl group in the compound (B) is 1 to 50 mol% with respect to the hydroxyl group in the block resin. Is preferable, and it is more preferable that it is 5-30 mol%. Since the crosslinking density of the block resin can be adjusted to an appropriate value by adding the compound (B), various physical properties as the pressure-sensitive adhesive can be further improved. If it is less than 1 mol%, the cohesive force and heat resistance may be insufficient, and if it exceeds 50 mol%, the crosslink density becomes too high and good mechanical properties may not be obtained. In particular, when used as a pressure-sensitive adhesive composition for laminating optical members, good mechanical properties may not be obtained.

  Examples of the functional group capable of reacting with a hydroxyl group in the compound (B) include an isocyanate group, a methylol group, and an acid anhydride group. Examples thereof include polyisocyanate compounds, amino resins, phenol resins, and polyfunctional polycarboxylic acid anhydrides.

  A polyisocyanate compound is a compound having two or more isocyanate groups. The isocyanate group in the polyisocyanate compound can react with a reactive functional group of the block resin, such as a hydroxyl group or a carboxyl group.

  The polyisocyanate compound is not particularly limited as long as it is a compound having a plurality of isocyanate groups in the molecule. Examples of polyisocyanate compounds include tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, tetramethylxylylene diisocyanate, naphthalene diisocyanate, triphenylmethane trisene. Polyisocyanate compounds such as isocyanate and polymethylene polyphenyl isocyanate, adducts of these polyisocyanate compounds and polyol compounds such as trimethylolpropane, burettes and isocyanurates of these polyisocyanate compounds, and further these polyisocyanate compounds Known polyether polyols and polymers Ester polyols, acrylic polyols, polybutadiene polyols, adducts, etc. and polyisoprene polyol and the like.

  Examples of amino resins and phenol resins include addition compounds of urea, melamine, benzoguanamine, phenol, cresols, bisphenols, and the like with formaldehyde, or partial condensates thereof.

  The polyfunctional polycarboxylic acid anhydride is a compound having two or more carboxylic acid anhydride groups and is not particularly limited, but tetracarboxylic dianhydride, hexacarboxylic dianhydride, hexacarboxylic dianhydride And polyvalent carboxylic acid anhydrides such as maleic anhydride copolymer resins. In addition, polycarboxylic acid, polycarboxylic acid ester, polycarboxylic acid half ester, and the like that can be converted into anhydrides via a dehydration reaction during the reaction are compounds having two or more carboxylic acid anhydride groups in the present invention. included.

  More specifically, as tetracarboxylic dianhydride, pyromellitic anhydride, benzophenone tetracarboxylic dianhydride, biphenyl tetracarboxylic dianhydride, oxydiphthalic dianhydride, diphenyl sulfone tetracarboxylic dianhydride, Diphenyl sulfide tetracarboxylic dianhydride, butane tetracarboxylic dianhydride, perylene tetracarboxylic dianhydride, naphthalene tetracarboxylic dianhydride, "Ricacid TMTA-C", "Ricacid MTA-" manufactured by Shin Nippon Chemical Co., Ltd. 10 ”,“ Licacid MTA-15 ”,“ Licacid TMEG series ”,“ Licacid TDA ”, and the like.

  Examples of maleic anhydride copolymer resins include SMA resin series manufactured by Sartomer, GSM series manufactured by Gifu Shellac Co., Ltd., styrene-maleic anhydride copolymer resins, p-phenylstyrene-maleic anhydride copolymer resins, polyethylene- Α-olefin-maleic anhydride copolymer resins such as maleic anhydride, “VEMA” (copolymer of methyl vinyl ether and maleic anhydride) manufactured by Daicel Chemical Industries, Ltd., and acrylic anhydride-modified polyolefin (“aurolen series”) ": Nippon Paper Chemical Co., Ltd.), maleic anhydride copolymer acrylic resin, and the like.

  These compounds (B) may be used alone or in combination of two or more.

  The curing catalyst is appropriately selected depending on the curing agent to be used, and a known curing catalyst species, addition amount, and curing time are selected. Further, the curing agent may be added at the time of resin synthesis if there is no problem in handling the pressure-sensitive adhesive composition.

  The organic solvent used in the pressure-sensitive adhesive composition of the present invention is not limited as long as the block resin dissolves, but is not limited to aliphatic hydrocarbons such as cyclohexane and n-heptane, and aromatic carbonization such as toluene and xylene. Hydrogens, acetone, methyl ethyl ketone, methyl isobutyl ketone, diacetone alcohol, diisobutyl ketone, ketones such as cyclohexanone, alcohols such as isopropyl alcohol and n-butyl alcohol, acetic acid such as ethyl acetate, butyl acetate, isoamyl acetate and ethyl lactate Glycol esters such as esters, propylene glycol monomethyl ether, ethyl cellosolve, butyl cellosolve, propylene glycol monomethyl ether acetate, cellosolve acetate, methoxybutyl acetate Kind and the like.

  Moreover, you may add well-known additives, such as a silane coupling agent, an organic filler, an inorganic filler, antioxidant, a ultraviolet absorber, a plasticizer, a tackifier, to an adhesive composition.

  In the pressure-sensitive adhesive composition of the present invention, one or more types may be used as long as they do not impede the purpose of the present invention in order to achieve tackiness, blocking prevention, curling prevention, surface gloss adjustment, weather resistance improvement, wettability improvement, and the like. Two or more other resins can be blended.

  Furthermore, a known thermosetting resin, a photocurable resin, or the like can be added to the pressure-sensitive adhesive composition of the present invention to impart physical property control, photocurability, or the like.

  Examples of other resins include acrylic resin, polyamide, epoxy resin, polyurethane resin, polyvinyl acetate, polyvinyl acetal, polystyrene, fluororesin, polycarbonate, polyether, polyisobutylene, petroleum resin, rosin, nitrocellulose, sucrose ester, Thermoplastic resins such as vinyl chloride / vinyl acetate copolymers, ethylene / vinyl acetate copolymers, α-olefin / maleic anhydride copolymers, styrene / maleic anhydride copolymers, phenol resins, urea Cured with ultraviolet rays or electron beams such as resin, melamine resin, amino resin, polyester resin, alkyd resin, silicon resin, epoxy resin, epoxy acrylate, polyester acrylate, urethane acrylate, polyether acrylate, phosphazene resin, etc. That there is a resin, it may be blended these one or more. If necessary, fillers such as talc, calcium carbonate, titanium oxide, tackifiers, UV absorbers, fluorescent dyes such as fluorescent brighteners, colored dyes, colorants, thickeners, antifoaming agents, One or more additives such as a leveling agent, an anti-crater agent, an anti-settling agent, an antioxidant, a light stabilizer, a flame retardant, a wax, and a heat stabilizer can be added as appropriate.

  Various pressure-sensitive adhesive sheets can be obtained using the pressure-sensitive adhesive composition of the present invention. For example, a pressure-sensitive adhesive sheet can be obtained by applying a pressure-sensitive adhesive composition to various sheet-like substrates, drying and curing the sheet. Examples of the sheet-like base material include so-called plate-like and film-like materials such as paper, metal plate, synthetic resin film, and glass plate, rod-like materials, and other various shapes. Various base materials can be used alone or in a multi-layered state in which a plurality of base materials are laminated. Further, the surface can be peeled off. Examples of the metal plate include a stainless steel plate, an aluminum plate, a steel plate, and a copper plate. Examples of the synthetic resin film include synthetic resin films such as polyethylene film, polypropylene film, cycloolefin film, polyester film, and triacetate film.

  When using the adhesive composition of this invention, formation of an adhesive layer can be performed using the coating device currently used normally. Examples of the coating apparatus include a roll knife coater, a die coater, a roll coater, a bar coater, a gravure roll coater, a reverse roll coater, dipping, a blade coater, and the like. In addition, the dry film thickness of the pressure-sensitive adhesive layer is 5 to 100 μm in consideration of an appropriate film thickness and economy for absorbing and relaxing stress concentration caused by expansion and contraction of a sheet-like optical member represented by a polarizing plate. It is preferable that

  The pressure-sensitive adhesive composition of the present invention can be made into a laminate for an optical member by applying it to the optical member. The laminate of the present invention is a so-called sheet (or film) optical member having optical characteristics such as a polarizing film, a retardation film, an elliptically polarizing film, an antireflection film, and a brightness enhancement film. The pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition is laminated. On the other surface of the pressure-sensitive adhesive layer, a sheet-like base material subjected to a release treatment can be laminated. The laminate of the present invention is (a) coating and drying the pressure-sensitive adhesive composition on the release-treated surface of the release-treated sheet-like substrate, and laminating the sheet-like optical member on the surface of the pressure-sensitive adhesive layer, (B) It can be obtained by coating and drying the pressure-sensitive adhesive composition on the sheet-like optical member and laminating the release-treated surface of the release-like sheet-like substrate on the surface of the pressure-sensitive adhesive layer. . A curing agent can be blended in the pressure-sensitive adhesive composition, but the curing reaction between the block resin and a curing agent such as a polyisocyanate compound is carried out by drying the pressure-sensitive adhesive composition, and forming a sheet-like optical member on the surface of the pressure-sensitive adhesive layer. It progresses at the time of laminating | stacking the sheet-like base material by which the peeling process was carried out, and laminating | stacking.

  The sheet-like optical member is obtained by peeling off the release-treated sheet-like base material covering the surface of the pressure-sensitive adhesive layer from the laminate thus obtained, and sticking the pressure-sensitive adhesive layer to the glass member for a liquid crystal cell. It is possible to obtain a liquid crystal cell member having a configuration of: / pressure-sensitive adhesive layer / liquid crystal cell glass member.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples. In the examples, “part” means “part by weight”, and “%” means “% by weight”. Further, the weight average molecular weight Mw of the resin is a value in terms of polystyrene determined by GPC measurement.

<Synthesis Example 1>
In a four-necked flask equipped with a thermometer, a stirrer, a reflux condenser, and a nitrogen gas inlet tube, 20 parts of methyl ethyl ketone, 7.1 parts of methyl methacrylate, 0.9 parts of 2-hydroxyethyl methacrylate, 0.4 ethyl bromoisobutyrate And 0.6 parts of tetramethylethylenediamine were charged, the temperature was raised to 40 ° C., and nitrogen was introduced for 30 minutes. 0.3 parts of cuprous chloride was added, and the temperature was raised to 70 ° C. under a nitrogen stream to initiate polymerization. After polymerization for 2 hours, the polymerization solution was sampled, and it was confirmed that the polymerization yield was 95% or more from the dry solid content of the solution (block [X] Mw = 5400, Mw / Mn = 1.2). Next, 55 parts of lauryl methacrylate, 29 parts of ethylhexyl methacrylate and 27 parts of methyl ethyl ketone were added and the temperature was raised to 80 ° C. Further, after polymerization for 4 hours, the polymerization solution was sampled, and it was confirmed that the polymerization yield was 96% or more from the dry solid content of the solution (block [X]-[Y] Mw = 45100, Mw / Mn = 1.2 ). Further, 7.1 parts of methyl methacrylate, 0.9 part of 2-hydroxyethyl methacrylate, and 20 parts of methyl ethyl ketone were added to perform polymerization for 2 hours (block [X]-[Y]-[Z] Mw = 55100, Mw / Mn = 1.3). The final polymerization yield calculated from the dry solid content of the solution was 97%.

  After 83 parts of methyl ethyl ketone was added to the polymerization solution and cooled to room temperature, 24 parts of cation exchange resin Diaion PK228LH (manufactured by Mitsubishi Chemical) was added and stirred for 1 hour. 1 part was added and stirred for 1 hour. The cation exchange resin and the acid adsorbent were removed by filtration, and the polymerization solution was concentrated to obtain a light yellow transparent block resin (a).

<Synthesis Example 2>
Synthesis of the block [X] of Synthesis Example 1 is 7.6 parts of methyl methacrylate and 0.9 part of 2-hydroxyethyl methacrylate, and the synthesis of the block [Y] is 67 parts of lauryl methacrylate and 16 parts of ethylhexyl methacrylate and the block [Z]. A block resin (b) was obtained in the same manner except that the synthesis was changed to 7.6 parts of methyl methacrylate and 0.9 parts of 2-hydroxyethyl methacrylate.

<Synthesis Example 3>
The synthesis of the block [X] of Synthesis Example 1 is 37.6 parts of normal butyl methacrylate and 0.9 part of 2-hydroxyethyl methacrylate, the synthesis of the block [Y] is 56.6 parts of lauryl methacrylate, and 0.2 parts of 2-hydroxyethyl methacrylate. A block resin (c) was obtained in the same manner except that the synthesis of the two-part block [Z] was changed to 3.8 parts of normal butyl methacrylate and 0.9 part of 2-hydroxyethyl methacrylate.

<Synthesis Example 4>
Synthesis of block [X] of Synthesis Example 1 was 6.8 parts of methyl methacrylate and 0.2 part of 2-hydroxyethyl methacrylate, and synthesis of block [Y] was 18 parts of isodecyl methacrylate and 68 parts of ethylhexyl methacrylate, block [Z]. The block resin (d) was obtained in the same manner except that the synthesis of was changed to 6.8 parts of methyl methacrylate and 0.2 part of 2-hydroxyethyl methacrylate.

<Synthesis Example 5>
Synthesis of the block [X] of Synthesis Example 1 was performed by using 3.2 parts of methyl methacrylate and 2.9 parts of 2-hydroxypropyl methacrylate, and the synthesis of the block [Y] by 86.7 parts of lauryl methacrylate and 1.3 parts of 2-hydroxypropyl methacrylate. The block resin (e) was obtained in the same manner except that the synthesis of the block and the block [Z] was changed to 3.2 parts of til methacrylate and 2.9 parts of 2-hydroxypropyl methacrylate.

<Synthesis Example 6>
Synthesis of the block [X] of Synthesis Example 1 is 8.1 parts of methyl methacrylate, 4.4 parts of 2-hydroxyethyl methacrylate, and the synthesis of the block [Y] is 64 parts of lauryl methacrylate and 11 parts of ethylhexyl methacrylate, and the block [Z] A block resin (f) was obtained in the same manner except that the synthesis was changed to 8.1 parts of methyl methacrylate and 4.4 parts of 2-hydroxyethyl methacrylate.

<Synthesis Example 7>
Synthesis of block [X] of Synthesis Example 1 was 7.5 parts of methyl methacrylate, 0.01 part of 2-hydroxyethyl methacrylate, synthesis of block [Y] was 58 parts of lauryl methacrylate and 27 parts of ethylhexyl methacrylate, and block [Z] A block resin (g) was obtained in the same manner except that the synthesis was changed to 7.5 parts of methyl methacrylate and 0.01 parts of 2-hydroxyethyl methacrylate.

<Synthesis Example 8>
Synthesis of block [X] in Synthesis Example 1 is 1.7 parts of methyl methacrylate, 1.1 parts of 2-hydroxyethyl methacrylate, synthesis of block [Y] is 94.4 parts, and synthesis of block [Z] is methyl. A block resin (h) was obtained in the same manner except that it was changed to 1.7 parts of methacrylate and 1.1 parts of 2-hydroxyethyl methacrylate.

<Synthesis Example 9>
Synthesis of block [X] in Synthesis Example 1 was 47.2 parts of ethyl methacrylate and 0.9 part of 2-hydroxyethyl methacrylate, and synthesis of block [Y] was 35.7 parts of lauryl methacrylate and 0. 2-hydroxyethyl methacrylate. The block resin (i) was obtained in the same manner except that 9 parts and the synthesis of the block [Z] were changed to 14.4 parts of ethyl methacrylate and 0.9 parts of 2-hydroxyethyl methacrylate.

<Synthesis Example 10>
The synthesis of the block [X] in Synthesis Example 1 is 9.6 parts of ethylhexyl methacrylate and 0.8 parts of 2-hydroxyethyl methacrylate, the synthesis of the block [Y] is 48 parts of lauryl methacrylate and 31 parts of ethylhexyl methacrylate, and the block [Z]. A block resin (j) was obtained in the same manner except that the synthesis was changed to 9.6 parts of ethylhexyl methacrylate and 0.8 parts of 2-hydroxyethyl methacrylate.

<Synthesis Example 11>
Synthesis of block [X] in Synthesis Example 1 is 12.8 parts of methyl methacrylate, 2.2 parts of 2-hydroxyethyl methacrylate, synthesis of block [Y] is 70 parts of normal butyl methacrylate, and synthesis of block [Z] is methyl methacrylate. A block resin (k) was obtained in the same manner except that the procedure was changed to 12.8 parts and 2.2 parts of 2-hydroxyethyl methacrylate.

<Synthesis Example 12>
In Synthesis Example 1, 1.6 parts of hydroxyhydroxybutyl 4-bromopropionate instead of ethyl bromoisobutyrate, 3.3 parts of bipyridine instead of tetramethylethylenediamine, 1.0% cuprous bromide instead of copper chloride The block [X] was synthesized using 99 parts of normal butyl acrylate, the block [Y] was synthesized using 1.0 part of 4-hydroxybutyl acrylate, and the block [Z] was not synthesized. Except for the above, a block resin (l) was obtained in the same manner.

<Synthesis Example 13>
Synthesis of block [X] of Synthesis Example 1 is 11 parts isobutyl methacrylate, 11 parts 2-hydroxypropyl methacrylate, synthesis of block [Y] is 50 parts isobutyl methacrylate, and synthesis of block [Z] is 28 parts 2-hydroxypropyl methacrylate. A block resin (m) was obtained in the same manner except that the procedure was changed.

  Table 1 shows the resins synthesized above. In addition, the glass transition temperature of the homopolymer by the monomer used for the synthesis is described in the column.

Methyl methacrylate: 105 ° C
Ethyl methacrylate: 65 ° C
Isobutyl methacrylate: 67 ° C
Normal butyl methacrylate: 20 ° C
Lauryl methacrylate: -65 ° C
Ethylhexyl methacrylate: -10 ° C
Isodecyl methacrylate: -41 ° C
Hydroxyethyl methacrylate: 55 ° C
Hydroxypropyl methacrylate: 26 ° C

<Examples 1-7 and Comparative Examples 1-9>
As shown in Table 2, a curing agent was added to the mixture of 100 parts of the acrylic resin obtained in Synthesis Examples 1 to 13 and 70 parts of ethyl acetate, and the mixture was stirred well to obtain an adhesive composition. The pressure-sensitive adhesive composition was applied to release paper in an amount of 20 g / m ² using an applicator and dried at 100 ° C. for 2 minutes to prepare a coated product. What passed 1 week at 25 degreeC was used for the following measurements. The results are also shown in Table 2.

The test method of the pressure-sensitive adhesive composition is as follows.
<Adhesive strength>
The pressure-sensitive adhesive sheet coated with the resin solution on the release paper is transferred to a PET film (film thickness 50 μm), pasted on a glass plate at 23 ° C. and 65% RH, roll-bonded according to JIS, and after 20 hours. The peel strength (180 degree peel, tensile speed 300 mm / min; unit g / 25 mm width) was measured with a shopper type peel tester. Moreover, the remaining condition of the resin on the glass plate after peeling was evaluated from 5 (good) to 1 (bad).

<Moisture and heat resistance / optical properties (light leakage prevention)>
The pressure-sensitive adhesive sheet produced as described above was transferred to one side of a polarizing film, and the polarizing film was subjected to pressure-sensitive adhesive processing. This adhesive-processed polarizing film was aged at a temperature of 23 ° C. and a relative humidity of 50% for 1 week to obtain a polarizing plate. The adhesive-processed polarizing plate was cut into a size of 150 mm × 80 mm, and attached to both surfaces of a 1.1 mm thick float glass plate using a laminator so that the absorption axes of the polarizing plates were orthogonal to each other. Subsequently, the glass plate with the polarizing plate attached thereto was held in an autoclave at 50 ° C. and 5 atm for 20 minutes to be in close contact with the glass plate. Further, the composition of the polarizing plate and the glass plate was allowed to stand for 100 hours at 80 ° C. and 90% relative humidity for 100 hours after foaming, floating peeling (moisture and heat resistance), and left for 100 hours at 80 ° C. and 90% relative humidity for 100 hours. Light leakage when light was transmitted through the components of the polarizing plate and the glass plate was visually observed and evaluated in three stages.

◎ "No foaming, floating peeling, or light leakage"
○ “Slight foaming, floating peeling, light leakage is recognized, but there is no practical problem”
△ means that there are obvious problems of floating peeling and light leakage.

Curing agent: ethyl acetate solution of XDI / TMP (trimethylopropane propane adduct of xylylene diisocyanate) NCO value 103 mg KOH / g
As shown in Table 2, the pressure-sensitive adhesive compositions of Examples 1 to 7 have adhesive strength and holding power, and have little adhesive residue after peeling. Furthermore, it was shown that it was excellent in light leakage prevention properties and suitable for optical applications requiring moisture and heat resistance. On the other hand, in Comparative Examples 1 to 9, it was shown that the light leakage prevention property was particularly poor and there was no suitability for optical applications.

  The pressure-sensitive adhesive composition of the present invention is useful as a pressure-sensitive adhesive composition for optical members that cause heat shrinkage, particularly for polarizing film bonding, because it has adhesive strength, has excellent light leakage prevention properties, and exhibits good holding power. .

Claims (8)

The hydroxyl value obtained by polymerizing an ethylenically unsaturated monomer containing an ethylenically unsaturated monomer (A) having a hydroxyl group is 0.3 to 30 mgKOH / g, and is represented by [X]-[Y]-[Z]. A block resin having a structure
A pressure-sensitive adhesive composition comprising a compound (B) having at least two functional groups capable of reacting with a hydroxyl group,
Blocks [X] and [Z] of the block resin are blocks each having a glass transition temperature (Tg) of 10 ° C. or higher independently, and block [Y] is a block having a glass transition temperature (Tg) of −10 ° C. or lower. And
The weight ratio of the blocks [X], [Y] and [Z] is [X] 3 to 40% by weight, [Y] 50 to 94% by weight, [Z] 3 to 40% by weight, and
80 to 100% by weight of the ethylenically unsaturated monomer (A) having a hydroxyl group is contained in the blocks [X] and [Z].   The pressure-sensitive adhesive composition according to claim 1, wherein the block resin has a glass transition temperature (Tg) of -55 to 0 ° C.   The pressure-sensitive adhesive composition according to claim 1 or 2, wherein the block resin has a weight average molecular weight (Mw) of 3000 to 300,000.   The pressure-sensitive adhesive composition according to any one of claims 1 to 3, wherein the polydispersity [weight average molecular weight (Mw) / number average molecular weight (Mn)] of the block resin is 1.1 to 2.5.   The pressure-sensitive adhesive composition according to any one of claims 1 to 4, wherein the block resin is polymerized by an atom transfer radical polymerization method.   The functional group capable of reacting with a hydroxyl group in the compound (B) having at least two functional groups capable of reacting with a hydroxyl group is 1 to 50 mol% with respect to the hydroxyl group in the block resin. Adhesive composition.   The laminated body by which an optical member is laminated | stacked on the adhesive layer formed from the adhesive composition in any one of Claims 1-6.   The glass member for liquid crystal cells, the adhesive layer formed from the adhesive composition in any one of Claims 1-6, and the member for liquid crystal cells laminated | stacked sequentially.