Pressure-sensitive adhesive polarizing plate

Abstract

As a pressure-sensitive adhesive polarizing plate, for example, a pressure-sensitive adhesive polarizing plate allowing a pressure-sensitive adhesive layer in the polarizing plate to have an excellent interfacial adhesion with another layer and have no detachment phenomenon can be provided in the present application.

Claims

1. A pressure-sensitive adhesive polarizing plate, comprising: a polarizer; and a pressure-sensitive adhesive layer which is formed on one surface of the polarizer and formed of a cross-linkable composition comprising an acrylic pressure-sensitive adhesive resin and includes a polyalkylene polyol compound having 3 or more hydroxyl groups, wherein the polyalkylene polyol compound is represented by the following Formula 1 and wherein the polyalkylene polyol compound has a weight average molecular weight of 30,000 or less:
(HO.sub.nAB).sub.m[Formula 1] where A is a core including a polyalkylene oxide unit, B is a chain represented by the following Formula 2, m is an integer of 1 or more, n is an integer of 0 or more, and the sum (m+n) of m and n is 3 or more:
L.sub.1-Q.sub.1-L.sub.2O-A.sub.1.sub.x.sub.yL.sub.3-Q.sub.2-L.sub.4A.sub.2-O.sub.z-A.sub.3-OH[Formula 2] where A.sub.1 to A.sub.3 each independently represent an alkylene group, Q.sub.1 and Q.sub.2 represent an aliphatic or aromatic divalent residue, L.sub.1 to L.sub.4 represent linkers, x is an integer of 1 or more, y is an integer of 0 or more, and z is an integer of 1 or more.

2. The pressure-sensitive adhesive polarizing plate of claim 1, wherein the acrylic pressure-sensitive adhesive resin includes a carboxyl group, and the pressure-sensitive adhesive layer further includes a crosslinking agent.

3. The pressure-sensitive adhesive polarizing plate of claim 1, wherein the polyalkylene polyol compound includes a polyalkylene oxide unit represented by the following Formula 3: ##STR00009## where L is a linear or branched alkylene group having 2 to 12 carbon atoms.

4. The pressure-sensitive adhesive polarizing plate of claim 1, wherein the core of the compound of Formula 1 has a weight average molecular weight in a range of 1,000 to 10,000.

5. The pressure-sensitive adhesive polarizing plate of claim 1, wherein the core (A) of Formula 1 includes a polyethylene oxide unit and a polypropylene oxide unit.

6. The pressure-sensitive adhesive polarizing plate of claim 5, wherein a ratio (P/E) of a number of moles (P) of the polypropylene oxide unit to a number of moles (E) of the polyethylene oxide unit in the core is in a range of 1 to 10.

7. The pressure-sensitive adhesive polarizing plate of claim 1, wherein one or more of the linkers of Formula 2 is an oxygen atom, a sulfur atom, an alkylene group, an alkenylene group or an alkynylene group, or is represented by the following Formula 4 or 5: ##STR00010## where R.sub.1 and R.sub.2 each independently represent a hydrogen atom or an alkyl group.

8. The pressure-sensitive adhesive polarizing plate of claim 1, wherein the pressure-sensitive adhesive layer further includes an ionic compound.

9. The pressure-sensitive adhesive polarizing plate of claim 8, wherein the ionic compound has an octanol-water partition coefficient of 4 or more.

10. The pressure-sensitive adhesive polarizing plate of claim 8, wherein the ionic compound has a cation with a cation-water binding energy in a range of 0 to 0.6 Kcal/mol.

11. The pressure-sensitive adhesive polarizing plate of claim 1, wherein the pressure-sensitive adhesive layer further includes an isocyanate compound.

12. A pressure-sensitive adhesive layer-coated polarizing plate, comprising at least: a polarizing film having a transparent protective film formed on one or both surfaces of a polarizer; and a pressure-sensitive adhesive layer, wherein the pressure-sensitive adhesive layer is formed of a pressure-sensitive adhesive composition containing a (meth)acrylic polymer and an ionic compound with an anion component and a cation component, the (meth)acrylic polymer is an aromatic ring-containing (meth)acrylic polymer having an aromatic ring-containing alkyl (meth)acrylate as a monomer unit, and the pressure-sensitive adhesive composition further includes a polyalkylene polyol compound having 3 or more hydroxyl groups, wherein the polyalkylene polyol compound is represented by the following Formula 1 and wherein the polyalkylene polyol compound has a weight average molecular weight of 30,000 or less: ##STR00011## where A is a core including a polyalkylene oxide unit, B is a chain represented by the following Formula 2, m is an integer of 1 or more, n is an integer of 0 or more, and the sum (m+n) of m and n is 3 or more: ##STR00012## where A.sub.1 to A.sub.3 each independently represent an alkylene group, Q.sub.1 and Q.sub.2 represent an aliphatic or aromatic divalent residue, L.sub.1 to L.sub.4 represent linkers, x is an integer of 1 or more, y is an integer of 0 or more, and z is an integer of 1 or more.

Description

BRIEF EXPLANATION OF DRAWING

(1) FIGS. 1 and 2 show infrared (IR) spectrum results for compounds prepared in Preparation Examples 2 and 3.

EFFECT

(2) The present application relates to a pressure-sensitive adhesive polarizing plate. In one embodiment, the pressure-sensitive adhesive layer included in the pressure-sensitive adhesive polarizing plate of the present application shows an excellent interfacial adhesion and has no detachment phenomenon.

EMBODIMENTS

(3) Hereinafter, the present invention will be explained in detail with reference to examples and comparative examples, but it is to be noted that the range of the pressure-sensitive adhesive composition is not limited to the following examples.

(4) 1. Infrared (IR) Spectrometry

(5) Conditions for measuring an IR spectrum applied in the present specification are as follows. The spectrum baseline is air during the measurement.

(6) <Measurement Conditions>

(7) Measuring instrument: Agilent Cary 660 FTIR Spectrometer

(8) ATR: PIKE Technologies 025-2018 Miracle ZnSe performance crystal plate

(9) Measurement wavelength: 400 to 4000 nm

(10) Measurement temperature: 25 C.

(11) 2. Evaluation of Molecular Weight

(12) A weight average molecular weight (Mn) was measured under the following conditions using GPC. In preparing calibration curves, the measuring results were converted using standard polystyrene in an Agilent system.

(13) <Measurement Conditions>

(14) Measuring instrument: Agilent GPC (Agilent 1200 series, U.S.)

(15) Column: connected two PL Mixed B

(16) Column temperature: 40 C.

(17) Eluent: tetrahydrofuran (THF)

(18) Flow rate: 1.0 mL/min

(19) Concentration: 1 mg/mL (100 L injection)

(20) 3. Measurement of Acid Value

(21) An acid value was measured using an automatic titration device (COM-550, manufactured by HIRANUMA SANGYO Co., Ltd.), and calculated by the following equation:
A={(YX)f5.611}/M

(22) A; an acid value

(23) Y; a titration amount (ml) of a sample solution

(24) X; a titration amount (ml) of a solution containing 50 g of a mixed solvent

(25) f; a factor of a titration solution

(26) M; a weight (g) of a polymer sample

(27) Measurement conditions were as follows.

(28) Sample solution: prepared by dissolving about 0.5 g of a polymer sample in 50 g of a mixed solvent (toluene/2-propanol/distilled water=50/49.5/0.5, weight ratio)

(29) Titration solution: 0.1N, 2-propanol-type potassium hydroxide solution (manufactured by Wako Junyaku Kogyo Co., Ltd., for test neutralization value of petroleum products)

(30) Electrode: glass electrode, GE-101, Comparative electrode: RE-201

(31) Measurement mode: for test neutralization value of petroleum products

(32) 4. Measurement of Octanol-Water Partition Coefficient

(33) The octanol-water partition coefficient (log P) was calculated using COSMOtherm (version C30_1301, COSMOlogic) which is a commercial thermodynamic program. The surface charge distribution of each compound and the difference in chemical potential of water and octanol was calculated using the program, and thereby the partition coefficient (log P) was obtained. In this process, the BP_TZVP_C30_1301 parameterization was applied.

(34) 5. Measurement of Binding Energy

(35) The binding energy was calculated using DMoL3 (Materials Studio DMoL3 version 6.1) which is a density functional theory (DFT) calculation package manufactured by BIOVIA. BP functional/DNP basis was used as a calculation level.

(36) Two materials to be a target of the binding energy were modeled at a single molecule level to obtain the optimized structure of the case where two materials each exist in a gas phase and the case where they are bound, and a difference in energy of the two cases was calculated as a binding energy.

(37) 6. Measurement of Mixing Energy

(38) The mixing energy was calculated using COSMOtherm (version C30_1301) which is a COSMO-RS theory calculation package and Turbomole (version 6.5) which is a DFT calculation package manufactured by COSMOlogic GmbH & Co. KG. In COSMOtherm, the BP_TZVP_C30_1301 parameterization was used, and BP functional/def-TZVP basis was used in Turbomole. Each material to be a target of the mixing energy was modeled at a single molecule level, and the optimum structure and surface screening charge were calculated in the environment in which the surrounding dielectric constant was infinite using a Turbomole package, and based on this, a difference between chemical potential in the case where each material independently exists and chemical potential in the case where they are mixed was calculated as a mixing energy. In the case of log P, a mixing energy was also calculated using COSMOtherm after the same process was carried out.

(39) 7. Measurement of Durability

(40) A polarizing plate of examples or comparative examples was cut to a size of about 262 mmabout 465 mm (widthlength) to prepare a specimen of two sheets, and two sheets of the specimen thus prepared were attached to both surfaces of a glass substrate with the optical absorbing axes of each polarizing plate crossed, thereby preparing a sample. The pressure applied on attaching was about 5 Kg/cm.sup.2 and this work was performed in a clean room such that no bubbles or foreign material was introduced.

(41) Durability of the sample was evaluated by heat resistant durability and moisture-heat resistant durability. The moisture-heat resistant durability was evaluated after leaving the sample at a temperature of 60 C. and a relative humidity of 90% for about 500 hours, and the heat resistant durability was evaluated after leaving the sample at a temperature of 80 C. for 500 hours.

(42) The evaluation criteria of durability are as follows.

(43) <Evaluation Criteria>

(44) O: No bubbles and peeling observed when evaluating heat resistant and moisture-heat resistant durability

(45) : A few bubbles and/or peeling observed when evaluating heat resistant and/or moisture-heat resistant durability

(46) X: Many bubbles and/or peeling observed when evaluating heat resistant and/or moisture-heat resistant durability

(47) 8. Measurement of Surface Resistance of Pressure-Sensitive Adhesive Layer

(48) The polarizing plate prepared in examples or comparative examples was left under room temperature conditions of 25 C. and 50% RH for 7 days and the surface resistance (initial surface resistance) was measured. The surface resistance was measured after removing a release film from the polarizing plate, and applying a voltage of 500 V for 1 minute under an environment of 23 C. and 50% RH using HIRESTA-UP (MCP-HT450; manufactured by Mitsubishi Chemical Corporation). The sample (pressure-sensitive adhesive polarizing plate) was left at 80 C. for 1,000 hours to measure the surface resistance of the sample in heat resistance conditions, and the sample (pressure-sensitive adhesive polarizing plate) was left at 60 C. and 90% RH for 1,000 hours to measure the surface resistance of the sample in hygrothermal resistance conditions. The samples left in heat resistance and hygrothermal resistance conditions as above were subjected to evaluation after leaving each specimen at room temperature for 24 hours.

(49) 9. Evaluation of Haze

(50) The haze was evaluated by observing the condition of a coating solution with the naked eye just after coating the pressure-sensitive adhesive composition prepared in examples or comparative examples. The evaluation was conducted according to the following criteria.

(51) <Evaluation Criteria>

(52) O: No haze observed

(53) : Slight haze observed

(54) X: Severe haze observed

(55) 10. Evaluation of Peel Strength

(56) The pressure-sensitive adhesive polarizing plate prepared in examples or comparative examples was cut to a size of 25 mm120 mm (widthlength) and attached to a glass substrate by the medium of a pressure-sensitive adhesive layer.

(57) After 4 hours of attachment, the polarizing plate was gradually peeled from the glass substrate at a peeling angle of 180 degrees and a peeling speed of 300 mm/min to measure peel strength (initial peel strength). Furthermore, the polarizing plate was left at 50 C. for 4 hours after the attachment, and peel strength (50 C. peel strength) was measured in the same manner.

(58) 11. Evaluation of Substrate Adhesion

(59) The substrate adhesion (adhesion between a pressure-sensitive adhesive layer and a polarizing plate protective film (TAC film)) of the pressure-sensitive adhesive polarizing plate was evaluated by the following method. A strong adhesive tape was first attached onto a surface of a pressure-sensitive adhesive layer formed on one surface of the pressure-sensitive adhesive polarizing plate. The strong adhesive tape was peeled from the pressure-sensitive adhesive polarizing plate within 1 minute after lamination, an amount of the pressure-sensitive adhesive layer remaining on a surface of the polarizing plate after peeling was measured and classified based on the following criteria.

(60) <Evaluation Criteria>

(61) O: Pressure-sensitive adhesive layer remained on 90% or more of the total area of the polarizing plate

(62) : Pressure-sensitive adhesive layer remained on 50% or more and less than 90% of the total area of the polarizing plate

(63) X: Pressure-sensitive adhesive layer remained on less than 50% of the total area of the polarizing plate

(64) 12. Release Peel Strength at Room Temperature

(65) The pressure-sensitive adhesive polarizing plate prepared in examples or comparative examples was cut to a size of 50 mm120 mm (widthlength). Thereafter, a surface of the cut pressure-sensitive adhesive polarizing plate with no pressure-sensitive adhesive layer was attached to a glass substrate using double-sided tape. Then, a release film on the pressure-sensitive adhesive layer was peeled at a peeling angle of 180 degrees and a peeling speed of 300 mm/min to measure peel strength (initial peel strength).

Preparation Example 1. Preparation of Acrylic Pressure-Sensitive Adhesive Resin Solution

(66) In a 1 L reactor with nitrogen gas refluxed and a cooling device installed to easily regulate a temperature, n-butyl acrylate (BA) and acrylic acid (AA) were introduced in a weight ratio (BA:AA) of 94:6, and ethyl acetate was also introduced therein as a solvent. Subsequently, oxygen was removed by purging with nitrogen gas for 1 hour, and a reaction initiator (AIBN: azobisisobutyronitrile) was introduced and reacted for about 8 hours. Then, the reactants were diluted with ethyl acetate to prepare an acrylic pressure-sensitive adhesive resin solution having an acid value in a range of about 32 to 34 and a weight average molecular weight of about 1,800,000.

Preparation Example 2. Preparation of Compound (A) of Formula 1

(67) In a reactor with nitrogen gas refluxed and a heater, a cooling device and a thermometer installed to easily regulate a temperature, polyethylene glycol (PEG) with a weight average molecular weight of about 400 and isophorone diisocyanate (IPDI) were introduced in a weight ratio (PEG:IPDI) of about 5:2.8, and a temperature was slowly raised up to about 50 C. and maintained. In such a state, a mixture was uniformly mixed and reacted for about 1 hour. The reaction time was determined by an IR spectrum, and the reaction was continued until an area of an NCO peak found at 2,270 cm.sup.1 in an IR spectrum before reaction decreased to 50%.

(68) Subsequently, the reactants were reacted with a polyol to prepare a compound (A) of Formula 1. In the above description, a polyol compound (HP-3753, manufactured by KPX CHEMICAL CO., LTD.) with a weight average molecular weight of approximately 7,000, which is a triol compound with three terminal hydroxyl groups including a polypropylene oxide unit at 85 wt % and a polyethylene oxide unit at 15 wt %, was used as the polyol.

(69) The polyol compound, the reactants and catalyst (dibutyltin dilaurate) were mixed in a weight ratio (polyol compound:reactants:catalyst) of 92.1:7.8:0.003, and the mixture was gradually added dropwise into a reactor with a temperature maintained to about 60 C. and further reacted, thereby preparing the compound (A) of Formula 1. The reaction was continued until an NCO peak completely disappeared in an IR spectrum.

(70) The compound (A) thus prepared had a molecular weight (Mw) of about 15,200 and a hydroxyl value (OHv) of about 11.2 mgKOH/g. The IR spectrum of the prepared compound is shown in FIG. 1.

Preparation Example 3. Preparation of Compound (B) of Formula 1

(71) In a reactor with nitrogen gas refluxed and a heater, a cooling device and a thermometer installed to easily regulate a temperature, polyethylene glycol (PEG) with a weight average molecular weight of about 400 and isophorone diisocyanate (IPDI) were introduced in a weight ratio (PEG:IPDI) of about 13.6:7.6, and a temperature was slowly raised up to about 50 C. and maintained. In such a state, a mixture was uniformly mixed and reacted for about 1 hour. The reaction time was determined by an IR spectrum, and the reaction was continued until an area of an NCO peak found at 2,270 cm.sup.1 in an IR spectrum before reaction decreased to 50%.

(72) Subsequently, the reactants were reacted with a polyol to prepare a compound (A) of Formula 1. In the above description, a polyol compound (HP-3753, manufactured by KPX CHEMICAL CO., LTD.) with a weight average molecular weight of approximately 7,000, which is a triol compound with three terminal hydroxyl groups including a polypropylene oxide unit at 85 wt % and a polyethylene oxide unit at 15 wt %, was used as the polyol.

(73) The polyol compound, the reactants and catalyst (dibutyltin dilaurate) were mixed in a weight ratio (polyol compound:reactants:catalyst) of 78.9:21.2:0.009,and the mixture was gradually added dropwise into a reactor with a temperature maintained to about 60 C. and further reacted, thereby preparing the compound (B) of Formula 1. The reaction was continued until an NCO peak completely disappeared in an IR spectrum.

(74) The compound (B) thus prepared had a molecular weight (Mw) of about 28,900 and a hydroxyl value (OHv) of about 5.61 mgKOH/g. The IR spectrum of the prepared compound is shown in FIG. 2.

Example 1

(75) As an ionic compound, an ionic compound having methyl tributyl ammonium as a cation and trifluoromethanesulfonyl imide as an anion (octanol-water partition coefficient: about 5.65, cation-water binding energy: 0.45 Kcal/mol) was used. The ionic compound, the acrylic pressure-sensitive adhesive resin of Preparation Example 1, a crosslinking agent, the compound (A) of Preparation Example 2 and an isocyanate compound were mixed to prepare a cross-linkable composition. In the above description, an epoxy crosslinking agent (T-743L, manufactured by Nippon Soken Inc.) was used as the crosslinking agent, a compound (T-760B) prepared by addition polymerization of tolylene diisocyanate and trimethylolpropane was applied as the isocyanate compound. Based on 100 parts by weight of the solid content of the acrylic pressure-sensitive adhesive resin solution, 0.0052 parts by weight of the crosslinking agent, about 0.0793 parts by weight of the compound (A) of Preparation Example 2, about 4 parts by weight of the ionic compound and about 2 parts by weight of the isocyanate compound were mixed. The cross-linkable composition thus prepared was applied onto the release-treated surface of a release-treated poly(ethyleneterephthalate) (PET, MRF-38, manufactured by Mitsubishi Chemical Corporation) film and dried under suitable conditions to form a pressure-sensitive adhesive layer. The pressure-sensitive adhesive layer thus formed was laminated onto one surface of an iodine-based polarizing plate having a triacetyl cellulose (TAC)-based protective film attached to both surfaces thereof, thereby preparing a pressure-sensitive adhesive polarizing plate. The pressure-sensitive adhesive polarizing plate had a structure in which a pressure-sensitive adhesive layer and a release film were sequentially formed on a TAC film of one surface of a polarizing plate (TAC film/iodine-based polarizer/TAC film).

Example 2

(76) A cross-linkable composition, a pressure-sensitive adhesive layer and a pressure-sensitive adhesive polarizing plate were prepared in the same manner as in Example 1 except that the compound (B) of Preparation Example 3 was used instead of the compound (A) of Preparation Example 2.

Example 3

(77) A cross-linkable composition, a pressure-sensitive adhesive layer and a pressure-sensitive adhesive polarizing plate were prepared in the same manner as in Example 1 except that a polyol compound with a weight average molecular weight of approximately 7,000, which is a triol compound with three terminal hydroxyl groups including a polypropylene oxide unit at 85 wt % and a polyethylene oxide unit at 15 wt %, was applied as a polyalkylene glycol polyol instead of the compound (A).

Comparative Example 1

(78) A cross-linkable composition, a pressure-sensitive adhesive layer and a pressure-sensitive adhesive polarizing plate were prepared in the same manner as in Example 1 except that the compound (A) of Preparation Example 2 was not used.

Comparative Example 2

(79) A cross-linkable composition, a pressure-sensitive adhesive layer and a pressure-sensitive adhesive polarizing plate were prepared in the same manner as in Example 1 except that a polypropylene glycol having a weight average molecular weight of about 2,000 and two terminal hydroxyl groups was used instead of the compound (A) of Preparation Example 2.

Comparative Example 3

(80) A cross-linkable composition, a pressure-sensitive adhesive layer and a pressure-sensitive adhesive polarizing plate were prepared in the same manner as in Example 1 except that a polypropylene glycol having a weight average molecular weight of about 6,000 and two terminal hydroxyl groups was used instead of the compound (A) of Preparation Example 2.

Comparative Example 4

(81) A cross-linkable composition, a pressure-sensitive adhesive layer and a pressure-sensitive adhesive polarizing plate were prepared in the same manner as in Example 1 except that a polypropylene glycol having a weight average molecular weight of about 4,000 and three terminal hydroxyl groups was used instead of the compound (A) of Preparation Example 2.

Comparative Example 5

(82) A cross-linkable composition, a pressure-sensitive adhesive layer and a pressure-sensitive adhesive polarizing plate were prepared in the same manner as in Example 1 except that a polypropylene glycol having a weight average molecular weight of about 5,000 and three terminal hydroxyl groups was used instead of the compound (A) of Preparation Example 2.

Comparative Example 6

(83) A cross-linkable composition, a pressure-sensitive adhesive layer and a pressure-sensitive adhesive polarizing plate were prepared in the same manner as in Example 1 except that, as a known plasticizer, a plasticizer (L-7230) having a weight average molecular weight of about 29,000 and one terminal hydroxyl group was used instead of the compound (A) of Preparation Example 2.

Comparative Example 7

(84) A cross-linkable composition, a pressure-sensitive adhesive layer and a pressure-sensitive adhesive polarizing plate were prepared in the same manner as in Example 1 except that a plasticizer (L-7230) having a weight average molecular weight of about 29,000 and one terminal hydroxyl group was used in a ratio of 0.00793 parts by weight.

(85) The results of examples and comparative examples are summarized in the following Table 1.

(86) TABLE-US-00001 TABLE 1 Example 1 2 3 Binding energy (A) 9.46 8.99 9.48 Binding energy (B) 6.50 6.50 6.50 Mixing energy 0.95 0.95 0.95 Substrate adhesion Haze Peel strength at room 700 700 700 temperature (gf/25 mm) 50 C. peel strength 1,200 1,200 1,100 Surface resistance 5.3 5.2 5.9 (10.sup.10 /) Release peel strength 9.7 9.8 9.7 at room temperature (gf/25 mm) Durability Binding energy (A): between polyalkylene polyol compound and acrylic pressure-sensitive adhesive resin (units: Kcal/mol) Binding energy (B): between crosslinking agent and acrylic pressure-sensitive adhesive resin (units: Kcal/mol) Mixing energy: between ionic compound and ethylene oxide unit (units: Kcal/mol)

(87) TABLE-US-00002 TABLE 2 Comparative Example 1 2 3 4 5 6 7 Binding energy (A) 7.84 7.92 8.02 8.25 8.19 8.19 Binding energy (B) 6.50 6.50 6.50 6.50 6.50 6.50 Mixing energy 0.95 0.95 0.95 0.95 0.95 0.95 Substrate adhesion X X X Haze Peel strength at room 450 630 500 500 680 760 600 temperature (gf/25 mm) 50 C. peel strength 1,000 1,300 1,080 1,030 1,250 1,300 1,100 Surface resistance 5.1 5.6 5.6 5.9 5.8 5.9 6.4 (10.sup.10/) Release peel strength at room 13 7.6 9.7 7.9 10 25 11 temperature (gf/25 mm) Durability Binding energy (A): between polyalkylene polyol compound and acrylic pressure-sensitive adhesive resin (units: Kcal/mol) Binding energy (B): between crosslinking agent and acrylic pressure-sensitive adhesive resin (units: Kcal/mol) Mixing energy: between ionic compound and ethylene oxide unit (units: Kcal/mol)