JP2018095807A - Adhesive composition, and adhesive sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive composition capable of obtaining an adhesive sheet which is excellent in an adhesive force, and is excellent in sticking property to an adherend.SOLUTION: An adhesive composition contains an urethane resin (A) having a hydroxyl group, a crosslinking agent (B) and an organic solvent (C), where an adhesive force of an adhesive sheet having a cured film is 1 N/25 mm or more, and a time period from the time at which both ends on a long side of the adhesive sheet of 50 mm×150 mm are held by hand and then the central portion of the adhesive sheet is brought into contact with an adherend until the adherend is separated by hand and the whole adhesive sheet is stuck to the adherend is 10 seconds or less. An adhesive sheet has a cured film of the adhesive composition.SELECTED DRAWING: None

Description

  The present invention relates to a pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet.

  Adhesives are widely used in various fields such as manufacturing scenes of various products such as electronic devices, automobiles, and building materials, and medical products represented by surgical tape.

  There are various properties required for pressure-sensitive adhesives depending on these applications, and one of them has stickiness. For example, a protective adhesive sheet is affixed to building materials used in the construction field in order to prevent scratches on the surface, and can be easily affixed without entraining air from the viewpoint of improving the affixability. An adhesive sheet is required. Moreover, the same easiness of sticking is required also in the adhesive sheet for electronic devices.

  As an adhesive sheet used for the said use, the adhesive sheet formed with the adhesive composition containing an acrylic polymer, an antistatic agent, and a crosslinking agent is disclosed, for example (for example, refer patent document 1). . However, the pressure-sensitive adhesive sheet using an acrylic polymer has excellent adhesive properties but has insufficient adhesiveness (particularly wettability) to an adherend. Thus, there is a demand for a pressure-sensitive adhesive that achieves both physical properties of adhesive and adhesion to an adherend.

JP, 2006-188377, A

  The problem to be solved by the present invention is to provide a pressure-sensitive adhesive composition that provides a pressure-sensitive adhesive sheet that is excellent in adhesive force and excellent in adhesion to an adherend.

  The present invention is a pressure-sensitive adhesive composition containing a urethane resin (A) having a hydroxyl group, a crosslinking agent (B), and an organic solvent (C), and the adhesive strength of the pressure-sensitive adhesive sheet having the cured film is 1N. / 25mm or more, and hold both ends of the long side of the 50mm x 150mm adhesive sheet by hand, contact the center part of the adhesive sheet with the adherend, release the hand, and the entire adhesive sheet is the adherend The pressure-sensitive adhesive composition is characterized in that the time until sticking to is 10 seconds or less.

  Moreover, this invention provides the adhesive sheet characterized by having the cured film of the said adhesive composition.

  The pressure-sensitive adhesive sheet obtained by the pressure-sensitive adhesive composition of the present invention has excellent adhesive strength and adhesiveness to an adherend, and has excellent wettability without involving air on the adherend. Can be attached to the kimono.

  The pressure-sensitive adhesive composition of the present invention is a pressure-sensitive adhesive composition containing a urethane resin (A) having a hydroxyl group, a crosslinking agent (B), and an organic solvent (C), and has a cured film thereof. The adhesive strength of the adhesive sheet is 1 N / 25 mm or more, and both ends of the long side of the 50 mm × 150 mm pressure-sensitive adhesive sheet are held by hand, the center of the pressure-sensitive adhesive sheet is brought into contact with the adherend, and then the hand is released, and the pressure-sensitive adhesive sheet The time until the whole is adhered to the adherend (hereinafter abbreviated as “wetting”) is 10 seconds or less.

  In the present invention, in order to achieve both excellent adhesive force and stickability to the adherend, which is a problem to be solved by the present invention, the adhesive force of the pressure-sensitive adhesive sheet is 1 N / 25 mm or more, and It is essential that the wettability is 10 seconds or less. The adhesive force is preferably in the range of 1 to 20 N / 25 mm, more preferably in the range of 5 to 20 N / 25 mm, from the viewpoint that the balance between adhesive force and adhesiveness to the adherend can be further increased. The range of is more preferable. For the same reason, the wettability is preferably in the range of 2 to 5 seconds.

  As a technical idea of setting the adhesive strength and wettability within the above ranges, for example, as the polyol (a1), an amorphous polycarbonate polyol is used in the polycarbonate polyol (a1-1); In the production of the urethane resin (A) having, the ratio [NCO / OH] of the number of moles of the hydroxyl group possessed by the polyol (a1) and the number of moles of the isocyanate group possessed by the polyisocyanate (a2) is 0.6-0. Reaction in the range of 9; ratio of the number of moles of the hydroxyl group of the urethane resin (A) having a hydroxyl group to the number of moles of the isocyanate group when a polyisocyanate crosslinking agent is used as the crosslinking agent (B). Mixing in a range where [NCO / OH] is 0.1 to 0.5 can be mentioned. The term “amorphous” in the amorphous polycarbonate polyol indicates that the peak of crystallization heat or heat of fusion cannot be confirmed in DSC (differential scanning calorimeter) measurement based on JISK7121: 2012.

  The urethane resin (A) is cross-linked with a cross-linking agent (B) described later, and has a hydroxyl group for obtaining excellent adhesion and wettability, preferably 2 or more, more preferably 2 to 4 It has the hydroxyl group of the range.

  As the urethane resin (A), for example, a reaction product of polyol (a1) and polyisocyanate (a2) can be used.

  Examples of the polyol (a1) include polycarbonate polyol (a1-1), polyether polyol (a1-2), polyester polyol, polybutadiene polyol, polycaprolactone polyol, acrylic polyol, dimer diol, polyisoprene polyol, and the like. Can do. These polyols may be used alone or in combination of two or more. Among these, it is selected from the group consisting of a polycarbonate polyol (a1-1), a polyether polyol (a1-2), and a polyester polyol from the viewpoint that even better oleic acid resistance, gel fraction, and holding power can be obtained. It is preferable to use one or more polyols, and the polycarbonate polyol (a1-1) or the polyether polyol (a1-) can be further improved in the balance between adhesive strength and adhesiveness to the adherend. It is preferable to use 2).

  As said polycarbonate polyol (a1-1), what was obtained by making carbonate ester and / or phosgene react with the compound which has a 2 or more hydroxyl group by a well-known method can be used, for example.

  As the carbonate ester, for example, methyl carbonate, dimethyl carbonate, diethyl carbonate, cyclocarbonate, diphenyl carbonate and the like can be used. These compounds may be used alone or in combination of two or more.

  Examples of the compound having two or more hydroxyl groups include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, dipropylene glycol, 1,4-butanediol, 1, 3-butanediol, 1,5-pentanediol, 1,5-hexanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10 -Decanediol, 3-methyl-1,5-pentanediol, 2-butyl-2-ethylpropanoldiol, neopentyl glycol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol and the like can be used. These compounds may be used alone or in combination of two or more. Among these, the obtained polycarbonate polyol can be made into a liquid and the glass transition temperature of the urethane resin (A) can be lowered, so that excellent adhesive strength (particularly, initial adhesive strength) can be obtained. 1,5-pentanediol and 1,6-hexanediol, 3-methyl-1,5-pentanediol, 2-methyl-1,8- from the point that the balance of sticking property to the body can be further enhanced. One or more compounds selected from the group consisting of octanediol and 1,9-nonanediol are preferably used as raw materials.

  Examples of the polyether polyol (a1-2) include polyoxyethylene polyol, polyoxypropylene polyol, polyoxytetramethylene polyol, polyoxyethylene polyoxypropylene polyol, polyoxyethylene polyoxytetramethylene polyol, and the like. Can do. These polyether polyols may be used alone or in combination of two or more.

  The number average molecular weight of the polyol (a1) is preferably in the range of 500 to 5,000 from the viewpoint of further improving the balance of adhesive strength and adhesiveness to the adherend, A range of 3,000 is preferred. In addition, the number average molecular weight of the said polyol (a1) shows the value measured on condition of the following by the gel permeation chromatography (GPC) method.

Measuring device: High-speed GPC device (“HLC-8220GPC” manufactured by Tosoh Corporation)
Column: The following columns manufactured by Tosoh Corporation were connected in series.
"TSKgel G5000" (7.8 mm ID x 30 cm) x 1 "TSKgel G4000" (7.8 mm ID x 30 cm) x 1 "TSKgel G3000" (7.8 mm ID x 30 cm) x 1 “TSKgel G2000” (7.8 mm ID × 30 cm) × 1 detector: RI (differential refractometer)
Column temperature: 40 ° C
Eluent: Tetrahydrofuran (THF)
Flow rate: 1.0 mL / min Injection amount: 100 μL (tetrahydrofuran solution with a sample concentration of 0.4 mass%)
Standard sample: A calibration curve was prepared using the following standard polystyrene.

(Standard polystyrene)
"TSKgel standard polystyrene A-500" manufactured by Tosoh Corporation
"TSKgel standard polystyrene A-1000" manufactured by Tosoh Corporation
"TSKgel standard polystyrene A-2500" manufactured by Tosoh Corporation
"TSKgel standard polystyrene A-5000" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-1" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-2" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-4" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-10" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-20" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-40" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-80" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-128" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-288" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-550" manufactured by Tosoh Corporation

  A chain extender other than the polyol (a1) may be used in combination with the polyol (a1) as necessary.

  The chain extender can be used for adjusting the adhesive strength, and for example, one having a number average molecular weight in the range of 50 to 400 can be used. Specifically, for example, ethylene glycol, diethylene recall, triethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, hexamethylene glycol, saccharose, methylene glycol, Aliphatic polyol compounds such as glycerin and sorbitol; aromatic polyol compounds such as bisphenol A, 4,4′-dihydroxydiphenyl, 4,4′-dihydroxydiphenyl ether, 4,4′-dihydroxydiphenyl sulfone, hydrogenated bisphenol A, hydroquinone Water; ethylenediamine, 1,2-propanediamine, 1,6-hexamethylenediamine, piperazine, 2-methylpiperazine, 2,5-dimethylpiperazine, isophoronediamine, 4,4 ′ Dicyclohexylmethanediamine, 3,3′-dimethyl-4,4′-dicyclohexylmethanediamine, 1,2-cyclohexanediamine, 1,4-cyclohexanediamine, aminoethylethanolamine, hydrazine, diethylenetriamine, triethylenetetramine, isophoronediamine, etc. These amine compounds can be used. When using the chain extender, it is preferable to use an aliphatic polyol compound from the viewpoint of suppressing discoloration over time, and excellent cohesion can be obtained by using a relatively short chain extender as a hard segment. , Since the adhesive force can be further improved, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, and 3-methyl-1, It is more preferable to use one or more chain extenders selected from the group consisting of 5-pentanediol. When the chain extender is used, the amount used is preferably 10 parts by mass or less, and more preferably 5 parts by mass or less with respect to 100 parts by mass of the urethane resin (A).

  Examples of the polyisocyanate (a2) include aromatic polyisocyanates such as xylylene diisocyanate, phenylene diisocyanate, diphenylmethane diisocyanate, toluene diisocyanate, naphthalene diisocyanate, polymethylene polyphenyl polyisocyanate; hexamethylene diisocyanate, lysine diisocyanate, cyclohexane diisocyanate, Aliphatic or alicyclic polyisocyanates such as isophorone diisocyanate, 4,4′-dicyclohexylmethane diisocyanate, diisocyanate methylcyclohexane, and tetramethylxylylene diisocyanate can be used. These polyisocyanates may be used alone or in combination of two or more.

  As said urethane resin (A), the polyol (a1) and polyisocyanate containing polycarbonate polyol (a1-1) from the point which can improve the balance of adhesive force and the sticking property to a to-be-adhered body further. It is preferable to use the reaction product (a2).

  As the urethane resin (A), as a method for producing the urethane resin (A) in the case of using a reaction product of the polyol (a1) and the polyisocyanate (a2), for example, the moles of isocyanate groups possessed by the polyisocyanate (a2) In the case of using the polyol (a1) and the chain extender with respect to the ratio, there is a method of reacting so that the total molar ratio of the hydroxyl group and amino group becomes excessive. In addition, you may perform the said reaction in the organic solvent (C) mentioned later. The polyol (a1) and the chain extender may be charged all at once or may be charged in two or more times while controlling the reaction. As the molar ratio (NCO / OH + NH) of the total of the polyol (a1) and the hydroxyl group and amino group of the chain extender and the isocyanate group of the polyisocyanate (a2), the reaction can be easily controlled, From the point that a good initial adhesive force is obtained by the cross-linking property with the cross-linking agent (B) described later, the range is preferably 0.3 to 0.99, and more preferably 0.6 to 0.9. . Further, after the production of the urethane resin (A), an alcohol solvent such as methanol or 1,3-butanediol may be added for the purpose of deactivating the remaining isocyanate group.

  The weight average molecular weight of the urethane resin (A) obtained by the above method is 5,000 to 100,000 from the viewpoint of further improving the balance of adhesive strength and adhesiveness to the adherend. Is preferable, and the range of 5,000 to 70,000 is more preferable.

  In addition, the number average molecular weight of the urethane resin (A) is in the range of 3,000 to 50,000 from the viewpoint of further improving the balance of adhesive strength and adhesiveness to the adherend. It is preferable that it is in the range of 4,000 to 30,000, more preferably in the range of 4,000 to 20,000. In addition, the weight average molecular weight and number average molecular weight of the said urethane resin (A) show the value obtained by measuring similarly to the number average molecular weight of the said polyol (a1).

  As said crosslinking agent (B), a polyisocyanate crosslinking agent, a melamine crosslinking agent, etc. can be used, for example. These crosslinking agents may be used alone or in combination of two or more. Among these, it is preferable to use a polyisocyanate crosslinking agent from the viewpoint of showing good crosslinking with the urethane resin (A) and obtaining excellent adhesive force.

  Examples of the polyisocyanate crosslinking agent include polyisocyanates such as tolylene diisocyanate, chlorophenylene diisocyanate, hexamethylene diisocyanate, tetramethylene diisocyanate, xylylene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate; and these trimethylolpropanes. These isocyanurates, these burettes, these adducts, polymethylene polyphenyl polyisocyanate, and the like can be used. These crosslinking agents may be used alone or in combination of two or more.

  As the content of the crosslinking agent (B), the urethane resin (A) and the good crosslinking are formed, and from the point that the adhesive force, and the balance of the adherence to the adherend can be further enhanced, The range is preferably 0.1 to 4 parts by mass, more preferably 0.2 to 3 parts by mass with respect to 100 parts by mass of the solid content of the urethane resin (A).

  Examples of the organic solvent (C) include ester solvents such as ethyl acetate, methyl acetate, and butyl acetate; ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; and aliphatic hydrocarbons such as heptane, hexane, cyclohexane, and methylcyclohexane. Solvent: Aromatic hydrocarbon solvents such as toluene, o-xylene, m-xylene and p-xylene can be used. These organic solvents may be used alone or in combination of two or more.

  As content of the said organic solvent (C), it is preferable that it is the range of 20-80 mass% in an adhesive composition from the point of coating property and drying property, and the range of 30-70 mass% is more preferable. .

  The pressure-sensitive adhesive composition of the present invention contains the components (A) to (C) as essential components, but may further contain other additives as necessary.

  Examples of the other additives include a rust inhibitor, an antioxidant, an antistatic agent, a thixotropic agent, a dispersant, a sensitizer, a urethanization catalyst, a polymerization inhibitor, a leveling agent, a tackifier, and a foam stabilizer. An agent or the like can be used. These additives may be used alone or in combination of two or more.

  As a method for producing the pressure-sensitive adhesive sheet of the present invention, for example, by applying the pressure-sensitive adhesive composition to a substrate and drying, the substrate and a cured film (= pressure-sensitive adhesive layer) of the pressure-sensitive adhesive composition are obtained. The method of manufacturing the adhesive sheet which has is mentioned.

  As the substrate, for example, a sheet obtained by using polyester such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polyolefin, polyacrylate, polyvinyl chloride, polyethylene, polypropylene ethylene vinyl alcohol, polyurethane, polyamide, polyimide, etc. Or a film; glass etc. can be used. The surface of these base materials may be subjected to mold release treatment, antistatic treatment, corona treatment and the like. The thickness of the base material is determined according to the use for which the pressure-sensitive adhesive sheet is used, and is, for example, in the range of 10 to 100 μm.

  Examples of the method for applying the pressure-sensitive adhesive composition to the substrate include a method using an applicator, a roll coater, a gravure coater, a reverse coater, a spray coater, an air knife coater, a die coater and the like.

  The thickness of the coated adhesive composition after drying is determined according to the application in which the adhesive sheet is used, and is, for example, in the range of 5 to 100 μm.

  Examples of a method for drying the pressure-sensitive adhesive composition after coating the pressure-sensitive adhesive composition on the substrate include a method of drying at 50 to 140 ° C. for 30 seconds to 10 minutes. Moreover, you may perform aging in the range of 30 to 50 degreeC after the said drying from the point which accelerates | stimulates a crosslinking reaction.

  The gel fraction when the dried film is immersed in toluene for 24 hours is preferably in the range of 10 to 60% by mass from the viewpoint of further improving the adhesive strength, particularly the initial adhesive strength. A range of 55% by weight is more preferred.

  The initial adhesive strength of the pressure-sensitive adhesive sheet is preferably in the range of 1 to 20 N / 25 mm, more preferably in the range of 5 to 20 N / 25 mm. In addition, the measuring method of the initial adhesive force of the said adhesive sheet is described in the Example mentioned later.

  As described above, the pressure-sensitive adhesive sheet obtained from the pressure-sensitive adhesive composition of the present invention has excellent adhesive strength and adhesiveness to an adherend, and has excellent wettability without involving air in the adherend. Can be attached to the adherend.

  Examples of the adherend of the pressure-sensitive adhesive sheet of the present invention include glass, polypropylene, polyacryl, and polycarbonate.

  Hereinafter, the present invention will be described in more detail with reference to examples.

[Synthesis Example 1]
<Synthesis of Urethane Resin (A-1)>
In a reaction vessel equipped with a stirrer, a reflux condenser, a nitrogen inlet tube, and a thermometer, 1,5-pentanediol and 1,6-hexanediol-based polycarbonate polyol (“Duranol T5652” manufactured by Asahi Kasei Chemicals Corporation, number average molecular weight; 2,000 (hereinafter abbreviated as “PC-1”) 700 parts by mass, ethylene glycol (hereinafter abbreviated as “EG”) 9 parts by mass, 4,4′-diphenylmethane diisocyanate (hereinafter “MDI”) 95 parts by mass, polymethylene polyphenyl polyisocyanate “Millionate MR-200” (hereinafter abbreviated as “MR-200”) manufactured by Tosoh Corporation, 6 parts by mass, triphenyl phosphite 1 810 parts by mass of N, N-dimethylformamide (hereinafter abbreviated as “DMF”), It warmed to 0 ℃ and reacted. Thereafter, 1 part by mass of 1,3-butanediol was added, heated at 70 ° C. for 1 hour, and cooled to obtain a urethane resin (A-1) having a solid content of 50% by mass and a weight average molecular weight of 29,500. )

[Synthesis Example 2]
<Synthesis of Urethane Resin (A-2)>
A reaction vessel equipped with a stirrer, a reflux condenser, a nitrogen inlet tube, and a thermometer was charged with 1000 parts by weight of PC-1, 86 parts by weight of MDI and 724 parts by weight of ethyl acetate, and heated to 75 ° C. for reaction. Then, it was cooled to 70 degrees. Thereafter, 1 part by mass of 1,3-butanediol was added, heated at 70 ° C. for 1 hour, and cooled to obtain a urethane resin having a solid content of 60% by mass and a weight average molecular weight of 18,900 (A-2 )

[Synthesis Example 3]
<Synthesis of Urethane Resin (A-3)>
In a reaction vessel equipped with a stirrer, a reflux condenser, a nitrogen inlet tube, and a thermometer, 1,6-hexanediol-based polycarbonate polyol (“PH300D” manufactured by Ube Industries, Ltd., hereinafter abbreviated as “PC-2”) is used. 1470 parts by mass, 70 parts by mass of MDI, and 1030 parts by mass of ethyl acetate were added and reacted by heating to 75 ° C., and then cooled to 70 degrees. Thereafter, 1 part by mass of 1,3-butanediol was added, and the mixture was heated at 70 ° C. for 1 hour and cooled to obtain a urethane resin having a solid content of 60% by mass and a weight average molecular weight of 17,200 (A-3 )

[Synthesis Example 4]
<Synthesis of Urethane Resin (A-4)>
In a reaction vessel equipped with a stirrer, reflux condenser, nitrogen inlet tube, and thermometer, 1,9-nonanediol and 1,6-octanediol-based polycarbonate polyol (“C-2015N” manufactured by Kuraray Co., Ltd., hereinafter “PC-” 3 ”)), 990 parts by mass, 85 parts by mass of MDI, and 1790 parts by mass of ethyl acetate were added and heated to 75 ° C. for reaction, and then cooled to 70 ° C. Thereafter, 1 part by mass of 1,3-butanediol was added, heated at 70 ° C. for 1 hour, and cooled to obtain a solid content of 60% by mass and a weight average molecular weight of 20,800 urethane resin (A-4). Got.

[Synthesis Example 5]
<Synthesis of urethane resin (A-5)>
In a reaction vessel equipped with a stirrer, a reflux condenser, a nitrogen inlet tube, and a thermometer, 900 parts by mass of PC-1 and 20 parts by mass of polyethylene glycol (number average molecular weight: 400, hereinafter abbreviated as “PEG”), 90 parts by mass of MDI and 670 parts by mass of ethyl acetate were charged, heated to 75 ° C. for reaction, and then cooled to 70 ° C. Thereafter, 1 part by mass of 1,3-butanediol was added, heated at 70 ° C. for 1 hour, and cooled to obtain a urethane resin (A-5 having a solid content of 60% by mass and a weight average molecular weight of 20,000). )

[Synthesis Example 7]
<Synthesis of acrylic resin (AR-1)>
Into a reaction vessel equipped with a stirrer, a reflux condenser, a nitrogen introduction tube, and a thermometer, 675 parts by mass of 2-ethylhexyl acrylate, 1675 parts by mass of n-butyl acrylate, and 52 parts by mass of acrylic acid were charged, and nitrogen was blown into the reactor while stirring The temperature was raised to 70 ° C. After 1 hour, 20 parts by mass of an azobisisobutyronitrile solution (solid content: 3.5% by mass) previously dissolved in ethyl acetate was added. Then, after holding for 8 hours at 70 ° C. with stirring, the contents were cooled and filtered through a 200 mesh wire net, and an acrylic resin (AR) having a nonvolatile content of 55% by mass, a viscosity of 5,000 mPa · s, and a weight average molecular weight of 400,000 -1) was obtained.

[Example 1]
0.7 parts by mass of MR-200 was added to 100 parts by mass of the urethane resin (A-1) obtained in Synthesis Example 1 to obtain an adhesive composition.

[Measurement method of adhesive strength]
On the surface of a polyethylene terephthalate (PET) film having been subjected to a mold release treatment with a thickness of 25 μm, the pressure-sensitive adhesive composition immediately after blending the crosslinking agent was applied so that the film thickness after drying was 25 μm, Dry at 80 ° C. for 3 minutes. A release-treated PET film having a thickness of 38 μm was bonded thereto, and left at 40 ° C. for 3 days to obtain an adhesive sheet.
One of the release sheets of the obtained pressure-sensitive adhesive sheet was peeled off and cut into a width of 25 mm to obtain a test piece. The release PET of the test piece was peeled off, bonded to a stainless steel (SUS) plate so that the adhesion area was 25 mm × 60 mm, and 2 kg roll × 2 reciprocating pressure bonded. Then, after being left for 24 hours in an atmosphere of 23 ° C. and a humidity of 50%, a 180 ° peel strength was measured in an atmosphere of 23 ° C. and a humidity of 50% according to JIS K6848-1974, and the adhesive strength (N / 25 mm) It was.

[Evaluation method for bonding properties]
The pressure-sensitive adhesive composition immediately after the crosslinking agent was blended was applied on the surface of a polyethylene terephthalate (PET) film having a thickness of 50 μm so that the film thickness after drying was 10 μm, and dried at 80 ° C. for 3 minutes. . A release-treated PET film having a thickness of 38 μm was bonded thereto, and left at 40 ° C. for 3 days to obtain an adhesive sheet.
This pressure-sensitive adhesive sheet was cut into a 5 cm × 15 cm rectangle, the release PET film was peeled off, and both ends of the long side were held by hand and curved. The center part of the exposed pressure-sensitive adhesive layer was brought into contact with the glass plate, and then released, and the time (seconds) until the whole pressure-sensitive adhesive layer was adhered to the glass plate by its own weight was measured. In addition to the glass plate, the same evaluation is made with an acrylic resin plate (hereinafter abbreviated as “PMMA”), a polypropylene plate (hereinafter abbreviated as “PP”), and a polycarbonate plate (hereinafter abbreviated as “PC”). )).

[Examples 2 to 10, Comparative Example 1]
A pressure-sensitive adhesive composition was obtained in the same manner as in Example 1 except that the type of urethane resin (A) used and the type and amount of the crosslinking agent (B) were changed as shown in Tables 1 and 2, and a pressure-sensitive adhesive sheet was obtained. The physical properties of were measured.

Abbreviations in Tables 1 and 2 are as follows.
"D-40"; adduct of toluene diisocyanate "D-75HE"; adduct of 1,6-hexane diisocyanate "D-100K"; 1,6-hexane diisocyanate nurate "D101"; 1,6-hexane Bifunctional diisocyanate

  It was found that the pressure-sensitive adhesive sheet obtained from the pressure-sensitive adhesive composition of the present invention was excellent in adhesive strength and adhesiveness to an adherend.

  On the other hand, although the comparative example 1 is the aspect using an acrylic resin, the sticking property to a to-be-adhered body was unsatisfactory.

Claims (4)

A pressure-sensitive adhesive composition containing a urethane resin (A) having a hydroxyl group, a crosslinking agent (B), and an organic solvent (C),
The adhesive strength of the pressure-sensitive adhesive sheet having the cured film is 1 N / 25 mm or more, and
Holding the both ends of the long side of the 50 mm x 150 mm pressure-sensitive adhesive sheet by hand, bringing the center of the pressure-sensitive adhesive sheet into contact with the adherend, releasing the hand, and the time until the entire pressure-sensitive adhesive sheet is adhered to the adherend A pressure-sensitive adhesive composition characterized by being 10 seconds or shorter. The pressure-sensitive adhesive composition according to claim 1, wherein the urethane resin (A) having a hydroxyl group is a reaction product of a polyol (a1) containing a polycarbonate polyol (a1-1) and a polyisocyanate (a2). The pressure-sensitive adhesive composition according to claim 1 or 2, wherein the crosslinking agent (B) is a polyisocyanate crosslinking agent. It has a cured film of the adhesive composition of any one of Claims 1-3, The adhesive sheet characterized by the above-mentioned.