JP2016204468A - Urethane prepolymer, and two-liquid type urethane adhesive using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a urethane prepolymer with a low viscosity 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 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 of 3,000 to 30,000; and the ratio of NCO groups which the polyisocyanate C has to the total amount of OH groups which the polyether diol A has is in the range of 0.85 to 1.15 (molar ratio). 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 curable urethane pressure-sensitive 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 the polyether polyol, and uses a large amount of trifunctional polyether polyol. Therefore, the viscosity of the urethane prepolymer is increased, resulting in poor handling properties and curing. In this case, the curing was too advanced, and it was insufficient for applications requiring impact resistance. In addition, in applications where the level difference portion is large, there are problems that the flexibility is not sufficient and bubbles cannot be generated following the level difference, and that thixotropy is manifested and handling at the time of coating is poor. Furthermore, since adhesive force was low, it was inferior to the adhesiveness to a base material. Moreover, since the molecular weight of the polyol to be used is low and the amount of isocyanate used is relatively large, there is a concern that the solubility in a solvent is poor and an appearance defect due to an undissolved part occurs.

JP 2006-18295 A

  The present invention has been made in view of the above-described background art, and its purpose is a urethane prepolymer having a low viscosity, being able to be handled well and having 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 can solve the above problems by blending a specific degree of unsaturation, a polyether diol having a molecular weight, and a polyisocyanate at a specific blending ratio. As a result, 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 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 3000 to 30000, and the NCO group of the polyisocyanate C, and the total amount of OH groups of the polyether diol A The urethane prepolymer characterized in that the ratio of is in the range of 0.85 to 1.15 (molar ratio).

[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 according to [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. .

  [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 in a concentration 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 polyurethane as described in [8] above, wherein the crosslinking agent D is contained in a range of 2 to 20 equivalents (molar ratio) with respect to the reactive group of the urethane prepolymer.

  [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].

  Hereinafter, the present invention will be described in detail.

  The urethane prepolymer of the present invention has a low viscosity and 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 exhibits impact resistance and adhesiveness, it can be suitably used as a two-component curable urethane adhesive.

  Hereinafter, the present invention will be described in detail.

A urethane prepolymer obtained by using the polyether diol A of the present invention 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 3000 to 30000, and the NCO group of the polyisocyanate C, and the total amount of OH groups of the polyether diol A The ratio is in the range of 0.85 to 1.15 (molar ratio).

<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. Incidentally, the R ₁ and R ₂ may be bonded to form a ring structure, R ₁ s or R ₂ together may form a ring structure together. 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.

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

  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 catalyst is removed or left in a state where the cesium metal compound catalyst, double metal cyanide complex catalyst, phosphazene catalyst, imino group is contained. 1 for phosphazenium salt catalyst, barium hydroxide catalyst, etc. Or a method in which addition of an alkylene oxide is exemplified by 2 or more used in two or more stages until a predetermined molecular weight.

<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, impact resistance, and transparency are easily exhibited. For example, 1,6-hexamethylene diisocyanate, isophorone diisocyanate, fat Group isocyanate-containing prepolymer, alicyclic isocyanate-containing prepolymer, modified products of these isocyanates (urethane group, carbodiimide group, allophanate group, urea group, burette group, isocyanurate group, amide group, imide group, uretonimine group, Uretodione group or oxazolidone group-containing modified product) is 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 ([total amount of NCO groups] / [total amount of OH groups]. ] Is in a range of 0.85 to 1.15 (molar ratio), preferably 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 is 0.85 to 1. .05 (molar ratio). Among these, since an OH group-terminated prepolymer having high storage stability is obtained, the ratio of the total amount of OH groups of the polyisocyanate C and NCO groups of the polyisocyanate C to the polyether diol A is 0.85 to 0.99 (mol) The range of ratio) is particularly preferred. When the molar ratio of the total amount of NCO groups possessed by the polyisocyanate C and the total amount of OH groups possessed by the polyether diol A is less than 0.85 or exceeds 1.15, curing proceeds too early and the pot life However, since the obtained cured product is also not flexible, in applications where the step portion is large, the flexibility is not sufficient, and bubbles are generated without being able to follow the step, making it difficult to use.

<Active hydrogen compound B>
In addition to the polyether diol A, other active hydrogen compounds B (hereinafter referred to as “active hydrogen compounds B”) can be used in combination without departing from the spirit of the present invention. Although it does not specifically limit as the active hydrogen compound B, 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 the active hydrogen compound B is used, the amount of addition is not particularly limited, but if it is too much, the impact resistance and flexibility of the cured urethane prepolymer may be reduced. It is preferably used in a range of 100 parts by weight or less, more preferably 30 parts by weight or less, based on 100 parts by weight of ether diol A. Most preferably, the amount of the active hydrogen compound B is 10 parts by weight or less with respect to 100 parts by weight of the polyether diol A. In this case, the trifunctional or higher functional polyether polyol in the active hydrogen compound B is less than 0.1 parts by weight. It is preferable that Moreover, it is preferable not to contain a trifunctional or higher functional polyether polyol having an unsaturation degree of 0.07 meq / g or less and a number average molecular weight in the range of 5000 to 40000.

  When the active hydrogen compound B is used in addition to the polyether diol A, the addition amount of the polyisocyanate C includes the total amount of NCO groups of the polyisocyanate C and the total amount of OH groups of the polyether diol A and the active hydrogen compound B. The molar ratio is preferably 0.85 to 1.15 (molar ratio).

<Method of synthesizing urethane prepolymer>
The method for synthesizing the urethane prepolymer of the present invention is not particularly limited. For example, the polyether diol A, and optionally the active hydrogen compound B and the polyisocyanate C, a urethanization catalyst, a solvent, an antifoaming material, In addition, the method of making a urethanation reaction in presence of an additive etc. is mentioned. 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 30 to 70% 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 (also known as DBTDL), dioctyltin dilaurate (also known as 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, 0.01 to 15 parts by weight of the above-mentioned tertiary amine compound is described above with respect to 100 parts by weight of the total amount of polyether diol A and active hydrogen compound B added as necessary. In the case of an 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.

  Since the urethane prepolymer of the present invention uses a large amount of polyether diol, a two-component polyurethane cured product having a low viscosity and excellent handling properties and good impact resistance, flexibility and low-temperature characteristics when crosslinked is obtained. Moreover, since polyether diol A with low unsaturation is used, 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 and the polyether diol A is 1.00 or less, the hydroxyl group is 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 terminal structure of the urethane prepolymer of this invention, For example, 1 type, or 2 or more types, such as a hydroxyl group, an amino group, an isocyanate group, and an allyl group, is 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 30000-300000, and more preferably in the range of 35000-80000. 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 100 to 30000 Pa · s (25 ° C.). And most preferably in the range of 100 to 5000 Pa · s. 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. The urethane prepolymer solution is a solution having a urethane prepolymer concentration in the range of 10 to 90% by weight, and further in the range of 30 to 70% 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 use, but is preferably in the range of 0.1 to 100 Pa · s (25 ° C.), more preferably in the range of Pa · s (25 ° C.). It is. 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 high flexibility and low temperature characteristics and excellent impact resistance and adhesiveness 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-part 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.

  In the urethane prepolymer, 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 ([total amount of NCO groups] / [total amount of OH groups]) is 1.00 or less. As the crosslinking agent D, a compound having reactivity with an active hydrogen group is preferable. 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 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 in the urethane prepolymer exceeds 1.00, the crosslinking agent D is It is preferable that the compound has reactivity. 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 an active hydrogen compound B in addition to the polyether diol A, it is derived from the total amount of NCO groups derived from the polyisocyanate C, and from the polyether diol A and the active hydrogen compound B. The cross-linking agent described above may be selected using a molar ratio with the total amount of OH groups.

  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, impact resistance, and transparency of the cured product of the obtained urethane prepolymer are easily expressed, aliphatic isocyanates, alicyclic isocyanates, and modified products thereof are preferable. 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). 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 [[2,2bis (oxirane-2-ylylmethoxy) Chill) 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, trimethylol propane, short chain 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-component curable polyurethane of the present invention is preferably in the range of 2 to 20 equivalents (molar ratio), more preferably in the range of 2 to 15 equivalents, relative to the reactive group of the urethane prepolymer. A range of 3 to 10 equivalents is particularly preferable. If the addition amount of the crosslinking agent D is in the range of 2 to 20 equivalents (molar ratio) with respect to the reactive group of the urethane prepolymer (including moisture in the system), it has good curability and high It is preferable because flexibility 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 a 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 are particularly suitable for applications requiring impact resistance, for example, adhesion of fragile base materials such as glass, prevention of scattering, adhesion of electronic devices, etc. that are vulnerable to vibration and impact, etc. Specifically, it can be used for optical applications such as touch panel applications and electrical / electronic component applications. Although it does not specifically limit as a specific use, The adhesive sheet for optics used for electronic devices, such as a smart phone, a tablet PC, a notebook personal computer, and the protection tape of an electronic component are illustrated. 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 the raw materials described in Table 2 and Table 3, the following were used.

<Raw materials>
1) Polyetherdiol A, active hydrogen compound B

<Polyetherdiol A>
Polyols A1, A3 and A7: 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 And polyether diol polyols A5 and A6 to which propylene oxide is added: commercially available general-purpose polyoxypropylene glycol.
<Active hydrogen compound B>
Polyol B1: Commercially available general-purpose polyoxypropylene triol.
Polyol B2: Diethylene adipate-based polyester polyol (Nipporan 1004 manufactured by Tosoh Corporation).
These polyols A1 and B2 were used after being heated and vacuum dehydrated before use.

2) Polyisocyanate C
Isocyanate C1: 1,6-hexamethylene diisocyanate (HDI).

3) Crosslinking agent D
Cross-linking agent D1: 50% by weight of a mixture of 50% by weight of an allophanate-modified bifunctional HDI-based crosslinker (Coronate 2770 manufactured by Tosoh Corporation) and an approximately trifunctional nurate-modified HDI-based cross-linking agent (Coronate HX 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-H _HR L × 2 in 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 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)
Super-dehydrated methyl ethyl ketone was added as a solvent to the urethane prepolymer obtained in Synthesis Example 1 and dissolved by stirring while heating to prepare a solution having a urethane prepolymer concentration of 50%. The water content of this urethane prepolymer solution was measured with a Karl Fischer moisture meter.

  The urethane prepolymer other than the urethane prepolymer solution production example 1 and the urethane prepolymer solution are added with a solvent in the same manner as necessary, and the urethane prepolymer concentration is 30% to 100% by weight (none Solvent).

(Two-part cured product production example 1)
About 10 g of the solution obtained in Urethane Prepolymer Solution Production Example 1, 7 equivalent of crosslinking agent D1 (the amount of Coronate 2770 and Coronate HX manufactured by Tosoh Corporation) with respect to the amount of active hydrogen groups combined with the urethane prepolymer and water in the solution. The equivalent mixture) 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) with an applicator so as to have a dry thickness of 40 μm, and left 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, the same conditions were used using 7 equivalents of a cross-linking agent D1 (equivalent mixture of Coronate 2770 and Coronate HX manufactured by Tosoh Corporation) based on the amount of active hydrogen groups combined with the urethane prepolymer and water in the solution. A cured product sheet was prepared and used as a cured product evaluation sample of Examples 2 to 10, respectively.

(Urethane prepolymer properties 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.

<Viscosity>
Using MCR-300 manufactured by Anton-Paar, the viscosity of the urethane prepolymer alone was measured under the condition of 25 ° C. The angular velocity dependency was evaluated in the range of 0.001 to 100 (1 / second), and the average value in a constant range was defined as the viscosity.

<Handling properties>
When the solution concentration is adjusted to 70%, those that are difficult to coat and those that are poorly dispersible in the solvent of the urethane prepolymer are acceptable. △, the thing which can be applied in stock solution or solution state was evaluated as ◯.

<Curing property>
The urethane prepolymer and the isocyanate crosslinking agent D1 (equivalent mixture of Coronate 2770 and Coronate HX manufactured by Tosoh Corporation) are stirred and mixed at a molar ratio of 7 equivalents with respect to the reactive group of the urethane prepolymer (including moisture in the system). When dried and cured, 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, have a short pot life, and were difficult to mold were also marked as xx.

(Example of evaluation of cured product characteristics)
<Impact resistance>
In accordance with the two-part cured product production example, the obtained cured product is peeled off from the release PET, and the adhesive layer is 200 μm in 5 layers, and bonded to a 5 cm square 0.7 mm thick glass substrate, and the other side is also thick. A measurement sample was obtained by pasting on a glass substrate having a thickness of 0.7 mm.

  A steel ball having a diameter of 5/8 inch was dropped from the height of 50 cm to the center of the measurement sample, and a test piece that was not cracked, floated or peeled even after repeated three times was marked as ◯.

<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 UBM 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 ′ was evaluated. Flexibility ◯ when G ′ at 25 ° C. is 3.5 × 10 ⁵ Pa or less, and flexibility when X ′ exceeds 3.5 × 10 ⁵ Pa.

<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 UBM 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 temperature at which the peak value of tan δ, which is the ratio of the loss elastic modulus G to “,” was evaluated as the glass transition temperature. If the glass transition temperature is −40 ° C. or lower, the low-temperature characteristics ○, the glass transition temperature exceeds −40 ° C. In this case, the low-temperature characteristics were evaluated as x.

<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 are shown in Table 2, and the results of Comparative Examples 1 to 6 are shown in Table 3.

Examples 1-9.
According to the formulation shown in Table 2, a urethane prepolymer and a two-part cured product were synthesized and evaluated for properties.

  In all cases, the viscosity was low, the handling property was good, and the curability was good. Moreover, it turned out that the hardened | cured material obtained using the synthetic | combination urethane prepolymer has favorable impact resistance, and the hardened | cured material compatible with a softness | flexibility and a low temperature characteristic is obtained. Furthermore, in the evaluation as a pressure-sensitive adhesive, it was found that the adhesive strength was high and adhesion to a substrate could be expected.

Comparative Example 1
According to the formulation shown in Table 3, a urethane prepolymer was synthesized using a polyether diol having a high degree of unsaturation, and the properties were evaluated. Although there was a transition component than the cured product, the viscosity was low and the handling property was acceptable, but the curability was not seen and the use as a urethane prepolymer was difficult.

Comparative Example 2
A urethane prepolymer was synthesized by changing the polyol A5 of Comparative Example 1 to a polyol A6 having a low molecular weight, and the properties were evaluated. Although the viscosity is low, the dispersibility in a solvent is poor and the handling property is poor, the pot life at the time of curing is short, the curing is too advanced, and the moldability and curability are poor.

  In addition, the cured product obtained using the synthesized urethane prepolymer is poor in flexibility and inferior in impact resistance. In the use as an adhesive, the adhesive property is poor, and therefore, in an application with unevenness, the cured product is uneven. It was not expected to follow.

Comparative Example 3
Polyurethane A6 of Comparative Example 2 was changed to polyol A7 having a low degree of unsaturation but a low molecular weight, and a urethane prepolymer was synthesized and evaluated for properties. Although the viscosity is low, the dispersibility in a solvent is poor and the handling property is poor, the pot life at the time of curing is short, the curing is too advanced, and the moldability and curability are poor.

  In addition, the cured product obtained using the synthesized urethane prepolymer is poor in flexibility and inferior in impact resistance. In the use as an adhesive, the adhesive property is poor, and therefore, in an application with unevenness, the cured product is uneven. It was not expected to follow.

Comparative Example 4
A urethane prepolymer was synthesized by reducing the ratio of the polyether diol A3 and the isocyanate C1 in Example 3 from NCO / OH = 0.95 to 0.8, and the properties were evaluated. Although the viscosity and handling properties were good, the pot life at the time of curing was short, the curing was too advanced, and the moldability and curability were poor.

Comparative Example 5
The synthesis of the urethane prepolymer was examined using only the trifunctional polyether polyol without using the polyether diol A. 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 6
A urethane prepolymer was synthesized using only polyester polyol without using polyether diol A, and the properties were evaluated. The viscosity was high and the handling property was inferior, 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 had good adhesion, but it was poor in flexibility and inferior in impact resistance, and had high glass transition temperature and low adhesion reliability at low temperatures. Could not be expected.

Claims (11)

A urethane prepolymer obtained by using polyether diol A 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 3000 to 30000, and the NCO group of the polyisocyanate C, and the total amount of OH groups of the polyether diol A The urethane prepolymer characterized in that the ratio of is in the range of 0.85 to 1.15 (molar ratio). 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 an alkylene oxide using an imino group-containing phosphazenium salt catalyst. polymer. The urethane prepolymer solution whose density | concentration of the said urethane prepolymer obtained using the urethane prepolymer and solvent in any one of Claims 1 thru | or 5 is the range of 10 to 90 weight%. A two-component curable polyurethane 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. The two-component curable polyurethane according to claim 7, wherein the crosslinking agent D is used in a range of 2 to 20 equivalents (molar ratio) with respect to the reactive group of the urethane prepolymer. A urethane pressure-sensitive adhesive comprising the urethane prepolymer according to claim 1. A two-component curable urethane pressure-sensitive adhesive obtained by using the two-component curable polyurethane according to claim 7 or 8. The optical adhesive sheet obtained using the urethane adhesive of Claim 9 or 10.