JP2016204466A - Urethane prepolymer and two-liquid type urethane adhesive using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a urethane prepolymer with no poor appearance that facilitates good handling and has moderate curability, and to provide a two-liquid curable type urethane adhesive using the urethane prepolymer.SOLUTION: The urethane prepolymer is produced by using a polyether diol A, a polyether polyol B and a polyisocyanate C. In the urethane prepolymer, the polyether diol A has a degree of unsaturation of 0.07 meq/g or less and a number average molecular weight in the range of 3,000 to 30,000; the polyether polyol B is a trifunctional or more polyether polyol and has a degree of unsaturation of 0.07 meq/g or less and a number average molecular weight in the range of 5,000 to 40,000; the ratio of NCO groups which the polyisocyanate C has to the total amount of OH groups which the polyether diol A and the polyether polyol B have is in the range of 0.85 to 1.15 (molar ratio); and the upper limit of an average functional group number fof a polyether polyol mixture as a combination of the polyether diol A and the polyether polyol B is 2.20. The urethane prepolymer having such characteristics is used in a two-liquid curable type urethane adhesive.SELECTED DRAWING: None

Description

  The present invention relates to a urethane prepolymer and a two-component urethane adhesive using the same.

  Adhesives are used in, for example, tapes, labels, seals, cosmetic sheets, non-slip sheets, double-sided adhesive tapes, etc. In recent years, various adhesives such as adhesion of liquid crystal displays and touch panels of personal computers, televisions, mobile phones, etc. Used in the field.

  As the adhesive, for example, an acrylic adhesive, a rubber adhesive, a silicone adhesive, a urethane adhesive, an oxyalkylene adhesive, and the like are known, and particularly recently, a strong adhesive having a strong adhesive force. There is a tendency that acrylic pressure-sensitive adhesives are used in a wide range of applications from mold-type pressure-sensitive adhesives to slightly pressure-sensitive pressure-sensitive adhesives having minute adhesive strength.

  However, the acrylic pressure-sensitive adhesive has problems with odor and skin irritation when the acrylic monomer remains in the pressure-sensitive adhesive. In addition, the acrylic pressure-sensitive adhesive tends to increase in adhesive strength or transferability due to a change with time after being attached to an adherend. For this reason, there is a problem that adhesive residue tends to be generated on the adherend and re-peelability tends to be insufficient. In addition, the acrylic pressure-sensitive adhesive has a problem that it has poor impact resistance at low temperatures due to the use of a comonomer having a high glass transition temperature in order to develop cohesive force, resulting in poor low-temperature characteristics.

  In contrast, urethane-based adhesives have the advantage of having a smaller molecular weight than acrylic adhesives and can easily follow changes in the shape of the adherend, but it is difficult to increase the molecular weight. By containing, cohesive force is secured. In the case of such a pressure-sensitive adhesive with a large addition amount of the curing agent, it is said that the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet has a high elastic modulus and is difficult to increase the adhesive force.

  For example, Patent Document 1 discloses a polyether polyol having an average number of functional groups per molecule of 2.2 to 3.4, a polyisocyanate compound, a catalyst, and a pressure-sensitive adhesive having low release rate dependency and good transparency. OH-terminated urethane prepolymer A containing a polyfunctional isocyanate compound B and an OH group of component A and an NCO group of component B in an NCO / OH equivalent ratio in the range of 0.5 to 1.6 An adhesive composition is disclosed.

  However, the polyurethane pressure-sensitive adhesive composition described in Patent Document 1 has a low molecular weight of polyether polyol and uses a large amount of trifunctional polyether polyol. There was a problem that bubbles could not be generated and a problem that thixotropy was developed and handling property at the time of coating was poor. Moreover, since adhesive force was low, it was inferior to the adhesiveness to a base material. Furthermore, since the molecular weight of the polyol used is low and the amount of isocyanate used is relatively large, many hard domains having crystallinity may be formed. When used in optical applications, the transparency is not sufficient, and There was concern that poor solubility and poor appearance due to undissolved components occurred.

JP 2006-18295 A

  The present invention has been made in view of the above-mentioned background art, and the object thereof is a urethane prepolymer that has no poor appearance, can be handled well, and has an appropriate curability, and a two-component curable urethane using the same. It is to provide an adhesive.

  As a result of intensive studies to solve the above problems, the present inventors have determined that a specific blending ratio of a specific degree of unsaturation, a polyether diol having a molecular weight and a specific degree of unsaturation, a polyether polyol having a molecular weight, and a polyisocyanate. It was found that the above-mentioned problems can be solved by blending in, and the present invention has been completed.

  That is, the present invention relates to a urethane prepolymer and a two-component curable urethane pressure-sensitive adhesive using the same as shown below.

[1] A urethane prepolymer obtained by using polyether diol A, polyether polyol B, and polyisocyanate C,
The degree of unsaturation of the polyether diol A is 0.07 meq / g or less, and the number average molecular weight is in the range of 3000 to 30000,
The polyether polyol B is a tri- or higher functional polyether polyol, the degree of unsaturation is 0.07 meq / g or less, and the number average molecular weight is in the range of 5000 to 40000,
The ratio of the NCO group of the polyisocyanate C to the total amount of OH groups of the polyether diol A and the polyether polyol B is in the range of 0.85 to 1.15 (molar ratio); and the polyether diol A urethane prepolymer, wherein the upper limit of the average functional group number f _ave as a polyether polyol mixture of A and polyether polyol B is 2.20.

[2] The degree of unsaturation (meq / g) and the number average molecular weight of the polyether diol A are as follows:
Unsaturation ≦ Number average molecular weight × 0.00001
The urethane prepolymer as described in [1] above, wherein

  [3] The urethane prepolymer as described in [1] or [2] above, wherein the polyisocyanate C is at least one selected from the group consisting of aliphatic isocyanates, alicyclic isocyanates, and modified products thereof. .

  [4] The urethane prepolymer according to any one of the above [1] to [3], wherein the number average molecular weight (Mn) in terms of standard polystyrene is in the range of 30,000 to 300,000.

  [5] Any of the above [1] to [4], wherein the polyether diol A is obtained by ring-opening polymerization of alkylene oxide using an imino group-containing phosphazenium salt catalyst The urethane prepolymer according to any one of the above.

  [6] A urethane prepolymer solution obtained by using the urethane prepolymer according to any one of [1] to [5] above and a solvent, wherein the concentration of the urethane prepolymer is in the range of 10 to 90% by weight. .

  [7] A cured product obtained by using the urethane prepolymer according to any one of [1] to [5] above and a crosslinking agent D having reactivity with an active hydrogen group or an isocyanate group. A two-component curable polyurethane.

  [8] The two-component curable type according to [7], wherein the crosslinking agent D is used in a range of 0.0001 equivalent to 20 equivalents (molar ratio) with respect to the reactive group of the urethane prepolymer. Polyurethane.

  [9] A urethane pressure-sensitive adhesive containing the urethane prepolymer according to any one of [1] to [5].

  [10] A two-component curable urethane pressure-sensitive adhesive obtained using the two-component curable polyurethane described in [7] or [8].

  [11] An optical pressure-sensitive adhesive sheet obtained by using the urethane pressure-sensitive adhesive according to [9] or [10].

  The urethane prepolymer of the present invention has no poor appearance, can be handled well, and has an appropriate curability.

  Moreover, since the two-component curable polyurethane of the present invention has high flexibility and low temperature characteristics and can exhibit transparency and adhesiveness, it can be suitably used as a two-component curable urethane pressure-sensitive adhesive. .

  Hereinafter, the present invention will be described in detail.

The present invention is a urethane prepolymer obtained using polyether diol A, tri- or higher functional polyether polyol B, and polyisocyanate C,
The degree of unsaturation of the polyether diol A is 0.07 meq / g or less, and the number average molecular weight is in the range of 3000 to 30000,
The degree of unsaturation of the polyether polyol B is 0.07 meq / g or less and the number average molecular weight is in the range of 5000 to 40000,
The ratio of the NCO group of the polyisocyanate C to the total amount of OH groups of the polyether diol A and the polyether polyol B is in the range of 0.85 to 1.15 (molar ratio); and the polyether diol The upper limit of the average functional group number f _ave as a polyether polyol mixture of A and polyether polyol B is 2.20.

<Polyetherdiol A>
The polyether diol A used in the urethane prepolymer of the present invention is preferably a compound having an oxyalkylene group and having two hydroxyl groups per molecule in any molecule such as a polymer terminal or a branched terminal. .

  Examples of such polyether diol A include bifunctional polyalkylene oxides such as polyoxypropylene glycol, polyoxyethylene glycol, and poly (oxypropylene-oxyethylene) diol, and are not particularly limited. However, specifically, Sannix PP-1000, PP-2000, PP-3000, PP-4000 manufactured by Sanyo Chemical Co., Ltd. Actol P-22, P-21, P-23, P-28 manufactured by Mitsui Chemicals, Inc. , ED-28, manufactured by Asahi Glass Co., Ltd. , NOF Obtained as commercial products such as Uniol D-1000, D-1200, D-2000, D-4000, PB-700, PEG # 1500, PEG # 2000, Pronon # 102, # 104, # 202B, # 204, etc. Can do.

  The polyether diol A is not limited to one type, and a plurality of types of polyether diols may be mixed and used.

  The polyether diol A preferably has an oxypropylene group and may have an oxyethylene group.

  The number average molecular weight (Mn) of the polyether diol A is in the range of 3000 to 30000. More preferably, it is the range of 3500-20000, Most preferably, it is the range of 4000-15000. If the number average molecular weight of the polyether diol A is less than 3000, curing proceeds too early, the pot life is short and molding is difficult, and the resulting cured product is also inflexible, so the flexibility is sufficient for applications with large step portions. However, since bubbles are generated without following the steps, it is difficult to use. Also, if the number average molecular weight of polyether diol A exceeds 30000, the cohesive force is insufficient and the curability is not sufficient and difficult to use, and the urethane prepolymer is synthesized industrially due to a decrease in reactivity and an increase in viscosity. It is also difficult to do.

In the present invention, the “number average molecular weight” of the polyether diol A is based on the hydroxyl value (OHV, unit is mg KOH / g) of the polyether diol A and is represented by the following formula:
Number average molecular weight = (56100 / OHV) × A value calculated using the number of hydroxyl groups per molecule.

  Here, “OHV” is a value measured according to JIS K1557 6.4. The “number of hydroxyl groups per molecule” refers to the number of active hydrogen atoms per molecule of the initiator used as a raw material when producing polyether diol A. For example, ethylene glycol and propylene glycol are 2 Yes, glycerin and trimethylolpropane are 3. If the number of active hydrogen atoms in the initiator cannot be specified in a commercial product, the nominal functional group number is used.

  The molecular weight distribution of the polyether diol A is not particularly limited, but is preferably less than 1.16, more preferably less than 1.13, and particularly preferably less than 1.10. By making molecular weight distribution less than 1.16, the viscosity reduction of the prepolymer obtained and the reactivity improvement of prepolymerization can be anticipated.

  In the present invention, the molecular weight distribution (Mw / Mn) of the polyether diol A is a polystyrene obtained by measuring with gel permeation chromatography (GPC) using a calibration curve prepared using a standard polystyrene sample with a known molecular weight. The molecular weight distribution in terms of conversion, which is a value obtained by dividing the GPC mass average molecular weight (Mw) by the GPC number average molecular weight (Mn). The molecular weight distribution by the GPC method can be determined, for example, in terms of polystyrene by measuring at 40 ° C. using tetrahydrofuran as a solvent.

  The degree of unsaturation of the polyether diol A is 0.07 meq / g or less. Preferably it is the range of 0.01-0.07 meq / g, More preferably, it is the range of 0.014-0.06 meq / g. When the degree of unsaturation of the polyether diol A exceeds 0.07 meq / g, the urethane prepolymer obtained does not show good curability and becomes a cured product in which a large number of migration components are generated, making it difficult to use.

  When two or more kinds of polyether diols are used in combination to obtain polyether diol A, the degree of unsaturation of each polyether diol is preferably 0.07 meq / g or less, but the degree of unsaturation is 0.07 meq / g. When using a polyether diol of g or more, it may be mixed with other polyether diols so that the average total unsaturation of the mixture is 0.07 meq / g or less.

The degree of unsaturation of the polyether diol A is an indicator of the amount of monool present in the polyether diol A, and the average functional group number f _A may decrease with an increase. In the present invention, however, Polyether diol A ".

  In the present invention, the “unsaturation degree (meq / g)” of the polyether diol A is the total amount of unsaturated groups contained in 1 g of the polyether diol A, and is defined in JIS K1557 6.7. It is a value measured according to the method.

The degree of unsaturation (meq / g) and number average molecular weight of the polyether diol A used in the urethane prepolymer of the present invention are as follows:
Unsaturation ≦ Number average molecular weight × 0.00001
It is preferable to satisfy. Above all, the following formula:
Number average molecular weight × 0.0000025 ≦ Unsaturation ≦ Number average molecular weight × 0.000009
Preferably satisfying the following formula:
Number average molecular weight × 0.000003 ≦ Unsaturation ≦ Number average molecular weight × 0.000008
It is further preferable to satisfy It is preferable to make the degree of unsaturation of the polyether diol A not more than the number average molecular weight × 0.00001 because a cured product of the obtained urethane prepolymer can be expected to have good flexibility.

  There is no restriction | limiting in particular as a manufacturing method of polyetherdiol A, It can manufacture with a conventionally well-known manufacturing method. For example, it can be produced by ring-opening polymerization of alkylene oxide in the presence of a ring-opening polymerization catalyst using a bifunctional initiator.

  The ring-opening polymerization catalyst is not particularly limited. For example, a general-purpose alkali metal compound catalyst such as potassium hydroxide (KOH) or sodium hydroxide; a cesium metal compound catalyst such as cesium hydroxide; a composite such as zinc hexacyanocobaltate complex Metal cyanide complex catalyst; phosphazene catalyst, imino group-containing phosphazenium salt catalyst, barium hydroxide catalyst and the like. These catalysts may be used alone or in combination of two or more.

  Among these catalysts, in order to produce polyether diol A having a low degree of unsaturation, a cesium metal compound catalyst, a double metal cyanide complex catalyst, a phosphazene catalyst, an imino group-containing phosphazenium salt catalyst, barium hydroxide It is preferable to use a catalyst or the like. Moreover, since the molecular weight distribution of the obtained polyether diol A becomes narrow by producing the polyether diol A using the imino group-containing phosphazenium salt catalyst, the polyether diol A and the prepolymer using the same It is preferable because a decrease in viscosity and a reduction in migration components when cured can be expected.

  The imino group-containing phosphazenium salt catalyst is not particularly limited as long as it is a compound having an imino group and a PN bond, and examples thereof include compounds represented by the following general formula (for example, JP-A-2011-132179). No. publication).

[In said general formula, R < ₁ > and R < ₂ > respectively independently represents a hydrogen atom or a C1-C20 hydrocarbon group. R ₁ and R ₂ may be bonded to each other to form a ring structure, or R ₁ or R ₂ may be bonded to each other to form a ring structure. X ⁻ represents a hydroxy anion, an alkoxy anion having 1 to 4 carbon atoms, a carboxy anion, an alkyl carboxy anion having 2 to 5 carbon atoms, or a hydrogen carbonate anion. ]
Although it does not specifically limit as a bifunctional initiator, For example, bifunctional polyols, such as water, propylene glycol, ethylene glycol, diethylene glycol, dipropylene glycol, butylene glycol, 1, 6-hexanediol, polyoxyalkylene diol, Selected from bisphenols such as bisphenol A, bisphenol F, and bisphenol AD, dihydroxybenzenes such as catechol, resorcin, and hydroquinone, and compounds having two active hydrogens such as amines such as methylamine, ethylamine, propylamine, and butylamine One type or two or more types are used.

  Although it does not specifically limit as alkylene oxide, For example, 1 type, or 2 or more types chosen from the group which consists of ethylene oxide, propylene oxide, and butylene oxide is used.

  Among these, polyether diols obtained by using one or two or more of the above-mentioned bifunctional initiators and ring-opening polymerization of one or more of three-membered alkylene oxides having 2 to 3 carbon atoms are preferable.

  As a method for producing polyether diol A, specifically, a cesium metal compound catalyst, a double metal cyanide complex catalyst, a phosphazene catalyst, an imino group-containing phosphazenium salt catalyst, a barium hydroxide catalyst, and the like are used. A method of adding alkylene oxide to a predetermined molecular weight with a bifunctional initiator, potassium hydroxide catalyst, cesium metal compound catalyst, double metal cyanide complex catalyst, phosphazene catalyst, imino group-containing phosphazenium salt catalyst, water Using a barium oxide catalyst or the like, an alkylene oxide is added to a number average molecular weight of about 200 to 10,000, and then the cesium metal compound catalyst, double metal cyanide complex catalyst, phosphazene catalyst, imino group is contained in the state where the catalyst is removed or remains. Phosphazenium salt catalyst, barium hydroxide catalyst, etc. And a method of adding an alkylene oxide with 2 or more stages until a predetermined molecular weight is illustrated using species or two or more.

<Polyether polyol B>
As the polyether polyol B used in the present invention, a polyether polyol having an oxyalkylene group and having at least three hydroxyl groups per molecule in any molecule such as a polymer terminal and a branched chain terminal is used. preferable.

  Examples of such polyether polyol B include, but are not particularly limited to, polyalkylene oxides having three or more functions such as polyoxypropylene polyol, polyoxyethylene polyol, and poly (oxypropylene-oxyethylene) polyol. However, Sanix Chemicals Sanix GP-1000, GP-1500, GP-3000, GP-4000V, GA-5000S, FA-908, FA-961, FA-921, FA-703, FA -757, Mitsui Chemicals Actol G-28, MN-5000, MN-4000, P-31, MN-1500, Asahi Glass Co., Ltd. Exenol 1030, 4030, 5030, 230, 828, 837, Preminol 3005, 3010, 3015, 3020, 7001, 70 6,7012, available as PREMINOL S3006,3011, and PREMINOL 7021 (tetrafunctional) commercially available, such as.

  The number of hydroxyl groups per molecule of the polyether polyol B is preferably in the range of 3-6, and more preferably in the range of 3-4. When the number of hydroxyl groups per molecule of the polyether polyol B is in the range of 3 to 6, it is preferable because the cured product of the obtained urethane prepolymer can be expected to have good flexibility and adhesiveness.

  The number of hydroxyl groups per molecule of the polyether polyol B matches the number of active hydrogen atoms of the polyvalent initiator used for producing the polyether polyol B described later. For example, glycerin and trimethylolpropane are 3 and diphenylmethanediamine is 4.

  The number average molecular weight (Mn) of the polyether polyol B is in the range of 5000 to 40000, preferably in the range of 5000 to 30000, and more preferably in the range of 6000 to 20000. If the number average molecular weight of the polyether polyol B is less than 5000, the curing proceeds too early, the pot life is short and the molding is difficult, and the resulting cured product is also inflexible, so the flexibility is sufficient for applications where the level difference is large. However, since bubbles are generated without following the steps, it is difficult to use. Moreover, when the number average molecular weight of polyether polyol B exceeds 40,000, the cohesive force is insufficient and the curability is insufficient and the use is difficult, and a urethane prepolymer is synthesized industrially due to a decrease in reactivity and an increase in viscosity. It is also difficult to do.

In the present invention, the number average molecular weight of the polyether polyol B is represented by the following formula based on the hydroxyl value (OHV, unit is mg KOH / g) of the polyether diol B:
Number average molecular weight = (56100 / OHV) × A value calculated using the number of hydroxyl groups per molecule.

  Here, “OHV” is a value measured according to JIS K1557 6.4. The “number of hydroxyl groups per molecule” means the number of active hydrogen atoms per molecule of the initiator used as a raw material when producing the polyether diol B. If the number of active hydrogen atoms in the initiator cannot be specified with a commercial product, the nominal functional group number is used.

  The molecular weight distribution of the polyether polyol B is not particularly limited, but is preferably less than 1.30, and more preferably less than 1.25. A molecular weight distribution of less than 1.30 is preferred because the resulting urethane prepolymer can be expected to have reduced viscosity and high reactivity.

  In the present invention, the molecular weight distribution (Mw / Mn) of the polyether polyol B can be determined by the same method as the molecular weight distribution of the polyether diol A described above.

  The degree of unsaturation of the polyether polyol B is 0.07 meq / g or less, preferably in the range of 0.003 to 0.07 meq / g, more preferably in the range of 0.004 to 0.06 meq / g. . When the degree of unsaturation exceeds 0.07 meq / g, the resulting urethane prepolymer does not exhibit good curability and is hard to be used because it becomes a cured product in which many migration components are generated.

  When two or more kinds of polyether polyols are used in combination to obtain polyether polyol B, the degree of unsaturation of each polyether polyol is preferably 0.07 meq / g or less, but the degree of unsaturation is 0.07 meq / g. When using a polyether polyol of g or more, it may be mixed with other polyether polyols so that the average total unsaturation degree of the mixture is 0.07 meq / g or less.

By degree of unsaturation increases, there is the average functionality f _B of the polyether polyol B is lowered, but in the present invention include those referred to as "polyether polyol B".

  In the present invention, the “unsaturation degree (meq / g)” of the polyether polyol B is the total amount of unsaturated groups contained in 1 g of the polyether polyol B, and is defined in JIS K1557 6.7. It is a value measured according to the method.

The unsaturation degree and number average molecular weight of the polyether polyol B used in the urethane prepolymer of the present invention are represented by the following formula:
Unsaturation ≦ Number average molecular weight × 0.000009
It is preferable to satisfy the following formula:
Number average molecular weight × 0.0000003 ≦ Unsaturation ≦ Number average molecular weight × 0.000007
It is preferable to satisfy. By setting the degree of unsaturation to a number average molecular weight × 0.000009 or less, the molecular weight of the obtained urethane prepolymer is increased, and an improvement in flexibility can be expected.

  The polyether polyol B is not limited to one type, and a plurality of types of polyether polyols may be mixed and used.

  There is no restriction | limiting in particular as a manufacturing method of polyether polyol B, It can manufacture with a conventionally well-known manufacturing method. For example, it can be produced by ring-opening polymerization of alkylene oxide in the presence of a ring-opening polymerization catalyst using a trifunctional or higher polyvalent initiator.

  As the ring-opening polymerization catalyst, for example, those described above can be used.

  Examples of the tri- or higher functional polyvalent initiator include glycerin, trimethylolpropane, 1,2,6-hexanetriol, Sanyo Chemicals Sanix GP-250, GP-400, GP-600, GP-1000, and the like. A compound having three or more active hydrogens such as triols such as trifunctional low molecular weight polyols, tetraols such as pentaerythritol and diglycerin, hexols, ammonia, ethanolamine, diethanolamine, triethanolamines and other amines Or two or more can be used.

  As the alkylene oxide, for example, those described above can be used.

  Among these, it was obtained by using one or two or more initiators having three or more functional groups and ring-opening polymerizing one or two or more three-membered alkylene oxides having 2 to 3 carbon atoms. Polyoxyalkylene polyol is preferred.

  There is no restriction | limiting in particular as a manufacturing method of polyether polyol B used for the urethane prepolymer of this invention, It can manufacture with a conventionally well-known manufacturing method. For example, a cesium metal compound catalyst, a double metal cyanide complex catalyst, a phosphazene catalyst, an imino group-containing phosphazenium salt catalyst, a barium hydroxide catalyst, etc. are used in one stage or two or more stages for a tri- or higher functional initiator. A method of adding alkylene oxide to a predetermined molecular weight can be mentioned.

<Polyol mixture>
The upper limit of the average functional group number f _{ave in} the polyol mixture of the polyether diol A and the polyether polyol B used in the urethane prepolymer of the present invention is 2.20, preferably 2.19, more preferably 2 .15. When the average functional group number f _ave of the polyol mixture of polyether diol A and polyether polyol B exceeds 2.20, the gelation and curing of the urethane prepolymer progresses too early, and the pot life is short and difficult to mold. Since the obtained cured product is also not flexible, it is difficult to use in applications where the step portion is large because the flexibility is not sufficient and bubbles cannot be generated following the step.

Further, the lower limit of the average functional group number f _ave as a polyol mixture of polyether diol A and polyether polyol B used in the urethane prepolymer of the present invention is not particularly limited, but 1.70 is preferable, 1.75 is more preferable, and 1.80 is particularly preferable. If the average functional group number f _ave of the polyol mixture of the polyether diol A and the polyether polyol B is 1.7 or more, curability is likely to be exhibited, and the migration component tends to decrease when cured, which is preferable.

In the present invention, the average functional group number f _ave as a polyol mixture of polyether diol A and polyether polyol B is a value calculated from the following formula.

_{f ave = (f A × W} A / M A + f B × W B / M B) / (W A / M A + W B / M B)
Here, f _A is the weight of the average functionality, W _A is polyether diol A polyether diol A, M _A is the number average molecular weight of the polyether diol A, f _B is the average functionality of the polyether polyols B radix, W _B is the weight of the polyether polyol, M _B represents the number average molecular weight of the polyether polyols B.

  The average functional group number f of each of the polyether diol A and the polyether polyol B is a value obtained by the following formula.

f = (1000 fn / Mn) / [{(1000 / Mn) one (USV / fn)} + USV]
Here, fn is the number of hydroxyl groups, Mn is the number average molecular weight, and USV is the degree of unsaturation. The number of hydroxyl groups fn refers to the number of active hydrogen atoms per molecule of initiator used as a raw material when producing polyether diol A or polyether polyol B. For example, ethylene glycol and propylene glycol are 2, and glycerin And trimethylolpropane is 3. In the case of a commercial product, the nominal functional group number was used. The average functional group number f of the polyether diol A is f _A , and the average functional group number f of the polyether diol B is f _B.

  The molar ratio of polyether diol A and polyether polyol B ([polyether diol A] / [polyether polyol B]) used in the urethane prepolymer of the present invention is not particularly limited, but is 99.9 / 0.00. The range of 1-30 / 70 is preferable, and the range of 95 / 5-51 / 49 is more preferable. When the molar ratio of the polyether diol A and the polyether polyol B is in the range of 99.9 / 0.1 to 30/70, there is no generation of undissolved components and the like, and the appearance is good and the handling property is good. Can be expected.

<Polyisocyanate C>
As polyisocyanate C used for the urethane prepolymer of the present invention, a compound having at least two isocyanate groups can be used and is not particularly limited. For example, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 2,4′-diphenylmethane diisocyanate, 4,4′-diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, tolidine diisocyanate, xylylene diisocyanate, 1, 3-phenylene diisocyanate, 1,4-phenylene diisocyanate, lysine diisocyanate, triphenylmethane triisocyanate, tetramethylxylene diisocyanate, 1,6-hexamethylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, isophorone diisocyanate, 1,4- Cyclohexane diisocyanate, norbornane diisocyanate, lysine ester triisocyanate, 1,6,11-undeca Triisocyanate, 1,8-diisocyanate-4-isocyanate methyloctane, 1,3,6-hexamethylene triisocyanate, bicycloheptane triisocyanate, trimethylhexamethylene diisocyanate, isocyanate-containing prepolymers by reacting them with polyols, and these Or a mixture of two or more thereof. Furthermore, modified products of these isocyanates (urethane group, carbodiimide group, allophanate group, urea group, burette group, isocyanurate group, amide group, imide group, uretonimine group, uretdione group or oxazolidone group-containing modified product) and polymethylene Condensates (sometimes referred to as polynuclear bodies) such as polyphenylene polyisocyanate (polymeric MDI) are also included.

  Of these, aliphatic isocyanates, alicyclic isocyanates, and modified products thereof are preferable because flexibility and transparency are easily exhibited. For example, 1,6-hexamethylene diisocyanate, isophorone diisocyanate, aliphatic isocyanate-containing prepolymers are preferable. Polymers, cycloaliphatic isocyanate-containing prepolymers, modified products of these isocyanates (urethane groups, carbodiimide groups, allophanate groups, urea groups, burette groups, isocyanurate groups, amide groups, imide groups, uretonimine groups, uretdione groups, or oxazolidones Group-containing modified products) are preferred. These isocyanates may be used alone or in combination.

  Examples of the isocyanate-containing prepolymer include a reaction product of polyoxyalkylene monoalkyl ether, isotridecanol, hexyldecanol, monool such as ethylhexanol and butyltetraglycol, polyol, monoamine, polyamine and the like and isocyanate.

  The addition amount of polyisocyanate C used in the urethane prepolymer of the present invention is the molar ratio of the total amount of NCO groups possessed by polyisocyanate C and the total amount of OH groups possessed by polyether diol A and polyether polyol B ([total NCO group amount]). / [Total OH group]) is in the range of 0.85 to 1.15 (molar ratio), preferably the total amount of NCO groups possessed by polyisocyanate C, and the OH groups possessed by polyether diol A and polyether polyol B The total molar ratio is in the range of 0.85 to 1.05 (molar ratio). Among these, since a prepolymer having an OH group terminal having high storage stability can be obtained, the ratio of the total amount of OH groups of NCO group and A and B of polyisocyanate C is 0.85 to 0.99 (molar ratio). ) Is particularly preferred. When the molar ratio of the total amount of NCO groups possessed by polyisocyanate C and the total amount of OH groups possessed by polyether diol A and polyether polyol B is less than 0.85 or exceeds 1.15, curing proceeds at an early stage. However, the pot life is too short and it is difficult to mold, and the obtained cured product is also inflexible, so in applications where the stepped portion is large, the flexibility is not sufficient and bubbles are generated without following the step. Have difficulty.

<Other active hydrogen compounds>
In addition to the polyether diol A and the polyether polyol B, other active hydrogen compounds (hereinafter referred to as “other active hydrogen compounds”) can be used in combination without departing from the spirit of the present invention.

  Although it does not specifically limit as another active hydrogen compound, For example, it is a compound which has at least 1 active hydrogen group per molecule, such as water, polyhydric carboxylic acid, a polyamine, a polyol. When other active hydrogen compounds are used, the amount of other active hydrogen compounds added is not particularly limited. However, when the amount is too large, the flexibility and transparency of the cured urethane prepolymer may be reduced. Therefore, it is preferable to use in a range of 40 parts by weight or less with respect to 100 parts by weight of the total amount of polyether diol A and polyether polyol B.

<Method of synthesizing urethane prepolymer>
The method for synthesizing the urethane prepolymer of the present invention is not particularly limited. For example, the above-described polyether diol A, polyether polyol B, and optionally other active hydrogen compound and polyisocyanate C, a urethanization catalyst, Examples thereof include a urethanization reaction method in the presence of a solvent, an antifoaming material, and other additives. Therefore, the obtained urethane prepolymer may contain a urethanization catalyst, an antifoaming material, an additive and the like.

  Here, the temperature of the urethanization reaction is not particularly limited, but is preferably 120 ° C. or lower, more preferably 50 to 110 ° C. If it is 120 degrees C or less, since the urethane prepolymer of control of reaction rate and a predetermined number average molecular weight and structure is easy to be obtained, it is preferable.

  Therefore, the urethanization reaction is preferably performed at 120 ° C. or lower for 1 to 20 hours. The end point of the reaction can be determined by measuring the residual amount of isocyanate by titration or disappearance of the isocyanate peak by IR measurement.

  The urethanization reaction is not particularly limited, but a solvent may be used to facilitate reaction control. Examples of the solvent include methyl ethyl ketone, ethyl acetate, toluene, xylene, acetone, benzene, dioxane, acetonitrile, tetrahydrofuran, diglyme, dimethyl sulfoxide, N-methylpyrrolidone, dimethylformamide and the like. In view of the solubility of the urethane prepolymer, the boiling point of the solvent, etc., ethyl acetate, toluene, methyl ethyl ketone or a mixed solvent thereof is particularly preferable. These solvents may be added at an arbitrary timing such as the initial stage of the reaction, the middle of the reaction, or after the completion of the reaction.

  The urethane prepolymer concentration (including unreacted raw materials excluding the solvent) when a solvent is used during the urethanization reaction is not particularly limited and is selected depending on the use, but preferably in the range of 10 to 90% by weight. More preferably, it is in the range of 20 to 55% by weight. If the urethane prepolymer concentration in the urethane prepolymer solution is in the range of 10 to 90% by weight, the decrease in the reactivity of urethanization is small, and an improvement in handling properties can be expected, which is preferable.

  A known urethanization catalyst can be used when the urethane prepolymer of the present invention is synthesized. For example, a tertiary amine compound, an organometallic compound, etc. are mentioned.

  The tertiary amine compound is not particularly limited, and examples thereof include triethylamine, triethylenediamine, N, N-dimethylbenzylamine, N-methylmorpholine, diazabicycloundecene (also known as DBU) and the like. Two or more types can be used in combination.

  Although it does not specifically limit as an organometallic type compound, A tin type compound and a non-tin type compound can be mentioned.

  Although it does not specifically limit as a tin-type compound, For example, dibutyltin dichloride, dibutyltin oxide, dibutyltin dibromide, dibutyltin dimaleate, dibutyltin dilaurate (alias: DBTDL), dibutyltin diacetate, dibutyltin sulfide, tributyltin Sulfide, tributyltin oxide, tributyltin acetate, triethyltin ethoxide, tributyltin ethoxide, dioctyltin oxide, tributyltin chloride, tributyltin trichloroacetate, dioctyltin dilaurate (also known as DOTDL), tin 2-ethylhexanoate, etc. .

  Although it does not specifically limit as a non-tin type compound, For example, titanium system, such as dibutyltitanium dichloride, tetrabutyltitanate, butoxytitanium trichloride, lead oleate, lead 2-ethylhexanoate, lead benzoate, lead naphthenate, etc. Lead system, iron system such as iron 2-ethylhexanoate and iron acetylacetonate, cobalt system such as cobalt benzoate and cobalt 2-ethylhexanoate, zinc system such as zinc naphthenate and zinc 2-ethylhexanoate, Examples thereof include zirconium naphthenate.

  Among the urethanization catalysts, dibutyltin dilaurate (alias: DBTDL), dioctyltin dilaurate (alias: DOTDL), tin 2-ethylhexanoate and the like are preferable in terms of reactivity and hygiene.

  Catalysts such as tertiary amine compounds and organometallic compounds can be used alone or in combination.

  The amount of the urethanization catalyst added during the synthesis of the urethane prepolymer of the present invention is not particularly limited, but if it is too small, the productivity may be lowered, and if it is too large, the reaction becomes uneven and the physical properties are unstable. Therefore, with respect to 100 parts by weight of the total amount of polyether diol A and polyether polyol B and other active hydrogen compounds added as necessary, the above-mentioned tertiary amine compound has a content of 0.01 to In the case of 15 parts by weight and the above-described organometallic compound, the range of 0.0001 to 5 parts by weight is preferable. After the synthesis, these catalysts may be removed or may remain.

  The urethane prepolymer of the present invention can be chain extended using a chain extender in order to promote high molecular weight. Although not particularly limited, for example, glycols such as ethylene glycol, 1,4-butanediol, neopentyl glycol, butylethylpentanediol, glycerin, trimethylolpropane, pentaerythritol, ethylenediamine, N-aminoethylethanolamine, piperazine, The chain can be extended using a polyvalent amine such as isophoronediamine or xylylenediamine.

  The urethane prepolymer of the present invention is excellent in transparency and uses a polyether diol A and a polyether polyol B having a low degree of unsaturation because the use amount of the tri- or higher functional polyether polyol B is small. Therefore, it is excellent in curability.

<Properties of urethane prepolymer>
The property of the urethane prepolymer of the present invention is preferably liquid. Coating may be difficult in gel or solid form, and insoluble matter may be generated even when dissolved in a solvent.

  The urethane prepolymer of the present invention preferably has a reactive group in the molecule. The reactive group is not particularly limited, but preferably contains a reactive group that reacts with an isocyanate group such as an active hydrogen group, and a reactive group that reacts with an active hydrogen group such as an isocyanate group, and particularly contains a hydroxyl group at the molecular end. It is preferably a hydroxyl group-terminated urethane prepolymer. When the ratio of the total amount of OH groups of the NCO group of the polyisocyanate C, the polyether diol A, and the polyether polyol B is 1.00 or less, the hydroxyl group has a terminal structure. In addition, in the range exceeding 1.00, many isocyanate groups have a terminal structure. Although it does not specifically limit as a terminal structure of the urethane prepolymer of this invention, For example, 1 type (s) or 2 or more types, such as a hydroxyl group, an amino group, an isocyanate group, and an allyl group, are mentioned.

  The number average molecular weight in terms of standard polystyrene of the urethane prepolymer of the present invention is preferably in the range of 30,000 to 300,000, more preferably in the range of 50,000 to 180,000. If the number average molecular weight of the urethane prepolymer is in the range of 30,000 to 300,000, the viscosity of the urethane prepolymer does not become too high, and the resulting urethane cured product can be expected to have good flexibility, which is preferable. The number average molecular weight in terms of standard polystyrene is measured by GPC (gel permeation chromatography) under the conditions of a column temperature of 40 ° C., a flow rate of 1.0 ml / min, and a solvent THF, and a cubic approximate curve calibration curve using standard polystyrene. Can be calculated as

  The viscosity of the urethane prepolymer of the present invention is not particularly limited and is selected depending on the use, but is preferably in the range of 15 to 1000000 Pa · s (25 ° C.), more preferably 15 to 500000 Pa · s (25 ° C.). Range. When the viscosity of the urethane prepolymer is in the range of 15 to 1,000,000 Pa · s (25 ° C.), a resin having a sufficient molecular weight is formed, and good dispersibility in a solvent and coating properties can be expected.

  The urethane prepolymer of the present invention can be used as it is as a urethane pressure-sensitive adhesive, and is suitably used as a component of a two-component curable urethane pressure-sensitive adhesive described later.

<Urethane prepolymer solution>
The urethane prepolymer solution of the present invention is obtained using the urethane prepolymer of the present invention and a solvent, and is a solution having a urethane prepolymer concentration in the range of 10 to 90% by weight, and further in the range of 20 to 55% by weight. preferable. If the concentration of the urethane prepolymer in the urethane prepolymer solution is in the range of 10 to 90% by weight, a decrease in reactivity is small and an improvement in handling properties can be expected, which is preferable.

  The solvent used in the urethane prepolymer solution of the present invention is not particularly limited. For example, methyl ethyl ketone, ethyl acetate, toluene, xylene, acetone, benzene, dioxane, acetonitrile, tetrahydrofuran, diglyme, dimethyl sulfoxide, N-methylpyrrolidone, Examples include dimethylformamide. Among these, ethyl acetate, toluene, methyl ethyl ketone, or a mixed solvent thereof is particularly preferable from the viewpoint of the solubility of the urethane prepolymer, the boiling point of the solvent, and the like.

  The viscosity of the urethane prepolymer solution of the present invention is not particularly limited and is selected depending on the application, but is preferably in the range of 0.1 to 100 Pa · s (25 ° C.), more preferably 1 to 50 Pa · s (25 ° C.). Range. If the viscosity of the urethane prepolymer solution is in the range of 0.1 to 100 Pa · s (25 ° C.), it is preferable because the fluidity of the liquid is moderate and good handling properties can be expected.

  The urethane prepolymer solution of the present invention can be used as a urethane pressure-sensitive adhesive by drying, and is suitably used as a component of a two-component curable urethane pressure-sensitive adhesive described later.

<Two-component curable polyurethane>
The two-component curable polyurethane of the present invention is a cured product obtained by using the urethane prepolymer of the present invention and a crosslinking agent D having reactivity with an active hydrogen group or an isocyanate group.

  The two-component curable polyurethane of the present invention can be provided in any shape such as a film shape, a sheet shape, a plate shape, or a block shape.

  As a method for producing the two-component curable polyurethane of the present invention, for example, the urethane prepolymer of the present invention and a crosslinking agent D having reactivity with an active hydrogen group or an isocyanate group are mixed and cured in a predetermined shape. Can be manufactured by defoaming and drying as necessary. For example, it can be formed into a sheet or film by coating, and can be formed into a plate or block by molding in a mold.

  The use of the two-component curable polyurethane of the present invention is not particularly limited, but is excellent in transparency, flexibility, and low-temperature characteristics. For example, adhesives such as pressure-sensitive adhesives and elastic adhesives for construction, surface protective films, paints, It can be used for the production of elastomers, waterproofing coatings, flooring materials, sealing materials for construction and civil engineering, plasticizers, flexible polyurethane foams, semi-rigid polyurethane foams, rigid polyurethane foams and the like. Among these, since a cured product having good adhesive strength, flexibility, and tackiness can be obtained, it can be suitably used as a two-component curable urethane pressure-sensitive adhesive.

<Crosslinking agent D>
The crosslinking agent D used in the two-component curable polyurethane of the present invention is not particularly limited as long as it is a compound having reactivity with an active hydrogen group or a compound having reactivity with an isocyanate group. For example, isocyanate crosslinking agent, aziridine crosslinking agent, epoxy crosslinking agent, melamine resin, urea resin, metal chelate crosslinking agent, polyol crosslinking agent, amine crosslinking agent, moisture and the like can be mentioned. Since these crosslinking agents are generally liquid, they can be used as they are, but if necessary, they may be diluted with an organic solvent.

  The molar ratio of the total amount of NCO groups derived from polyisocyanate C and the total amount of OH groups derived from polyether diol A and polyether polyol B in the urethane prepolymer ([NCO group total amount] / [OH group total amount]) is 1. In the range of 0.000 or less, the crosslinking agent D is preferably a compound having reactivity with an active hydrogen group. Examples of such a crosslinking agent include isocyanate-based crosslinking agents, aziridine-based crosslinking agents, epoxy crosslinking agents, melamine resins, urea resins, metal chelate-based crosslinking agents, and the like. Among these, an isocyanate-based crosslinking agent and an epoxy crosslinking agent are preferable because they easily exhibit performance such as heat resistance.

  On the other hand, in the urethane prepolymer, in the range where the molar ratio of the total amount of NCO groups derived from polyisocyanate C and the total amount of OH groups derived from polyether diol A and polyether polyol B exceeds 1.00, as crosslinking agent D, A compound having reactivity with an isocyanate group is preferable. Examples of such a crosslinking agent include a polyol crosslinking agent, an amine-based crosslinking agent, and moisture.

  When the urethane prepolymer is obtained by using other active hydrogen compounds in addition to the polyether diol A and the polyether polyol B, the total amount of NCO groups derived from the polyisocyanate C, the polyether diol A, The cross-linking agent described above may be selected using a molar ratio of the polyether polyol B and the total amount of OH groups derived from other active hydrogen compounds.

  As the isocyanate-based crosslinking agent, a compound having at least two isocyanate groups can be used and is not particularly limited. For example, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 2,4′-diphenylmethane diisocyanate, 4,4′-diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, tolidine diisocyanate, xylylene diisocyanate, 1, 3-phenylene diisocyanate, 1,4-phenylene diisocyanate, lysine diisocyanate, triphenylmethane triisocyanate, tetramethylxylene diisocyanate, 1,6-hexamethylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, isophorone diisocyanate, 1,4- Cyclohexane diisocyanate, norbornane diisocyanate, lysine ester triisocyanate, 1,6,11-un Can triisocyanate, 1,8-diisocyanate-4-isocyanate methyloctane, 1,3,6-hexamethylene triisocyanate, bicycloheptane triisocyanate, trimethylhexamethylene diisocyanate, isocyanate-containing urethane prepolymers by reaction of them with polyols, and A mixture of two or more of these may be used. Furthermore, modified products of these isocyanates (urethane group, carbodiimide group, allophanate group, urea group, burette group, isocyanurate group, amide group, imide group, uretonimine group, uretdione group or oxazolidone group-containing modified product) and polymethylene Condensates (sometimes referred to as polynuclear bodies) such as polyphenylene polyisocyanate (polymeric MDI) are also included.

  Among these, since the flexibility and transparency of the cured product of the obtained urethane prepolymer are easily expressed, aliphatic isocyanates, alicyclic isocyanates, and modified products thereof are preferable. For example, 1,6-hexamethylene Diisocyanate, isophorone diisocyanate, aliphatic polyisocyanate-containing urethane prepolymer, alicyclic polyisocyanate-containing urethane prepolymer, modified products of these polyisocyanates (urethane group, carbodiimide group, allophanate group, urea group, burette group, isocyanurate) Group, amide group, imide group, uretonimine group, uretdione group or oxazolidone group-containing modified product) is preferable. These isocyanates may be used alone or in combination. More preferably, it is a polyisocyanate having an allophanate group, an alicyclic isocyanate having an allophanate group, or a mixture containing one or more of these allophanate-modified isocyanates, and is not particularly limited, but for example, Tosoh Corporation Coronate 2770, Coronate 2785, Coronate 2792, and a mixture containing one or more of these.

  Although it does not specifically limit as an epoxy-type crosslinking agent, The amine type epoxy crosslinking agent which has an epoxy group and an amino group, a non-amine type epoxy crosslinking agent is mentioned, for example, bisphenol A, an epichlorohydrin type epoxy resin, ethylene glycidyl ether, Polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,6-hexanediol glycidyl ether, trimethylolpropane triglycidyl ether, diglycidyl aniline, diamine glycidyl amine, N, N, N ', N'- Tetraglycidyl-m-xylylenediamine and 1,3-bis (N, N′-diamineglycidylaminomethyl) cyclohexane, 2,2′one [[2,2 bis (oxirane-2 ylmeth) Shimechiru) Single 1,3 one propanediyl] bis (oxymethylene)] bis oxirane and the like of these two or more mixtures thereof. Although not particularly limited, for example, commercially available products such as Tetrad C and Tetrad X manufactured by Mitsubishi Gas Chemical Company, Denacol EX-411 manufactured by Nagase ChemteX, Denacol EX212, Denacol EX214, and E-5C manufactured by Soken Chemical Co., Ltd. may be mentioned.

  The polyol crosslinking agent is not particularly limited as long as it has two or more active hydrogen groups, and is not limited to ethylene glycol, propylene glycol, 1,4-butylene glycol, 1,5-pentamethylene glycol, 1,6- Examples include hexamethylene glycol, trimethylolpropane, short chain length low molecular weight alkylene polyol, polyoxypropylene polyol, polyoxyethylene propylene polyol polyethylene glycol, polyester polyol, and mixtures of two or more thereof. Among these, since a cured product having excellent curability and transparency can be obtained, the polyol crosslinking agent which does not contain an aromatic ring in the polyol and has a number average molecular weight of less than 8000 is preferable.

  The amine-based crosslinking agent is not particularly limited, but ethylenediamine, trimethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, triethylenetetramine, diethylenetriamine, triaminopropane, 2,2,4-trimethylhexamethylenediamine. , 2-hydroxyethylethylenediamine, N- (2-hydroxyethyl) propylenediamine, (2-hydroxyethylpropylene) diamine, (di-2-hydroxyethylethylene) diamine, (di-2-hydroxyethylpropylene) diamine, ( 2-hydroxypropylethylene) diamine, (di-2-hydroxypropylethylene) diamine, aliphatic polyamines such as piperazine, isophoronediamine, dicyclohexylmethane-4,4 -Alicyclic polyamines such as diamine, phenylenediamine, xylylenediamine, 2,4-tolylenediamine, 2,6-tolylenediamine, diethyltoluenediamine, 3,3'-dichloro-4,4'-diaminodiphenylmethane Aromatic diamines such as 4,4′-bis- (seC-butyl) diphenylmethane, polyoxyalkylene polyamines such as JeffAmine D-2000, and mixtures of two or more thereof.

  Although it does not specifically limit as a functional group number of the crosslinking agent D, For example, the range of 2-6 is preferable, More preferably, it is the range of 2-3. It is preferable that the number of functional groups of the crosslinking agent D is in the range of 2 to 6 because crosslinking is likely to proceed uniformly and curing is not likely to be insufficient.

  The addition amount of the crosslinking agent D used in the two-part curable polyurethane of the present invention is preferably in the range of 0.0001 equivalent to 20 equivalents (molar ratio) with respect to the reactive group of the urethane prepolymer, and 0.01 to 2 A range of equivalents is more preferable, and a range of 0.1 to 1.5 equivalents is particularly preferable. When the addition amount of the crosslinking agent D is in the range of 0.0001 equivalent to 20 equivalents (molar ratio) with respect to the reactive group of the urethane prepolymer (including moisture in the system), it has good curability. However, it is preferable because high transparency can be expected.

<Urethane adhesive>
The urethane pressure-sensitive adhesive of the present invention is not particularly limited as long as it uses the urethane prepolymer of the present invention. Specifically, the urethane prepolymer of the present invention, such as the two-component curable polyurethane of the present invention, or the present invention. The urethane adhesive obtained using the urethane prepolymer solution of the invention is exemplified.

  The urethane pressure-sensitive adhesive of the present invention can be provided in any shape such as a pressure-sensitive adhesive film or pressure-sensitive adhesive sheet laminated on one or more kinds of substrates.

  Examples of the base material used for the pressure-sensitive adhesive sheet using the urethane pressure-sensitive adhesive of the present invention include a release film and a core material. Examples of such a release film include PET, PP, TPX, release films of these silicones, fluorines, etc., and commercially available products include Purex A31, A33, A35, A43 manufactured by Teijin DuPont. The mold release PET is mentioned. Examples of the core material include a nonwoven fabric, a PET film, and a PP film.

  As a laminated structure of the pressure-sensitive adhesive sheet using the urethane pressure-sensitive adhesive of the present invention, for example, a three-layer base material-less pressure-sensitive adhesive sheet sandwiched on both sides with release PET, a five-layer structure using a core material for the pressure-sensitive adhesive layer And a double-sided pressure-sensitive adhesive sheet.

  Although it does not specifically limit as thickness of the adhesive layer in the adhesive sheet using the urethane adhesive of this invention, Preferably it is the range of 10 micrometers-1000 micrometers, More preferably, it is the range of 15 micrometers-250 micrometers, Most preferably 20 μm to 130 μm. Particularly in the case of an optical pressure-sensitive adhesive sheet for a film sensor, a range of 20 μm to 150 μm is preferable, and in the case of an optical pressure-sensitive adhesive sheet for a glass sensor for a touch panel and a cover panel, a range of 50 μm to 250 μm is preferable.

  The shape of the pressure-sensitive adhesive sheet using the urethane pressure-sensitive adhesive of the present invention may be a desired shape. Although not particularly limited, it may be in the form of a roll or may be cut and provided in the form of a sheet.

  Although it does not specifically limit as a manufacturing method of the adhesive sheet using the urethane adhesive of this invention, For example, the component containing the urethane prepolymer of this invention and the component containing the crosslinking agent D are mixed in a predetermined ratio. Examples of the two-component curable polyurethane composition include a coating method using a roll coater, a gravure coater, a micro gravure coater, a reverse coater, an air knife coater, a comma coater, a die coater, and the like. When using these coating methods, it is desirable to apply the two-component curable polyurethane composition to one or both sides of the substrate, and then degas, heat, and dry as necessary. As a heating method, a generally used method such as hot air drying, hot roll drying, infrared irradiation, or the like can be used. The drying temperature is not particularly limited, but is preferably in the range of 50 to 200 ° C, more preferably 70 to 180 ° C, and still more preferably 80 to 150 ° C. When a thermoplastic resin is used as the substrate, the drying temperature is preferably below its melting point. A drying temperature in the range of 50 to 200 ° C. is preferable because deterioration of the base material and change in color tone hardly occur.

  The use of the urethane pressure-sensitive adhesive and pressure-sensitive adhesive sheet of the present invention is not particularly limited, and examples thereof include tapes, labels, seals, cosmetic sheets, non-slip sheets, double-sided pressure-sensitive adhesive tapes, and the like, specifically, packaging tapes. Packaging tapes for office and home use, tapes for labels, masking tapes, craft tapes, medical tapes such as bandages, tapes for wallpaper, foam tapes, elastic tapes for buildings, personal computers, TVs, Tapes for electronic materials used for mobile phones, automobiles, solar cells, other household appliances, optical adhesive sheets used for liquid crystal displays, touch panel adhesion, surface protection tapes and waterproof tapes in manufacturing processes, conductive tapes, heat dissipation tapes, etc. Is exemplified.

  The urethane pressure-sensitive adhesive and pressure-sensitive adhesive sheet of the present invention can be suitably used for optical applications such as touch panel applications because a cured product excellent in transparency can be obtained. Specifically, smartphones, tablet PCs, notebooks It can be suitably used as an optical pressure-sensitive adhesive sheet used in electronic devices such as personal computers. Among these, it can use suitably for adhesion | attachment of the various films inside the said electronic device.

<Optical pressure-sensitive adhesive sheet>
The optical pressure-sensitive adhesive sheet of the present invention is a pressure-sensitive adhesive sheet used for optical applications, obtained using the urethane pressure-sensitive adhesive of the present invention.

  Specific optical uses are not particularly limited, but for example, touch panels and displays such as mobile phones, smartphones, car navigation systems, personal computers, ticket vending machines, peripheral functions such as ITO films, silver meshes, copper meshes, and polarizing plates. An adhesive sheet used for the adhesion of the adhesive film and the like. The operation method of the touch panel is not particularly limited, and can be suitably used for a resistance film type, a capacitance type, an optical type, an ultrasonic type, an electromagnetic induction type, and the like.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not construed as being limited to the following examples unless it exceeds the gist. The materials and evaluation methods used in the following examples and comparative examples are as shown below.

  As raw materials described in Table 1, Table 2, and Table 3, the following were used.

<Raw materials>
1) Polyether diol A, polyether polyol B, and other active hydrogen compounds

<Polyetherdiol A>
Polyols A1 and A3: polyether diols obtained by adding propylene oxide to polyoxypropylene glycol having a bifunctional molecular weight of 400 using an imino group-containing phosphazenium salt (IPZ) catalyst.
Polyols A2 and A4: After adding propylene oxide to polyoxypropylene glycol having a bifunctional molecular weight of 400 using a double metal cyanide complex (DMC) catalyst made in China, an imino group-containing phosphazenium salt (IPZ) catalyst Polyether diol with propylene oxide added.
Polyols A5 and A6: Commercially available general-purpose polyoxypropylene glycol.

<Polyether polyol B>
Polyols B1 and B2: Polyether polyols synthesized by the same method as polyol A1, except that polyoxypropylene polyol having a trifunctional molecular weight of 600 was used as the initiator.
Polyol B3: A commercially available low-unsaturation polyoxypropylene triol.
Polyol B4: Polyether polyol synthesized by the same method as polyol A2, except that pentaerythritol was used as the initiator.
Polyol B5: A polyether polyol synthesized by the same method as polyol B1, except that KOH was used as the catalyst.
Polyol B6: Commercially available general-purpose polyoxypropylene triol.

<Other active hydrogen compounds>
Polyol C1: Diethylene adipate polyester polyol (Tosoh Corporation, Nippon Run 1004)
These polyols A1 to C1 were used after being heated and vacuum dehydrated before use.

2) Polyisocyanate C
Polyisocyanate C1: 1,6-hexamethylene diisocyanate (HDI).
Polyisocyanate C2: isophorone diisocyanate (IPDI).

3) Crosslinking agent D
Crosslinking agent D1: Allophanate modified bifunctional HDI crosslinking agent (Coronate 2770 manufactured by Tosoh Corporation).

(Analysis of polyol properties)
<Hydroxyl value, number average molecular weight>
The hydroxyl value was measured according to the method of JIS-K1557-1. The number average molecular weight of the polyol was defined as the number average molecular weight of the polyol, which was calculated from the product of the number of functional groups of the initiator used for production (the nominal number of functional groups on the market) and the molecular weight per hydroxyl group of the polyol.

<Unsaturation>
It measured according to the method of JIS-K1557-6.

<Molecular weight distribution (Mw / Mn)>
To the sample bottle, 10 mg of polyol and 10 ml of THF were added, dissolved by allowing to stand overnight, and then filtered through a PTFE cartridge filter (0.5 μm) to obtain a sample. RI detector RI8020 was used as a detector, and TSKgelGMR-HHRL × 2 series and HLC-8020GPC were used as measurement columns (both manufactured by Tosoh Corporation). As measurement conditions, measurement was performed under the conditions of a column temperature of 40 ° C., a flow rate of 1.0 ml / min, and a solvent THF, and a molecular weight distribution (Mw / Mn) of a third-order approximation curve using standard polystyrene manufactured by Tosoh Corporation was used as a calibration curve. Analysis was performed.

(Urethane prepolymer synthesis example 1)
Predetermined amounts of polyol A1, polyol B2, and polyisocyanate C1 were added to a four-necked separable flask equipped with a stirrer, a reflux condenser, a nitrogen inlet tube, and a thermometer, and the reaction was performed by raising the temperature to 70 ° C. The NCO group in the reactor contents was traced by dibutylamine back titration, and the completion of the reaction was confirmed using an infrared spectrophotometer to obtain the urethane prepolymer of Example 1.

  Urethane prepolymers other than the urethane prepolymer synthesis example 1 were synthesized in the same manner, and DBTDL was appropriately added using a microsyringe within a range not exceeding 0.02% by weight as a catalyst depending on the reaction rate and the like. In addition, methyl ethyl ketone as a solvent was appropriately added within a range not exceeding 80% by weight depending on the stirring conditions and the like.

(Urethane prepolymer solution production example 1)
To the urethane prepolymer obtained in Synthesis Example 1, ultra-dehydrated methyl ethyl ketone was added as a solvent and dissolved while stirring to prepare a solution having a urethane prepolymer concentration of 20%. The water content of this urethane prepolymer solution was measured with a Karl Fischer moisture meter.

  A urethane prepolymer other than the urethane prepolymer solution Production Example 1 and a urethane prepolymer solution were also added in the same manner as necessary, and the urethane prepolymer concentration was 10% to 100% by weight (none Solvent).

(Two-part cured product production example 1)
About 10 g of the solution obtained in the urethane prepolymer solution production example 1, 0.5 equivalent of the allophanate-modified bifunctional HDI-based cross-linking agent coronate 2770 with respect to the active hydrogen group amount of the urethane prepolymer and the water in the solution. Tosoh Corporation) was added to the sample bottle and stirred with a pencil mixer until uniform. The urethane prepolymer composition was allowed to stand while heating at 50 ° C. for 30 minutes to remove bubbles in the system, and cooled to room temperature. The mixture was coated on release PET (Purex, manufactured by Teijin DuPont Co., Ltd.) with an applicator so as to have a dry thickness of 40 μm, and left to stand in an explosion-proof dryer heated to 80 ° C. for 30 minutes to remove the solvent. At this point, the remaining amount of NCO groups was about 20% immediately after mixing. After completion of drying, release PET (Purex manufactured by Teijin DuPont Co., Ltd.) having a difference in release force from the base material side was pasted back and forth with a roller 3 times so that no bubbles would enter the cured product surface. Then, it left still in a constant temperature room of 23-25 degreeC and 50% RH, and the loss | disappearance of NCO group was confirmed in IR three days later. A sheet having a three-layer structure of release PET / cured product / release PET having a cured product thickness of 40 μm was prepared and used as a cured product evaluation sample (adhesive sheet) of Example 1.

  In the same manner as in Example 1, 0.5 equivalent of allophanate-modified bifunctional HDI-based cross-linking agent Coronate 2770 (manufactured by Tosoh Corp.) is used with respect to the amount of active hydrogen groups in which the urethane prepolymer and water in the solution are combined. Hardened | cured material sheet | seat was produced on conditions and it was set as the cured | curing material evaluation sample of Examples 2-10, respectively.

(Prepolymer property evaluation example)
<GPC number average molecular weight (Mn)>
To the sample bottle, 10 mg of urethane prepolymer and 10 ml of THF were added, and the mixture was dissolved by allowing it to stand for one night, followed by filtering with a PTFE cartridge filter (0.5 μm) to obtain a sample. RI detector RI8020 was used as a detector, and TSKgelGMR-HHRL × 2 series and HLC-8020GPC were used as measurement columns (both manufactured by Tosoh Corporation). The measurement conditions were a column temperature of 40 ° C., a flow rate of 1.0 ml / min, and a solvent THF, and the number average molecular weight was analyzed as a cubic approximate curve calibration curve using standard polystyrene manufactured by Tosoh Corporation.

<Appearance of urethane prepolymer>
The appearance of the urethane prepolymer was visually evaluated, and the evaluation was continued with x indicating a poor appearance with gelation or unevenness and ○ indicating a good appearance.

<Handling properties>
Even if the solution concentration is adjusted to 20%, those that are difficult to coat, those that have high viscosity and cannot be defoamed and difficult to dissolve in a solvent, can be applied, but transfer to the base material over time and handling properties are improved The bad one was evaluated as Δ, and the one that could be applied in the form of a stock solution or solution was evaluated as ○.

<Transparency>
The urethane prepolymer was coated on the release PET so as to have a thickness of 40 μm, and the total light transmittance was measured with a haze meter NDH5000 manufactured by Nippon Denshoku Industries Co. A sample having a total light transmittance of less than 99% excluding was evaluated as x, and a sample having a total light transmittance of 99% or more was evaluated as ◯. Specifically, in the case where the total light transmittance is 91% by overlapping two substrates, and 90% in a three-layer structure, 90/91 = 98.9% and evaluated as x.

<Curing property>
Stir and mix urethane prepolymer and HDI crosslinking agent Coronate 2770 (manufactured by Tosoh Corporation) at a molar ratio of 0.5 equivalent to the reactive group of the urethane prepolymer (including moisture in the system), and then dry and cure. Then, the curability was evaluated by touching with a finger. Insufficient curing x liquid, x insufficient curing, migration component may adhere to fingers and stain surrounding area, Δ, migration component has few tacks, o Those that progressed too early and the pot life was short and difficult to form were marked as XX.

(Example of evaluation of cured product characteristics)
<Flexibility>
According to the two-part cured product production example, the obtained cured product was peeled off from the release PET and folded to obtain a measurement sample. Using a dynamic viscoelasticity measuring device (UBE, Rheogel E-4000), measurement is performed at a measurement temperature of −80 ° C. to 200 ° C., a temperature increase rate of 2 ° C./min, a frequency of 1 Hz, and a shear mode condition. The storage elastic modulus G ′ at ° C. was evaluated. When G ′ at 25 ° C. is 2 × 10 ⁵ Pa or less, flexibility ○, and when G ′ exceeds 2 × 10 ⁵ Pa, flexibility is ×.

<Low temperature characteristics>
According to the two-part cured product production example, the obtained cured product was peeled off from the release PET and folded to obtain a measurement sample. Using a dynamic viscoelasticity measuring device (UBE, Rheogel E-4000), measurement is performed at a measurement temperature of −80 ° C. to 200 ° C., a temperature increase rate of 2 ° C./min, a frequency of 1 Hz, and a shear mode condition, and then stored. The temperature at which the peak value of tan δ, which is the ratio of the loss elastic modulus G ″ to the elastic modulus G ′, was evaluated as the glass transition temperature. If the glass transition temperature is −40 ° C. or lower, the low-temperature characteristics ○, and the glass transition temperature is −40. When the temperature exceeded ℃, the low temperature characteristic was evaluated as x.

<Transparency>
According to the two-part cured product production example, the release PET of the obtained pressure-sensitive adhesive sheet was peeled off on one side and pasted onto a PMMA substrate (Mitsubishi Rayon Co., Ltd., Acrylite L # 001 clear) using a roller. The release PET on the other side was peeled off, and the total light transmittance and HAZE were measured with NDH5000. The total light transmittance obtained by subtracting the total light transmittance of the PMMA base material alone was 99% or more, and HAZE was 0.8%. A value of less than ◯, and a case where the total light transmittance or the value of HAZE did not reach the standard was rated as x. Specifically, when the total light transmittance of the PMMA substrate was 91% and the two-layer structure of PMMA2 and the adhesive was 90%, 90/91 = 98.9%, and x was evaluated.

<Adhesive properties>
According to the two-part cured product production example, the release PET of the obtained pressure-sensitive adhesive sheet was peeled off on one side, and a 25 μm-thick PET film Toray Co., Ltd. Lumirror S-10 was lined on the pressure-sensitive adhesive surface. The test piece was cut to a width of 25 mm and roll-bonded to Eagle XG made by alkali-free glass plate Corning in accordance with JIS Z0237. Using a Tensilon RTG-1210 manufactured by Orientec Co., Ltd., a 180 ° peel test was performed in accordance with JIS Z0237, and 180 ° peel strength (N / 25 mm) was measured. The measurement was performed in an atmosphere of 23 ° C. and 50% RH under conditions of a peeling angle of 180 ° and a tensile speed of 300 mm / min. The number of tests was 2 times or more, the average value was calculated, 3N / 25mm or more was marked with ◯, and less than 3N / 25mm was marked with x.

  The results of Examples 1 to 9 and Comparative Examples 1 to 3 are shown in Table 2, and the results of Example 10 and Comparative Examples 4 to 10 are shown in Table 3.

Examples 1-10.
Urethane prepolymers were synthesized according to the formulations shown in Tables 2 and 3, and their properties were evaluated.

  In all cases, there was no poor appearance and no deterioration in handling properties, and transparency and curability were good. Moreover, it turned out that the hardened | cured material obtained using the synthetic | combination urethane prepolymer can obtain the hardened | cured material with a softness | flexibility and a favorable low temperature characteristic. Furthermore, in the evaluation as an optical adhesive, it was found that the adhesive strength and transparency were high.

Comparative Example 1
According to the formulation shown in Table 2, the synthesis of urethane prepolymer was examined. Although the reaction was completed, the viscosity rapidly increased at the end of the reaction and a gel component insoluble in the solvent was generated, making it difficult to use as a urethane prepolymer.

Comparative Example 2
The polyol B2 of Example 1 was changed to polyol A1, a urethane prepolymer was synthesized using 100 parts of polyol A1, and properties were evaluated. Although there was no appearance defect and handling property deterioration and transparency was good, the curability was not seen and it was difficult to use as a urethane prepolymer.

Comparative Example 3
The NCO / OH ratio of Example 2 was reduced from 0.95 to 0.8 to synthesize a urethane prepolymer, and the properties were evaluated. The appearance was not poor and the handling property was not deteriorated and the transparency was good, but the pot life at the time of curing was short, and the curing was too advanced, resulting in poor moldability and curability.

  In addition, the cured product obtained using the synthesized urethane prepolymer cannot be expected to follow unevenness because of its lack of flexibility, and its adhesive strength is low due to its low adhesive strength when evaluated as an optical adhesive. It was inferior to.

Comparative Examples 4-6.
From the formulation of Example 2, the urethane prepolymer was synthesized by changing the polyol A, the polyol B, or both to one having a high degree of unsaturation, and the properties were evaluated. Although there was no poor appearance and no deterioration in transparency, it was inferior in handling properties due to the transition to the base material over time after coating, and it was difficult to use as a prepolymer because of insufficient curing .

  Moreover, although the hardened | cured material obtained using the synthetic | combination urethane prepolymer was favorable in a softness | flexibility and a low temperature characteristic, hardening was inadequate and adhesive force was not expressed.

Comparative Example 7
From the formulation of Comparative Example 6, a urethane prepolymer having a reduced NCO / OH ratio from 0.95 to 0.8 to enhance curability was synthesized and evaluated for properties. There was no poor appearance and no deterioration in handling properties, and transparency was good, but the pot life at the time of curing was short, the curing progressed too much and the moldability and curability were inferior. It was difficult to achieve both.

  In addition, the cured product obtained using the synthesized urethane prepolymer cannot be expected to follow unevenness because of its lack of flexibility, and its adhesive strength is low due to its low adhesive strength when evaluated as an optical adhesive. It was inferior to.

Comparative Example 8
From the formulation of Comparative Example 6, the synthesis of a urethane prepolymer having an increased curability by increasing the ratio of polyol B from 30% to 80% was examined. Although the reaction was completed, a gel component insoluble in the solvent was generated, and it was difficult to use as a prepolymer.

Comparative Example 9
The composition of Example 2 was changed to those in which the molecular weights of polyol A and polyol B were lowered, and urethane prepolymers were synthesized, and properties were evaluated. The appearance was not poor and the handling property was not deteriorated, and the transparency was good, but the pot life at the time of curing was short, the curing progressed too much and the moldability and curability were inferior.

  In addition, the cured product obtained using the synthesized urethane prepolymer cannot be expected to follow unevenness because of its lack of flexibility, and its adhesive strength is low due to its low adhesive strength when evaluated as an optical adhesive. It was inferior to.

Comparative Example 10
From the formulation of Example 2, 70 parts by weight of polyol A was changed to 70 parts by weight of polyester polyol C, a urethane prepolymer was synthesized, and the properties were evaluated. The transparency of the urethane prepolymer was poor and the handling property was poor because of its high viscosity.

  The cured product obtained by using the urethane prepolymer has a low glass transition temperature and is inferior in low-temperature characteristics, and has poor transparency. Moreover, since the cured product has no flexibility, it cannot be expected to follow the unevenness, and in the evaluation as an optical pressure-sensitive adhesive, it has poor optical properties because of its low transparency.

Claims (11)

A urethane prepolymer obtained using polyether diol A, polyether polyol B, and polyisocyanate C,
The degree of unsaturation of the polyether diol A is 0.07 meq / g or less, and the number average molecular weight is in the range of 3000 to 30000,
The polyether polyol B is a tri- or higher functional polyether polyol, the degree of unsaturation is 0.07 meq / g or less, and the number average molecular weight is in the range of 5000 to 40000,
The ratio of the NCO group of the polyisocyanate C to the total amount of OH groups of the polyether diol A and the polyether polyol B is in the range of 0.85 to 1.15 (molar ratio), and the polyether diol A urethane prepolymer, wherein the upper limit of the average functional group number f _ave as a polyether polyol mixture of A and polyether polyol B is 2.20. The degree of unsaturation (meq / g) and the number average molecular weight of the polyether diol A are represented by the following formula:
Unsaturation ≦ Number average molecular weight × 0.00001
The urethane prepolymer according to claim 1, wherein: The urethane prepolymer according to claim 1 or 2, wherein the polyisocyanate C is at least one selected from the group consisting of aliphatic isocyanates, alicyclic isocyanates, and modified products thereof. The urethane prepolymer according to any one of claims 1 to 3, wherein the number average molecular weight (Mn) in terms of standard polystyrene is in the range of 30,000 to 300,000. The urethane prep according to any one of claims 1 to 4, wherein the polyether diol A is obtained by ring-opening polymerization of alkylene oxide using an imino group-containing phosphazenium salt catalyst. polymer. A urethane prepolymer solution obtained by using the urethane prepolymer according to any one of claims 1 to 5 and a solvent, wherein the concentration of the urethane prepolymer is in the range of 10 to 90% by weight. Two-component curing characterized by being a cured product obtained by using the urethane prepolymer according to any one of claims 1 to 5 and a crosslinking agent D having reactivity with an active hydrogen group or an isocyanate group. Type polyurethane. The two-component curable polyurethane according to claim 7, wherein the crosslinking agent D is used in a range of 0.0001 equivalent to 20 equivalents (molar ratio) with respect to the reactive group of the urethane prepolymer. The urethane adhesive containing the urethane prepolymer in any one of Claims 1-5. A two-component curable urethane pressure-sensitive adhesive obtained by using the two-component curable polyurethane according to claim 7 or 8. An optical pressure-sensitive adhesive sheet obtained by using the urethane pressure-sensitive adhesive according to claim 9 or 10.